US3726726A
Expired / Lapsed
US
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Method of producing diffused highresistivity microresistors
Assignee: Tzentralen Institut Za Elementi
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Filing: 1971-01-04
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Granted: 1973-04-10
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Expires: 1991-01-04
Abstract
Abstract A METHOD OF PRODUCING DIFFUSED HIGH-RESISTIVITY MICRORESISTORS IN A SILICON WAFER WHEREIN, AFTER THE SURFACE OF THE WAFER IS CLEANED AND ETCHED TO PROVIDE WINDOWS, THE WAFER IS HEATED IN VACUUM WITH B2O3 TO DEPOSIT IMPURITY BORON ATOMS UPON THE SURFACE AND PREDIFFUSE BORON INTO THE WINDOWS. THE PREDIFFUSION TAKES PLACE AT A TEMPERATURE OF THE ORDER OF 800*C. AFTER PENETRATING DIFFUSION, THE WAFER IS EXPOSED AT THE SAME TEMPERATURE TO AN OXIDIZING ATMOSPHERE TO RENDER THE BORON ATOMS SUSCEPTIBLE TO SOLUBILIZATION IN HF. THE SURFACE IS THEN TREATED WITH AN HF ETCHANT TO REMOVE THE NONDIFFUSED IMPURITY ATOMS.
Inventors
- 👤 Y Kasabov
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:27
CPC Classifications
H; H10; H10D; H10D1/00; H10D1/40; H10D1/43; H01; H01C; H01C17/00; H01C17/06; H01C17/075; H01C17/30; H10P; H10P32/00; H10P32/10; H10P32/14; H10P32/1404; H10P32/17; H10P32/171; Y; Y10; Y10S; Y10S252/00; Y10S252/95; Y10S252/951; Y10S438/00; Y10S438/914; Y10S438/92
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) | 1976-04-09 | 1976-10-09 | 1977-04-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-09 | 1980-10-09 | 1981-04-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-09 | 1984-10-09 | 1985-04-10 | $7700.00 | Window Closed / Lapsed |