Patent US3065188A successfully refreshed from Google Patents.
Patent US5350699A successfully refreshed from Google Patents.
US5350699A
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US
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Method of manufacturing a hetero-junction bi-polar transistor
Assignee: Rohm Co Ltd
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Filing: 1993-05-11
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Granted: 1994-09-27
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Expires: 2013-05-11
Abstract
Abstract A hetero-junction bi-polar transistor provided with a collector composed of a β - SiC substrate and a base area composed of a β - SiC layer and an emitter area composed of an α - SiC layer, thereby forming a hetero-junction bi-polar transistor having superior heat resistance.
Inventors
- 👤 Keita Nii
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 16:54
CPC Classifications
H; H10; H10D; H10D10/00; H10D10/01; H10D10/021; H10D10/80; H10D10/821; H10D10/861; H10D12/00; H10D12/01; H10D12/031; H10D62/00; H10D62/80; H10D62/83; H10D62/832; H10D62/8325; Y; Y10; Y10S; Y10S148/00; Y10S148/148; Y10S438/00; Y10S438/931
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
207 words
A method of manufacturing a hetero-junction bipolar transistor comprising the steps of: A) forming a beta silicon carbide layer of a first type of conductivity on a top face of a beta silicon carbide substrate of a second type of conductivity which is opposite of that of the first type of conductivity, the beta silicon carbide layer of the first type of conductivity forming a base area of the transistor and the beta silicon carbide substrate of the second type of conductivity forming the collector of the transistor; B) forming an alpha silicon carbide layer of the second type of conductivity on the beta silicon carbide layer of the first type of conductivity, the alpha silicon carbide layer of the second type of conductivity forming the emitter of the transistor; C) selectively removing a portion of the alpha silicon carbide layer of the second type of conductivity to expose a portion of the beta silicon carbide layer of the first type of conductivity; and D) respectively forming collector, base, and emitter electrodes on the beta silicon carbide substrate of the second type of conductivity, the beta silicon carbide layer of the first type of conductivity and the alpha silicon carbide layer of the second type of conductivity.
Claim 2
Independent Claim
207 words
A method of manufacturing a hetero-junction bipolar transistor comprising the steps of: A) forming a beta silicon carbide layer of a first type of conductivity on a top face of a beta silicon carbide substrate of a second type of conductivity which is opposite of that of the first type of conductivity, the beta silicon carbide layer of the first type of conductivity forming a base area of the transistor and the beta silicon carbide substrate of the second type of conductivity forming the collector of the transistor; B) forming an alpha silicon carbide layer of the second type of conductivity on the beta silicon carbide layer of the first type of conductivity, the alpha silicon carbide layer of the second type of conductivity forming the emitter of the transistor; C) selectively removing a portion of the alpha silicon carbide layer of the second type of conductivity to expose a portion of the beta silicon carbide layer of the first type of conductivity; and D) respectively forming collector, base, and emitter electrodes on the beta silicon carbide substrate of the second type of conductivity, the beta silicon carbide layer of the first type of conductivity and the alpha silicon carbide layer of the second type of conductivity.
Claim 3
Dependent Claim
31 words
A method as recited in claim 1, wherein the first type of conductivity is a P type of conductivity and the second type of conductivity is an N type of conductivity.
Claim 4
Dependent Claim
21 words
A method as recited in claim 2, wherein the beta silicon carbide layer in Step A is formed by ion implantation.
Claim 5
Dependent Claim
15 words
A method as recited in claim 3, wherein boron ions are injected by ion implantation.
Claim 6
Dependent Claim
22 words
A method as recited in claim 2, wherein the alpha silicon carbide layer in step B is formed by an RF-CVD method.
Claim 7
Dependent Claim
17 words
A method as recited in claim 5, wherein a phosphorus dopant is used in the RF-CVD method.
Claim 8
Dependent Claim
48 words
A method as recited in claim 6, wherein the alpha silicon carbide layer is grown to a thickness on the order of 0.2 micrometers using a 1200° C. basic plate temperature and a reaction gas composition of SiH 4 (0.15 sccm) and C 3 H 8 (0.2 sccm).
Claim 9
Dependent Claim
26 words
A method as recited in claim 2, wherein the portion of the alpha silicon carbide layer is removed in step C by a plasma etching method.
Claim 10
Dependent Claim
39 words
A method as recited in claim 8, wherein plasma etching is effected at an RF power of 200 watts and a pressure of 0.005 Torr and a reaction gas composition of 50% O 2 and 50% CF 4 .
Claim 11
Dependent Claim
21 words
A method as recited in claim 1, wherein the beta silicon carbide layer in Step A is formed by ion implantation.
Claim 12
Dependent Claim
22 words
A method as recited in claim 1, wherein the alpha silicon carbide layer in step B is formed by an RF-CVD method.
Claim 13
Dependent Claim
26 words
A method as recited in claim 1, wherein the portion of the alpha silicon carbide layer is removed in step C by a plasma etching method.
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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) | 1997-09-26 | 1998-03-28 | 1998-09-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-09-26 | 2002-03-28 | 2002-09-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-09-26 | 2006-03-28 | 2006-09-27 | $7700.00 | Window Closed / Lapsed |