Patent US4006045A successfully refreshed from Google Patents.
US4006045A
Expired / Lapsed
US
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Method for producing high power semiconductor device using anodic treatment and enhanced diffusion
Assignee: International Business Machines Corp
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Filing: 1976-02-13
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Granted: 1977-02-01
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Expires: 1996-02-13
Abstract
Abstract A high power semiconductor device is formed by providing a semiconductor substrate of N - conductivity, rendering the backside of same porous as by subjecting same to anodic treatment carried out in a concentrated solution of hydrofluoric acid, converting the porous region to an N + region, as by arsenic diffusion and forming an active device by conventional techniques in the top surface of the substrate. The method permits usage of high quality N - substrates and at the same time eliminates the requirement of growing thick epitaxial layers.
Inventors
- 👤 Joseph A. Aboaf
- 👤 Robert W. Broadie
- 👤 Edward M. Hull
- 👤 H. Bernhard Pogge
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 12:52
CPC Classifications
H; H10; H10D; H10D62/00; H10D62/10; H10D62/13; H10D62/137; H10D62/40; H10P; H10P32/00; H10P32/10; H10P32/12; H10P32/17; H10P32/171; H10P50/00; Y; Y10; Y10S; Y10S438/00; Y10S438/928; Y10S438/96
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
99 words
In the method of producing a semiconductor device, the steps comprising: providing a semiconductor substrate having a top and back surface; forming a porous portion by anodic treatment within said substrate extending inwardly of said back surface; forming a protective insulating layer on the top surface of said substrate; doping said porous portion to a region o higher conductivity than said substrate; forming a protective layer on the back surface of said substrate; removing the top protective insulating layer from said substrate; and, introducing impurities into the top surface of said substrate so as to form a semiconductor device.
Claim 2
Dependent Claim
99 words
In the method of producing a semiconductor device, the steps comprising: providing a semiconductor substrate having a top and back surface; forming a porous portion by anodic treatment within said substrate extending inwardly of said back surface; forming a protective insulating layer on the top surface of said substrate; doping said porous portion to a region o higher conductivity than said substrate; forming a protective layer on the back surface of said substrate; removing the top protective insulating layer from said substrate; and, introducing impurities into the top surface of said substrate so as to form a semiconductor device.
Claim 3
Dependent Claim
24 words
The invention by claim 1 wherein said substrate portion is rendered porous by anodic treatment carried out in a concentrated solution of hydrofluoric acid.
Claim 4
Dependent Claim
27 words
The invention defined by claim 1 wherein silicon dioxide is pyrolytically deposited on the top surface of said substrate to form said top surface protective insulating layer.
Claim 5
Dependent Claim
30 words
The invention defined by claim 1 wherein said porous portion is converted to a region of higher conductivity by diffusing an impurity into said porous portion through said back surface.
Claim 6
Dependent Claim
25 words
The invention defined by claim 1 wherein a polycrystalline silicon layer is deposited over the back surface of said substrate to form a protective layer.
Claim 7
Dependent Claim
24 words
The invention defined by claim 1 wherein said substrate is of N - conductivity and said region of higher conductivity is N + .
Claim 8
Dependent Claim
42 words
The invention defined in claim 1 including forming a porous portion within said substrate extending inwardly of said back surface such that said porous portion includes void areas on the order of 15% as measured by weight loss in said porous portion.
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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) | 1980-02-01 | 1980-08-02 | 1981-02-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-02-01 | 1984-08-02 | 1985-02-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-02-01 | 1988-08-02 | 1989-02-01 | $7700.00 | Window Closed / Lapsed |