WO2006105571A1 - Procede d'hydrofugation d'une tete d'impression par application d'un revetement - Google Patents

Procede d'hydrofugation d'une tete d'impression par application d'un revetement Download PDF

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Publication number
WO2006105571A1
WO2006105571A1 PCT/AU2005/000482 AU2005000482W WO2006105571A1 WO 2006105571 A1 WO2006105571 A1 WO 2006105571A1 AU 2005000482 W AU2005000482 W AU 2005000482W WO 2006105571 A1 WO2006105571 A1 WO 2006105571A1
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WO
WIPO (PCT)
Prior art keywords
printhead
ink
nozzle
hydrophobizing
hydrophobic
Prior art date
Application number
PCT/AU2005/000482
Other languages
English (en)
Inventor
Kia Silverbrook
Original Assignee
Silverbrook Research Pty Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Silverbrook Research Pty Ltd filed Critical Silverbrook Research Pty Ltd
Priority to PCT/AU2005/000482 priority Critical patent/WO2006105571A1/fr
Priority to EP05714351A priority patent/EP1871606A4/fr
Publication of WO2006105571A1 publication Critical patent/WO2006105571A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/14—Structure thereof only for on-demand ink jet heads
    • B41J2/14016—Structure of bubble jet print heads
    • B41J2/14088—Structure of heating means
    • B41J2/14112—Resistive element
    • B41J2/1412—Shape
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/16—Production of nozzles
    • B41J2/1601—Production of bubble jet print heads
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/16—Production of nozzles
    • B41J2/1606—Coating the nozzle area or the ink chamber
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/16—Production of nozzles
    • B41J2/1621—Manufacturing processes
    • B41J2/1626—Manufacturing processes etching
    • B41J2/1628—Manufacturing processes etching dry etching
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/16—Production of nozzles
    • B41J2/1621—Manufacturing processes
    • B41J2/1631—Manufacturing processes photolithography
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/16—Production of nozzles
    • B41J2/1621—Manufacturing processes
    • B41J2/1637—Manufacturing processes molding
    • B41J2/1639—Manufacturing processes molding sacrificial molding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/16—Production of nozzles
    • B41J2/1621—Manufacturing processes
    • B41J2/164—Manufacturing processes thin film formation
    • B41J2/1642—Manufacturing processes thin film formation thin film formation by CVD [chemical vapor deposition]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/16—Production of nozzles
    • B41J2/1621—Manufacturing processes
    • B41J2/164—Manufacturing processes thin film formation
    • B41J2/1645—Manufacturing processes thin film formation thin film formation by spincoating

Definitions

  • the present invention relates to the field of inkjet printers and, discloses an inkjet printing system using printheads manufactured with microelectro-mechanical systems (MEMS) techniques.
  • MEMS microelectro-mechanical systems
  • Ink Jet printers themselves come in many different types.
  • the utilization of a continuous stream of 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 utilized by several manufacturers including Elmjet and Scitex (see also US Patent No. 3373437 by Sweet et al)
  • Piezoelectric ink jet printers are also one form of commonly utilized ink jet printing device. Piezoelectric systems are disclosed by Kyser et. al. in US Patent No. 3946398 (1970) which utilizes a diaphragm mode of operation, by Zolten in US Patent 3683212 (1970) which discloses a squeeze mode of operation of a piezoelectric crystal, Stemme in US Patent No.
  • the ink jet 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 that 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 utilizing the electro-thermal actuator are manufactured by manufacturers such as Canon and Hewlett Packard.
  • a printing technology should have a number of desirable attributes. These include inexpensive construction and 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 consumables.
  • inkjet printheads are normally constructed utilizing micro-electromechanical systems (MEMS) techniques. As such, they tend to rely upon standard integrated circuit construction/fabrication techniques of depositing planar layers on a silicon wafer and etching certain portions of the planar layers. Within silicon circuit fabrication technology, certain techniques are better known than others. For example, the techniques associated with the creation of CMOS circuits are likely to be more readily used than those associated with the creation of exotic circuits including ferroelectrics, galium arsenide etc.
