US3764423A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Removal of dielectric ledges on semiconductors
Assignee: AT&T Inc
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Filing: 1972-03-15
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Granted: 1973-10-09
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Expires: 1992-03-15
Abstract
Abstract SEMICONDUCTOR ARTICLES HAVING MULTIPLE-LAYER DIELECTRIC PROTECTIVE COVERINGS ARE USUALLY PROVIDED WITH OPENINGS THROUGH THE PROTECTIVE COVERINGS. METALLIC CONTACTS ARE MADE THROUGH THE OPENINGS TO THE UNDERLYING SEMICONDUCTTOR MATERIALS. DURING THE FORMATION OF THE OPENINGS, A LEDGE OFTEN DEVELOPS IN THE OUTER-MOST LAYER OF DIELECTRIC MATERIAL. THE TROUBLESOME LEDGE IS REMOVED BY SUBJECTING THE OUTER-MOST MATERIAL TO AN ETCHANT WHICH ETCHES AWAY SUBSTANTIALLY ONE-HALF THE ORIGINAL THICKNESS OF THE OUTER-MOST MATERIAL, BUT AT THE SAME TIME, ETCHES AWAY THE ENTIRE LEDGE SINCE THE ETCHING ACTION OCCURS FROM THE UNDERSIDE OF THE LEDGE AS WELL AS THE TOPSIDE OF THE LEDGE.
Inventors
- 👤 V Hauser
- 👤 P Panousis
- 👤 Paul Wohlheiter V De
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 07:46
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/73; H10P50/20; H10P50/28; H10P50/282; H10P50/283; H10W; H10W74/00; H10W74/40; H10W74/43
Claims Analysis
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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) | 1976-10-08 | 1977-04-09 | 1977-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-08 | 1981-04-09 | 1981-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-08 | 1985-04-09 | 1985-10-09 | $7700.00 | Window Closed / Lapsed |