Patent US4496418A successfully refreshed from Google Patents.
US4496418A
Expired / Lapsed
US
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Process for forming an improved silicon-on-sapphire device
Assignee: Intersil Corp
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Filing: 1982-06-30
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Granted: 1985-01-29
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Expires: 2002-06-30
Abstract
Abstract A novel process is described for the removal of the objectionable point (tilt projection, appearing at the top of a silicon island). The process includes the formation of a thick insulating layer on the top surface of the island, etching the top and sides of the insulating layer to expose, at the least, the objectionable point and, thereafter, etching the objectionable point to produce a rounded edge.
Inventors
- 👤 William E. Ham
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 07:18
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/60; H10P50/64; H10P50/642; H10P50/644; H10P50/20; H10P50/24; H10P50/242; H10P50/26; H10P50/262; H10P50/263; H10P50/264; H10P50/266; H10P50/267; H10P50/268; H10P50/66; H10P50/663; H10P50/667; H10P50/69; H10P50/691; H10P50/693; H10P50/694; Y; Y10; Y10S; Y10S438/00; Y10S438/978
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
112 words
A process for forming a projection-free island of silicon, the island having slanted side walls producing a bottom surface that is broader and longer than the top surface thereof and characterized by the presence of an objectionable projecting point at the upper surface of the side walls adjacent the top surface, comprising the steps of: forming a layer of masking material covering only a central portion of the top surface of the island, the remaining uncovered portion forming a border of exposed silicon around the outer edges of the top surface thereby exposing all of the projecting point; and etching only the exposed portion of the island to remove the projecting point.
Claim 2
Dependent Claim
112 words
A process for forming a projection-free island of silicon, the island having slanted side walls producing a bottom surface that is broader and longer than the top surface thereof and characterized by the presence of an objectionable projecting point at the upper surface of the side walls adjacent the top surface, comprising the steps of: forming a layer of masking material covering only a central portion of the top surface of the island, the remaining uncovered portion forming a border of exposed silicon around the outer edges of the top surface thereby exposing all of the projecting point; and etching only the exposed portion of the island to remove the projecting point.
Claim 3
Dependent Claim
32 words
The process of claim 1, wherein: the island of silicon is formed on an insulating substrate; and the substrate is selected from the group consisting of sapphire, spinel and monocrystalline beryllium oxide.
Claim 4
Dependent Claim
16 words
The process of claim 2, wherein: the projecting point is removed by a wet chemical etch.
Claim 5
Dependent Claim
15 words
The process of claim 2, wherein: the projecting point is removed by a plasma etch.
Claim 6
Dependent Claim
16 words
The process of claim 2, wherein: the projecting point is removed by an ion beam etch.
Claim 7
Dependent Claim
194 words
A process for forming a projection free island of silicon on an insulating substrate comprising the steps of: forming a layer of silicon on the surface of an insulating substrate; forming a layer of first masking material on the layer of silicon; forming an apertured layer of second masking material on the layer of first masking material; etching the layer of first masking material through the apertures of the layer of second masking material; removing the layer of second masking material; etching the exposed portions of the layer of silicon, through the apertured layer of first masking material to form an island of silicon, the island having slanted side walls producing a base surface adjacent the substrate that is broader and longer than the top surface thereof and characterized by the presence of an objectionable point at the upper surface of the side walls adjacent the top surface; etching the layer of first masking material to form a border of exposed silicon around the outer edges of the top surface and to expose the projecting point; and etching only the exposed border on the top surface of the island to remove the projecting point.
Claim 8
Dependent Claim
194 words
A process for forming a projection free island of silicon on an insulating substrate comprising the steps of: forming a layer of silicon on the surface of an insulating substrate; forming a layer of first masking material on the layer of silicon; forming an apertured layer of second masking material on the layer of first masking material; etching the layer of first masking material through the apertures of the layer of second masking material; removing the layer of second masking material; etching the exposed portions of the layer of silicon, through the apertured layer of first masking material to form an island of silicon, the island having slanted side walls producing a base surface adjacent the substrate that is broader and longer than the top surface thereof and characterized by the presence of an objectionable point at the upper surface of the side walls adjacent the top surface; etching the layer of first masking material to form a border of exposed silicon around the outer edges of the top surface and to expose the projecting point; and etching only the exposed border on the top surface of the island to remove the projecting point.
Claim 9
Dependent Claim
21 words
The process of claim 6, wherein: the substrate is selected from the group consisting of sapphire, spinel and monocrystalline beryllium oxide.
Claim 10
Dependent Claim
16 words
The process of claim 7, wherein: the projecting point is removed by a wet chemical etch.
Claim 11
Dependent Claim
15 words
The process of claim 7, wherein: the projecting point is removed by a plasma etch.
Claim 12
Dependent Claim
16 words
The process of claim 7, wherein: the projecting point is removed by an ion beam etch.
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) | 1988-01-29 | 1988-07-30 | 1989-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-29 | 1992-07-30 | 1993-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-29 | 1996-07-30 | 1997-01-29 | $7700.00 | Window Closed / Lapsed |