EP0688672B1 - Tintenstrahldruckkopf mit einer Kavitationssperrschicht von Palladium und einer Verbindungsschicht - Google Patents
Tintenstrahldruckkopf mit einer Kavitationssperrschicht von Palladium und einer Verbindungsschicht Download PDFInfo
- Publication number
- EP0688672B1 EP0688672B1 EP95302093A EP95302093A EP0688672B1 EP 0688672 B1 EP0688672 B1 EP 0688672B1 EP 95302093 A EP95302093 A EP 95302093A EP 95302093 A EP95302093 A EP 95302093A EP 0688672 B1 EP0688672 B1 EP 0688672B1
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- EP
- European Patent Office
- Prior art keywords
- layer
- palladium
- resistor
- ink
- electrically
- Prior art date
- Legal status (The legal status 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 status listed.)
- Expired - Lifetime
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- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 title claims description 98
- 229910052763 palladium Inorganic materials 0.000 title claims description 49
- 230000004888 barrier function Effects 0.000 title claims description 30
- 238000002161 passivation Methods 0.000 claims description 22
- 239000000758 substrate Substances 0.000 claims description 17
- 239000004020 conductor Substances 0.000 claims description 16
- 239000000463 material Substances 0.000 claims description 14
- 238000000034 method Methods 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 9
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 6
- 229910052710 silicon Inorganic materials 0.000 claims description 5
- 239000010703 silicon Substances 0.000 claims description 5
- 238000000151 deposition Methods 0.000 claims description 3
- 230000008878 coupling Effects 0.000 claims 1
- 238000010168 coupling process Methods 0.000 claims 1
- 238000005859 coupling reaction Methods 0.000 claims 1
- 238000005530 etching Methods 0.000 claims 1
- 239000010410 layer Substances 0.000 description 110
- 239000000976 ink Substances 0.000 description 48
- 229910052715 tantalum Inorganic materials 0.000 description 30
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 30
- 239000010931 gold Substances 0.000 description 18
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 17
- 229910052737 gold Inorganic materials 0.000 description 17
- 229910052782 aluminium Inorganic materials 0.000 description 16
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 15
- 238000010438 heat treatment Methods 0.000 description 13
- 238000010304 firing Methods 0.000 description 12
- 229910052581 Si3N4 Inorganic materials 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 6
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 5
- 239000001257 hydrogen Substances 0.000 description 5
- 229910052739 hydrogen Inorganic materials 0.000 description 5
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 238000005299 abrasion Methods 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 229910010271 silicon carbide Inorganic materials 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 238000005476 soldering Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical group [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 229910052681 coesite Inorganic materials 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 229910052906 cristobalite Inorganic materials 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 230000003628 erosive effect Effects 0.000 description 2
- 229910021472 group 8 element Inorganic materials 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 150000002940 palladium Chemical class 0.000 description 2
- 238000001020 plasma etching Methods 0.000 description 2
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 229910000077 silane Inorganic materials 0.000 description 2
- 229910052682 stishovite Inorganic materials 0.000 description 2
- 229910052905 tridymite Inorganic materials 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- YZCKVEUIGOORGS-UHFFFAOYSA-N Hydrogen atom Chemical compound [H] YZCKVEUIGOORGS-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- RVSGESPTHDDNTH-UHFFFAOYSA-N alumane;tantalum Chemical compound [AlH3].[Ta] RVSGESPTHDDNTH-UHFFFAOYSA-N 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- QZPSXPBJTPJTSZ-UHFFFAOYSA-N aqua regia Chemical compound Cl.O[N+]([O-])=O QZPSXPBJTPJTSZ-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- BGTFCAQCKWKTRL-YDEUACAXSA-N chembl1095986 Chemical compound C1[C@@H](N)[C@@H](O)[C@H](C)O[C@H]1O[C@@H]([C@H]1C(N[C@H](C2=CC(O)=CC(O[C@@H]3[C@H]([C@@H](O)[C@H](O)[C@@H](CO)O3)O)=C2C=2C(O)=CC=C(C=2)[C@@H](NC(=O)[C@@H]2NC(=O)[C@@H]3C=4C=C(C(=C(O)C=4)C)OC=4C(O)=CC=C(C=4)[C@@H](N)C(=O)N[C@@H](C(=O)N3)[C@H](O)C=3C=CC(O4)=CC=3)C(=O)N1)C(O)=O)=O)C(C=C1)=CC=C1OC1=C(O[C@@H]3[C@H]([C@H](O)[C@@H](O)[C@H](CO[C@@H]5[C@H]([C@@H](O)[C@H](O)[C@@H](C)O5)O)O3)O[C@@H]3[C@H]([C@@H](O)[C@H](O)[C@@H](CO)O3)O[C@@H]3[C@H]([C@H](O)[C@@H](CO)O3)O)C4=CC2=C1 BGTFCAQCKWKTRL-YDEUACAXSA-N 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
