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US4052253A
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Semiconductor-oxide etchant
Assignee: Motorola Solutions Inc
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Filing: 1976-09-27
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Granted: 1977-10-04
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Expires: 1996-09-27
Abstract
Abstract An etchant for semiconductors having a high preferential etch rate for doped silica particularly phosphorous doped silica, consisting of a 20:20:1 mixture, by volume, of 37% hydrochloric acid, deionized water, and 49% hydrofluoric acid. The etchant is particularly useful in a semiconductor process wherein an emitter opening is washed out following the diffusion thereof.
Inventors
- 👤 Thomas J. Kingzett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 14:33
CPC Classifications
H; H10; H10P; H10P76/00; H10P76/40; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
58 words
In a process wherein an emitter is formed in a silicon semiconductor through a diffusion window and an oxide formed thereover whereafter the emitter opening is cleaned out by immersing the silicon semiconductor in an etch solution the improvement comprising an etch consisting essentially of hydrochloric acid; hydrofluoric acid and water having a PH of less than 1.
Claim 2
Dependent Claim
58 words
In a process wherein an emitter is formed in a silicon semiconductor through a diffusion window and an oxide formed thereover whereafter the emitter opening is cleaned out by immersing the silicon semiconductor in an etch solution the improvement comprising an etch consisting essentially of hydrochloric acid; hydrofluoric acid and water having a PH of less than 1.
Claim 3
Dependent Claim
25 words
A process as recited in claim 1 wherein said etch consists of a 20:1:20 mixture by volume of 37% HCL, 49% HF and deionized water.
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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) | 1980-10-03 | 1981-04-04 | 1981-10-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-10-03 | 1985-04-04 | 1985-10-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-10-03 | 1989-04-04 | 1989-10-04 | $7700.00 | Window Closed / Lapsed |