US4985368A
Expired / Lapsed
US
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Method for making semiconductor device with no stress generated at the trench corner portion
Assignee: Mitsubishi Electric Corp
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Filing: 1989-10-31
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Granted: 1991-01-15
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Expires: 2009-10-31
Abstract
Abstract The semiconductor device in which no stress occurs at the corner portion of the trench comprises a p type semiconductor substrate having a trench and a main surface, a thick insulating film formed on the bottom portion of the trench, a thin insulating film formed on the sidewall portion of the trench and connected to the end portion of the thick insulating film, and an n type impurity region formed in the semiconductor substrate only on the side portion of the thin insulating film.
Inventors
- 👤 Tatsuya Ishii
- 👤 Yoshinori Okumura
- 👤 Masao Nagatomo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 20:36
CPC Classifications
H; H10; H10B; H10B12/00; H10B12/01; H10B12/02; H10B12/03; H10B12/038; H10B12/30; H10B12/37; H10D; H10D1/00; H10D1/01; H10D1/045; H10D1/047; Y; Y10; Y10S; Y10S257/00; Y10S257/911
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
143 words
A method for manufacturing a semiconductor device comprising the steps of preparing a semiconductor substrate having a main surface, a predetermined impurity concentration of a first conductivity type and a trench with a large radius of curvature at at least a bottom corner portion thereof, forming a two-layer film including an oxide film and a nitride film on the main surface of said semiconductor substrate, side portions of said trench and a portion of the bottom portion of the trench, and forming a selective oxide film on the bottom portion of the trench and the corner portion thereof of said semiconductor substrate by oxidizing said semiconductor substrate with said two-layer film formed thereon, wherein the direction of extension of an end portion of said selective oxide film overlying the corner portion changes from horizontal to vertically upward with a large radius of curvature.
Claim 2
Independent Claim
143 words
A method for manufacturing a semiconductor device comprising the steps of preparing a semiconductor substrate having a main surface, a predetermined impurity concentration of a first conductivity type and a trench with a large radius of curvature at at least a bottom corner portion thereof, forming a two-layer film including an oxide film and a nitride film on the main surface of said semiconductor substrate, side portions of said trench and a portion of the bottom portion of the trench, and forming a selective oxide film on the bottom portion of the trench and the corner portion thereof of said semiconductor substrate by oxidizing said semiconductor substrate with said two-layer film formed thereon, wherein the direction of extension of an end portion of said selective oxide film overlying the corner portion changes from horizontal to vertically upward with a large radius of curvature.
Claim 3
Dependent Claim
39 words
A method for manufacturing a semiconductor device according to claim 1, wherein said curvature of said bottom corner portion is selected so as not to generate stress at said bottom corner portion when said selective oxide film is formed.
Claim 4
Dependent Claim
46 words
A method for manufacturing a semiconductor device according to claim 1, wherein the width of said trench is less than 1 μm, and the radius of curvature of said bottom corner portion is more than 1/10 and less than 1/2 of the width of said trench.
Claim 5
Dependent Claim
155 words
A method for manufacturing a semiconductor device according to claim 1, which further comprises the steps of removing the two-layer film formed on the sidewall portions of said trench, forming a first impurity region of a second conductivity type on a prescribed region of the main surface of said semiconductor substrate and on the sidewall portions of said trench, forming a first conductive layer on said first impurity region of the second conductivity type with an insulating film interposed therebetween, forming a second impurity region of the second conductivity type on the main surface of said semiconductor substrate spaced apart from said first impurity region of the second conductivity type, and forming a second conductive layer on that region of the main surface of said semiconductor substrate which region is disposed between said first region of the second conductivity type and said second region of the second conductivity type with an insulating film interposed therebetween.
Claim 6
Dependent Claim
34 words
A method for manufacturing a semiconductor device according to claim 4, wherein said first impurity region of the second conductivity type, said first conductive layer and said insulating film interposed therebetween constitute a capacitor.
