US3592707A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Precision masking using silicon nitride and silicon oxide
Assignee: AT&T Inc
•
Filing: 1968-06-17
•
Granted: 1971-07-13
•
Expires: 1988-06-17
Abstract
Abstract A SILICON OXIDE MASK DEFINES THE DIFFUSION OF A CONDUCTIVITY TYPE ZONE IN A SEMICONDUCTOR BODY. THE SURFACE OF THE DIFFUSED ZONE THEN IS COVERED BY A LAYER OF SILICON NITRIDE WHICH IS SELECTIVELY ETCHED USING PHOSPHORIC ACID. THIS ETCHANT REMOVES THE PERIPHERAL PORTIONS LEAVING A CENTRAL PORTION OF SILICON NITRIDE. THE SEMICONDUCTOR BODY THEN IS TREATED TO REPLACE THE REMOVED SILICON NITRIDE WITH SILICON OXIDE AFTER WHICH THE REMAINING CENTRAL PORTION OF SILICON NITRIDE IS REMOVED, LEAVING A WINDOW TO THE SEMICONDUCTOR BODY SURFACE WHICH IS REGISTERED WITH RESPECT TO THE DIFFUSED ZONE AND OF FINE DIMENSIONS DETERMINED BY THE ETCHING PROCESS.
Inventors
- 👤 Ralph J Jaccodine
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:48
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283; H10W; H10W74/00; H10W74/40; Y; Y10; Y10S; Y10S148/00; Y10S148/043; Y10S148/114
Claims Analysis
Total Claims: 0
No claims parsed yet. Click Sync Now above to re-index claims from Google Patents.
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) | 1974-07-12 | 1975-01-11 | 1975-07-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-07-12 | 1979-01-11 | 1979-07-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-07-12 | 1983-01-11 | 1983-07-13 | $7700.00 | Window Closed / Lapsed |