US3671437A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Etchant for selectively etching patterns in thin silicon dioxide layers and method of preparing such an etchant
Assignee: US Philips Corp
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Filing: 1970-10-16
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Granted: 1972-06-20
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Expires: 1990-10-16
Abstract
Abstract This disclosure is directed to an aqueous etching composition for silicon dioxide based on ammonium fluoride and hydrofluoric acid to which an arsenic or thallium salt has been added and to a method of etching layers of silicon dioxide by means of said etching composition.
Inventors
- 👤 Uwe Pless
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 03:38
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283
Claims Analysis
Total Claims: 1
Claim 1
Independent Claim
24 words
A process of selectively etching thin layers of silicon dioxide comprising the treating of said silicon dioxide with the etching composition of claim 1.
References Cited (Backward Citations)
FR1002026A
Cited
US3474021A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-20 | 1975-12-20 | 1976-06-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-20 | 1979-12-20 | 1980-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-20 | 1983-12-20 | 1984-06-20 | $7700.00 | Window Closed / Lapsed |