US4426656A
Expired / Lapsed
US
⏱️ 0.0 years remaining
GaAs FETs Having long-term stability
Assignee: AT&T Inc
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Filing: 1981-01-29
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Granted: 1984-01-17
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Expires: 2001-01-29
Abstract
Abstract GaAs FETs exhibit excellent long-term stability if they have a drain ledge, a drain contact with reduced dendrite size, and a silicon nitride passivation layer. Accelerated aging tests at device case temperatures of 250 degrees C. indicate essentially no device failures after 200 hours of observation and a median failure time of approximately 500 hours.
Inventors
- 👤 James V. DiLorenzo
- 👤 James C. Hwang
- 👤 William C. Niehaus
- 👤 Wolfgang O. W. Schlosser
- 👤 Stuart H. Wemple
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 22:30
CPC Classifications
H; H10; H10W; H10W74/00; H10W74/10; H10W74/131; H10W74/137; H10D; H10D30/00; H10D30/80; H10D30/87; H10D62/00; H10D62/10; H10D62/13; H10D62/149; H10W74/40; H10W74/43; H10P; H10P14/00; H10P14/60; H10P14/63; H10P14/6326; H10P14/6328; H10P14/6334; H10P14/6336; H10P14/66; H10P14/668; H10P14/6681; H10P14/6682; H10P14/69; H10P14/694; H10P14/6943; H10P14/69433
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
86 words
In a field effect transistor device comprising an active region of GaAs, a source, a gate, and a drain wherein said drain comprises a drain ledge contacting said active region and an electrical contact to said drain ledge CHARACTERIZED IN THAT said device is passivated with a material that prevents oxidation of said active region, said ledge extends beyond the edge of said contact in the direction of said gate, and dendrites formed during the fabrication of said contact terminate with the boundaries of said ledge.
Claim 2
Dependent Claim
86 words
In a field effect transistor device comprising an active region of GaAs, a source, a gate, and a drain wherein said drain comprises a drain ledge contacting said active region and an electrical contact to said drain ledge CHARACTERIZED IN THAT said device is passivated with a material that prevents oxidation of said active region, said ledge extends beyond the edge of said contact in the direction of said gate, and dendrites formed during the fabrication of said contact terminate with the boundaries of said ledge.
Claim 3
Dependent Claim
32 words
The device of either claim 1 wherein the extension of said ledge beyond said contact is at least equal to the thickness of said active region at a point below said gate.
Claim 4
Dependent Claim
13 words
The device of either claim 1 wherein said passivating material comprises silicon nitride.
Claim 5
Dependent Claim
10 words
The device of claim 3 wherein silicon nitride contains hydrogen.
Claim 6
Dependent Claim
22 words
The device of claim 4 where said silicon nitride is formed by striking a plasma in an environment comprising ammonia and silane.
Claim 7
Dependent Claim
19 words
The device of claim 5 wherein the ratio of ammonia to silane is in the range 1.62 to 2.05.
References Cited (Backward Citations)
US4196439A
Cited
US4301188A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-01-16 | 1987-07-18 | 1988-01-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-01-16 | 1991-07-18 | 1992-01-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-01-16 | 1995-07-18 | 1996-01-17 | $7700.00 | Window Closed / Lapsed |