Patent US3970487A successfully refreshed from Google Patents.
US3970487A
Expired / Lapsed
US
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Method of manufacturing a power transistor
Assignee: International Business Machines Corp
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Filing: 1975-06-16
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Granted: 1976-07-20
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Expires: 1995-06-16
Abstract
Abstract A method for manufacturing a power transistor having a highly doped emitter zone and a narrow base zone with a flat doping profile. In a long-term diffusion step ensuring the flat doping profile, the base zone is diffused into a lowly doped substrate serving as a collector. In a subsequent etching process, the base zone is etched down to a shell-shaped remainder. A large area, highly doped emitter zone with a steep doping profile and thus a high emitter efficiency is introduced into this shell-shaped remainder in a short-term diffusion step.
Inventors
- 👤 Manfred Dahmen
- 👤 Anneliese Ritzhaupt
- 👤 Manfred Zurheide
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 19:49
CPC Classifications
H; H10; H10P; H10P10/00; H10D; H10D99/00; H10P95/00; Y; Y10; Y10S; Y10S148/00; Y10S148/05; Y10S148/051; Y10S148/139; Y10S148/145
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
87 words
The method of manufacturing a planar power transistor having a highly doped emitter zone, a base zone with a flat doping profile, and a collector zone in a first conductivity type substrate, wherein the improvement comprises: forming said base zone by introducing a second opposite conductivity type impurity into said substrate, etching said base zone down to a shell-shaped remainder, forming said highly doped emitter zone by introducing first conductivity type impurity into said base zone remainder and forming contacts to the individual zones of said transistor.
Claim 2
Independent Claim
87 words
The method of manufacturing a planar power transistor having a highly doped emitter zone, a base zone with a flat doping profile, and a collector zone in a first conductivity type substrate, wherein the improvement comprises: forming said base zone by introducing a second opposite conductivity type impurity into said substrate, etching said base zone down to a shell-shaped remainder, forming said highly doped emitter zone by introducing first conductivity type impurity into said base zone remainder and forming contacts to the individual zones of said transistor.
Claim 3
Dependent Claim
15 words
The method in accordance with claim 1, wherein said emitter zone is formed by diffusion.
Claim 4
Dependent Claim
29 words
The method in accordance with claim 2, wherein said base zone is etched using an etching mask and said emitter zone is formed by diffusion using said etching mask.
Claim 5
Dependent Claim
18 words
The method in accordance with claim 1 wherein said base zone is introduced in a long-term diffusion step.
Claim 6
Dependent Claim
17 words
The method in accordance with claim 4, wherein said emitter zone is introduced in a short-term diffusion.
Claim 7
Dependent Claim
29 words
The method in accordance with claim 5, wherein said base zone is etched using an etching mask and said emitter zone is formed by diffusion using said etching mask.
Claim 8
Dependent Claim
30 words
The method in accordance with claim 1, wherein said emitter zone is formed as a multi-emitter structure and the individual emitter areas are jointly connected to a common emitter terminal.
Claim 9
Dependent Claim
20 words
The method in accordance with claim 1, wherein said emitter zone is formed as a continuous screen type emitter zone.
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) | 1979-07-20 | 1980-01-19 | 1980-07-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-07-20 | 1984-01-19 | 1984-07-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-07-20 | 1988-01-19 | 1988-07-20 | $7700.00 | Window Closed / Lapsed |