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- 239000012530 fluid Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- -1 gold-aluminum Chemical compound 0.000 description 1
- 238000007641 inkjet printing Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical group [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 1
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910021332 silicide Inorganic materials 0.000 description 1
- FVBUAEGBCNSCDD-UHFFFAOYSA-N silicide(4-) Chemical compound [Si-4] FVBUAEGBCNSCDD-UHFFFAOYSA-N 0.000 description 1
- 150000003377 silicon compounds Chemical class 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 239000007779 soft material Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
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- 238000004544 sputter deposition Methods 0.000 description 1
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- 230000008646 thermal stress Effects 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
Images
Classifications
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- 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
- B41J2/1646—Manufacturing processes thin film formation thin film formation by sputtering
-
- 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
- B41J2/1623—Manufacturing processes bonding and adhesion
-
- 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
- B41J2/164—Manufacturing processes thin film formation
- B41J2/1642—Manufacturing processes thin film formation thin film formation by CVD [chemical vapor deposition]
Definitions
- the present invention generally relates to a printhead for a thermal inkjet printer print cartridge and more particularly to a thermal inkjet cartridge printhead and associated interconnect and method for making the same which has fewer process steps required in the construction of the printhead substrate since one layer of palladium forms both the cavitation barrier layer and the interconnect layer.
- a printhead cartridge typically consists of one or more encased reservoirs of ink fluidically coupled to a small laminated structure (a printhead) having many interconnected ink channels and chambers which terminate in very small orifices in the printhead outer layer (the orifice plate).
- a printhead a small laminated structure
- the orifice plate the small orifices are arranged in such a fashion in the orifice plate that the expulsion of a droplet of ink from a determined number of orifices relative to a particular position of the medium results in the production of a portion of a desired character or image. Controlled repositioning of the substrate or the medium and another expulsion of ink droplets continues the production of more portion of the desired character or image.
- Expulsion of the ink droplet in a conventional thermal inkjet printer is a result of rapid thermal heating of the ink to a temperature which exceeds the boiling point of the ink solvent and creates a gas phase bubble of ink.
- Each orifice is coupled to a small unique chamber filled with ink and having an individually addressable heating element in thermal contact with the ink.
- the bubble nucleates and expands, it displaces a volume of ink which is forced out of the orifice and deposited on the medium. The bubble then collapses and the displaced volume of ink is replenished from the larger ink reservoir.
- a common failure mode of the inkjet printhead is that of erosion of the heating element and its associated protective layer found in each of the ink firing chambers by the thermal stresses created by the rapid activation of the heating element, the mechanical abrasion of the surface by the collapsing ink bubble after expulsion of ink, and the chemical attack by aggressive ink components.
- the heating element is overlain with a passivation layer of silicon nitride and carbide designed to protect the heating element form the corrosive action of the heated ink.
- a passivation layer of silicon nitride and carbide designed to protect the heating element form the corrosive action of the heated ink.
- a cavitation barrier layer to protect the structure from direct mechanical damage to the passivation layers and heating element.
- this layer is constructed of tantalum but tungsten or molybdenum have been suggested as alternative materials.
- JP-A-01087272 describes an electrothermal recording head for an electrothermal printer.
- the recording head comprises a plurality of electrode elements comprising a platinum group metal, which may be palladium.
- JP-A-01037894 also describes an electrothermal recording head.
- the heating resistor is formed from a multilayer structure comprising a substrate, a lower conductive layer, a thin insulating layer, and an upper conductive layer.
- the conductive layers may be formed of palladium.
