AU2002323712B2

AU2002323712B2 - A field actuated ink jet

Info

Publication number: AU2002323712B2
Application number: AU2002323712A
Authority: AU
Inventors: Kia Silverbrook
Original assignee: Silverbrook Research Pty Ltd
Current assignee: Zamtec Ltd
Priority date: 1997-07-15
Filing date: 2002-12-24
Publication date: 2006-02-16
Anticipated expiration: 2018-07-15
Also published as: AU2002323712A2

Description

WO 99/03680 PCT/AU98/00548 1 A FIELD ACTUATED INK JET Field of Invention The present invention relates to the field of ink jet printing systems.

Background of the Art Many different types of printing have been invented, a large number of which are presently in use. The known forms of print have a variety of methods for marking the print media with a relevant marking media.

Commonly used forms of printing include offset printing, laser printing and copying devices, dot matrix type impact printers, thermal paper printers, film recorders, thermal wax printers, dye sublimation printers and ink jet printers both of the drop on demand and continuous flow type. Each type of printer has its own advantages and problems when considering cost, speed, quality, reliability, simplicity of construction and operation etc.

in recent years, the field of ink jet printing, wherein each individual pixel of ink is derived from one or more ink nozzles has become increasingly popular primarily due to its inexpensive and versatile nature.

Many different techniques of ink jet printing have been invented. For a survey of the field, reference is made to an article by J Moore, "Non-Impact Printing: Introduction and Historical Perspective", Output Hard Copy Devices, Editors R Dubeck and S Sherr, pages 207 220 (1988).

Ink Jet printers themselves come in many different types. The utilisation of a continuous stream ink in ink jet printing appears to date back to at least 1929 wherein US Patent No. 1941001 by Hansell discloses a simple form of continuous stream electro-static ink jet printing.

US Patent 3596275 by Sweet also discloses a process of a continuous ink jet printing including the step wherein the ink jet stream is modulated by a high frequency electro-static field so as to cause drop separation. This technique is still utilised by several manufacturers including Elmjet and Scitex (see also US Patent No. 3373437 by Sweet el al) Piezo-electric ink jet printers are also one form of commonly utilised ink jet printing device. Piezo-electric systems are disclosed by Kyser et. al. in US Patent No. 3946398 (1970) which utilises a diaphragm mode of operation, by Zolten in US Patent 3683212 (1970) which discloses a squeeze mode of operation of a piezo electric crystal, Stemme in US Patent No. 3747120 (1972) discloses a bend mode of piezo-electric operation, Howkins in US Patent No. 4459601 discloses a Piezo electric push mode actuation of the ink jet stream and Fischbeck in US 4584590 which discloses a sheer mode type of piezo-electric transducer element.

Recently, thermal ink jet printing has become an extremely popular form of ink jet printing. The ink jet 3C printing techniques include those disclosed by Endo et al in GB 2007162 (1979) and Vaught et al in US Patent 4490728. Both the aforementioned references disclosed ink jet printing techniques rely upon the activation of an electrothermal actuator which results in the creation of a bubble in a constricted space, such as a nozzle, which thereby causes the ejection of ink from an aperture connected to the confined space onto a relevant print media.

Printing devices utilising the electro-thermal actuator are manufactured by manufacturers such as Canon and Hewlett Packard.

As can be seen from the foregoing, many different types of printing technologies are available. Ideally, a printing technology should have a number of desirable attributes. These include inexpensive construction and SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/00548 2 operation, high speed operation, safe and continuous long term operation etc. Each technology may have its own advantages and disadvantages in the areas of cost, speed, quality, reliability, power usage, simplicity of construction operation, durability and consumnables.

Many ink jet printing mechanisms are known. Unfortunately, in mass production techniques, the production of ink jet heads is quite difficult. For example, often, the orifice or nozzle plate is constructed separately from the ink supply and ink ejection mechanism and bonded to the mechanism at a later stage (Hewlett-Packard Journal, Vol. 36 no 5, pp33-37 (1985)). These separate material processing steps required in handling such precision devices often adds a substantially expense in manufacturing.

Additionally, side shooting ink jet technologies Patent No. 4,899,181) are often used but again, this limit the amount of mass production throughput given any particular capital investment.

Additionally, more esoteric techniques are also often utilized. These can include electroforming of nickel stage (Hewlett-Packard Journal, Vol. 36 no 5, pp 33 3 7 (1985)), electro-discharge machining, laser ablation (U.S.

Patent No. 5,208,604), micro-punching, etc.

The utilisation of the above techniques is likely to add substantial expense to the mass production of ink jet print heads and therefore add substantially to their final cost.

It would thereibre be desirable if an efficient system for the mass production of ink jet print heads could be developed.

Summary of the invention It is an object of the present invention to provide for an ink jet printing mechanism having a series of irk ejection nozzles, with the nozzles including an internal selective actuator mechanism activated on a nozzle by nozzle basis by the placement of a field around said nozzles.

In accordance with an aspect of the present invention there is provided an ink jet printing nozzle arrangement comprising a nozzle chamber having an ink ejection port at one end; a plunger constructed from soft magnetic material and positioned between the nozzle chamber and an ink chamber, which allows for the supply of ink to the nozzle chamber, and an electric coil located adjacent to the plunger and electrically connected to a nozzle activation signal wherein, upon activation, the plunger is caused to move from an ink loaded position to an ink ejection position and thereby causes the ejection of ink from the ink chamber through the ejection port Further, the ink ejection nozzle can comprise an armnature plate constructed from soft magnetic material and the plunger is attracted to the armature plate on the activation of the coil. A cavity is defined by the plunger in which the electric coil is located, which has its dimensions reduced as a result of movement of the plunger, the plunger further having a series of fluid release slots in fluid communication with the cavity and the ink chamber, allowing for the expulsion of fluid under pressure in the formed cavity. Preferably, the ink jet printing nozzle comprises a resilient means for assisting in the return of the plunger front the ink ejection position to the ink loaded position after the ejection of ink from the ink ejection port. Advantageously, the resilient means comprises a torsional spring of an arcuate construction having a circumferential profile substantially the same as that of the plunger.

In accordance with a fluther aspect of the present invention, there is provided an ink jet printing nozzle arrangement constructed in accordance with the previous aspect of the invention wherein the plunger has along one surface a series of slots. This surface forms the inner radial surface defining the cavity between the plunger and the electric coil. Further, the plunger has no fluid release slots in its top surface that defines the top wall of the cavity SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/00548 3 formed. Upon reduction of the cavity dimensions due to the downward movement of the plunger, induced by the electric coil, an ink flow through the slots into the nozzle chamber occurs assisting in the ejection of ink from the ink ejection port. Preferably, the slots have a substantially constant cross-sectional profile.

In accordance with a farther aspect of the present invention there is provided an ink jet nozzle comprising a nozzle chamber having an ink ejection port in one wall of the chamber, an ink supply source interconnected to the nozzle chamber, an electrostatic actuator comprising a first planar electrode formed within a bottom substrate of the nozzle chamber and a moveable second planar electrode arranged above the first planar electrode, wherein the second planar electrode is moveable to a pit-firing position adjacent to said first planar electrode, upon fanning a potential difference across the electrodes, thereby causing a corrugated border portion of the second electrode to concertina such that, upon reduction of the potential difference, the corrugated border returns to its quiescent position and thereby causes the ejection of ink from the nozzle chamber.

In accordance with a fArther aspect of the present invention there is provided an ink jet nozzle comprising a nozzle chamber having an ink ejection port in one wall of the chamber, an ink supply source interconnected to the nozzle chamber, an electrostatic actuator to eject ink from the nozzle chamber via the ink ejection port, wherein the electrostatic actuator comprises a first planar electrode formed within a bottom substrate of the nozzle chamber and a mnoveable second planar electrode arranged above the first planar electrode, and the ink jet nozzle arrangement is being formed from the depositing and etching of material on a single monolithic wafer. Further, there is an air gap between the first and second planar electrode which is interconnected to an external atmosphere at a side of the nozzle chamber such that air flows into and out of the gap upon movement of the actuator. Preferably the surface of the electrodes facing and opposing electrode are coated with a material having a low coefficient of friction so as to reduce the possibilities of stiction. Advantageously this material comprised of substantially polytetrafluoroethylene. The second planar electrode includes preferable a layer of stiffening materials for maintaining the stiffliess of the second planar electrode wbich is substantially comprised of nitride. The air gap between a first and a second planar electrode structure is farmed by utilisation of a sacrificial material layer which is etched away to release the second planar electrode structure.

Further an outer surface of the ink chamber includes a plurality of etchant holes provided so as to allow a more rapid etching of sacrificial layers during construction.

In accordance with a further aspect of the present invention there is provided an ink jet nozzle comprising a nozzle chamber having an ink ejection port in one wall of the chamber, an ink supply source interconnected to the nozzle chamber, an electrostatic actuator comprising a series of conductive parallel plates interleaved with a resiliently compressible material to eject ink from the nozzle chamber via the ejection port and a method comprising the steps of producing a potential difference across the plates so as to att=c adjacent plates to one another and thereby causing the compressible material to resiliently yield and further reducing the potential difference such that the compressible material returns to its quiescent state, thereby resulting in the ejection of ink from the ejection port.

The resilient yielding of the compressible material results in ink being drawn into the nozzle chamber by means of surface tension effects around the ink ejection port.

In accordance, with a second aspect of the present invention, there is provided an ink jet nozzle comprising a nozzle chamber having an ink ejection port in one wall of the chamber, an ink supply source intercnnected to the nozzle chamber, an electrostatic actuator, which comprises a series of conductive parallel plates interleaved with a resiliently compressible material, to eject ink from the nozzle chamber via the ink ejection port and a control means SUBSTITUT SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/00548 4 for producing a potential difference across the plates so that the material is resiliently, such thA upon deactivation, the electrostatic actuator causes ink to be ejected via the ink ejection port. Advantageously the compressible material comprises a material having a high dielectric constant, such material including piezo electric; electrostrictive or materials which can be switched between a ferro-electric and an anti-ferro-clectric phase. Advantageously the S electrostatic actuator is constructed utilizing semi-conductor fabrication techniques by laying down one planar layer at a time so as to form an initial sandwiched preform, and subsequently selectively etching the preform so as to provide for an electrical interconnect to the conductive parallel plates. Further groups of the series of the conductive parallel plates are constructed from different materials so as to allow for the selective etching of the plates so as to divide them into 2 groups of different polarities during operation. The plates from each group are interconnected to a common conductive portion for the provision of a charge to the conductive plates. Advantageously, the plates are constructed utilizing chemical vapor deposition techniques. The outer surface of the nozzle chamber of the ink jet nozzle includes a plurality of etchant boles provided so as to allow a more rapid etching of sacrificial layers during construction.

In accordance with a further aspect of the present invention there is provided an ink jet printing nozzle apparatus with a connected ink supply chamber, the apparatus comprising an ink ejection means having one surface in fluid communication with the ink in the nozzle chamber, a recoil means connected to the ink ejection means and a first actuator means connected to the ink ejection means.

The method of ejecting ink from the ink chamber can comprise the steps of activation of the first actuator means which drives the ink ejection means from a quiescent position to a pre-firing position and deactivation of the first actuator means, causing the recoil means to drive the ink ejection means to eject ink from the nozzle chamber through the ink ejection port. Further, the recoil means can include a resilient member and the movement of the first actuator results in resilient movement of this recoil means and the driving of the ink ejection means can comprise the resilient member acting upon the ink ejection means. Preferably, the first actuator means can comprise an electromagnetic actuator and the recoil means comprises a torsional spring. The ink ejection means and the first actuator can be interconnected in a cantilever arrangemnent wherein small movements of the first actuator means result in larger movements of the ink ejection means, Advantageously, the recoil means is located substantially at the pivot point of the cantilever construction, The first actuator can include a solenoid coil surrounded by a magnetic actuator having a first mixed magnetic pole and a second moveable magnetic pole, such that, upon activation of the coil, the poles undergo movement relative to one another with the moveable magnetic pole being connected to the actuator side of the cantilever construction. Preferably, the moveable magnetic pole includes a plurality of slots for the flow of ink through the pole upon movement. The ink ejection mecans can comprise a piston or plunger or having a surface substantially mating with at least one surface of the nozzle chamber.

In accordance with a further aspect of the present invention there is provided an ink jet nozzle arrangement having an ink ejection port for the ejection of ink comprising a nozzle chamber interconnected to the ink ejection port and having one moveable wall including an electromagnetic coil, and the nozzle chamber is in a magnetic field such that, upon activation of the electromagnetic coil the moveable wall experiences a tbrce and is caused to move so as to result in the ejection of ink from the nozzle chamber via the ink ejection port.

Further, the moveable wall can be caused to pivot upon activation and interconnects the nozzle chamber with an ink supply chamber and the nozzle chamber is refilled from the ink supply chamber upon the ejection of ink.

4 0 Preferably the moveable wall is interconnected to the nozzle chamber wall by a resilient means. The resilient means SUBSTITUT SHEET (Rule 26) (ROIAU) WO 99/03680 WO 9903680PCT/AU98/00548 acts to return the moveable walk to a quiescent position upon deactivation of the electromagnetic coil.

Advantageously, the electromagnetic coil includes multiple layers substantially comprised of copper. Further, the ink jet nozzle can be in a magnetic, permanent field, which is provided by neodymium iron boron magnets.

In accordance with a further aspect of the present invention there is provided an ink jet printing nozzle apparatus comprising a nozzle chamber in fluid communication with an ink chamber and utilized for the storage of ink to be printed out by the nozzle apparatus, the nozzle chamber having a nozzle chamber outlet hole for the ejection of ink from the nozzle chamber, a magnetic piston located over an aperture in the nozzle chamber and an activation coil located adjacent to the magnetic piston, so that upon activation by a current, force is applied to the piston sufficient to cause movement of the piston from a first position to a second position, this movement causing ink within the nozzle chamber to be ejected from the nozzle chamber through a nozzle chamber outlet hole onto a print media.

Further, the printing nozzle apparatus can comprise a series of resilient means attached to the magnetic piston so as to return the magnetic piston to the first position upon deactivation of the activation coil. Preferably, the resilient means comprises at least one torsional spring.

The ink jet nozzle apparatus is constructed utilizing semi conductor fatbrication techniques, and the magnetic piston and/or coils are constructed from a dual damnascene process. Advantageously, the nozzle chamber outlet hole includes a nozzle rim adapted to reduce hydrophilic surface spreading of the ink. Preferably, the activation coil is constructed from a copper deposition proces and the magnetic piston is constructed from a rare earth magnetic material.

Further, the resilient means in the ink jet printing nozzle apparatus can be constructed from silicon nitride.

In accordance with an aspect of the present invention there is provided an ink jet nozzle comprising an ink reservoir containing an ink supply under an oscillating pressure, a nozzle chamber having an ink ejection port for the ejection of ink drops onto a print media, and a shutter means intercnnecting the reservoir and the nozzle chamber, which is operable by means of electromagnetic actutation so as to control the ejection of ink from the ejection port.

In one embodiment the actuation can comprise activating an electromagnet so as to move an ann interconnected to at least one end of the shutter means, thereby opening a channel for the flow of ink, followed by maintaining a lower keeper current so as to maintain the channel in an open state, followed by deactivation of the electromagnet, and the subsequent returning of the shutter to a closed position. Preferably the electromagnet includes a first and second end, wherein each of the ends are positioned closely adjacent to the arm and the electromagnetic actuation includes movement of the arm closer to both of the ends. Further, the arm is pivoted between the first and second end of the electromagnet, and the electromagnet has a spiral shape.

Advantageously, the ink jet print nozzle includes a resilient means connected to the shutter means which is elastically deformed by the electromagnetic actuation and operates to return to an initial state upon deactivation of the shutter means so as to restrict the further flow of fluid from the ink reservoir to the nozzle chamber.

Preferably the resilient means can include a coiled spring. The ink jet print nozzle is formed utilizing semiconductor fabrication techniques from a copper coil surrounding a soft metal core- The copper coil can be formed from utilizing a Damascene process. Preferably the shutter means comprises a series of moveable slats, moveable over an aperture in the wall of the nozzle chamber.

In accordance with a furither aspect of the present invention. there is provided a method of ejecting ink from an ink jet print nozzle comprising utilizing an electromagnetically activated shutter to control the flow of ink into a SUBSTITUTE SHEET (Rule 26) (RQ/AU) r WO "9/03680 PCT/AU98/00548 6 nozzle chamber such that ink is ejected from the nozzle chamber when the shutter is open utilizing a first high pressure cycle of a pressurised ink supply for the ejection of the ink, a low pressure cycle for the separation of the ejected drop from the ink in the nozzle chamber and a second high pressure cycle of the presstised ink supply for refilling the nozzle chamber with ink.

In accordance with a further aspect of the present invention there is provided an ink jet nozzle comprising a nozzle chamber having an ink ejection port for the ejection for the ejection of ink from the nozzle chamber, an ink supply reservoir for supplying ink to the nozzle chamber and a magnetic actuator located between the nozzle chamber and the ink supply reservoir which is actuated to eject ink by means of externally supplied magnetic pulse cycles.

Further, the ink jet nozzle comprises a part of an array of nozzles and each of the nozzles further comprises a blocking means, for blocking movement of the magnetic actuator for those nozzles of which it is desired not to eject ink from the nozzle chambers in a current magnetic pulse cycle. Preferably the blocking means comprises a thermal actuator having a moveable end protuberance which is moveable to a position blocking the path of movement of the magnetic actuator. The magnetic actuator can include an end protuberance designed to engage the blocking means upon movement of the actuator. Advantageously the magnetic actuator is affixed to an adjacent wall of the nozzle chamber by means. of two bendable strip portions which allow bending movement of the magnetic actuator upon activation by the externally supplied magnetic pulse cycles.

Further the thermal actuator can comprise substantially two arms affixed to a substrate, a first arm having a thin serpentine stmucture encased in a material having a high coefficient of thermal expansion and a second arm comprising a thicker ann having a tapered thin portion near the end connecting to the substrate so as to concentrate any bending of the thermal actuator at a point close to the substrate. The blocking means can be located in a cavity having a low degree of fluid flow through the cavity and preferably, the serpentine arm of the thernal actuator is located alongside an inner wall of dhe cavity.

The ink jet nozzle is constructed via fabrication of a silicon wafer utilizing semi-conductor fabrication techniques. Advantageously, the actuators include a silicon nitride covering as required so as to insulate and passivate them from adjacent portions. Further the nozzle chambers can be formed from high density low pressure plasma eching of the silicon substrate.

In accordance with a further aspect of the present invention theme is provided an ink jet nozzle comprising a nozzle chamber having an ink ejection port at one wall of the chamber, a fixed electric coil located within the chamber or within a wall of the chamber and a moveable plae, in which embedded is an electric coil, located close to the fixed electric coil such that when the amount of current passing through set coils are altered, the movable plunger plate undergoes corresponding movement towards or away from the fixed electric coil and wherein the movement is utilized to inject ink from the nozzle chamber via the ink injection port.

Further, the ink jet nozzle can comprise spring means connected to the moveable plate wherein the moveable plate goes from a quiescent position to a spring loaded position upon activation of the coils and upon deactivation of the coils the spring means causes the moveable coil to retumn to its quiescent position and to thereby eject ink from the ink ejection port Preferably, the fixed electric coil of the moveable plunger plate comprises a stacked multi level spiral of conductive material and the stacked conductive material is interconnected at a central axial point of the spiral. The coils are electrically connected together to form a combined circuit.

Further, the spring means comprises torsional springs attached to the moveable coil and a conductive strip contact to the coils is located within the torsional springs. Advantageously, the coil comprises substantially copper SUBSTITUT SHEET7 (Rule 26) (110/AU) WO 99/03680 PCT/AU9S/00548 7 and is formed from utilization of a damascene construction. The nozzle can be constructed utilizing a sacrificial etch to release the structure of the moveable coil. Prerferably, the nozzle chamber includes a salies of slots within the walls of the nozzle chamber so as to allow the supply of ink to the nozzle chamber and an outer surface of the nozzle chamber includes a series of small etched holes for the etching of any sacrificial layer utilized in the construction of the ink jet print nozzle.

In accordance with a further aspect of the present invention there is provided a means of ejecting ink from a nozzle chamber utilizing the electro-magnetic forces betwee two coils embedded into place to cause movement of at least one of the plates, the movement further causing the consequential ejection of ink from the nozzle chamber.

Further, the utilization of electra-magnetic force comprises using the electro-magnetic force between coils embedded into a moveable and a fixed plate so that the moveable plate moves closer to the fixed plate, the moveable plate further being connected to a spring which upon the movement stores energy within the spring such as that upon deactivation of a current through the coilI, the spring releases its stored energy to thereby cause the movement of the mnoveable plate so as to cause the ejection of ink from the nozzle.

In accordance with a further aspect of the present invention, an ink jet nozzle arrangement is presented comprising: a nozzle chamber having an ink ejection port for the ejection of ink, an ink supply reservoir for supplying ink to the nozzle chamber, a plunger located within the nozzle chamber and further, a linear stepper actuator interconnected to the plunger and adapted to actukat the plunger so as to cause the ejection of ink from the ink ejection port. At least one surface of the plunger located alongside a wall of the nozzle chamber is hydrophobic.

Preferably, the linear actuator interconnected to the plunger in the jet nozzle chamber is driven in three phases by a series of electromagnets. Preferably, a series of twelve electromagnets is arranged in opposing pairs alongside the linear actuator, Further, each phase is duplicated resulting in four electromagnets for each phase. The ink jet nozzle has an open wail along a back surface of the plunger which comprises a series of posts adapted to form a filter to filter ink flowing through the open wail into the nozzle chamber. The linear actuator construction includes a guide at the end opposite to the nozzle chamber for guiding the linear actuator.

In accordance with a further aspect of the present invention there is provided an ink jet nozzle comprising a nozzle chamber having an ink ejection port for the ejection of ink from the nozzle chamber, an ink supply reservoir for supplying ink to the nozzle chamber, a shutter for opening and closing a fluid passage between the reservoir and chamber so as to cause the ejection of ink from the ink ejection port and the shutter includes a ratcheted edge for moving the shutter to an open or closed position via the utilization of an actuator driven driving means. Further, the driving means can include a gearing means interconnected to a driving means wherein the gearing means results in a reduced driving frequency of she ratcheted edge relative to the frequency of operation of the driving means.

Preferably, the driving means includes utilizing a conductive element in a magnetic field to exert a force on the ratcheted edge and utilizing a conductive element in a magnetic field to exert a force on a cog of a gearing mechanism with the gearing mechanism utilized to transfer the force on the ratcheted edge. Advantageously, the conductive element includes a concertinaed structure designed to expand or contract upon movement of the conductive element.

The shutter mechanism can include a series of slots having corresponding retainers utilized in guiding the shutter between the reservoir and the nozzle chamber and the shutter is formed through the fabrication of an array of nozzles on a silicon wafer structure. Preferably, the ink within the ink supply reservoir is driven with an oscillating ink pressure.

In accordance wish a further aspect of the present invention, there is provided an ink jet nozzle comprising a SUBSTITUTE SHEET (Ride 26) (RO/AU) WO 99/03690 PCT/AU98/00548 8 nozzle chamber having an ink ejection port for the ejection of ink from the nozzle chamber, an ink supply reservoir for supplying ink to the nozzle chamber, and a tapere magnetic plunger locate bte n enzzle chamnber and the ink supply reservoir, which is surrounded by an electromagnetic device such that upon activation of the device the magnetic plunger is forced towards the ink ejection Port to thereby cause the ejection of ink from the ink ejection port.

Preferably the plunger is substantially circular and has a tapered rim at adjacent portions of the electromagnetic device. The electromagnetic device is of a cylindrical shape and the plunger is located in the Centre of the cylinder. Advantageously, the plunger is further connected to a resilient means which allows for the return of the plunger to its original position upon deactivation of the electromagnetic device. The magnetic plunger is connected to a side wall of the nozzle chamber by means of a series of springs which radially spiral out to the side wails. Preferably the springs are formed from tensional release of a deposited material. Further the deposited material can include nitride.

In accordance with a tithr aspect of the present invention there is provided a shuttered grill ink jet printer, wherein the shutter is electromagnetically actuated from a closed to an open position so as to allow the ejection from a chamber onto print media.

In accordance with a far-ther aspect of the present invention there is provided a shuttered ink jet nozzle comprising an ink chamber having an ink ejection nozzle for the ejection of ink from the ink chamber, an ink reservoir for the supply of ink to the ink chamber under pressure, and a shutter device located between the ink reservoir and the ink chamber so as to allow or restrict the flew of ink between the ink chamber and ink reservoir to thereby cause the ejection of ink from the chamber, wherein the shutter device is being actuated on demand.

Further the actuator can comprise an electromagnetic coil mechanism attracting a magnetic bar. Preferably the coil is anchored to a wafer and the magnetic bar is connected to a shutter plate adapted to open and close over a series of shutter holes allowing fluid communication between the ink reservoir and the ink chamber, Advantageously the shuttered ink jet nozzle can comprise an actuator that includes at least one linear spring so as to amplify the travel of a shutter plate covering shutter holes upon activation of the actuator. The linear spring is anchored on one side of 23 the ink chamber and the electromagnetic coil is anchored to an opposite side of the ink chamber with a shutter plate operable between the linear spring anchor and the electromagnetic anchor. Preferably the ink reservoir includes ink under oscillating ink pressure. The shutter device can comprise a plurality of shutter plates covering a corresponding plurality of shutter holes allowing the flow of ink between the ink chamber and the ink reservoir. Further the ink chamber can be formed by a crystallographic etch of a silicon wafer. The ejection firequency of drops from the nozzle chamber can be substantially half the frequency of an oscillating pressure of the ink within the ink reservoir.

Advantageously, arrays of ink jet nozzles are grouped into separate groups and each group is activated in turn so as to reduce pressure requirements in the ink jet reservoir.

In accordance with a further aspect of the present invention there is provided a method of operation of a shuttered ink jet print nozzle having a nozzle chamber and ink reservoir, the ink reservoir having an oscillating ink pressure, comprising opening the shutter to cause ink to be ejected from the nozzle chamber resulting in a reduction of ink in the nozzle chamber, followed by leaving the shutter open during a subsequent high pressure of the ink pressure so as to allow the nozzle chamber to refill, followed by closing the shutter at the end of a high pressure cycle so as to restrict back flow of ink from the nozzle chamber to the ink reservoir.

In accordance with a further aspect of the present invention, an ink jet print nozzle arrangement is presented comprising an ink ejection chamber having an ejection port for the ejection of ink, which is in fluid communication SUBSTrrUT SHEET (Rule 26) (RO/ALJ) WO 99/03680 PCT/AU98M548 with an ink reservoir for the supply of ink to be ejected, where at least one wall of the chamber comprises a nmoveable diaphragm actuated by means of a Lorenz force so as to cause the consequential ejection of ink from the ejection chamber. The moveable diaphragm can be of a corrugated or concertinsed form and includes an embedded conductive coil. Upon actuation of the diaphragm by the Lorenz interaction between a current in the conducted coils and a static magnetic field, the diaphragm is expandable by a concertina action. Preferably, the diaphragm is formed through utilization of an appropriately half-toned mask. The ink chamber in the ink jet print nozzle can be formed by means of an isotropic etch of a silicon wafer.

In accordance with a btrber aspect of the present invention there is provided an ink jet nozzle utilizing the phase transformation of a magnetostrictive material in a magnetic field as an actuator to cause the ejection of ink from IGC the chamber. Further, the method can include a magnetostrictive petal in a quiescent state which transforns to art ink ejection state upon the application of a magnetic field thereby causing ink ejection from the chamber Preferably the magnetic field is applied by means of passing a current through a conductive coil adjacent that magnetostrictive material. The ink chamber is formed from a crystallographic etch of the silicon wafer so as to have one surface of the chamber substantially formed by the actuator, which is attached to one wall of the chamber opposite the nozzle port from which ink is ejected. Advantageously, the nozzle port is formed by the back etching of a silicon wafer to a buried epitaxial layer and etching a nozzle port hole in the epitaxial layer. Further the crystallographic etch includes providing side-wall slots of non-etched layers of a processed silicon wafer so as to extend the dimensions of the chamber as a result of the crystallographic etch proess. Preferably the magnetostrictive shape memory alloy comprises substantially Terfanol-D.

In accordance with a further aspect of the present invention there is provided an ink jet nozzle arrangement comprising a nozzle chamber having an ink ejection port in one wall of the chamber, an ink supply source interconnected to the nozzle chamber, an electrostatic actuator to eject ink from the nozzle chamber via the ink ejection port, and a magnetic field actuation means for producing a magnetic field around the magnetostrictive actuator so as to cause magnetostrictive operation of the actuator, thereby causing the actuator to eject ink from the ink ejection port. Preferably the magnetic field actuation means comprises a conductive coil surrounding the magnetostrictive actuator. Further the ink jet nozzle arrangement can be formed on a silicon wafer utilizing semniconductor processing techniques and the conductive coil is interconnected to a lower metal layer which provides control circuitry for the ink jet printer.

In accordance with a fuirther aspect of the present invention there is provided a method of ejecting ink from a chamber comprising utilization of the transformation of a shape memory alloy fr-om its niartensitic phase to its austenitic phase (or visa versa) as an actuator to cause the ejection of ink from the chamber. Further, the actuator can comprise a conductive shape memory alloy panel in a quiescent state which transforms to an ink injection state upon heating thereby causing ink ejection from the chamber. Preferably, the heating occurs by means of passing a current through the shape memory alloy. The chamber can be formed from a crystallographic etch of a silicon wafer so as to have one surface of the chamber substantially formed by the actuator. Advantageously, die actuator is formed from a conductive shape memory alloy arranged in a serpentine form and is attached to one nill of the chamber opposite a nozzle port from which ink is ejected. Further, the nozzle port can be formed by the back etching of a silicon wafer to the epitaxial layer and etching a nozzle port hole in the epitaxial layer. The crystallographic etch can include providing side wall slots of non-etched layers of a processed silicon wafer so as to the extend the dimensions of the chamber as a result of the crystallographic etch process. Preferably, the shape memory alloy comprises nickel SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 WO 9903680PCT/AU98/00548 titanium alloy.

In accordance with a ftunher aspect of the present invention, there is provided an ink jet nozzle arrangewmt for the ejection of ink from an ink ejection nozzle comprising: a substrate; a conductive coil formned on the substrae and operable in a controlled manner, a moveable magnetic actuator surrounding the conductive coil and fonning an ink nozzle chamber between the substrate and the actuator, the moveable magnetic actuator further including an ink ejection nozzle defined therein; wherein variations in the energization level of the conductive coil cause the magnetic actuator to move from a first position to a second position, thereby cawsing a consequential ejection of ink from the nozzle chamber as a result of fluctuations in the ink pressure within the nozzle chamber.

The arrangement can further include an ink supply channel interconnecting the nozzle chamber for the resupply of ink to the nozzle chamber. The interconnection can comprise a series of elongated slots etched in the substrate. The substrate can comprise a silicon wafer and the ink supply channel can be etched through the wafer.

The moveable magnetic actuator can be moveable from a first position having an expanded nozzle chamber volume to a second position having a contracted nozzle chamber volume by the operation of the conductive coil. The arrangement can fimbher include at leas one resilient member attached to the moveable magnetic actuator, so as to bias the moveable magnetic actuator, in its quiescent position, at the first position. The at least one resilient member can comprise a leaf spring.

A slot can be defined between the magnetic actuator and the substrate and the actuator portions adjacent the slot can be hydaphobically treated so as to minimize wicking through the slot.

A magnetic base plate located between the conductive coil and the substrate such that the magnetic actuator and the nozzle plate substantially encompasses the conductive coil. The magnetic actuator can be formed from a cobalt nickel iron alloy.

IJM Coosistory Clauses In accordance with a further aspect of the present invention, there is provided a method of manufacturing a radiant plunger ink jet print head wherein an array of nozzles are formed on a substrate utilizing planar monol ithic deposition, lithographic and etching processes. Preferably, multiple ink jet heads are formed simultaneously on a single plana substrate such as a silicon wafer.

The print heads can be fanned utilizing standard vlsi/uhsi processing and can include integrated drive electronics Conned on the same substrate. The drive electronics preferably being of a CMOS type. In the final construction, ink can be ejected from the substrate substantially normal In accordance with a further aspect of the present invention, there is provided a method of manufacture of an ink jet print head arrangement including a series of nozzle chambers, the method comprising the steps of:, utilizing an initial semiconductor wafer having an electrical circuitry layer and a buried epitaxial layer fonned thereon on; (b) etching a nozzle chamber cavity in the wafer the etching stopping substaintially at the epitaxial layer, depositing and etching a first layer having a high saturation flux density on the electrical circuitry layer to define a first magnetic plate; depositing and etching an insulating layer on the first layer and the electrical circuitry layer, the etching including etching vias for a subsequent conductive layer, depositing and etching a conductive layer on the insulating layer in the form of a conductive coil conductively interconnected to the first layer depositing and etching a sacrificial material layer in the region of the first magnetic plate and the coil, the etching including defining apertures for a series of spring posts; depositing and etching a second layer having a high saturation flux density SUBSTIUTE SHEET (Rule 26) (RO/AU) WO 99103680 WO 9903680PCT/AU98/00548 11 so as form an interconnected second magnetic plate, series of attached springs and spring posts; (hi) etching the back of the wafer to the epitaxial layer, etching an ink ejection nozzle through the epitaxial layer interconnected with the nozzle chamber cavity; and GJ) etching away any remaining sacrificial layers.

The step fairther can comprise etching cavities defining a series of spring posts and the step preferably can include forming a series of leaf springs interconnected with the first magnetic plate for resiliently biasing the magnetic plate in a first direction. The conductive layer can comprise substantially copper.

The etching of layers preferably can include etching yins so as to allow for the electrical interconnection of portions of subsequently layers.

The magnetic flux material can comprise substantially a cobalt nickel iron alloy and the wafer can comprise a double side polished CMOS wafer.

The steps are preferably also utilized to simultaneously separate the wafer into separate printheads.

In accordance with a further aspect of the present invention, there is provided a method of manufacturing an electrostatic ink jet primt head wherein an array of nozzles are formed on a substrate utilizing planar monolithic deposition, lithographic and etching processes. Preferably, multiple ink jet heads are formed simultaneously on a single planar substrate such as a silicon wafer.

The print heads can be fonned utilizing standard visi/ulsi processing and can include integrated drive electronics fonned on the same substrate. The drive electronics preferably being of a CMOS type. In the final construction, ink can be ejected from the substrate substantially normal In accordance with a further aspect of the present invention, there is provided a method of manufacture of an ink jet print bead arrangement including a series of nozzle chambers, the method comprising the steps ofi utilizing an initial semiconductor wafer having an electrical circuitry layer formed theren on; forming a bottom electrode layer of conductive material on or in the electrical circuitry layer, depositing and etching a first hydrophobic layer on the electrode layer, depositing and etching a first sacrificial layer of sacrificial material on the first hydrophobic layer, depositing and etching a top electrode layer of conductive material on the first sacrificial layer the top electrode layer including predetermined portions interconnecting with the electrical circuitry layer; depositing and etching a membrane layer on the top electrode layer, depositing and etching a second sacrificial layer on the membrane layer, the second sacrificial layer forming a blank for the nozzle chamber walls; depositing and etching an inert material layer on the second sacrificial layer so as to fbrm the nozzle chamber walls surrounding the nozzle chamber in addition to a nozzle fluid ejection hole interconnecting with the nozzle chamber, etching an ink supply channel interconnecting with the nozzle chamber etching away the sacrificial layers so as to leave an operational device The top electrode layer and the membrane layer can include a concertina edge so as to allow for movement of the membrane layer. The bottom electrode layer can be forned from a metal plane layer of the circuitry layer.

The ink supply channel can be formed by etching a channel from the back surface of the wafer. The step (h) preferably can include etching a nozzle rim around the nozzie fluid ejection hole and a series of small holes in at least one wall of the nozzle chamber. The hydrophobic layer can comprise substantially polytetrafiuroethylene.

The steps are preferably also utilized to simultaneously separate the wafer into separate printheads In accordance with a fuirther aspect of the present invention, there is provided a method of manufacturing a stacked electrostatic ink jet print head wherein an array of nozzles are formed on a substrate utilizing planar monolithic deposition, lithographic and etching processes. Preferably, multiple ink jet heads are formed SUBSTITUTE SHEET (Rule 26) (RO/AU;) WO 99/03680 PCTIAU98100548 12 simultaneous ly on a single planar substrate such as a silicon wafer.

The print heads can be formed utilizing standard vlsilulsi processing and can include integrated drive electronics formed on the same substrate. The drive electronics preferably being of a CMOS typ. In the final construction, ink can be ejected from the substrate substantially normal to the substrate.

In accordance with a ftirther aspect of the present invention, there is provided a method of manufacture of an ink jet print head arrangement including a series of nozzle chamnbers, the method comprising the steps of: utilizing an initial semiconductor wafe-r having an electrical circuitry layer thereon on including etched vias for interconnection of the circuitry with subsequent layers; repeatedly depositing a series of planar layers on the electrical circuitry layer the planer layers including a first conductive layer, a second conductive layer and an intermediate compressible non conductive layer, etching the planar layer so as to frmn a series of stacked alternating structures; isolating at least one first edge of a stacked alternating structure, eching the second conductive layer and the intermediate compressible layer along the edge so as to expose the first conductive layer, isolating a second edge of the stacked alternating structure; etching the first conductive layer and the intermediate compressible layer along the second edge so as to expose the second conductive layer, (hi) depositing and etching a third conductive layer having first portions interconnected along the first edge to the first conductive layer and a second portions interconnected along the second edge to the second conductive layer, the first and second portions being interconnected to corresponding portions in the electrical circuitry layer; depositing and etching a sacrificial material layer on the wafer, the etching firming a mould for a subsequent nozzle chamber layer; depositing and etching an inert material layer over the sacrificial layer so as to form a nozzle chiamber surrounding the conductive layers in addition to an ink ejection hole; etching an ink supply channel through portions of the wafer to interconnect with the nozzle chamber, and (1) etching away the sacrificial material layer.

The step 3) preferably can include etching a series of small boles in a wall of the nozzle chamber interconnecting the chamber with the ambient atmosphere. The first conductive layer and the second conductive layer are preferably formed from different conductive material. The compressible layer can comprise substantially elastomer. The method further preferably can include swelling the elastomer along the edges The ink supply channel can be etched through the wafer from a back surface of the wafer.

In accordance with a further aspect of the present invention, there is provided a method of manufactring a reverse spring level ink jet print head wherein an array of nozzles are formed on a substrate utilizing planar monolithic deposition, lithographic and etching processes. Preferably, multiple ink jet heads are formed simultanieously on a single planar substrate such as a silicon wafer.

The print heads can be formed utilizing standard visi/ulsi processing and can include integrated drive electronics formed on the same substrate. The drive electronics preferably being of a CMOS type- In the fina] construction, ink can be ejected from the substrate substantially normal In accordance with a further aspect of the present invention, there is provided a method of manufacture of an ink jet print head arrangement including a series of nozzle chambers, the method comprising the steps of: utilizing an initial semiconductor wafer having an electrical circuitry layer and a buried epitaxial layer formed thereon on; (b)i etching a nozzle chamber cavity in the wafer the etching stopping substantially at the epitaxial layer depositing and etching a first layer having a high saturation flux density on the electrical circuitry layer to define a first magnetic plate; depositing and etching an insulating layer on the first layer and the electrical circuitry layer, the etching SUBSTITUTE SHEET (Rule 26) (ROAU) WO 99/03680 PCT/AU98/00548 13 including etching vias for a subsequent conductive layer depositing and etching a conductive layer on the insulating layer in the firm of a conductive coil conductively interconnected to the first layer; (0 depositing and etching a sacrificial mateia layer in the region of dhe first magnetic plate and the coil, the etching including defining apertures for a series of spring posts, a lever arm and interconnected nozzle paddle; depositing and etching a second layer having a high saturation flux density so as form an interconniected second magnetic plate, a lever arm attached to a nozzle paddle and a series of spring posts around which the lever arm pivots; etching the back of the wafer to the epitvcial layer; etching an ink ejection nozzle through the epitaxial layer interconnected with the nozzle chamber cavity; and 0) etching away any remaining sacrificial layers.

