EP0375399A2
Expired / Lapsed
EP
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Adhesion layer for platinum based sensors
Assignee: Honeywell Inc
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Filing: 1989-12-20
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Granted: —
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Expires: 2009-12-20
Abstract
Abstract The marginal adhesion of platinum to silicon nitride is a serious issue in the fabrication of microbridge mass air flow sensors. High temperature stabilization anneals (500-1000°C) are necessary to develop the properties and stability necessary for effective device operation. However, the annealing process results in a significant reduction in the already poor platinum/silicon nitride adhesion. Annealing at relatively high temperatures leads to the development of numerous structural defects and the production of non-uniform and variable sensor resistance values. The use of a thin metal oxide adhesion layer (44, 46), approximately 20 to 100 angstroms in thickness is very effective in maintaining platinum (45) adhesion to silicon nitride (42, 47), and through the high temperature anneal sequence. Moreover, incorporation of the thin metal oxide adhesion layer (44, 46) minimizes the development of structural defects, and results in significantly improved uniformity and control of platinum sensor/heater resistance characteristics.
Inventors
- 👤 Robert G. Johnson
- 👤 Ronald B. Foster
- 👤 James O. Holmen
- 👤 Uppili Sridhar
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 14:46
CPC Classifications
G; G01; G01F; G01F1/00; G01F1/68; G01F1/684; G01F1/6845; H; H01; H01C; H01C7/00; H01C7/006
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
94 words
A thin film platinum on silicon nitride sensor structure with an adhesion enhancement interlayer, the sensor structure characterised by: a layer of silicon nitride (42) having a surface on which it is desired to deposit an electrically resistive thin film layer of platinum (44); a thin film interlayer (44) of a metal oxide deposited on said silicon nitride surface (43) as an adhesion promoter for platinum; and a thin film of platinum (45) deposited on said metal outside interlayer whereby the metal oxide interlayer (44) enhances the bond of platinum to silicon nitride (42).
Claim 2
Dependent Claim
94 words
A thin film platinum on silicon nitride sensor structure with an adhesion enhancement interlayer, the sensor structure characterised by: a layer of silicon nitride (42) having a surface on which it is desired to deposit an electrically resistive thin film layer of platinum (44); a thin film interlayer (44) of a metal oxide deposited on said silicon nitride surface (43) as an adhesion promoter for platinum; and a thin film of platinum (45) deposited on said metal outside interlayer whereby the metal oxide interlayer (44) enhances the bond of platinum to silicon nitride (42).
Claim 3
Dependent Claim
26 words
The structure according to Claim 1 characterised in that the thin film layer of metal oxide has a thickness of the order of about 50 angstroms.
Claim 4
Dependent Claim
24 words
A structure according to Claim 1 or 2 characterised in that the thin film layer of metal oxide and of platinum are sputtered depositions.
Claim 5
Dependent Claim
97 words
A thin film platinum-based sensor structure characterised by: a substrate of silicon (40) having a first surface (41); a thin film of silicon nitride (42) on said silicon surface; a thin film interlayer of a metal oxide (44) deposited on said silicon nitride; a thin film of platinum (45) deposited on said metal oxide interlayer whereby the metal oxide interlayer enhances the bond of platinum to silicon nitride; a second thin film layer of metal oxide (46) over said platinum; and a passivating silicon nitride layer (42) over said second metal oxide layer and said platinum layer.
Claim 6
Dependent Claim
97 words
A thin film platinum-based sensor structure characterised by: a substrate of silicon (40) having a first surface (41); a thin film of silicon nitride (42) on said silicon surface; a thin film interlayer of a metal oxide (44) deposited on said silicon nitride; a thin film of platinum (45) deposited on said metal oxide interlayer whereby the metal oxide interlayer enhances the bond of platinum to silicon nitride; a second thin film layer of metal oxide (46) over said platinum; and a passivating silicon nitride layer (42) over said second metal oxide layer and said platinum layer.
Claim 7
Dependent Claim
28 words
A structure according to Claim 4 characterised in that the thin film layer of metal oxide has a thickness in the range of about 20 to 100 angstroms.