  • MEMS micro-electromechanical systems
  • a desirable characteristic of inkjet printheads would be a hydrophobic nozzle (front) face, preferably in combination with hydrophilic nozzle chambers and ink supply channels. This combination is optimal for ink ejection. Moreover, a hydrophobic front face minimizes the propensity for ink to flood across the front face of the printhead. With a hydrophobic front face, the aqueous inkjet ink is less likely to flood sideways out of the nozzle openings and more likely to form spherical, ejectable microdroplets.
  • hydrophobic front faces and hydrophilic ink chambers are desirable, there is a major problem in fabricating such printheads by MEMS techniques.
  • the final stage of MEMS printhead fabrication is typically ashing of photoresist using an oxygen plasma.
  • any organic, hydrophobic material deposited onto the front face will typically be removed by the ashing process to leave a hydrophilic surface. Accordingly, the deposition of hydrophobic material needs to occur after ashing.
  • a problem with post-ashing deposition of hydrophobic materials is that the hydrophobic material will be deposited inside nozzle chambers as well as on the front face of the printhead.
  • the resultant printhead chip has improved surface characteristics, without comprising the surface characteristics of nozzle chambers. It would further be desirable to provide a printhead fabrication process, in which the resultant printhead chip has a hydrophobic front face in combination with hydrophilic nozzle chambers.
  • a printhead comprising a plurality of nozzles formed on a substrate, each nozzle comprising a nozzle chamber, a nozzle opening defined in a roof of the nozzle chamber and an actuator for ejecting ink through the nozzle opening, wherein at least part of an ink ejection face of the printhead is hydrophobic relative to the inside surfaces of each nozzle chamber.
  • a method of hydrophobizing an ink ejection face of a printhead whilst avoiding hydrophobizing nozzle chambers and/or ink supply channels, the method comprising the steps of:
  • the printhead is an inkjet printhead.
  • the liquid is an inkjet ink.
  • the step of filling the nozzle chambers is priming the printhead with ink.
  • the deposition of the hydrophobizing material is chemical vapour deposition.
  • the printhead face comprises atoms available for covalent bonding with the hydrophobizing material.
  • the atoms are oxygen or nitrogen atoms.
  • the hydrophobizing compound forms covalent bonds with the printhead face.
  • the hydrophobizing material is a silyl compound comprising a hydrophobic group.
  • the hydrophobizing material is a silyl chloride.
  • the hydrophobizing compound is non-polymerizable in the liquid.
  • the hydrophobizing compound is a silyl monochloride.
  • each roof forms at least part of the ink ejection face of the printhead, each roof having a hydrophobic outside surface relative to the inside surfaces of each nozzle chamber.
  • At least part of the ink ejection face has a contact angle of more than 90° and the inside surfaces of the nozzle chambers have a contact angle of less than 90°.
  • At least part of the ink ejection face has a contact angle of more than 110°.
  • the inside surfaces of the nozzle chambers have a contact angle of less than 70°.
  • each nozzle chamber comprises a roof and sidewalls walls formed from a ceramic material.
  • the ceramic material is selected from silicon nitride, silicon oxide or silicon oxynitride.
  • the roof and sidewalls are formed by a chemical vapour deposition process.
  • the ink ejection face is hydrophobic relative to ink supply channels in the printhead, the ink supply channels being configured to supply ink to each nozzle.
  • the ink ejection face comprises a layer of hydrophobic material, and the inside surfaces of each nozzle chamber lacks a layer of hydrophobic material.
  • the hydrophobic material is covalently bonded to at least part of the ink ejection surface.
  • Fig. 1 is a schematic cross-sectional view through an ink chamber of a unit cell of a printhead according to an embodiment using a bubble forming heater element;
  • Fig. 2 is a schematic cross-sectional view through the ink chamber Fig. 1, at another stage of operation;
  • Fig. 3 is a schematic cross-sectional view through the ink chamber Fig. 1, at yet another stage of operation;
  • Fig. 4 is a schematic cross-sectional view through the ink chamber Fig. 1, at yet a further stage of operation;
  • Fig. 5 is a diagrammatic cross-sectional view through a unit cell of a printhead in accordance with an embodiment of the invention showing the collapse of a vapor bubble.
  • Fig. 6 is a schematic, partially cut away, perspective view of a further embodiment of a unit cell of a printhead.
  • Fig. 7 is a schematic, partially cut away, exploded perspective view of the unit cell of Fig. 6.
  • Fig. 8 is a schematic, partially cut away, perspective view of a further embodiment of a unit cell of a printhead.