- the present invention provides a print head for a thermal inkjet printer and a method of manufacture thereof as designed in the accompanying claims.
- the present invention encompasses a thermal inkjet cartridge having a printhead which employs a layer of palladium as both the cavitation barrier and the electrical interconnect layer for reduced manufacturing costs and high reliability.
- FIG. 1 is a view of a portion of a thermal inkjet printhead illustrating an ink firing chamber 101 and an orifice 103 associated with the ink firing chamber 101. Part of a second orifice 105 associated with another ink firing chamber is also shown. Many orifices are typically arranged in a predetermined pattern on the orifice plate so that the ink which is expelled from selected orifices creates a defined pattern of print on the medium. Generally, the medium is maintained in a position which is parallel to the external surface of the orifice plate. Ink is supplied to the firing chamber 101 via an opening 107 to replenish ink which has been expelled from orifice 103 when ink has been vaporized by localized heating from a heating structure 109.
- the ink firing chamber is bounded by walls created by an orifice plate 111, a layered silicon substrate 113, and walls 115, 117 created by an ink barrier layer.
- FIG. 2 A cross section of a conventional inkjet firing chamber taken through the heating structure 109 is shown in FIG. 2. The features of the various layers deposited on the substrate 113 are shown in greater detail but the relative thicknesses of the layers is exaggerated for ease of viewing.
- a p-type silicon substrate 201 is covered with a thermally grown field oxide SiO 2 as an underlayer 203 to the remainder of the structure.
- a layer 205 of Tantalum-Aluminum (TaAl) is conventionally deposited on the surface of the SiO 2 layer 203 and, because of its relatively high electrical resistance, forms a resistive layer.
- a layer 207 of aluminum (Al) is selectively deposited on the TaAl layer 205, leaving open areas (such as area 209) to the TaAl layer 205. Because of the relatively low electrical resistance of the aluminum layer 207, the high resistance of the TaAl layer 205 is effectively shorted by the aluminum layer 207 except in the open area 209. The resulting area 209 is a resistor capable of rapid electrical resistance heating.
- a passivation layer 213 consisting of silicon nitride (SiN) and silicon carbide (SiC) is selectively deposited over the structure. This passivation layer 213 is masked and selective openings 219, 221 to the aluminum conductor layer 207 are created.
- a layer of tantalum 215 is selectively deposited over the passivation-protected resistor area 209 and over openings 219, 221 to the aluminum conductive layer 207 such that an electrical contact between the tantalum layer 215 and the aluminum layer 207 is established at the openings 219, 221.
- the selective deposition of tantalum allows interconnection between contact openings and to external circuitry such that relatively complex electrical interconnections are realized.
- Tantalum is a relatively hard material and resists the mechanical abrasion from the collapsing ink bubble following ink nucleation in the firing chamber. Tantalum also exhibits good adhesion to the passivation layer 213.
- a layer of gold 227 is selectively placed over the tantalum layer 215 to provide a surface for bonding.
- the gold layer is not placed or retained in the ink firing chamber (i.e., over resistor area 209) because gold does not provide adequate protection from mechanical abrasion. It is important to note that additional processing steps are required to selectively place the gold layer 227 over the tantalum layer 215.
- a cavitation barrier 215 consisting of tantalum (Ta) is selectively deposited over the passivation layer 213 in the ink firing chamber to protect against the fluid turbulence and abrasion created by the collapsing ink bubble.
- the layer of tantalum is discontinuously extended to cover additional surfaces of the substrate and various layers.
- the passivation layer 213 has been selectively removed to provide exposure to the aluminum conductor layer 207.
- Tantalum interconnect layers are selectively deposited over the exposed aluminum conductor layer 207 and the passivation layer 213.
- a gold (Au) interconnect layer 227 is deposited over the tantalum interconnect layers to provide a layer to which external electrical connections can be made, by bonding, soldering, or by contact, to an oxidation free surface. Electrical connections to the inkjet printer electronics external to the inkjet print cartridge are then accomplished by bonding, soldering, or otherwise connecting to the gold interconnect layer 227, as shown at 231. A similar connection may be made to other portions of the gold interconnect layer 227 to complete the electrical circuit for energizing the resistive heater area.