The step flurther can comprise etching cavities defining a series of spring posts and the step preferably 0 can include forming a series of torsional pivot springs interconnected with the lever arm for resiliently biasing the second magnetic plate substantially against the first magnetic plate.

The conductive layer can comprise substantially copper and the magnetic flux material can comprise substantially a cobalt nickel iron alloy.

The etching of layers preferably can include etching vias so as to allow for the electrical interconnection of portions of subsequently layers.

The steps are preferably also utilized to simultaneusly separate the wafer into separate printheads.

In acordance with a further aspect of the present invention, there is provided a method of manufacturing a paddle type ink jet print head wherein an array of nozzles are formed on a substrate utilizing planar monolithic deposition, lithographic and etching processes. Preferably, multiple ink jet heads are formed simultaneously on a single planar substrate such as a silicon wafer.

The print heads can be formed utilizing standard vlsilulsi processing and can include integrated drive electronics formed on the same substrate. The drive electronics preferably being of a CMOS type. In the final construction, ink can be ejected from the substrate substantially normal to the substrate.

In accordance with a further aspect of the present invention, there is provided a method of manufacture of an inkjet print head arrangement including a series of nozzle chambers, the method comprising the steps of; utilizing an initial semiconductor wafer having an electrical circuitry layer and a buried epitaxia layer formed thereon on, in addition to a top protecting layer having a series of vies interconnected to predetermined portions of the circuitry layer. forming on the semiconductor wafer layer a first conductive layer including a first conductive coil interconnected to predetermined portions of the circuitry layer depositing and etching, on the first conductive layer, a non-conductive layer including predetermined vias for the interconnection of subsequent layers with lower layers; forming a second conductive layer on the nonconducting layer, including a second conductive coil and the interconnection of predetermined portions of the coil with the first conductive coil and the circuitry layer; (e) depositing and etching a second non-conductive layer over the second conductive layer the etching including etching a series of slots in the second non-conductive layer, etching a series of slots through the first and second nonconductive layers, die first and second conductive layers so as to define a nozzle paddle; etching the semiconductor wafer under the nozzle paddle so as to define a nozzle chamber; back etching the semiconductor wafer to the epitaxial layer, and etching the epitaxiul layer to define a nozzle ejection hole therein interconnecting with the nozzle chamber The step can comprise a crystallographic etch and can utilize the epitaxiul layer as an etch stop.

SUBSTITT SHEET (Rule 26) (3Q/AU) WO 99/03680 WO 9903680PCTIAU98100548 14 The step preferably can include etching a series of small bales in a wall of the nozzle chamber interconnecting the chamber with the ambient atmosphere.

The first conductive layer and the second conductive layer are preferably fanned from substantially copper.

The steps are preferably also utilized to simultanteously separate the wafer into separate printheads.

In accordance with a further aspect of the present invention, there is provided a method of manufacturing a permanent magnet electromagnetic ink jet print head wherein an armay of nozzles are formed on a substrate utilizing planar monolithic deposition, lithographic and etching processes. Preferably, multiple ink jet heads are fanned simultaneously on a single planar substrate such as a silicon wafer.

The print heads can be formed utilizing standard visi/ulsi processing and can include integrated drive electronics forned on the same substrate. The drive electronics preferably being of a CMOS type. In the final construction, ink can be ejected from the substrate substantially normal to the wafer.

In accordance with a further aspect of the present invention, there is provided a method of manufacture of an ink jet print head arrangement including a series of nozzle chambers, the method comprising the steps of: utilizing an initial semiconductor wafer having an electrical circuitry layer and a buried epitaxial layer formed thereon on; (b) depositing and etching a first inert layer, the etching including etching predetermined vies and a nozzle chamber aperture; forming a first conductive coil layer on the first inert layer around the nozzle aperture, the conductive coil layer including predetermined portions interonnecting with the electrical circuitry layer; utilizing the nozzle aperture to etch a nozzle chamber in the wafer, depositing and etching a sacrificial material layer over the wafer including the nozzle chamber, the etching including etching a series a mould for a series of magnet suspension posts and a permanent magnet above the nozzle aperture; deposit and etch a magnetic material layer, the magnetic material layer forming a permanent magnet above the nozzle aperture; deposit and etching an inert material layer interconnecting the permanent magnet to a series of spring pasts in a resilient manner; back etching the wafer substantially to the buried epitaxial layer,~ etching a nozzle fluid ejection aperture through the buried epitaxial layer, etching away the sacrificial layer.

The conductive coil layer can be farmed by first depositing and etching a sacrificial layer forming a mould for the conductive coil layer. The conductive coil layer can be formed utilizing chemical mechanical planarization and can comprise substantially copper.

The first inert layer can comprise substantially silicon nitride.

In accordance with a fur-ther aspect of the present invention, there is provided a method of manufacturing a planar swing grill electromagnetic ink jet print head wherein an array of nozzles are formed on a substrate utilizing planr monolithic deposition, lithographic and etching processes. Preferably, multiple ink jet heads are formed simultaneously on a single planar substrae such as a silicon wafer.

The print heads can be fanned utilizing standard vlsi/ulsi processing and can include integrated drive electronics formed on the same substrate. The drive electronics preferably being of a CMOS type. In the final construction, ink can be ejected fronm the substrate substantially normal to the substrate.

In accordance with a further aspect of the present invention, there is provided a method of manufacture of an ink jet print head arrangement including a series of nozzle chambers, the method comprising the steps of: utilizing an initial semiconductor wafer having an electrical circuitry layer and a buried epitaxial layer formed thereon on; (b) etching a nozzle chamber apertre in the electrical circuitry layer interconnected with a nozzle chamber in the SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 WO 9903680PCT/AU98/00548 semiconductor wafer, depositing a first sacrificial layer filling the nozzle chamber; depositing and etching an inert material layer including a grill structure over the nozzle chamber aperture and vias for electrical interconnection of subsequent layers with the electrical circuitry layer depositing and etching a first conductive material layer including a lower electrical coil portion interconnected 'with the electrical circuitry layer, depositing and etching an inert material layer over the first conductive material layer, the inert material layer including predetermined vias for interconnection of the first conductive material layer 'with subsequent layers; depositing and etching a second sacrificial layer including etching a mould for a fixed magnetic pole, a pivot, a series of springs and spring posts; (h) depositing and etching a high saturation flux nmaterial layer to form the fixed magnetic pole, the pivot, an interconnected shutter grill lever arm and the springs and spring posts; depositing and etching a second inert material layer over the high saturation flux material layer including predetermined vias for interconnection of lower layers with subsequent Layers; U) depositing and etching a second conductive material layer including a side electrical coil portion interconnected with the first conductive material layer, depositing and etching a third conductive material layer including a top electrical coil portion interconnected with the side conductive material layer; (1) depositing and etching a top inert material layer as a corrosion barrier; (nm) back etching the wafer to the epitaxial layer; etching a nozzle aperture in the epitaxial layer, and etching away the sacrificial layers.

The steps further can include the simultaneous formation of a shutter grill guard Mround the shutter.

The epitaxia layer can be utilized as an etch stop in the step which can comprise a crystallographic etch of the wafer.

The conductive layers can comprise substantially copper and the inert layers can comprise substantially silicon nitride.

In accordance with a further aspect of the present invention, there is provided a method of manutctring a pulse magnetic field ink jet print head wherein an array of nozzles are formed on a substrate utilizing planar monolithic deposition, lithographic and etching processes. Preferably, multiple ink jet heads are formed simultaneously on a single planar substrate such as a silicon wafer.

The print heads can be formed utilizing standard vlsi/ulsi processing and can include integrated drive electronics formed on the same substrate. The drive electronics preferably being of a CMOS type. In the final construction, ink can be ejected from the substrate substantially normal In accordance with a further aspect of the present invention, there is provided a method of manufacturing a two plate reverse firing electromagnetic ink jet print head wherein an army of nozzles are formed on a substrate utilizing planar monolithic deposition, lithographic and etching processes. Preferably, multiple ink jet heads are formed sinmultaneously on a single planar substrate such as a silicon wafer.

The print heads can be formed utilizing standard vtsi/ulsi processing and can include integrated drive electronics formed on the same substrate. The drive electronics preferably being of a CMOS type. In the final construction, ink can be ejected from the substrate substantially normal tothe substrate.

In accordance with a further aspect of the present invention, there is provided a method of manufacture of an ink jet print head arrangement including a series of nozzle chambers, the methiod comprising the steps of: utilizing an initial semiconductor wafer having an electrical circuitry layer formed thereon on; depositing and etching a first lower fixed coil layer of conductive material having predetermined interconnections with the electrical circuitry layer; depositing and etching a first protective layer over the fixed coil layer, depositing and etching a second SUBSTITUTE SHEET (Rule 26) (ROIAU) WO 99/03680 PCTIAU98/00548 16 moveable coil layer of conductive material having predetermined intceonnections with the electrical circuitry layer, depositing and etching a second protective layer over the second inoveable coil layer; depositing and etching a sacrificial material layer over the second moveable coil layer, depositing and etching an inert material over the sacrificial material layer to f-rm a nozzle chamber around the first and second coil layer, etching an ink supply channel interconnected with the nozzle chamber, etching away the sacrificial material.

The method further preferably includes the step of forming a hydrophobic layer between the first and second coil layer.

The first and second coil layers are preferably formed in an inert material layer and are formed utilizing a dual danmascene process.

The ink supply channel can be formed by etching a channel from the back surface of the wafer with the step (hi) preferably including etching a series of small holes in at least one wall of the nozzle chamber.

The hydrophobic layer can comprise substantially polytetrfluroethylene. Further, the method can include the step of depositing corrosion barriers over portions of the arrangement so as to reduce corrsion effects.

The wafer can comprise a double side polished CMOS wafer.

1S The steps are preferably also utilized to simultaneously separate the wafer into separate printtieads.

in accordance with a further aspect of the present invention, there is provided a method oftmanufacturing a linear stepper actuator ink jet print head wherein an array of nozzles are formed on a substrate utilizing planar monolithic deposition, lithographic and etching processes. Preferably, multiple ink jet heads are formed simultaneously on a single planar substrate such as a silicon wafer.

The print heads can be tonmed utilizing standard vlsilulsi processing and can include integrated drive electronics formed on the same substrate. The drive electronics preferably being of a CMOS type. In the final construction, ink can be ejected from the substrate substantially normal to the substrate.

in accordance with a further aspect of the present invention, there is provided a method of manufacture of an ink jet print head arrangement including a series of nozzle chambers, the method comprising the steps of: utilizing an initial semiconductor wafer having an electrical circuitry fbrmed theren on; depositing and etching a first sacrificial layer forming a lower electrical coil mould; depositing and etching a first conductive material layer including a lower electrical coil portion interconnected with the electrical circuitry layer, depositing and etching an inert material layer over the first conductive material layer, the inert material layer including predetermined vias for interonnection of the first conductive material layer with subsequent layers; depositing and etching a second sacrificial layer including etching a mould for a fixed magnetic pole, a series of moving poles, horizontal guides and a core pusher rod; (hi) depositing and etching a high saturation flux material layer to form the fixed magnetic pole, the series of moving poles, the horizontal guides and the core pusher rod; depositing and etching a second inert material layer over the high saturaion flux material layer including predetermined vias for interconnection of lower layers with subsequent layers; depositing and etching a second conductive material layer including a side electrical coil portion interconnected with the first conductive material layer; depositing and etching a third conductive material laer including a top electrical coil portion interconnected with the side conductive material layer~ (1) depositing and etching a hydrophobic material layer to form a plunger element surrounding the core pusher rod; (m) depositing and etching a third sacrificial material layer to form a nozzle chamber mould; depositing and etching a third layer of inert material around the plunger elemrent forming a nozzle chamber; etching an ink supply channel to the nozzle chamber; etching away the sacrificial layers.

SU13STITUTE SHEET (Rule 26) (ROt'AU) WO 99103680 PCT/AU98/00W 17 The conductive layers can comprise substantially copper and the inert layers can comprise substantially silicon nitride. The hydrophobic layer can comprise substantially polytetrafluroethylene. The wafer can comprise a double side polished CMOS wafer.

in accordance with a further aspect of the present invention, there is provided a method of manufacturing aprint head wherein an array of nozzles are formed on a substrate utilizing planar monolithic deposition, lithographic and etching processes. Prefrably, multiple ink jet heads are fonmed simultaneously on a single planar substrate such as a silicon water.

The print heads can be formed utilizing standard vlsi/ulsi processing and can include integrated drive electronics formed on the same substrate. The drive electronics preferably being of a CMOS type. In the final construction, ink can be ejected from the substrate substantially normal In accordance with a farther aspect of the present invention, there is provided a method of manufacturing a tapered magnetic pole electromagnetic ink jet print head wherein an array of nozzles are formed on a substrae utilizing planar monolithic deposition, lithographic and etching processes. Preferably, multiple ink jet heads are formed simultaneously on a single planar substrae such as a silicon wafer.

The print heads can be formed utilizing standard visi/ulsi processing and can include integrated drive electronics formed on the same substrate. The drive electronics preferably being of a CMOS type. In the final construction, ink can be ejected fom the substrate substantially normal to the substrate.

in accordance with a farther aspect of the present invention, there is provided a method of manufacture of an ink jet print head arrangement including a series of nozzle chambers, the method comprising the steps of: utilizing an initial semiconductor wafer having an electrical circuitry layer and a buried epitaxial layer formed thereon on; (b) etching a nozzle chamber cavity in the wafer the etching stopping substantially at the epitaxial layer; filling the nozzle chamber cavity with a first sacrificial material layer, depositing and etching a first layer having a high saturation flux density on the electrical circuitry layer to define a first magnetic plate; depositing and etching an insulating layer on the first layer and the electrical circuitry layer, the etching including etching vias for a subsequent conductive layer, depositing and etching a conductive layer on the insulating layer in the form of a conductive coil conductively interconnected to the first layer, depositing and etching a sacrificial material Layer in the region of the first magnetic plate and the coil; (ht) depositing and etching a second layer having a high saturation flux density so as form a second magnetic plate over the nozzle chamber surrounded by an annulus; depositing and etching an inert material layer interconnecting the magnetic plate and the annulus in a resilient manner; U) etching the back of the wafer to the epitaxial layer- etching an ink ejection nozzle through the epitaxial layer interconnected with the nozzle chanter cavity; and (kc) etching away any remaining sacrificial layers.

The conductive layer can comprise substantially copper, the magnetic flux material can comprise substantially a cobalt nickel iron alloy and the inert material can comprise silicon nitride.

The method can also include the step of depositing corrosion barriers over portions of the arrangement so as to reduce corrosion effects.

The second magnetic plate preferably can include a tapered portion adjacent the nozzle chamber.

SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCTIAU98/00548 The steps are preferably also utilized to simultaneously separate the wafer into separate printheads.

In accordance with a further aspect of the present invention, there is provided a method of manufacturing a linear spring electromagnetic grill ink jet print head wherein an array of nozzles are formed on i substrate utilizing planar monolithic deposition, lithographic and etching processes. Preferably,- multiple ink jet heads are formed simultaneously on a single plana substrate such as a silicon wafer.

The print heads can he fanned utilizing standard vLsi/ulsi processing and can include integrated drive electronics Conned on the same substrate. The drive electronics preferably being of a CMOS type. In the final construction, ink can be ejected from the substrate substantially normal to the substrate.

In accordance with a further aspect of the present invention, there is provided a method of manufacture of an ink jet print head arrangement including a series of nozzle chambers, the method comprising the steps of: utilizing an initial semiconductor wafer having an electrical circuitry layer and a buried epitaxia layer formed thereon on; (bn) etching a nozzle chamber apertue in the electrical circuitry layer interconnected with a nozzle chamber in the semiconductor wafer; depositing a first sacrificial layer filling the nozzle chamber; depositing and etching an inert material layer including a grill structure over the nozzle chamber aperture and vias for electrical interconnection of subsequent layers with the electrical circuitry layer, depositing and etching a first conductive material layer including a series of lower electrical coil portions interconnected with the electrical circuitry layer depositing and etching an inert material layer over the first conductive material layer, the inert material layer including predetermined vias for interconnection of the first conductive material layer with subsequent layers; depositing and etching a second sacrificial layer including etching a mould for a solenoid, a fixed magnetic pole, and a linear spring anchor, depositing and etching a high saturation flux material layer to form the series of fixed magnetic poles, a linear spring, the l inear spring anchor and an interconnected shutter grill; depositing and etching a second inert material layer over the high saturation flux material layer including predeternined vias for interconnection of lower layers with subsequent layers; depositing and etching a second conductive material layer including side electrical coil portions surrounding the series of fixed magnetic poles interconnected with the first conductive material layer, (k) depositing and etching a third conductive material layer including a top electrical coil portion interconnected with the side conductive material layer, depositing and etching a top inert material layer as a corrosion barrier, (in) back etching the wafer to the epitaxial layer, etching a nozzle aperture in the epitaxial layer, and etching away the sacrificial layers.

The epitaxia layer can be utilized as an etch stop in the step which can comprise a crystallographic etch of the wafer, The high saturation flux material can comprise substantially a cobalt nickel iron alloy and the conductive layers can comprise substantially copper with the inert layers comprising substantially silicon nitride.

The steps are preferably also utilized to simultaneously separate the wafer into separate printheadt- In accordance with a fiuther aspect of the present invention, there is provided a method of manuftcturing a Lorenz diaphragm electromagnetic ink jet print head wherein an array of nozzles are formed on a substrate utilizing planar monolithic deposition, lithographic and etching processes. Preferably, multiple ink jet heads are formed simultaneously on a single plana substate such as a silicon wafer.

The print heads can be formed utilizing standard vlsi/ulsi processing and can include integrated drive electronics formed on the same substrate. The drive electronics preferably being of a CMOS type. In the final construction, ink can be ejected from the substrate substantially normal to the substrae.

SUBSTITIUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCTIAU98/00548 19 In accordance with a further aspect of the present invention, there is provided a method of manufacture ofan ink jet print head arrangement including a series of nozzle chambers, the method comprising the steps of. utilizing an initial semiconductor wafer having an electrical circuitry layer and a buried epitaxial layer formed thereon on; (b) etching a nozzle chamber cavity in the wafer the etching stopping substantially at the epitaxial layer-, depositing and etching a first layer of sacrificial material, filling the nozzle chamber cavity, the etching including etching a series of concertinaed ridges in the sacrificial layer above the nozzle chamber cavity; depositing and etching a first inert material layer on the concertinaed ridges, the first inert material layer retaining a series of concertined ridges on the surface thereof, depositing and etching a first conductive material layer over the concertinead ridges of the first inert material layer to form a coil layer having a series of concertianed wire portions over the nozzle cavity; (d) depositing and etching a second inert material layer on the first conductive material layer, the second first inert material layer retaining a series of concertined ridges on the surface thereof, etching the back of the wafer to the epitaxial layer, etching an ink ejection nozzle through the epitaxial layer interconnected with the nozzle chamber cavity; and etching away any remaining sacrificial layers.

The inert material layers can comprise substantially silicon nitride and the conductive layer can comprise substantially copper.

In accordance with a further aspect of the present invention, there is provided a method of manufacturing a PTFE surface shooting shuttered oscillating pressure ink jet print head wherein an array of nozzles are formed on a substrate utilizing planar monolithic deposition, lithographic and etching processes. Preferably, multiple ink jet heads are formed simultaneously on a single planar substrate such as a silicon wafer.

The print heads can be formed utilizing standard vlsi/ulsi processing and can include integrated drive electronics formed on the same substrate. The drive electronics preferably being of a CMOS type. In the final construction, ink can be ejected from the subsate substantially normal to the substrate.

In accordance with a further aspect of the present invention, there is provided a method ofmanufacture of an ink jet print head arrangement including a series of nozzle chambers, the method comprising the steps of: utilizing an initial semiconductor wafer having an electrical circuitry layer formed thereon on; etching a nozzle inlet hole in the electrical circuitry layer, depositing and etching a first sacrificial material layer over the electrical circuitry layer including filling the nozzle inlet hole, the etching including etching an actuator anchor area in the first sacrificial material layer, depositing and etching a first expansion material layer of a material having a high coefficient of thermal expansion, the etching including etching predetermined vias in the first expansion material layer; (e) depositing and etching a first conductive layer on the first expansion material layer, the first conductive material layer being conductively interconnected to the electrical circuitry layer via the vias; depositing and etching a second expansion material layer of a material having a high coefficient of thermal expansion, the etching including forming a moveable paddle element from the combination of the first and second expansion material layers and the first conductive layer;, depositing and etching a second sacrificial material layer, the etching forming a nozzle chamber mould; depositing and etching an inert material layer over the sacrificial material layer so as to form a nozzle chamber around the moveable paddle, the etching including etching a nozzle ejection aperture in the inert material 4 C layer; etching an ink supply channel through the wafer, and 0) etching away the sacrificial layers.

SUBSTITU SHEET (Rule 26) (RO/AU) WO 99/03680 WO 9903680PCT/AU9S/00548 The step preferably can include etching a series of sma holes in the inert material layer.

The first and second expansion material layers can comprise substantially polytetrafiuroethylene and the inert material layer can comprise substantially silicon nitride.

The ink supply channel can be fanned by etching a channel from the back surface of the wafer which can comprise a double side polished CMOS wafer.

In accordance with an aspect of the present invention, there is provided a method of manufacturing a magnetostrictive ink jet print head wherein an array of nozzles are formed on a substrate utilizing planar monolithic deposition, lithographic and etching processes. Preferably, multiple ink jet heads are formed simultaneously on a single planar substrae such as a silicon wafer.

The print heads can be formed utilizing standard visi/ulsi processing and can include integrated drive electronics formed on the same substrate. The drive electronics preferably being of a CMOS type. In the final construction, ink can be ejected from the substrate substantially normal In accordance with an aspect of the present invention, there is provided a method of manufacturing a shape memory alloy print head wherein an array of nozzles are fonned on a substrate utilizing planar monolithic deposition, lithographic and etching processes Preferably, multiple ink jet heads are formed simultaneously on a single planar substrate such as a silicon wafer.

The print heads can be formed tilizing standard visi/ulsi processing and can include integrated drive electronics formed on the same substrate. The drive electronics preferably being of a CMOS type. In the final construction, ink can be ejected from the substrata substantially normal to said substrate.

In accordance with a fiurther aspect of the present invention, there is provided a method of manufacture of an ink jet print head arrangement including a series of nozzle chambers, the method comprising the steps of: utilizing an initial semiconductor wafer having an electrical circuitry layer and a buried epitaxial layer formed thereon on; (b) etching a nozzle chamber in the wafer and the electrical circuitry layer, depositing and etching a layer of sacrificial material, filling the nozzle chamber; depositing and etching a layer of shape memory alloy forming a conductive paddle structure over the nozzle chamber attached to the electrical circuitry layer; back etching the semiconductor wafer to the epitaxial layer etching the epitaxial layer to define a nozzle ejection hole therein interconnecting with the nozzle chamber; etching away the sacrificial layers.

The step utilizes the epitaxial layer as an etch stop and can comprise a crystallographic etch. The shape memory alloy can comprise substantially nitinol.

In accordance with an aspect of the present invention, there is provided a method of manufacture of a Coil Actuated Magnetic Plate Ink Jet Printer print head wherein an array of nozzles are formed on a substrate utilizing planar monolithic deposition, lithographic and etching processes.

Multiple ink jet heads are preferably formed simultaneously on a single planar substrate. The substrate can he a silicon wafer.

The print heads are preferably formed utilizing standard vlsifulsi processing. Integrated drive electronics are preferably formed on the same substrate. The integrated drive electronics can comprise a CMOS process.

Ink can be ejected Brom the substrate substantially normal to the substrate.

SUBSTIUTE SKEET (Rule 26) (ROI AU) WO 99/03680 WO 9903680PCT/AU99/00548 21 In accordance with a further aspect of the present invention, there is provided a method of manufature of an ink jet print head arrangement including a series of nozzle chambers, the method comprising the steps of: utilizing an initial semiconductor wafer having an electrical circuitry layer formed thereon on;, etching series of slots in at least the circuitry layer to define a nozzle cavity inlet; depositing and etching a first layer of magnetic flux material on the electrical circuitry layer to define a first magnetic plate; depositing and etching a insulating layer on the first layer and the electrical circuitry layer, the etching including etching vis fix a subsequent conductive layer, (e) depositing and etching a conductive layer in for form of a conductive coil conductively interconnected to the electrical circuitry layer; (0 depositing and etching a hydrophobic material layer in the region of the conductive coil; depositing and etching a sacrificial material layer in the region of the first magnetic plate and the coil, the etching including defining a cavity for the walls of a nozzle chamber depositing and etching a second layer of magnetic flux material over the sacrificial material so as to substantially enclose the conductive coil; etching away the sacrificial material; etching an ink supply channel through the wafer to form a fluid communication with the nozzle chamber.

The step further can comprise etching cavities defining a series of spring posts and the step preferably can includes forming a series of leaf springs interconnected with the first magnetic plate for resiliently biasing the magnetic plate in a first direction. The conductive layer can comprise substantially copper. The step 0) can comprise a through wafer etch from a back surface of the wafer.

The method can further include the step of depositing corrosion barriers over portions of the arrangement so as to reduce corrosion effects and the etching of layers preferably can includes etching via so as to allow for the electrical interconnection of portions of subsequently layers.

Brief Description of the Drawings Notwithstanding any other forms which may fall within the scope of the present invention, prefered forms of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Fig. I is an exploded perspective view illustrating the construction of a single ink jet nozzle in accordance with an embodiment of the present invention; Fig. 2 is a timing diagram illustrating the operation of an embodiment; Fig. 3 is a cross-sectional top view of a single ink nozzle constructed in accordance with an embodiment of the present invention; Fig. 4 provides a legend of the materials indicated in Fig. 5 to Fig. 2 1; Fig. 5 to Fig. 21 illustrate sectional views of the manufacturing steps in one fbrm of construction of an ink jet printhead nozzle; Fig. 22 is a perspective cross-sectional view of a single ink jet nozzle constructed in accordance with an embodiment Fig. 23 is a close-up perspective cross-sectional view (portion A of Fig. 22). of a single ink jet nozzle constructed in accordance with an embodiment; SUBSTIUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/00548 22 Fig. 24 is an exploded perspective view illustrating the construction of a single ink jet nozzle in accordance with an embodiment; Fig. 25 provides a legend of the materials indicated in Fig. 26 to Fig. 36; and Fig. 26 to Fig. 36 illustrate sectional views of the manufacturing steps in one form of construction of an ink jet printhead nozzle.

Fig. 37 is a perspective view through a single ink jet nozzle constructed in accordance with an embodiment of the present invention; Fig. 38 is a schematic cross-sectional view of the ink nozzle constructed in accordance with an embodiment of the present invention, with the actuator in its quiescent state; Fig. 39 is a schematic cross-sectional view of the ink nozzle immediately after activation of the actuator.

Fig. 40 is a schematic cross-sectional view illustrating the ink jet nozzle ready for firing; Fig. 41 is a schematic cross-sectional view of the ink nozzle immediately after deactivation of the actuator; Fig. 42 is a perspective view, in part exploded, of the actuator of a single ink jet nozzle constructed in accordance with an embodiment of the present invention; Fig. 43 is an exploded perspective view illustrating the construction of a single ink jet nozzle in accordance with an embodiment of the present invention; Fig. 44 provides a legend of the materials indicated in Fig. 45 to Fig. 58; and Fig. 45 to Fig. 58 illustrate sectional views of the manufacturing steps in one form of construction of an ink jet printhead nozzle.

Fig. 59 is an exploded perspective view illustrating the construction of a single ink jet nozzle in accordance with an embodiment; Fig. 60 is a perspective view, in part in section, of a single ink jet nozzle constructed in accordance with an embodiment; Fig. 61 provides a legend of the materials indicated in Fig. 62 to Fig. 78; and Fig. 62 to Fig. 78 illustrate sectional views of the manufacturing steps in one form of construction of an ink jet printhead nozzle.

Fig. 79 is a cross-sectional view of a single ink jet nozzle constructed in accordance with an embodiment in its quiescent state; Fig. 80 is a cross-sectional view of a single ink jet nozzle constructed in accordance with an embodiment, illustrating the state upon activation of the actuator, Fig. 81 is an exploded perspective view illustrating the construction of a single ink jet nozzle in accordance with an embodiment; Fig. 82 provides a legend of the materials indicated in Fig. 83 to Fig. 93; and Fig. 83 to Fig. 93 illustrate sectional views of the manufacturing steps in one form of construction of an ink jet printhead nozzle.

Fig. 94 is a perspective cross-sectional view of a single ink jet nozzle constructed in accordance with an embodiment; Fig. 95 is an exploded perspective view illustrating the construction of a single ink jet nozzle in accordance with an embodiment; SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 WO 9903680PCT/AU9S/00548 23 Fig. 96 provides a legend of the materials indicated in Fig. 97 to Fig. 11; and Fig. 97 to Fig. Ill illustrate sectional views of the manufabcturing steps in one form of construction of an ink jet printhead nozzle.

F ig. 112 is a perspective view of a single ink jet nozzle constructed in accordance with an embodiment with the shutter means in its closed position; Fig. 113 is a perspective view of a single ink jet nozzle constructed in accordance with an embodiment, with the shutter mean in its open position; Fig. 114 is an exploded perspective view illustrating the construction of a single ink jet nozzle in accordance wMt an embodiment; Fig. 115 provides a legend of the materials indicated in Fig. 116 to Fig. 137; and Fig. 116 to Fig. 137 illustrate sectional views of the manufatcturing steps in one form of construction of an ink jet printhead nozzle.

Fig. 138 is a perspective, partly sectional view of a single ink jet nozzle in its quiescent position constructed in accordance with an embodiment; Fig. 139 is a perspective, partly sectional view of a single ink jet nozzle in its firing position constructed in accordance with an embodiment; Fig. 140 is an exploded perspective illustrating the construction of a single ink jet nozzle in accordance wish an embodiment; Fig. 141 provides a legend of the materials indicated in Fig. 142 to Fig. 156; and Fig. 142 to Fig. 156 illustrate sectional views of the manufacturing steps in one form of construction of an ink jet printhead nozzle.

Fig. 157 is a cross sectional view of a single ink jet nozzle as constructed in accordance with an embodiment in its quiescent state; Fig. 158 is a cross sectional view of a single ink jet nozzle as constructed in accordance with an embodiment after reaching its stop position; Fig. 159 is a cross sectional view of a single ink jet nozzle as constructed in accordance with an embodiment in the keeper face position; Fig. 160 is a cross sectional view of a single ink jet nozzle as constructed in accordance with an embodiment alter dc-energizing from the keeper level.

Fig. 161 is an exploded perspective view illustrating the construction of an embodiment, Fig. 162 is she cut out topside view of a single ink jet nozzle constructed in accordance with an embodiment in the keeper level; Fig. 163 provides a legend of the materials indicated in Fig. 164 to Fig. 183; and Fig. 164 to Fig. 183 illustrate sectional views of the manufacturing steps in one form of construction of an ink jet printhead nozzle.

Fig. 184 is acut-out top view of an ink jet nozzle in accordance with an embodiment;, Fig. 185 is an exploded perspective view illustrating she construction of a single ink jet nozzle in accordance wish an embodiment, Fig. 186 provides a legend of the materials indicated in Fig. 187 to Fig. 207; and SUBSTI~TE SHEET (Rule 26) (110/AU) WO 99/03680 PCT/AU9S/00548 24 Fig. 187 to Fig. 207 illustrate sectional views of the manufacturing steps in one form of construction of an ink jet printhead nozzle.

Fig. 208 is a cut-out top perspective view of the ink nozzle in accordance with an embodiment of the present invention; Fig. 209 is an exploded perspective view illustrating the shutter mechanism in accordance with an embodiment of the present invention; Fig. 210 is a top cross-sectional perspective view of the ink nozzle constructed in accordance with an embodiment of the present invention; Fig. 211 provides a legend of the materials indicated in fig. 212 to Fig. 225; and Fig. 212wt Fig. 226 illustrate sectional views of the manufacturing steps in one form of construction of an ink jet printhead nozzle.

Fig. 227 is a perspective cross-sectional view of a single ink jet nozzle constructed in accordance with an embodiment4 Fig. 228 is an exploded perspective view illustrating the construction of a single ink jet nozzle in accordance with an embodiment; Fig. 229 provides a legend of the materials indicated in Fig. 230 to Fig. 248; and Fig. 230 to Fig. 248 illustrate sectional views of the manufacturing steps in one form of construction of an ink jet printhead nozzle.

Fig. 249 is a perspective view of a single ink jet nozzle constructed in accordance with an embodiment, in its closed position; Fig. 250 is a perspective view of a single ink jet nozzle constructed in accordance wit an embodiment, in its open position; Fig. 251 is a perspective, cross-sectional view taking along the line 11 of Fig. 250, of a single ink jet nozzle in accordance with an embodiment Fig. 252 is an exploded perspective view illustrating the construction of a single ink jet nozzle in accordance with an embodiment; Fig. 253 provides a legend of the materials indicated in Fig. 254 to Fig. 275;- and Fig. 254 to Fig. 275 illustrate sectional views of the manufacturing steps in one form of construction of an ink jet prinihead nozzle.

Fig. 276 is a schematic top view of a single ink jet nozzle chamber apparatus constructed in accordance with an embodiment; Fig. 277 is a top cross-sectional view of a single ink jet nozzle chamber apparatus with the diaphragm in its activated stage; Fig. 278 is a schematic cross-sectional view illustrating the exposure of a resist layer through a halftone mask; Fig. 279 is a schematic cross-sectional view illustrating the resist layer after development exhibiting a corrugated pattern; Fig. 280 is a schematic cross-sectional view illustrating the transfer of the corrugated pattern onto the substrate by etching; SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/00549 Fig. 281 is a schematic cross-sectional view illustrating the construction of an embedded, corrugated, conduction layer,~ and Fig. 282 is an exploded perspective view illustrating the construction of a single ink jet nozzle in accordance with an embodiment.

Fig. 283 is a perpective view of the heater races used in a single ink jet nozzle constructed in accordance with an embodiment Fig. 284 provides a legend of the materials indicated in Fig. 285 to Fig. 2%6; and Fig. 285 to Fig. 2%6 illustrate sectional views of the manuficturing steps in one form of construction of an ink jet printhead nozzle.

Fig. 297 is a perspective cross-sectional view of a single ink jet nozzle constructed in accordance with an embodiment; Fig. 298 is an exploded perspective view illustrating the construction of a single ink jet nozzle in accordance with an embodiment Fig. 299 provides a legend of the materials indicated in Fig. 300 to Fig. 311; and Fig. 300 to Fig. 311 illustrate sectional views of dhe manufacturing steps in one form of construction of an ink jet printhead nozzle.

Fig. 312 is an exploded perspective view of a single ink jet nozzle as constructed in accordance with an embodiment; Fig. 313 is a top cross sectional view of a single ink jet nozzle in its quiescent state taken along line A-A in Fig. 312; Fig. 314 is a top cross sectional view of a single ink jet nozzle in its actuated state taken along line A-A in Fig. 3 12; Fig. 315 provides a legend ofxthe materials indicated in fig. 316 to Fig. 326; and Fig. 316 to Fig. 326 illustrate sectional views of the manufacturing steps in one form of construction of an ink jet prinihead nozzle.

Fig. 327 to Fig. 329 are schematic illustrations of the operation of ant ink jet nozzle arrangement of an embodiment.

Fig. 330 illustrates a side perspective view, pertly in section, of a single ink jet nozzle arrangement of an embodiment; Fig. 331 provides a legend of the materials indicated in Fig. 332 to Fig. 347; Fig. 332 to Fig. 347 illustrate sectional views of the manufacturing steps in one lbrni of construction of an ink jet printhemi nozzle; Description of the Preferred and Other Embodiments The preferred embodiments and other embodiments will be discussed under separate headings with the heading including an Ii number for ease of reference. The headings also include a type designator with T indicating thermal, S indicating shutter typ and F indicating a field type.

Description of IJ01 F In Fig. 1, there is illustrated an exploded perspective view illustrating the construction of a single ink jet nozzle 4 in accordance with the principles of the present invention.

SUBSTITUE SHEET (Rule 26) (110/AU) WO "103680 PCT/AU98/00548 26 The nozzle 4 operates on the principle Of electro-mechanical energy conversion and comprises a solenoid 11I which is connected electrically at a first end 12 to a magnetic plate 13 which is in turn connected to a current source e.g. 14 utilized to activate the ink nozzle 4. The magnetic plate 13 can be constructed from ekectrically conductive iron.

A second magnetic plunger 15 is also provided, again being constructed from soft magnetic iron. Upon energizing the solenoid 11, the plunger IS is attracted to the fixed magnetic plate 13. Thie plunger thereby pushes against the ink within the nozzle 4 creating a high pressure zone in the nozzle chamber 17. This causes a movement of the ink in the nozzle chamber 17 and in a first design, subsequent ejection of an ink drop. A series of apertures e.g.

is provided so that ink in the region of solenoid I11 is squirted out of the holes 20 in the top of the plunger 15 as it moves towards lower plate 13. This prevents ink trapped in the area of solenoid I11 from increasing the pressure on the plunger 15 and thereby increasing the magnetic forces needed to move the plunger Referring now to Fig. 2, there is illustrated 30 a timing diagram of the plunger current control signal.

Initially, the solenoid current is activated 31 for the movement of the plunger and ejection of a drop from the ink nozzle. After approximately 2 micro-seconds, the current to the solenoid is tuirned off. At the same time or at a slightly later time 32, a reverse current is applied having approximately half the magnitude of the forward current. As the plunger has a residual magnetism, the reverse current 32 causes the plunger to move backwards towards its original position. A series of torsional springs 22, 23 (Fig. 1) also assists in the return of the plunger to its original position. The reverse current is turned off before the magnetism of the plunger 15 is reversed which would otherwise result in the plunger being attracted to the fixed plate again. Returning to Fig. 1, the forced return of the plunger 15 to its quiescent position results in a low pressure in the chanter 17. This can cause ink to begin flowing from the outlet nozzle 24 inwards and also ingests air to the chamber 17. The forward velocity of the drop and the backward velocity of the ink in the chamber 17 are resolved by the ink drop breaking off around the nozzle 24. The ink drop then continues to travel toward the recording medium under its own momentum. The nozzle refills due to the surface tension of the ink at the nozzle tip 24. Shortly after the timne of drop break off, a meniscus at the nozzle tip is formed with an approximately a concave hemispherical surface. The surface tension will exert a net forward force on the ink which will result in nozzle refilling. The repetition rate of the nozzle 4 is therefore principally determined by the nozzle refill time which will be lOOmicro- seconds, depending on the dervice geometry, ink surface tension and the volume of the ejected drop.

