Patent US4940509A successfully refreshed from Google Patents.
US4940509A
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Isotropic etchant for capped silicide processes
Assignee: Texas Instruments Inc
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Filing: 1988-03-25
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Granted: 1990-07-10
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Expires: 2008-03-25
Abstract
Abstract A capped silicide process which prevents reactions between the siliciding metal and oxygen contaminants and prevents silicon outdiffusion. In one form the process entails formation of a cap layer over the metal layer prior to performing the silicide reaction and subsequent removal of the cap layer with an isotropic etchant that does not degrade the underlying silicide.
Inventors
- 👤 Stephen T. Tso
- 👤 David L. Bouldin
- 👤 Mark R. Calley
- 👤 Charlotte M. Tipton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 12:51
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/0223; C; C04; C04B; C04B41/00; C04B41/53; C04B41/5338; C04B41/5353; C04B41/80; C04B41/91; H10D64/00; H10D64/01; H10D64/013; H10D64/01302; H10D64/01304; H10D64/01306; H10D64/01308; H10D64/0131; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
86 words
A method for removing silicon nitride from a substrate having silicon nitride and titanium silicide formed thereon comprising the steps of: providing a substrate with titanium silicide and silicon nitride formed thereon; exposing said substrate to phosphoric acid having a sufficient concentration and temperature for removing said silicone nitride without adversely affecting said titanium silicide so as to etch at least a portion of said silicone nitride, said etching of said silicone nitride occuring at a faster rate than said phosphoric acid etches said titanium silicide.
Claim 2
Independent Claim
86 words
A method for removing silicon nitride from a substrate having silicon nitride and titanium silicide formed thereon comprising the steps of: providing a substrate with titanium silicide and silicon nitride formed thereon; exposing said substrate to phosphoric acid having a sufficient concentration and temperature for removing said silicone nitride without adversely affecting said titanium silicide so as to etch at least a portion of said silicone nitride, said etching of said silicone nitride occuring at a faster rate than said phosphoric acid etches said titanium silicide.
Claim 3
Dependent Claim
23 words
The method of claim 1 wherein said phosphoric acid is maintained at a temperature in the range of 140° C. to 180° C.
Claim 4
Dependent Claim
16 words
The method of claim 1 wherein said phosphoric acid solution is 84% phosphoric acid by weight.
Claim 5
Dependent Claim
19 words
A method as in claim 1 wherein said silicon nitride is formed on the surface of said titanium silicide.
Claim 6
Dependent Claim
17 words
A method as in claim 1 wherein said phosphoric acid is an aqueous solution of phosphoric acid.
References Cited (Backward Citations)
US4551908A
Cited
US4690730A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-07-09 | 1994-01-08 | 1994-07-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-09 | 1998-01-08 | 1998-07-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-09 | 2002-01-08 | 2002-07-10 | $7700.00 | Window Closed / Lapsed |