- a preferred embodiment of a printhead employing the present invention is illustrated in the cross sectional view of FIG. 3. It is a feature of the present invention that the process-intensive method utilizing both a tantalum and a gold interconnect layer as well as a tantalum cavitation layer have been eliminated.
- a single material layer 303 consisting of palladium (Pd) is deposited over the passivation layer 213 in the resistor area 209 to provide the necessary cavitation barrier over the resistor. In the preferred embodiment, this palladium cavitation barrier layer 303 extends throughout the bottom surface of the ink firing chamber and terminates beneath the ink barrier layer 115 and 117.
- the palladium layer 303 is selectively deposited over the exposed aluminum conductor layer 207 at the locations 219 and 221 so that an electrical connection may be realized to the aluminum conductor layer 207.
- This palladium layer 303 is also selectively deposited over the passivation layer 213 so that an electrical connection to the aluminum conductor layer 207 may be extended to a point where a connection to the inkjet printer may be made by bonding, soldering, or contacting a wire or other external electrical lead, such as shown at 311. It can be appreciated that an electrical connection made at point 311 is coupled to the aluminum conductor layer 207 at area 219.
- the printhead in the preferred embodiment, is manufactured using the following steps.
- the p-type silicon substrate 201 for example a monocrystalline silicon structure doped with boron
- the electrically resistive layer of TaAl 205 is a mixture formed, in the preferred embodiment, by cosputtering both materials such that the deposited mixture is approximately 50 atomic (at.)% of Ta and 50 at. % Al and has a thickness of between 770 and 890 angstroms.
- the resistive layer may be of phosphorus-doped polycrystalline silicon.
- the conductive layer 207 is applied directly to the TaAl resistive layer 205 using conventional sputtering or vapor deposition techniques to deposit a layer of between 4000 and 6000 angstroms of Al. (In the preferred embodiment, the material composition is approximately 95.5% by weight aluminum).
- the layered substrate, at this point in its process, is then masked and etched (preferably using known plasma etching techniques) in order to produce exposed areas of the TaAl resistive layer 205 (such as area 209) and to remove both the Al conductive layer 207 and the TaAl resistive layer 205 (such as at area 315).
- the passivation layer 213 is then deposited over the remaining layers to provide protection from the corrosive action of the ink used in the inkjet printer for these layers.
- a first sublayer of silicon nitride is deposited from the decomposition of silane mixed with ammonia at a pressure of about 2 torr at a temperature from 300°C to 400°C. This first sublayer is deposited as a thickness of between 4000 and 6000 angstroms.
- a second passivation sublayer of silicon carbide formed by plasma enhanced chemical vapor deposition (PECVD) using silane and methane at a temperature of about 300°C to 400°C.
- PECVD plasma enhanced chemical vapor deposition
- This composite passivation layer 213 is subsequently masked and etched using reactive ion etching techniques or other chemical means to provide openings to the aluminum conductor layer 207 (at areas 219 and 221).
- the passivation layer is thereby separated into a portion covering the resistor area 209 and extending beneath the ink barrier layers 115 and 117, and a portion extending from beneath the ink barrier layer to the connection area 315. It is an important feature of the present invention that a single layer of palladium is then deposited upon selected areas of the layered substrate to provide both a cavitation layer over area 209 and an interconnect layer to which an electrical connection can be made at 311.
- a palladium target is sputtered in thin layer deposition on the layered substrate, producing a thin film layer of palladium between 4000 and 9000 angstroms thick of 99.95% wt. palladium.
- the palladium layer 303 is then masked and etched into electrically insulated portions such as the portion over the resistor area 209 (which portion forms the cavitation barrier) and portions, which are electrically insulated from each other, over contact areas 219 and 221.
- the ink barrier layer 115, 117 is selectively applied to and above the cavitation barrier of layer 303 (at area 209), portions of the interconnect portion of layer 303, and portions of the passivation layer 213, essentially as indicated in FIG. 3.
- This ink barrier layer 115,117 is preferably made of an organic polymer plastic, such as products sold under the names VACREL and RISTON by E. I. DuPont de Nemours and Co.
- the ink barrier layer is applied by conventional lamination techniques to a thickness of between 20 and 30 microns.
- a conventional orifice plate 111 (which, in the preferred embodiment is made of gold plated nickel) is applied to the ink barrier layer 115, 117 in a manner which orients each orifice over the ink firing chamber and above the heater resistor.