Turning now to Fig. 3, an important aspect of the operation of the electro-magnetically driven print nozzle will now be described. Upon a current flowing through the coil 11, the plate 15 becomes strongly attracted to the plate 13. The plate 15 experiences a downward force and begins movement towards the plate 13. This movement imparts a momentum to the ink within the nozzle chamber 17. The ink is subsequently ejected as hereinbefore described. Unfortuniately, the movement of the plate 15 causes a build-up of pressure in the area 64 between the plate and the coil 11. This build-up would normally result in a reduced effectiveness of the plate 15 in ejecting ink.

However, in a first design the plate 15 preferably includes a series of apertures e.g. 20 which allow for the flow of ink from the area 64 back into the ink chamber and thereby allow a reduction in the pressure in area 64. This results in an increased eifhctiveniess in the operation of the plat Preferably, the apertures 20 are of a teardrop shape increasing in diameter with increasing radial distance of the plunger. The aperture profile thereby providing minimal disturbance of the magnetic flux through the plunger while maintaining structural integrity of plunger SUBSTITUTE SHEET (Rule 26) (ROIAU) WO 99/03680 WO 9903680PCTIAU9S/00548 27 After the plunger 15 has reached its end position, the current through coil 11I is reversed resulting in a repulsion of the two plates 13, 15. Additionally, the torsional spring emg. 23 acts to return the plate 15 to its initial position.

The use of a torsional spring e.g. 23 has a number of substantial benefits including a compact layout, and the construction of the torsional spring from the same material and samne processing steps as that of the plate In an alternative design, the top surhice of plate 15 does not include a series of apertures. Rather, the inner radial surface 25 of plate 15 comprises slots of substantially constant cross-sectional profile in fluid communication between the nozzle chamber 17 and the area 64 between plate 15 and the solenoid 11. Upon activation of the coil 11, the plate 15 is attracted to the armature plate 13 and experiences a force directed towards plate 13. Msa result of the movement, fluid in the area 64 is compressed and experiences a higher pressure than its surrounds. As a result, the flow of fluid takes place out of the slots in the inner radial surface 25 plate 15 into the nozzle chamber 17. The flow of fluid into chamber 17, in addition to the movement of the plate 15, causes the ejection of ink out of the ink nozzle port 24. Again, the movement of the plate 15 cause the torsional springs, for example 23, to be resiliently deformed.

Upon completion of the movement of the plate 15, the coil ILI is deactivated and a slight reverse current is applied.

1 5 The reverse current acts to repl the plate 15 from the arnature plate 13. The torsional springs, for example 23, act as additional means to return the plate 15 to its initial or quiescent position.

Fabrication Returning now to Fig. 1, the nozzle apparatus is constructed from the following main parts including a nozzle tip 40 having an aperture 24 which can he constructed from boron doped silicon. The radius of the aperture 24 of the nozzle tip is an important deterninant of drop velocity and drop size.

Next, a CMOS silicon layer 42 is provided upon which is fabricated all the data storage and driving circuitry 41 necessary for the operation of the nozzle 4. In this layer a nozzle chamber 17 is also constructed. The nozzle chamber 17 should be wide enough so that viscous drag from the chamber walls does not significantly increase the force required of the plunger. It should also be deep enough so that any air ingested through the nozzle port 24 when the plunger returns to its quiescent state does niot extend to the plunger device. If it does, the ingested bubble may form a cylindrical surface instead of a hemispherical surface resulting in the nozzle not refilling properly. A CMOS dielectric and insulating layer containing various current paths parts for the current connection to the plunger device is also provided 4.

Next, a fixed plate of ferroelectric: material is provided having two parts 13, 46. The two parts 13, 46 are electrically insulated from one another.

Next a solenoid I I is provided. This can comprise a spiral coil of deposited copper. Preferably a single spiral layer is utilized to avoid fabrication difficulty and copper is used for a low resistivity and high electro-rnigration resistance, Next, a plunger 15 of ferromagnetic material is provided to maximize the magnetic force generated. The plunger 15 and fixed magnetic plate 13, 46 surrouind the solenoid I I as a torus. Thus, little magnetic flux is lost and the flux is concentrated around the gap between the plunger 15 and the fix plate 13, 46.

The gap between the fixed plate 13, 46 and the plunger 15 is one of the most important "pails" of the print nozzle 4. The size of the gap will strongly affect the magnetic force generated, and also limits the travel of the plunger 15. A small gap is desirable to achieve a strong magnetic fbrce, but a large gap is desirable to allow longer plunger 15 to travel, and therefore allow smaller plunger radius to be utilized.

SUBSTITUT SHEET (Rule 26) (110/AU) WO 99/Q3680 PCT/AU98/00548 28 Next, the springs, e.g. 22, 23 for returning to the plunger 15 to its quiescent position after a drop has been ejected are provided. The springs, e.g. 22, 23 can be fadicated fom the same material, and in the same processing steps, as the plunger 15. Preferably the springs, e.g. 22, 23 act as torsional springs in their interaction with the plunger Finally, all surfaces are coated with passivation layers, which may be silicon nitride (Si3N 4 diamond like carbon (DLC), or other chemically inert, highly impermeable layer. The passivation layers are especially important for device lifetime, as the active device will be immersed in the ink.

One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer deposit 3 microns of epitaxial silicon heavily doped with boron.

2. Deposit 10 microns of epitaxial silicon, either p-ype or n-type, depending upon the CMOS process used.

3. Complete a 0.5 micron, one poly, 2 metal CMOS process. This step is shown in Fig. 5. For clarity, these diagrams may not be to scale, and may not represent a cross section though any single plane of the nozzle. Fig. 4 is a key to representations of various materials in these manufacturing diagrams, and those of other cross referenced ink jet configurations.

4. Etch the CMOS oxide layers down to silicon or aluminum using Mask 1. This mask defines the nozzle chamber, the edges of the print heads chips, and the vias for the contacts from the aluminum electrodes to the two halves of the split fixed magnetic plate.

5. Plasma etch the silicon down to the boron doped buried layer, using oxide from step 4 as a mask. This etch does not substantially etch the aluminum. This step is shown in Fig. 6.

6. Deposit a seed layer of cobalt nickel iron alloy. CoNiFe is chosen due to a high saturation flux density of 2 Tesla, and a low coercivity. [Osaka, Tetsuya et al, A soft magnetic CoNiFe film with high saturation magnetic flux density, Nature 392, 796-798 (1998)].

7. Spin on 4 microns of resist, expose with Mask 2, and develop. This mask defines the split fixed magnetic plate, for which the resist acts as an electroplating mold. This step is shown in Fig. 7.

8. Electroplate 3 microns of CoNiFe. This step is shown in Fig. 8.

9. Strip the resist and etch the exposed seed layer, This step is shown in Fig. 9.

Deposit 0.1 microns of silicon nitride (Si3N 4 11. Etch the nitride layer using Mask 3. This mask defines the contact vias from each end of the solenoid coil to the two halves of the split fixed magnetic plate.

12. Deposit a seed layer of copper. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistance, which increases reliability at high current densities.

13. Spin on 5 microns of resist, expose with Mask 4, and develop. This mask defines the solenoid spiral coil and the spring posts, for which the resist acts as an electroplating mold. This step is shown in Fig. 14. Electroplate 4 microns of copper.

Strip the resist and etch the exposed copper seed layer. This step is shown in Fig. 11.

16. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated.

SUBSTI SHEET (Rule 26) (RO/AU) WO 99/03680 WO 9903680PCT/AU98/00548 29 17. eposit 0. 1 microns of silicon nitride.

18. Deposit 1 micron of sacrificial material. This layer determines the magnetic gap.

19. Etch the sacrificial material using Mask 5. This mask defines the spring posts. This step is shown in Fig.

12.

20. Depositsa seed layer of CoNiFe.

21. Spin on 4.5 microns of meist, expose with Mask 6, and develop. This mask defines the walls of the magnetic plunger, plus the spring posts. The resist forms an electroplating mold for these parts. This step is shown in Fig. 13.

22. Electroplate 4 microns of CoNiFe. This step is shown in Fig. 14.

23. Deposit aseed layer of CoNiFe.

24. Spin on 4 microns of resist, expose with Mask 7, and develop. This mask defines the roof of the magnetic plunger, the springs, and the spring posts. The resist forms an electroplating mold for these parts. This step is shown in Fig. Electroplate 3 microns of CoNiFe. This step is shown in Fig. 16.

26. Mount the wafer on a glass blank and back-etch the wafer using KOH, with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer. This step is shown in Fig. 17.

27. Plasma back-etch the boron doped silicon layer to a depth of (approx.) I micron using Mask 8. This mask defines the nozzle rim. This step is shown in Fig. 18.

28. Plasma back-etch through the boron doped layer using Mask 9. This mask defines the nozzle, and the edge of the chips. At this stage, the chips are separate, but are still mounted on the glass blank. This step is shown in Fig. 19.

29. Detach the chips from the glass blank. Strip all adhesive, resist, sacrificial, and exposed seed layers. This step is shown in Fig. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colons of ink to the appropriate regions of the front surface of the wafer.

3 1. Connect the print heads to their interconnect systems.

32. 1-ydrophobize the front surface of the print heads.

33. Fill the completed print heads with ink and test themn. A filled nozzle is shown in Fig. 21.

Deeitin or U02 F In an embodiment, an ink jet print head is made up of a plurality of nozzle chambers each having an ink ejection port. Ink is ejected from the ink ejection port through the utilisation of attraction between two parallel plates.

Turning to Fig. 22, there is illustrated a cross-sectional view of a single nozzle arrangement 1 10 as constructed in accordance with an embodiment. The nozzle arrangement 110 includes a nozzle chamber Ill in which is stored ink to be ejected out of an ink ejection port 112. The nozzle arrangement 1 10 can be constructed on the top of a silicon wafer utilising micro electro-mechartical systems construction techniques as will become more apparent hereinafter. The top of the nozzle plate also includes a series of regular spaced etchant holes, e.g.

123 which are provided for efficient sacrificial etching of lower layers of the nozzle arrangement I110 during construction. The size of the etchant holes 113 is small enough that surface tension characteristics prohibit ejection from the holes 113 during operation.

SUBSTITUT SHIEET (Rule 26) (RLO/AU) WO 99/03680 PCTIAU98/00548 Ink is supplied to the nozzle chamber I 11 via an ink supply channel, e.g. 115.

Turning now to Fig. 23, there is illustrated a cross-sectional view of one side of the nozzie arrangement 110. A nozzle arranigement 110 is constructed on a silicon wafer base 117 on top of which is' first constructed a standard CMOS two level metal layer Itl8 which includes the required drive and control circuitry for each nozzle arrangement The layer I118, which includes two levels of aluminium, includes one level of aluminium 119 being utilised as a bottom electrode plate. Other portions of this layer 120 can comprise nitride passivation. On top of the layer 119 there is provided a thin polytetrafluoroethylene (PTFE) layer 12 1, Next, an air gap 127 is provided between the top and bottom layers. This is followed by a further PTFE layer 128 which forms part of the top plate 122. The two PTFE layers 121, 123 are provided so as to reduce possible stiction effects between the upper and lower plates. Next, a top aluminiumn electrode layer 130 is provided followed by a nitride layer (not shown) which provides structural integrity to the top electro plate. The layers 128 130 are fabricated so as to include a corrugated portion 123 which concertinas upon movement of the top plate 122.

By placing a potential difference across the two aluminum layers 119 and 130, the top plate 122 is attracted to bottom aluminum layer 119 thereby resulting in a movement of the top plate 122 towards the bottom plate 119.

This results in energy being stored in the concertinaed spring arrangement 123 in addition to air passing out of the side air holes, e.g. 133 and the ink being sucked into the nozzle chamber as a result of the distortion of the meniscus over the ink ejection port 112 (Fig. 22). Subsequently, the potential across the plates is eliminated thereby causing the concentinaed spring portion 123 to rapidly return the plate 122 to its rest position. The rapid movement of the plate 122 causes the consequential ejection of ink from the nozzle chamber via the ink ejection port 112 (Fig. 22).

Additionally, air flows in via air gap 133 underneath the plate 122.

The ink jet nozzles of an embodiment can be formed from utilisafion of semi-conductor fabrication and MEMS techniques. Turning to Fig. 24, there is illustrated an exploded perspective view of the various layers in the final construcion of' a nozzle arrangement 1 10. At the lowest layer is the silicon wafer 11 7 upon which all other processing steps take place. On top of the silicon layer 117 is the CMOS circuitry layers 118 which primarily comprises glass. On top of this layer is a nitride passivation layer 120 which is primarily utilized to passivate and protect the lower glass layer from any sacrificial process that may be utilized in the building up of subsequent layers.

Next there is provided the aluminum layer 119 which, in the alternative, can form part of the lower CMOS glass layer 118. This layer 119 forms the bottom plate. Next, two PTFE layers 126, 128 are provided between which is laid down a sacrificial layer, such as glass, which is subseqluently etched away so as to release the plate 122 (Fig. 23). On top of the PTFE layer 128 is laid down the aluminum layer 130 and a subsequent thicker nitride layer (not shown) which provides structural support to the top electrode stopping it from sagging or deforming. After this comes the top nitride nozzle chamber layer 135 which forms the rest of the nozzle chamber and ink supply channel. The layer 135 can be tbnned from the depositing and etching of a sacrificial layer and then depositing the nitride layer, etching the nozzle and etchant holes utilizing an appropriate mask before etching away the sacrificial material.

Obviously, print heads can be formed from large arrays of nozzle arrangements 1 10 on a single wafer which is subsequently diced into separat print heads. Ink supply can be either from the side of the wafer or through the wafer utilizing deep anisotropic etching systems such as high density low pressure plasm etching systems available from surface technology system. Further, the corrugated portion 123 can be formed trough the tilisation of a half tone mask process.

SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 991Q3680 WO 993680P/AU98/00548 31 One form of detailed marnificturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer, complete a 0.5 micron, one poly, 2 metal CMOS process. This step is shown in Fig. 26. For clarity, these diagrams may not be to soake, and may not represent a cross section though any single plane of the nozzle. Fig. 25 is a key to representations of various materials in these manufacturing diagrams, and those of other cross referenced ink jet configurations.

2. Etch the passivation layers to expose the bottom electrode, formed of second level metal. This etch is performed using Mask 1. This step is shown in Fig. 27.

3. Deposit 50 nm of MTE or other highly hydrophobic material.

4. Deposit 0.5 microns of sacrificial material, tg. polyimide.

Deposit 0.5 microns of (sacrificial) photosensitive polyimide.

6. Expose and develop the photosensitive polyimide using Mask 2. This mask is a gray-scale mask which defines the concertina edge of the upper electrode. The reult of the etch is a series of triangular ridges at the circumference of the electrode. This concertina edge is used to convert tensile stress into bend strain, and thereby allow the upper electrode to move when a voltage is applied across the electrodes. This step is shown in Fig. 28.

7. Etch the polyimide and passivation layers using Mask 3, which exposes the contacts for the upper electrode which are formed in second level metal, 8. Deposit 0.1 microns of tantalum, fanning the upper electrode.

9. Deposit 0.5 microns of silicon nitride (Si3N 4 which forms the movable membrane of the upper electrode.

Etch the nitride and tantalum using Mask 4. This mask defines the upper electrode, as well as the contacts to the upper electrode. This step is shown in Fig. 29.

11. Deposit 12 microns of (sacrificial) photosensitive polyimide.

12. Expose and develop the photosensitive polyimide using Mask 5. A proximity aligner can be used to obtain a large depth of focus, as the line-width for this step is greater thant 2 microns, and can be 5 microns or more.

This mask defines the nozzle chamber wails. This step is shown in Fig. 13. Deposit 3 microns of PECVD glass. This step is shown in Fig. 3 1.

14. Etch to a depth of I micron using Mask 6. This mask defines the nozzle rim. This step is shown in Fig.

32.

Etch down to the sacrificial layer using Mask 7. This mask defines the roof of the nozzle chamber, and the nozzle itself. This step is shown in Fig. 33.

16. Back-etch completely through the silicon wafer (with, lbr example, an ASE Advanced Silicon Etcher from Surface Technology Systems) using Mask 8. This mask defines the ink inlets which are etched through the wafer. The wafer is also diced by this etch.

17. Back-etch through the CMOS oxide layer through the holes in the wafer. This step is shown in Fig. 34.

18. Etch the sacrificial polyimide. The nozzle chambers are cleared, a gap is formed between the electrodes and the chips are separated by this etch. To avoid stiction, a final rinse using supercooled carbon dioxide can be used. This step is shown in Fig. SUBSTTUrE SHE (Ride 26) (RO/AU) WO 99/03680 PCT/AU9M0548 32 19. Mount the print beads in their pacaginig, which may be a molded plastic framer incorporating ink channels which supply the appropriate color ink to the ink inlets at the back of the wafer.

Connect the print heads to their interconnect systems. For a low profile connection with minimum disruption of airflow, TAB may be used. Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper.

21. Hydrophobize the front surface of the print heads.

22. Fill the completed print heads with ink and test them. A filled nozzle is shown in Fig. 36.

Description or 1.J04 F In arn embodiment, a stacked capacitive actuator is provided which has alternative electrode layers sandwiched between a compressible polymer. Hence, on activation of the stacked capacitor the plates are drawn together compressing the polymer thereby storing energy in the compressed polymer. The capacitor is then deactivated or drained with the result that the compressed polymer acts to return the actuator to its original position and thereby causes the ejection of ink from and ink ejection port.

Turning now to Fig. 37, there is illustrated a single nozzle arrangement 3 10 as constructed in accordance with an embodiment. The nozzle arrangement 310 includes an ink ejection pental 311 for the ejection of ink on demand. The ink is ejected from a nozzle chamber 312 by means of a stacked capacitor-type device 313. In a first design, the stacked capacitor device 313 consists of capacitive plates sandwiched between a compressible polymer.

Upon charging of the capacitive plates, the polymer is compressed thereby resulting in a general "accordion" or "concertinaing" of the actuator 313 so that it's. top surtace moves away from the ink ejection portal 311. The compression of the polymer sandwich stores energy in the compressed polymer. The capacitors are subsequently rapidly discharged resulting in the energy in the compressed polymer being released upon the polymer's return to quiescent position. The return of the actuator to its quiescent position results in the ejection of' ink from the nozzle chamber 312. The process is illustrated schematically in Fig. 38 to Fig. 41, with Fig. 38 illustrating the nozzle chamber 310 in its quiescent or idle state, having an ink mneniscus 314 around the nozzle ejection portal 311.

Subsequently, the electrostatic actuator 313 is activated resulting in its contraction as indicated in Fig. 39- The contraction results in the meniscus 314 changing shape as indicated with the resulting surface tension effects resulting in the drawing in of ik around the meniscus and consequently ink 316 flows into nozzle chamber 312.

After sufficient time, the meniscus 314 returns to its quiescent position with the capacitor 313 being loaded ready for firing (Fig. 40). The capacitor plates 313 ame then rapidly discharged resulting, as illustrated in Fig. 41, in the rapid return of the actuator 313 to it's original position. The rapid return imparts a momentum to the ink within the nozzle chamber 312 so as to cause the expansion ofthe ink meniscus 3l4and the subsequent ejection of ink from the nozzle chamber 312.

Turning now to Fig. 42, there is illustrated a perspective view of a portion of the actuator 313 exploded in part. The actuator 313 consists of a series of interleaved plates 320, 321 between which is sandwiched a compressive material 322, for example styrene-ethylene-butylene-styrenc block co-polymer. One group of electrodes, e.g. 320, 323, 325 jut out at one side of the stacked capacitor layout. A second series of electrodes, e.g. 321, 324 jut out a second side of the capacitive actuator. The electrodes arm connected at one side to a first conductive material 327 and the other series of electrodes, e.g. 321, 324 are connected to second conductive material 328 (Fig. 37). The two conductive materials 327, 32S are electrically isolated from one another and are in turn interconnected to lower signal SUBSTITUTE SKEET (Rule 26) (RO/AC) WO 99/03680 PCT/AU98/00548 33 and drive layers as will become more readily apparent here and after.

In alternative designs, the stacked capacitor device 313 consists of other thin film materials in place of the example styrene-ethylene-butylene.styrene block co-polymer. Such materials may include: I) Piezo electric materials such as PZT 2) Electrostrictive materials such as PLZT 3) Materials, that can be electrically switched between a ferro-electric and an anti-ferro-electric phase such as PLZSnT.

Importantly, the electrode actuator 313 can be rapidly constructed utilizing chemical vapor deposition (CVD) techniques. The various layers, 320, 321, 322 can be layed down on a planer wafer one after another covering the whole surface of the wafer. A stack can be built up rapidly utilizing CVD techniques. The two sets of electrodes are preferably deposited utilizing separate metals. For example, aluminum and tantalum could be utilized as materials for the metal layers. The utilisation of different metal layers allows for selective etching utilizing a mask layer so as to form the structure as indicated in Fig. 42. For example, the CVD sandwich can be first layed down and then a series of selective etchings utilizing appropriate masks can be utilized to produced the overall stacked capacitor structure. The utilisation of the CVD process substantially enhances the efficiency of production of the stacked capacitor devices.

Construction of the Ink Nozzle Arrangement Turning now to Fig. 43 there is shown an exploded perspective view illustrating the construction of a single ink jet nozzle in accordance with an embodiment. The ink jet nozzle arrangement 310 is constructed on a standard silicon wafer 330 on top of which is constructed data drive circuitry which can be constructed in the usual manner such as a two-level metal CMOS layer 331. On top of the CMOS layer 331 is constructed a nitride passivation layer 332 which provides passivation protection for the lower layers during operation an also should an etchant be utilized which would normally dissolve the lower layers. The various layers of the stacked device 313, for example 320, 321, 322, can be layed down utilizing CVD techniques. The stacked device 313 is constructed utilizing the aforementioned production steps including utilizing appropriate masks for selective etchings to produce the overall stacked capacitor structure. Further, interconnection can be provided between the electrodes 327, 328 and the circuitry in the CMOS layer 331. Finally, a nitride layer 333 is provided so as to form the walls of the nozzle chamber, e.g. 334, and posts, e.g. 335, in one open wall 336 of the nozzle chamber. The surface layer 337 of the layer 333 can be deposited onto a sacrificial material. The sacrificial material is subsequently etched so as to form the nozzle chamber 312 (Fig. 37). To this end, the top layer 337 includes etchant holes, 338, so as to speed up the etching process in addition to the ink ejection portal 311. The diameter of the etchant holes, e.g. 338, is significantly smaller than that of the ink ejection portal 311. If required an additional nitride layer may be provided on top of the layer 320 to protect the stacked device 313 during the etching of the sacrificial material to form the nozzle chamber 312 (Fig. 37) and during operation of the ink jet nozzle.

One form of detailed manuficturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer, complete a 0.5 micron, one poly, 2 metal CMOS process. This step is shown in Fig. 45. For clarity, these diagrams may not be to scale, and may not repmsent a cross section though any single plane of the nozzle. Fig. 44 is a key to representations of various materials in these manufacturing diagrams, SUBSTIUTE SHEET (Rule 26) (RO/AU) WO 99/03690 WO 9903480PCTIAU98/00548 34 and those of other cross referenced ink jet configurations.

2. Etch the CMOS oxide layers to second level metal using Mask 1. This mask defines the contact vies from the electrostatic stack to the drive circuitry.

3. Deposit 0.l1 microns of aluminum.

4. Deposit 0. 1 microns of elastomner.

Deposit 0. 1 microns of tantalum.

6. Deposit 0. 1 microns of elastomer.

7. Repeat steps 2 to 5 twenty times to create a stack of alternating metal and elastomer which is 8 microns high, with 40 metal layers and 40 elastonier layers. This step is shown in Fig. 46.

8. Etch the stack using Mask 2. This leaves a separate rectangular multi-layer stack for each nozzle. This step is shown in Fig. 47.

9. Spin on resist 1 expose with Mask 3, and develop. This mask defines one side of the stack. This step is shown in Fig. 48.

Etch the exposed elastomner layers to a horizontal depth of 1 micron.

11, Wet etch the exposed aluminum layers to a horizontal depth of 3 microns.

12. Foam the exposed elastomer layers by 50 nn to close the 0. 1 micron gap left by the etched aluminum.

13. Strip the resist. This step is shown in Fig. 49.

14. Spin on resist, expose with Mask 4, and develop. This mask defines the opposite side of the stack. This step is shown in Fig. 15. Etch the exposed elastomer layers to a horizontal depth of 1 micron.

16. Wet etch the exposed tantalum layers to a horizontal depth of 3 microns.

17. Foam the exposed elastomer layers by 50 nm to close the0.!1 micron gap left by the etched aluminum.

lB. Strip the resist. This step is shown in Fig. 5 1.

19. Deposit 1.5 microns of tantalum. This metal contacts all of the aluminum layers on one side of the stack, and all of the tantalum layers on the other side of the stack.

Etch the tantalum using Mask 5. This mask defines the electrodes at bath edges of the stack. This step is shown in Fig. 52.

2!1. Deposit 18 microns of sacrificial material photosensitive polyimide).

22. Expose and develop the sacrificial layer using Mask 6 using a proximity aligner. This mask defines the nozzle chamber walls and inlet filter. This step is shown in Fig. 53.

23. Deposit 3 microns of PECVD glass.

24. Etch to a depth of 1 micron using Mask 7. This mask defines the nozzle rim. This step is shown in Fig.

54, Etch down to the sacrificial layer using Mask 8. This mask defines the roof of the nozzle chamber, and the nozzle itself. This step is shown in Fig. 26. Back-etch completely through the silicon wafer (with, for example, an ASE Advanced Silicon Etcher from Surface Technology Systemns) using Mask 9. This mask defines the ink inlets which are etched through the wafer. The wafer is also diced by this etch. This step is shown in Fig. 56.

27. Back-etch through the CMOS oxide layer through the holes in the wafer, SUBS-TrUTE SHEET (Rule 26) (RO/AU) WO "103680 PCT/AU98/00548 28. Etch the sacrificial material. The nozzle chambers are cleared, and the chips are separated by this etch.

This step is shown in Fig. 57.

29. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply the appropriate color ink to the ink inlets at the back of the wafer.

30. Connect the print heads to their interconnect systems. For a low profile connection with minimum disruption of airflow, TAB may be used. Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper.

3 1. lHydrophobize the front surface of the print heads.

32. fill the completed print heads with ink and test them. A filled nozzle is shown in Fig. 58.

Description or I05 F An embodiment of the present invention relies upon the utilisation of a magnetic actuator to "load" a spring.

such that, upon deactivation of the magnetic actuator the resultant movement of the spring causes ejection of a drop of' ink as the spring returns to its original position.

Turning to Fig. 59, there is illustrated an exploded perspective view of an ink nozzle arrangement 401 is constructed in accordance with an embodiment, It would be understood that an embodiment can be constructed as an array of nozzle arrangements 401 so as to together form a line for printing.

The operation of the ink nozzle arrangement 401 of Fig. 59 proceeds by a solenoid 402 being energized by way of a driving circuit 403 when it is desired to print out a ink drop. The energized solenoid 402 induces a magnetic field in a fixed soft magnetic pole 404 and a moveable soft magnetic pole 405. The solenoid power is turned on to a maximum current for long enough to move the moveable pole 405 from its rest position to a stopped position close to the fixed magnetic pole 404. The ink nozzle arrangement 401 of Fig. 59 sits within an ink chamber filled with ink.

Therefore, holes 406 are provided in the moveable soft magnetic pole 405 for "squirting" out of ink from around the coil 402 when the plate 405 undergoes movement.

The moveable soft magnetic pole is balanced by a fucrurn 408 with a pisto head 409. Movement of the magnetic pole 405 closer to the stationary pole 404 causes the piston head 409 to move away from a nozzle chamber 411 drawing air into the chamber 411 via an ink ejection port 413. The piston 409 is then held open above the nozzle chamber 411 by means of maintaining a low "keeper" current through solenoid 402. The keeper level current through solenoid 402 being sufficient to maintain the moveable pole 405 against the fixed soft magnetic pole 404. The level of current will be substantially less than the maximum current level because the gap between the two poles 404 and 405 is at a minimum. For example, a keeper level current of 10% of the maximum current level may be suitable.

During this phase of operation the meniscus of ink at the nozzle tip or ink ejection port 413 is a concave hemisphere due to the in flow of air. The surfce tension on the meniscus exerts a net force on the ink which results in ink flow from the ink chamber into the nozzle chamber 411. This results in the nozzle chamber refilling, replacing the volume taken up by the piston head 409 which has been withdrawn. This process takes approximately 100 .ts.

The current within solenoid 402 is then reversed to half that of the maximum current. The reversal demagnetizes the magnetic poles and initiates a return of the piston 409 to its rest position. The piston 409 is moved to its normal rest position by both the magnetic repulsion and by the energy stored in a stressed torsional spring 416.419 which was put in a stat of torsion upon the movement of moveable pole 405.

SUBSTITUTE SHEET (Rule 26) (110/AU) WO 99/03680 WO 9903680PCT/AU98100548 36 The forces applied to the piston 409 as a result of the reverse cunezu and spring 416,419 will be greatest at the beginning of the movement of the piston 409 and will decrease as the spring elastic stress fails to zero. As a result, the acceleration of piston 409 is high at the beginning of a reverse stroke and the resultant ink velocity within the chamber 411 becomes uniforrn during the stroke. This results in an increased operating tolerance before ink flow over the print head surface will occur.

At a predetermined time during the return stroke, the solenoid reverse current is turned off. The current is turnied off when the residual magnetism of the movable pole is at a minimum. The piston 409 continues to move towards its original rest position.

The piston 409 will overshoot the quiescent or rest position due to its inertia. Overshoot in the piston movement achieves two things: greater ejected drop volume and velocity, and improved drop break off as the piston returns from overshoot to its quiescent position.

The piston 409 will eventually return from overshoot to the quiescent position. This return is caused by the springs 416, 419 which are now stressed in the opposite direction. The piston return "sucks" some of the ink back into the nozzle chamber 411, causing the ink ligament connecting the ink drop to the ink in the nozzle chamber 411 to thin. The forward velocity of the drop and the backward velocity of the ink in the nozzle chamber 411 are resolved by the ink drop breaking off from the ink in the nozzle chamber 411.

The piston 409 stays in the quiescent position until the next drop ejection cycle.

A liquid ink print head has one ink nozzle arrangement 401 associated with each of the multitude of nozzles.

The arrangement 401 has the following major parts: Drive circuitry 403 for driving the solenoid 402.

A nozzle tip 413. The radius of the nozzle tip 413 is an important determinant of drop velocity and drop size.

A piston 404. This is a cylinder which moves through the nozzle chamber 411 to expel the ink.

The piston 409 is connected to one end of the lever ann 417. The piston radius is approximately 1.5 to 2 times the radius of the hole 413. The ink drop volume output is mostly determined by the volume of ink displaced by the piston 409 during the piston return stroke.

A nozzle chamber 411. The nozzle chamber 411 is slightly wider than the piston 409. The gap between the piston 409 and the nozzle chamber walls is as nmal as is required to ensure that the piston does not contact the nozzle chamber during actutation or return. If the print heads are fabricated using 0.5 Jpim semiconductor 3 0 lithography, then a I pLrm gap will usually be sufficient. The nozzle chamber is also deep enough so that air ingested through the nozzle tip 413 when the plunger 409 returns to its quiescent state does not extend to the piston 409, [f it does, the ingested bubble may form a cylindrical surface instead of a hemispherical surface. If this happens, the nozzle will not refill properly.

A solenoid 402. This is a spiral coil of copper. Copper is used for its low resistivity, and high electro-migration resistance.

A fixed magnetic pole of ferromaignetic. material 404.

A moveable magnetic pole of ferromagnetic material 405. To maximize the magnetic force generated, the moveable magnetic pole 405 and fixed magnetic pole 404 surround the solenoid 402 as a torus. Thus little magnetic flux is lost, and the flux is concentrated across the gap between the moveable magnetic pole 405 and SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03690 WO 99036S0PCT/AU98/00548 37 the fixed pole 404. The moveable magnetic pole 405 has holes in the surface 4o6 (Fig. 59) above the solenoid to allow trapped ink to escape. These holes are arranged and shaped so as to minimize their effect on the magnetic force generated between the moveable magnetic pole 405 and the fixed magnetic pole 404.

A magnetic gap. The gap between the fixed plate 404 and the moveable magnetic pole 405 is one of the mast important "parts" of the print actuator. The size of the gap strongly affects the magnetic force generated, and also limits the travel of the mnoveable magnetic pole 405. A small gap is desirable to achieve a strong magnetic force. The travel of the piston 409 is related to the travel of the moveable magnetic pole 405 (and therefore the gap) bythe lever arm 417.

Length of the lever arm 417. The lever arm 417 allows the travel of the piston 409 and the moveable magnetic pole 405 to be independently optimized. At the short end of the lever arm 417 is the moveable magnetic pole 405. At the long end of the lever arm 417 is the piston 409. The spring 416 is at the fulcrum 408. The optimum travel for the moveable magnetic pole 405 is less than I micron, so as to minimize the magnetic gap. The optimum travel for the piston 409 is approximately 405 Aim for a 1200 dpi printer. The difference in optimum travel is resolved by.a lever 417 with a 5:1 or greater ratio in arm length.

(10) Springs 416, 419 (Fig. 59). The springs e.g. 416 return the piston to its quiescent position after a deactivation of the actuator. The springs 416 are at the fulcrum 408 of the lever arm.

(11) Passivation layers (not shown). Al surfaces are preferably coated with passivation layers, which may be silicon nitride (Si 3

N

4 diamond like carbon (DLC), or other chemically inert, highly impermeable layer. The passivation layers are especially important for device lifetime, as the active device is immersed in the ink. As will be evident from the foregoing description there is an advantage in ejecting the drop on deactivation of the solenoid 402.

This advantage comes from the rate of acceleration of the moving magnetic pole 405 which is used as a piston or plunger.

The force produced by a moveable magnetic pole by an electromagnetic induced field is approximately proportional to the inverse. square of the gap between the moveable 405 and static magnetic poles 404. When the solenoid 402 is oftf, this gap is at a maximum. When the solenoid 402 is turned on, the moving pole 405 is attracted to the static pole 404. As the gap decreases, die force increases, accelerating the movable pole 405 faster. The velocity increases in a highly non-linear fashion, approximately with the square of time. During the reverse movement of te moving pole 405 upon deactivation the acceleration of the moving pole 405 is greatest at the beginning and then slows as the spring elastic stress fills to zero. As a result, the velocity of the moving pole 405 is more uniform during the reverse stroke movement.

The velocity of piston or plunger 409 is much more constant over the duration of the drop ejection stroke.

The piston or plunger 409 can readily be entirely removed from the ink chamber during the ink fallI stage, and thereby the nozzle filling time can be reduced, allowing faster print head operation.

However, this approach does have some disadvantages over a direct firing type of actuator: The stresses on the spring 416 are relatively large. Careful design is required to ensure that the springs operate at below the yield strength of the materials used.

The solenoid 402 must be provided with a "keeper" current for the nozzle fill duration, The keeper current will1 typically be less thani 10% of the solenoid actuation current. However, the nozzle fill duration is typically around 50 times the drop firing duration, so the keeper energy will typically exceed the solenoid actuation energy.

SUBSITUTE SHIEET (Rule 26) (ROIAU) WO 99/03680 PCT/AU98/00548 38 The operation of the actuator is more complex due to the requirement for a "keeper" phase.

The print head is fabricated from two silicon wafers. A first wafer is used to fabricate the print nozzles (the print head wafer) and a second wafer (the Ink Channel Wafer) is utilized to fabricate the various ink channels in addition to providing a support means for the first channel. The fabrication process then proceeds as follows: Start with a single crystal silicon wafer 420, which has a buried epitaxial layer 422 of silicon which is heavily doped with boron. The boron should be doped to preferably 1020 atoms per cm 3 of boron or more, and be approximately 3 pm thick, and be doped in a manner suitable for the active semiconductor device technology chosen.

The wafer diameter of the print head wafer should be the same as the ink channel wafer.

Fabricate the drive transistors and data distribution circuitry 403 according to the process chosen

CMOS).

Planarise the wafer 420 using chemical Mechanical Planarisation (CMP).

Deposit 5 micron of glass (Sin 2 over the second level metal.

Using a dual damascene process, etch two levels into the top oxide layer. Level t is 4 im deep, and level 2 is 5 p.m deep. Level 2 contacts the second level metal. The masks for the static magnetic pole are used.

Deposit 5 4m of nickel iron alloy (NiFe).

Planarise the wafer using CMP, until the level of the Sin 2 is reached forming the magnetic pole 404.

Deposit 0.1 Jm of silicon nitride (Si3N 4 Etch the Si3N4 for via holes for the connections to the solenoids, and for the nozzle chamber region 4l1.

Deposit 4 n of SiO 2 (11) Plasma etch the Sin 2 in using the solenoid and support post mask.

(12) Deposit a thin diffusion barrier, such as Ti, TN, or TiW, and an adhesion layer if the diffusion layer chosen has insufficient adhesion.

(13) Deposit 4 pin of copper for forming the solenoid 402 and spring posts 424. The deposition may be by sputtering, CVD, or electroless plating. As well as lower resistivity than aluminum, copper has significantly higher resistance to electra-migration. The electro-migration resistance is significant, as current densities in the order of 3 x 106 Amps/cm 2 may be required. Copper films deposited by low energy kinetic ion bias sputtering have been found to have 1,000 to 100,000 times larger electro-migration lifetimes larger than aluminum silicon alloy. The deposited copper should be alloyed and Layered for maximum electro-migration lifetimes than aluminum silicon alloy. The deposited copper should be alloyed and layered for maximum electro-migration resistance, while maintaining high electrical conductivity.

(14) Planarise the wafer using CMP, until the level of the SiO 2 is reached. A damascene process is used for the copper layer due to the difficulty involved in etching copper. However, since the damascene dielectric layer is subsequently removed, processing is actually simpler if a standard deposit/etch cycle is used instead of damascene. However, it should be noted that the aspect ratio of the copper etch would be 8:1 for this design, compared to only 4:1 for a damascene oxide etch. This difference occurs because the copper is 1 gim wide and 4 )1m thick, but has only 0.5 J.m spacing. Damascene processing also reduces the lithographic difficulty, as the resist is on oxide, not metal.

SUBSTITUTE SHEET (Rule 26) (ROIAU) WO 99/03680 PCT/AU98/00548 39 Plasma etch the nozzle chamber 411, stopping at the boron doped epitaxial silicon layer 42 1. This etch will be through around 13 pim of SiO 2 and 8 Jim of silicon. The etch should be highly anisotropic, with near vertical sidewalls. The etch stop detection can be on boron in the exhaust gasses. If this etch is selective against NiFe, the masks for this step and the following step can be combined, and the fiblowing step can be eliminated. This step also etches the edge of the print head wafr down to the boron layer, for later separation.

(16) Etch the SiO2 layer. This need only be removed in the regions above the NiFe fixed magnetic poles, so it can be removed in the previous step if an Si and SiO 2 etch selective against NiFe is used.

(17) Conformably deposit 0.5 pin of high density Si3N4. This forms a corrosion barrier, so should be free of pin-holes, and be impermeable to OH ions.

(18) Deposit a thick sacrificial layer 440. This layer should entirely fill the nozzle chambers, and coat the entire wafer to an added thickness of 8 pin. The sacrificial layer may be Si02.

(19) Etch two depths in the sacrificial layer for a dual damascene process. The deep etch is 8 pm, and the shallow etch is 3 gin. The masks defines the piston 409, the lever arm 417, the springs 416 and the moveable magnetic pole 405.

(20) Conformably deposit 0.1 Lm of high density Si3N4. This forms a corrosion barrier, so should be free of pin-holes, and be impermeable to OH ions.

(21) Deposit 8 pm of nickel iron alloy (NiFe).