  • Fig. 9 is a schematic, partially cut away, exploded perspective view of the unit cell of Fig. 8.
  • Fig. 10 is a schematic, partially cut away, perspective view of a further embodiment of a unit cell of a printhead.
  • Fig. 11 is a schematic, partially cut away, exploded perspective view of the unit cell of Fig. 10.
  • Fig. 12 is a schematic, partially cut away, perspective view of a further embodiment of a unit cell of a printhead.
  • Fig. 13 is a schematic, partially cut away, perspective view of a further embodiment of a unit cell of a printhead.
  • Fig. 14 is a schematic, partially cut away, exploded perspective view of the unit cell of Fig. 13.
  • Figs. 15 to 25 are schematic perspective views of the unit cell shown in Figures 13 and 14, at various successive stages in the production process of the printhead.
  • Fig. 26 shows partially cut away schematic perspective views of the unit cell of Figure 25.
  • Fig. 27 shows the unit cell of Fig. 25 primed with a fluid.
  • Fig. 28 shows the unit cell of Fig. 27 with a hydrophobic coating on the nozzle plate
  • the unit cell 1 of a printhead comprises a nozzle plate 2 with nozzles 3 therein, the nozzles having nozzle rims 4, and apertures 5 extending through the nozzle plate.
  • the nozzle plate 2 is plasma etched from a silicon nitride structure which is deposited, by way of chemical vapor deposition (CVD), over a sacrificial material which is subsequently etched.
  • CVD chemical vapor deposition
  • the printhead also includes, with respect to each nozzle 3, side walls 6 on which the nozzle plate is supported, a chamber 7 defined by the walls and the nozzle plate 2, a multi-layer substrate 8 and an inlet passage 9 extending through the multi-layer substrate to the far side (not shown) of the substrate.
  • a looped, elongate heater element 10 is suspended within the chamber 7, so that the element is in the form of a suspended beam.
  • the printhead as shown is a microelectromechanical system (MEMS) structure, which is formed by a lithographic process which is described in more detail below.
  • MEMS microelectromechanical system
  • ink 11 from a reservoir enters the chamber 7 via the inlet passage 9, so that the chamber fills to the level as shown in Figure 1.
  • the heater element 10 is heated for somewhat less than 1 microsecond, so that the heating is in the form of a thermal pulse. It will be appreciated that the heater element 10 is in thermal contact with the ink 11 in the chamber 7 so that when the element is heated, this causes the generation of vapor bubbles 12 in the ink. Accordingly, the ink 11 constitutes a bubble forming liquid.
  • Figure 1 shows the formation of a bubble 12 approximately 1 microsecond after generation of the thermal pulse, that is, when the bubble has just nucleated on the heater elements 10. It will be appreciated that, as the heat is applied in the form of a pulse, all the energy necessary to generate the bubble 12 is to be supplied within that short time.
  • the bubble 12 forms along the length of the element, this bubble appearing, in the cross-sectional view of Figure 1, as four bubble portions, one for each of the element portions shown in cross section.
  • the bubble 12, once generated, causes an increase in pressure within the chamber 7, which in turn causes the ejection of a drop 16 of the ink 11 through the nozzle 3.
  • the rim 4 assists in directing the drop 16 as it is ejected, so as to minimize the chance of drop misdirection.
  • the reason that there is only one nozzle 3 and chamber 7 per inlet passage 9 is so that the pressure wave generated within the chamber, on heating of the element 10 and forming of a bubble 12, does not affect adjacent chambers and their corresponding nozzles.
  • the pressure wave generated within the chamber creates significant stresses in the chamber wall.
  • Forming the chamber from an amorphous ceramic such as silicon nitride, silicon dioxide (glass) or silicon oxynitride gives the chamber walls high strength while avoiding the use of material with a crystal structure. Crystalline defects can act as stress concentration points and therefore potential areas of weakness and ultimately failure.
  • Figures 2 and 3 show the unit cell 1 at two successive later stages of operation of the printhead. It can be seen that the bubble 12 generates further, and hence grows, with the resultant advancement of ink 11 through the nozzle 3.
  • the shape of the bubble 12 as it grows, as shown in Figure 3, is determined by a combination of the inertial dynamics and the surface tension of the ink 11. The surface tension tends to minimize the surface area of the bubble 12 so that, by the time a certain amount of liquid has evaporated, the bubble is essentially disk-shaped.
