US4435446A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Edge seal with polysilicon in LOCOS process
Assignee: Agilent Technologies Inc
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Filing: 1982-11-15
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Granted: 1984-03-06
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Expires: 2002-11-15
Abstract
Abstract Intrinsic polysilicon is used to seal the sidewalls of the active areas formed in a silicon substrate in an integrated circuit with no additional masking required over a standard local oxidation (LOCOS) process. Since polysilicon and silicon are compatible materials, a "bird's beak" free structure is produced with a minimum number of defects during subsequent processing.
Inventors
- 👤 Alan D. Marston
- 👤 Lenin Anne
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 21:40
CPC Classifications
H; H10; H10W; H10W10/00; H10W10/01; H10W10/011; H10W10/012; H10P; H10P50/00; H10P50/20; H10P50/26; H10P50/264; H10P50/266; H10P50/267; H10P50/268; H10P76/00; H10P76/40; H10P76/408; H10P76/4085; H10W10/10; H10W10/13; Y; Y10; Y10S; Y10S148/00; Y10S148/082
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
85 words
In a method for producing a semiconductor structure, the steps comprising: forming a covering layer over a semiconductor substrate; removing portions of the covering layer to expose desired areas on the substrate; depositing a layer of polysilicon over the entire preceding structure; anisotropically etching the polysilicon layer to remove the polysilicon in the plane parallel to the semiconductor substrate; and oxidizing the remaining polysilicon and the exposed areas of the semiconductor substrate forming a field oxide layer whereby a bird's beak free structure is produced.
Claim 2
Dependent Claim
85 words
In a method for producing a semiconductor structure, the steps comprising: forming a covering layer over a semiconductor substrate; removing portions of the covering layer to expose desired areas on the substrate; depositing a layer of polysilicon over the entire preceding structure; anisotropically etching the polysilicon layer to remove the polysilicon in the plane parallel to the semiconductor substrate; and oxidizing the remaining polysilicon and the exposed areas of the semiconductor substrate forming a field oxide layer whereby a bird's beak free structure is produced.
Claim 3
Dependent Claim
24 words
A method as in claim 1 wherein the field oxide layer is between two and six times the thickness of the deposited polysilicon layer.
Claim 4
Dependent Claim
109 words
In a method for producing a semiconductor structure, the steps comprising: forming a first oxide layer over a semiconductor substrate; depositing a second layer over the first oxide layer; forming a desired pattern in the second layer; removing the first oxide layer no longer overlain with second layer to expose areas of the semiconductor substrate; depositing a layer of polysilicon over the entire preceding structure; anisotropically etching the polysilicon layer to remove the polysilicon in the plane parallel to the semiconductor substrate; and oxidizing the remaining polysilicon layer and the exposed areas of the semiconductor substrate forming a field oxide layer whereby a bird's beak free structure is produced.
Claim 5
Dependent Claim
109 words
In a method for producing a semiconductor structure, the steps comprising: forming a first oxide layer over a semiconductor substrate; depositing a second layer over the first oxide layer; forming a desired pattern in the second layer; removing the first oxide layer no longer overlain with second layer to expose areas of the semiconductor substrate; depositing a layer of polysilicon over the entire preceding structure; anisotropically etching the polysilicon layer to remove the polysilicon in the plane parallel to the semiconductor substrate; and oxidizing the remaining polysilicon layer and the exposed areas of the semiconductor substrate forming a field oxide layer whereby a bird's beak free structure is produced.
Claim 6
Dependent Claim
24 words
A method as in claim 3 wherein the field oxide layer is between two and six times the thickness of the deposited polysilicon layer.
Claim 7
Dependent Claim
13 words
A method as in claim 3 wherein the second layer is silicon nitride.
References Cited (Backward Citations)
US4292156A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-03-06 | 1987-09-05 | 1988-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-06 | 1991-09-05 | 1992-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-06 | 1995-09-05 | 1996-03-06 | $7700.00 | Window Closed / Lapsed |