US4791398A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thin film platinum resistance thermometer with high temperature diffusion barrier
Assignee: Rosemount Inc
•
Filing: 1986-02-13
•
Granted: 1988-12-13
•
Expires: 2006-02-13
Abstract
Abstract A thin film platinum resistance thermometer capable of operation at elevated temperatures includes a benign dielectric layer covering the thin film platinum resistance temperature sensing element and a barrier layer overlying the dielectric layer. The barrier layer, which is preferrably titanium dioxide, resists diffusion of contaminants which would alter the electrical characteristics of the sensing element, while permitting diffusion of oxygen through the barrier layer.
Inventors
- 👤 Fred C. Sittler
- 👤 Adrian C. Toy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 10:53
CPC Classifications
G; G01; G01K; G01K7/00; G01K7/16; G01K7/18; G01K7/183; H; H01; H01C; H01C1/00; H01C1/02; H01C1/028; H01C7/00; H01C7/02; H01C7/021
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
65 words
A temperature sensor comprising: an electrically insulating substrate; a resistance temperature sensing element formed of platinum on a first surface of the substrate; a benign dielectric layer covering the temperature sensing element; and a barrier layer overlying the dielectric layer which resists diffusion of contaminants into the platinum while permitting diffusion of oxygen through the barrier layer such that the platinum is protected from contamination.
Claim 2
Dependent Claim
65 words
A temperature sensor comprising: an electrically insulating substrate; a resistance temperature sensing element formed of platinum on a first surface of the substrate; a benign dielectric layer covering the temperature sensing element; and a barrier layer overlying the dielectric layer which resists diffusion of contaminants into the platinum while permitting diffusion of oxygen through the barrier layer such that the platinum is protected from contamination.
Claim 3
Dependent Claim
13 words
The temperature sensor of claim 1 wherein the barrier layer is titanium dioxide.
Claim 4
Dependent Claim
28 words
The temperature sensor of claim 2 wherein the barrier layer is formed by deposition of titanium and subsequent heat treatment in an oxygen atmosphere to form titanium dioxide.
Claim 5
Dependent Claim
19 words
The temperature sensor of claim 2 wherein the barrier layer has a thickness between about 6000 and 12,000 Angstroms.
Claim 6
Dependent Claim
13 words
The temperature sensor of claim 1 wherein the dielectric layer is silicon dioxide.
Claim 7
Dependent Claim
18 words
The temperature sensor of claim 5 wherein the dielectric layer is formed by a chemical vapor deposition process.
Claim 8
Dependent Claim
16 words
The temperature sensor of claim 6 wherein the chemical vapor deposition process uses a TEOS source.
Claim 9
Dependent Claim
20 words
The temperature sensor of claim 5 wherein the dielectric layer has a thickness of between about 2000 and 4000 Angstroms.
Claim 10
Dependent Claim
11 words
The temperature sensor of claim 1 wherein the substrate is sapphire.
Claim 11
Dependent Claim
97 words
A protective coating for preventing degradation at elevated temperatures which exceed about 400° C., of electrical characteristics of a resistance temperature sensing element formed of platinum, the protective coating comprising: a benign dielectric layer formed of a material substantially free of alkaline metal oxides covering a surface of the resistance temperature sensing element; and a barrier layer covering the dielectric layer, the barrier layer being formed of a material which, at the elevated temperatures, resists diffusion therethrough of contaminants into the resistance temperature sensing element which would alter the electrical characteristics of the resistance temperature sensing element.
Claim 12
Dependent Claim
97 words
A protective coating for preventing degradation at elevated temperatures which exceed about 400° C., of electrical characteristics of a resistance temperature sensing element formed of platinum, the protective coating comprising: a benign dielectric layer formed of a material substantially free of alkaline metal oxides covering a surface of the resistance temperature sensing element; and a barrier layer covering the dielectric layer, the barrier layer being formed of a material which, at the elevated temperatures, resists diffusion therethrough of contaminants into the resistance temperature sensing element which would alter the electrical characteristics of the resistance temperature sensing element.
Claim 13
Dependent Claim
91 words
A protective coating for preventing degradation at elevated temperatures which exceed about 400° C., of electrical characteristics of a resistance temperature sensing element formed of platinum, the protective coating comprising: a benign dielectric layer covering a surface of the resistance temperature sensing element; and a barrier layer covering the dielectric layer, the barrier layer being formed of a material which, at the elevated temperatures, resists diffusion therethrough of contaminants into the platinum which would alter the electrical charateristics of the resistance temperature sensing element, wherein the barrier layer is titanium dioxide.
