US6033969A
Expired / Lapsed
US
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Method of forming a shallow trench isolation that has rounded and protected corners
Assignee: TSMC China Co Ltd
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Filing: 1996-09-30
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Granted: 2000-03-07
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Expires: 2016-09-30
Abstract
Abstract A method is provided for forming a shallow trench isolation that has rounded and protected corners by first forming a bird's beak field oxide layer prior to the trench-forming step such that a rounded and protected top corner and a rounded bottom corner of the trench can be formed. The rounded top and bottom corners of the shallow trench opening have a radius of at least 100 Å and a trench depth of not more than 5000 Å. The top corner of the trench opening is protected by the beak portion of the bird's beak against etching in a subsequent oxide dip process before gate formation.
Inventors
- 👤 Chue-San Yoo
- 👤 R. Y. Lee
- 👤 J. H. Tsai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:16
CPC Classifications
H; H10; H10W; H10W10/00; H10W10/01; H10W10/011; H10W10/012; H10W10/014; H10W10/0145; H10W10/0147; H10W10/10; H10W10/13; H10W10/17
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
169 words
A method of forming a shallow trench isolation that has rounded and protected corners comprising the steps of: providing a silicon substrate, forming a layer of silicon nitride on said substrate, forming an opening through said layer of silicon nitride and exposing a first area of said silicon substrate, forming a bird's beak field oxide layer in said first area of silicon substrate having a center portion having a thickness of at least about 500 Å and a substantially tapered edge portion, anisotropically etching said center portion of the field oxide layer not covered by said silicon nitride layer without using oxide sidewall spacers exposing a second area of said silicon substrate, anisotropically etching said silicon substrate in said exposed second area to a depth of not more than 5000 Å forming a shallow trench having rounded top and bottom corners, said substantially tapered edge portion of said field oxide layer protects said top corner of the trench from being etched, and filling said shallow trench with silicon oxide.
Claim 2
Independent Claim
169 words
A method of forming a shallow trench isolation that has rounded and protected corners comprising the steps of: providing a silicon substrate, forming a layer of silicon nitride on said substrate, forming an opening through said layer of silicon nitride and exposing a first area of said silicon substrate, forming a bird's beak field oxide layer in said first area of silicon substrate having a center portion having a thickness of at least about 500 Å and a substantially tapered edge portion, anisotropically etching said center portion of the field oxide layer not covered by said silicon nitride layer without using oxide sidewall spacers exposing a second area of said silicon substrate, anisotropically etching said silicon substrate in said exposed second area to a depth of not more than 5000 Å forming a shallow trench having rounded top and bottom corners, said substantially tapered edge portion of said field oxide layer protects said top corner of the trench from being etched, and filling said shallow trench with silicon oxide.
Claim 3
Dependent Claim
25 words
A method according to claim 1, wherein said rounded top and bottom corners in said shallow trench have a radius of at least 100 Å.
Claim 4
Dependent Claim
25 words
A method according to claim 1, wherein the opening through said layer of silicon nitride is formed by a wet etch or dry etch method.
Claim 5
Dependent Claim
40 words
A method according to claim 1, wherein said bird's beak field oxide layer is formed by exposing the silicon substrate to a temperature of not less than 900° C. and for a time period of not less than 30 minutes.
Claim 6
Dependent Claim
25 words
A method according to claim 1, where said substantially tapered edge portion having a thickness of no less than 500 Å at its thickest cross-section.
Claim 7
Dependent Claim
28 words
A method according to claim 1, wherein said anisotropic etching step for said center portion of the field oxide layer is conducted by a plasma enhanced etch method.
Claim 8
Dependent Claim
22 words
A method according to claim 6, wherein said anisotropic etching is conducted by an etchant gas of HBr/Cl 2 /He-0 2 .
Claim 9
Dependent Claim
31 words
A method according to claim 1 further comprising the step of forming a lining oxide layer on the sidewall of the shallow trench prior to filling the trench with silicon oxide.
Claim 10
Dependent Claim
21 words
A method according to claim 1, wherein said shallow trench is filled with silicon oxide by a chemical vapor deposition technique.
Claim 11
Dependent Claim
47 words
A method according to claim 1 further comprising the step of forming a paid oxide layer on said substrate prior to forming said nitride layer, and forming an opening through said layers of pad oxide and silicon nitride to expose a first area of said silicon substrate.
References Cited (Backward Citations)
US5350941A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2003-03-07 | 2003-09-06 | 2004-03-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-03-07 | 2007-09-06 | 2008-03-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-03-07 | 2011-09-06 | 2012-03-07 | $7700.00 | Window Closed / Lapsed |