  • the increase in pressure within the chamber 7 not only pushes ink 11 out through the nozzle 3, but also pushes some ink back through the inlet passage 9.
  • the inlet passage 9 is approximately 200 to 300 microns in length, and is only approximately 16 microns in diameter. Hence there is a substantial viscous drag. As a result, the predominant effect of the pressure rise in the chamber 7 is to force ink out through the nozzle 3 as an ejected drop 16, rather than back through the inlet passage 9.
  • the printhead is shown at a still further successive stage of operation, in which the ink drop 16 that is being ejected is shown during its "necking phase" before the drop breaks off.
  • the bubble 12 has already reached its maximum size and has then begun to collapse towards the point of collapse 17, as reflected in more detail in Figure 21.
  • the collapsing of the bubble 12 towards the point of collapse 17 causes some ink 11 to be drawn from within the nozzle 3 (from the sides 18 of the drop), and some to be drawn from the inlet passage 9, towards the point of collapse. Most of the ink 11 drawn in this manner is drawn from the nozzle 3, forming an annular neck 19 at the base of the drop 16 prior to its breaking off.
  • the drop 16 requires a certain amount of momentum to overcome surface tension forces, in order to break off.
  • the diameter of the neck 19 reduces thereby reducing the amount of total surface tension holding the drop, so that the momentum of the drop as it is ejected out of the nozzle is sufficient to allow the drop to break off.
  • Figures 6 to 29 show further embodiments of unit cells 1 for thermal inkjet printheads, each embodiment having its own particular functional advantages. These advantages will be discussed in detail below, with reference to each individual embodiment. For consistency, the same reference numerals are used in Figures 6 to 29 to indicate corresponding components.
  • the unit cell 1 shown has the chamber 7, ink supply passage 32 and the nozzle rim 4 positioned mid way along the length of the unit cell 1.
  • the drive circuitry 22 is partially on one side of the chamber 7 with the remainder on the opposing side of the chamber.
  • the drive circuitry 22 controls the operation of the heater 14 through vias in the integrated circuit metallisation layers of the interconnect 23.
  • the interconnect 23 has a raised metal layer on its top surface.
  • Passivation layer 24 is formed in top of the interconnect 23 but leaves areas of the raised metal layer exposed. Electrodes 15 of the heater 14 contact the exposed metal areas to supply power to the element 10.
  • the drive circuitry 22 for one unit cell is not on opposing sides of the heater element that it controls. All the drive circuitry 22 for the heater 14 of one unit cell is in a single, undivided area that is offset from the heater. That is, the drive circuitry 22 is partially overlaid by one of the electrodes 15 of the heater 14 that it is controlling, and partially overlaid by one or more of the heater electrodes 15 from adjacent unit cells. In this situation, the center of the drive circuitry 22 is less than 200 microns from the center of the associate nozzle aperture 5. In most Memjet printheads of this type, the offset is less than 100 microns and in many cases less than 50 microns, preferably less than 30 microns.
  • Configuring the nozzle components so that there is significant overlap between the electrodes and the drive circuitry provides a compact design with high nozzle density (nozzles per unit area of the nozzle plate 2). This also improves the efficiency of the printhead by shortening the length of the conductors from the circuitry to the electrodes. The shorter conductors have less resistance and therefore dissipate less energy.
  • the high degree of overlap between the electrodes 15 and the drive circuitry 22 also allows more vias between the heater material and the CMOS metalization layers of the interconnect 23.
  • the passivation layer 24 has an array of vias to establish an electrical connection with the heater 14. More vias lowers the resistance between the heater electrodes 15 and the interconnect layer 23 which reduces power losses.
  • the passivation layer 24 and electrodes 15 may also be provided without vias in order to simplify the fabrication process.
  • the unit cell 1 is the same as that of Figures 6 and 7 apart from the heater element 10.
  • the heater element 10 has a bubble nucleation section 158 with a smaller cross section than the remainder of the element.
  • the bubble nucleation section 158 has a greater resistance and heats to a temperature above the boiling point of the ink before the remainder of the element 10.
  • the gas bubble nucleates at this region and subsequently grows to surround the rest of the element 10.
