US5162245A
Expired / Lapsed
US
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Self-aligned bipolar transistor using selective polysilicon growth
Assignee: Texas Instruments Inc
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Filing: 1991-06-03
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Granted: 1992-11-10
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Expires: 2011-06-03
Abstract
Abstract A polysilicon self-aligned transistor has a polysilicon layer (24) with a cavity (30) formed therein. To form the polysilicon layer (24) with a cavity (30), a thin seed layer (14) is disposed over an epitaxial layer (11a). Dielectric layers (16, 18) are formed over the seed layer (14), and are subsequently etched to define the polysilicon layer (24) and the cavity (30). The cavity (30) is defined by a dielectric plug (22). The exposed seed layer (14) is used to selectively grow the polysilicon layer (24). Thereafter, the dielectric plug (22) is removed to form the cavity (30) through which the base (32) is implanted into the substrate (12) and the emitter (36) is formed.
Inventors
- 👤 David P. Favreau
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 05:13
CPC Classifications
H; H10; H10D; H10D10/00; H10D10/01; H10D10/051; H10D62/00; H10D62/10; H10D62/13; H10D62/133; H10D64/00; H10D64/01; H10D64/011; H10D64/0111; H10D64/0113; H10D64/20; H10D64/23; H10D64/231; H10D64/27; H10D64/281; Y; Y10; Y10S; Y10S148/00; Y10S148/026
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
70 words
A method of forming a polysilicon layer overlying a semiconductor surface and forming a small cavity therein, comprising the steps of: forming a seed layer comprising silicon on the conductor surface; forming a dielectric layer overlying said seed layer; removing portions of said dielectric layer to define a plug corresponding to the desired cavity; growing polysilicon regions from said seed layer only in said remove portions; and removing said plug.
Claim 2
Independent Claim
70 words
A method of forming a polysilicon layer overlying a semiconductor surface and forming a small cavity therein, comprising the steps of: forming a seed layer comprising silicon on the conductor surface; forming a dielectric layer overlying said seed layer; removing portions of said dielectric layer to define a plug corresponding to the desired cavity; growing polysilicon regions from said seed layer only in said remove portions; and removing said plug.
Claim 3
Dependent Claim
34 words
The method of claim 1, wherein said step of forming a dielectric layer comprises the steps of: forming a nitride layer overlying said seed layer; and forming an oxide layer overlying said seed layer.
Claim 4
Dependent Claim
29 words
The method of claim 1, and further comprising the step of forming a thin oxide layer on said grown polysilicon regions after removing some or all of said plug.
Claim 5
Dependent Claim
19 words
The method of claim 1, wherein said step of forming a seed layer comprises forming a thin polysilicon layer.
Claim 6
Dependent Claim
33 words
The method of claim 4 wherein said step of forming said thin polysilicon layer comprises the step of forming a polysilicon layer having a thickness of less than or equal to 1,000 Angstroms.
Claim 7
Dependent Claim
23 words
The method of claim 1, wherein said step of forming a seed layer comprises forming an amorphous silicon layer on said semiconductor surface.
Claim 8
Dependent Claim
22 words
The method of claim 1, wherein said step of forming a dielectric layer comprises the step of depositing a TEOS oxide layer.
Claim 9
Independent Claim
96 words
A method of forming a self-aligned bipolar semiconductor structure, comprising the steps of: forming a seed layer comprising silicon on a semiconductor surface; forming a dielectric layer overlying said seed layer; removing portions of said dielectric layer to define a base contact region and not removing a portion of said dielectric layer to define an emitter contact portion; growing a polysilicon layer in said removed portion to provide a base contact; removing said dielectric portion defining an emitter contact to provide a cavity in said polysilicon layer; and forming an emitter contact region in said cavity.
