Patent US1555463A successfully refreshed from Google Patents.
Patent US3715249A successfully refreshed from Google Patents.
US3715249A
Expired / Lapsed
US
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Etching si3n4
Assignee: AT&T Inc
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Filing: 1971-09-03
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Granted: 1973-02-06
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Expires: 1991-09-03
Abstract
Abstract THE SPECIFICATION DESCRIBES A PROCESS FOR ETCHING SILICON NITRIDE IN THE PRESENCE OF SILICONE. IT HAS BEEN FOUND THAT SILICON, ESPECIALLY WHEN HIGHLY DOPED, IS ATTACHED BY THE NORMAL PHOSPHORIC ACID ETCHANT FOR SI3N4. THE ADDITION OF H2SO4 TO THE PHOSPHORIC ACID PREVENTS THE ATTACK OF SILICON.
Inventors
- 👤 P Panousis
- 👤 H Waggener
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:01
CPC Classifications
C; C09; C09K; C09K13/00; C09K13/04; H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283; Y; Y10; Y10S; Y10S148/00; Y10S148/043; Y10S148/051; Y10S148/114
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-06 | 1976-08-07 | 1977-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-06 | 1980-08-07 | 1981-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-06 | 1984-08-07 | 1985-02-06 | $7700.00 | Window Closed / Lapsed |