(22) Planarise the wafer using CMP, until the level of the SiO 2 is reached.

(23) Deposit 0.1 pim of silicon nitride (Si3N4).

(24) Etch the Si 3

N

4 everywhere except the top of the plungers.

Open the bond pads.

(26) Permanently bond the wafer onto a pre-fabricated ink channel wafer. The active side of the print head wafer faces the ink channel wafer. The ink channel wafer is attached to a backing plate, as it has already been etched into separate ink channel chips.

(27) Etch the print head wafer to entirely remove the backside silicon to the level of the boron doped epitaxial layer 422. This etch can be a batch wet etch in ethylenediamine pyrocatechol (EDP).

(28) Mask the nozzle rim 414 from the underside of the print head wafer. This mask also includes the chip edges.

(31) Etch through the boron doped silicon layer 422, thereby creating the nozzle holes. This etch should also etch fairly deeply into the sacrificial material in the nozzle chambers to reduce time required to remove the sacrificial layer.

(32) Completely etch the sacrificial material. If this material is SiO 2 then a HF etch can be used. The nitride coating on the various layers protects the other glass dielectric layers and other materials in the device from HF etching. Access of the HF to the sacrificial layer material is through the nozzle, and simultaneously through the ink channel chip. The effective depth of the etch is 21 pLm.

(33) Separate the chips from the backing plate. Each chip is now a full print head including ink channels. The two wafers have already been etched through, so the print heads do not need to be diced.

(34) Test the print heads and TAB bond the good print heads.

Hydrophobise the front surface of the print heads.

SUBST1TUTE SHEET (Rule 26) (RO/AU) WO 99/03680 WO 9903680PCT/AU98100548 (36) Perform final testing on the TAB banded print heads.

Fig. 60 shows a perspective view, in part in section, of a single ink jet nozzle arrangement 401 constructed in accordance with an embodiment One alternative firm of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utiliing the following steps: 1. Using a double sided polished wafer deposit 3 microns of epitaxial silicon heavily doped with boron, 2. Deposit 10 microns of epitaxial silicon, either p3-type or n-type, depending upon the CMOS proess used.

3. Complete a 0.5 micron, one poly, 2 mretal CMOS process. This step is shown in Fig. 62. For clarty, thes diagrams may not be to scale, and may not represent a cross section though any single plane of the nozzle. Fig. 61 is a key to representations of various materials in these manufacturing diagrams.

4. Etch the CMOS oxide layers down to silicon or aluminum using Mask 1. This mask defines the nozzle chamber, the edges of the print heads chips, and the vies for the contacts from the aluminum electrodes to the two halves of the split fixed magnetic plate.

5. Plasma etch the silicon down to the boron doped buried layer, using oxide from step 4 as a mask. This etch does not substantially etch the aluminum. This step is shown in Fig. 63.

6. Deposit a seed layer of cobalt nickel iron alloy. CoNiFe is chosen due to a high saturation flux density of 2 Tesla, and a low coercivity. [Osaka, Tersuya et at, A soft magnetic CoNiFe film with high saturation magnetic flux density, Nature 392, 796-798 (1998)].

7. Spin on 4 microns of resist, expose with Mask 2, and develop. This mask defines the split fixed magnetic plate and the nozzle chamber wall, for which the resist act as an electroplating mold. This step is shown in Fig. 64, S. Electroplate 3 microns of CoNiFe. This step is shown in Fig. 9. Strip the resist and etch the exposed seed layer. This step is shown in Fig. 66.

10. Deposit 0. 1 microns of silicon nitride (Si3N 4 11. Etch the nitride layer using Mask 3. This mask defines the contact vies from each end of the solenoid coil to the two halves of the split fixed magnetic plate.

12, Deposit a seed layer of copper. Copper is used for its low resitivity (which results in higher efficiency) and its high electromigration resistance, which increases reliability at high current densities.

13. Spin on 5 microns of resist, expose with Mask 4, and develop. This mask defines the solenoid spiral coil, the nozzle chamber wall and the spring posts, for which the resist acts as an electroplating mold. This step is shown in Fig. 67.

14. Electroplate 4 micrns of copper.

Strip the resist and etch the exposed copper seed layer. This step is shown in Fig. 68.

16. Wafer probe. All electrical connections are complete at this point, band pads are accessible, and the chips are not yet separated.

17. Deposit 0. 1 microns of silicon nitride.

lBa. Deposit I micron of sacrificial material. This layer determines the magnetic gap.

19. Etch the sacrificial material using Mask 5. This mask defines the spring posts and the nozzle chamber wall. This step is shown in Fig. 69.

SUBSTrIUT SHEET (Rule 26) (ROfAU) WO 99/03680 PCT/AU98/00548 41 Deposit a seed layer of CoNiFe.

21. Spin on 4.5 microns of resist, expose with Mask 6, and develop. This mask defines the wails of the magnetic plunger, the lever arm, the nozzle chamber wall and the spring posts. The resist formis an electroplating mold for these parts. This step is shown in Fig. 22. Electroplate 4 microns of CoNiFe. This step is shown in Fig. 71.

23. Deposit a seed layer of CoNi~e.

24. Spin on 4 microns of resist, expose with Mask 7, and develop. This mask defines the roof of the magnetic plunger, the nozzle chamber wail, the lever arm, the springs, and the spring posts. The resist forms an electroplating mold for these parts. This step is shown in Fig. 72.

25. Electroplate 3 microns of CoNiFe. This step is shown in Fig. 73.

26. Mount the wafer on a glass blank and back-etch the wafer using KOH-, with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer. This step is shown in Fig. 74.

27. Plasma back-etch the boron doped silicon layer to a depth of 1 micron using Mask 8. This mask defines the nozzle rim. This step is shown in Fig. 28. Plasma back-etch through the boron doped layer using Mask 9. This mask defines the nozzle, and the edge of the chips. At this stage, the chips are separate, but are still mounted on the glass blank. This step is shown in Fig. 76.

29. Detach the chips from the glass blank. Strip all adhesive, resist, sacrificial, and exposed seed layers. This step is shown in Fig. 77.

30. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer.

3 1. Connect the print heads to their interconnect systems.

32. Hydrophobize the front surface of the print heads.

33. Fill the completed print heads with ink and test themn. A filled nozzle is shown in Fig. 78.

Description of LJ06 F Referring now to Fig. 79, there is illustrated a cross-sectional view of a single ink nozzle unit 510 constructed in accordance with an embodiment. The ink nozzle unit 5SI0 includes an ink ejection nozzle 511 for the ejection of ink which resides in a nozzle chamber 513. The ink is ejected from the nozzle chamber 513 by means of movement of paddle 515. The paddle 5 15 operates in a mnagnetic: field 5 16 which runs along the plane of the paddle 515. The paddle 515 includes at least one solenoid coil 517 which operates under the control of nozzle activation signal. The paddle 515 operates in accordance with the well known principal of dhe force experienced by a moving electric charge in a magnetic field. Hence, when it is desired to activate the paddle 515 to eject an ink drop out of ink ejection nozzle 5 11, the solenoid coil 5 17 is activated. As a result of the activation, one end of the paddle will experience a downward force 519 while the other end of the paddle will experience an upward force 520. The downward forceil19results in acorresponding movement of the paddle and the resultant ejection of ink.

As can be seen from the cross section of Fig. 79, the paddle 5 15 can comprise multiple layers of solenoid wires with the solenoid wires, e.g. 521, forming a complete circuit having the current flow in a counter clockwise direction around a center of the paddle 5 15. Th is results in paddle 5 15 experiences a rotation about an axis through (as illustrated in Fig. 80) the center point the rotation being assisted by means of a torsional spring, e.g. 522, which SUBSITT SHEET (Rule 26) (RO/AU) WO 99/03680 PCIPIAU98/00548 42 ams to return the paddle 515 to its quiescent state after deactivation of the current paddle 515. Whilst a torsional spring 522 is to be preferred it is envisaged that other forms of springs may be possible such as a leaf spring or the like.

The nozzle chamber 513 refills due to the surface tension of the ink- at the ejection nozzle 511 after the ejection of ink.

Manufacturing Constriction Process The construction to the inkjet nozzles can proceed by way of utilisation of microelectronic fabrication techniques commonly known to those skilled in the field of semi-conductor fabrication. For a general introduction to a micro-electr mechanical system (MEMS) reference is made to standard proceedings in this field including the proceedings of the SPIE (international Society for Optical Engineering), volumes 2642 and 2882 which contain the proceedings far recent advances and conferences in this field.

In accordance with one form of construction, two wafers are utilized. Upon which the active circuitry arid inkjet print nozzles are fabricated and a further wafe~r in which the ink channels are fabricated.

Turning now to Fig. 81, there is illustrated an exploded perspective view of a single ink jet nozzle constructed in accordance with an embodiment. Construction begins which a silicon wafr 540) upon which has been fabricated and epitaxiat boron doped layer 541 and an epitaxial silicon layer 542. The boron layer is doped to a concentration of preferably I 0 20 /crn 3 of boron or more and is approximately 2 microns thick. The silicon epitaxial layer is constructed to be approximately microns thick and is doped in a manner suitable for the active semi conductor device technology.

Next, the drive transistors and distribution circuitry are constructed in accordance with the fabrication process chosen resulting in a CMOS logic and drive transistor level 543. A silicon nitride layer 544 is then deposited.

The paddle metal layers are constructed utilizing a damascene process which is a well known proces utilizing chemical mechanical polishing techniques well known for utilization as a multi-level metal application. The solenoid coils in paddle 515 (Fig, 79) can be constructed from a double layer which for a first layer 545, is produced utilizing a single damiascene process.

Next, a second layer 546 is deposited utilizing this time a dual damascene proces. The copper layers 545, W4 include contact posts 547, 548, for interconnection of the electromagnetic coil to the CMOS 543 through vias in the silicon nitride layer 544 (not shown). However, the metal post portion also includes a via interconnecting it with the lower copper level. The damascene process is finished with a planarised glass layer. The glass layers produced during utilisation of the damaiscene processes utilized for the deposition of layers 545, 546, are shown as one layer 575 in Fig. Si1.

Subsequently, the paddle is formed and separated from the adjacent glass layer by means of a plasma edge as the edge being down to the position of stop player 580. Further, the nozzle chamber 513 underneath the panel is removed by means of a silicon anisotropic wet edge which will edge down to the boron layer 541. A passivation layer is then applied. The passivation layer can comprise a conformable diamond like carbon layer or a high density SijN 4 coating, this coating provides a protective layer for the paddle and its surrounds as the paddle must exist in the highly corrosive environment water and ink.

Next, the silicon wafer can be back-edged through the boron doped layer and the ejection port 511 and an ejection port rim 550 (Fig. 79) can also be formed utilizing etching procedures, SUBSTITTE SHEET (Rule 26) (RO/AU WO 99/03680 WO 9993680PCTIAU98/00548 43 One form of alternative detaled manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the presenit embodiment can proceed utilizing the following steps; 1. Using a double sided polished wafer deposit 3 microns of epitaxial silicon heavily doped with boron.

2. Deposit 10 microns of epitaxial silicon, either p-type or n-type, depending upon the CMOS process used.

3. Complete a 0.5 micron, one poly, 2 metal CMOS process. This step is shown in Fig. 83. For clarity, these diagrams may not be to scale, and may not represet a cross section tough any single plane of the nozzle. Fig. 82 is a key to representations of various materials in these manufacturing diagram, and those of other cross referenced ink jet configurations, 4. Deposit 0. 1 microns of silicon nitride (Si3N 4 Etch the nitride layer using Mask 1. This mask defines the contacet vias from the solenoid coil to the second-level metal contacts.

6. Deposit a seed layer of copper. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistace, which increases reliability at high current densities.

7. Spin on 3 microns of resist, expose with Mask 2, and develop. This mask defines the first level coil of the solenoid. The resist acts as an electroplating mold. This step is shown in Fig. 84.

8. Electroplat 2 microns of copper.

9. Skrip the resist and etch the exposed copper seed layer. This step is shown in Fig. Deposit 0. 1 microns of silicon nitride (Si3N4).

11. Etch the nitride layer using Mask 3. This mask defines the contact vias between the first level and the second level of the solenoid.

12. Deposit a seed layer of copper.

13. Spin on 3 microns of resist, expose with Mask 4, and develop. This mask defines the second level coil of the solenoid. The resist acts as an electroplating mold. This step is shown in Fig. 86.

14. Electroplate 2 microns of copper.

Strip the resist and etch the exposed copper seed layer. This step is shown in Fig. 8 7.

17. Deposit 0.1 microns of silicon nitride.

I8. Etch the nitride and CMOS oxide layers down to silicon using Mask 5. This mask defines the nozzle chamber mask and the edges of the print heads chips for crystallographic wet etching. This step is shown in Fig. 88.

19. Crystallographically etch the exposed silicon using KOH. This etch stops on <11I1> crystallographic planes, and on the boron doped silicon buried layer. Due to the design of Mask 5, this etch undercuts the silicon, providing clearance for the paddle to rotate downwards.

20. Mount the wafer on a glas blank and back-etch the wafer using KOH, with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer. This step is shown in Fig. 89.

2 1. Plasma back-etch the boron doped silicon layer to a depth of I micros using Mask 6. This mask defines the nozzle rim. This step is shown in Fig. 22. Plasma back-etch through the boron doped layer using Mask 7. This mask defines the nozzle, and the edge of the chips. At this stage, the chips are separate, but are still mounted on the glass blank. This step is shown in SUBSTITIUTE SHEET (Rl 26) (RO/AU) WO 99/03680 PCTIAU98/00548 44 Fig. 91.

23. Strip the adhesive layer to detach the chips from the glass blank. This step is shown in Fig. 92.

24. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer.

25. Connect the print heads to their interconnect systems.

26. Hydrophobize the front surface of the print heads.

27. Fill with ink, apply a strong matgnetic field in the plane of the chip surface, and test the completed print heads, A filled nozzle is shown in Fig. 93.

Description of 1J07 F Turning to Fig. 94, there is illustrated 601 a perspective view in section of a single nozzle constructed in accordance with the techniques of an embodiment.

Each nozzle 601 includes a nozzle outlet port 602 tbr the ejection of ink from a nozzle chamber 604 as a result of activation of an electromagnetic piston 605. The electromagnetic piston 605 is activated via solenoid coil 606 which circles the piston 605. Upon a current passing through the solenoid coil 606, the piston 605 experiences a force in the direction as indicated 613 hence. As a result the piston 605 begins movement towards outlet port 602 and thereby imparts momentum to ink within the nozzle chamber 604. Torsional springs. e.g. 608, act against the moavement of piston 605, however they do not fully stop the movement of the piston.

Upon the completion of the ejection cycle, the current to the coil 606 is turned off. As a result, the torsional springs, e.g. 608, act to return the piston 605 to its rest position as initially shown in Fig. 94. Subsequently, surface tension forces cause the chamber 604 to refill with ink and to return ready for "re-tiring".

Current to the coil 606 is provided via aluminum connectors (not shown) which interconnect the coil 606 with a semni-conductor drive transistor and logic layer 618.

Construction A liquid ink jet print head 601 has one actuator device associated with each of a multitude of nozzles. It will be evident that the actuator 601 has the following major parts, which are constructed using standard semi-conductor and rnicromechanical construction techniques: Drive circuitry 618B.

2. The nozzle outlet port 602. The radius of the nozzle outlet port 602 is an important determinant of drop velocity and drop size.

3. The magnetic piston 605. This can be a cylinder of a rare earth magnetic material such as neodymium iron boron (NdFeB) or samarium cobalt (SaCo). The pistons 605 are magnetized after a last high temperature step in the fabrication of the print heads, to thereby ensure that the Curie temperature is not exceeded after magnetization. A typical print head may include many thousands of pistons all of which can be magnetized simultaneously and in the same direction.

4. The nozzle chamber 604. The nozzle chamber 604 is slightly wider than the piston 605. The gap between the piston 605 and the nozzle chamber 604 can be as small as is required to ensure that the piston does not contact the nozzle chamber during actuation or return. If the print heads are fabricated using a standard 0.5 micron lithography process, then a 1 micron gap will usually be sufficient. The nozzle chamber 604 should also be deep enough to that air ingested through the nozzle tipt 602 when the plunger returns to its quiescent state does not extend to the piston. If SUBSTTT SHEET (Rule -26) (RO/AU) WO 99103680 WO 90360P/AU98100548 it does, the ingested air bubble may form a cylindrical surface instead of a hemispherical surface. If this happens, the nozzle chamber 604 may not refill properly.

The solenoid coil 606. This is a spiral coil of copper. A double layer spiral is used to obtain a high field strength with a small device radius. Copper is used for its low resistivity, and high eleclro-migration resistance.

6. Springs 608-611. The springs 608-611 retur the piston 605 to its quiescent position after a drop 603 has been ejected. The springs can be fabricated from silicon nitride.

7. Passivation layers. All surfaces are coated with passivation layers, which may be silicon nitride (Si 3

N

4 diamond like carbon (DLC), or other chemically inert, highly impermeable layer. The passivation layers are especially important for device lifetime, as the active device is immersed in the ink.

Example method of Fabrication The print head is fabricated from two silicon wafers. A first wafer is used to fabricate the print nozzles (the print head wafer) and a second wafer is utilized to fabricate the various ink channels in addition to providing a support means for the first channel (the Ink Channel Wafer), Fig. 95 is an exploded perspective view illustrating the construction of asinigle ink jet nozzle 601 on a print head wafer. The fabrication process proceeds as follows: Start with a single silicon wafer, which has a buried epitaxial layer 621 of silicon which is heavily doped with boron. The boron should be doped to preferably 1020 atoms per cm 3 of boron or more, and be approximately 3 micron thick. A lightly doped silicon epitaxial layer 622 on top of the boron doped layer 62t should be approximately 8 micron thick, and be doped in a manner suitable for the active semiconductor device technology chosen. This is the starting point for the print head wafer. The wafer diameter should be the same as that of the ink channel wafer.

Next fabricate the drive transistors and data distribution circuitry required for each nozzle according to the process chosen, in a standard CMOS layer 618 up until oxide over the first level metal. On top of the CMOS layer 618 is deposited a silicon nitride passivation layer 625. Next, a silicon oxide layer 627 is deposited. The silicon oxide layer 627 is etched utilizing a mask for the copper coil layer. Subsequently, the copper layer 630 is deposited through the mask for the copper coil. The layers 627, 625 also include vias. for the interconnection of the copper coil layer 630 to the underlying CMOS 618 (not shown). Next, the nozzle chamber 604 (Fig. 94) is etched.

Subsequently, a sacrificial material is deposited to entirely fill the etched volume (not shown). On top of the sacrificial material a silicon nitride layer 631 is deposited, including site portions 632. Next, the magnetic material layer 633 is deposited utilizing the magnetic piston mask. This layer also includes the posts, e.g. 634.

A final silicon nitride layer 635 is then deposited onto an additional sacrificial layer (not shown) deposited to cover the bare portions of nitride layer 631 to the height of the magnetic material layer 633, utilizing a mask for the magnetic piston and the torsional springs, e.g. 608. The torsional springs, e.g. 608, and the magnetic piston 605 (see Fig. 94) are liberated by etching the aforementioned sacrificial material.

For a general introduction to a micro-electro mechanical system (MEMS) reference is made to standard proceedings in this field including the proceedings of the SPJE (International Society for Optical Engineering), volumes 2642 and 2882 which contain the proceedings for recent advances and conferences in this field.

One form of detailed manufacturing proces which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: SUBSTITUTE SHEET (Rule 26) (ItO/AU) wo 99/03680 WO 9903680PCTIAU9S/00548 46 1. Using a double sided polished wafer deposit 3 microns of epitaxial silicon heavily doped with boron.

3. Complete a 0.5 micron, one poly, 2 metal CMOS process. The metal layers are copper instead of aluminum, due to high current densities and subsequent high temperature processing. This step is shown in Fig. 97.

For clarity, these diagrams may not be to scale, and may not represent a cross section though any single plane of the nozzle. Fig. 96 is a key to representations of various materials in these manutheturing diagrams, and those of other cross referenced ink jet configurations.

4. Deposit 0.5 microns of low stress PECVD silicon nitride (5i 3

N

4 The nitride acts as a dielectric, and etch stop, a copper diffusion barrier, and an ion diffusion barrier. As the speed of operation of the print head is low, the high dielectric constant of silicon nitride is not important, so the nitride layer can be thick compared to sub-micron CMOS back-end processes.

Etch the nitride layer using Mask 1. This mask defines the contact vias from the solenoid coil to the second-level metal contacts, as well as the nozzle chamber. This step is shown in Fig. 98.

6. Deposit 4 microns of PECVD glass.

7. Etch the glass down to nitride or second level metal using Mask 2. This mask defines the solenoid. This step is shown in Fig. 99.

8. Deposit a thin banier layer of Ta or TaN, 9. Deposit a seed layer of copper. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistance, which increases reliability at high current densities.

10. Electroplae 4microns of copper.

11. Planarize using CMP. Steps 4 to I11 represent a copper dual damascene process, with a 4:1 copper aspect ratio (4 microns high, 1 micron wide). This step is shown in Fig. 100.

12. Etch down to silicon using Mask 3. This mask defines the nozzle cavity. This step is shown in Fig. 101.

13. Crystallograhically etch the exposed silicon using KOH. This etch stops on <Ill crystallographic planes, and on the boron doped silicon buried layer. This step is shown in Fig. 102.

14. Deposit 0.5 microns of low stress PECVD silicon nitride.

Open the bond pads using Mask 4.

17. Deposit a tick sacrificial layer low stres glass), filling the nozzle cavity. Planarize the sacrificial layer to a depth of 5 microns over the nitride surface. This step is shown in Fig. 103.

18. Etch the sacrificial layer to a depth of 6 microns using MaskS5. This mask defines the permanent magnet plus the magnet support posts. This step is shown in Fig. 104.

19. Deposit 6 microns of permanent magnet material such as neodymium iron boron (NdFeB). Planarize.

This step is shown in Fig. 105.

Deposit 0.5 microns of low stress PECVD silicon nitride.

2 1. Etch the nitride using Mask 6, which defines the spring. This step is shown in Fig. 106.

22. Anneal the permanent magnet material at a temperature which is dependant upon the material 23. Place the wafer is a uniformn magnetic field of 2 Tesla (20.000 Gauss) with the field normal to the chip surface. This magnetizes the permanent magnet.

SUBSTITUTE SHEET (Rate 26) (lR)/AU) WO "/03680 WO 993680P/AU98o054s 47 24. Mount the wafer ont a glass blank and bck-etch the wafer using KOH, with no mask. This etch thins the wafer and stops at the buried heron doped silicon layer. This step is shown in Fig. 107.

Plasma back-etch the boron doped silicon layer to a depth oftI micron using Mask 7. This mask defines the nozzle rim. This step is shown in Fig. 108.

26. Plasma back-etch through the boron doped layer using Mask 8. This mask defines the nozzle, and the edge of the chips.

27. Plasma back-etch nitride up to the glass sacrificial layer through the holes in the boron doped silicon layer. At this stage, the chips are separate, but are still mounted on the glass blank. This step is shown in Fig. 109.

28. Strip the adhesive layer to detach the chips from the glass blank.

29. Etch the sacrificial glass layer in buffered HF. This step is shown in Fig. 110.

Mount the print heads in their packaging, which may he a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer.

3 1. Connect the print heads to their interconnect systems.

32. Hydrophobize the front surface of the print heads.

33. Fill the completed print heads with ink and test them. A filled nozzle is shown in Fig. Ill1.

Descriptio oIJOS SF In an embodiment, a shutter is actuated by means of a magnetic coil, the coil being utilized to move an attached shutter to thereby cause the shutter to open or close. The shutter is disposed between an ink reservoir having an oscillating ink pressure and a nozzle chamnber having an ink ejection port defined therein for the ejection of ink.

When the shutter is open ink is allowed to flow from the ink reservoir through to the nozzle chamber and thereby caus an ejection of ink from the ink ejection port. When the shutter is closed, the nozzle chamber remains in a stable state such that no ink is ejected from the chamber.

Turning now to Fig. 112, there is illustrated a single ink jet nozzle arrangement 7 10 in a closed position.

The arrangement 710 includes a series of shutters 711 which are located above corresponding apertures to a nozzle chamber. In Fig. 113, the ink jet nozzle 710 is illustrated in an open position which also illustrates the apertures 712 providing a fluid interconnection to a nozzle chamber 713 and an ink ejection port 714. The shutters e.g. 711 are intcernected together and futher connected to an arm 716 which is pivotally mounted about a pivot point 717 about which the shutters e.g. 711 rotae. The shutter 711 and arm 716 are constructed from nickel iron (NiFe) so as to be magnetically attracted to an electromagnetic device 719. The electromagnetic device 719 comprises a NiFe core 720 around which is constructed a copper coil 721. The copper coil 721 is connected to a lower drive layer via vias 723,724. The coil 719 is activated by sending a current through the coil 721 which results in its magnification and corresponding attraction in the areas 726,727. The high levels of attraction are due to its close proximity to the ends of the electromagnet 719. This results in a general rotation of the surfaces 726,727 around the pivot point 717 which in turn results in a corresponding rotation of the shutter from a closed to an open position.

A number of coiled springs 730-732 are also provided. The coiled springs store energy as a consequence of the rotation of the shutter 711. Hence, upon deactivation of the electromagnet 719 the coil springs 730-732 act to return the shutter to its closed position. As mentioned previously, the opening and closing of the shutter 711 allows for the flow of ink to the ink nozzle chamber for a subsequent ejection. The coil 719 is SUBSTrnJT SHEET (Rule 26) (110/AU) WO 99/03690 WO 9903680PCT/AU9S/00548 48 activated rotating the arm 716 bringing the surfaces 726,727 into close contact with the electromagnet 719. The surfaces 726,727 are kept in contac with the electromagnet 719 by means of utilisation of a keeper current which, due the close proximity between the surfaces is substantially less than that required to initially move the arm 716.

The shutter 711 is maintained in the plane by means of a guide 734 which overlaps slightly with an end portion of the shutter 711.

Turning now to Fig. 114, there is illustrated an exploded perspective of one form of construction of a nozzle arrangement 710 in accordance with an embodiment The bottom level consists of a boron doped silicon layer 740 which can be formed from constructing a buried epitaxial layer within a selected wafer and then back etching utilising the boron doped layer as an etch stop. Subsequently, there is provided a silicon layer 741 which includes a crystal lographically etched pit forming the nozzle chamber 713. On top of the silicon layer 741 there is constructed a 2 micron silicon dioxide layer 742 which includes the nozzle chamber pit opening whose side walls are passivated by a subsequent nitride layer. On top of the silicon dioxide layer 742 is constructed a nitride layer 744 which provides passivation of the lower silicon dioxide layer and also provides a base on which to construct the electromagnetic portions and the shutter. The nitride layer 744 and lower silicon dioxide layer having suitable is vies for the interconnection to the ends of the electromagnetic circuit for the purposes of supplying power on demand to the electromagnetic circuit.

Next, a copper layer 745 is provided. The copper layer providing a base wiring layer for the electromagnetic array in addition to a lower portion of the pivot 717 and a lower portion of the copper layer being utilised to form a part of the construction of the guide 734.

Next, a NiFe layer 747 is provided which is utilized for the formation of the internal portions 720 of the electromagnet, in addition to the pivot, aperture arm and shutter 711 in addition to a portion of the guide 734, in addition to the various spiral springs. On top of the NiFc layer 747 is provided a copper layer 749 for providing the top and side windings of the coil 721 in addition to providing the formation of the top portion of guide 734. Each of the layers 745,747 can be conductively insulated from its surroundings where required through the utilisation of a nitride passivation layer (not shown). Further, a top passivation layer can be provided to cover the various top layers which will be exposed to the ink within the ink reservoir and nozzle chamber. The various levels 745,749 can be formed through the utilisation of supporting sacrificial structures which are subsequently sacrificially etched away to leave the operable device.

One form of detailed manufacturing proces which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer deposit)3 microns of epitaxial silicon heavily doped with boron.

2. Deposit 10 microns of epitaxial silicon, either p-type or n-type depending upon the CMOS process used.

3. Complete a 0.5 micron, one poly, 2 metal CMOS process. This step is shown in Fig. 116. For clarity, these diagrams may not be to scale, and may not represent a cross section though any single plane of the nozzle. Fig.

115 is a key to representations of various materials in these manufacturing diagrams, and those of other cross referenced ink jet configurations.

4. Etch the CMOS oxide layers down to silicon or aluminum using Mask 1. This mask defines the nozzle chamber, and the edges of the print heads chips. This step is shown in Fig. 117.

SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99103680 WO 993680P/AU9/0548 49 Crystallographically etch the exposed silicon using KOK. This etch stops on <1Il> ctystallographic planes, and on the boron doped silicon buried layer. This step is shown in Fig. 11l8.

6. Deposit 10 microns of sacrificial material. Planmaize down to oxide using CMI'. The sacrificial material temporarily fills the nozzle cavity. This step is shown in Fig. 119.

7. Deposit 0.5 microns of silicon nitride (Si 3

N

4 8. Etch nitride and oxide down to aluminum or sacrificial material using Mask 3. This mask defines the contact: vias from the aluminum electrodes to the solenoid, as well as the fixed grill over the nozzle cavity. This step is shown in Fig. 120.

9. Deposit a seed layer of copper. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistaince, which increases reliability at high current densities, Spin on 2 microns of resist, expose with Mask 4, and develop. This mask defines the lower side of the solenoid square helix, as well as the lowest layer of the shutter grill vertical stop. The resist acts as an electroplating mold. This step is shown in Fig. 121.

11. Electroplate 1 micron of copper. This step is shown in Fig. 122.

12. Strip the resist and etch the exposed copper seed layer. This step is shown in Fig. 123.

13. Deposit 0. 1 microns of silicon nitride.

14. Deposit 0.5 microns of sacrificial material.

Etch the sacrificial material down to nitride using Mask 5. This mask defines the solenoid, the fixed magnetic pole, the pivot, the spring posts, and the middle layer of the shutter grill vertical stop. This step is shown in Fig. 124.

16. Deposit a seed layer of cobalt nickel iron alloy. CoNiFe is chosen due to a high saturation flux density of 2 Tesla, and a low coercivity. [Osaka, Tetsuya et al, A soft magnetic CoNiFe film with high saturation magnetic flux density, Nature 392, 796-798 (1998)].

17. Spin on 3 microns of resist, expose with Mask 6, and develop. This mask defines all of the soft magnetic parts, being the fixed magnetic pole, the pivot, the shutter grill, the lever arm, the spring posts, and the middle layer of the shutter grill vertical stop. The resist acts as an electroplating mold. This step is shown in Fig. 125.

18. Electroplate 2 microns of CoNiFe. This step is shown in Fig. 126.

19. Strip the resist and etch the exposed seed layer. This step is shown in Fig. 127.

Deposit 0. 1 microns of silicon nitride (Si 3 N4).

21. Spin on 2 microns of resist expose with Mask 7, and develop. This mask defines the solenoid vertical wire segments, fbr which the resist acts as an electroplating mold. This step is shown in Fig. 128.

22. Etch the nitride down to copper using the Mask 7 resist.

23. Electroplate 2 microns of copper. This step is shown in Fig. 129.

24. Deposit a seed layer of copper.

25. Spin on 2 microns of resist, expose with Mask 8, and develop. This mask defines the upper side of the solenoid square helix, as well as the upper layer of the shutter grill vertical stop. The resist acts as an electroplating mold. This step is shown in Fig. 130.

26. Electroplate 1 micron of copper. This step is shown in Fig. 13 1.

27. Strip the resist and etch the exposed copper seed layer, and tip the newly exposed resist. This step is shown in Fig. 132.

SUBS Irr Um SHEET (Rule 26) (RO/AU) WO 99/03680 WO 9903680PCTAU91YOOS4S 28. Deposit 0. 1 microns of conformal silicon nitride as a concision barrier.

29. Open the bond pads using Mask 9.

Wafer probe. All electrical connections are compete at this point, bond pad are accessible, and the chips are not yet separated.

3 1. Mount the wafer an a gls blank and back-etch the wafer using KOH, with no mask- This etch thins the wafer and stops at the buried boron doped silicon layer. This step is shown in Fig. 133.

32. Plasma back-etch the boron doped silicon layer to a depth oftI micron using Mask 9. This mask defines the nozzle rim. This step is shown in Fig. 134.

33. Plasma back-etch through the baron doped layer using Mask 10. This mask defines the nozzle, and the edge of the chips. At this stage, the chips are separate, but are still mounted on the glass blank. This step is shown in Fig. 135.

34. Detach the chips from the glass blank. Strip all adhesive, resist, sacrificial, and exposed seed Layers. This step is shown in Fig. 136.

Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer. The package also includes a piezoelectric actuator attached to the rear of the ink channels. The piezoelectric actuator provides the oscillating ink pressure required for the ink jet operation.

36. Connect the print heads to their interconnect systems.

37. Hydrophobize the front surface of the print heads.

38. Fill the completed print heads with ink and test them. A filled nozzle is shown in Fig. 137.

Desrition of IJO TF In an embodiment, an array of ink jet nozzles is provided with each of the nozzles being under the influence of a outside pulsed magnetic field. The outside pulsed magnetic field causes selected nozzles to eject ink from their ink nozzle chambers.

Turning to Fig. 138 and Fig. 139, there is illustrated a side perspective view, partly in section, of a single ink jet nozzle 9 1. Fig. 138 illustrates a nozzle in a quiescent position and Fig. 139 illusnrates a nozzle in an ink ejection position. The ink jet nozzle 910 has an ink ejection port 911 tbr the ejection of ink on demand. The ink jet ejection port 911 is connected to an ink nozzle chamber 912 which is usually filled with ink and supplied from an ink reservoir 913 via holes eg. 915.

A magnetic actuation device 925 is included and comprises a magnetic soft core 917 which is surrounded by a nitride coaxing eg. 918S. The nitride coating includes an end protuberance 927.

The magnetic core 917, operates under the influence of an external pulsed magnetic field. Hence, when the external magnetic field is very high, the actuator 925 is caused to move rapidly downwards and to thereby cause the ejection of ink from the ink ejection port 911. Adjacent the actuator 92-0 is provided a locking mechanism 920 which comprises a thermal actuator which includes a copper resistive circuit having two arms 922, 924. A current is passed through the connected arms 922, 924 thereby causing them to be heated. The arm 922, being of a thinner construction undergoes more resistive heating than the arm 924 which has a much thicker structure. The arm 922 is also of a serpentine nature and is encased in polytetfluoroethylene (PTFE) which has a high coefficient of thermal expansion, thereby increasing the degree of expansion upon heating, The copper portions expand with the PTFE SUBSTITUTE SHEET (Rule 26) (RO/AU) wo "/03680 WO 993680P/AU98/00548 51 portions by means of concertinaing. The arm 924 has a thinned portion 929 (Fig. 140) which becomes the concentrated bending region in the resolution of the various force activated upon heating. Hence, any bending of arm 924 is accentuated in the region 929 and upon heating, the region 929 bends so that end portion 926 (Fig. 138) moves out to block any downward movement of the edge 927 of the actuator 925. Hence, when it is desired to eject an ink drop from a current nozzle chamber, the locking mechanism 920 is not activated and as a result ink is ejected from the ink ejection port during the next external magnetic pulse phase. When a current nozzle is not to eject ink, the locking mechanism 920 is activated to block any movement of the actuator 925 and therefore stop the ejection of ink from the chamber.

Importantly, the actuator 920 is located within a cavity 928 such that the volume of ink flowing past arm 922 is extremely low whereas the arm 924 receives a much larger volume of ink flow during operation.

Turning now to Fig. 140, there is illustrated an exploded perspective view of a single ink jet nozzle 9 illustrating the various layers which make up the nozzle. The nozzle 910 can be constructed on a semiconductor wafer utilizing standard semiconductor processing techniques in addition to those techniques commonly used for the construction of micro-electromechanical systems (MEMS). For a general introduction to a micro-electro mechanical system (MEMS) reference is made to standard proceedings in this field including the proceedings of the SPIE (International Society for Optical Engineering), volumes 2642 and 2882 which contain the proceedings for recent advances and conferences in this field. At the bottom level 930 is constructed the nozzle plate including the ink ejection port 911. The nozzle plate 930 can be constructed from a buried boron doped epitaxia] Layer of a silicon wafer which has been back etched to the point of the epitaxial layer. The epitaxial layer itself is then etched utilizing a mask soas toform the nozrle rimn(not shown) and the nozze hole 911.

Next, is the silicon wafer layer 932 which is etched so as to include the nozzle chamber 912. The silicon layer 932 can be etched to contain substantially vertical side walls through the utilization of high density, low pressure plasma etching such as that available from Surface Technology Systems and subsequently filled with sacrificial material which will be later etched away.

On top of the silicon layer is deposited a two level CMOS circuitry layer 933 which comprises substantially glass in addition to the usual metal and poly layers. The layer 933 includes the formation of the heater element contacts which can be constructed from copper. The PTFE layer 935 can be provided as a departure f-rm normal construction with a bottom PTFE layer being first deposited fbllowed by the copper layer 934 and a second PTFE layer to cover the copper layer 934.

Next, a nitride passivation layer 936 is provided which acts so provide a passivation surface for the lower layers in addition to providing a base for a soft magnetic Nickel Ferrous layer 917 which fbrms the magnetic actuator portion of the actuator 92-5. The nitride layer 936 includes bending portions 940 utilized in the bending of the actuator.

Next a nitride passivation layer 939 is provided so as to passivate the top and side surfaces of the nickel iron (NiFe) layer 917.

One form of derailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer deposit 3 rnicrons of eptaxia silicon heavily doped with boron.

SUBSTITUTE SHEET (Rule 26) (RCWAU) WO 99103680 PCT/AU98/0048 52 2. Deposit 10 microns of epitaxial silicon, either p-type or n-type, depending upon the CMOS process used.

3. Complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process. Relevant features of the wafer at this step are shown in Fig. 142. For clarity, these diagrams may not be to scale, and may not represent a cross section though any single plane of the nozzle. Fig. 141 is a key to representations of various materials in these manufacturing diagrams, and those of other cross referenced ink jet configurations.

4. Etch the CMOS oxide layers down to silicon or aluminum using Mask I. This mask defines the nozzle chamber, and the edges of the print head chips. This step is shown in Fig. 143.

Crystallographically etch the exposed silicon using, for example, KOH or EDP (ethylenediamine pyrocatechol). This etch stops on <11 crystallographic planes, and on the boron doped silicon buried layer. This step is shown in Fig. 144.

6. Deposit 0.5 microns of silicon nitride (Si 3

N

4 7. Deposit 10 microns of sacrificial material. Planarize down to one micron over nitride using CMP. The sacrificial material temporarily fills the nozzle cavity. This step is shown in Fig. 145.

8. Deposit 0.5 microns ofpolytetrafluoroethylene

(PTFE).

9. Etch contact vias in the PTFE, the sacrificial material, nitride, and CMOS oxide layers down to second level metal using Mask 2. This step is shown in Fig. 146.

Deposit micron of titanium nitride (TiN).

11. Etch the TN using Mask 3. This mask defines the heater pattern for the hot arm of the catch actuator, the cold arm of the catch actuator, and the catch. This step is shown in Fig. 147.

12. Deposit 1 micron of PTFE.

13. Etch both layers of PTFE using Mask 4. This mask defines the sleeve of the hot arm of the catch actuator. This step is shown in Fig. 148.

14. Deposit a seed layer for electroplating.

I5. Spin on 11 microns of resist, and expose and develop the resist using Mask 5. This mask defines the magnetic paddle. This step is shown in Fig. 149.