Claim 10
Independent Claim
96 words
A method of forming a self-aligned bipolar semiconductor structure, comprising the steps of: forming a seed layer comprising silicon on a semiconductor surface; forming a dielectric layer overlying said seed layer; removing portions of said dielectric layer to define a base contact region and not removing a portion of said dielectric layer to define an emitter contact portion; growing a polysilicon layer in said removed portion to provide a base contact; removing said dielectric portion defining an emitter contact to provide a cavity in said polysilicon layer; and forming an emitter contact region in said cavity.
Claim 11
Dependent Claim
22 words
The method of claim 8, wherein said step of forming a seed layer comprises forming a polysilicon layer on said semiconductor surface.
Claim 12
Dependent Claim
26 words
The method of claim 8, wherein said step of forming a seed layer comprises the step of forming an amorphous silicon layer on said semiconductor surface.
Claim 13
Dependent Claim
19 words
The method of claim 8, and further comprising the step of forming a base region in said semiconductor surface.
Claim 14
Dependent Claim
26 words
The method of claim 11, wherein said step of forming a base region comprises the step implanting a dopant into the semiconductor surface through said cavity.
Claim 15
Dependent Claim
27 words
The method of claim 11, wherein said step of forming an emitter contact region comprises the step of forming a heavily doped polysilicon region in said cavity.
Claim 16
Dependent Claim
30 words
The method of claim 13, and further comprising the step of forming an emitter region within said base region by diffusing dopants from said emitter contact into said base region.
Claim 17
Dependent Claim
32 words
The method of claim 8 and further comprising the step of masking portions of said dielectric layer adjacent said base contact region prior to said step of removing portions of said dielectric.
Claim 18
Dependent Claim
36 words
The method of claim 15, wherein said step of growing a polysilicon layer comprises the step of growing said polysilicon layer to a level substantially coplanar with said unremoved dielectric portions adjacent said base contact portions.
Claim 19
Dependent Claim
48 words
The method of claim 8 and further comprising the steps of: removing a portion of said dielectric layer adjacent said polysilicon layer; and oxidizing said polysilicon layer such that an oxide region is formed between said polysilicon layer and portions of said seed layer to provide electrical isolation.
Claim 20
Independent Claim
102 words
A method of forming a self-aligned bipolar semiconductor structure, comprising the steps of: forming a seed layer comprising silicon on a semiconductor surface; forming a dielectric layer over said seed layer; masking portions of said dielectric layer where an emitter contact is desired and leaving portions of said dielectric layer unmasked where a base contact is desired; removing unmasked portions of said dielectric; growing a layer comprising silicon in said removed portions; removing said portions of said dielectric layer where an emitter contact is desired to form a void in said layer comprising silicon; and forming an emitter contact in said void.
Claim 21
Independent Claim
102 words
A method of forming a self-aligned bipolar semiconductor structure, comprising the steps of: forming a seed layer comprising silicon on a semiconductor surface; forming a dielectric layer over said seed layer; masking portions of said dielectric layer where an emitter contact is desired and leaving portions of said dielectric layer unmasked where a base contact is desired; removing unmasked portions of said dielectric; growing a layer comprising silicon in said removed portions; removing said portions of said dielectric layer where an emitter contact is desired to form a void in said layer comprising silicon; and forming an emitter contact in said void.
Claim 22
Dependent Claim
25 words
The method of claim 18, wherein said step of forming a seed layer comprises the step of forming a polysilicon layer on said semiconductor surface.
Claim 23
Dependent Claim
23 words
The method of claim 18, wherein said step of forming a seed layer comprises forming an amorphous silicon layer on said semiconductor surface.
Claim 24
Dependent Claim
27 words
The method of claim 18, and further comprising the step of forming a dielectric layer on the sidewalls of said void prior to forming said emitter contact.
References Cited (Backward Citations)
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) | 1995-11-10 | 1996-05-11 | 1996-11-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-11-10 | 2000-05-11 | 2000-11-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-11-10 | 2004-05-11 | 2004-11-10 | $7700.00 | Window Closed / Lapsed |