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
  • B41J2/14129—Layer structure
• • 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
  • B41J2/1603—Production of bubble jet print heads of the front shooter type
• • 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
  • B41J2/1626—Manufacturing processes etching
  • B41J2/1629—Manufacturing processes etching wet 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
  • B41J2/1632—Manufacturing processes machining
• • 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
  • B41J2/1632—Manufacturing processes machining
  • B41J2/1634—Manufacturing processes machining laser machining

Definitions

• the present invention relates to fluid ejection devices, and more particularly to a plurality of barrier layers in a fluid ejection device.
• thermal actuated printheads tend to use resistive elements or the like to achieve ink expulsion, while mechanically actuated printheads tend to use piezoelectric transducers or the like.
• a representative thermal inkjet printhead has a plurality of thin film resistors provided on a semiconductor substrate.
• a barrier layer is deposited over thin film layers on the substrate. The barrier layer defines firing chambers about each of the resistors, an orifice corresponding to each resistor, and an entrance or fluid channel to each firing chamber.
• ink is provided through a slot in the substrate and flows through the fluid channel defined by the nozzle layer to the firing chamber.
• Actuation of a heater resistor by a "fire signal" causes ink in the corresponding firing chamber to be heated and expelled through the corresponding orifice.
• a "fire signal" causes ink in the corresponding firing chamber to be heated and expelled through the corresponding orifice.
• Continued adhesion between the nozzle layer and the thin film layers is desired.
• printhead substrate dies especially those that are larger-sized or that have high aspect ratios, unwanted warpage, and thus nozzle layer delamination, may occur due to mechanical or thermal stresses.
• the nozzle layer has a different coefficient of thermal expansion than that of the semiconductor substrate. The thermal stresses may lead to delamination of the nozzle layer, or other thin film layers, ultimately leading to ink leakage and/or electrical shorts.
• the nozzle layer can undergo stresses due to nozzle layer shrinkage after curing of the layer, structural adhesive shrinkage during assembly of the nozzle layer, handling of the device, and thermal cycling of the fluid ejection device.
• a fluid ejection device comprises a substrate having a first surface; a fluid ejector formed over the first surface; and a cover layer defining a firing chamber formed about the fluid ejector, and defining a nozzle over the firing chamber.
• the cover layer is formed by at least two SU8 layers.
• Fig. 1 illustrates a perspective view of an embodiment of a fluid ejection cartridge of the present invention.
• Fig. 2 illustrates a cross-sectional view of an embodiment of a fluid ejection device taken through section 2-2 of Fig. 1.
• Fig. 3 is a perspective view of an embodiment of a barrier island and a corresponding firing chamber.
• Figs. 4A-4D are cross-sectional views of an embodiment of a process for the present invention.
• Fig. 5 is the flow chart for the views in Figs. 4A-4D.
• Fig. 6 is a cross-sectional view of an embodiment of the present invention, with a layer in addition to that shown in Fig. 4D.
• Figs. 1 illustrates a perspective view of an embodiment of a fluid ejection cartridge of the present invention.
• Fig. 2 illustrates a cross-sectional view of an embodiment of a fluid ejection device taken through section 2-2 of Fig. 1.
• Fig. 3 is a perspective view
• FIG. 7A-7H are cross-sectional views of an embodiment of a process for the present invention.
• Fig. 8 is the flow chart for the views in Figs. 7A-7H.
• Fig. 9 is a cross-sectional view of an embodiment of the present invention, with a layer in addition to that shown in Fig. 7H.
• Figs. 10A-10F are cross-sectional views of an embodiment of a process for the present invention.
• Fig. 11 is the flow chart for the views in Figs. 10A-10F.
• Fig. 12 is a cross-sectional view of an embodiment of the present invention, with a layer in addition to that shown in Fig. 1 OF.
• Fig. 1 is a perspective view of an embodiment of a cartridge 101 having a fluid ejection device 103, such as a printhead.
• the cartridge houses a fluid supply, such as ink. Visible at the outer surface of the printhead are a plurality of orifices or nozzles 105 through which fluid is selectively expelled. In one embodiment, the fluid is expelled upon commands of a printer (not shown) communicated to the printhead through electrical connections 107.
• the embodiment of Fig. 2 illustrates a cross-sectional view of the printhead 103 of Fig. 1 where a slot 110 is formed through a substrate 115.
• the substrate 115 is silicon.
• the substrate is one of the following: single crystalline silicon, polycrystalline silicon, gallium arsenide, glass, silica, ceramics, or a semiconducting material.
• the various materials listed as possible substrate materials are not necessarily interchangeable and are selected depending upon the application for which they are to be used. In the embodiment of Fig.
• a thin film stack 116 (such as an active layer, an electrically conductive layer, and a layer with micro-electronics) is formed or deposited on a front or first side (or surface) of the substrate 115.
