Patent US3759768A successfully refreshed from Google Patents.
US3759768A
Expired / Lapsed
US
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Preferential etching of silicon
Assignee: Nortel Networks Technology Corp
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Filing: 1971-10-27
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Granted: 1973-09-18
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Expires: 1991-10-27
Abstract
Abstract PREFERENTIAL ETCHING OF SILICON-TYPICALLY ETCHING OF AN N-TYPE SILICON MATERIAL THROUGH AN ETCH RESILIENT MATERIAL, BY ETCHING WITH ORTHOPHOSPHORIC ACID TO WHICH HAS BEEN ADDED ARESENIC TRIOXIDE. THE EFFECTIVE RANGE OF ADDITIVE IS BETWEEN 0.1 GM. AND 20 GMS. OR ARSENIC TRIOXIDE PER QUART OF ACID.
Inventors
- 👤 J Lawrence
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 11:56
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/60; H10P50/64; H10P50/642; Y; Y10; Y10S; Y10S148/00; Y10S148/05; Y10S148/051; Y10S148/115; Y10S148/145
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
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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) | 1976-09-17 | 1977-03-19 | 1977-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-17 | 1981-03-19 | 1981-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-17 | 1985-03-19 | 1985-09-18 | $7700.00 | Window Closed / Lapsed |