- additional processing steps may be included, such as those described in US Patent No. 5,159,353, to produce other semiconductor elements which provide additional functions such as signal multiplexing or printhead identification.
- palladium is considered to be a noble element by the electro-chemical industry. Palladium is also a face-centered-cubic material which exhibits twelve independent planes of slippage which would lead a casual observer to conclude that palladium would be a mechanically soft material, unsuitable for use as a cavitation barrier. Furthermore, the specific heat of palladium is higher than that of tantalum, also suggesting that palladium would be inferior to tantalum in an environment requiring heat conduction. Thus, although palladium is a group VIII element, its use as a cavitation barrier material has not been apparent to those working in the field of inkjet printheads.
- the passivation layer 213 (consisting of silicon nitride and silicon carbide in the preferred embodiment) yields atomic hydrogen when exposed to high temperatures. It has become known that hydrogen can build up under a cavitation barrier due to the high temperature operation of the heater resistor.
- a tantalum cavitation barrier is relatively impervious to the passage of hydrogen and it is believed that one failure mechanism in thermal inkjet print heads is related to failure of the tantalum cavitation barrier due to hydrogen build-up.
- a similar layer of palladium has the ability to absorb 300 times its volume of hydrogen during use such as inkjet printhead operation.
- Palladium has a higher oxidation temperature than tantalum so it is more resistant to oxidation and, for the range of pH expected in inks used in inkjet printers (5.0-9.0), palladium is stable and non-corroding (Pourbaux, "Atlas of Electromechanical Equilibrium in Aqueous Solutions”). However, palladium can be etched with aqua regia to easily realize desired interconnection patterns for the printhead.
- the two materials are nearly the same in applications involving heat transfer.
- Palladium also has advantages when used as the common cavitation barrier and electrical interconnect layer 303.
- Prior designs have used gold overlaying tantalum as the interconnect layer to reduce gold-aluminum interactions which produce both high resistance interconnects with positive volume expansion intermetallic byproducts.
- the conductivity of palladium (11x10 -6 ohm-cm) is sufficient for the material to be a good conductor for the current densities employed in thermal inkjet printer printheads.
- palladium accepts direct thermal compression bonding of external leads so the two-element dual layer of gold overlaying tantalum for an interconnect layer becomes unnecessary.
- the price of palladium is approximately one-third to one-fifth that of gold in a sputter target configuration.
- Palladium represents a combination of good mechanical resistance, good thermal performance, high temperature resistance to oxidation and corrosion, bondability, and high electrical conductivity. Although palladium has properties which are not superior to all properties of gold or to all properties of tantalum, it has certain properties not shared by both but which enable it alone to perform well the roles of both elements for the dual purpose of cavitation barrier layer and interconnect layer in a printhead environment. These advantageous properties have not previously been realized or exploited in a thermal inkjet printhead environment. Thus, the use of palladium for both cavitation barrier and interconnect layer reduces the number of steps required in the manufacture of such an inkjet printhead and provides improved performance at lower manufacturing costs.
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Particle Formation And Scattering Control In Inkjet Printers (AREA)
Claims (3)
- Ein Druckkopf für einen thermischen Tintenstrahldrucker, der folgende Merkmale aufweist:ein Substrat (201, 203), das eine resistive Schicht (205) aufweist, die in einem Bereich auf einer Oberfläche des Substrats angeordnet ist;eine Schicht aus leitfähigem Material (207), die auf der resistiven Schicht außer in einem vorbestimmten Bereich, der einem Widerstand entspricht, angeordnet ist;eine elektrisch isolierende Passivierungsschicht (213), die mindestens auf und benachbart zu dem Widerstandsbereich angeordnet ist; undeine gemeinsame Hohlraumbarrieren- und Elektroverbindungsschicht (303), die lediglich aus Palladium besteht, und die einen ersten Abschnitt, der auf der elektrisch isolierenden Passivierungsschicht (213) mindestens in dem Widerstandsbereich angeordnet ist, und einen zweiten Abschnitt aufweist, der von dem ersten Abschnitt, der auf der elektrisch isolierenden Passivierungsschicht (213) angeordnet ist, elektrisch getrennt ist, und der den Widerstandsbereich mit einer elektrischen Verbindung elektrisch koppelt.
