Patent EP0311419A2 successfully refreshed from Google Patents.
Patent US5672522A successfully refreshed from Google Patents.
US5672522A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for making selective subcollector heterojunction bipolar transistors
Assignee: Northrop Grumman Systems Corp
•
Filing: 1996-03-05
•
Granted: 1997-09-30
•
Expires: 2016-03-05
Abstract
Abstract A method for fabricating an HBT in which the subcollector-base junction, which contributes to the base-collector capacitance of the device, is reduced by using a selective subcollector. In particular, subcollector areas of the device that do not contribute to collector resistance reduction are eliminated, thereby reducing the subcollector area, which, in turn, reduces the base-collector capacitance. As such, the maximum power-gain frequency f max is increased.
Inventors
- 👤 Dwight Christopher Streit
- 👤 Michael Lammert
- 👤 Aaron Kenji Oki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 04:14
CPC Classifications
H; H10; H10P; H10P30/00; H10P30/20; H10P30/21; H10D; H10D10/00; H10D10/01; H10D10/021; H10D10/80; H10D10/821; H10P30/202; H10P30/206; H10W; H10W15/00; H10W15/01; H10D62/00; H10D62/80; H10D62/85; Y; Y10; Y10S; Y10S148/00; Y10S148/01; Y10S148/011; Y10S148/072
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
74 words
A method for fabricating a heterojunction bipolar transistor (HBT) with an increased maximum power gain frequency, comprising the steps of: (a) providing a substrate; (b) patterning a photo-resist over a portion of said substrate; (c) implanting silicon ions in a portion of said substrate not covered by said photo-resist, forming a subcollector; (d) forming collector, base and emitter regions over said subcollector; and (e) forming ohmic contacts on said collector, base and emitter regions.
Claim 2
Independent Claim
74 words
A method for fabricating a heterojunction bipolar transistor (HBT) with an increased maximum power gain frequency, comprising the steps of: (a) providing a substrate; (b) patterning a photo-resist over a portion of said substrate; (c) implanting silicon ions in a portion of said substrate not covered by said photo-resist, forming a subcollector; (d) forming collector, base and emitter regions over said subcollector; and (e) forming ohmic contacts on said collector, base and emitter regions.
Claim 3
Dependent Claim
12 words
A method as recited in claim 1, wherein said substrate is GaAs.
Claim 4
Dependent Claim
22 words
A method as recited in claim 1, wherein an acceleration energy of about 50 keV or greater is used for silicon-ion implantation.
Claim 5
Dependent Claim
19 words
A method as recited in claim 1, wherein a plurality of acceleration energies are used for said silicon-ion implantation.
Claim 6
Dependent Claim
21 words
A method as recited in claim 4, wherein each of said plurality of acceleration energies is greater than about 50 keV.
Claim 7
Dependent Claim
21 words
A method as recited in claim 4, wherein said plurality of acceleration energies vary about 50 keV to about 260 keV.
Claim 8
Dependent Claim
15 words
A method as recited in claim 1, wherein said subcollector is an N+ type material.
References Cited (Backward Citations)
US3780359A
Cited
US4081292A
Cited
US4029522A
Cited
US4789643A
Cited
US4975126A
Cited
US4967253A
Cited
US5064772A
Cited
US4954457A
Cited
US5098853A
Cited
US5041393A
Cited
US5028549A
Cited
US5283448A
Cited
US5070028A
Cited
US5252143A
Cited
US5243207A
Cited
US5336909A
Cited
US5162243A
Cited
US5286997A
Cited
US5298438A
Cited
US5242843A
Cited
US5362657A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-09-29 | 2001-03-31 | 2001-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-09-29 | 2005-03-31 | 2005-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-09-29 | 2009-03-31 | 2009-09-30 | $7700.00 | Window Closed / Lapsed |