16. Electroplate 10 microns of ferromagnetic material such as nickel iron (NiFe). This step is shown in Fig.

150.

17. Strip the resist and etch the seed layer.

18. Deposit 0.5 microns of low stress PECVD silicon nitride.

19. Etch the nitride using Mask 6, which defines the spring. This step is shown in Fig. 15 1.

Mount the wafer on a glass blank and back-etch the wafer using KOH with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer. This step is shown in Fig. 152.

21. Plasma back-etch the boron doped silicon layer to a depth of 1 micron using Mask 7. This mask defines the nozzle rim. This step is shown in Fig. 153.

22. Plasma back-etch through the boron doped layer using Mask 8. This mask defines the nozzle, and the edge of the chips.

23. Plasma back-etch nitride up to the glass sacrificial layer through the holes in the boron doped silicon layer. At this stage, the chips are separate, but are still mounted on the glass blank. This step is shown in Fig. 154.

SUBSTITUTE SHEET (Rule 26) (ROIAU) WO 99103680 WO 9903680PCT/AU9S/00!548 53 24. Strip the adhesive layer to detach the chips from the gls blank.

Etch the sacrificial layer. This step is shown in Fig. 155.

26. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply difbrent colors of ink to the appropriate regions of the front surfhce of the wafer.

27. Connect toe print heads to their interconnect systems.

28. Kydrophobize the front surface of the print heads.

29. Pill the completed print heads with ink, apply an oscillating magnetic field, and test the print heads. This step is shown in Fig. 156.

Description of UlII F In an embodiment there is provided an ink jet nozzle and chamber filled with ink. Within said jet nozzle chamber is located a static coil and a moveable coil. When energized the static and movable coils are attracted towards one another, loading a spring. The ink drop is ejected from the nozzle when the coils are dc-energized. Turn now to Fig, 157 to Fig. 160, there is illustrated schematically the operation of an embodiment In Fig. 157, there is shown a single ink jet nozzle chamber 1010 having an ink ejection port loll and ink meniscus in this position 10 12.

Inside the nozzle chamber 1010 are located a fixed or static coil 1014 and a moveable coil 1015. The arrangement of Fig. 157 illustrates the quiescent stare intoe ink jet nozzle chamber.

The two coils are then energised resulting in an attraction to one another, This results in the movable plate 10 15 moving towards the static or fixed plate 1014 as illustrated in Fig. 158. As a result of the movement.

springs 10 18,1019 are loaded. Additionally, the movement of coil 10 15 may cause ink to flow out of the chamber 10 10 in addition to a change in the shape of the meniscus 10 12. The coils are energised for long enough for the moving coil 1015 to reach its position (approximate two microseconds). The coil currents are then turned to a lower "level" while the nozzle fills. The keeper power can be substantially less than the maximum current level utilised to move the plate 10 15 because the magnetic gap between the plates 10 14 and 10 15 is at a minimum when the moving coil 10 15 is at ins stop position. The surface tension on the meniscus 10 12 inserts a net force on the ink which results in nozzle refilling as illustrated in Fig. 159. The nozzle refilling replaces the volume of the piston withdrawal with ink in a process which should take approximately 100 microseconds.

Turning to Fig. 160, the coil current is then turned offeand the moveable coil 1015 acts as a plunger which is accelerated to its normal position by the springs 1018, 1019 as illustrated in Fig. 160. The spring force on the plunger coil 1015 will be greatest at the beginning of its stroke and slows as the spring elastic stress falls to zero. As a result. the acceleration of plunger plate 10 15 is high at the beginning of the stroke but decreases during the stroke resulting in a more uniform ink velocity during the stroke. The movement plate 1015 causes the meniscus to bulge and break off performing ink drop 1020. The plunger coil 1015 in turn settles in its quiescent position until the next drop ejection cycle.

Turning now to Fig. 161, there is illustrated a perspective view of one form of construction of an ink jet nozzle 10 10. The ink jet nozzle 10 10 can be constructed on a silicon wafer base 1022 as pant of a large array of nozzles 1010 which can be formed for the purposes of providing a print head having a certain dpi, for example, a 1600 dpi print head. The print head 1010 can be constrructed utilizing advanced silicon semi-conductor fabrication and micro machining and micro fabrication proces technology. The wafer is first processed to include lower level drive circuitry (not shown) befbre being finished off with a two microns thick dioxide layer 1022 with appropriate SUBSTifUT SHEET (Rule 26) (110/AU) WO "103690 WO 9903680PCT/AU98M0548 54 vias for interconnection. Preferably, the CMOS layer can include one level of metal for providing basic interconnects. On top of the glass layer 1022 is constructed a nitride layer 1023 in which is embedded two coil layers 1025 and 1026. The coil layers 1025, 1026 can be embedded within the nitride layer 1023 througSh the utilisation of the well-known dual damnascene process and chemical mechanical planarization techniques ('Chemical Mechanical Planarisation of Micro Electronic Materials' by Starger Wald et al published 1997 by John Wiley and Sons Inc., New York, New York). T'he two coils 1025,1026 are interconnected utilizing a fire at their central point and are further connected, by appropriate vias at ends 1028,1029 to the end points 1028,1029. Similarly, the moveable coil can be formed from two copper coils 1031,1032 which are encased within a further nitride layer 1033. The copper coil 1031,1032 and nitride layer 1033 also include torsional springs 1036-1039 which are formed so that the top moveable coil has a stable state away from the bottom fixed coil. Upon passing a current through the various copper coils, the top copper coils 1031,1032 are attracted to the bottom copper coils 1025,1026 thereby resulting in a loading being placed on the torsional springs 1036-1039 such thA when the current is turned off, the springs 1036-1039 act to move the top moveable coil to its original position. The nozzle chamber cart be forned via nitride wall portions e.g.

1040,1041 having slots between adjacent wall portions. The slots allow for the flow of ink into the chamber as required. A top nitride plate 1044 is provided to cap the top of the internals of 1010 and to provide in flow channel support. The nozzle plate 1044 includes a series of holes 1045 provided to assist in sacrificial etching of lower level layers. Also provided is the ink injection nozzle 1011 having a ridge around its side so as to assist in resisting any in flow on to the outside surface of the nozzle 1010. The etched through holes 1045 are of much smaller diameter than the nozzle hole 10 11 and, as such, surface tension will act to retain the ink within the through holes of 1045 whilst simultaneously the injection of ink from nozzle 1011.

As mentioned previously, the various layers of the nozzle 1010 can be constrcted in accordance with standard semni-conductor and micro mechanical techniques. These techniques utilize the dual damnascene process as mentioned earlier in addition to the utilisation of sacrificial etch layers to provide support for structures which are later released by means of etching the sacrificial layer.

The ink can be supplied within the nozzle 10 10 by standard techniques such as providing ink channels along the side of the wafer so as to allow the flow of ink into the area under the surface of nozzle plate 1044. Alternatively, ink channel portals can be provided through the wafer via means of utilisation of a high density low pressure plasma etch processing system such as that available from surface technology system and known as their Advanced Silicon Edge (ASE) process. The etched portals 1045 being so small that surface tension affects not allow the ink to leak out of the small portal holes. In Fig. 162, there is shown a final assembled ink jet nozzle ready for the ejection of ink.

One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer, Complete drive transistors data distribution, and tinming circuits using a 0.5 micron, one poly, 2 metal CMOS process. This step is shown in Fig. 164. For clarity, these diagr-ams may not be to scale, and may not represent a cross section though any single plane of the nozzle. Fig. 163 is a key to representations of various materials in these manufacturing diarams, and those of other cross referenced ink jet configurations.

2. Deposit 0.5 microns of low stres PECVD silicon nitride (Si3N 4 The nitride acts as a dielectric, and etch -stop, a copper diffusion barrier, and an ion diffusion barrier. As the speed of operation of the print head is low, the SUBSTITUT SHEE (Rule 26) (.OIAUT) WO 99/03680 PCTIAU98/00548 high dielectric constant of silicon nitride is not important, so the nitride layer can be thick compared to sub-micron CMOS back-end processes.

3. Etch the nitride layer using Mask 1. This mask defines the contact vias from the solenoid coil to the second-level metal contacts. This step is shown in Fig. 165.

4. Deposit I micron of PECVD glass.

Etch the glass down to nitride or second level metal using Mask 2. This mask defines first layer of the fixed solenoid. This step is shown in Fig. 166.

6. Deposit a thin barrier layer of Ta or TaN.

7. Deposit a seed layer of copper. Copper is used for its low resistivity (which results in higher efficiency) and its high eiectromigration resistance, which increases reliability at high curret densities.

8. Electroplate 1 micron of copper.

9. Planarize using CMP. Steps 2 to 9 represent a copper dual damascene process. This step is shown in Fig.

167.

I0. Deposit 0.5 microns of low stress PECVD silicon nitride.

11. Etch the nitride layer using Mask 3. This mask defines the defines the vias from the second layer to the first layer of the fixed solenoid. This step is shown in Fig. 168.

12. Deposit 1 micron of PECVD glass.

13. Etch the glass down to nitride or copper using Mask 4. This mask defines second layer of the fixed solenoid. This step is shown in Fig. 169.

14. Deposit a thin barrier layer and seed layer.

Electroplate 1 micron of copper.

16. Planarize using CMP. Steps 10 to 16 represent a second copper dual damascene process. This step is shown in Fig. 170.

17. Deposit 0.5 microns of low stress PECVD silicon nitride.

18. Deposit 0.1 microns of PTFE. This is to hydrophobize the space between the two solenoids, so that when the nozzle fills with ink, this space forms an air bubble. The allows the upper solenoid to move more freely.

19. Deposit 4 microns of sacrificial material. This forms the space between the two solenoids.

Deposit 0.1 microns of low stress PECVD silicon nitride.

21. Etch the nitride layer, the sacrificial layer, the PTFE layer, and the nitride layer of step 17 using Mask This mask defines the vias from the first layer of the moving solenoid to the second layer the fixed solenoid. This step is shown in Fig. 171.

22. Deposit I micron of PECVD glass.

23. Etch the glass down to nitride or copper using Mask 6. This mask defines first layer of the moving solenoid. This step is shown in Fig. 172.

24. Deposit a thin barrier layer and seed layer.

Electroplate 1 micron of copper.

26. Planarize using CMP. Steps 20 to 26 reprcsent a third copper dual damascene process. This step is shown in Fig. 173.

27. Deposit 0.1 microns of low stress PECVD silicon nitride.

SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 9,51/03680 PCTIAU98/00548 56 28. Etch the nitride layer using Mask 7. This mask defines the vias from the second layer the moving solenoid to the first layer of the moving solenoid. This step is shown in Fig. 174, 29. Deposit 1 micron of PECVD glass.

Etch the glass down to nitride or copper using Mask 8. This mask defines second layer of the moving solenoid. This step is shown in Fig. 175.

3 1. Deposit a thin barrier layer and seed layer.

32. Electrplate 1 micron of copper.

33. Planarize using CMP. Steps 27 to 33 represent a fourth copper dual damascene process. This step is shown in Fig. 176.

34. Deposit 0. 1 microns of low stress PECYD silicon nitride.

Etch the nitride using Mask 9. This mask defines the moving solenoid, including its springs, and al lows the sacrificial material in the space between the solenoids to be etched. It also defines the bond pads. This step is shown in fig. 177.

36. Wafer probe. All electrical connections are complete at this point bond pads are accessible, and the chips are not yet separated.

3 7. Deposit 10 microns of sacrificial material 38. Etch the sacrificial material using Mask 10. This mask defines the nozzle chamber wall. This step is shown in Fig. 178.

39. Deposit 3 microns of PECVD glass.

40. Etch to a depth of I micron using Mask 11. This mask defines the nozzle rim. This step is shown in Fig.

179.

41. Etch down to the sacrificial layer using Mask 12. This mask defines the roof of the nozzle chamber, and the nozzle itself. This step is shown in Fig. 180.

42. Back-etch completely through the silicon wafer (with, for example, an ASE Advanced Silicon Etcher from Surfac Technology Systems) using Mask 7. This mask defines the ink inlets which are etched through the wafer. The wafer is also diced by this etch. This step is shown in Fig. 18 1.

43. Etch the sacrificial material. The nozzle chambers are cleared, the actuators freed, and the chips are separated by this etch This step is shown in Fig. 132.

4.Mount the print heads in their packaging, which may be a molded plastic fanner incorporating ink channels which supply the appropriate color ink to the ink inlets at the back of the wafer.

Connect the print heads to their interconnect systems. For a low profile connection with minimum disruption of airflow, TAB may be used, Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper.

46. Hydrophobize the front surface of the print heads.

47. Fill the completed print heads with ink and test them. A filled nozzle is shown in Fig. 183.

Dection ofU12 F in an embodimnt, a linear stepper motor is utilized to control a plunger device. The plunger device compressing ink within a nozzle chamber so as to thereby cause the ejection of ink from the chamber on demand.

SUBSTrrUT SHEET (Rule 26) (RO/AU) WO 99/03680 WO 9/160PIA09/00548 57 Turning to Fig. 184, there is illustrated a single nozzle arranlgemet 111 0 as constructed in accordance with an embodiment. The nozzle arrangement 11I10 includes a nozzle chamber I1I1I1 into which ink flows via a nozzle chamber filter portion 1114 which includes a series of posts which filter out foreign bodies in the ink in flow. The nozzle chamber I1I1I1 includes an ink ejection port 1115 for the ejection of ink on demand. Normally, the nozzle chamber IllI is filled wihhink.

A linear actuator 1116 is provided for rapidly compressing a nickel ferrous plunger 11I18 into the nozzle chamber I111I1 sona to compress the volume of ink within chamber 111110 t thereby cause ejection of drops from the ink ejection port 1115. The plunger 1118 is connected to the stepper moving polo device 1116 which is actuated by means of a three phase arrangement of electromagnets 1120 to 113 1. The electromagnets are driven i n three phases with electro magnets 1120, 1126, 11t23 and 1129 being drivens in a first phase, electromagnets 1121, 1127, 1124, 1130 being driven in a second phase and electromagnets 1122, 1128, 1125, 1131 being driven in a third phase. The electromagnets are driven in a reversible manrif so as to do-actuate plunger 1118 via actuator 1116. The actuator 1116 is guided at one end by a means of guide 1133, 1134. At the other end, the plunger 1118 is coated with a hydrophobic material such as polytetrafluoroethylene (MTE) which can fbrm a major part of the plunger 1118. The PTFE acts to repel the ink from the nozzle chamber I1I11 resulting in the creation of a membrane eg. 1]138, 1139 between the plunger 11I18 and side wails eg. 1136, 1137. The surface tension characteristics of the membranes 113 8, 1139 act to balanced one another thereby guiding the plunger 11I18 within the nozzle chamber. The mueniscus eg.

213 8, 1139 further stops ink from flowing out of the chamber 1111I and hence the electromagnets 1120 to 113 1 can be operated in normal air.

The nozzle arrangement 11I10 is therefore operated to eject drops on demand by means of activating the actuator 1116 by appropriately synchronized driving of electromagnets 1120 to 113 1. The actuation of the actuator 1116 results in the plunger 1118 moving towards the nozzle ink ejection port 1115 thereby causing ink to be ejected from the port 1115. 1 Subsequently, the electromagnets are driven in reverse thereby moving the plunger in an opposite direction resulting in the in flow of ink from an ink supply connected to the ink inlet port 1114.

Preferably, multiple ink nozzle arrangements 1 110 can be constructed adjacent to one another to form a multiple nozzle ink ejection mechanism. The nozzle arrangements 11I10 are preferably constructed in an array print head constructed on a single silicon wafer which is subsequently diced in accordance with requirements. The diced print heads can then be interconnected to an ink supply which can comprise a through chip ink flow or ink flow from the side of achip.

Turning now to Fig. 185, there is shown an exploded perspective of the various layers of the nozzle arrangement 11I10. The nozzle arrangement can be constructed on top of a silicon wafer 1140 which has a standard electronic circuitry layer such as a two level metal CMOS layer 114 1. The two metal CMOS provides the drive and control circuitry for the ejection of ink from the nozzles by interconnection of the electromagnets to the CMOS layer.

On top of the CMOS layer 1141 is a nitride passivation layer 1142 which passivates the lower layers against any ink erosion in addition to any etching of the lower CMOS glass layer should a sacrificial etching process be utilized in the construction of the nozzle arrangement 11I10.

On top of the nitride layer 1142 is constructed various other layers. The wafer layer 1140, the CMOS layer 1141 and the nitride passivation layer 1142 are constructed with the appropriate fires for interconnecting to the above layers. On top of the nitride layer 1142 is constructed a bottom copper layer 1143 which interconnects with the SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PaIAU9/00548 58 CMOS layer 1141 as appropriate. Next, a nickel ferrous laye 1145 is constructed which includes portions for the core of the electromagnets and the actuator 1116 and guides 1131, 1132. On top of the NiFe layer 1145 is onstructed a second copper layer 1146 which forms the rest of the electromagnetic device. The copper layer 1146 can be constructed utilizing a dual damascene process. Next a PTE layer 1147 is laid down followed by a nitride layer 1148 which includes the side filter portions and side wall portions of the nozzle chamber In the top of the nitride layer 1148, the ejection port 11 15 and the rim 1151 are constructed by means of etching. In the top of the nitride layer 1148 is also provided a number of apertures 1150 which are provided lbr the sacrificial etching of any sacrificial material utilized in the construction of the various lower layers including the nitride layer 1148.

It will be understood by those skilled in the art of construction of micro-electro-mechankcal systems (MEMS) that the various layers 1143, 1145 to 1148 can be constructed by means of utilizing a sacrificial material to deposit the structure of various layers and subsequent etching away of the sacrificial material as to release the structure of the nozzle arrangement 11I10.

For a general introduction to a micro-electro mechanical system (MEMS) reterence is made to standard proceedings in this field including the proceedings of the SPIE (International Society for Optical Engineering), volumes 2642 and 2882 which contain the proceedings for recent advances and conferences in this field.

One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print beads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer, Complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process. This step is shown in Fig. 187. For clarity, these diagrams may not be to scale, and may not represent a cross section though any single plane of the nozzle. Fig. 186 is a key to representations of various materials in these manufacturing diagramns, and those of other cross referenced ink jet configurations.

2. Deposit 1 micron of sacrificial material.

3. Etch the sacrificial material and the CMOS oxide layers down to second level metal using Mask 1.

This mask defines the contact vias from the second level metal electrodes to the solenoids. This step is shown in Fig. 188.

4. Deposit a barrier layer of titanium nitride (TiN) and a seed layer of copper.

Spin on 2 microns of resist, expose with Mask 2, and develop. This mask defines the lower -side of the solenoid square helix. The resist acts as an electroplating mold. This step is shown in Fig. 189.

6. Electroplate 1 micron of copper. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistance, which increases reliability at high current densities. This step is shown in Fig.

193.

7. Strip the resist and etch the exposed barrier and seed layers. This step is shown in Fig. 190.

8. Deposit 0. 1 microns of silicon nitride.

9. Deposit a seed layer of cobalt nickel iron alloy. CoNiFe is chosen due to a high saturation flux density of 2 Tesla, and a low coercivity. (Osaka, Tetsuya et al, A soft magnetic CoNiFe film with high saturation magnetic flux density, Nature 392, 796-798 (1998)].

Spin on 3 microns of resist, expose with Mask 3, and develop. This mask defines all of the soft magnetic parts, being the fixed magnetic pole of the solenoids, the moving poles of the linear actuator, the horizontal guides, SUB3STrITUTE SHEE (Rule 26) (RO/AU) WO "/03680 PCT/AU98/0054s 59 and the core of the ink pusher. The resist acts asan eleclroplating mold. This step is shown in Fig. 19 1.

11. Electroplate 2 microns of CoNiFe. This step is shown in Fig. 192.

12. Strip the resist and etch the exposed seed layer. This step is shown in Fig. 193.

13. Deposit 0. 1 microns of silicon nitride (Si3N 4 14, Spin on 2 microns of resist, expose with Mask 4, and develop. This mask defines the solenoid vertical wire segments, for which the resist acts as an electoplaiting mold. This step is shown in Fig. 194.

Etch the nitride down to copper using the Mask 4 resist.

16. Electroplate 2 microns of copper. This step is shown in Fig. 195.

17. Deposit a seed layer of copper.

18. Spin on 2 microns of resist, expose with Mask 5, and develop. This mask defines the upper side of the solenoid square helix. The resist acts as an electroplating mold. This step is shown in Fig. 196.

19. Electroplate 1 micron of copper. This step is shown in Fig. 197.

Strip the resist and etch the exposed copper seed layer, and strip the newly exposed resist. This step is shown in Fig. 198.

2 1. Open the bond pads using Mask 6.

22. Wafer probe. All electrical connections are complete at this point bond pads are accessible, and the chips are not yet separated.

23. DepositS5 microns of PTFE.

24. Etch the PTFE down to the sacrificial layer using Mask 7. This mask defines the ink pusher. This step is shown in Fig. 199.

Deposit 8 microns of sacrificial material. Planarize using CMP to the top of the PTFE ink pusher. This step is shown in Fig. 200.

26. Deposit 0.5 microns of sacrificial material. This step is shown in Fig. 201.

27. Etch all layers of sacrificial material using Mask 8. This mask defines the nozzle chamber wall. This step is shown in Fig. 202.

28. Deposit 3 microns of PECVD glass.

29. Etch to a depth of (approx.) I micron using Mask 9. This mask defines the nozzle rim. This step is shown in Fig. 203.

Etch down to the sacrificial layer using Mask 10. This mask defines the roof of the nozzle chamber, the nozzle, and the sacrificial etch access holes. This step is shown in Fig. 204.

3 1. Back-eth completely through the silicon wafer (with, for example, an ASE Advanced Silicon Etcher from Surface Technology Systems) using Mask 11. Continue the back-etch through the CMOS glass layers until the sacrificial layer is reached. This mask defines the ink inlets which are etched through the wafer. The wafer is also diced by this etch. This step is shown in Fig. 205.

32. Etch the sacrificial material. The nozzle chambers are cleared, the actuators freed, and the chips are separated by this etch. This step is shown in Fig. 206.

33. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply the appropriate color ink to the ink inlets at the back of the wafer. The package also includes a piezoelectric actuator attched to the rear of the ink channels. The piezoelectric actuator provides the oscillating ink pressure required for the ink jet operation.

SUBSTITUTE SHEET (Rule 26) (RO/AU) WO "/03690 WO 993680PAU9/00548 34. Connect the print heads to their interconnect system. For a low profile connection with minimum disruption of airflow, TAB may be used. Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper.

Hydrophobize the front surface of the print heads.

36. Fill the completed print heads with ink and test them. A filled nozzle is shown in Fig. 207.

Further, it would be readily understood that various other forms of construction, including substitution of various materials for other suitable materials and variations in the utilisation of nitride passivation layers will be readily evident to those skilled in the art 1 with an embodiment providing a merely illustrative example of the present invention, Description of 1J13 S In an embodiment, an ink jet nozzle chamber is provided having a shutter mechanism which open and closes over a nozzle chamber. The shutter mechanism includes a ratcheted drive which slides open and closed. The ratcheted drive is driven by a gearing mechanism which in turn is driven by a drive actuator which is activated by passing an electric current through the drive actuator in a magnetic field. The actuator force is "geared down" so as to drive a ratchet and pawl mechanism to thereby open and shut the shutter over a nozzle chanter.

Turning to Fig. 208, there is illustrated a single nozzle arrangement 1210 as shown in an open position. The nozzle arrangement 1210 includes a nozzle chamber 1212 having an anisoiropic <1Il> crystallographic etched pit which is etched down to what is originally a boron doped buried epitaxial layer 1213 which includes a nozzle rim 1214 and a nozzle ejection port 1215 which ejects ink. The ink flows in through a fluid passage 1216 when the aperture 1216 is open. The ink flowing through passage 1216 flows from an ink reservoir which operates under an oscillating ink pressure. When the shutter is open, ink is ejected from the ink ejection port 1215. The shutter mechanism includes a plate 1217 which is driven via means of guide slots 1218, 1219 to a closed position. The driving of the nozzle plate is via a latch mechanism 1220 with the plate structure being kept in a correct path by means of retainers 1222 to 1225.

The nozzle arrangement 1210 can be constructed utilising a two level poly process which can be a standard micro-electro. mechanical system production technique (MEM For a general introduction to a microelectro mechanical system (MEMS) reference is made to standard proceedings in this field including the proceedings of the SPIE (international Society for Optical Engineering), volumes 2642 and 2882 which contain the proceedings for recent advances and conferences in this field. The plate 1217 can be constructed from a first level polysilicon and the retainers 1222 to 1225 can be constructed from a lower first level poly portion and a second level poly portion, as it is more apparent from the exploded perspective view illustrated in Fig. 209.

The bottom circuit of plate 1217 includes a number of pits 1227 which are provided on the bottom surface of plate 1217 so as to reduce stiction effects.

The ratchet mechanism 1220 is driven by a gearing arrangement which includes first gear wheel 1230, second gear wheel 1231 and third gear wheel 1232. These gear wheels 1230 to 1232 are constructed utilisintg two level poly which each gear wheel being constructed around a correponding central pivot 1235 to 1237. The gears 1230 to 1232 operate to gear down the ratchet speed with the gears being driven by a gear actuator mechanism 1240.

SUBSTITUT SHET (Rule 26) (RO/ATJ) WO 99/03680 WO 993680PAU9IOOS4S 61 Turning to Fig. 209 there is illustrated an exploded perspective view of a single nozzle chamber 1210.

The actuator 1240 comprises mainly a copper circuit having a drive end 1242 which engages and drives the cogs 1243 of the gear wheel 1232. The copper portion includes serpentine sections 1245, 1246 which concertina upon movement of the end 1242. The end 1242 is actuated by means of passing an electric current through the copper portions in the presence of a magnetic field perpendicular to the surface of the wafer such that the interaction of the magnetic field and circuit result in a Lorenz force acting on the actuator 1240 so as to move the end 1242 to drive the cogs 1243. The copper portions are mounted on aluminium disks 1248, 1249 which are connected to lower levels of circuitry on the wafer upon which actuator 1240 is mounted.

Returning to Fig. 208, the actuator 1240 can be driven at a high speed with the gear wheels 1230 to 1232 i0 acting to gear down the high speed driving of actuator [240 so as to drive ratchet mechanism 1220 open and closed on demand. Hence, when it is desired to eject a drop of ink from nozzle 1215, the shutter is opened by means of driving actuator 1240. Upon the next high pressure part of the oscillating pressure cycle, ink will be ejected from the nozzle 1215. If no ink is to be ejected from a subsequent cycle, a second actuator 1250 is utilized to drive the gear wheel in the opposite direction thereby resulting in the closing of the shutter plate 1217 over the nozzle chamber 1212 resulting in no ink being ejected in subsequent pressure cycles. The pits 1227 act to reduce the forces required for driving the shutter plate 1217 to an open and closed position.

Turning to Fig. 210, there is illustrated a top cross-sectional view illustrating the various layers making up a single nozzle chamber 1210. The nozzle chambers can be formed as part of an array of nozzle chambers making up a single print head which in turn forms part of an array of print head tbricated on a semiconductor wafer in accordance with in accordance with the semiconductor wafer fibricafion techniques well known to those skilled in the art of MEMS fabrication and construction.

The bottom boron layer 1213 can be formed from the processing step of back etching a silicon wafer utilizing a buried epitaxial boron doped layer as the etch stop. Further processing of the boron layer can be undertaken so as to define the nozzle hole 1215 which can include a nozzle rim 1214.

The next layer is a silicon glass layer 1252 which normally sits on top of the boron doped layer 1213. The silicon glass layer 1252 Includes an anisotropically etched pit 1212 so as to define the structure of the nozzle chamber. On top of the silicon layer 1252 is provided a glass layer 1254 which includes the various electrical circuitry (not shown) for driving the actuators. The layer 1254 is passivated by means of a nitride layer 1256 which includes trenches 1257 for passivating the side walls of glass layer 1254.

On top of the passivation layer 1256 is provided a first level polysilicon layer 1258 which defines the shutter and various cog wheels. The second poly layer 1259 includes the various retainer mechanisms and gear wheel 1231, Next, a copper layer 1260 is provided fir defining the copper circuit actuator. The copper 1260 is interconnected with lower portions of glass layer 1254 for forming the circuit for driving the copper actuator.

The nozzle chamber 12 10 can be constructed utilizing the standard MEM5 processes including forming the various layers utilizing the sacrificial material such as silicon dioxide and subsequently sacrificially etching the lower layers away.

Subsequently, wafers that contain a series of print heads can be diced into separate print heads and a print head mounted on a wall of an ink supply chamber having a piezo electric oscillator actuator for the control of pressure in the ink supply chamnber. Ink is then ejected on demand by opening the shutter plate 1217 during periods of high oscillation pressure so as to eject ink. The nozzles being actuated by means of placing the print head in a strong SUBSTITUT SHEET (Rule 26) (RO0AU) WO 99/03680 PCT/AU98/00548 62 magnetic field utilizing pennanent magnets or electro- magnetic devices and driving current through the actuators e.g.

1240, 1250 as required to open and close the shutter and thereby eject drops of ink on demand.

One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print beads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: I. Using a double sided polished wafer deposit 3 microns of epitaxial silicon heavily doped with boron.

2. Deposit 10 microns of n/n+ epitaxial silicon. Note that the epitaxial layer is substantially thicker than required for CMOS. This is because the nozzle chambers are crystallographically etched from this layer. This step is shown in Fig. 212. Fig. 211 is a key to representations of various materials in these manufacturing diagrams. For clarity, these diagrams may not be to scale, and may not represent a cross section though any single plane of the nozzle.

3. Crystallographically etch the epitaxial silicon using, for example, KOH or EDP (ethylenediamine pyrocatchol) using MEMS Mask 1. This mask defines the nozzle cavity. This etch stops on <I l1> crystallographic planes, and on the boron doped silicon buried layer. This step is shown in Fig. 213.

4. Deposit 12 microns of low stress sacrificial oxide. Planarize down to silicon using CMP. The sacrificial material temporarily fills the nozzle cavity. This step is shown in Fig. 214.

Begin fabrication of the drive transistors, data distribution, and timing circuits using a CMOS process.

The MEMS processes which form the mechanical components of the inkjet are interleaved with the CMOS device fabrication steps. The example given here is of a 1 micron, 2 poly, 2 metal retrograde P-well process. The mechanical components are formed from the CMOS polysilicon layers. For clarity, the CMOS active components are omitted.

6. Grow the field oxide using standard LOCOS techniques to a thickness of 0.5 microns. As well as the isolation between transistors, the field oxide is used as a MEMS sacrificial layer, so inkjet mechanical details are incorporated in the active area mask. The MEMS features of this step are shown in Fig. 215.

7. Perform the PMOS field threshold implant. The MEMS fabrication has no effect on this step except in 2S calculation of the total thermal budget.

8. Perform the retrograde P-well and NMOS threshold adjust implants using the P-well mask. The MEMS fabrication has no effect on this step except in calculation of the total thermal budget 9. Perform the PMOS N-tub deep phosphorus punch through control implant and shallow boron implant.

The MEMS fabrication has no effect on this step except in calculation of the total thermal budget.

10. Deposit and etch the first polysilicon layer. As well as gates and local connections, this layer includes the lower layer of MEMS components. This includes the lower layer of gears, the shutter, and the shutter guide. It is preferable that this layer be thicker than the normal CMOS thickness. A polysilicon thickness of I micron can be used. The MEMS features of this step are shown in Fig. 215.

11. Perform the NMOS lightly doped drain (LDD) implant. This process is unaltered by the inclusion of MEMS in the process flow.

12. Perform the oxide deposition and RIE etch for polysilicon gate sidewall spacers. This process is unaltered by the inclusion of MEMS in the process flow.

13. Perform the NMOS sourceldrain implant The extended high temperature anneal time to reduce stress in the two polysilicon layers must be taken into account in the thermal budget for difsion of this implant. Otherwise, there is no effect from the MEMS portion of the chip.

SUBSTUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/00548 63 14. Perform the PMOS source/drain implant. As with the NMOS sourceldrain implant, the only effect from the MEMS portion of the chip is on thernal budget for diffusion of this implant.

Deposit 1 micron of glass as the first inter level dielectric and etch using the CMOS contacts mask. The CMOS mask for this level also contains the pattern for the MEMS inter-poly sacrificial oxide. The MEMS features of this step are shown in Fig. 216.

16. Deposit and etch the second polysilicon layer. As well as CMOS local connections, this layer includes the upper layer of MEMS components. This includes the upper layer of gears and the shutter guides. A polysilicon thickness of 1 micron can be used. The MEMS features of this step are shown in Fig. 217.

17. Deposit I micron of glass as the second interlevel dielectric and etch using the CMOS via I mask. The CMOS mask for this level also contains the pattern for the MEMS actuator contacts.

18. Metal 1 deposition and etch. Metal 1 should be non-corrosive in water, such as gold or platinum, if it is to be used as the Lorenz actuator. The MEMS features of this step are shown in Fig. 218.

19. Third interlevel dielectric deposition and etch as shown in Fig. 219. This is the standard CMOS third interlevel dielectric. The mask pattern includes complete coverage of the MEMS area.

20. Metal 2 deposition and etch. This is the standard CMOS metal 2. The mask pattern includes no metal 2 in the MEMS area.

21. Deposit 0.5 microns of silicon nitride (Si3N 4 and etch using MEMS Mask 2. This mask defines the region of sacrificial oxide etch performed in step 26. The silicon nitride aperture is substantially undersized, as the sacrificial oxide etch is isotropic. The CMOS devices must be located sufficiently far from the MEMS devices that they are not affected by the sacrificial oxide etch. The MEMS featres of this step are shown in Fig. 220.

22. Mount the wafer on a glass blank and back-etch the wafer using KOH with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer. The MEMS features of this step are shown in Fig. 221.

23. Plasma back-etch the boron doped silicon layer to a depth of I micron using MEMS Mask 3. This mask defines the nozzle rim. The MEMS features of this step are shown in Fig. 222.

24. Plasma back-etch through the boron doped layer using MEMS Mask 4. This mask defines the nozzle, and the edge of the chips. At this stage, the chips are separate, but are still mounted on the glass blank.

The MEMS features of this step are shown in Fig. 223.

Detach the chips from the glass blank. Strip the adhesive. This step is shown in Fig. 224.

26. Etch the sacrificial oxide using vapor phase etching (VPE) using an anhydrous HF/methanol vapor mixture. The use of a dry etch avoids problems with stiction. This step is shown in Fig. 225.

27. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer. The package also includes a piezoelectric actuator attached to the rear of the ink channels. The piezoelectric actuator provides the oscillating ink pressure required for the ink jet operation. The package also contains the permanent magnets which provide the I Tesla magnetic field fir the Lorenz actuators formed of metal I.

28. Connect the print heads to their interconnect systems.

29. Hydrophobize the front surface of the print heads.

Fill the completed print heads with ink and test them. A filled nozzle is shown in Fig. 226.

SUBSTrrUrE SHEET (Rule 26) (RO/AU) WO 99/03680 WO 9903680PCTIAU98100548 64 Description or 1J14 F In an embodiment, there is provided an ink jet nozzle which incorporates a plunger that is surrounded by an electromagnetic device. The plunger is made from a magnetic material such that upon activation of the magnetic device, the plunger is forced towards a nozzle outlet port thereby resulting in the ejection of ink from the outlet port.

Upon deactivation of the electomagnet, the plunger return to its rest position via the utilisation of a series of springs constructed 1o return the electromagnet to its rest position.

Fig. 227 illustrates a sectional view through a single ink jet nozzle 13 10 as constructed with an embodiment The ink jet nozzle 1310 includes a nozzle chamber 1311 which is connected to a nozzle output port 1312 for the ejection of ink. The ink is ejected by means of a tapered plunger device 1314 which is made of a soft magnetic material such as nickel-frrous material (NIFE). The plunger 1314 includes tapered end portions, e.g. 1316, in addition to intercoinnecting nitride springs, e.g. 131t7.

An electromagnetic device is constructed around the plunger 1314 and includes outer soft magnetic material 1319 which surrounds a copper current carrying wire core 1320 with a first end of the copper coil 1320 connected to a first portion of a nickel- ferrous material and a second end of the copper coil is connected to a second portion of the nickel-ferrous material. The circuit being further formed by means of vias (not shown) connecting the current carrying wire to lower layers which can take the structure of standard CMOS fabrication layers.

Upon activation of the electromagnet, the tapered plunger portions 1316 attracted to the electromagnet. The tapering allows for the forces to be resolved by means of downward movement of the overall plunger 1314, the downward movement thereby causing the ejection of ink from ink ejection port 1312. In due course, the plunger will move to a stable state having a top surface substantially flush with the electromagnet. Upon turning the power off, the plunger 1314 will return to its original position as a result of energy stored within that nitride springs 1317. The nozzle chamber 131 is refilled by inlet holes 1322 from the ink reservoir 132-3.

Turning now to Fig. 228, there is illustrated an exploded perspective of the various layers utilized in construction of a single nozzle 13 10. The bottom layer 1330 can be formed by back etching a silicon wafer which has a boron dope epitaxial layer as the etch stop. The boron dope layer 1330 can be further individually masked and etched so as to form nozzle rim 1331 and the nozzle ejection port 1312. Next, a silicon layer 1332 is fbrmed. The silicon layer 1332 can be formed as part of the original wafer having the buried boron doped layer 1330. The nozzle chamber proper can be farmed substantially from high density low pressure plasma etching of the silicon layer 1332 so as to produce substantially vertical side walls thereby fbnning the nozzle chamber. On top of the silicon layer 1332 is formed a glass layered 1333 which can include the drive and control circuitry required for driving an array of nozzles 1310. The drive and control circuitry can comprise standard two level metal CMOS circuitry innr-connected to form the copper coil circuit by means of vias though upper layers (not shown). Next, a nitride passivation layer 1334 is provided so as to passivate any lower glass layers, e.g. 1333, from sacrificial etches should a sacrificial etching he utilized in the formation of portions of the nozzle. On top of the nitride layer 1334 is formed a first nickelferrous layer 1336 followed by a copper layer 1337 and a further nickel-ferrous layer 1338 which can be formed via a dual dlamascene process. On top of the layer 1338 is fbrmed the final nitride spring layer 1340 with the springs being formed by means of semiconductor treatment of the nitride layer 1340 so as to release the springs in tension so as to thereby cause a slight rating of the plunger 1314. A number of techniques not disclosed in Fig. 228 can be utilized in the construction of various portions of the arrangement 13 10. For example, the nozzle chamber can be formed by SUBSTnVM SHEET (Rule 26) (RO/AU) WO "103680 WO 9903680PCT/AU98/00548 utilizing the aforementioned plasma etch and then subsequently filling the nozzle chamber with sacrificial material such as glass so as to provide a support for the plunger 1314 with the plunger 1314 being subsequently released via sacrificial etching of the sacrificial layers.

Further, the tapered end portions of the nickel-ferrous material can be fanned so that the utilisation of a halftone mask having an intensity pattern corresponding to the desired bottom tapered profile of plunger 1314. The halftone mask can be utilized to half-tone a resist so that the shape is transferred to the resist and subsequently to a lower layer, such as sacrificial glass an top of which is laid the nickel-ferrous material which can be finally planarised utilizing chemical mechanical planarization techniques.

3. Complete drive tranisistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal 1 5 CMOS process. This step is shown in Fig. 230. For clarity, these diagrams may not be to scale, and may not represent a cross section though any single plane of the nozzle. Fig. 229 is a key to representations of various materials in these manufacturing diagrams, and those of other cross referenced ink jet configurations.