- Ein Verfahren zum Herstellen eines Druckkopfs für einen thermischen Tintenstrahldrucker, das folgende Schritte aufweist:selektives Plazieren einer Schicht aus resistivem Material (205) auf einer oxidierten Oberfläche (203) eines Siliziumsubstrats (201);Plazieren einer ersten Schicht aus leitfähigem Material (207) mindestens auf der Schicht des resistiven Materials außer in einem vorbestimmten Bereich, der einem Widerstand entspricht; undPlazieren einer elektrisch isolierenden Passivierungsschicht (213) auf der ersten Schicht aus leitfähigem Material (201) und der oxidierten Oberfläche (203) des Siliziumsubstrats (201) außer in mindestens einem vorbestimmten Bereich des leitfähigen Materials (207);Plazieren einer einzigen elektrisch unterbrochenen zweiten Schicht (303) aus Palladium auf der Passivierungsschicht und auf dem mindestens einen vorbestimmten Bereich aus leitfähigem Material, wodurch eine elektrische Verbindung mit dem Widerstand durch einen ersten Abschnitt der zweiten Schicht aus Palladium hergestellt wird, jedoch ohne eine elektrische Verbindung mit einem zweiten Abschnitt der zweiten Schicht (303) aus Palladium, die über dem Bereich angeordnet ist, der einem Widerstand entspricht; undVerbinden einer elektrischen Zuleitung (311) mit dem ersten Abschnitt der elektrisch unterbrochenen zweiten Schicht aus Palladium, wodurch eine Verbindung mit einer äußeren Schaltungsanordnung des Tintenstrahldruckers hergestellt werden kann.
- Ein Verfahren zum Herstellen gemäß Anspruch 2, bei dem der Schritt des Plazierens einer elektrisch unterbrochenen zweiten Schicht (303) aus Palladium ferner die Schritte des Aufbringens einer Schicht aus Palladium und des selektiven Ätzens der Schicht aus Palladium (303) in den ersten und den zweiten Abschnitt, die elektrisch getrennt sind, aufweist.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US26547094A | 1994-06-24 | 1994-06-24 | |
US265470 | 1994-06-24 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0688672A1 EP0688672A1 (de) | 1995-12-27 |
EP0688672B1 true EP0688672B1 (de) | 1999-06-16 |
Family
ID=23010576
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP95302093A Expired - Lifetime EP0688672B1 (de) | 1994-06-24 | 1995-03-29 | Tintenstrahldruckkopf mit einer Kavitationssperrschicht von Palladium und einer Verbindungsschicht |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0688672B1 (de) |
JP (1) | JPH081943A (de) |
DE (1) | DE69510275T2 (de) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6126277A (en) * | 1998-04-29 | 2000-10-03 | Hewlett-Packard Company | Non-kogating, low turn on energy thin film structure for very low drop volume thermal ink jet pens |
US6051867A (en) * | 1999-05-06 | 2000-04-18 | Hewlett-Packard Company | Interlayer dielectric for passivation of an elevated integrated circuit sensor structure |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5515815A (en) * | 1978-07-19 | 1980-02-04 | Toshiba Corp | Method of manufacturing thin film thermal head |
US4535343A (en) * | 1983-10-31 | 1985-08-13 | Hewlett-Packard Company | Thermal ink jet printhead with self-passivating elements |
JPS6437894A (en) * | 1987-08-03 | 1989-02-08 | Oki Electric Ind Co Ltd | Heating resistor |
JPS6487272A (en) * | 1987-09-30 | 1989-03-31 | Canon Kk | Electrothermal recording head |
-
1995
- 1995-03-29 EP EP95302093A patent/EP0688672B1/de not_active Expired - Lifetime
- 1995-03-29 DE DE69510275T patent/DE69510275T2/de not_active Expired - Lifetime
- 1995-06-23 JP JP7180938A patent/JPH081943A/ja active Pending
Also Published As
Publication number | Publication date |
---|---|
DE69510275D1 (de) | 1999-07-22 |
JPH081943A (ja) | 1996-01-09 |
EP0688672A1 (de) | 1995-12-27 |
DE69510275T2 (de) | 1999-10-14 |
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