  • the heater element 10 is configured to accommodate thermal expansion in a specific manner. As heater elements expand, they will deform to relieve the strain. Elements such as that shown in Figures 6 and 7 will bow out of the plane of lamination because its thickness is the thinnest cross sectional dimension and therefore has the least bending resistance. Repeated bending of the element can lead to the formation of cracks, especially at sharp corners, which can ultimately lead to failure.
  • the heater element 10 shown in Figures 8 and 9 is configured so that the thermal expansion is relieved by rotation of the bubble nucleation section 158, and slightly splaying the sections leading to the electrodes 15, in preference to bowing out of the plane of lamination.
  • the geometry of the element is such that miniscule bending within the plane of lamination is sufficient to relieve the strain of thermal expansion, and such bending occurs in preference to bowing. This gives the heater element greater longevity and reliability by minimizing bend regions, which are prone to oxidation and cracking.
  • the heater element 10 used in this unit cell 1 has a serpentine or 'double omega' shape. This configuration keeps the gas bubble centered on the axis of the nozzle.
  • a single omega is a simple geometric shape which is beneficial from a fabrication perspective.
  • the gap 159 between the ends of the heater element means that the heating of the ink in the chamber is slightly asymmetrical. As a result, the gas bubble is slightly skewed to the side opposite the gap 159. This can in turn affect the trajectory of the ejected drop.
  • the double omega shape provides the heater element with the gap 160 to compensate for the gap 159 so that the symmetry and position of the bubble within the chamber is better controlled and the ejected drop trajectory is more reliable.
  • Figure 12 shows a heater element 10 with a single omega shape.
  • the simplicity of this shape has significant advantages during lithographic fabrication. It can be a single current path that is relatively wide and therefore less affected by any inherent inaccuracies in the deposition of the heater material.
  • the inherent inaccuracies of the equipment used to deposit the heater material result in variations in the dimensions of the element. However, these tolerances are fixed values so the resulting variations in the dimensions of a relatively wide component are proportionally less than the variations for a thinner component. It will be appreciated that proportionally large changes of components dimensions will have a greater effect on their intended function.
  • the omega shape directs current flow around the axis of the nozzle aperture 5. This gives good bubble alignment with the aperture for better ejection of drops while ensuring that the bubble collapse point is not on the heater element 10. As discussed above, this avoids problems caused by cavitation.
  • FIG. 13 to 26 another embodiment of the unit cell 1 is shown together with several stages of the etching and deposition fabrication process.
  • the heater element 10 is suspended from opposing sides of the chamber. This allows it to be symmetrical about two planes that intersect along the axis of the nozzle aperture 5. This configuration provides a drop trajectory along the axis of the nozzle aperture 5 while avoiding the cavitation problems discussed above.
  • CMOS processing of a silicon wafer provides a silicon substrate 21 having drive circuitry 22, and an interlayer dielectric ("interconnect") 23.
  • the interconnect 23 comprises four metal layers, which together form a seal ring for the inlet passage 9 to be etched through the interconnect.
  • the top metal layer 26, which forms an upper portion of the seal ring, can be seen in Figure 15.
  • the metal seal ring prevents ink moisture from seeping into the interconnect 23 when the inlet passage 9 is filled with ink.
  • a passivation layer 24 is deposited onto the top metal layer 26 by plasma-enhanced chemical vapour deposition (PECVD). After deposition of the passivation layer 24, it is etched to define a circular recess, which forms parts of the inlet passage 9. At the same as etching the recess, a plurality of vias 50 are also etched, which allow electrical connection through the passivation layer 24 to the top metal layer 26.
  • the etch pattern is defined by a layer of patterned photoresist (not shown), which is removed by O 2 ashing after the etch.
  • a layer of photoresist is spun onto the passivation later 24.
  • the photoresist is exposed and developed to define a circular opening.
  • the dielectric interconnect 23 is etched as far as the silicon substrate 21 using a suitable oxide-etching gas chemistry (e.g. 0 2 /C 4 F 8 ).
  • Etching through the silicon substrate is continued down to about 20 microns to define a front ink hole 52, using a suitable silicon-etching gas chemistry (e.g. 'Bosch etch').
  • a suitable silicon-etching gas chemistry e.g. 'Bosch etch'.
  • the same photoresist mask 51 can be used for both etching steps.
