Patent US5485025A successfully refreshed from Google Patents.
US5485025A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Depleted extrinsic emitter of collector-up heterojunction bipolar transistor
Assignee: Intel Corp
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Filing: 1994-12-02
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Granted: 1996-01-16
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Expires: 2014-12-02
Abstract
Abstract A collector-up bipolar transistor having an undercut region (522) beneath extrinsic regions of a base layer (510) and an emitter layer (508). The extrinsic emitter region is depleted of charge carriers and provides passivation for the extrinsic portion of the base layer (508). Contact to the emitter layer may be made by forming contacts on the top surface of the substrate (500) or in a recess in the backside of the substrate.
Inventors
- 👤 Hin F. Chau
- 👤 Hua Q. Tserng
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:56
CPC Classifications
H; H10; H10D; H10D10/00; H10D10/80; H10D10/821; Y; Y10; Y10S; Y10S148/00; Y10S148/01; Y10S148/011; Y10S148/072
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
42 words
A bipolar transistor, comprising: a collector layer over a base layer, said base layer over an emitter layer, and said emitter layer over an emitter cap layer, wherein said base and emitter layers extend beyond an edge of said emitter cap layer.
Claim 2
Dependent Claim
42 words
A bipolar transistor, comprising: a collector layer over a base layer, said base layer over an emitter layer, and said emitter layer over an emitter cap layer, wherein said base and emitter layers extend beyond an edge of said emitter cap layer.
Claim 3
Dependent Claim
44 words
The transistor of claim 1, wherein a portion of said emitter layer extending beyond said edge has a thickness less than approximately 0.1 μm and a doping concentration less than approximately 2×10 17 cm -3 , where said portion is depleted of charge carriers.
Claim 4
Dependent Claim
29 words
The transistor of claim 1, further comprising an emitter contact layer beneath said emitter cap layer, and an emitter contact on a top surface of said emitter contact layer.
Claim 5
Dependent Claim
24 words
The transistor of claim 1, further comprising a collector contact layer over said collector layer, and a collector contact on said collector contact layer.
Claim 6
Dependent Claim
15 words
The transistor of claim 1, further comprising an emitter contact beneath said emitter cap layer.
Claim 7
Dependent Claim
87 words
A bipolar transistor, comprising: a structure including an emitter cap layer, an emitter layer, a base layer and a collector layer formed over a substrate, wherein said collector layer lies over said base layer, said base layer lies over said emitter layer, and said emitter layer lies over said emitter cap layer, and further wherein said emitter and base layers extend beyond an edge of said emitter cap layer; a recess in a backside of said substrate beneath said structure; and an emitter contact in said recess.
Claim 8
Dependent Claim
87 words
A bipolar transistor, comprising: a structure including an emitter cap layer, an emitter layer, a base layer and a collector layer formed over a substrate, wherein said collector layer lies over said base layer, said base layer lies over said emitter layer, and said emitter layer lies over said emitter cap layer, and further wherein said emitter and base layers extend beyond an edge of said emitter cap layer; a recess in a backside of said substrate beneath said structure; and an emitter contact in said recess.
Claim 9
Dependent Claim
44 words
The transistor of claim 6, wherein a portion of said emitter layer extending beyond said edge has a thickness less than approximately 0.1 μm and a doping concentration less than approximately 2×10 17 cm -3 , where said portion is depleted of charge carriers.
Claim 10
Dependent Claim
28 words
The transistor of claim 6, further comprising an emitter contact layer beneath said emitter cap layer, and wherein said emitter contact is attached to said emitter contact layer.
Claim 11
Dependent Claim
27 words
The transistor of claim 8, further comprising a layer of metallization covering said emitter contact, said recess, and a portion of said backside surface of said substrate.
Claim 12
Dependent Claim
21 words
The transistor of claim 6, further comprising a base contact on a portion of said base layer extending beyond said edge.
Claim 13
Dependent Claim
24 words
The transistor of claim 6, further comprising a collector contact layer over said collector layer, and a collector contact on said collector contact layer.
Claim 14
Dependent Claim
17 words
The transistor of claim 6, wherein said base layer comprises GaAs and said emitter layer comprises AlGaAs.
Claim 15
Dependent Claim
24 words
The transistor of claim 6, further comprising a layer of dielectric covering portions of said base contact, said collector contact, and said collector layer.
Claim 16
Dependent Claim
16 words
The transistor of claim 9, further comprising a heatsink in contact with said layer of metallization.
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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) | 1999-01-15 | 1999-07-17 | 2000-01-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-01-15 | 2003-07-17 | 2004-01-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-01-15 | 2007-07-17 | 2008-01-16 | $7700.00 | Window Closed / Lapsed |