• the thin film stack 116 includes a capping layer 117 formed over a first surface of the substrate.
• Capping layer 117 may be formed of a variety of different materials such as field oxide, silicon dioxide, aluminum oxide, silicon carbide, silicon nitride, and glass (PSG).
• a layer 119 is deposited or grown over the capping layer 117.
• the layer 119 is one of titanium nitride, titanium tungsten, titanium, a titanium alloy, a metal nitride, tantalum aluminum, and aluminum silicon.
• a conductive layer 121 is formed by depositing conductive material over the layer 119.
• the conductive material is formed of at least one of a variety of different materials including aluminum, aluminum with about V2 % copper, copper, gold, and aluminum with V2V0 silicon, and may be deposited by any method, such as sputtering and evaporation.
• the conductive layer 121 is patterned and etched to form conductive traces. After forming the conductor traces, a resistive material 125 is deposited over the etched conductive material 121.
• the resistive material is etched to form an ejection element 201, such as a fluid ejector, a resistor, a heating element, and a bubble generator.
• ejection element 201 such as a fluid ejector, a resistor, a heating element, and a bubble generator.
• suitable resistive materials are known to those of skill in the art including tantalum aluminum, nickel chromium, tungsten silicon nitride, and titanium nitride, which may optionally be doped with suitable impurities such as oxygen, nitrogen, and carbon, to adjust the resistivity of the material.
• the thin film stack 116 further includes an insulating passivation layer 127 formed over the resistive material. Passivation layer 127 may be formed of any suitable material such as silicon dioxide, aluminum oxide, silicon carbide, silicon nitride, and glass.
• a cavitation layer 129 is added over the passivation layer 127.
• the cavitation layer is tantalum.
• a cover layer, such as a barrier layer, 124 is deposited over the thin film stack 116, in particular, the cavitation layer 129.
• the cover layer 124 is a layer comprised of a fast cross-linking polymer such as photoimagable epoxy (such as SU8 developed by IBM), photoimagable polymer or photosensitive silicone dielectrics, such as SINR-3010 manufactured by ShinEtsuTM, or an epoxy siloxane, such as PCX30 manufactured by Polyset Co. Inc. in Mechanicsville, NY.
• the cover layer 124 is made of a blend of organic polymers which is substantially inert to the corrosive action of ink.
• Polymers suitable for this purpose include products sold under the trademarks VACREL and RISTON by E. I. DuPont de Nemours and Co. of Wilmington, Del.
• VACREL trademarks of Chemical Chemical Company
• RISTON trademarks of E. I. DuPont de Nemours and Co. of Wilmington, Del.
• An example of the physical arrangement of the cover layer, and thin film substructure is illustrated at page 44 of the Hewlett-Packard Journal of February 1994. Further examples of printheads are set forth in commonly assigned U.S. Pat. No. 4,719,477, U.S. Pat. No. 5,317,346, and U.S. Pat. No. 6,162,589.
• Embodiments of the present invention include having any number and type of layers formed or deposited over the substrate, depending upon the application.
• the cover layer 124 defines a firing chamber 202 where fluid is heated by the corresponding ejection element 201 and defines the nozzle orifice 105 through which the heated fluid is ejected. Fluid flows through the slot 110 and into the firing chamber 202 via channels 203 formed with the cover layer 124. Propagation of a current or a "fire signal" through the resistor causes fluid in the corresponding firing chamber to be heated and expelled through the corresponding nozzle 105.
• the cover layer 124 includes two layers 205, 207.
• the first layer 205 such as a primer layer and a bottom layer, is formed over layer 129, and the second layer 207 (such as a top coat layer, a chamber layer, and a nozzle layer) is formed over layer 205.
• the first layer 205 at least partially defines the firing chamber 202
• the second layer 207 defines a ceiling of the fluid channel 203, the remainder of the firing chamber and walls, as well as the nozzle 105.
• the first layer 205 defines the firing chamber walls
• the second layer 207 defines the nozzle.
• layers 205 and 207 are formed of different materials.
• layers 205 and 207 are formed of the same material.
• the layers 205 and 207 are about the same thickness, or layer 207 is thicker than layer 205, or layer 205 is thicker than layer 207. In this embodiment, layer 205 is thinner than layer 207. In one embodiment, layer 205 has a thickness of about 2 to 15 microns, preferably 2 to 6 microns, preferably 2 microns. In one embodiment, layer 207 has a thickness of about 20 to 60 microns, preferably 30 microns. In one embodiment, the thickness of the primer layer is less than about 50% of the entire thickness of the layer 124. In one embodiment, the primer layer 205 is a low viscosity SU8 material that is cured at 210°C.