  • Figure 17 shows the unit cell after etching the front ink hole 52 and removal of the photoresist 51.
  • the front ink hole 52 is plugged with photoresist to provide a front plug 53.
  • a layer of photoresist is deposited over the passivation layer 24.
  • This layer of photoresist is exposed and developed to define a first sacrificial scaffold 54 over the front plug 53, and scaffolding tracks 35 around the perimeter of the unit cell.
  • the first sacrificial scaffold 54 is used for subsequent deposition of heater material 38 thereon and is therefore formed with a planar upper surface to avoid any buckling in the heater element (see heater element 10 in Figure 13).
  • the first sacrificial scaffold 54 is UV cured and hardbaked to prevent reflow of the photoresist during subsequent high-temperature deposition onto its upper surface.
  • the first sacrificial scaffold 54 has sloped or angled side faces 55. These angled side faces 55 are formed by adjusting the focusing in the exposure tool (e.g. stepper) when exposing the photoresist.
  • the sloped side faces 55 advantageously allow heater material 38 to be deposited substantially evenly over the first sacrificial scaffold 54.
  • the next stage of fabrication deposits the heater material 38 over the first sacrificial scaffold 54, the passivation layer 24 and the perimeter scaffolding tracks 35.
  • the heater material 38 is typically a monolayer of TiAlN.
  • the heater material 38 may alternatively comprise TiAlN sandwiched between upper and lower passivating materials, such as tantalum or tantalum nitride. Passivating layers on the heater element 10 minimize corrosion of the and improve heater longevity.
  • the heater material 38 is subsequently etched down to the first sacrificial scaffold 54 to define the heater element 10.
  • contact electrodes 15 are defined on either side of the heater element 10.
  • the electrodes 15 are in contact with the top metal layer 26 and so provide electrical connection between the CMOS and the heater element 10.
  • the sloped side faces of the first sacrificial scaffold 54 ensure good electrical connection between the heater element 10 and the electrodes 15, since the heater material is deposited with sufficient thickness around the scaffold 54. Any thin areas of heater material (due to insufficient side face deposition) would increase resistivity and affect heater performance.
  • Adjacent unit cells are electrically insulated from each other by virtue of grooves etched around the perimeter of each unit cell.
  • the grooves are etched at the same time as defining the heater element 10.
  • a second sacrificial scaffold 39 of photoresist is deposited over the heater material.
  • the second sacrificial scaffold 39 is exposed and developed to define sidewalls for the cylindrical nozzle chamber and perimeter sidewalls for each unit cell.
  • the second sacrificial scaffold 39 is also UV cured and hardbaked to prevent any reflow of the photoresist during subsequent high-temperature deposition of the silicon nitride roof material.
  • silicon nitride is deposited onto the second sacrificial scaffold 39 by plasma enhanced chemical vapour deposition.
  • the silicon nitride forms a roof 44 over each unit cell, which is the nozzle plate 2 for a row of nozzles.
  • Chamber sidewalls 6 and unit cell sidewalls 56 are also formed by deposition of silicon nitride.
  • the nozzle rim 4 is etched partially through the roof 44, by placing a suitably patterned photoresist mask over the roof, etching for a controlled period of time and removing the photoresist by ashing.
  • the nozzle aperture 5 is etched through the roof 24 down to the second sacrificial scaffold 39. Again, the etch is performed by placing a suitably patterned photoresist mask over the roof, etching down to the scaffold 39 and removing the photoresist mask.
  • the first and second sacrificial scaffolds of photoresist, together with the front plug 53 are ashed off using an O 2 plasma. Accordingly, fluid connection is made from the ink supply channel 32 through to the nozzle aperture 5.
  • a portion of photoresist, on either side of the nozzle chamber sidewalls 6, remains encapsulated by the roof 44, the unit cell sidewalls 56 and the chamber sidewalls 6.
  • This portion of photoresist is sealed from the O 2 ashing plasma and, therefore, remains intact after fabrication of the printhead.
  • This encapsulated photoresist advantageously provides additional robustness for the printhead by supporting the nozzle plate 2.
  • the printhead has a robust nozzle plate spanning continuously over rows of nozzles, and being supported by solid blocks of hardened photoresist, in addition to support walls.
  • a hydrophobic material may be deposited onto the roof 44 at this stage by, for example, chemical vapour deposition.
