US4525239A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Extrinsic gettering of GaAs wafers for MESFETS and integrated circuits
Assignee: HP Inc
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Filing: 1984-04-23
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Granted: 1985-06-25
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Expires: 2004-04-23
Abstract
Abstract A method is disclosed for extrinsically gettering imperfections in a semi-insulating GaAs wafer. This is accomplished by subjecting the semi-insulating GaAs wafers to processing conditions which allow the imperfections to migrate toward a mechanically damaged surface region of the wafer. Migration occurs during a low temperature heat treatment over an extended time period. The GaAs wafer surface is damaged by a bead blasting treatment and subsequently heated to a temperature in the range of 400 to 600 degrees Celsius in a forming gas for a period between 12 to 120 hours. Significant improvements of the GaAs wafer qualities and performance of fabricated MESFET devices are achieved.
Inventors
- 👤 Faa-Ching Wang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 20:00
CPC Classifications
H; H10; H10P; H10P95/00; H10P95/40; H10P95/408; H10P95/90; H10P95/904
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
100 words
A method for isolating imperfections in a GaAs wafer having first and second surfaces, comprising the steps of: forming an insulating layer over the first and second surfaces; mechanically treating one of the first and second surfaces to produce a surface damage layer; heating said substrate in a forming gas to a temperature no higher than a temperature required to maintain the substrate at a semi-insulating condition; maintaining said temperature over a period of time sufficient for the imperfections to migrate in the substrate toward said damaged surface layer; and removing said insulating layer over said surface not mechanically damaged.
Claim 2
Independent Claim
100 words
A method for isolating imperfections in a GaAs wafer having first and second surfaces, comprising the steps of: forming an insulating layer over the first and second surfaces; mechanically treating one of the first and second surfaces to produce a surface damage layer; heating said substrate in a forming gas to a temperature no higher than a temperature required to maintain the substrate at a semi-insulating condition; maintaining said temperature over a period of time sufficient for the imperfections to migrate in the substrate toward said damaged surface layer; and removing said insulating layer over said surface not mechanically damaged.
Claim 3
Dependent Claim
13 words
A method as in claim 1 wherein said insulating layer comprises silicon dioxide.
Claim 4
Dependent Claim
13 words
A method as in claim 1 wherein said mechanical treating comprises bead blasting.
Claim 5
Dependent Claim
19 words
A method as in claim 3 wherein said temperature is in the range of 400 to 600 degrees Celsius.
Claim 6
Dependent Claim
18 words
A method as in claim 4 wherein said period is in the range of 12 to 120 hours.
Claim 7
Dependent Claim
16 words
A method as in claim 1 further comprising the step of: removing said damaged surface layer.
Claim 8
Dependent Claim
17 words
A method as in claim 6 wherein the step of removing said damaged surface comprises mechanical lapping.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-06-24 | 1988-12-24 | 1989-06-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-06-24 | 1992-12-24 | 1993-06-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-06-24 | 1996-12-24 | 1997-06-25 | $7700.00 | Window Closed / Lapsed |