Patent US5258317A successfully refreshed from Google Patents.
US5258317A
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Method for using a field implant mask to correct low doping levels at the outside edges of the base in a walled-emitter transistor structure
Assignee: Renesas Electronics America Inc
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Filing: 1992-02-13
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Granted: 1993-11-02
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Expires: 2012-02-13
Abstract
Abstract An embodiment of the present invention is a process for semiconductor device having a silicon substrate. The process comprises positioning at least one field implant mask and field implanting a silicon substrate around a bipolar active region in a substrate such that boron atoms are blocked out of an active region, and only the field region surrounding said active area is implanted, said implanting such that a predetermined layout area of a semiconductor device does not need to be increased to compensate for a BV bso problem.
Inventors
- 👤 Chuen-Der Lien
- 👤 Kyle W. Terrill
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 16:17
CPC Classifications
H; H10; H10D; H10D10/00; H10D10/01; H10D10/051; H10W; H10W10/00; H10W10/01; H10W10/011; H10W10/012; H10W10/0125; H10W10/0126; H10W10/10; H10W10/13; Y; Y10; Y10S; Y10S148/00; Y10S148/01; Y10S148/011; Y10S148/102; Y10S148/124
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
109 words
A BiCMOS process for fabrication of a walled-emitter bipolar transistor, the process comprising the steps of: applying a first mask to a substrate that includes an opening in a photoresist for defining an implant to surround a bipolar active region in said substrate; depositing a second mask on said substrate within said opening for defining said bipolar active region; ion implanting boron into said substrate to form p-wells between said field plant opening and said active area second mask; stripping off said first mask; forming a field oxide that surrounds said bipolar active region; removing said second mask; and forming a base and emitter in said bipolar active region.
Claim 2
Dependent Claim
109 words
A BiCMOS process for fabrication of a walled-emitter bipolar transistor, the process comprising the steps of: applying a first mask to a substrate that includes an opening in a photoresist for defining an implant to surround a bipolar active region in said substrate; depositing a second mask on said substrate within said opening for defining said bipolar active region; ion implanting boron into said substrate to form p-wells between said field plant opening and said active area second mask; stripping off said first mask; forming a field oxide that surrounds said bipolar active region; removing said second mask; and forming a base and emitter in said bipolar active region.
Claim 3
Dependent Claim
137 words
A BiCMOS process for fabrication of a walled-emitter transistor, the process comprising the steps of: applying a photoresist mask to a substrate that includes an opening in said photoresist for defining a field implant which will surround a bipolar active region in said substrate; depositing a nitride mask on said substrate within said opening for defining said bipolar active region; ion implanting boron into said substrate to form p-wells between said field plant opening and an active area nitride mask; stripping off said photoresist mask; forming a field oxide that surrounds said bipolar active region; removing said nitride mask; and forming a base in said bipolar active region such that said base is separated from said field oxide by said p-wells thereby inhibiting a migration of impurities in the fringes of said base to said field oxide.
Claim 4
Dependent Claim
137 words
A BiCMOS process for fabrication of a walled-emitter transistor, the process comprising the steps of: applying a photoresist mask to a substrate that includes an opening in said photoresist for defining a field implant which will surround a bipolar active region in said substrate; depositing a nitride mask on said substrate within said opening for defining said bipolar active region; ion implanting boron into said substrate to form p-wells between said field plant opening and an active area nitride mask; stripping off said photoresist mask; forming a field oxide that surrounds said bipolar active region; removing said nitride mask; and forming a base in said bipolar active region such that said base is separated from said field oxide by said p-wells thereby inhibiting a migration of impurities in the fringes of said base to said field oxide.
Claim 5
Dependent Claim
84 words
A self-aligned method of semiconductor fabrication of a walled-emitter bipolar and for solving a low BVces problem using BiCMOS technology, the method comprising the steps of: self-align implanting p-wells to surround a bipolar active region; forming a field oxide to surround said bipolar active region and to cause said p-wells to come between said field oxide and said bipolar active region; and forming a base electrode in said bipolar active region that is isolated from said field oxide by the implanting of said p-wells.
Claim 6
Dependent Claim
84 words
A self-aligned method of semiconductor fabrication of a walled-emitter bipolar and for solving a low BVces problem using BiCMOS technology, the method comprising the steps of: self-align implanting p-wells to surround a bipolar active region; forming a field oxide to surround said bipolar active region and to cause said p-wells to come between said field oxide and said bipolar active region; and forming a base electrode in said bipolar active region that is isolated from said field oxide by the implanting of said p-wells.
Claim 7
Independent Claim
46 words
A method of semiconductor fabrication of a walled-emitter bipolar transistor including an n-well, comprising the step of: blanket implanting a low dose boron implant before a field oxidation step, said low dose being limited such that the n-well will retain a relatively high field threshold voltage.
Claim 8
Independent Claim
46 words
A method of semiconductor fabrication of a walled-emitter bipolar transistor including an n-well, comprising the step of: blanket implanting a low dose boron implant before a field oxidation step, said low dose being limited such that the n-well will retain a relatively high field threshold voltage.
Claim 9
Dependent Claim
23 words
The method of claim 4, wherein: the blanket implanting comprises a dosage of 6E12 (6×10 12 ) atoms per square centimeter with boron.
References Cited (Backward Citations)
US4642883A
Cited
US4441932A
Cited
US4965220A
Cited
US4601098A
Cited
US4675981A
Cited
US4803174A
Cited
US4962053A
Cited
US4755477A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-11-01 | 1997-05-03 | 1997-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-11-01 | 2001-05-03 | 2001-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-11-01 | 2005-05-03 | 2005-11-02 | $7700.00 | Window Closed / Lapsed |