US4056414A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing an improved dielectrically-isolated silicon crystal utilizing adjacent areas of different insulators
Assignee: Fairchild Semiconductor Corp
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Filing: 1976-11-01
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Granted: 1977-11-01
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Expires: 1996-11-01
Abstract
Abstract Thermoprocessing of integrated-circuit devices and ionizing radiation environments create electronic charges in dielectric isolation materials and in dielectric-semiconductor interface regions. These charges can produce serious alterations in the operating characteristics of the devices and integrated circuits. The deleterious effect of these charges may be greatly reduced by the disclosed process which produces a single-crystal silicon film dielectrically isolated from a polycrystalline silicon support by an underlying insulator of either silicon nitride or silicon dioxide, both of which may be grown by the process at selected locations on the same chip.
Inventors
- 👤 Robert J. Kopp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:17
CPC Classifications
H; H10; H10P; H10P90/00; H10P90/19; H10P90/1904; H10P90/1906; H10W; H10W10/00; H10W10/01; H10W10/021; H10W10/061; H10W10/10; H10W10/181; H10W10/20; Y; Y10; Y10S; Y10S438/00; Y10S438/914; Y10S438/924; Y10S438/977
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
207 words
A method for fabricating single-crystal silicon films dielectrically isolated from each other and from a common substrate by silicon dioxide and silicon nitride insulating films, said method comprising the steps of: epitaxially growing a silicon film to a thickness of approximately four micrometers on the surface of a heavily-doped n-type single-crystal silicon wafer; coating the surface of said silicon film with a first dielectric material to a thickness of approximately 0.2 micrometers; masking all portions of the surface of said first dielectric material that are to be retained for dielectric isolation and removing all portions of said first dielectric material that are not masked and are to be isolated by a second dielectric material; coating the areas on the surface of said silicon film that have been exposed by the removal of portions of said first dielectric material with a second dielectric material; depositing on the exposed surfaces of said first and second dielectric materials a relatively thick supporting layer of polycrystalline silicon; removing said heavily-doped n-type silicon wafer by electrochemically etching it from said epitaxially-grown silicon film; vapor thinning said silicon film to a desired thickness; and selectively etching through said silicon film to form individual single-crystal device islands on said first and second dielectric materials.
Claim 2
Independent Claim
207 words
A method for fabricating single-crystal silicon films dielectrically isolated from each other and from a common substrate by silicon dioxide and silicon nitride insulating films, said method comprising the steps of: epitaxially growing a silicon film to a thickness of approximately four micrometers on the surface of a heavily-doped n-type single-crystal silicon wafer; coating the surface of said silicon film with a first dielectric material to a thickness of approximately 0.2 micrometers; masking all portions of the surface of said first dielectric material that are to be retained for dielectric isolation and removing all portions of said first dielectric material that are not masked and are to be isolated by a second dielectric material; coating the areas on the surface of said silicon film that have been exposed by the removal of portions of said first dielectric material with a second dielectric material; depositing on the exposed surfaces of said first and second dielectric materials a relatively thick supporting layer of polycrystalline silicon; removing said heavily-doped n-type silicon wafer by electrochemically etching it from said epitaxially-grown silicon film; vapor thinning said silicon film to a desired thickness; and selectively etching through said silicon film to form individual single-crystal device islands on said first and second dielectric materials.
Claim 3
Dependent Claim
14 words
The method claimed in claim 1 wherein said epitaxially-grown silicon film is p-type silicon.
Claim 4
Dependent Claim
15 words
The method claimed in claim 1 wherein said epitaxially-grown silicon film is lightly-doped n-type silicon.
Claim 5
Dependent Claim
22 words
The method claimed in claim 1 wherein said first dielectric material is silicon dioxide and said second dielectric material is silicon nitride.
Claim 6
Dependent Claim
20 words
The method claimed in claim 4 further including the step of: passivating said device islands with a silicon dioxide coating.
Claim 7
Dependent Claim
22 words
The method claimed in claim 1 wherein said first dielectric material is silicon nitride and said second dielectric material is silicon dioxide.
Claim 8
Dependent Claim
49 words
The method claimed in claim 6 wherein said step of coating the surface of said silicon film with silicon nitride is followed by the additional step of: coating the surface of said silicon nitride with a layer of silicon dioxide to serve as a mask against silicon nitride etching.
Claim 9
Dependent Claim
20 words
The method claimed in claim 7 wherein unmasked portions of said silicon nitride are removed by hot phosphoric acid etch.
Claim 10
Dependent Claim
20 words
The method claimed in claim 8 further including the step of: passivating said device islands with a silicon dioxide coating.
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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) | 1980-10-31 | 1981-05-02 | 1981-11-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-10-31 | 1985-05-02 | 1985-11-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-10-31 | 1989-05-02 | 1989-11-01 | $7700.00 | Window Closed / Lapsed |