US5344786A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of fabricating self-aligned heterojunction bipolar transistors
Assignee: Texas Instruments Inc
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Filing: 1992-09-09
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Granted: 1994-09-06
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Expires: 2012-09-09
Abstract
Abstract A method of fabricating heterojunction bipolar transistors (HBTs) including epitaxial growth of collector, base and emitter layers, allowing for self-aligned emitter-base contacts to minimize series base resistance and to reduce total base-collector capacitance.
Inventors
- 👤 Burhan Bayraktaroglu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 12:31
CPC Classifications
H; H10; H10D; H10D84/00; H10D10/00; H10D10/01; H10D10/021; H10D64/00; H10D64/01; H10D64/011; H10D62/00; H10D62/80; H10D62/85; Y; Y10; Y10S; Y10S148/00; Y10S148/072
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
174 words
A method of fabricating a heterojunction bipolar transistor, comprising the steps of: (a) forming a collector layer over a semi-insulating semiconductor substrate; (b) forming a base layer over said collector layer; (c) forming an emitter layer over said base layer; (d) forming an ohmic emitter contact layer over said emitter layer; (e) forming an insulator layer over said ohmic emitter contact layer; (f) removing said insulator layer and said ohmic emitter contact layer from all areas not covering an emitter location; (g) forming insulator sidewalls abutting vertical surfaces of said insulator layer and said ohmic emitter contact layer, said insulator sidewalls also abutting a portion of a horizontal surface of said emitter layer; (h) removing said emitter layer from all areas not covered by said insulator layer or by said insulator sidewalls; and (i) forming an ohmic base contact layer to be horizontally continuous over said insulator layer, said insulator sidewalls and a portion of said base layer, and to be vertically discontinuous between said insulator sidewalls and said portion of said base layer.
Claim 2
Independent Claim
174 words
A method of fabricating a heterojunction bipolar transistor, comprising the steps of: (a) forming a collector layer over a semi-insulating semiconductor substrate; (b) forming a base layer over said collector layer; (c) forming an emitter layer over said base layer; (d) forming an ohmic emitter contact layer over said emitter layer; (e) forming an insulator layer over said ohmic emitter contact layer; (f) removing said insulator layer and said ohmic emitter contact layer from all areas not covering an emitter location; (g) forming insulator sidewalls abutting vertical surfaces of said insulator layer and said ohmic emitter contact layer, said insulator sidewalls also abutting a portion of a horizontal surface of said emitter layer; (h) removing said emitter layer from all areas not covered by said insulator layer or by said insulator sidewalls; and (i) forming an ohmic base contact layer to be horizontally continuous over said insulator layer, said insulator sidewalls and a portion of said base layer, and to be vertically discontinuous between said insulator sidewalls and said portion of said base layer.
Claim 3
Dependent Claim
34 words
The heterojunction bipolar transistor device fabrication method of claim 1, comprising the further step of: (a) forming said emitter layer with a semiconductor material with a wider bandgap than said base layer semiconductor material.
Claim 4
Dependent Claim
34 words
The heterojunction bipolar transistor device fabrication method of claim 1, comprising the further step of: (a) forming said emitter layer with a semiconductor material with a wider bandgap than said collector layer semiconductor material.
Claim 5
Dependent Claim
45 words
The heterojunction bipolar transistor device fabrication method of claim 1, comprising the further steps of: (a) forming said collector layer with GaAs on a GaAs substrate; (b) forming said base layer with GaAs; and (c) forming said emitter layer with Al x Ga 1-x As.
Claim 6
Dependent Claim
34 words
The heterojunction bipolar transistor device fabrication method of claim 4, comprising the further steps of: (a) doping said collector layer n-type; (b) doping said base layer p-type; and (c) doping said emitter layer n-type.
Claim 7
Dependent Claim
23 words
The heterojunction bipolar transistor device fabrication method of claim 1, comprising the further step of: (a) forming said emitter contact layer with AuGe/Ni/Au.
Claim 8
Dependent Claim
29 words
The heterojunction bipolar transistor device fabrication method of claim 1, comprising the further step of: (a) forming said emitter layer by epitaxial growth of in situ doped semiconductor material.
Claim 9
Dependent Claim
27 words
The heterojunction bipolar transistor device fabrication method of claim 1, comprising the further step of: (a) forming a metal ion mill mask layer on said insulator layer.
Claim 10
Dependent Claim
24 words
The heterojunction bipolar transistor device fabrication method of claim 8, comprising the further step of: (a) forming said metal ion mask layer with Ti.
Claim 11
Dependent Claim
34 words
The heterojunction bipolar transistor device fabrication method of claim 8, including the further step of: (a) removing said metal ion mill mask from regions not in an active area of said heterojunction bipolar transistor.
Claim 12
Dependent Claim
33 words
The heterojunction bipolar transistor device fabrication method of claim 1, further including the step of: (a) forming non-conductive regions by ion implantation in areas of said collector layer not beneath an emitter region.
Claim 13
Dependent Claim
29 words
The heterojunction bipolar transistor device fabrication method of claim 1, comprising the further step of: (a) forming said base layer by epitaxial growth of in situ doped semiconductor material.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1997-09-05 | 1998-03-07 | 1998-09-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-09-05 | 2002-03-07 | 2002-09-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-09-05 | 2006-03-07 | 2006-09-06 | $7700.00 | Window Closed / Lapsed |