  • the whole of the front face of the printhead may be coated with hydrophobic material.
  • predetermined regions of the roof 44 e.g. regions surrounding each nozzle aperture 5
  • die final stage of printhead fabrication involves ashing off the photoresist, which occupies the nozzle chambers. Since hydrophobic coating materials are generally organic in nature, the ashing process will remove the hydrophobic coating on the roof 44 as well as the photoresist 39 in the nozzle chambers. Hence, a hydrophobic coating step at this stage would ultimately have no effect on the hydrophobicity of the roof 44.
  • a hydrophobic material may be deposited onto the roof 44 at this stage by, for example, chemical vapour deposition.
  • the CVD process will deposit the hydrophobic material both onto the roof 44, onto nozzle chamber sidewalls, onto the heater element 10 and inside ink supply channels 32.
  • a hydrophobic coating inside the nozzle chambers and ink supply channels would be highly undesirable in terms of creating a positive ink pressure biased towards the nozzle chambers.
  • a hydrophobic coating on the heater element 10 would be equally undesirable in terms of kogation during printing.
  • FIG. 27 there is shown a process for depositing a hydrophobic material onto the roof 44, which eliminates the aforementioned selectivity problems.
  • die printhead is primed with a liquid, which fills the ink supply channels 32 and nozzle chamber up to the rim 4.
  • the liquid is preferably ink so that the hydrophobic deposition step can be incorporated into the overall printer manufacturing process.
  • the front face of the printhead, including the roof 44 is coated with a hydrophobic material 61 by chemical vapour deposition (see Figure 28).
  • the hydrophobic material 61 cannot be deposited inside the nozzle chamber, because the ink 60 effectively seals the nozzle aperture 5 from the vapour.
  • the ink 60 protects the nozzle chamber and allows selective deposition of the hydrophobic material 61 onto the roof 44.
  • the final printhead has a hydrophobic front face in combination with hydrophilic nozzle chambers and ink supply channels.
  • the choice of hydrophobic material is not critical. Any hydrophobic compound, which can adhere to the roof 44 by either covalent bonding, ionic bonding, chemisorption or adsorption may be used. The choice of hydrophobic material will depend on the material forming the roof 44 and also the liquid used to prime the nozzles.
  • the roof 44 is formed from silicon nitride, silicon oxide or silicon oxynitride.
  • the hydrophobic material is typically a compound, which can form covalent bonds with the oxygen or nitrogen atoms exposed on the surface of the roof.
  • suitable compounds are silyl chlorides (including monochlorides, dichlorides, trichlorides) having at least one hydrophobic group.
  • the hydrophobic group is typically a Ci. 2 oalkyl group, optionally substituted with a plurality of fluorine atoms.
  • the hydrophobic group may be perfluorinated, partially fluorinated or non-fluorinated.
  • hydrophobic compounds include: trimethylsilyl chloride, dimethylsilyl dichloride, methylsilyl trichloride, triethylsilyl chloride, octyldimethylsilyl chloride, perfluorooctyldimethylsilyl chloride, perfluorooctylsilyl trichloride, perfluorooctylchlorosilane etc.
  • the nozzles are primed with an inkjet ink.
  • the hydrophobic material is typically a compound, which does not polymerise in aqueous solution and form a skin across the nozzle aperture 5.
  • non-polymerizable hydrophobic compounds include: trimethylsilyl chloride, triethylsilyl chloride, perfluorooctyldimethylsilyl chloride, perfluorooctylchlorosilane etc.
  • silyl chlorides have been exemplified as hydrophobizing compounds hereinabove, it will be appreciated that the present invention may be used in conjunction with any hydrophobizing compound, which can be deposited by CVD or another suitable deposition process.
  • the invention has been described above with reference to printheads using bubble forming heater elements. However, it is potentially suited to a wide range of printing system including: color 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 color and monochrome printers, color and monochrome copiers, color and monochrome facsimile machines, combined printer, facsimile and copying machines, label printers, large format plotters, photograph copiers, printers for digital photographic "minilabs", video printers, PHOTO CD (PHOTO CD is a registered trade mark of the Eastman Kodak Company) printers, portable printers for PDAs, wallpaper printers, indoor sign printers, billboard printers, fabric printers, camera printers and fault tolerant commercial printer arrays.
