Patent US5003365A successfully refreshed from Google Patents.
US5003365A
Expired / Lapsed
US
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Bipolar transistor with a sidewall-diffused subcollector
Assignee: Texas Instruments Inc
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Filing: 1990-05-24
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Granted: 1991-03-26
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Expires: 2010-05-24
Abstract
Abstract A bipolar transistor with a subcollector diffused from a trench contact is disclosed. The bipolar transistor is formed by an n-type collector region disposed over a p-type substrate, or over a p-type epitaxial layer disposed over a p+ substrate. A trench is formed surrounding the transistor, with a dielectric layer formed on the sides and bottom of the trench. An opening is formed in the dielectric layer adjacent the collector region; the trench is filled with a dopant source such as heavily doped n-type polysilicon. During the diffusion of the base region from an implant, n-type dopant diffuses out from the filled trench through the opening, to form an n+ subcollector in the collector region. An emitter region, and an extrinsic base region, are then formed to complete the transistor. Additional disclosed embodiments include the use of an isolation structure to fill the trench on the side of the transistor adjacent the extrinsic base, so that collector-to-base capacitance is minimized. Additional disclosed embodiments also include formation of a p-n-p transistor with a similar diffused subcollector, and a transistor having an extrinsic base region similarly formed by diffusion from a filled trench.
Inventors
- 👤 Robert H. Havemann
- 👤 Robert H. Eklund
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 14:01
CPC Classifications
H; H10; H10D; H10D10/00; H10D10/40; H10D62/00; H10D62/10; H10D62/13; H10D62/137; H10P; H10P32/00; H10P32/10; H10P32/14; H10P32/1408; H10P32/1414; H10P32/17; H10P32/171; H10W; H10W20/00; H10W20/01; H10W20/021
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
108 words
A bipolar transistor without a buried collector layer and formed at a surface of a semiconducting body, said transistor comprising: a collector region of a first conductivity type; a base region of a second conductivity type; an emitter region of said first conductivity type; a collector contact formed in a trench extending from said surface to said collector region; a dielectric surrounding said collector contact in said trench, said dielectric having an opening adjacent said collector region; and a subcollector of said first conductivity type directly electrically connecting said collector region to said collector contact through said opening in said dielectric without connection to a buried collector layer.
Claim 2
Dependent Claim
108 words
A bipolar transistor without a buried collector layer and formed at a surface of a semiconducting body, said transistor comprising: a collector region of a first conductivity type; a base region of a second conductivity type; an emitter region of said first conductivity type; a collector contact formed in a trench extending from said surface to said collector region; a dielectric surrounding said collector contact in said trench, said dielectric having an opening adjacent said collector region; and a subcollector of said first conductivity type directly electrically connecting said collector region to said collector contact through said opening in said dielectric without connection to a buried collector layer.
Claim 3
Dependent Claim
18 words
The transistor of claim 1, wherein said collector contact comprises polycrystalline silicon doped to said first conductivity type.
Claim 4
Dependent Claim
64 words
The transistor of claim 1, wherein said collector region comprises a subcollector; wherein said collector region further comprises: a layer of said body doped with dopant of said first conductivity type, and in contact with said subcollector; wherein said base region disposed between said layer of said collector region and said surface; and wherein said layer is relatively lightly doped relative to said subcollector.
Claim 5
Dependent Claim
28 words
The transistor of claim 1, wherein said trench circumscribes a portion of said surface to define a mesa; and wherein said base region is disposed within said mesa.
Claim 6
Dependent Claim
20 words
The transistor of claim 4, wherein said collector contact is disposed in said trench on all sides of said mesa.
Claim 7
Dependent Claim
24 words
The transistor of claim 5, wherein the opening in the dielectric is in contact with the collector region on all sides of said mesa.
Claim 8
Dependent Claim
22 words
The transistor of claim 1, further comprising an extrinsic base region of said second conductivity type in contact with said base region.
Claim 9
Dependent Claim
29 words
The transistor of claim 1, further comprising: an emitter electrode comprising polycrystalline silicon in contact with said emitter region, said emitter electrode having a portion overlying said collector contact.
Claim 10
Dependent Claim
22 words
The transistor of claim 3, further comprising: a buffer layer of said second conductivity type underlying said layer of said collector region.
Claim 11
Dependent Claim
17 words
The transistor of claim 9, wherein the trench containing said collector contact extends to said buffer layer.
Claim 12
Dependent Claim
28 words
The transistor of claim 9, wherein said transistor is formed on a substrate of said first conductivity type, said substrate being more heavily doped than said buffer layer.
Claim 13
Dependent Claim
16 words
The transistor of claim 11, wherein the trench containing said collector contact extends to said substrate.