Claim 7
Dependent Claim
40 words
A method for manufacturing a semiconductor device according to claim 4 wherein said first impurity region of the second conductivity type, said second impurity region of the second conductivity type and said second conductive layer constitute a field effect transistor.
Claim 8
Dependent Claim
20 words
A method for manufacturing a semiconductor device according to claim 6, wherein said semiconductor device comprises a semiconductor memory device.
Claim 9
Dependent Claim
120 words
A method for manufacturing a semiconductor device according to claim 1, wherein said oxide film of the two-layer film comprises a first oxide film and a second oxide film thinner than said first oxide film, and said step of forming said two-layer film constituted by the oxide film and the nitride film on the main surface of said semiconductor substrate and on the side portions and the corner portions of the trench comprises the steps of forming said first oxide film on the main surface of said semiconductor substrate, forming said nitride film on said first oxide film, forming said second oxide film on the sidewall portion of said trench, and forming said nitride film on said second oxide film.
Claim 10
Dependent Claim
99 words
A method for manufacturing a semiconductor device according to claim 8, wherein said step of removing said two-layer film formed on the sidewall portion of said trench comprises the steps of removing the nitride film formed on said first oxide film and on said second oxide film, and removing said first oxide film and said second oxide film simultaneously by etching from the upper portion of the films, whereby said first oxide film remains on the main surface of said semiconductor substrate at the time when said second oxide film is removed from the sidewall portion of said trench.
Claim 11
Dependent Claim
159 words
A method for manufacturing a semiconductor device according to claim 1, which further comprises the steps of removing said two-layer film formed on the sidewall portions of said trench, forming a first region of the second conductivity type on the sidewall portions of said trench and on a prescribed region of the main surface of said semiconductor substrate, forming a first conductive layer on said first impurity region of the second conductivity type with an insulating film interposed therebetween, forming second impurity regions of the second conductivity type on the main surface of said semiconductor substrate spaced apart from said first impurity region of the second conductivity type, and forming second conductive layers on that portion of the main surface of said semiconductor substrate which is disposed between said first impurity region of the second conductivity type and said second impurity region of the second conductivity type, whereby said selective oxide film constitutes a region for isolation between devices.
Claim 12
Dependent Claim
34 words
A method for manufacturing a semiconductor device according to claim 10, wherein said first impurity region of the second conductivity type, said first conductive layer and said insulating film interposed therebetween constitute a capacitor.
Claim 13
Dependent Claim
40 words
A method for manufacturing a semiconductor device according to claim 10, wherein said first impurity region of the second conductivity type, said second impurity region of the second conductivity type and said second conductive layer constitute a field effect transistor.
Claim 14
Independent Claim
142 words
A method for manufacturing a semiconductor device comprising the steps of preparing a semiconductor substrate having a main surface, a predetermined impurity concentration of a first conductivity type and a trench, forming a two-layer film constituted by an oxide film and a nitride film on the main surface of said semiconductor substrate and on that region of the sidewall portion of said trench other than the regions adjacent to the bottom portion of said trench, forming a selective oxide film on the bottom portion of the trench of said semiconductor substrate by oxidizing said semiconductor substrate with said two-layer film formed thereon with the bottom portion of said trench and the regions of the sidewall portion of said trench adjacent to said bottom portion being exposed, whereby an end portion of said selective oxide film extends only in the vertical upward direction.
Claim 15
Independent Claim
142 words
A method for manufacturing a semiconductor device comprising the steps of preparing a semiconductor substrate having a main surface, a predetermined impurity concentration of a first conductivity type and a trench, forming a two-layer film constituted by an oxide film and a nitride film on the main surface of said semiconductor substrate and on that region of the sidewall portion of said trench other than the regions adjacent to the bottom portion of said trench, forming a selective oxide film on the bottom portion of the trench of said semiconductor substrate by oxidizing said semiconductor substrate with said two-layer film formed thereon with the bottom portion of said trench and the regions of the sidewall portion of said trench adjacent to said bottom portion being exposed, whereby an end portion of said selective oxide film extends only in the vertical upward direction.