4. Etch the CMOS oxide layers dawn to silicon or aluminum using Mask 1. This mask defines the nozzle chamber and the edges of the print heads chips.

5. Plasma etch the silicon down to the baron doped buried layer, using oxide from step 4 as a mask, This etch does not substantially etch the aluminum. This step is shown in Fig. 23 1.

6. Deposit 0.5 microns of silicon nitride (Si 3

N

4 7. Deposit 12 microns of sacrificial material.

8. Planarize down to nitride using CMP. This fills the nozzle chamber level to the chip surlhce, This step is shown in Fig. 232.

9. Etch nitride and CMOS oxide layers down to second level metal using Mask 2. This mask defines the vies for the contacts from the second level metal electrodes to the two halves of the split fixed magnetic pole. This step is shown in Fig. 233.

Deposit a seed layer of cobalt nickel iron alloy. CoNiFe is chosen due to a high saturation flux density of 2 Tesla, and a low coercivity. (Osaka Tersuya et al, A soft magnetic CoNiFe film with high saturation magnetic flux density, Nature 392, 796-798 (1998)1.

11. Spin on 5 microns of resist, expose with Mask 3, and develop. This mask defines the lowest layer of the split fixed magnetic pole, and the thinnest rim of the magnetic plunger. The resist acts as an electroplating mold. This step is shown in Fig. 234.

12. Electroplate 4 microns of CoNiFe. This step is shown in Fig. 235.

13. Deposit 0. 1 microns of silicon nitride (Si3N 4 14. Etch the nitride layer using Mask 4. This mask defines the contact vias from each end of the solenoid coil to the two halves of the split fixed magnetic pole.

Deposit a seed layer of copper.

SIJBSTITI UrI SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98100548 66 16. Spin on 5 microns of resist, expose with Mask 5, and develop. This mask defines the solenoid spiral coil and the spring posts, for which the resist acts as an electroplating mold. This step is shown in Fig. 2136.

17. Electroplate 4 microns of copper. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistance, which increases reliability at high current densities.

18. Strip the resist and etch the exposed copper seed layer. This step is shown in Fig. 237.

19. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated.

Deposit 0. 1 microns of silicon nitride. This layer of nitride provides corrosion protection and electrical insulation to the copper coil.

2 1. Etch the nitride layer using Mask 6. This mask defines the regions of continuity between the lower and the middle layers of CoNiFe.

22. Spin on 4.5 microns of resist, expose with Mask 6, and develop. This mask defines the middle layer of the split fixed magnetic pole, and the middle rim of the magnetic plunger. The resist forms an electroplating mold for these parts. This step is shown in Fig. 238.

23. Electroplate 4 microns of CoNiFe. The lowest layer of CoNiFe acts as the seed layer. This step is shown in Fig. 239.

24. Deposit a seed layer of CoNiFe.

Spin on 4.5 microns of resist, expose with Mask 7, and develop. This mask defines the highest layer of the split fixed magnetic pole and the roof of the magnetic plunger. The resist forms an electroplating mold for these pants. This step is shown in Fig. 240.

26. Electroplate 4 microns of CoNiFe. This step is shown in Fig. 24 1.

27. Deposit I micron of sacrificial material.

28. Etch the sacrificial material using Mask 8. This mask defines the contact points of the nitride springs to the split fixed magnetic poles and the magnetic plunger. This step is shown in Fig. 242.

29. Deposit 0. 1 microns of low stress silicon nitride.

Deposit 0.1 microns of high stress silicon nitride. These two layers of nitride form a pre-stressed spring which lifts the magnetic plunger out of core space of the fixed magnetic pole.

3 1. Etch the two layers of nitride using Mask 9. This mask defines the nitride spring. This step is shown in Fig. 243.

32. Mount the wafer on a glass blank and back-etch the wafer using KOH with no msk. This etch thins the wafer and stops at the buried boron doped silicon layer. This step is shown in Fig. 244.

3 3. Plasma back-etch the boron doped silicon layer to a depth of (approx.) 1 micron using Mask 10. This mask defines the nozzle rim. This step is shown in Fig. 245.

34. Plasma back-etch through the boron doped layer using Mask 11. This mask defines the nozzle, and the edge of the chips. At this stage, the chips are separate, but are still mounted on the glass blank. This step is shown in Fig. 246.

Detach the chips from the glass blank. Strip all adhesive, resist, sacrificial, and exposed seed layers.

The nitride spring is released in this step, lifing the magnetic plunger out of the fixed magnetic pole by 3 microns. This step is shown in Fig. 247.

SUBSTTUTE SHEET (Rule 26) (110/AU) WO 99103680 WO 90360P/AU9&/00548 67 36. Mount the Print howls in their packagg which May be a molded plastic former incorporating ink channels which supply diflerent colors of ink to the appropriate regions of the front surface of the wafer.

37. Connect the print heads to their interconnect systems.

38. Hydrophohize the front surface of the print heads.

39. Fill the comrpleted print heads with ink and test them. A filled nozzle is shown in Fig. 248.

Dection of115 S Inr the present invention a magnetically actuated ink jet print nozzle is provided fix the ejection of ink from an ink chamber. The magnetically actuated ink jet utilizes a linear spring to increase the travel of a shutter grill which blocks any ink pressure variations in a nozzle when in a closed position. However when the shutter is open, pressure variations are directly transmitted to the nozzle chamber and can result in the ejection of ink from the chamber. An oscillating ink pressure within an ink reservoir is used therefore to inject ink from nozzles having an open shutter grill.

In Fig. 249, there is illustrated a single nozzle mechanism 1410 of an embodiment when in a closed or rest position. The arrangement 1410 includes a shutter mechanism 1411 having shutters 1412, 1413 which are interconnected together 1415 at one end for providing structural stability. The two shutters 1412, 1413 are interconnected at another end to a moveable bar 1416 which is further connected to a stationary positioned bar 14 18 via leaf springs 1420, 1421. The bar 1416 can be made of a soft magnetic (NiFe) material.

An electromagnetic actuator is utilized to attract the bar 1416 generally in the direction 1425. The electromagnetic actuator consists of a series of soft iron claws 1424 around which is formed a copper coil wire 1426.

The electromagnetic actuators can comprise a series of actuators 1428-1430 interconnected via the copper coil windings. Hence, when it is desired to open the shutters 1412-1413 the coil 1426 is activated resulting in an attraction 1425 of bar 1416 towards the electromagnets 1428-1430. The attraction 1425 results in a corresponding interaction with linear springs 1420, 1421 and a movement of shutters 1412, 1413 to an open position as illustrated in Fig. 250, the result of the actuation being to open portals 1432, 1433 into an ink ejection chamber 1434 thereby allowing the ejection of ink through an ink ejection nozzle 1436.

The linear springs 1420, 1421 are designed to increase the movement of the shutter as a result of actuation by a factor of eight A one micron motion of the bar towards the electromnagnets will result in an eight micron sideways movement- This dramatically improves the efficiency of the system, as any magnetic field falls off strongly with distance, while the linear springs have a linear relationship between motion in one axis and the other. The use of the linear springs 1420, 1421 therefore allows the relatively large motion required to be easily achieved.

The surface of the wafer is directly immersed in an ink reservoir or in relatively large ink channels. An ultrasonic transducer (for example, a piezoelectric transducer), not shown, is positioned in the reservoir, The transducer oscillates the ink pressure at approximately 100 kI-z. The ink pressure oscillation is sufficient that ink drops would be ejected from the nozzle were it not blocked by the shutters 1412, 1413. When data signals distributed on the print head indicate that a particular nozzle is to eject a drop of ink, the drive transistor for that nozzle is turned on. This energizes the actuaors 1428-1430, which moves the shutter so that it is not blocking the ink chamber. The peak of the ink pressure variation causes the ink to be squirted out of the nozzle. As the ink presure goes negative, ink is drawn back into the nozzle, causing drop break-off. The shutter 1412, 1413 is kept open until the nozzle is refilled on the next positive pressure cycle. it is then shut to prevent the ink from being withdrawn from the nozzle on SUBSTITUT SHEET (Rule 26) (110/AU) WO "103680 WO 9903680PCT/AU98/00548 68 the next negative pressure cycle.

Each drop ejection takes two ink pressure cycles. Preferably half of the nozzles should eject drops in one phase, and the other half of the nozzle should eject drops in the other phase. This minimizes the pressure variations which occur due to a large number of nozzles being actuated.

The amplitude of the ultrasonic transducer can be Afrter altered in response to the viscosity of the ink (which is typically affected by temperature), and the number of drops which are to be ejected in a current cycle. This amplitude adjustment can be used to maintain consistent drop size in varying environmental conditions.

In Fig. 25 1, there is illustrated a section taken through the line 11 of Fig. 250 so as to illustrate the nozzle chamber 1434 which can be formed utilizing an anisotropic crystallographic etch of the silicon substrate. The etch access through the substrate can be via the slots 1432,1422 (Fig. 250) in the shutter grill.

The device is manufactured on <100> silicon with a buried boron etch stop layer 1440, but rotated 450 in relation to the <01 0> and COO01> planes. Therefore, the <1lIi> planes which stop the crystallographic etch of the nozzle chamber form a 450 rectangle which superscribes the slots in the fixed grill. This etch will proceed quite slowly, due to limited access of etchant to the silicon. Howeve, the etch can be performed at the same time as the bulk silicon etch which thins the bottom of the wafer.

In Fig. 252, there is illustrated an exploded perspective of the various layers formed in the construction of an ink jet print head 1410D. The layers include the boron doped layer 1440 which acts as an etched stop and can be derived from back etching a silicon wafer having a buried epitaxial layer as is well known in Micro Electro Mechanical Systems (MEMS). For a general introduction to a micro-electro mechanical system (MEMS) reference is made to standard proceedings in this field including the proceedings of the SPIE (International Society for Optical Engineering), volumes 2642 and 2882 which contain the proceedings for recent advances and conferences in this field. The nozzle chambers side walls are formed from a crystallograhic graphic etch of the wafer 1441 with the boron doped Layer 1440 being utilized as an etch stop.

A subsequent layer 1442 is constructed for the provision of drive transistors and printer logic and can comprise a two level metal CMOS processing layer 1442. The CMOS processing layer is covered by a nitride layer 1443 which includes portions 1444 which cover and protect the side walls of the CMOS layer 1442. The copper layer 1445 can be constructed utilizing a dual damascene process. Finally, a soft metal (NiFe) layer 1446 is provided for forming the rest of the actuator. Each of the layers 1444, 1445 are separately coated by a nitride insulating layer (not shown) which provides passivation and insulation and can be a standard 0.1lJLtm process.

The arrangement of Fig. 249 therefore provides an ink jet nozzle having a high speed firing rate (approximately 50 kHz) which is suitable for fabrication in arrays of ink jet nozzles, one along side another, for fabrication as a monolithic page width print head.

One form of detailed manufacturing process which can be used to faibricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer deposit 3 microns of epitaxial silicon heavily doped with boron.

3. Complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process. Relevant features of the wafer at this step are shown in Fig. 254. For clarity, these diagrams may not be to scale, and may not represent a cross section tough any single plane of the nozzle. Fig. 253 is a key to SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99103690 WO 9903680PCT/AU9S/00548 69 representations of various materials in these manufacturing diagrams, and those of other cross referenced ink jet configurations.

4. Etch the CMAOS oxide layers down to silicon or aluminum using Mask 1. This mask defines the nozzle chamber, and the edges of the print head chips. This step is shown in Fig. 255.

5. Crystallographically etch the exposed silicon using, for example, KOH or EDP (ethylenedianine pyrocatechol). This etch stops on <1Il> crystallographic planes, and on the boron doped silicon buried layer. This step is shown in Fig. 256.

6. Deposit 12 microns of sacrificial material. Planarize down to oxide using CMP. The sacrificial material temporarily fills the nozzle cavity. This step is shown in fig. 257.

7. Deposit 0.5 microns of silicon nitride (Si3N4).

8. Etch nitride and oxide down to aluminumn or sacrificial material using Mask 3. This mask defines the contact vis from the aluminum electrodes to the solenoid, as well as the fixed grillI over the nozzle cavity. This step is shown in Fig. 258.

9. Deposit a seed layer of copper. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistance, which increases reliability at high current densities.

Spin on 2 microns of resist. expose with Mask 4, and deveiop. This mask defines the lower side of' the solenoid square helix. The resist acts as an electroplating mold. This step is shown in Fig. 259.

11. Electroplate 1 micron of copper. This step is shown in Fig. 260.

12. Strip the resist and etch the exposed copper seed layer. This sLt is shown in Fig. 26 1.

13. Deposit 0. 1 microns of silicon nitride.

14. Deposit 0.5 microns of sacrificial material.

Etch the sacrificial material down to nitride using Mask 5. This mask defines the solenoid, the fixed magnetic pole, and the linear spring anchor. This step is shown in Fig. 262.

16. Deposit a seed layer of cobalt nickel iron alloy. CoNiFe is chosen due to a high saturation flux density of 2 Tesla, and a low coercivity. [Osa"a Tetsuya et al, A soft magnetic CoNiFe film with high saturation magnetic flux density, Nature 392, 796-798 (1998)].

17. Spin on 3 microns of resist, expose with Mask 6, and develop. This mask defines all of the soft magnetic parts, being the U shaped fixed magnetic poles, the linear spring, the linear spring anchor, and the shutter grill. The resist acts as an electroplating mold. This step is shown in Fig, 263.

18. Electroplate 2 microns of CoNiFe. This step is shown in Fig. 264.

19. Strip the resist and etch the exposed seed layer. This step is shown in Fig. 265.

Deposit 0. 1 microns of silicon nitride (Si 3

N

4 21. Spin on 2 microns of resist expose with Mask 7, and develop. This mask defines the solenoid vertical wire segments, for which the resist acts as an electroplating mold. This step is shown in Fig, 266.

22. Etch the nitride down to copper using the Mask 7 resist.

23. Electroplate 2 microns of copper. This step is shown in Fig. 267, 24. Deposit a seed layer of copper.

Spin on 2 microns of resist, expose with Mask 8, and develop. This mask defines the upper side of the solenoid square helix. The resist acts as an electroplating mold. This step is shown in Fig. 26.

SUBSTriTT SKEET (Rule 26) (110/AUF) WO "/03680 WO 9903680PCT/AU9S/00548 26. Electroplate 1 microrn of copper. This step is shown in Fig. 269.

27. Strip the resist end etch the exposed copper seed layer, and strip the newly exposed resist This step is shown in Fig. 270.

28. Deposit 0. 1 microns of conformal silicon nitride as a corrosion baffler.

29. Open the bond pads using Mask 9.

Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated.

3 1. Mount the wakfr on a glass blank and back-etch the wafer using KOH with no mask. This etch tins the wafer and stops at the buried boron doped silicon layer. This step is shown in Fig. 271.

32. Plasma back-etch the boron doped silicon layer to a depth of I micron using Mask 9. This mask defines the nozzle rim. This step is shown in Fig. 272.

33. Plasma back-etch trough the boron doped layer using Mask 10. This mask defines the nozzle, and the edge of the chips. At this stage, the chips are separate, but are still mounted on the glass blank. This step is shown in Fig. 273.

34. Detach the chips from the glass blank. Strip all adhesive, resist, sacrificial, and exposed seed layers. This step is shown in Fig. 274.

Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer. The package also includes a piezoelectric actuator attached to the rear of the ink channels. The piezoelectric actuator provides the oscillating ink pressure required fir the ink jet operation.

36. Connect the print heads to their interconnect systems.

37. Hydrophobize the front surface of the print heads.

38. Fill the completed print heads with ink and test them. A filled nozzle is shown in Fig. 275.

DecipineofIJ6 F An embodiment utilizes a Lorenz force on a current carrying wire in a magnetic field to actuate a diaphragm for the injection of ink from a nozzle chamber via a nozzle hole. The magnetic field is static and is provided by a permanent magnetic yoke around the nozzles of an ink jet head, Referring initially to Fig, 276, there is illustrated a single ink jet nozzle chamber apparatus 15 10 as constructed in accordance with an embodiment. Each ink jet nozzle 1510 includes a diaphragm 1511 of a corrugated form which is suspended over a nozzle chamber having a ink port 1513 for the injection of ink. The diaphragm 1511 is constructed from a number of layers including a plane copper coil layer which consists of a large number of copper coils which formn a circuit for the flow of electric current across the diaphragm 15 11. The electric current in the wires of the diaphragm coil section 15 11 all flowing in the same direction. Fig. 283 is a perspective view of the current circuit utilised in the construction of a single ink jet nozzle, illustrating the corrugated structure of the traces in the diaphragm 1511 of Fig. 276. A permanent magnetic yoke (not shown) is arranged so that the magnetic field 1516, is in the plane of the chip's surface, perpendicular to the direction of current flow across the diaphragm coil 15 11.

In Fig. 277, there is illustrated a sectional view of the ink jet nozzle 15 10 taken along the line A-AlI of Fig. 276 when the diaphragm 1511 has been activated by current flowing through coil wires 1514. The SUBSTITUTE SHEE (Rule 26) (ROAU) WO 99/03680 W099/3680PCT/AU98100548 71 diaphragm 1511 is forced generally in the direction of nozzle 1513 thereby resulting in ink within chamber I518 being ejected out of port 1513. The diaphragm 1511 and chamber 1518 are connected to an ink reservoir 1519 which, after the ejection of ink via port 1513, results in a refilling of chamber 1518 from ink reservoir 1519.

The movement of the diaphragm 1511 results from a Lorenz interaction between the coil current and the magnetic field, The diaphragm 1511 is corrugated so that the diaphragm motion occurs as an elastic bending motion.

This is important as a flat diaphragm may be prevented from flexing by tensile stress.

When data signals distributed on the print head indicate that a particular nozzle is to eject a drop of ink, the drive transistor for that nozzle is turned on. This energises the coil 1514, causing elastic defrmation of the diaphragm 1511 downwards, ejecting ink. After approximately 3 ias, the coil current is turned off, and the diaphragm 1511 returns to its quiescent position. The diaphragm return 'sucks' some of the ink back into the nozzle, causing the ink ligament connecting the ink drop 1520 to the ink in the nozzle to thin. The forward velocity of the drop and backward velocity of the ink in the chamber 1518 are resolved by the ink drop 2520 breaking off from the ink in the nozzle. The ink drop 1520 then continues towards the recording medium. Ink refill of the nozzle chamber 1518 is via the two slots 1522, 1523 at either side of the diaphragm. The ink refill is caused by the surface tension of the ink meniscus at the nozzle, Turning to Fig. 278. the corrugated diaphragm can be formed by depositing a resist layer 1530 on top of a sacrificial glass layer 1531. The resist layer 1530 is exposed utilising a mask 1532 having a halftone pattern delineating the corrugations.

After development, as is illustrated in Fig. 279, the resist 1530 contains the corrugation pattern. The resist layer 1530 and the sacrificial glass layer are then etched utilizing an etchant that erodes the resist 1530 at substantially the same rate as the sacrificial glass 15 31. This transfers the corrugated pattern into the sacrificial glass layer 153 1 as ililustrated in Fig. 280. As illustrated in Fig. 28 1, subsequently, a nitride passivation layer 1534 is deposited followed a copper layer 1535 which is patterned utilizing a coil mask. A futher nitride passivation layer 1536 follows on top of the copper layer 1535. Slots 1522, 1523 in the nitride layer at the side of the diaphragm can be etched (Fig. 276) and subsequently, the sacrificial glass layer can be etched away leaving the corrugated diaphragm.

In Fig. 282, there is illustratedi an exploded perspective view of the various layers of an ink jet nozzle 15 which is constructed on a silicon wafer having a buried boron doped epitaxial layer 1540 which is back etched in a final processing step, including the etching of ink port 1513. The silicon substrate 1541, as will be discussed below, is an anisotropically crystailographically etched so as to form the nozzle chamber structure. On top of the silicon substrate layer 1541 is a CMOS layer 1542 which can comprise standard CMOS processing to Ibm two level metal drive and control circuitry. On top of the CMOS layer 1542 is a first passivation layer which can comprise silicon nitride which protects the lower layers from any subsequent etching processes. On top of this layer is formed the copper layer 1545 having through holes eg. 1546 to the CMOS layer 1542 for the supply of current. On top of the copper layer 1545 is a second nitrate passivation layer 1547 which provides for protection of the copper layer from ink and provides insulation.

The nozzle 15 10 can be formed as part of an array of nozzles formed on a single wafer, After construction, the wafer creating nozzles 15 10 can be bonded to a second ink supply wafer having ink channels for the supply of ink such that the nozzle 15 10 is effctively supplied with an ink reservoir on one side and ejects ink through the hole 1513 onto print media or the like on demand as required.

SUBSTrnJM SHEE (Rule 26) (RO/AU) WO "9/03680 PCT/AU98S/00548 72 The nozzle chamber 1518 is fbrmed using an anisotropic crystallographic etch of the silicon substrate.

Etchant access to the substrate is via the slots 1522, 1523 at the sides of the diaphragm. The device is manufactured on <100> silicon (with a buried boron etch stop layer), but rotated 450 in relation to the <010> and <001> planes.

Therefore, the <1 I I> planes which stop the crystallographic etch of the nozzle chamber form a 450 rectangle which superscribes the slot in the nitride layer. This etch will proceed quite slowly, due to limited access of etchant to the silicon. However, the etch can be performed at the same time as the bulk silicon etch which thins the wafer. The drop firing rate is around 7 kHz. The ink jet head is suitable for fabrication as a monolithic page wide print head.

The illustration shows a single nozzle of a 1600 dpi print head in 'down shooter configuration.

3. Complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process. This step is shown in Fig. 285. For clarity, these diagrams may not be to scale, and may not represent a cross section though any single plane of the nozzle. Fig. 284 is a key to representations of various materials in these manufacturing diagrams, and those of other cross referenced ink jet configurations.

4. Etch the CMOS oxide layers down to silicon or aluminum using Mask 1. This mask defines the nozzle chamber, and the edges of the print heads chips. This step is shown in Fig. 286.

5. Crystal ographically etch the exposed silicon using, for example, KOH or EDP (ethylenediamine pyrocatechol). This etch stops on <111> crystallographic planes, and on the boron doped silicon buried layer. This step is shown in Fig. 287.

6. Deposit 12 microns of sacrificial material (polyimide). Planarize down to oxide using CMP, The sacrificial material temporarily fills the nozzle cavity. This step is shown in Fig. 288.

7. Deposit 1 micron of (sacrificial) photosensitive polyimide.

8. Expose and develop the photosensitive polyimide using Mask 2. This mask is a gray-scale mask which defines the concertina ridges of the flexible membrane containing the central part of the solenoid. The result of the etch is a series of triangular ridges across the whole length of the ink pushing membrane. This step is shown in Fig.

289.

9. Deposit 0.1 microns of PECVD silicon nitride (Si3N 4 Etch the nitride layer using Mask 3. This mask defines the contact vias from the solenoid coil to the second-level metal contacts.

11. Deposit a seed layer of copper.

12. Spin on 2 microns of resist, expose with Mask 4, and develop. This mask defines the coil of the solenoid. The resist acts as an electroplating mold. This step is shown in Fig. 290.

13. Electroplate 1 micron of copper. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigration resistance, which increases reliability at high current densities.

14. Strip the resist and etch the exposed copper seed layer. This step is shown in Fig, 291.

Deposit 0.1 microns of silicon nitride (Si3N 4 SUBSITrJTE SHEET (Rule 26) (RO/AU) WO 99/03680 PC1/AU98/0&10548 73 16. Etch the nitride lyr using Mask 5. This m k te the edes of the ink pushing mnbrane and the bond pads.

17. Wafer probe. All electrical connections an complete at this point, bond pads accessible, and the chips arc not yet separated.

18. Mount the wafer on a glass blank and back-etch the wafer using KOH with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer. This step is shown in Fig. 292.

19. Plasma back-etch the boron doped silicon layer to a depth of I micron using Mask 6. This mask defines the nozzle rim. This step is shown in Fig. 293.

Plasma back-etch through the boron doped layer using Mask 7. This mask defines the nozzle, and the edge of the chips. At this stage, the chips are still mounted on the glass blank. This step is shown in Fig. 294.

21. Strip the adhesive layer to detach the chips from the glass blank. Etch the sacrificial layer. This process completely separates the chips. This step is shown in Fig. 295.

22. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer.

23. Connect the print heads to their interconnect systems.

24. Hydrophobize the front surface of the print heads.

Fill with ink, apply a strong magnetic field in the plane of the chip surface, and test the completed print beads. A filled nozzle is shown in Fig. 296.

Description of IJ25 F In an embodiment, there is provided a nozzle chamber having an ink ejection port and a magnetostrictive actuator surrounded by an electrical coil such that, upon activation of the coil, a magnetic field is produced which effects the actuator to the extent that it causes the ejection of ink from the nozzle chamber.

Turning now to Fig. 297, there is illustrated a perspective cross-sectional view, of a single inkjet nozzle arrangement 2410. The nozzle arrangement includes a nozzle chamber 2411 which opens to a nozzle ejection port 2412 for the ejection of ink.

The nozzle 2410 can be formed on a large silicon wafer with multiple print heads being formed from nozzle groups at the same time. The nozzle port 2412 can be formed from back etching the silicon wafer to the level of a boron doped epitaxial layer 2413 which is subsequently etched utilizing an appropriate mask to form the nozzle portal 2412 including a rim 2415. The nozzle chamber 2411 is futher formed fiom a crystallographic etch of the remaining portions of the silicon wafer 2416, the crystallographic etching process being well known in the field of microelectro-mechanical systems (MEMS). For a general introduction to a micro-electro mechanical system (MEMS) reference is made to standard proceedings in this field including the proceedings of the SPIE (International Society for Optical Engineering), volumes 2642 and 2882 which contain the proceedings for recent advances and conferences in this field.

Turning now to Fig. 298 there is illustrated an exploded perspective view illustrating the construction of a single ink jet nozzle arrangement 2410 in accordance with an embodiment.

On top of the silicon wafer 2416 there is previously constructed atwo level metal CMOS layer 2417 which includes an aluminum layer (not shown). The CMOS layer 2417 is constructed to provide data and control circuitry for -the ink jet nozzle 2410. On top of the CMOS layer 2417 is constructed a nitride passivation layer 2420 which SUBSTIJUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/00548 74 includes nitride paddle portion 2421. The nitride layer 2421 can be constructed by a utilizing a sacrificial material such as glas to first fill the crystalographic etched nozzle chamber 2411 then depositing the nitride layer 2420, 2421 before etching the sacrificial layer away to release the nitride layer 2421. On top ofthe nitride layer 2421 is formed a Terfenol-D layer 2422. Terfenol-D is a material having high magnetostrictive properties (for further information on the properties of Terfnol-D, reference is made to "magnetostriction, theory and applications of magnetoelasticity" by Etienne du Trmolett de Lachiesscric published 1993 by CRC Press). Upon it being subject to a magnetic field, the Terfenol-D substance expands. The Terfnol-D layer 2422 is attached to a lower nitride layer 2421 which does not undergo expansion. As a result the forces are resolved by a bending of the nitride layer 2421 towards the nozzle ejection bole 2412 thereby causing the ejection of ink from the ink ejection portal 2412.

The Terfenol-D layer 2422 is passivated by a top nitride layer 2423 on top of which is a copper coil layer 2424 which is interconnected to the lower CMOS layer 2417 via a series of vias so that copper coil layer 2424 can be activated upon demand. The activation of the copper coil layer 2424 induces a magnetic field 2425 across the Terfenol-D layer 2422 thereby causing the Terfenol-D layer 2422 to undergo phase change on demand. Therefore, in order to eject ink from the nozzle chamber 2411, the Terfenol-D layer 2422 is activated to undergo phase change causing the bending ofthe actuator 2426 (Fig. 297) in the direction of the ink ejection port 2412 thereby causing the ejection of ink drops. Upon deactivation of the upper coil layer 2424 the actuator 2426 (Fig. 297) returns to its quiescent position causing some of the ink back into the nozzle chamber causing the ink ligament connecting the ink drop to the ink in the nozzle chamber to thin. The forward velocity of the drop and backward velocity of the ink in the nozzle chamber 2411 are resolved by the ink drop breaking off from the ink in the nozzle chamber 2411. Ink refill of the nozzle chamber 2411 is via the sides of actuator 2426 (Fig. 297) as a result of the surface tension of the ink meniscus at the ejection port 2412.

The copper layer 2424 is passivated by a nitride layer (not shown) and the nozzle arrangement 2410 abuts an ink supply reservoir 2428 (Fig. 297).

One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer deposit 3 microns ofepitaxial silicon heavily doped with boron.

2. Deposit 20 microns of epitaxial silicon, either p-type or n-type, depending upon the CMOS process used.

3. Complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process. The metal layers an copper instead of aluminum, due to high current densities and subsequent high temperature processing. Relevant features of the wafer at this step are shown in Fig. 300. For clarity, these diagrams may not be to scale, and may not represent a cross section though any single plane ofthe nozzle. Fig. 299 is a key to representations of various materials in these manufacturing diagrams, and those of other cross referenced ink jet configurations.

4. Etch the CMOS oxide layers down to silicon using Mask 1. This mask defines the nozzle chamber. This step is shown in Fig. 301.

Deposit I micron of low stress PECVD silicon nitride (Si3N4).

6. Deposit a seed layer of Terfnol-D.

7. Deposit 3 microns of resist and expose using Mask 2. This mask defines the actuator beams. The resist forms a mold for electroplating ofthe Terfenol-D. This step is shown in Fig. 302.

SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/00548 S. Electroplate 2 microns of Trfenol-D.

9. Strip the resist and etch the seed layer. This step is shown in Fig. 303.

Etch the nitride layer using Mask 3. This mask defin the ctuator beams and the ozle chamber, as well as the contact vias from the solenoid coil to the second-level metal contacts. This step is shown in Fig. 304.

11. Deposit a seed layer of copper.

12. Deposit 22 microns of resist mad expose using Mask 4. This mask defines the solenoid, and should be exposed using an x-ray proximity mask, as the aspect ratio is very large. The resist forms a mold for electroplating of the copper. This step is shown in Fig. 305.

13. Electroplate 20 microns of copper.

14. Strip the resist and etch the copper seed layer. Steps 0 to 13 form a LIGA process. This step is shown in Fig. 306.

Crystallographically etch the exposed silicon using, for example, KOH or EDP (ethylenediamine pyrocatechol). This etch stops on <111> crystalographic planes, and on the boron doped silicon buried layer. This step is shown in Fig. 307.

16. Deposit 0.1 microns of ECR diamond like carbon (DLC) as a corrosion barrie (not shown).

17. Open the bond pads using Mask 18. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated.

19. Mount the wafer on a glass blank and back-etch the wafer using KOH with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer. This step is shown in Fig. 308.

Plasma back-etch the boron doped silicon layer to a depth of I micron using Mask 6. This mask defines the nozzle rim. This step is shown in Fig. 309.

21. Plasma back-etch though the boron doped layer using Mask 6. This mask defines the nozzle, and the edge of the chips. Etch the thin ECR DLC layer through the nozzle hole. This step is shown in Fig. 310.

22. Strip the adhesive layer to detach the chips from the glass blank.

23. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer.

24. Connect the print heads to their interconnect systems.

Hydrophobize the front surface of the print heads.

26. Fill the completed print heads with ink and test them. A filled nozzle is shown in Fig. 311.

Description of IJ26 F In an embodiment, shape memory materials are utilized to construct an actuator suitable for injecting ink from the nozzle of an ink chamber.

Turning to Fig. 312, there is illustrated an exploded perspective view 2510 of a single ink jet nozzle as constructed in accordance with an embodiment. The ink jet nozzle 2510 is constructed from a silicon wafer base utilizing back etching of the wafer to a boron doped epiaxial layer. Hence, the inkjet nozzle 2510 comprises a lower layer 2511 which is constructed from boron doped silicon. The boron doped silicon layer is also utilized a crystallographic etch stop layer. The next layer comprises the silicon layer 2512 that includes a crystallographic pit 2513 having side walls etch at the usual angle of 54.74. The layer 2512 also includes the various required circuitry SUBSSTrrE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/O0548 76 and transistors for example, CMOS layer (not shown). After this, a 0.5 micron thick thermal silicon oxide layer 2515 is grown on top of the silicon wafer 2512.

After this, comes various layers which can comprise a two level metal CMOS process layers which provide the metal interconnect for the CMOS transistors formed within the layer 2512. The various metal pathways etc. are not shown in Fig. 312 but for two metal interconnects 2518, 2519 which provide interconnection between a shape memory alloy layer 2520 and the CMOS metal layers 2516. The shape memory metal layer is next and is shaped in the form of a serpentine coil to be heated by end interconnectvia portions 2521,2523. A top nitride layer 2522 is provided for overall passivation and protection of lower layers in addition to providing a means of inducing tensile stress to curt upwards the shape memory alloy layer 2520 in its quiescent state.

An embodiment relies upon the thermal transition of a shape memory alloy 2520 (SMA) from its martensitic phase to its austenitic phase. The basis of a shape memory effect Is a martensiic tansformation which creates a polydemane phase upon cooling. This polydemane phase accommodates finite reversible mechanical deformations without significant changes in the mechanical self energy of the system. Hence, upon re-transformation to the austenitic state the system returns to its former macroscopic state to displaying the well known mechanical memory.

The thermal transition is achieved by passing an electrical current through the SMA. The actuator layer 2520 is suspended at the entrance to a nozzle chamber 2513 connected via leads 2518,2519 to the lower layers.

In Fig. 313, there is shown a cross-section of a single nozzle 2510 when in its quiescent state, the section basically being taken through the line A-A of Fig. 312. The actuator 2530 is bent away from the nozzle when in its quiescent state. In Fig. 314, there is shown a corresponding cross-section for a single nozzle 2510 when in an actuated state. When energized, the actuator 2530 straightens, with the corresponding result that the ink is pushed out of the nozzle. The process of energizing the actuator 2530 requires supplying enough energy to raise the SMA above its transition temperature, and to provide the latent heat of transformation to the SMA 2520.

Obviously, the SMA martensitic phase must be pre-stressed to achieve a differnt shape from the austenitic phase. For print heads with many thousands of nozzles, it is important to achieve this pre-stressing in a bulk manner.

This is achieved by depositing the layer of silicon nitride 2522 using Plasma Enhanced Chemical Vapor Deposition (PECVD) at around 300 0 C over the SMA layer. The deposition occurs while the SMA is in the austenitic shape.

After the print head cools to room temperature the substrate under the SMA bend actuator is removed by chemical etching of a sacrificial substance. The silicon nitride layer 2522 is under tensile stress, and causes the actuator to curl upwards. The weak martensitic phase of the SMA provides little resistance to this curl. When the SMA is heated to its austenitic phase, it returns to the flat shape into which it was annealed during the nitride deposition. The transformation being rapid enough to result in the ejection of ink from the nozzle chamber.

There is one SMA bend actuator 2530 for each nozzle. One end 2531 of the SMA bend actuator is mechanically connected to the substrate. The other end is free to move under the stresses inherent in the layers.

Returning to Fig. 312 the actuator layer is therefore composed of three layers: I. AnSiO 2 lower layer2515. This layer acts asasress 'reference' for the nitride tensile layer. Italso protects the SMA from the crystallographic silicon etch that forms the nozzle chamber. This layer can be formed as part of the standard CMOS process for the active electronics of the print head.

2. A SMA heater layer 2520. A SMA such as nickel titanium (NiTi) alloy is deposited and etched into a serpentine form to increase the electrical resistance.

SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/00548 77 3. A silicon nitride top layer 2522. This is a thin layer of high stiffniess which is deposited using PECVD. The nitride stoichiometry is adjusted to achieve a layer with ipificant tensile stress at room temperature relative to the SiO 2 lower layer. s purpose is to bend the actuator at the low teamperature martensitic phase.

As noted previously the ink jet nozzle of Fig. 312 can be constructed by utilizing a silicon wafer having a buried boron epitaxial layer. The 0.5 micron thick dioxide layer 2515 is then formed having side slots 2545 Which are utilized in a subsequent crystallographic etch. Next, the various CMOS layers 2516 are formned including drive and control circuitry (not shown). The SMA layer 2520 is then created on top of layers 2515/2516 and being interconnected with the drive circuitry. Subsequently, a silicon nitride layer 2522 is formed on top. Each of the layers 2515, 2516, 2522 include the various slots eg. 2545 which are utilized in a subsequent crystallographic etch.

The silicon wafer is subsequently thinned by means of back etching with the etch stop being the boron layer 2511.

Subsequent boron etching forms the nozzle hole eg. 2547 and rim 2546 (Pig. 314). Subsequently, the chamber proper is formed by means of a crystallographic etch with the slots 2545 defining the extent of the etch within the silicon oxide layer 2512.

A large array of nozzles can be formed on the same wafer which in trn is attached to an ink chamber for filling the nozzle chambers.

One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: I. Using a double sided polished wafer deposit 3 microns of epitaxial silicon heavily doped with boron.

3. Complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process. This step is shown in Fig. 316. For clarity, these diagrams may not be to scale, and may not represent a cross section though any single plane of the nozzle. Fig. 315 is a key to representations of various materials in these manufacturing diagrams, and those of other cross referenced inkjet configurations.

4. Etch the CMOS oxide layers down to silicon or aluminum using Mask 1. This mask defines the nozzle chamber, and the edges of the print heads chips. This step is shown in Fig. 317.

Crystallographicaily etch the exposed silicon using, for example, KOH or EDP (ethylenediamine pyrocatechol). This etch stops on <111> crystallographic planes, and on the boron doped silicon buried layer. This step is shown in Fig. 318.

6. Deposit 12 microns of sacrificial material. Planarize down to oxide using CMP. The sacrificial material temporarily fills the nozzle cavity. This step is shown in Fig. 319.

7. Deposit 0.1 microns of high sutress silicon nitride (Si 3 N4).

8. Etch the nitride layer using Mask 2. This mask defines the contact vias from the shape memory heater to the second-level metal contacts.

9. Deposit a seed layer.

Spin on 2 microns of resist, expose with Mask 3, and develop. This mask defines the shape memory wire embedded in the paddle. The resist acts as an electroplating mold. This step is shown in Fig. 320.

11. Electroplate 1 micron of Nitinol. Nitinol is a 'shape memory' alloy of nickel and titanium, developed at the Naval Ordnance Laboratory in the US (hence Ni-Ti-NOL). A shape memory alloy can be thermally switched between its weak marensitic state and its high stifflhess austenic state.

SUBSTITrTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU9Io0040 78 12. Strip the resist and etch the expoed seed lay This sup is shown in Fig. 321.

13. Wafer probe, All electrical connections e complete at this point, bond pads are accessible, and the chips are not yet separated.

14. Deposit 0.1 microns of high stress silicon nitride. High stress ide is used so that once the sacrificial material is etched, and the paddle is released, the stress in the nitride layer will bend the relatively weak martensitic phase of the shape memory alloy. As the shape memnoty alloy in its austenic phase is flat when it is annealed by the relatively high temperature deposition of this silicon nitride layer, it will return to this flat state when electrothermally heated.

Mount the wafer on a glass blank and back-etch the wafer using KOH with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer. This step is shown in Fig. 322.

16. Plasma back-etch the boron doped silicon layer to a depth of I micron using Mask 4. This mask defines the nozzle rim. This step is shown in Fig. 323.

17. Plasma back-etch through the boron doped layer using Mask 5. This mask defines the nozzle, and the edge of the chips. At this stage, the chips are still mounted on the glass blank. This step is shown in Fig. 324.

13. Strip the adhesive layer to detach the chips from the glass blank. Etch the sacrificial layer. This process completely separates the chips. This step is shown in Fig. 325.

19. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the fiont surface of the wafer.

Connect the print heads to their interconnect systems.

21. Hydrophobize the fiont surface of the print he&s& 22. Fill with ink and test the completed print heads. A filled nozzle is shown in Fig. 326.

Description of IJ45 F In an embodiment, an ink jet print head is constructed from a series of nozzle arrangements where each nozzle arrangement includes a magnetic plate actuator which is actuated by a coil which is pulsed so as to move the magnetic plate and thereby caes the ejection of ink. The movement of the magnetic plate results in a leaf spring device being extended resiliently such that when the coil is deactivated, the magnetic plate returns to a rest position resulting in the ejection of a drop of ink from an aperture created within the pase.

Turning now to Fig. 327 to Fig. 329, there will now be explained the operation of this embodiment Turning to Fig. 327, there is illustrated an ink jet nozzle arrangement 4401 which includes a nozzle chamber 4402 which connects with an ink ejection nozzle 4403 such that, when in a quiescent position, an ink meniscus 4404 forms over the nozzle 4403. The nozzle 4403 is formed in a magnetic nozzle plate 4405 which can be constructed from a ferrous material. Attached to the nozzle plate 4405 is a series of leaf springs e.g. 4406, 4407 which bias the nozzle plate 4405 away from a base plate 4409, Between the nozzle plate 4405 and the base plate 4409, there is provided a conductive coil 4410 which is interconnected and controlled via a lower circuitry layer 4411 which can comprise a standard CMOS circuitry layer. The ink chamber 4402 is supplied with ink from a lower ink supply channel 4412 which is formed by etching through a wafer substrate 4413. The wafer substrate 4413 can comprise a semiconductor wafer substrate. The ink chamber 4402 is interconnected to the ink supply channel 4412 by means of a series of slots 4414 which can be etched through the CMOS layer 4411.

SUBSTITUTE SHEET (Rule 26) (RO/AU) WO "103690 WO 9903680PCT/AU9S00548 79 mhe are around the coil 4410 is hydrophobically treated so that during operation, a small meniscus e.

4416, 4417 forms between the nozzle plate 4405 and base plate 4409.

when it is desired to eject a drop of ink, the coil 4410 is mnergised. This results in "a movement of the plate 4405 as illustrated in Fig. 328, The general downward movment of the pla 4405 results in a substantial increase in pressure within nozzle chamber 4402. The increase in pressur e results in a rapid growth in the meniscus 4404 as ink flows out of the nozzle chamber 4403. The movement of the plate 4405 also results in the springs 4406, 4407 undergoing a general resilient extension. The small width of the slot 4414 results in minimal outflows of ink into the nozzle chamber 4412.

Momsents late, as illustrated in Fig. 329, the coil 4410 is deactivated resulting in a return of the plate 4405 towards its quiescent position as a result of the springs 4406, 4407 acting on the nozzle plat 4405. The return of the nozzle plate 4405 to its quiescent position results i a rapid decrease in pressure within the nozzle chamber 4402 which in turn results in a general back flow of ink around the ejection nozzle 4403. The forward momentum of the ink outside the: nozzle plate 4403 and the back suction of the ink around the ejection nozzle 4403 results in a drop 4419 being formed and breaking off so as to continue to the print media.

The surface tension characteristics across the nozzle 4403 result in a general inflow of ink from the ink supply charnel 4412 until such time as the quiescent position of Fig. 327 is again reached. In this manner, a coil actuated magnetic ink jet print head is formed for the adoption of ink drops on demand. Importantly, the area around the coil 4410 is hydrophobicaly treated so as to expel any ink firm flowing into this area.

Turning now to Fig. 330, there is illustrated a side perspective view, partly in section of a single nozzle arrangement constructed in accordance with the principles as previously outlined with respect to Fig. 327 to Fig, 329.

The arrangement 4401 includes a nozzle plate 4405 which is formed around -n ink supply chamber 4402 and inicludes an ink ejection nozzle 4403. A series of leaf spring elements 4406-4408 are also provided which can be formed from the same material as the nozzle plat 4405. A base plate 4409 also is provided for encompassing the coil 4410. The wafer 4413 includes a series of slots 4414 for the wicking and flowing of ink into nozzle chamber 4402 with the nozzle chamber 4402 being interconnected via the slots with an ink supply channel 4412. The slots 4414 are of a thin elongated form so as to provide for fluidic resistance to a rapid outflow of fluid 11cm the chamber 4402.

The coil 4410 is conductive interconnected at a predetermined portion (not shown) with a lower CMOS layer for the control and driving of the coil 4410 and movemnent of base plate 4405. Alternatively, the plate 4409 can be broken into two separate semi- circular plates; and the coil 4410 can have separate ends connected through one of the semi circular plates through to a lower CMOS layer.

Obviously, an aray of ink jet nozzle devices con be formed at a time on a single silicon wafer so as to form multiple printheads.

One form of detailed manufturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps: 1. Using a double sided polished wafer, complete a 0.5 micron, one poly, 2 metal CMOS process. Due to high current densities both metal layers should be copper for resistance to elecsronigration. This step is shown in Fig.

332. For clarity, these diagrams may not be to scale, mnd may not represent a -rs section tho any single plane of the nozzle. Fig. 33 1 is a key to representations of various materials in these manufacturing diagrams, and those of SUBSTTUT SLEET (Rule 26) (RaAU) WO 99/0136801 PCTA198/OzS" other cross referenced ink jet configurntons.

2. Etch the CMOS oxide layers down to silicon or aluminum using Mask 1. This mask defines the nozze chamber inlet cross, the edge. of the print heads chips, and the vim %br the contacts flom the second level metal electr~odes to the two halves of the split fixed magnetic pWlae 3. Plasma etch the silicon to a depth of 15 microns, using oxide from step 2 as a mask. This etch does not substantially etch the second level metal. This step is shown in Fig. 333.

4. Deposit a seed layer of cobalt nickel iron alloy. CoNipe is chosen due to a high saturation flux density of 2 Testa, and a low coercivity. [Osaka, Tetsuya et al, A soft magnetic CoNiFe film with high saturation magnetic flux density, Namur 392, 796-798 (1998)].

5.Si n4mcoso eit xoewt ak2 n eeo.Ti akdfnstesltfxdmgei plate, for which the resist acts as an electroplating mold. This step is shown in Fig. 334.

6. Electroplate 3 microns of CoNiFe. This step is shown in Fig. 335.

7. Strip the resist and etch the exposed seed layer. This step is shown in Fig. 336.

S. Deposit 0.5 microns of silicon nitride, which insulates the solenoid front the fixed magnetic plate.

9. Etch the nitride layer using Mask 3. This mask defines the contact vias from each end of the solenoid coil to the two halves of the split fixed magnetic plate, as well as returning the nozzle chamber to a hydrophilic state. This step is shown in Fig. 337.

Deposit an adhesion layer plus a copper seed layer. Copper is used for its low resistivity (which results in higher efficiency) and its high electromigracion resisance, which increases reliability at high current densities.

11. Spin on 13 microns of resist and expose using Mask 4, which defines the solenoid spiral coil, for which the resist acts as an electroplating mold. As the resist is thick and the aspect ratio is high, an X-ray proximity process, such as LlGA.can be used. This step is shown in Fig. 338.

12. Electroplate 12 microns of copper.

13. Snrip the resist and etch the exposed copper seed layer. This step is shown in Fig. 339.

14. Wafer probe. All electrical connections are complete at this point, bond pad are accessible, and the chips are not yet separated.

Deposit 0. 1 microns of silicon nitride, which acts as a corrosion barrier (not shown).

16. Deposit 0.1 microns of PTFE (not shown\ which makes the top surfrce of the fixed magnetic plate and the solenoid hydrophobic, thereby preventing the space between the solenoid and the magnetic piston from filling with ink (if a water based ink is used. In general, these surflices should be made ink-phobic).

17. Etch the PTFE layer using Mask 5. This mask defines the hydrophilic region of the nozzle chamber. The etch returns the nozzle chamber to a hydrophilic state.

ISB. Deposit 1 micron of sacrificial material. This defines the magnetic gap, and the ravel of the magnetic piston.

19. Etch the sacrificial layer using Mask 6. This mask defines die spring posts. This step is shown in Fig.

340.

Deposit a seed layer of CoNiFe.

21. Deposit 12 microns Of resist. As the solenoids will prevent even flow during a spin-on application, the resis should be sprayed on. Expose the resist using Mask 7, whilch defines the walls of the magnetic plunger, plus the spring posts. As the resist is dick and the aspect ratio is high, an X-ray proximity process, such as LIGA, can be SUBSTnr SHEET (Rule 26) (RCYAU) WO 99/03680 PCT/AU98/00548 81 used. This step is shown in Fig. 341.

22. Electroplate 12 micmns of CoNiFe. This step is shown in Pig. 342.

23. Deposit a seed layer of CoNiFe.

24. Spin on 4 microns of resist, expose with Mask 8, and develop. This mask defines the roof of the magnetic plunger, the nozzle, the springs, and the spring posts. The resist fonns an elctroplating mold for these parts.

This step is shown in Fig. 343.

Electroplate 3 microns of CoNiFe. This step is shown in Fig. 344.

26. Strip the resist, sacrificial, and exposed seed layers. This step is shown in Fig. 345.

27. Back-etch through the silicon wafer until the nozzle chamber inlet cross is reached using Mask 9. This etch may be performed using an ASE Advanced Silicon Etcher from Surface Technology Systems. The mask defines the ink inlets which are etched through the wafer. The wafer is also diced by this etch. This step is shown in Fig. 346.

28. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply the appropriate color ink to the ink inlets at the back of the wafer.

29. Connect the print heads to their interconnect systems. For a low profile connection with minimum disruption of airflow, TAB may be used. Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper.

Fill the completed print heads with ink and test them. A filled nozzle is shown in Fig. 347.

IJ USES The presently disclosed inkjet printing technology is potentially suited to a wide range of printing system including: colour and monochrome office printers, short run digital printers, high speed digital printers, offset press supplemental printers, low cost scanning printers high speed pagewidth printers, notebook computers with inbuilt pagewidth printers, portable colour and monochrome printers, colour and monochrome copiers, colour and monochrome facsimile machines, combined printer, facsimile and copying machines, label printers, large format plotters, photograph copiers, printers for digital photographic "minilabs", video printers PhotoCD printers, portable printers for PDAs, wallpaper printers, indoor sign printers, billboard printers, fabric printers, camera printers and fault tolerant commercial printer arrays.

SUBSTITUTE SHEET (Rule 26) (RQOAU) WO 99/03680 PCr/AU9AO0548 82 Ink Jet Technologies The embodiments of the invention use an ink jet prin type device. Of course many differt devices could be used. However presently popular ink jet printing technologies are unlikely to be suitable: The most significant problem with thermal inkier is power consumption. This is approximately 100 times that required for high speed, and stems from the energy-inefficient means of drop ejection. This involves the rapid boiling of water to produce a vapor bubble which expels the ink. Water has a very high heat capacity, and must be superheated in theiral inkjet applications. This leads to a efficiency of around 0.02%, from electricity input to drop momentum (and increased surface ar) out.

The most significant problem with piezoelectric inkjet is size and cost. Piezoelectric crystals have a very small deflection at reasonable drive voltages, and therefore require a large are for each nozzle. Also, each piezoelectric actuator must be connected to its drive circuit on a separate substrate. This is not a significant problem at the current limit ofaround 300 nozzles per print head, but is a major impediment to the fabrication of pagewide print heads with 19,200 nozzles.

Ideally, the inkjet technologies used meet the stringent requirements of in-camera digital color printing and other high quality, high speed, low cost printing applications. To mo the requirements of digital photography, new inkjet technologies have been created. The target features include; low power (less than 10 Watts) high resolution capability (1,600 dpi or more) photographic quality output low manufacturing cost small size (pegewidth times minimum cross section) high speed 2 seconds per page).

All of these features can be met or exceeded by the inkjet systems described below with differing levels of difficulty. 45 different inkjet technologies have been developed by the Assignee to give a wide range of choices for high volume manufacture. These technologies form part of separate applications assigned to the present Assignee as set out in the table below.

The inkjet designs shown here ae suitable for a wide range of digital printing systems, from battery powered one-time use digital cameras, through to desktop and network printers, and through to commercial printing systems For ease of manufacture using standard process equipment, the print head is designed to be a monolithic micron CMOS chip with MEMS post processing. For color photographic applications, the print head is 100 mi long.

with a width which depends upon the inkjet type. The smallest print head designed is U38, which is 0.35 m wide, giving a chip area of 35 square m. The print heads each contain 19,200 nozzles plus data and control circuitry.

Ink is supplied to the back of the print head by injection molded plastic ink channels. The molding requires micron femtures, which can be created using a lithographically micronachined insert in a standard injection molding tool. Ink flows through holes etched through the wafer to the nozzle chambers fabricated on the front surface of the wafe. The print head is connected to the camem circuitry by tape automand bonding.

Cross-Referced Applications SU STrrlJl SHEET (aule 26) (RO/AU) WO 99/03680 PCT/AU98/00548 83 The following table is a guide to cross-referenced patent applicatios filed concurrenly herewith and discussed hereinafter with the reference being utilized in subsequent tables when referring to a particular case: Docket No. Refece Tie IJO 1US U01 Radiant Plunger Ink Jet Printer U02US U02 Electrostatic Ink Jet Printer IJ03US 1J03 Planar Thermoeiastic Bend Actuator ink Jet IJ04US U04 Stacked Electrostatic Ink Jet Printer 105 Reverse Spring Lever Ink Jet Printer 1J06US U06 Paddle Type Ink Jet Printer 1J07US U07 Permanent Magnet Electromagnetic Ink Jet Printer IJOSUS U08 Planar Swing Grill Electromagnetic Ink Jet Printer 1309US U109 Pump Action Refill Ink Jet Printer UtOUS U10 Pulsed Magnetic Field Ink Jet Printer IJ11US U11 Two Plate Reverse Firing Electromagnetic Ink Jet Printer IJ12US [J12 Linear Stepper Actuator Ink Jet Printer U13US J113 Gear Driven Shutter InkJet Printer IJ14US 1314 Tapered Magnetic Pole Electromagnetic InkJet Printer IJISUS 1315 Linear Spring Electromagnetic Grill Ink Jet Printer IJ16US J116 Lorenz Diaphragm Electromagnetic InkJet Printer IJ17US J117 PTFE Surface Shooting Shuttered Oscillating Prsse Ink Jet Printer IJ1 8US IJ18 Buckle Grip Oscillating Pressure Ink JetPrinter [1J 9US U19 Shutter Based Ink Jet Printer U20 Curling Calyx Thennoelastic Ink Jet Printer 21US IJ21 Thermal Actuated Ink Jet Printer U22US U22 Iris Motion Ink Jet Printer 1123US U23 Direct Firing Thermal Bend Actuator Ink Jet Printer

IJ

24US U24 Conductive PTFE Ben Activator Vented Ink Jet Printer IJ25 Magnetostrictive Ink Jet Printer J26US IJ26 Shape Memory Alloy Ink Jet Printer 1J27US U27 Buckle Plate Ink Jet Printer IJ28US 1U28 Thermal Elastic Rotary Impeller Ink Jet Printer U129US9 Themoastic Bend Actuator Ink et Printer 130 Thermoeiastic Bend Actuator Using PTFE and Corrugated Copper Ink Jet Printer

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31US I31 Bend Actuator Direct Ink Supply Ink Jet Printer IJ32US U32 A High Young's Modulus Themoelastic Ink Jet Printer U33US U33 Thermally actuated slotted chamber wall ink jet printer I134US U34 Ink Jet Printer having a thermal actuator coprising an xternal coiled spring 1J35 Trough Container Ink Jet Printer SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/00548 1336US U36 Dual Chnber Single Vetical Actuornmnk et 1J37US IJ37 Dual Nozzle Single Horimntal PFl A axtor Ink Jet 1J38US 138 Dual Nozzle Single Horimntal Actator Ink Jet U139US U39 A single bend actuator cupped paddle inkjet printing device 1U40 A thermally actuated inkjet printer having a series of thermal actuator units U41US IJ41 A themnally actuated ink jet printer including a tapered heater element U42US IJ42 Radial Back-Curling The!noelastic InkJet IJ43US IJ43 Inverted Radial Back-Curling Thermoastic Ink Jet UJ44US 1144 Surce bend actuator vented ink supply inkjet printer 1145 Coil Actuated Magnetic Plate Ink Jet Printer Tables of Drop-on-Demand Inkjets Eleven important characteristics of the fundamental operation of individual inkjet nozzles have been identified. These characteristics are largely orthogonal, and so can be elucidated as an eleven dimensional matrix.

Most of the eleven axes of this matrix include entries developed by the present assignee.

The following tables form the axes of an eleven dimensional table of inkjet types.

Actuator mechanism (18 types) Basic operation mode (7 types) Auxiliary mechanism (8 types) Actuator amplification or modification method (17 types) Actuator motion (19 types) Nozzle refill method (4 types) Method of restricting back-flow through inlet (10 types) Nozzle clearing method (9 types) Nozle plate construction (9 types) Drop ejection direction (5 types) Ink type (7 types) The complete eleven dimensional table represented by these axes contains 36.9 billion possible configurations of inkjet nozzle. While not all ofthe possible combinations result in a viable inkjet technology, many million configurations are viable. It is clearly impractical to elucidate all of the possible configurations. Instead, certain inkjet types have been investigated in detail. These are designated IJ0 to IJ45 above.

Other inkjet configurations can readily be derived from these 45 examples by substituting alternative configurations along one or more of the 11 axes. Most of the U01 to U45 examples can be made into inkjet print heads with characteristics superior to any currntly available inkjet technology.

Where there are prior art examples known to the inventor, one or more of these examples are listed in the examples column of the tables below. The UI01 to 145 series ar also listed in the examples column. In some cases, a printer may be listed more than once in a table, where it shares characteristics with more than one entry.

Suitable applications include: Home printe, Office nework printers, Short run digital printers, Commercial SUBSTImr E SHEET (Rule 26) (RO/AU) wo 99103M WO 9SS6UP/AUS,00548 Print 'ystets Fable I Pacit phm linen WWW Fheu Video pularis, Medical Wm&&n Wid fot Printrs Nowoo PC pinter Fax mudmsi, Indzutral puingt sisem Phiotocopies, Photographic minilaba etc.

The hWmm a so sociated wit the aforentid I I dlmilota matix are set mgt in te bs olowing tables.

SUBSTrrum SHEET (Rule 26) (ROIAUT) AMPOW01111 Actuator mechanism (applied only to selected ink drops) Actutor Description Advantages Disadvantages Examples Mechanism Thermal bubble An electrothermal heater heats the ink to Large force generated High power Canon Bubblejet 1979 above boiling point, transferring significant Simple construction Ink carrier limited to water Endo et al GB patent heat to the aqueous ink. A bubble nucleates No moving parts Low efficiency 2,007,162 and quickly forms, expelling the Ink. Fast operation High temperatures required Xerox heater-in-pit 1990 The efficiency of the process is low, with Small chip area required 4 High mechanical stress Hawkins et al USP typically less than 0.05% of the electrical for actuator Unusual materials required 4,899,181 energy being transformed into kinetic Hewlett-Packard TJ 1982 enery ofhe dop.* Large drive transistors enegy f te dop.Vaught et ml LISP Cavitation causes actuator failure 4,490,728 Kogation reduces bubble formation Large print heads are difficult to fabricate Piezoelectric A piezoelectric crystal such as lead Low power consumption Very large area required for actuator Kyser et al USP 3,946,398 lanthanum zirconate (PZT) is electrically Many Ink types can be Difficult to integrate with electronics Zoltan USP 3,683,212 activated, and either expands, shears, or used High voltage drive transistors required 1973 Stemme USP bends to apply pressure to the ink, ejecting Fast operation Full pagewidth print heads impractical 3,747.120 drops. High efficiency due to actuator size Epson Stylus Requires electrical poling in high field Tektronix strengths during manufacture lJ04 Electra-strIctive 1 An electric field is used to activate electrostriction in relaxor materials such as lead lanthanum zirconate titanate (PLZT) or lead magnesium niobate (PMN).

7 Low power consumption *Many ink types can be used Low thermal expansion Electric field strength required (approx. 3.5 V/pm) can be generated without difficulty Does not require electrical poling Low maximum strain (approx. 0,01%) Large area required for actuator due to low strain Response speed is marginal 10 ps) High voltage drive transistors required Full pagewidth print heads impractical due to actuator size Seiko Epson, Usui et all JP 253401/96 IJ04

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I I I I rerroelectric An electric field is used to induce a phase transition between the antiferroelectric (AFE) and ferroelectric (FE) phase.

Perovskite materials such as tin modified lead lanthanum zirconate titanate (PLZSnT) exhibit large strains of up to 1% associated with the AFE to FE phase transition.

Low power consumption SMany ink types can be used Fast operation I us) Relatively high longitudinal strain High efficiency Electric field strength of around 3 V/pm can be readily provided Difficult to integrate with electronics Unusual materials such as PLZSnT are required Actuators require a large area I *IJ04 6 L_ plates Conductive plates are separated by a compressible or fluid dielectric (usually air). Upon application of a voltage, the plates attract each other and displace ink, causing drop ejection. The conductive plates may be in a comb or honeycomb structure, or stacked to increase the surface area and therefore the force.

Low power consumption Many ink types can be used Fast operation Difficult to operate electrostatic devices in an aqueous environment *The electrostatic actuator will normally need to be separated from the ink Very large area required to achieve high forces High voltage drive transistors may be required Full pagewidth print heads are not competitive due to actuator size I* 02, IJ04 Eleetrastatie pull A strong electric field is applied to the ink, Low current High voltage required 1989 Saito et aI, USP on ink whereupon electrostatic attraction consumption May be damaged by sparks due to air 4,799,068 accelerates the ink towards the print Low temperature breakdown 1989 Miura et al, USP medium. *Required field strength increases as the 4,810,954 drop size decreases Tone-jet High voltage drive transistors required Electrostatic field attracts dust Permanent magnet electromapet An electromagnet directly attracts a permanent magnet, displacing ink and causing drop ejection. Rare earth magnets with a field strength around 1 Tesla can be used. Examples are: Samarium Cobalt (SaCo) and magnetic materials in the neodymium iron boron family (NdFeB, NdDyFeBNb, NdDyFeB, etc) Low power consumption *Many ink types can be used Fast operation High efficiency Easy extension from single nozzles to pagewidth print heads Complex fabrication Permanent magnetic material such as Neodymium Iron Boron (NdFeB) required.

High local currents required 0 Copper metalization should be used for long electromigration lifetime and low resistivity Pigmented inks are usually infeasible Operating temperature limited to the Curie temperature (around 540 K) 1J07, Soft magnetic core electro-magnetic A solenoid induced a magnetic field in a soft magnetic core or yoke fabricated from a ferrous material such as electroplated iron alloys such as CoNiFe CoFe, or NiFe alloys. Typically, the soft magnetic material is in two parts, which are normally held apart by a spring. When the solenoid is actuated, the two parts attract, displacing the ink.

Low power consumption *Many ink types can be used Fast operation High efficiency Easy extension from single nozzles to pagewidth print heads Complex fabrication Materials not usually present in a CMOS fab such as NiPe, CoNIFe, or CoFe are required High local currents required Copper metalization should be used for long electromigration lifetime and low resistivity Electroplating is required High saturation flux density is required (2.0-2.1 T is achievable with CoNiFe 1J01, IJ05, U08, 1J10 112, IJ)4, J15, J17 Magnetic Lorenz force The Lorenz force acting on a current carrying wire in a magnetic field is utilized.

This allows the magnetic field to be supplied externally to the print head, for example with rare earth permanent magnets.

Only the current carrying wire need be fabricated on the print-head, simplifying materials requirements.

Low power consumption Many ink types can be used Fast operation High efficiency Easy extension from single nozzles to pagewidth print heads Force acts as a twisting motion Typically, only a quarter of the solenoid length provides force in a useful direction High local currents required Copper metalization should be used for long electromigration lifetime and low resistivity Pigmented inks are usually infeasible S* 11J06, IJ11, 1113, 1J16 Mapeto-striction The actuator uses the giant Many ink types can be used Force acts as a twisting motion Fischenbeck.

magnetostrictive effect of materials such as Fast operation Unusual materials such as Terfenol-D are USP Terfenol-D (an alloy of terbium, Easy extension from single required 4,032,929 dysprosium and iron developed at the nozzles to pagewidth print High local currents required 1125 Naval Ordnance Laboratory, hence Ter-Fe- heads Copper metalization should be used for long NOL). For best efficiency, the actuator High force is available electromigration lifetime and low should be pre-stressed to approx. 8 MPa. resisivity Pre-stressing may be required Surface tension Ink under positive pressure is held in a Low power consumption Requires supplementary force to effect drop Silverbrook, EP reductiom nozzle by surface tension. The surface Simple construction separation 0771 658 A2 tension of the ink is reduced below the No unusual materials required Requires special ink surfactants and related bubble threshold, causing the ink to egress in fabrication Speed may be limited by surfactant pa ent from the nozzle. High efficiency properties applications Easy extension from single nozzles to pagewidth print heads Viscmity The ink viscosity is locally reduced to Simple construction Requires supplementary force to effect drop Silverbmok, EP reduction select which drops are to be ejected. A No unusual materials required separation 0771 655 A2 viscosity reduction can be achieved in fabrication Requires special ink viscosity properties and related electrothermally with most inks, but special Easy extension from single High speed is difficult to achieve patent inks can be engineered for a 100:1 nozzles to pagewidth print Requires oscillating ink pressure applications viscosity reduction. heas A high temperature difference (typically degrees) is required Acoustic An acoustic wave is generated and Can operate without a nozzle Complex drive circuitry 1993 focussed upon the drop ejection region. plate Complex fabrication Hadimlogu at Low efficiency a, EUP Poor control of drop position 550,192 Poor control of drop volume 1993 Elrod et a[, EUP 572,220 Thermoelastic bend actuator An actuator which relies upon differential thermal expansion upon Joule heating is used, Low power consumption Many ink types can be used Simple planar fabrication Small chip area required for each actuator Fast operation High efficiency CMOS compatible voltages and currents Standard MEMS processes can be used Easy extension from single nozzles to pagewidth print heads Efficient aqueous operation requires a thermal insulator on the hot side Corrosion prevention can be difficult Pigmented inks may be infeasible, as pigment particles may jam the bend actuator S1103, 1J09, J117, IJ19, 1J20, IJ21, IJ22 1323, IJ24, IJ27, IJ28 IJ29. U30, IJ31., IJ32 133, 1J34, U136 U37. 11J38 ,1J39, IJ41 I 1. I.

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HighCTEi thermoelastic actuator A material with a very high coefficient of thermal expansion (CTE) such as polytetrafluoroethylene (PTFE) is used. As high CTE materials are usually nonconductive, a heater fabricated from a conductive material is incorporated. A 50 p m long PTFE bend actuator with polysilicon heater and 15 mW power input can provide 180 pN force and 10 pm deflection. Actuator motions include: 1) Bend 2) Push 3) Buckle 4) Rotate High force can be generated PTFE is a candidate for low dielectric constant insulation in ULSI Very low power consumption Many ink types can be used Simple planar fabrication Small chip area required for each actuator Fast operation High efficiency +CMOS compatible voltages and currents SEasy extension from single nozzles to pagewidth print heads Requires special material PTFE) Requires a PTFE deposition process, which is not yet standard in ULSI fabs *PTFE deposition cannot be followed with high temperature (above 350 tC) processing *Pigmented inks may be infeasible, as pigment particles may jam the bend actuator SIJ09, IJ17, U 18, SIJ21, IJ22, 1J23, 1J24 1127, IJ28, IJ29, SU31, IJ42, IJ43, 1J44 I I I Conductive polymer thermelastlic actuator A polymer with a high coefficient of thermal expansion (such as PTFE) is doped with conducting substances to increase its conductivity to about 3 orders of magnitude below that of copper. The conducting polymer expands when resistively heated.

Examples of conducting dopants include: I) Carbon nanotubes 2) Metal fibers 3) Conductive polymers such as doped polythiophene 4) Carbon granules High force can be generated Very low power consumption Many ink types can be used Simple planar fabrication Small chip area required for each actuator Fast operation High efficiency *CMOS compatible voltages and currents Easy extension from single nozzles to pagewidth print heads Requires special materials development (High CTE conductive polymer) Requires a PTFE deposition process, which is not yet standard in ULSI fabs PTFE deposition cannot be followed with high temperature (above 350 *C) processing Evaporation and CVD deposition techniques cannot be used Pigmented inks may be infeasible, as pigment particles may jam the bend actuator 1 IJ24 4 4 4- 1 Shape memory alloy A shape memory alloy such as TiNi (also known as Nitinol Nickel Titanium alloy developed at the Naval Ordnance Laboratory) is thermally switched between its weak martensitic state and its high stiffness austenic state. The shape of the actuator in its martensitic state is deformed relative to the austenic shape. The shape change causes ejection of a drop.

High force (stresses of MPa) is available hundreds ofI Large strain is available (more than 3%) High corrosion resistance Simple construction Easy extension from single nozzles to pagewidth print heads Fatigue limits maximum number of cycles Low strain is required to extend fatigue resistance Cycle rate limited by heat removal Requires unusual materials (TiNi) *The latent heat of transformation must be provided High current operation Requires pre-stressing to distort the martensitic state I IJ26 1 Low voltage operation I Linear Magnetic Actuator

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Linear magnetic actuators include the Linear Induction Actuator (LIA), Linear Permanent Magnet Synchronous Actuator (LPMSA), Linear Reluctance Synchronous Actuator (LRSA), Linear Switched Reluctance Actuator (LSRA), and the Linear Stepper Actuator (LSA).

Linear Magnetic actuators can be constructed with high thrust, long travel, and high efficiency using planar semiconductor fabrication techniques *Requires unusual semiconductor materials such as soft magnetic alloys CoNiFe Some varieties also require permanent magnetic materials such as Neodymium iron boron (NdFeB) Requires complex multi-phase drive circuitry High current operation I112 Long actuator available travel is Medium force is available Low voltage operation Basic operation mode Openatlaunal mode Description Advantages Disadvantages Examples Actuator directly This is the simplest mode of operation: the Simple operation. Drop repetition rate is usually Thermal inkjet pushes Ink actuator directly supplies sufficient kinetic No external fields required limited to less than 10 KHz. Piezoelectric inkjet energy to expel the drop. The drop must Satellite drops can be avoided if However, this is not 4 1OI, U02, 103,1J04 have a sufficient velocity to overcome the drop velocity is less than 4 m/s fundamental to the method, but 1 06, 07, 1309 1305, [0,10,10 surface tension. Can be efficient, depending upon is related to the refill method t Can be: efficient, depending upon t I11,1 J!4 1j J16 the actuator used normally used *All of the drop kinetic energy 20 2223, 124 1325, IJ26,11327, IJ28 must be provided by the 1325,126,1327, 28 actuator IJ29, IJ30, 1J3 1. IJ32 Satellite drops usually form if 1J33, 1J34, 1135, IJ36 drop velocity is greater than 4.5 IJ37, 1J38, 1139, 1J40 m/s 1J41, 1J42,1143, IJ44 Proximity The drops to be printed are selected by Very simple print head Requires close proximity between Silverbrook 1 EP 0771 some manner thermally induced fabrication can he used the print head and the print 658 A2 and related surface tension reduction of pressurized The drop selection means doe media or transfer roller patent applications ink). Selected drops are separated from the not need to provide the energy May require two print heads ink in the nozzle by contact with the print required to separate the drop printing alternate rows of the medium or a transfer roller. frorn the nozzle image Monolithic color print heads are difficult Electrostatic pull The drops to be printed are selected by Very simple print bead Requires very high electrostatic Silverbrook, EP 0771 on IBnk some manner thermally induced fabrication can be used field 658 A2 and related surface tension reduction of pressurized The drop selection means does Electrostatic field for small nozzle patent applications ink). Selected drops are separated from the not need to provide the energy sizes is above air breakdown Tone-let ink in the nozzle by a strong electric field, required to separate the drop Electrostatic field may attract dust f-rm the nozzle Magnetic pull on The drops to be printed are selected by Very simple print head Requires magnetic ink Silverbrook, EP 0771 ink some manner thermally Induced fabrication can be used ink colors other than black are 658 A2 and related surface tension reduction of pressurized The drop selection means does difficult patent applitations ink). Selected drops are separated from the not need to provide the energy Requires very high magnetic ink in the nozzle by a strong magnetic field required to separate the drop fields acting on the magnetic ink, from the nozzleII

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to a'

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Shutter The actuator moves a shutter to block ink High speed (>50 KHz) operation Moving parts are required *IJ13, 1U17, 1J21 flow to the nozzle. The ink pressure is can be achieved due to reduced Requires ink pressure modulator pulsed at multiple of the drop ejection refill time Friction and wear must be frequency. Drop timing can be very accurate considered The actuator energy can be very Stiction is possible low Shuttered ril The actuator moves a shutter to block ink Actuators with small travel can Moving parts are required *l08, 1J 15, J1, 1J19 flow through a grill to the nozzle. The be used Requires ink pressure modulator shutter movement need only be equal to Actuators with small force can be Friction and wear must be the width of the grill holes. used considered High speed (>50 KHz) operation Stiction is possible can be achieved Pulsed magnetic A pulsed magnetic field atcts an 'ink Extremely low energy operation Requires an external pulsed *IJI0 pull on ink pusher pusher' at the drop ejection frequency. An is possible magnetic field actuator controls a catch, which prevents No heat dissipation problems Requires special materials for the ink pusher from moving when a drop is both the actuator and the ink not to be ejected. pusher Complex construction Auxiiry mechanism (applied to all nozzles) Nome The actuator directly fires the ink drop, and Simplicity of construction Drop ejection energy must be Most inkjets, including there is no external field or other Simplicity of operation supplied by individual nozzle piezoelectric and mechanism required. Small physical size actuator thermal bubble.

UOI- 1.107, IJ09, lI I IJ 12, IJ14, U20, IJ22 1J23-1145 Oscltlag Ink The ink pressure oscillates, providing Oscillating ink pressure can 4 Requires external ink pressure Silverbrook, EP 0771 pressure much of the drop ejection energy. The provide a refill pulse, allowing oscillator 658 A2 and related (Including acoustle actuator selects which drops are to be fired higher operating speed Ink pressure phase and amplitude patent applications utbulmtio) by selectively blocking or enabling The actuators may operate with must be carefully controlled 1108, IJ 13, I 15, IJ17 nozzles. The ink pressure oscillation may much lower energy Acoustic reflections in the ink [Iig, 1119, IJ21 be achieved by vibrating the print head, or Acoustic lenses can be used to chamber must be designed for preferably by an actuator in the ink supply. focus the sound on the nozzles Media proximity The print head is placed in close proximity 4 Low power Precision assembly required Silverbrook, EP 0771 to the print medium. Selected drops High accuracy Paper fibers may cause problems 658 A2 and related protrude from the print head further than Simple print head construction Cannot print on rough substrates patent applications unselected drops, and contact the print medium. The drop soaks into the medium fast enough to cause drop separation.

Transfer roller Drops are printed to a transfer roller 4 High accuracy Bulky Silverbrook, EP 0771 instead of straight to the print medium. A Wide range of print substrates Expensive 658 A2 and related transfer roller can also be used for can be used Complex construction patent applications proximity drop separatlion. Ink can be dried on the transfer Tektronix hot melt roller piezoelectric inkjet Any of the U series Electrostatic An electric field is used to accelerate Low power 4 Field strength required for Silverbrook, EP 0771 selected drops towards the print medium. Simple print head construction separation of small drops is 658 A2 and related near or above air breakdown patent applications Tone-Jet Direct magpetfc A magnetic field is used to accelerate Low power Requires magnetic ink Sllverbrook, EP 0771 id selected drops of magnetic ink towards the Simple print head construction Requires strong magnetic field 658 A2 and related print medium. patent applications Cross magnetic The print head is placed in a constant Does not require magnetic Requires external magnet IJ06, 1J 16 field magnetic field. The Lorenz force in a materials to be integrated in Current densities may be high, current carrying wire is used to move the the print head manufacturing resulting in electromigratlon actuator. process problems Pulsed magnetic A pulsed magnetic field is used to 4 Very low power operation is Complex print head construction Jl0 field cyclically attract a paddle, which pushes on possible Magnetic materials required in the Ink. A small actuator moves a catch, Small print head size print head which selectively prevents the paddle from moving.

Actuator amolification or modification method Actuator Description Advantages Disadvantages Examples amplilcadion None No actuator mechanical amplification is 4 Operational simplicity Many actuator mechanisms have Thermtl Bubble used. The actuator directly drives the drop insufficient travel, or insufficient lnkjet ejection process, force, to efficiently drive the drop v at, IJ02, IJ06, ejection process U07 IJ 16, 1325. 1J26 Differential An actuator material expands more on one Provides greater travel in a 1High stresses are involved Piezoelectric expansion bend side than on the other. The expansion may reduced print head area 4 Care must be taken that the materials 0 1J03, 1.09, IJ17actuator be thermal, piezoelectric, magnetostrictive, The bend actuator converts a high do not delaminate IJ24 or other mechanism, force low travel actuator Residual bend resulting from high 1327, 1.29-1339, mechanism to high travel, temperature or high stress during 1J42, lower force mechanism. formation j43,1 U44 Transient bend A trilayer bend actuator where the two Very good temperature stability High stresses are involved 4 IJ40, 1)41 actuator outside layers arc identical. This cancels 4 High speed, as a new drop can be Care must be taken that the materials bend due to ambient temperature and fired before heat dissipates do not delaminate residual stress. The actuator only responds Cancels residual stress of to transient heating of one side or the other. formation Actuator stack A series of thin actuators are stacked. This Increased travel Increased fabrication complexity Some piezoelectric can be appropriate where actuators require Reduced drive voltage Increased possibility of short circuits ink jets high electric field strength, such as due to pinholes IJ04 electrostatic and piezoelectric actuators.

Multiple actuators Multiple smaller actuators are used Increases the force available from 6 Actuator forces may not add linearly, IJ2, IJ 13, IJ18, simultaneously to move the ink. Each an actuator reducing efficiency actuator need provide only a portion of the Multiple actuators can be 1,22, 1128, U42, force required. positioned to control ink flow IJ43 accurately Unear Spring A linear spring is used to transform a Matches low travel actuator with Requires print head area for the spring 4 motion with small travel and high force higher travel requirements into a longer travel, lower force motion. N Non-contact method of motion transformation Reverse spring The actuator loads a spring. When the Better coupling to the ink Fabrication complexity 1305, IJ I I actuator is turned off, the spring releases. High stress in the spring This can reverse the forceldistance curve of the actuator to make it compatible with the force/time requirements of the drop ejection.

Coiled actuator A bend actuator is coiled to provide greater Increases travel Generally restricted to planar *IJ17, IJ21, U34, travel in a reduced chip area. Reduces chip area implementations due to extreme 1135 Planar implementations we fabrication difficulty in other relatively easy to fabricate. orientations.

IFlexure bead A bend actuator has a small region near the *Simple means of increasing travel Care must be taken not to exceed the [1101 1119, IJ33 actuator fixture point, which flexes much more of a bend actuator elastic l imit in the flexure area readily than the remainder of the actuator. Stress distribution is very uneven The actuator flexing is effectively Difficult to accurately model with convened from an even coiling to an finite element analysis angular bend, resulting In greeter travel of the actuator tip.

