Patent US4256535A successfully refreshed from Google Patents.
US4256535A
Expired / Lapsed
US
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Method of polishing a semiconductor wafer
Assignee: AT&T Inc
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Filing: 1979-12-05
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Granted: 1981-03-17
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Expires: 1999-12-05
Abstract
Abstract A semiconductor wafer (31) is placed on a non-porous, flat, substrate (10), with a thin layer of water (21) interposed therebetween. The substrate (10) with the wafer (31) thereon is placed in a polishing machine (40) where a rotating polishing pad (43) polishes the wafer which is permitted to float free and rotate on the thin layer of water (21) during the polishing operation.
Inventors
- 👤 Edward L. Banks
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 21:05
CPC Classifications
B; B24; B24B; B24B37/00; B24B37/27; B24B37/30; C; C30; C30B; C30B33/00; Y; Y10; Y10S; Y10S438/00; Y10S438/959
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
62 words
A method of polishing a semiconductor wafer having first and second major surfaces, comprising the steps of: (a) placing the first major surface of the wafer on a flat non-porous substrate with a liquid interposed therebetween; (b) polishing the second major surface of the wafer with a rotating polishing pad; and (c) permitting free floating, rotative motion of the wafer during polishing.
Claim 2
Independent Claim
62 words
A method of polishing a semiconductor wafer having first and second major surfaces, comprising the steps of: (a) placing the first major surface of the wafer on a flat non-porous substrate with a liquid interposed therebetween; (b) polishing the second major surface of the wafer with a rotating polishing pad; and (c) permitting free floating, rotative motion of the wafer during polishing.
Claim 3
Dependent Claim
41 words
The method as set forth in claim 1, characterized by: prior to step (a); lapping the wafer to a flatness of about one micron; and etching the wafer to remove approximately one mil of material from each side of the wafer.
Claim 4
Dependent Claim
20 words
The method as set forth in claim 2, wherein: the wafer was etched in an acidic etch at 50° C.
Claim 5
Dependent Claim
20 words
The method as set forth in claim 2, wherein: the wafer was etched in a caustic etch at 90° C.
Claim 6
Dependent Claim
13 words
The method as set forth in claim 1, wherein: the liquid is water.
Claim 7
Dependent Claim
13 words
The method as set forth in claim 1, wherein: the wafer is silicon.
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) | 1984-03-16 | 1984-09-15 | 1985-03-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-16 | 1988-09-15 | 1989-03-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-16 | 1992-09-15 | 1993-03-17 | $7700.00 | Window Closed / Lapsed |