US5619476A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrostatic ultrasonic transducer
Assignee: Leland Stanford Junior University
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Filing: 1994-10-21
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Granted: 1997-04-08
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Expires: 2014-10-21
Abstract
Abstract An electrostatic ultrasonic transducer formed on a semiconductor substrate by micro-machining wherein the transducer includes a silicon nitride membrane supported above the surface of the substrate by insulating supports; and the substrate and membrane define the electrodes of the transducer.
Inventors
- 👤 Matthew I. Haller
- 👤 Butrus T. Khuri-Yakub
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:31
CPC Classifications
B; B06; B06B; B06B1/00; B06B1/02; B06B1/0292; B06B1/06; B06B1/0688; B06B1/0696; H; H02; H02N; H02N1/00; H02N1/002; H02N1/006
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
135 words
An ultrasonic transducer which includes: a substrate having first and second major surfaces; a layer of insulator material having a plurality of void regions and support regions formed on one major surface of said substrate; a layer of silicon nitride having residual stress formed on and supported by said layer of insulator material and extending over said void regions spaced from said one major surface of said substrate to form a membrane capable of vibrating at each of said void regions, said silicon nitride layer including openings communicating with each of said void regions; a thin conductive film formed on an outer surface of said silicon nitride layer and a thin conductive film formed on a major surface of said substrate whereby to form a plurality of transducers one at each of said void regions.
Claim 2
Dependent Claim
135 words
An ultrasonic transducer which includes: a substrate having first and second major surfaces; a layer of insulator material having a plurality of void regions and support regions formed on one major surface of said substrate; a layer of silicon nitride having residual stress formed on and supported by said layer of insulator material and extending over said void regions spaced from said one major surface of said substrate to form a membrane capable of vibrating at each of said void regions, said silicon nitride layer including openings communicating with each of said void regions; a thin conductive film formed on an outer surface of said silicon nitride layer and a thin conductive film formed on a major surface of said substrate whereby to form a plurality of transducers one at each of said void regions.
Claim 3
Dependent Claim
24 words
An electrostatic ultrasonic transducer as in claim 1 wherein said substrate is highly doped silicon and said layer of insulator material is silicon oxide.
Claim 4
Dependent Claim
24 words
An electrostatic ultrasonic transducer as in claim 1 wherein said substrate is highly doped silicon, and said layer of insulator material is silicon nitride.
Claim 5
Dependent Claim
13 words
An electrostatic ultrasonic transducer as in claim 1 wherein said membrane is circular.
Claim 6
Dependent Claim
13 words
An electrostatic ultrasonic transducer as in claim 1 wherein the membrane is rectangular.
Claim 7
Dependent Claim
12 words
An ultrasonic transducer as in claim 1 wherein said substrate is silicon.
Claim 8
Dependent Claim
18 words
An ultrasonic transducer as in claim 1 wherein the surface of said substrate at said voids is rough.
Claim 9
Dependent Claim
16 words
An ultrasonic transducer as in claim 1 wherein said layer of insulator material is silicon nitride.
Claim 10
Dependent Claim
13 words
An ultrasonic transducer as in claim 1 wherein said layer of insulator material.
Claim 11
Dependent Claim
23 words
An ultrasonic transducer as in claim 9 wherein said substrate comprises an insulator with a conductive layer facing said layer of insulator material.
Claim 12
Dependent Claim
34 words
An ultrasonic transducer as in claim 1 wherein the layer of silicon nitride has a thickness of about 7500Å and the layer of insulator material is silicon oxide having a thickness of about 10,000Å.
Claim 13
Dependent Claim
19 words
An ultrasonic transducer as in claim 11 wherein the silicon nitride has a residual stress of about 280 MPas.
Claim 14
Dependent Claim
21 words
An ultrasonic transducer as in claim 1 in which the openings in the nitride layer are approximately 3 μm in diameter.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-04-07 | 2000-10-07 | 2001-04-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-04-07 | 2004-10-07 | 2005-04-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-04-07 | 2008-10-07 | 2009-04-08 | $7700.00 | Window Closed / Lapsed |