US3960623A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Membrane mask for selective semiconductor etching
Assignee: General Electric Co
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Filing: 1974-03-14
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Granted: 1976-06-01
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Expires: 1994-03-14
Abstract
Abstract Disclosed is a method for selectively etching portions of the surface of a semiconductor body. Selected regions of the surface which are not to be etched are covered with a pliable membrane such as a plastic sheet that conforms to the shape of the body and forms a seal with the body. The combination of the membrane and body is then exposed to an etchant which only contacts the exposed portions of the body. Conformity of the membrane can be enhanced by any of several methods. For example, heat can be applied to make the membrane more pliable, a vacuum can be drawn between the membrane and the body or mechanical pressure can be applied to urge the membrane against the body. The aforementioned conformity enhancement steps are used during the covering operation, either individually or in combination.
Inventors
- 👤 Francis C. Gantley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 06:36
CPC Classifications
H; H10; H10P; H10P95/00; H10P50/00; H10P50/69; H10P50/691; H10P50/692; H10W; H10W74/00; H10W74/40; H10W74/47; Y; Y10; Y10S; Y10S156/00; Y10S156/918; Y10S156/93; Y10S438/00; Y10S438/976; Y10T; Y10T156/00; Y10T156/10; Y10T156/1002; Y10T156/1028; Y10T156/1034; Y10T156/11
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
180 words
Method of selectively etching wafers of semiconductor material, said method comprising the steps of: supplying a wafer of semiconductor material, wherein one side of said wafer is not to be etched; covering said side and at least a part of the peripheral edge therearound with a sheet of pliable plastic membrane such that said membrane conforms to the shape of said side and part of said edge and forms a seal therewith and said membrane does not contact the side of said wafer opposite said one side, said step of covering comprising the substeps of: placing said membrane on said one side; heating said membrane to enhance conformity and drawing a vacuum between said membrane and said wafer; applying mechanical pressure to said membrane to further promote uniformity; and cooling said membrane; and exposing the combination of said wafer and said membrane to an etchant so that said wafer, where exposed, is etched and said side of said wafer is not etched, and wherein said membrane and said etchant are selected so that said membrane is nonreactive with said etchant.
Claim 2
Dependent Claim
180 words
Method of selectively etching wafers of semiconductor material, said method comprising the steps of: supplying a wafer of semiconductor material, wherein one side of said wafer is not to be etched; covering said side and at least a part of the peripheral edge therearound with a sheet of pliable plastic membrane such that said membrane conforms to the shape of said side and part of said edge and forms a seal therewith and said membrane does not contact the side of said wafer opposite said one side, said step of covering comprising the substeps of: placing said membrane on said one side; heating said membrane to enhance conformity and drawing a vacuum between said membrane and said wafer; applying mechanical pressure to said membrane to further promote uniformity; and cooling said membrane; and exposing the combination of said wafer and said membrane to an etchant so that said wafer, where exposed, is etched and said side of said wafer is not etched, and wherein said membrane and said etchant are selected so that said membrane is nonreactive with said etchant.
Claim 3
Dependent Claim
28 words
A method according to claim 1 wherein said applying mechanical pressure step comprises urging said membrane against said wafer with a resilient roller to remove trapped gas bubbles.
Claim 4
Dependent Claim
39 words
A method according to claim 1 comprising, following said exposing step, the step of separating said wafer from said membrane by drawing said membrane over an edge, with said edge contacting the side of said membrane opposite said wafer.
Claim 5
Dependent Claim
20 words
A method according to claim 1 wherein said membrane is of a thickness of approximately 0.1 mil to 4 mils.
Claim 6
Dependent Claim
26 words
A method according to claim 9 wherein said wafer is silicon that is at least partially covered with silicon oxide and said etchant comprises hydrofluoric acid.
Claim 7
Dependent Claim
23 words
A method according to claim 1 wherein said wafer is silicon and said etchant comprises nitric acid, iodine, hydrofluoric acid and acetic acid.
Claim 8
Dependent Claim
18 words
A method according to claim 1 wherein said step of exposing comprises immersing said combination in said etchant.
Claim 9
Dependent Claim
44 words
A method according to claim 1 wherein said covering step comprises placing said wafer on a piece of porous material on a vacuum chuck so that said side is not in contact with said porous material and then placing said membrane over said wafer.
Claim 10
Dependent Claim
13 words
A method according to claim 8 wherein said porous material comprises filter paper.
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) | 1979-06-01 | 1979-12-01 | 1980-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-06-01 | 1983-12-01 | 1984-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-06-01 | 1987-12-01 | 1988-06-01 | $7700.00 | Window Closed / Lapsed |