Claim 16
Dependent Claim
154 words
A method for manufacturing a semiconductor device according to claim 13, which further comprises the steps of removing the two-layer film formed on the sidewall portions of said trench, forming a first impurity region of the second conductivity type on a prescribed region of the main surface of said semiconductor substrate and on the sidewall portions of said trench, forming a first conductive layer on said first impurity region of the second conductivity type with an insulating film interposed therebetween, forming a second impurity region of the second conductivity type on the main surface of said semiconductor substrate spaced apart from said first impurity region of the second conductivity type, and forming a second conductive layer on that region of the main surface of said semiconductor substrate which is disposed between said first region of the second conductivity type and said second region of the second conductivity type with an insulating film interposed therebetween.
Claim 17
Dependent Claim
34 words
A method for manufacturing a semiconductor device according to claim 14, wherein said first impurity region of the second conductivity type, said first conductive layer and said insulating film interposed therebetween constitute a capacitor.
Claim 18
Dependent Claim
40 words
A method for manufacturing a semiconductor device according to claim 15, wherein said first impurity region of the second conductivity type, said second impurity region of the second conductivity type and said second conductive layer constitute a field effect transistor.
Claim 19
Dependent Claim
20 words
A method for manufacturing a semiconductor device according to claim 16, wherein said semiconductor device comprises a semiconductor memory device.
Claim 20
Dependent Claim
159 words
A method for manufacturing a semiconductor device according to claim 13, which further comprises the steps of removing said two-layer film formed on the sidewall portions of said trench, forming a first region of the second conductivity type on the sidewall portions of said trench and on a prescribed region of the main surface of said semiconductor substrate, forming a first conductive layer on said first impurity region of the second conductivity type with an insulating film interposed therebetween, forming second impurity regions of the second conductivity type on the main surface of said semiconductor substrate spaced apart from said first impurity region of the second conductivity type, and forming second conductive layers on that portion of the main surface of said semiconductor substrate which is disposed between said first impurity region of the second conductivity type and said second impurity region of the second conductivity type, whereby said selective oxide film constitutes a region for isolation between devices.
Claim 21
Dependent Claim
34 words
A method for manufacturing a semiconductor device according to claim 18, wherein said first impurity region of the second conductivity type, said first conductive layer and said insulating film interposed therebetween constitute a capacitor.
Claim 22
Dependent Claim
40 words
A method for manufacturing a semiconductor device according to claim 18, wherein said first impurity region of the second conductivity type, said second impurity region of the second conductivity type and said second conductive layer constitute a field effect transistor.
Claim 23
Dependent Claim
146 words
A method for manufacturing a semiconductor device according to claim 13, wherein said oxide film of said two-layer film comprises a first oxide film and a second oxide film thinner than said first oxide film, and said step of forming said two-layer film constituted by the oxide film and the nitride film on the main surface of the semiconductor substrate and on the region of the sidewall portion of said trench other than the region adjacent to the bottom portion of said trench comprises the steps of forming said first oxide film on the main surface of said semiconductor substrate, forming said nitride film on said first oxide film, forming said second oxide film on the region of the sidewall portion of the trench other than the region adjacent to the bottom portion of said trench, and forming said nitride film on said second oxide film.
Claim 24
Dependent Claim
99 words
A method for manufacturing a semiconductor device according to claim 14, wherein said step of removing said two-layer film formed on the sidewall portion of said trench comprises the steps of removing the nitride film formed on the first oxide film and on said second oxide film, and removing said first oxide film and said second oxide film by etching simultaneously from the upper portion of the films, whereby said first oxide film remains on the main surface of said semiconductor substrate at the time when the second oxide film is removed from the sidewall portion of said trench.
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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) | 1994-01-14 | 1994-07-16 | 1995-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-01-14 | 1998-07-16 | 1999-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-01-14 | 2002-07-16 | 2003-01-15 | $7700.00 | Window Closed / Lapsed |