US3820401A
Expired / Lapsed
US
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Piezoresistive bridge transducer
Assignee: Unisys Corp
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Filing: 1972-11-07
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Granted: 1974-06-28
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Expires: 1992-11-07
Abstract
Abstract A temperature stable piezoresistor bridge is diffused into the surface of a pressure sensing semiconductor diaphragm formed integrally with a semiconductor body, the diaphragm and body together defining a cavity within the miniature unitary pressureresponsive transducer. Diffused isolation fields and diffused resistors generated at the surfaces of the fields form the piezoresistor bridge on a first semiconductor wafer having a given crystallographic orientation, which structure is then provided with electrically isolated conductors. The first wafer is then bonded to a second wafer of similar material and similar crystallographic orientation for fully defining the cavity element.
Inventors
- 👤 E Lewis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 08:20
CPC Classifications
G; G01; G01L; G01L9/00; G01L9/0041; G01L9/0051; G01L9/0052; G01L9/0054; G01L9/0042; H; H10; H10D; H10D48/00; H10D48/50
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
122 words
Transducer means comprising: first and second bodies of type p conductivity semiconductor material thermally bonded together at a common interface by permanent eutectic metal layer means for providing a unitary body, sealed cavity means within said unitary body at said common interface for forming in said first body diaphragm flexure means at an exterior surface of said first body substantially parallel to said common interface. a diffused type n conductivity semiconductor region within said diaphragm flexure means at said exterior surface, a diffused type p conductivity semiconductor region within said type n conductivity semiconductor region at said exterior surface, and first and second electrical conducor means discretely coupled at spaced points respectively to said diffused type n and p conductivity semiconductor regions.
Claim 2
Dependent Claim
122 words
Transducer means comprising: first and second bodies of type p conductivity semiconductor material thermally bonded together at a common interface by permanent eutectic metal layer means for providing a unitary body, sealed cavity means within said unitary body at said common interface for forming in said first body diaphragm flexure means at an exterior surface of said first body substantially parallel to said common interface. a diffused type n conductivity semiconductor region within said diaphragm flexure means at said exterior surface, a diffused type p conductivity semiconductor region within said type n conductivity semiconductor region at said exterior surface, and first and second electrical conducor means discretely coupled at spaced points respectively to said diffused type n and p conductivity semiconductor regions.
Claim 3
Dependent Claim
32 words
Apparatus as described in claim 1 wherein said common interface lies in a plane substantially parallel to the (111 ) crystallographic direction of the semiconductive material comprising said first and second bodies.
Claim 4
Dependent Claim
24 words
Apparatus as described in claim 2 wherein the semiconductor material of said first and second bodies has a resistivity of substantially 10 ohm centimeters.
Claim 5
Dependent Claim
28 words
Apparatus as described in claim 1 wherein said sealed cavity means comprises a substantially evacuated right circular cylinder having substantially flat ends substantially parallel to said common interface.
Claim 6
Dependent Claim
19 words
Apparatus as described in claim 1 wherein said diffused type n conductivity semiconductor region comprises silicon doped with phosphorous.
Claim 7
Dependent Claim
29 words
Apparatus as described in claim 5 wherein said diffused type p conductivity semiconductor region comprises silicon doped with boron and demonstrates piezoresistivity when said diaphragm flexure means is flexed.
Claim 8
Dependent Claim
38 words
Apparatus as described in claim 1 wherein said exterior surface is substantially covered with a protective layer of silicon oxynitride except where said electrical conductor means couple to said respective diffused type n and p conductivity semiconductor regions.
Claim 9
Dependent Claim
20 words
Apparatus as described in claim 7 wherein said electrical conductor means lie in bonded relation over said silicon oxynitride layer.
Claim 10
Dependent Claim
27 words
Apparatus as described in claim 1 wherein: first, second, and third spaced diffused type n conductivity semiconductor regions lie within said diaphragm means at said exterior surface.
Claim 11
Dependent Claim
55 words
Apparatus as described in claim 9 wherein: first and second diffused type p conductivity semiconductor regions lie within said first type n conductivity semiconducTor region at said exterior surface, and third and fourth diffused type p conductivity semiconductor regions lie within said respective second and third type n conductivity semiconductor regions at said exterior surface.
Claim 12
Dependent Claim
37 words
Apparatus as described in claim 10 wherein: said first electrical conductor means form with said first, second, third, and fourth diffused type p conductivity semiconductor regions piezoresistor bridge means for detecting displacement of said diaphragm flexure means.
Claim 13
Dependent Claim
38 words
Apparatus as described in claim 11 wherein: said second electrical conductor means form bias voltage coupling means for coupling a bias voltage between at least one of said diffused type n conductivity semiconductor regions and said piezoresistor bridge.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-27 | 1977-12-27 | 1978-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-27 | 1981-12-27 | 1982-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-27 | 1985-12-27 | 1986-06-28 | $7700.00 | Window Closed / Lapsed |