Claim 14
Dependent Claim
146 words
A bipolar transistor without a buried collector layer and formed at a surface of a semiconducting body, said transistor comprising: a collector region of a first conductivity type; a base region of a second conductivity type having a portion disposed between said collector region and said surface; an extrinsic base region disposed adjacent said base region; an emitter region of said first conductivity type having a portion disposed between said base region and said surface; a collector contact formed in a trench extending from said surface to said collector region; a dielectric surrounding said collector contact in said trench, said dielectric having an opening adjacent said collector region; a subcollector of said first conductivity type in contact with said collector region and said collector contact, and disposed adjacent said opening in said dielectric; and wherein said subcollector region is not directly under said extrinsic base region.
Claim 15
Dependent Claim
146 words
A bipolar transistor without a buried collector layer and formed at a surface of a semiconducting body, said transistor comprising: a collector region of a first conductivity type; a base region of a second conductivity type having a portion disposed between said collector region and said surface; an extrinsic base region disposed adjacent said base region; an emitter region of said first conductivity type having a portion disposed between said base region and said surface; a collector contact formed in a trench extending from said surface to said collector region; a dielectric surrounding said collector contact in said trench, said dielectric having an opening adjacent said collector region; a subcollector of said first conductivity type in contact with said collector region and said collector contact, and disposed adjacent said opening in said dielectric; and wherein said subcollector region is not directly under said extrinsic base region.
Claim 16
Dependent Claim
32 words
The transistor of claim 13, wherein said trench containing said collector contact circumscribes a portion of said surface to define a mesa; and wherein said base region is disposed within said mesa.
Claim 17
Dependent Claim
17 words
The transistor of claim 14, further comprising: an extrinsic base region in contact with said base region.
Claim 18
Dependent Claim
20 words
The transistor of claim 15, wherein said trench containing said collector contact has a portion adjacent said extrinsic base region.
Claim 19
Dependent Claim
32 words
The transistor of claim 16, wherein said trench containing said collector contact circumscribes a portion of said surface to define a mesa; and wherein said base region is disposed within said mesa.
Claim 20
Dependent Claim
20 words
The transistor of claim 16, wherein the portion of said trench adjacent said extrinsic base region contains an isolation structure.
Claim 21
Dependent Claim
12 words
The transistor of claim 18, wherein said isolation structure comprises silicon dioxide.
Claim 22
Dependent Claim
14 words
The transistor of claim 19, wherein said isolation structure further comprises a polysilicon plug.
Claim 23
Dependent Claim
12 words
The transistor of claim 13, wherein said collector contact comprises polycrystalline silicon.
Claim 24
Dependent Claim
14 words
The transistor of claim 21, wherein said collector contact further comprises a refractory metal.
Claim 25
Dependent Claim
11 words
The transistor of claim 22, wherein said refractory metal is tungsten.
Claim 26
Dependent Claim
100 words
A bipolar transistor without a buried collector layer and formed at a surface of a semiconducting body, said transistor comprising: a collector region of a first conductivity type; a base region of a second conductivity type; an emitter region of said first conductivity type; a base contact formed in a trench extending from said surface to said base region; a dielectric surrounding said base contact in said trench, said dielectric having an opening adjacent said base region; and an extrinsic base of said second conductivity type having a portion disposed within said base region adjacent said opening in said dielectric.
Claim 27
Dependent Claim
100 words
A bipolar transistor without a buried collector layer and formed at a surface of a semiconducting body, said transistor comprising: a collector region of a first conductivity type; a base region of a second conductivity type; an emitter region of said first conductivity type; a base contact formed in a trench extending from said surface to said base region; a dielectric surrounding said base contact in said trench, said dielectric having an opening adjacent said base region; and an extrinsic base of said second conductivity type having a portion disposed within said base region adjacent said opening in said dielectric.
Claim 28
Dependent Claim
18 words
The transistor of claim 24, wherein said base contact comprises polycrystalline silicon doped to said second conductivity type.
Claim 29
Dependent Claim
25 words
The transistor of claim 25, wherein said extrinsic base is formed by diffusion of dopant from said base contact through said opening in said dielectric.
Claim 30
Dependent Claim
62 words
The transistor of claim 24, further comprising: a collector contact formed in a trench extending from said surface to said collector region; a dielectric surrounding said collector contact in said trench, said dielectric having an opening adjacent said collector region; and a subcollector of said first conductivity type having a portion disposed within said collector region adjacent said opening in said dielectric.
Claim 31
Dependent Claim
18 words
The transistor of claim 27, wherein said collector contact comprises polycrystalline silicon doped to said first conductivity type.
Claim 32
Dependent Claim
24 words
The transistor of claim 28, wherein said subcollector is formed by diffusion of dopant from said collector contact through said opening in said dielectric.
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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) | 1994-03-25 | 1994-09-24 | 1995-03-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-03-25 | 1998-09-24 | 1999-03-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-03-25 | 2002-09-24 | 2003-03-26 | $7700.00 | Window Closed / Lapsed |