  • PHOTO CD PHOTO CD is a registered trade mark of the Eastman Kodak Company
  • inventions of the invention use an ink jet printer type device. Of course many different devices could be used.
  • thermal ink jet The most significant problem with thermal ink jet 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 thermal ink jet applications. In conventional thermal inkjet printheads, this leads to an efficiency of around 0.02%, from electricity input to drop momentum (and increased surface area) out.
  • piezoelectric inkjet 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 area 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 of around 300 nozzles per printhead, but is a major impediment to the fabrication of pagewidth printheads with 19,200 nozzles.
  • the ink jet technologies used meet the stringent requirements of in-camera digital color printing and other high quality, high speed, low cost printing applications.
  • new ink jet 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 (pagewidth times minimum cross section) high speed ( ⁇ 2 seconds per page).
  • inkjet designs shown here are 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.
  • the printhead is designed to be a monolithic 0.5 micron CMOS chip with MEMS post processing.
  • the printhead is 100 mm long, with a width which depends upon the ink jet type.
  • the smallest printhead designed is IJ38, which is 0.35 mm wide, giving a chip area of 35 square nun.
  • the printheads each contain 19,200 nozzles plus data and control circuitry.
  • Ink is supplied to the back of the printhead by injection molded plastic ink channels.
  • the molding requires 50 micron features, which can be created using a lithographically micromachined 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 wafer.
  • the printhead is connected to the camera circuitry by tape automated bonding.
  • 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) Nozzle plate construction (9 types) Drop ejection direction (5 types) Ink type (7 types)
  • ink jet configurations can readily be derived from these forty-five examples by substituting alternative configurations along one or more of the 11 axes.
  • Most of the IJOl to IJ45 examples can be made into ink jet printheads with characteristics superior to any currently available ink jet technology.
  • print technology may be listed more than once in a table, where it shares characteristics with more than one entry. Suitable applications for the ink jet technologies include: Home printers, Office network printers, Short run digital printers, Commercial print systems, Fabric printers, Pocket printers, Internet WWW printers, Video printers, Medical imaging, Wide format printers, Notebook PC printers, Fax machines, Industrial printing systems, Photocopiers, Photographic minilabs etc.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Particle Formation And Scattering Control In Inkjet Printers (AREA)

Abstract

L'invention concerne un procédé destiné à hydrofuger la face d'éjection de l'encre d'une tête d'impression, ledit procédé évitant l'hydrofugation des chambres de buses et/ou des canaux d'amenée d'encre (32). Le procédé comprend les étapes consistant à (a) remplir de liquide les chambres de buses sur la tête d'impression et (b) déposer un matériau hydrofugeant (61) sur la face d'éjection de l'encre (44) de ladite tête. Ce procédé offre l'avantage d'être sélectif lors du dépôt de matériau hydrofugeant par dépôt chimique en phase vapeur.
PCT/AU2005/000482 2005-04-04 2005-04-04 Procede d'hydrofugation d'une tete d'impression par application d'un revetement WO2006105571A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/AU2005/000482 WO2006105571A1 (fr) 2005-04-04 2005-04-04 Procede d'hydrofugation d'une tete d'impression par application d'un revetement
EP05714351A EP1871606A4 (fr) 2005-04-04 2005-04-04 Procede d'hydrofugation d'une tete d'impression par application d'un revetement

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/AU2005/000482 WO2006105571A1 (fr) 2005-04-04 2005-04-04 Procede d'hydrofugation d'une tete d'impression par application d'un revetement

Publications (1)

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WO2006105571A1 true WO2006105571A1 (fr) 2006-10-12

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EP (1) EP1871606A4 (fr)
WO (1) WO2006105571A1 (fr)

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EP0882593A1 (fr) * 1997-06-05 1998-12-09 Xerox Corporation Procédé de fabrication d'une face frontale hydrophobe/hydrophile d'une tête d'impression à jet d'encre
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EP0882593A1 (fr) * 1997-06-05 1998-12-09 Xerox Corporation Procédé de fabrication d'une face frontale hydrophobe/hydrophile d'une tête d'impression à jet d'encre
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101610909B (zh) * 2007-03-12 2010-12-29 西尔弗布鲁克研究股份有限公司 制造具有疏水喷墨面的打印头的方法以及打印头

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EP1871606A1 (fr) 2008-01-02

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