• the material for the primer layer 205 is chosen for resistance to inlc and for adhesion to the thin film stack 116 and the nozzle or chamber layer.
• the primer layer 205 is more flexible than the other layers of the cover layer 124.
• the primer layer 205 has more ink resistance than the other layers of the cover layer 124.
• the primer layer 205 is formed of NANO TM SU8 Flex CP which is a lower modulus SU8 formation.
• the primer layer 205 is a flexibilized epoxy.
• the primer layer 205 is a polyimide — polyamide layer.
• the primer layer 205 is SU8 with alternative Photo-Acid-Generator (PAG) loading that makes the material photosensitive.
• the primer layer 205 is cured to a higher temperature than that of other layers in the cover layer 124. With this higher temperature may come more resistance to ink, and more stress. However, the thickness of the layer 205 remains relatively thin to reduce undesirable cracking.
• the layer 207 has high resolution photolithographic characteristics. In one embodiment, the layer 207 is cured at 170°C. In the embodiment shown in Figs. 4A-4D, the process of forming the two layer (205, 207) barrier layer 124 is illustrated. The embodiment of Fig. 5 shows the flow chart corresponding to the process illustrated in Figs.
• the primer layer 205 is coated in step 500, and exposed in step 510.
• a nozzle layer material 207a coats the primer layer 205 in step 520 and as shown in Fig. 4A.
• the nozzle layer 207 is exposed in two masks as shown in Figs. 4B and 4C.
• the remaining unexposed nozzle layer material 207a is developed and thereby removed.
• the nozzle layer forms the firing chamber 202 and nozzle 105.
• an additional top coat 209 is formed over the nozzle layer 207.
• the top coat 209 is photodefinable.
• the top coat 209 is formed of SU8.
• the top coat is non-wetting.
• the top coat 209 is a planarizing layer to planarize the often rough topography of the nozzle layer.
• the top coat 209 is a mask drawn to produce countersunk bores to reduce puddling.
• the top coat 209 has low surface energy.
• the top coat 209 is a siloxane based material.
• the top coat 209 is a fluoropolymer based material.
• the thickness of layer 209 is in the range of about Vi to 5 microns, preferably 1.1 microns. In the embodiment shown in Figs.
• FIG. 7A-7H the process of forming the three layer (205, 206, 208) barrier layer 124 is illustrated.
• the embodiment of Fig. 8 shows the flow chart corresponding to the process illustrated in Figs. 7A to 7H.
• step 800 the thin films 116 forming the fluid ejectors are deposited over the substrate.
• step 810 the primer layer 205 is spun onto the thin film layers 116 and patterned.
• step 820 and as illustrated in Fig. 7A, a material 206a that forms the chamber layer is spun on.
• the material 206a is patterned or exposed to form the chamber layer 206.
• the material 206a is developed and thereby removed.
• step 830 and illustrated in Fig. 7D, fill material 300, such as resist, coats the chamber layer 206.
• the fill material 300 is planarized, by methods such as CMP, patterning and developing of material.
• step 850 and as illustrated in Fig. 7F, the chamber layer 206 and planarized material 300 is coated with a material 208a that forms the nozzle layer.
• the nozzle layer 208 is exposed.
• step 850 the material 208a is developed.
• step 860 and as illustrated in Fig. 7H, the fill material (such as resist) is removed.
• the primer layer of Fig. 7H in this embodiment, has a thickness in the range of about 2 to 15 microns, more particularly 2 to 6 microns, even more particularly 2 microns.
• the chamber layer 206 and the nozzle layer 208 each have a thickness in the range of about 10 to 30 microns.
• at least one of the layers 206 and 208 have a thickness in the range of about 15 to 20 microns.
• at least one of the layers 206 and 208 have a thickness of 15 or 20 microns.
• the nozzle layer 208 is formed of a material similar to that of layer 207 described above.
• the chamber layer 206 is formed of a material similar to that of layer 207 described above.
• the chamber layer 206 is formed of an SU8 with a photobleachable dye for z-contrast.
• z-contrast refers to the direction perpendicular to the substantially planar substrate.
• z-contrast refers to placing an absorbing material in the formulation to extinguish the light intensity from top to bottom.
• the 'contrast' refers to the sharpness of the transition between a photo acid concentration that causes the SU8 material to resist the developer and a concentration that is dissolved by the developer. In one embodiment, the sharper this transition; the more square the feature.
• this photobleachable dye bleaches and becomes transparent at a sufficient dosage of electromagnetic energy.
• an additional top coat 209 is formed over the nozzle layer 208.
• the top coat 209 is similar to the top coat 209 described with respect to Fig. 6.
• the process of forming the four layer (205, 1206, 1000, 1208) barrier layer 124 is illustrated.
• the embodiment of Fig. 11 shows the flow chart corresponding to the process illustrated in Figs. 10A to 10F.