Claim 14
Dependent Claim
91 words
A protective coating for preventing degradation at elevated temperatures which exceed about 400° C., of electrical characteristics of a resistance temperature sensing element formed of platinum, the protective coating comprising: a benign dielectric layer covering a surface of the resistance temperature sensing element; and a barrier layer covering the dielectric layer, the barrier layer being formed of a material which, at the elevated temperatures, resists diffusion therethrough of contaminants into the platinum which would alter the electrical charateristics of the resistance temperature sensing element, wherein the barrier layer is titanium dioxide.
Claim 15
Dependent Claim
27 words
The invention of claim 11 wherein the barrier layer is formed by deposition of titanium and subsequent heat treatment in an oxygen atmosphere to form titanium dioxide.
Claim 16
Dependent Claim
16 words
The invention of claim 11 wherein the barrier layer has a thickness of about 6000 Angstroms.
Claim 17
Dependent Claim
12 words
The invention of claim 10 wherein the dielectric layer is silicon dioxide.
Claim 18
Dependent Claim
17 words
The invention of claim 14 wherein the dilectric layer is formed by a chemical vapor deposition process.
Claim 19
Dependent Claim
15 words
The invention of claim 15 wherein the chemical vapor deposition process is a TEOS process.
Claim 20
Dependent Claim
16 words
The invention of claim 14 wherein the dielectric layer has a thickness of about 2000 Angstroms.
Claim 21
Independent Claim
71 words
A method of forming a thin film resistance temperature sensor, the method comprising; forming a thin film platinum resistance element on a substrate; covering the resistance element with a first layer of a benign dielectric material; and forming, over the first layer, a second layer of a selective barrier material which resists diffusion therethrough of contaminants which would alter electrical characteristics of the resistance element while permitting diffusion of oxygen therethrough.
Claim 22
Independent Claim
71 words
A method of forming a thin film resistance temperature sensor, the method comprising; forming a thin film platinum resistance element on a substrate; covering the resistance element with a first layer of a benign dielectric material; and forming, over the first layer, a second layer of a selective barrier material which resists diffusion therethrough of contaminants which would alter electrical characteristics of the resistance element while permitting diffusion of oxygen therethrough.
Claim 23
Dependent Claim
12 words
The method of claim 18 wherein the dielectric material is silicon dioxide.
Claim 24
Dependent Claim
24 words
The method of claim 19 wherein covering the resistance element with a first layer comprises depositing silicon dioxide by a chemical vapor deposition process.
Claim 25
Dependent Claim
15 words
The method of claim 20 wherein the chemical vapor deposition process uses a TEOS source.
Claim 26
Dependent Claim
13 words
The method of claim 18 wherein the selective barrier material is titanium dioxide.
Claim 27
Dependent Claim
39 words
The method of claim 22 wherein forming the second layer comprises: depositing a layer of titanium over the first layer; and heat treating the layer of titanium in an oxygen atmosphere to form the second layer of titanium dioxide.
Claim 28
Dependent Claim
27 words
The method of claim 18 wherein the temperature sensor further includes a thin film platinum contact pad on the substrate to which the resistance element is connected.
Claim 29
Dependent Claim
28 words
The method of claim 24 and further comprising; selectively removing a portion of the first layer overlying the contact pad to expose a portion of the contact pad.
Claim 30
Dependent Claim
47 words
The method of claim 25 and further comprising: covering the exposed portion of the contact pad with a liftoff medium prior to forming the second layer; and removing the liftoff medium and a portion of the second layer overlying the liftoff medium to expose the contact pad.
References Cited (Backward Citations)
GB674484A
Cited
US2802925A
Cited
GB768117A
Cited
US3564474A
Cited
US3714702A
Cited
US4103275A
Cited
US4222025A
Cited
US4050052A
Cited
US4129848A
Cited
US4072593A
Cited
US4139833A
Cited
US4282507A
Cited
US4447824A
Cited
GB2096645A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-12-13 | 1992-06-13 | 1992-12-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-12-13 | 1996-06-13 | 1996-12-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-12-13 | 2000-06-13 | 2000-12-13 | $7700.00 | Window Closed / Lapsed |