Claim 8
Dependent Claim
22 words
A structure according to Claim 4 or 5 characterised in that the metal oxide, platinum and metal oxide layers are sputter depositions.
Claim 9
Dependent Claim
37 words
A structure according to any preceding Claim characterised in that the metal oxide is selected from the group of oxides consisting of oxides of metals of Groups III, IV, V, VI or VIII of the Periodic Table.
Claim 10
Dependent Claim
31 words
A structure according to any preceding Claim characterised in that the metal oxide is selected from the group consisting of chromium oxide, titanium oxide, tantalum oxide, nickel oxide, and aluminium oxide.
Claim 11
Independent Claim
95 words
A method of fabricating a high-adhesion platinum-based sensor on a silicon nitride base characterised by the steps of: providing a silicon nitride layer (42) having a surface (43) upon which it is desired to deposit an electrically resistive path of platinum; depositing a thin film interlayer (44) of a metal oxide on said silicon nitride surface as an adhesion promoter for platinum; depositing a thin film of platinum (45) on said metal oxide interlayer whereby the metal oxide interlayer enhances the bond of platinum to silicon nitride so that a high adhesion platinum layer results.
Claim 12
Independent Claim
95 words
A method of fabricating a high-adhesion platinum-based sensor on a silicon nitride base characterised by the steps of: providing a silicon nitride layer (42) having a surface (43) upon which it is desired to deposit an electrically resistive path of platinum; depositing a thin film interlayer (44) of a metal oxide on said silicon nitride surface as an adhesion promoter for platinum; depositing a thin film of platinum (45) on said metal oxide interlayer whereby the metal oxide interlayer enhances the bond of platinum to silicon nitride so that a high adhesion platinum layer results.
Claim 13
Dependent Claim
21 words
A method according to Claim 9 characterised in that the depositing of metal oxide and of platinum is by sputter deposition.
Claim 14
Independent Claim
124 words
A method of fabricating a high-adhesion platinum-based sensor structure, the steps characterised by: providing a substrate of silicon (4)) having a thin film of silicon nitride (42) on the surface thereof and upon which it is desired to deposit a thin film layer of platinum; depositing a thin film interlayer (44) of a metal oxide on said silicon nitride; depositing a thin film layer of platinum (45) on said metal oxide interlayer whereby the metal oxide interlayer enhances the bond of platinum to silicon nitride so that a high adhesion platinum layer results; depositing a second thin film interlayer (46) of metal oxide over the platinum; and depositing a passivating silicon nitride layer (47) over said second metal oxide layer and said platinum layer.
Claim 15
Independent Claim
124 words
A method of fabricating a high-adhesion platinum-based sensor structure, the steps characterised by: providing a substrate of silicon (4)) having a thin film of silicon nitride (42) on the surface thereof and upon which it is desired to deposit a thin film layer of platinum; depositing a thin film interlayer (44) of a metal oxide on said silicon nitride; depositing a thin film layer of platinum (45) on said metal oxide interlayer whereby the metal oxide interlayer enhances the bond of platinum to silicon nitride so that a high adhesion platinum layer results; depositing a second thin film interlayer (46) of metal oxide over the platinum; and depositing a passivating silicon nitride layer (47) over said second metal oxide layer and said platinum layer.
Claim 16
Dependent Claim
27 words
A method according to Claim 11 characterised in that the steps of depositing of metal oxide and the step of depositing of platinum are by sputter deposition.
Claim 17
Independent Claim
31 words
A method according to any of Claims 9 to 12 characterised in that the depositing of metal oxide is to a thickness in the range of about 20 - 100 angstroms.
Claim 18
Independent Claim
40 words
A method according the any of Claims 9 to 14 characterised in that the metal oxide is selected from the group of oxides consisting of oxides of metals of Groups III, IV, V, VI, or VIII of the Periodic Table.
Claim 19
Independent Claim
34 words
A method according to any of Claims 9 to 13 characterised in that the metal oxide is selected from the group consisting of chromium oxide, titanium oxide, tantalum oxide, nickel oxide, and aluminium oxide.
References Cited (Backward Citations)
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