EP0340474A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method of making semiconductor device with different oxide film thickness
Assignee: Seiko Instruments Inc
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Filing: 1989-04-07
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Granted: —
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Expires: 2009-04-07
Abstract
Abstract A method of forming concurrently thick and thin field silicon oxide films for use as element separation on the silicon substrate. An under-layer silicon oxide film is formed over the silicon substrate. A silicon nitride film is chemically-vapor-deposited over the under-layer silicon oxide film. The silicon nitride film is selectively etched to expose the under-layer silicon oxide film to thereby form openings. The silicon substrate is annealed within heated atmosphere of ammonia gas to convert a surface portion of the exposed under-layer silicon oxide film into a thermally nitrified silicon oxide film within the openings. The thermally nitrified silicon oxide film is selectively removed from some of the openings and maintained in the other openings. The silicon substrate is thermally oxidized through the openings to concurrently form relatively thick field oxide film within said some of the openings and relatively thin field oxide film within the other openings.
Inventors
- 👤 Shoji Nakanishi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 19:45
CPC Classifications
H; H10; H10W; H10W10/00; H10W10/10; H10W10/13; H10B; H10B99/00; H10B99/22; H10P; H10P14/00; H10P14/60; H10P14/61; H10W10/01; H10W10/011; H10W10/012; H10W10/0125; Y; Y10; Y10S; Y10S438/00; Y10S438/981
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
169 words
A method of forming field silicon oxide films for use as electrical separation between circuit elements integrated on a silicon substrate, the method comprising the steps of : forming an under-layer silicon oxide film over a silicon substrate; chemically-vapor-depositing a silicon nitride film over the under-layer silicon oxide film; selectively etching the silicon nitride film to expose the under-layer silicon oxide film to thereby form a plurality of openings to which field silicon oxide films are to be formed; annealing the silicon substrate within heated atmosphere of ammonia gas to convert a surface portion of the exposed under-layer silicon oxide film into a thermally nitrified silicon oxide film within the openings; selectively removing the thermally nitrified silicon oxide film from some of the openings to which relatively thick field oxide film is to be formed; and thermally oxidizing the silicon substrate through the openings to concurrently form the relatively thick field oxide film within said some of the openings and relatively thin field oxide film within the other opening.
Claim 2
Independent Claim
169 words
A method of forming field silicon oxide films for use as electrical separation between circuit elements integrated on a silicon substrate, the method comprising the steps of : forming an under-layer silicon oxide film over a silicon substrate; chemically-vapor-depositing a silicon nitride film over the under-layer silicon oxide film; selectively etching the silicon nitride film to expose the under-layer silicon oxide film to thereby form a plurality of openings to which field silicon oxide films are to be formed; annealing the silicon substrate within heated atmosphere of ammonia gas to convert a surface portion of the exposed under-layer silicon oxide film into a thermally nitrified silicon oxide film within the openings; selectively removing the thermally nitrified silicon oxide film from some of the openings to which relatively thick field oxide film is to be formed; and thermally oxidizing the silicon substrate through the openings to concurrently form the relatively thick field oxide film within said some of the openings and relatively thin field oxide film within the other opening.
Claim 3
Dependent Claim
81 words
A method according to claim 1; wherein the step of selectively removing the thermally nitrified silicon oxide film comprises removing the thermally nitrified silicon oxide film from some of the openings located in a silicon substrate surface region in which a nonvolatile memory array is to be formed and maintaining the thermally nitrified silicon oxide film within the other openings located in another silicon substrate surface region in which a peripheral circuit for driving the memory array is to be formed.
Claim 4
Dependent Claim
29 words
A method according to claim 1; wherein the step of forming an under-layer silicon oxide film comprises thermally oxidizing the silicon substrate surface under atmosphere of heated oxygen gas.
Claim 5
Dependent Claim
33 words
A method according to claim 1; wherein the step of chemically-vapor-depositing a silicon nitride film comprises chemically-vapor-depositing a silicon nitride film within atmosphere of mixture gas of ammonia and dichlorosilane under low pressure.
Claim 6
Dependent Claim
37 words
A method according to claim 1; wherein the step of thermally oxidizing the silicon substrate comprises thermally oxidizing the silicon substrate within atmosphere of heated aqueous vapor produced by combustion of gas mixture of oxygen and hydrogen.
Claim 7
Dependent Claim
28 words
A method according to claim 1; including the step of removing the silicon nitride film and the under-layer silicon oxide film after forming the field silicon oxide films.
References Cited (Backward Citations)
No citation records indexed.
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