US4099997A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of fabricating a semiconductor device
Assignee: RCA Corp
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Filing: 1976-06-21
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Granted: 1978-07-11
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Expires: 1996-06-21
Abstract
Abstract A method of fabricating a semiconductor device having a one type conductivity portion substantially surrounded by a second type conductivity portion is disclosed. The method involves selectively diffusing different impurities having the same conductivity inducing effect. The disclosed method is particularly adaptable to forming a plurality of devices in a relatively thick semiconductor wafer.
Inventors
- 👤 Wojciech Rosnowski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 12:13
CPC Classifications
H; H10; H10P; H10P32/00; H10D; H10D18/00
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
199 words
A method of fabricating a semiconductor device comprising the steps of: forming a source of first impurities of one conductivity determining type on each of two major opposing surfaces of a semiconductor wafer, said wafer containing opposite type determining impurities; disposing a layer of masking material over said source of first impurities; defining said layer and said source of first impurities to expose preselected portions of said surfaces; exposing said wafer to a source of second impurities of said one conductivity determining type in such a manner that said second impurities diffuse into said wafer through said preselected portions, said first impurities simultaneously penetrating said unexposed portions of said wafer, said second impurities being masked from the unexposed portions of said surfaces by said source of first impurities and said masking layer, said second impurities having a comparatively higher diffusivity in said wafer than said first impurities; and thereafter removing said masking layer and said source of first impurities; and thereafter heating said wafer to a temperature at which said first impurities and said second impurities further penetrate said wafer for a time long enough so that said second impurities form first continuous regions between said two opposing surfaces.
Claim 2
Independent Claim
199 words
A method of fabricating a semiconductor device comprising the steps of: forming a source of first impurities of one conductivity determining type on each of two major opposing surfaces of a semiconductor wafer, said wafer containing opposite type determining impurities; disposing a layer of masking material over said source of first impurities; defining said layer and said source of first impurities to expose preselected portions of said surfaces; exposing said wafer to a source of second impurities of said one conductivity determining type in such a manner that said second impurities diffuse into said wafer through said preselected portions, said first impurities simultaneously penetrating said unexposed portions of said wafer, said second impurities being masked from the unexposed portions of said surfaces by said source of first impurities and said masking layer, said second impurities having a comparatively higher diffusivity in said wafer than said first impurities; and thereafter removing said masking layer and said source of first impurities; and thereafter heating said wafer to a temperature at which said first impurities and said second impurities further penetrate said wafer for a time long enough so that said second impurities form first continuous regions between said two opposing surfaces.
Claim 3
Dependent Claim
20 words
The method as claimed in claim 1 wherein: said first impurities form second continuous regions between said first continuous regions.
Claim 4
Dependent Claim
39 words
A method as claimed in claim 1 wherein said step of forming said source of first impurities comprises: forming a first layer of material containing said first impurities on each of two major opposing surfaces of a semiconductor wafer.
Claim 5
Dependent Claim
35 words
The method as claimed in claim 3 wherein said first layer forming step comprises: reacting silane and diborane in the presence of said wafer whereby a borosilicate glass is deposited on each of said surfaces.
Claim 6
Dependent Claim
28 words
The method as claimed in claim 4 further comprising: reacting said silane and said diborane in such proportion that said borosilicate glass contains about 17% boron by weight.
Claim 7
Dependent Claim
31 words
The method as claimed in claim 4 further comprising the step of: carrying out said reaction until about 6000 A of said borosilicate glass is deposited on each of said surfaces.
Claim 8
Dependent Claim
27 words
The method as claimed in claim 1 wherein: said step of forming said layer of masking material comprises chemically depositing silicon dioxide from a vapor containing silane.
Claim 9
Dependent Claim
19 words
The method as claimed in claim 7 further comprising the step of: annealing said second layer of masking material.
Claim 10
Dependent Claim
30 words
The method as claimed in claim 8 wherein said annealing step comprises: heating said second layer of masking material to a temperature of about 900° C for about 30 minutes.
Claim 11
Dependent Claim
25 words
The method as claimed in claim 1 further comprising the step of: selectively exposing portions of said two opposing surfaces which portions oppose each other.
Claim 12
Dependent Claim
21 words
The method as claimed in claim 1 wherein: said exposing step comprises exposing said portions to a source of aluminum impurities.
Claim 13
Dependent Claim
23 words
The method as claimed in claim 1 wherein: said heating step comprises heating said wafer to about 1300° C for about 20 hours.
Claim 14
Dependent Claim
22 words
The method as claimed in claim 1 further comprising: selecting boron as said first impurity and selecting aluminum as said second impurity.
Claim 15
Dependent Claim
27 words
The method as claimed in claim 1 wherein: said step of disposing said layer of masking material comprises chemically depositing silicon dioxide from a vapor containing silane.
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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) | 1981-07-10 | 1982-01-09 | 1982-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-07-10 | 1986-01-09 | 1986-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-07-10 | 1990-01-09 | 1990-07-11 | $7700.00 | Window Closed / Lapsed |