Gunr Gears can be used to increase travel at the Low force, low travel actuators Moving parts are required *11J13 expense of duration. Circular gear, rack can be used Several actuator cycles are required and pinion, ratchets, and other gearing a Can be fabricated using standard More complex drive electronics methods can be used. surface MEMS processes Complex construction Friction, friction, and wear are possible Catch The actuator controls a wmall catch. The a Very low actuator energy a Complex construction a 1.110 catch either enables or disables movement a Very small actuator size a Requires external force of an ink pusher that is controlled in a bulk a Unsuitable for pigmented inks Manner.

BDaice plate A buckle plate can be used to change a a Very fast movement achievable a Must stay within elastic limits of the a S. I-irmta et al, "An slow actuator into a fast motion. It can also materials for long device life Ink-jet Head convert t high force, low travel actuator a High stresses involved ,Proc. IEEE into a high travel, medium force motion. a Generally high power requirement MA S Feb.

1996, pp 418- 423.

aitIS, U327 Tapered magnetic A tapered magnetic pole can increase travel Linearizes the magnetic 6 Complex construction 1114 pole at the expense of force. force/distance curve Lever A lever and fuicrum is used to nransfonua a Matches low travel actuator with High stress around the fulcrun 1332, 1J36, 1337 motion with small travel and high force higher travel requirements into a motion with longer travel and lower Fulcrum area has no linear force. The lever can also reverse the movement, and can be used (or direction of travel a fluid seal Rotary Impeller The actuator is connected to a rotary High mechanical advantage Complex construction +1128 impeller. A small angular deflection of the The ratio of force to travel of the Unsuitable for pigmented inks actuator results in a rotation of the impeller actuator can be matched to the vanes, which push the ink against nozzle requirements by stationary vanes and out of the nozzle. varying the number of impeller vanes Acoustic leas A refractive or diffractive zone plate) *No moving parts Large area required 1993 Hadimioglu acoustic lens is used to concentrate sound Only relevant for acoustic ink Jets at fliP waves. 550,192 1993 Elrod at a[, RIP 572,220 Sharp coadnelive A sharp point is used to concentrate an 4 Simple construction *Difficult to fhbricate using standard Tone-jet polat electrostatic field. VLSI processes for a surface ejecting ink-jet 4 Only relevant fir electrostatic ink jets_ Actuator motion Actuator motion Description Advantages Disadvantages Examples Volume expansion The volume of the actuator changes, Simple construction in the case of High energy is typically required to Hewlett-Packard pushing the ink in all directions, thermal inkjet achieve volume expansion. This Thermal Inkjet leads to thermal stress, cavitation, Canon Bubblejet and kogation in thermal ink jet implementations Linear, normal to The actuator moves in a direction normal Efficient coupling to ink drops High fabrication complexity may be IJ01,1102, 1I04, IJ07 chip surface to the print head surface. The nozzle is ejected normal to the surface required to achieve perpendicular J 1, 1114 typically in the line of movement. motion Linear, parallel to The actuator moves parallel to the print Suitable for planar fabrication Fabrication complexity #IJ12, U13, 1115, 133, chip surface head surface. Drop ejection may still be Friction IJ34, IJ35, 1J36 normal to the surface. Stiction Membrane push An actuator with a high force but small The effective area of the actuator Fabrication complexity 1982 Howkins USP area is used to push a stiff membrane that becomes the membrane area Actuator size 4,459,601 is in contact with the ink. Difficulty of integration in a VLSI process Rotary The actuator causes the rotation of some Rotary levers may be used to Device complexity 1J05, 1108, 1J13, 1328 element, such a grill or impeller increase travel May have friction at a pivot point Small chip area requirements Bend The actuator bends when energized. This very small change in Requires the actuator to be made a#1970 Kyser et&S USP may be due to differential thermal dimensions can be converted from at least two distinct layers, 3,946,398 expansion, piezoelectric expansion, to a large motion- or to have a thermal difference 1 973 Stemnme USP magnetostriction, or other form of relative across the actuator 3,747,220 dimensional change. 0 1103, U09, U310, 1319 1123, 1.124, 1325, LU29 13130, 1.13 1, 1133, U334 1335 Swivel The actuator swivels around a central Allows operation where the net inefficient coupling to the ink 1306 pivot Thtis motion is suitable where there linear fbree on the paddle is motion -r opposite force applied toopposite zero sides of the paddle, e.g. Lorenz force. a Small chip area requirements Straightn The actuator is normally bent, and *Can be used with shape memory Requires careful balance of stresses 1326,11J32 straightens when energized. alloys where the austenic phase to ensure that the quiescent bend I is planar is accurateII Double bend The actuator bends in one direction when One actuator can be used to Difficult to make the drops ejected *15J36, 1137, 1)3 8 one element is energized, and bends the power two nozzles. by both bend directions identical, other way when another element is Reduced chip size. a A small efficiency loss compared to energized. s Not sensitive to ambient equivalent single bend actuators.

temperature Shear Energizing the actuator causes a shear *eCan increase the effective travel *#Not readily applicable to other a 1985 Fishbeck USP motion in the actuator material, of piezoelectric actuators actuator mechanisms 4,584,590 Radial coastriction The actuator squeezes an ink reservoir, *Relatively easy to fabricate single High force required 1970 Zoltan USP forcing ink from a constricted nozzle. nozzles from glass tubing as Inefficient 3,683,212 macroscopic structures Difficult to integrate with VLSI processes Conl uncoil A coiled actuator uncoils or coils more Easy to fabricate as a planar *#Difficult to fhtbricate for non-planar *1 17, U21, U134, 1J35 tightly. The motion of the free end of the VLSI process devices actuator ejects the ink. Small area required, therefore Poor out-of-plane stiffnhess low costI BOW The actuator bows (or buckles) in she Can increase the speed of travel Maximum travel is constrained 1316, lU18, 1J27 middle when energized. Mechanically rigid High force required 1mbh-ft Two actuators control a shutter. One *oThe structure is pinned at both e Not readily suitable for inkjets ilt actuator pulls the shutter, and the other ends, so has a high out-of- which directly push the ink pushes it. plane rigidity Curl Inwards A set of actuators curl inwards to reduce Good fluid flow to the region Design complexity 1120, 1142 the volume of ink that they enclose, behind the actuator increases efficiency Curl outwards A set of actuators curl outwards, 4 Relatively simple construction 4 Relatively large chip area *13J43 pressurizing ink in a chamber surrounding the actuators, and expelling ink from a nozzle in the chamber.

Iris Multiple vanes enclose a volume of ink. High efficiency High fabrication complexity 1122 These simultaneously rotate, reducing the Small chip area Not suitable for pigmented inks volume between the vanes.

Acoustic vibration The actuator vibrates at a high frequency. *The actuator can be physically Large area required for efficient 1993 Hadimioglu et distant from the ink operation at useful frequencies al, EUP 550,192 Acoustic coupling and crosstalk 1993 Elrod et al, EUP Complex drive circuitry 572,220 4 Poor control of drop volume and position None In various ink jet designs the actuator does a No moving parts Various other tradeoffs are required Silverbrook, EP 0771 not move. to eliminate moving parts 658 A2 and related patent applications Tone-jet Nozzle refill method Nozzle refill Description Advantages Disadvantages Examples method Surface tension After the actuator is energized, it typically Fabrication simplicity a Low speed a Thermal inkjet returns rapidly to its normal position. This rapid Operational simplicity Surface tension force relatively a Piezoelectric inkJet return sucks in air through the nozzle opening, small compared to actuator JO-J07, J10-IJ14 The ink surface tension at the nozzle then exerts force 16,1120, IJ22-IJ45 a small force restoring the meniscus to a 0 Long refill time usually minimum area. dominates the total repetition rate Shuttered Ink ro the nozzle chamber is provided at a High speed Requires common ink pressure IJOS,IJI13, 135, 1317 oscillating ink pressure that oscillates at twice the drop ejection *#Low actuator energy, as the oscillator .me1, 13 19, 1321 pressure frequency. When a drop is to be ejcted, the actuator need only open or May not be suitable for shutter Is opened for 3 half cycles: drop ejection, close the shutter, instead of pigmented inks actuator return, and refill, ejecting the ink drop Refil actutor After the main actuator has ejected a drop a *#High speed, as the nozzle is *eRequires two independent *1109 second (refill) actuator is energized. The refill actively refilled actuators per nozzle actuator pushes ink into the nozzle chamber. The refill actuator returns slowly, to prevent its return from emptying the chamber again.

Positive In e k i edasih oitv rsue fe Hi1gh refill. rate, therefore a high Surface spill must be prevented Silverbrook, EP 0771 Pressure the ink drop is ejected, the nozzle chamber fills drop repetition rate is Highly hydrophobic print head 658 A2 and related quickly as surface tension and ink pressure both possible surfaces are required patent applications operate to refill the nozzle. Alternative fir *130 1-1307, 13 10-1.114 13 16, 13120, 1322-1J45 Method of restricting back-flow through Inlet Long Inlet channel The ink inlet channel to the nozzle Design simplicity Restricts refill rate Thermal inkjet chamber is made long and relatively Operational simplicity May result in a relatively large chip area Piezoelectric inkjet narrow. relying on viscous drag to reduce Reduces crosstalk Only partially effective 1142,11J43 inlet back-flow.

Pouitive ink The ink is under a positive pressure, so that D~rop selection and Requires a method (such as a nozzle rim 4 Silvertrook, EP 0771 pressure in dhe quiescent state some of the ink drop separation forces can be or effective hydrophobizing, or both) 658 A2 and related already protrudes from the nozzle, reduced to prevent flooding of' the ejection patent applications This reduces the pressure in the nozzle Fast refill time surfac of the print head. *Posil operation of chamber which is required to eject a certain the following: volume of ink. The reduction in chamber a LIOI-IJO?, 1309-1J12 pressure results in a reduction in ink 13 14, 1316, 1.120,1,122, pushed out through the inlet. U23-1.13, 136-1IJ41 #13J44 Raffle One or more baffles are placed in the inlet 4 The refill rate is not as aDesign complexity a HP Thermal Ink Jet ink flow. When the actuator is energized, restricted as the long *May increase fabrication complexity a Tektronix piezoelectric the rapid ink movement creates eddies inlet method. Tektronix hot melt Piezoelectric ink jet which restrict the flow through the inlet. e-Reduces crosstalk print heads).

The slower refill process is unrestricted 1 and does not result in eddies.

Flexible flap In this method recently disclosed by 4Significantly reduces back- a Not applicable to most inkjet *Canon restricts inlet Canon, the expanding actuator (bubble) flow for edge-shooter configurations pushes on a flexible flap that restricts the thermal ink jet devices 4 Increased fabrication complexity inlet. a Inelastic deformation of polymer flap results in creep over extended use Inlet filter A filter is located between the ink inlet and Additional advantage of Restricts refill rate 1J04, U12, I124, IJ27 the nozzle chamber. The filter has a ink filtration May result in complex construction 1329, 1J30 multitude of small holes or slots, restricting Ink filter may be fabricated Ink flow. The filter also removes particles with no additional which may block the nozzle, process steps Small inlet The ink inlet channel to the nozzle Design simplicity Restricts refill rate 102, 1J37, 1144 compared to nozzle chamber has a substantially smaller cross May result in a relatively large chip area section than that of the nozzle, resulting in Only partially effective easier ink egress out of the nozzle than out of the inlet.

Inlet shutter A secondary actuator controls the position Increases speed of the ink- Requires separate refill actuator and IJ09 of a shutter, closing off the ink inlet when jet print head operation drive circuit the main actuator is energized.

The Inlet is located The method avoids the problem of inlet Back-flow problem is Requires careful design to minimize the 1U01, 1103, 1J05,IJ06 behind the Ink- back-flow by arranging the ink-pushing eliminated negative pressure behind the paddle *1107, IJ10, 1 1, IJ14 pushing surface surface of the actuator between the inlet 16, [22, 23,1 and the nozzle.

U28, IJ31, 1J32, IJ33 1J34, IJ35, 1J36, IJ39 *1140, IJ41 Part of the The actuator and a wall of the ink chamber Significant reductions in Small increase in fabrication complexity 1J07, IJ20, 1J26, IJ38 actuator moves to are arranged so that the motion of the back-flow can be shut off the Inlet actuator closes off the inlet, achieved Compact designs possible Nozzle actuator In some configurations of inkjet, there is #Ink back-flow problem is *None related to ink back-flow on Silverbrook, EP 0771 does not result In no expansion or movement of an actuator eliminated actuation 658 A2 and related Ink back-flow which may cause ink back-flow through patent applications the inlet. Valve-jet Tone-jet [J08, .113, 115, 1I17 .113, IJ19, IJ21 Nozzle Clearing Method Nozzle Clearing Description Advantages Disadvantages Examples method Normal nozzle All of the nozzles ae fired periodically, No added complexity on the May not be sufficient to displace Most ink jet systems firlag before the ink has a chance to dry. When print head dried Ink *0 JOi- 1107, U09-V12 not in use the nozzles are sealed (capped) 1114, IJ16, 120, 1J22 against air. 1123- 1J34, lJ36-iJ45 The nozzle firing is usually performed during a special clearing cycle, after first moving the print head to a cleaning station.

Extra power to ink In systems which heat the ink, but do not Can be highly effective if the Requires higher drive voltage *Silverbrook, EP 0771 658 heater boil it under normal situations, nozzle heater is adjacent to the nozzle for clearing A2 and related patent clearing can be achieved by over- May require larger drive applications powering the heater and boiling Ink at the transistors nozzle.

Rapid succession The actuator is fired in rapid succession, Does not require extra drive Effectiveness depends May be used with: ofactuator pulses In some configurations, this may cause circuits on the print head substantially upon the J101-IJ07, 1J09- IJ11 heat build-up at the nozzle which boils the Can be readily controlled and configuration of the inkjet J14, I316, 20, J22 ink, clearing the nozzle. In other initiated by digital logic nozzle I23-I25, I27-1J34 situations, it may cause sufficient IJ36-1345 vibrations to dislodge clogged nozzles.

Extra power to ink Where an actuator is not normally driven A simple solution where Not suitable where there is a May be used with: pushing actuator to the limit of its motion, nozzle clearing applicable hard limit to actuator 1J03, 1J09, I 16, may be assisted by providing an enhanced movement IJ23, 124, IJ25, U27 drive signal to the actuator. 29,30, 131, J32 I39, IJ40, 1J41, IJ42 IJ43, 1J44, Acoustic resonance An ultrasonic wave is applied to the ink A high nozzle clearing capability *High implementation cost if +IJO8, 1J3,lJ 5,]J17 chamber. This wave is of an appropriate can be achieved system does not already IJ18, lI19, IJ21 amplitude and frequency to cause May be implemented at very low include an acoustic actuator sufficient force at the nozzle to clear cost in systems which already blockages. This is easiest to achieve if the include acoustic actuators ultrasonic wave is at a resonant frequency of the ink cavity.

Nozzle clearing A microfabricated plate is pushed against Can clear severely clogged Accurate mechanical alignment Silverbrook, EP 0771 658 plate the nozzles. The plate has a post for every nozzles is required A2 and related patent nozzle. The array of posts Moving parts are required applications *There is risk of damage to the nozzles Accurate fabrication is required Ink pressure pulse The pressure of the ink is temporarily +May be effective where other Requires pressure pump or other May be used with all IJ increased so that ink streams from all of methods cannot be used pressure actuator series ink jets the nozzles. This may be used in 4 Expensive conjunction with actuator energizing. Wasteful of ink Print head wiper A flexible 'blade' is wiped across the print Effective for planar print head Difficult to use if print head Many inkjet systems head surface. The blade is usually surfaces surface is non-planar or very fabricated from a flexible polymer, e.g. Low cost fragile rubber or synthetic elastomer. Requires mechanical parts Blade can wear out in high volume print systems Separate ink A separate heater is provided at the nozzle Can be effective where other 4Fabrication complexity *#Can be used with many Ii boiling heater although the normal drop e--cction nozzle clearing methods series ink jets mechanism does not require it. The cannot be used heaters do not require individual drive *Can be implemented at no circuits, as many nozzles can be cleared additional cost in some inkjet simultaneously, and no imaging is configurations required.

Nozzle piate construction Nozzle plate Description Advantages Disadvantages Examples constructlon Electroformned A nozzle plate is separately fabricated from Fabrication simplicity High temperatures and pressures are Hewlett Packard nickel electroformed nickel, and bonded to the required to bond nozzle plate Thermal Inkjet print head chip. *#Minimum thickness constraints Differential thermal expansion Laser ablated or Individual nozzle holes are ablated by an *No masks required Each hole must be individually Canon Bubblejet drilled polymer intense UV laser in a nozzle plate, which is *Can be quite fast formed 1988 Sercel et al., typically a polymer such as polyimide or Some control over nozzle profile Special equipment required S PIE, Vol. 998 polysulphone is possible 4 Slow where there are many thousands Excimer Beam *Equipment required is relatively of nozzles per print head Applications, pp, low cost May produce thin bunrs at exit holes 768 1993 Watanabe et al., liSP 5,208,604

T_

Silicon micromachined A separate nozzle plate is micromachined from single crystal silicon, and bonded to the print head wafer.

High accuracy is attainable Two part construction High cost Requires precision alignment Nozzles may be clogged by adhesive K. Bean, IEEE Transactions on Electron Devices, Vol. ED-25, No.

1978, pp 1185-1195 Xerox 1990 Hawkins et al., USP 4,899,181 Glass capillaries Fine glass capillaries are drawn from glass No expensive equipment required Very small nozzle sizes are difficult 1970 Zoltan USP tubing. This method has been used for Simple to make single nozzles to form 3,683,212 making individual nozzles, but is difficult Not suited for mass production to use for bulk manufacturing of print heads with thousands of nozzles.

Monolithic, surface micro-machined using VLSI lithographic processes The nozzle plate is deposited as a layer using standard VLSI deposition techniques. Nozzles are etched in the nozzle plate using VLSI lithography and etching.

High accuracy pm) Monolithic Low cost Existing processes can be used Requires sacrificial layer under the nozzle plate to form the nozzle chamber Surface may be fragile to the touch Silverbrook, EP 0771 658 A2 and related patent applications IJ01, 1.102, 1.104, [J11 *J12, .117, 1118, 1122, 1124, IJ27, IJ28 1129, 1130, IJ32 1133, 1134, 1137 *1138, 1139, IJ41 IJ42, IJ43, 4J44 13 1, IJ36, 1140, Monolithic, etched The nozzle plate is a buried etch stop in the Hligh accuracy pn) Requires long etch times 1.103, 1105, [106, through substrate wafer. Nozzle chambers are etched in the Monolithic Requires a support wafer IJ07 front of the wafer, and the wafer is thinned Low cost j08, l309, from the back side. Nozzles are then etched No differential expansion 1J13 in the etch stop layer. U114, IJt5, 1116, 1119 .121, 1123, 1125, IJ26 No nozzle plate Various methods have been tried to No nozzles to become clogged Difficult to control drop position Ricoh 1995 Sekiya eliminate the nozzles entirely, to prevent accurately et al USP nozzle clogging. These include thermal Crosstalk problems 5,412,413 bubble mechanisms and acoustic lens 1993 Hadimioglu et mechanisms al EUP 550,192 1993 Elrod et al EUP 572,220 Trough Each drop ejector has a trough through Reduced manufacturing Drop firing direction is sensitive to 1135 n which a paddle moves. There is no nozzle complexity wicking.

plate. Monolithic Nozzle slit instead The elimination of nozzle holes and No nozzles to become clogged Difficult to control drop position 1989 Saito et at S of Individual replacement by a slit encompassing many accurately USP 4,799,068 nozzles actuator positions reduces nozzle clogging, Crosstalk problems but increases crosstalk due to ink surface Swaves B Drop ejection direction Ejection Description Advantages Disadvantages Examples direction direction Edge Ink flow is along the surface of the chip, Simple construction Nozzles limited to edge Canon Bubblejet ('edge shooter') and ink drops are ejected from the chip No silicon etching required High resolution is difficult 1979 Endo ct al edge. Good heat sinking via substrate Fast color printing requires one print GB patent Mechanically strong head per color 2,007,162 Ease of chip handing Xerox heater-in-pit 1990 Hawkins et al USP 4,899,181 Tone-jet Surface Ink flow is along the surface of the chip, No bulk silicon etching required Maximum ink flow is severely Hewlett-Packard TIJ ('roof shooter') and ink drops are ejected from the chip Silicon can make an effective restricted 1982 Vaught et at surface, normal to the plane of the chip. heat sink USP 4,490,728 Mechanical strength +1102, J11, IJ12, SIJ22 Through chip, Ink flow is through the chip, and ink drops High ink flow Requires bulk silicon etching Silverbrook, EP forward are ejected from the front surface of the Suitable for pagewidth print 0771 658 A2 and ('up shooter') chip. High nozzle packing density related patent therefore low manufacturing applications cost +1J04, 1J17, IJ18, IJ24 UI27-1J45

I

Through chip, reverse ('down shooter') Ink flow is through the chip, and ink drops are ejected from the rear surface of the chip.

High ink flow Suitable for pagewidth print High nozzle packing density therefore low manufacturing cost Requires wafer thinning Requires special handling during manufacture IJ1, 1103, IJ06 1107, IJ08, IJ3, IJ14, 1J19, IJ21, 1J25 IJ26 1J05, 1J09, 1315, IJ23, 2o Lfl

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Through actuator Ink flow is through the actuator, which is Suitable for piezoelectric print Pagewidth print heads require several Epson Stylus not fabricated as part of the same substrate heads thousand connections to drive Tektronix hot melt as the drive transistors. circuits piezoelectric ink Cannot be manufactured in standard jets CMOS fabs Complex assembly required Ink type Ink type Description Advantages Disadvantages Examples Aqueous, dye Water based ink which typically Environmentally friendly Slow drying Most existing contains: water, dye, surfactant, No odor Corrosive inkjets humectant, and biocide. Bleeds on paper All IIJ series ink jets Modem ink dyes have high water- May strikeihrough Silverbrook, EP fastness, light fastness Cockles paper 0771 658 A2 and related patent applications Aqueous, pigment Water based ink which typically *Environmentally friendly Slow drying 1102, J04, 1321, contains: water, pigment, surfactant, No odor Corrosive IJ26 humectant, and biocide. Reduced bleed Pigment may clog nozzles 1J27, Pigments have an advantage in reduced Reduced wicking Pigment may clog actuator Silverbrook, EP bleed, wicking and strikethrough. Reduced strikcthrough mechanisms 0771 658 A2 and *Cock les paper related patent applications Piezoelectric inkjets Thermal ink jets (with significant restrictions) Methyl Ethyl MEK is a highly volatile solvent used for 4 Very fast drying Odorous All 1J series ink jets Ketone (MEK) industrial printing on difficult surfaces Prints on various substrates Flammable such as aluminum cans. such as metals and plastics Alcohol Alcohol based inks can be used where Fast drying Slight odor All IJ series ink jets (ethanol, 2- the printer must operate at temperatures Operates at sub-freezing Flammable butanol, and below the freezing point of water. An temperatures others) example of this is in-camera consumer Reduced paper cockle photographic printing. Low cost Phase change The ink is solid at room temperature, and No drying time- ink instantly High viscosity Tektronix hot melt (hot melt) is melted in the print head before jetting. freezes on the print medium Printed ink typically has a 'waxy' piezoelectric ink Hot melt inks are usually wax based, Almost any print medium can feel jets with a melting point around 80 After be used Printed pages may 'block' 1989 Nowak USP jetting the ink freezes almost instantly No paper cockle occurs Ink temperature may be above the 4,820,346 upon contacting the print medium or a No wicking occurs curie point of permanent magnets All IJ series ink jets transer roller. No bleed occurs Ink heaters consume power No strikethrough occurs Long warm-up time Oil Oil based inks are extensively used in High solubility medium for High viscosity: this is a significant All IJ series ink jets offset printing. They have advantages in some dyes limitation for use in inkjets, improved characteristics on paper lous not cockle paper which usually require a low (especially no wicking or cockle). Oil Does not wick through paper viscosity. Some short chain and soluble dies and pigments are required. multi-branched oils have a sufficiently low viscosity.

Slow drying WO 99/03680 PCT/AU98/00548 122 Ink Jet Printing A large number of new forms of ink jet printers have been developed to facilitate alternative ink jet technologies for the image processing and data distribution system. Various combinations of ink jet devices can be included in printer devices incorporated as part of the present invention. Australian Provisional Patent Applications relating to these ink jets which are specifically incorporated by cross reference include: Australian Provisional Number Filing Date Title P08066 15-Jul-97 Image Creation Method and Apparatus (IJ01) P08072 15-Jul-97 Image Creation Method and Apparatus (IJ02) P08040 15-Jul-97 Image Creation Method and Apparatus (IJ03) P08071 15-Jul-97 Image Creation Method and Apparatus (IJ04) P08047 15-Jul-97 Image Creation Method and Apparatus P08035 15-Jul-97 Image Creation Method and Apparatus (1106) PO8044 15-Jul-97 Image Creation Method and Apparatus (1J07) P08063 15-Jul-97 Image Creation Method and Apparatus (IJOS) P08057 15-Jul-97 Image Creation Method and Apparatus (IJ09) P08056 15-Jul-97 Image Creation Method and Apparatus P08069 15-Jul-97 Image Creation Method and Apparatus (1111) P08049 15-Jul-97 Image Creation Method and Apparatus (J12) P08036 15-Jul-97 Image Creation Method and Apparatus (IJ13) P08048 15-Jul-97 Image Creation Method and Apparatus (IJ14) P08070 15-Jul-97 Image Creation Method and Apparatus (1115) P08067 15-Jul-97 Image Creation Method and Apparatus (I 16) PO8001 15-Jul-97 Image Creation Method and Apparatus (J117) P08038 15-Jul-97 Image Creation Method and Apparatus (IJ18) PO8033 15-Jul-97 Image Creation Method and Apparatus (J 19) PO8002 15-Jul-97 Image Creation Method and Apparatus (1J20) P08068 15-Jul-97 Image Creation Method and Apparatus (1J21)

P

0 8062 15-Jul-97 Image Creation Method and Apparatus (1122) PO8034 15-Jul-97 Image Creation Method and Apparatus (IJ23) P08039 15-Jul-97 Image Creation Method and Apparatus (IJ24) P08041 15-Jul-97 Image Creation Method and Apparatus (1J25) SUBSTITUTE SHEET (Rule 26) (ROIAU) WO 99/03680 PCT/AU98/00548 PO8004 15-Jul-97 Image Creation Method and Apparatus (IJ26) P08037 15-Jul-97 Image Creation Method and Apparatus (IJ27) P08043 I5-Jul-97 Image Creation Method and Apparatus (1J28) P08042 15-Jul-97 Image Creation Method and Apparatus (IJ29) P08064 15-Jul-97 Image Creation Method and Apparatus (1J30) P09389 23-Sep-97 Image Creation Method and Apparatus (1331) P09391 23-Sep-97 Image Creation Method and Apparatus (1J32) PP0888 12-Dec-97 Image Creation Method and Apparatus (IJ33) PP0891 12-Dec-97 Image Creation Method and Apparatus (IJ34) PP0890 12-Dec-97 Image Creation Method and Apparatus PP0873 12-Dec-97 Image Creation Method and Apparatus (IJ36) PP0993 12-Dec-97 Image Creation Method and Apparatus (IJ37) PP0890 12-Dec-97 Image Creation Method and Apparatus (U38) PP1398 19-Jan-98 An Image Creation Method and Apparatus (1J39) PP2592 25-Mar-98 An Image Creation Method and Apparatus (1J40) PP2593 25-Mar-98 Image Creation Method and Apparatus (1141) PP3991 9-Jun-98 Image Creation Method and Apparatus (1J42) PP3987 9-Jun-98 Image Creation Method and Apparatus (IJ43) PP3985 9-Jun-98 Image Creation Method and Apparatus (IJ44) PP3983 9-Jun-98 Image Creation Method and Apparatus Ink Jet Manufacturing Further, the present application may utilize advanced semiconductor fabrication techniques in the construction of large arrays of ink jet printers. Suitable manufacturing techniques are described in the following Australian provisional patent specifications incorporated here by cross-reference: Australian Filing Date Title Provisional Number P07935 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJMO I) P07936 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM02) P07937 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM03) SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/00548 P08061 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM04) P08054 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus P08065 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM06) P08055 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJMO7) P08053 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM08) P08078 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM09) P07933 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus P07950 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM 11) P07949 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM12) P08060 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM 13) P08059 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (lJM14) P08073 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus P08076 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM 16) P08075 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM 7) P08079 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJMI8) P08050 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM 19) P08052 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus P07948 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM21) P07951 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (UM22) P08074 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM23) P07941 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM24) P08077 5-Jul-97 A Method of Manufacture of an Image Creation Apparatus P08058 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM26) P08051 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM27) P08045 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM28) P07952 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM29) P08046 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus P08503 11-Aug-97 A Method of Manufacture of an Image Creation Apparatus P09390 23-Sep-97 A Method of Manufacture of an Image Creation Apparatus (IJM31) SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/00548 P09392 23-Sep-97 A Method of Manufacture of an Image Creation Apparatus (IJM32) PP0889 12-Dec-97 A Method of Manufacture of an Image Creation Apparatus PP0887 12-Dec-97 A Method of Manufacture of an Image Creation Apparatus (IJM36) PP0882 12-Dec-97 A Method of Manufacture of an Image Creation Apparatus (IJM37) PP0874 12-Dec-97 A Method of Manufacture of an Image Creation Apparatus (IJM38) PP1396 19-Jan-98 A Method of Manufacture of an Image Creation Apparatus (IJM39) PP2591 25-Mar-98 A Methodof Manufacture of an Image Creation Apparatus (IJM41) PP3989 9-Jun-98 A Method of Manufacture of an Image Creation Apparatus PP3990 9-Jun-98 A Method of Manufacture of an Image Creation Apparatus (JM42) PP3986 9-Jun-98 A Method of Manufacture of an Image Creation Apparatus (IJM43) PP3984 9-Jun-98 A Method of Manufacture of an Image Creation Apparatus (IJM44) PP3982 9-Jun-98 A Method of Manufacture of an Image Creation Apparatus SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/00548 126 Fluid Supply Further, the present application may utilize an ink delivery system to the ink jet head. Delivery systems relating to the supply of ink to a series of ink jet nozzles are described in the following Australian provisional patent specifications, the disclosure of which are hereby incorporated by cross-reference: Australian Filing Date Title Provisional Number P08003 15-Jul-97 Supply Method and Apparatus (Fl) PO8005 15-Jul-97 Supply Method and Apparatus (F2) P09404 23-Sep-97 A Device and Method (F3) MLIEM Technology Further, the present application may utilize advanced semiconductor microelectromechanical techniques in the construction of large arrays of inkjet printers. Suitable microelectromechanical techniques are described in the following Australian provisional patent specifications incorporated here by cross-reference: Australian Filing Date Title Provisional Number P07943 15-Jul-97 A device (MEMSO1) P08006 15-Jul-97 A device (MEMS02) P08007 15-Jul-97 A device (MEMS03) P08008 15-Jul-97 A device (MEMS04) P08010 15-Jul-97 A device P08011 15-Jul-97 A device (MEMS06) P07947 I5-Jul-97 A device (MEMSO7) P07945 15-Jul-97 A device (MEMS08) P07944 15-Jul-97 A device (MEMS09) P07946 15-Jul-97 A device P09393 23-Sep-97 A Device and Method (MEMS11 PP0875 12-Dec-97 A Device (MEMS12) PP0894 12-Dec-97 A Device and Method (MEMS13) SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/00548 127 IR Technologies Further, the present application may include the utilization of a disposable camera system such as those described in the following Australian provisional patent specifications incorporated here by cross-reference: Australian Filing Date Title Provisional Number PP0895 12-Dec-97 An Image Creation Method and Apparatus (IRO 1) PP0870 12-Dec-97 A Device and Method (IR02) PP0869 12-Dec-97 A Device and Method (IR04) PP0887 12-Dec-97 Image Creation Method and Apparatus PP0885 12-Dec-97 An Image Production System (IR06) PP0884 12-Dec-97 Image Creation Method and Apparatus (IRI 0) PP0886 12-Dec-97 Image Creation Method and Apparatus (IR12) PP0871 12-Dec-97 A Device and Method (IR13) PP0876 12-Dec-97 An Image Processing Method and Apparatus (IR14) PP0877 12-Dec-97 A Device and Method (IR16) PP0878 12-Dec-97 A Device and Method (IR17) PP0879 12-Dec-97 A Device and Method (IRI8) PP0883 12-Dec-97 A Device and Method (IR19) PP0880 12-Dec-97 A Device and Method PP0881 12-Dec-97 A Device and Method (IR21) DotCard Technologies Further, the present application may include the utilization of a data distribution system such as that described in the following Australian provisional patent specifications incorporated here by cross-reference: Australian Filing Date Title Provisional Number PP2370 16-Mar-98 Data Processing Method and Apparatus (Dot 1) PP2371 16-Mar-98 Data Processing Method and Apparatus (Dot02) SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/00548 128 PAGE INTENTIONALLY LEFT BLANK SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/00548 129 Artcam Technologies Further, the present application may include the utilization of camera and data processing techniques such as an Artcam type device as described in the following Australian provisional patent specifications incorporated here by cross-reference: Australian Filing Date Title Provisional Number P07991 15-Jul-97 Image Processing Method and Apparatus (ARTO 1) P08505 I I-Aug-97 Image Processing Method and Apparatus (ARTOla) P07988 15-Jul-97 Image Processing Method and Apparatus (ART02) P07993 15-Jul-97 Image Processing Method and Apparatus (ART03) P08012 15-Jul-97 Image Processing Method and Apparatus (ARTOS) P08017 15-Jul-97 Image Processing Method and Apparatus (ART06) P08014 15-Jul-97 Media Device (ART07) P08025 15-Jul-97 Image Processing Method and Apparatus (ART08) P08032 15-Jul-97 Image Processing Method and Apparatus (ART09) P07999 15-Jul-97 Image Processing Method and Apparatus (ARTIO) P07998 15-Jul-97 Image Processing Method and Apparatus (ARTI1) P08031 15-Jul-97 Image Processing Method and Apparatus (ART12) P08030 15-Jul-97 Media Device (ARTI3) P08498 11-Aug-97 Image Processing Method and Apparatus (ART14) P07997 15-Jul-97 Media Device P07979 15-Jul-97 Media Device (ART16) P08015 15-Jul-97 Media Device (ART17) P07978 15-Jul-97 Media Device (ART 18) P07982 15-Jul-97 Data Processing Method and Apparatus (ART19) P07989 15-Jul-97 Data Processing Method and Apparatus P08019 15-Jul-97 Media Processing Method and Apparatus (ART21) P07980 15-Jul-97 Image Processing Method and Apparatus (ART22) P07942 15-Jul-97 Image Processing Method and Apparatus (ART23) P08018 15-Jul-97 Image Processing Method and Apparatus (ART24) SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/00548 P07938 15-Jul-97 Image Processing Method and Apparatus P08016 15-Jul-97 Image Processing Method and Apparatus (ART26) P08024 15-Jul-97 Image Processing Method and Apparatus (ART27) P07940 15-Jul-97 Data Processing Method and Apparatus (ART28) P07939 15-Jul-97 Data Processing Method and Apparatus (ART29) P08501 11-Aug-97 Image Processing Method and Apparatus P08500 11-Aug-97 Image Processing Method and Apparatus (ART31) P07987 15-Jul-97 Data Processing Method and Apparatus (ART32) P08022 15-Jul-97 Image Processing Method and Apparatus (ART33) P08497 11 -Aug-97 Image Processing Method and Apparatus P08029 15-Jul-97 Sensor Creation Method and Apparatus (ART36) P07985 15-Jul-97 Data Processing Method and Apparatus (ART37) P08020 15-Jul-97 Data Processing Method and Apparatus (ART38) P08023 15-Jul-97 Data Processing Method and Apparatus (ART39) P09395 23-Sep-97 Data Processing Method and Apparatus (ART4) P08021 15-Jul-97 Data Processing Method and Apparatus P08504 1 -Aug-97 Image Processing Method and Apparatus (ART42) P08000 15-Jul-97 Data Processing Method and Apparatus (ART43) P07977 15-Jul-97 Data Processing Method and Apparatus (ART44) P07934 15-Jul-97 Data Processing Method and Apparatus P07990 15-Jul-97 Data Processing Method and Apparatus (ART46) P08499 11-Aug-97 Image Processing Method and Apparatus (ART47) P08502 11-Aug-97 Image Processing Method and Apparatus (ART48) P07981 15-Jul-97 Data Processing Method and Apparatus P07986 15-Jul-97 Data Processing Method and Apparatus (ARTS 1) P07983 15-Jul-97 Data Processing Method and Apparatus (ART52) P08026 15-Jul-97 Image Processing Method and Apparatus (ART53) P08027 15-Jul-97 Image Processing Method and Apparatus (ART54) PO8028 15-Jul-97 Image Processing Method and Apparatus (ART56) SUBSTITUTE SHEET (Rule 26) (RO/AU) WO 99/03680 PCT/AU98/00548 P09394 23-Sep-97 Image Processing Method and Apparatus (ART57) P09396 23-Sep-97 Data Processing Method and Apparatus (ART58) P09397 23-Sep-97 Data Processing Method and Apparatus (ART59) P09398 23-Sep-97 Data Processing Method and Apparatus P09399 23-Sep-97 Data Processing Method and Apparatus (ART61) P09400 23-Sep-97 Data Processing Method and Apparatus (ART62) P09401 23-Sep-97 Data Processing Method and Apparatus (ART63) P09402 23-Sep-97 Data Processing Method and Apparatus (ART64) P09403 23-Sep-97 Data Processing Method and Apparatus P09405 23-Sep-97 Data Processing Method and Apparatus (ART66) PP0959 16-Dec-97 A Data Processing Method and Apparatus (ART68) PP1397 19-Jan-98 A Media Device (ART69) It would be appreciated by a person skilled in the art that numerous variations and/or modifications may be made to the present invention as shown in the specific embodiment without departing from the spirit or scope of the invention as broadly described. The present embodiment is, therefore, to be considered in all respects to be illustrative and not restrictive.

SUBSTITUTE SHEET (Rule 26) (RO/AU)

Claims

1. An ink jet printing nozzle arrangement comprising: a nozzle chamber having an ink ejection slot at one end; a plunger constructed from soft magnetic material positioned between said nozzle chamber and an ink chamber supplying ink to said nozzle chamber; an electric coil located adjacent to the plunger and electrically connected to a nozzle activation signal; wherein said electric coil is located within a cavity defined by a said plunger, said plunger having along one surface a series of slots, said cavity having its dimensions reduced as result of movement of said plunger, said reduction in dimensions resulting in an ink flow through said slots into said nozzle chamber and thereby assisting in the ejection of ink from said ink ejection port.

2. An inkjet printing nozzle as claimed in claim 1 wherein said slots are defined around an inner circumference of said coil and said slots have a substantially constant cross-sectional profile.

3. A nozzle as claimed in Claim 1 wherein said slots are located in a radial manner on one surface of said plunger.

4. An inkjet printing nozzle anangement as claimed in claim 1 further comprising a resilient means for returning said plunger to its quiescent position upon de-activation of the activation signal An inkjet printing nozzle arrangement as claimed in claim 4 wherein said resilient means comprises a torsional spring.

6. An inkjet printing nozzle arrangement as claimed in claim 5 wherein said torsional spring is of an arcuate construction having a circumferential profile substantially the same as that of said plunger.

7. An ink ejection nozzle arangement as claimed in claim 1 further comprising an armature plate constructed from soft magnetic material and wherein said plunger is attracted to said armature plate on the activation of said coil.