• the material 1206a for forming the chamber layer is coated over the primer layer 205.
• step 1120 and in Fig. 10C material 1000a for forming a photon barrier layer is coated over the chamber layer 1206 and the material 1206a.
• step 1130 and in Fig. 10D material 1208a for the nozzle layer is coated over the photon barrier layer material 1000a.
• step 1140 and in Fig. 10E the nozzle layer 1208 and the photon barrier layer 1000 is exposed. The material 1206a remains in the chamber 202 and the materials 1000a and 1208a remain in the nozzle 105.
• the materials 1206a, 1000a, and 1208a are developed and thereby removed from the chamber and nozzle.
• the photon barrier layer 1000 is cast from a solution comprising at least one of an epoxy or acrylic resin, a binder, a solvent, a PAG (photosensitive), and an i-line dye (photon barrier).
• the thickness of photon barrier layer 1000 is in the range of about l A microns to 2 microns, preferably VT. micron.
• the photon barrier layer is minimized, while being sufficiently absorbent.
• the chamber layer 1206 and the nozzle layer 1208 are formed of a material similar to that of layer 207 described above.
• the layer 1206 has a material similar to that of the layer 206.
• the photon barrier layer 1000 is formed of SU8 with photobleachable dye, similar to that described with respect to an embodiment of layer 206 above.
• the SU8 with photobleachable dye allows greater dimensional control and straighter edges. For example, as shown in Fig. 10F, the corner edges between the chamber and nozzle are substantially square edges.
• an additional top coat 209 is formed over the nozzle layer 1208.
• the top coat 209 is similar to the top coat 209 described with respect to Fig. 6.
• at least one of the layers in the cover layer 124 in one of the previous embodiments is formed with the same initial basic coating material.
• the one layer is exposed to a different dose of electromagnetic energy or cured at a different temperature than the remaining layers of the cover layer 124.
• the materials for the layers of the cover layer 124 are chosen for at least one of the following characteristics: CTE matching, ink resistance, stress relief, non-wetting ability, wetting ability, ability to photocure, high resolution processing capability, smooth surface, compatibility, and intermixing capability.
• At least one of the layers in the cover layer 124 in one of the previous embodiments is formed with a material that is patterned, or etched using at least one of the following methods: abrasive sand blasting, dry etch, wet etch, UV assisted wet etch, exposure and developing, DRIE, and UV laser machining.
• at least one of the layers in the cover layer 124 in one of the previous embodiments is formed with a dry film.
• the materials forming the primer, chamber and/or nozzle layers are photodefined through i-line exposure. The i-line exposure is a type of exposure, in particular, about 365 nm wavelength exposure. In one embodiment, this photodefined pattern is covered with a resist material.
• the resist is a positive photoresist, in a particular embodiment it is SPR-220.
• the resist is typically baked in a convection oven at a temperature between 110°C and 190°C to stabilize the resist for the subsequent planarization and bore or nozzle layer processing.
• the solvent develop process that removes the unexposed chamber and nozzle layers is also used to remove the resist.
• at least one of the above-described embodiments maximizes trajectory control by reducing orifice-chamber alignment variability.
• ratios of SU8 ingredients, additives, and molecular weights of the SU8 oligomers are adjusted to give a range in the materials properties that are mentioned above.
• the present invention is not limited to thermally actuated fluid ejection devices, but may also include, for example, piezoelectric activated fluid ejection devices, and other mechanically actuated printheads, as well as other fluid ejection devices.
• the cover layer 124 of the present invention includes a plurality of layers, such as 4 layers, 5 layers, 6 layers, etc. Each of these layers may have either the same or a different material composition, depending upon the application.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Particle Formation And Scattering Control In Inkjet Printers (AREA)
• Laminated Bodies (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Coating Apparatus (AREA)

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• 2003
  • 2003-09-17 JP JP2005509543A patent/JP2007528803A/ja active Pending
  • 2003-09-17 DE DE60317247T patent/DE60317247T2/de not_active Expired - Lifetime
  • 2003-09-17 ES ES03759379T patent/ES2295637T3/es not_active Expired - Lifetime
  • 2003-09-17 KR KR1020067004418A patent/KR101012210B1/ko active IP Right Grant
  • 2003-09-17 AT AT03759379T patent/ATE376935T1/de not_active IP Right Cessation
  • 2003-09-17 WO PCT/US2003/029809 patent/WO2005035255A1/en active IP Right Grant
  • 2003-09-17 AU AU2003275109A patent/AU2003275109A1/en not_active Abandoned
  • 2003-09-17 EP EP03759379A patent/EP1680278B1/de not_active Expired - Lifetime
  • 2003-09-17 CN CNB038270722A patent/CN100421945C/zh not_active Expired - Lifetime

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