US3807979A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Quaternary ammonium silicate for polishing silicon metal
Assignee: PQ Corp
•
Filing: 1972-05-08
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Granted: 1974-04-30
•
Expires: 1992-05-08
Abstract
Abstract I have developed an improved composition for use in the very exacting procedure of polishing soft thin wafers such as silicon which is to be used as a semi-conductor. This composition is a blend of quaternary ammonium silicate and a microfine precipitated silica whereby the proper pH for polishing with microfine silica is obtained and maintained without the necessity of continuous testing.
Inventors
- 👤 W Cromwell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:31
CPC Classifications
H; H10; H10P; H10P90/00; H10P90/12; H10P90/129
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
35 words
The dry powder of claim 1 in which the composition is 40 to 58 parts by weight of quaternary ammonium silicate and 42 to 60 parts by weight of microfine silica of low sodium content.
Claim 2
Dependent Claim
35 words
The dry powder of claim 1 in which the composition is 50 to 58 parts by weight of quaternary ammonium silicate and 42 to 50 parts by weight of microfine silica of low sodium content.
Claim 3
Dependent Claim
19 words
A dispersion of the dry powder of claim 2 having a pH in the range of 9.5 to 11.0.
Claim 4
Dependent Claim
19 words
A dispersion of the dry powder of claim 2 having a pH in the range of 10.2 to 10.6.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-04-29 | 1977-10-29 | 1978-04-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-29 | 1981-10-29 | 1982-04-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-29 | 1985-10-29 | 1986-04-30 | $7700.00 | Window Closed / Lapsed |