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US4839305A
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Method of making single polysilicon self-aligned transistor
Assignee: Texas Instruments Inc
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Filing: 1988-06-28
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Granted: 1989-06-13
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Expires: 2008-06-28
Abstract
Abstract A self-aligned, single polysilicon transistor is fabricated using nitride spacers (26, 68) to self-align the extrinsic base regions ( 48,80). The space between the base contacts (36,76) and the emitter contacts (34,78) is defined by the width of the nitride spacer plug (26,68) less the oxide encroachment from a thermal oxidation of the underlying polysilicon.
Inventors
- 👤 Jeffrey E. Brighton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:14
CPC Classifications
H; H10; H10D; H10D10/00; H10D10/01; H10D10/051
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
107 words
A method of forming a self-aligned transistor comprising the steps of: forming a base region in a semiconductor surface; forming a material layer over said base region; doping said material layer; forming a first masking layer over said material layer to define an emitter region; forming spacer regions on the sidewalls of said first masking layer; forming a second masking layer overlying portions of said material layer not underlying said first masking layer or said sidewall regions; removing said spacer regions; removing portions of said material layer not covered by said first or second masking layer; and diffusing dopants from said material layer into said base region.
Claim 2
Independent Claim
107 words
A method of forming a self-aligned transistor comprising the steps of: forming a base region in a semiconductor surface; forming a material layer over said base region; doping said material layer; forming a first masking layer over said material layer to define an emitter region; forming spacer regions on the sidewalls of said first masking layer; forming a second masking layer overlying portions of said material layer not underlying said first masking layer or said sidewall regions; removing said spacer regions; removing portions of said material layer not covered by said first or second masking layer; and diffusing dopants from said material layer into said base region.
Claim 3
Dependent Claim
25 words
The method of claim 1 wherein said step of forming a material layer comprises the step of forming a polysilicon layer over said base region.
Claim 4
Dependent Claim
45 words
The method of claim 1 wherein said step of forming a first masking layer comprising the steps of: forming a first masking layer overlying said material layer; and removing a portion of said first masking layer overlying said base region where a emitter is desired.
Claim 5
Dependent Claim
33 words
The method of claim 3 wherein said step of doping said material layer comprises the step of doping an area of said material layer underlying said removed portion of said first masking layer.
Claim 6
Dependent Claim
45 words
The method of claim 1 wherein said step of forming a first masking layer comprises the steps of: forming a first masking layer overlying said material layer; and removing portions of said first masking layer not overlying said base region where an emitter is desired.
Claim 7
Dependent Claim
28 words
The method of claim 5 Wherein said step of doping said material layer comprises doping the upper surface of said material layer prior to forming said masking layer.
Claim 8
Dependent Claim
30 words
The method of claim 6 and further comprising the step of removing portions of said upper surface of said material layer underlying said removed portions of said first masking layer.
Claim 9
Dependent Claim
36 words
The method of claim 1 wherein said step of forming said spacer regions comprises the steps of: forming a conformal nitride layer over said material layer and first masking layer; and anisotropically etching said nitride layer.
Claim 10
Dependent Claim
23 words
The method of claim 2 wherein said step of forming a second masking layer comprises the step of thermally oxidizing said material layer.
Claim 11
Independent Claim
123 words
A method of forming a self-aligned transistor, comprising the steps of: forming a base region in a semiconductor surface; forming a material layer overlying said base region; forming a first masking layer overlying said material layer having a window exposing said material layer and defining an emitter in said base region; forming spacer regions on the sidewalls of said window; doping a portion of said material layer overlying said defined emitter; forming a second masking layer on portions of said material layer not covered by said first masking layer or said spacer regions; removing said spacer regions; removing portions of said material layer not covered by said first or second masking layers; and diffusing dopants from said material layer into said base region.
Claim 12
Independent Claim
123 words
A method of forming a self-aligned transistor, comprising the steps of: forming a base region in a semiconductor surface; forming a material layer overlying said base region; forming a first masking layer overlying said material layer having a window exposing said material layer and defining an emitter in said base region; forming spacer regions on the sidewalls of said window; doping a portion of said material layer overlying said defined emitter; forming a second masking layer on portions of said material layer not covered by said first masking layer or said spacer regions; removing said spacer regions; removing portions of said material layer not covered by said first or second masking layers; and diffusing dopants from said material layer into said base region.
Claim 13
Dependent Claim
27 words
The method of claim 10 wherein said step of doping said material layer comprises the step of implanting a dopant through said window into said material layer.
Claim 14
Dependent Claim
27 words
The method of claim 10 and further comprising the step of removing portions of said first masking layer to define base contact regions in said material layer.
Claim 15
Dependent Claim
16 words
The method of claim 12 and further comprising the set of doping said base contact regions.
Claim 16
Independent Claim
122 words
The method of forming a self-aligned transistor, comprising the steps of: forming a base region in a semiconductor surface; forming a material layer over said base regions; doping the upper surface of said material layer; forming a first masking layer overlying said material layer and defining an emitter in said base region; removing portions of said upper surface not covered by said first mask; forming spacer regions adjacent said first mask; forming a second mask overlying portions of said material layer not covered by said first masking layer or said spacer regions; removing said spacer regions; removing portions of said material layer not covered by said first or second masking layers; and diffusing dopants from said material layer into said base region.
Claim 17
Independent Claim
122 words
The method of forming a self-aligned transistor, comprising the steps of: forming a base region in a semiconductor surface; forming a material layer over said base regions; doping the upper surface of said material layer; forming a first masking layer overlying said material layer and defining an emitter in said base region; removing portions of said upper surface not covered by said first mask; forming spacer regions adjacent said first mask; forming a second mask overlying portions of said material layer not covered by said first masking layer or said spacer regions; removing said spacer regions; removing portions of said material layer not covered by said first or second masking layers; and diffusing dopants from said material layer into said base region.
Claim 18
Dependent Claim
35 words
The method of claim 14 wherein said step of forming spacer regions comprises the steps of: forming a conformal nitride layer over said material layer in said first mask; and anisotropically etching said nitride layer.
Claim 19
Dependent Claim
35 words
The method of claim 15 wherein said step of forming a second mask comprises the step of thermally oxidizing portions of said material layer not covered by said first masking layer or said spacing regions.
Claim 20
Dependent Claim
22 words
The method of claim 14 and further comprising the steps of removing portions of said second mask to define base contact regions.
Claim 21
Dependent Claim
16 words
The method of claim 17 and further comprising the step of doping said base contact regions.
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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) | 1992-06-12 | 1992-12-12 | 1993-06-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-06-12 | 1996-12-12 | 1997-06-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-06-12 | 2000-12-12 | 2001-06-13 | $7700.00 | Window Closed / Lapsed |