Patent EP0253014A1 successfully refreshed from Google Patents.
EP0253014A1
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Method of manufacturing a monvolatile semiconductor memory apparatus with writing and erasing capability
Assignee: Denso Corp
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Filing: 1986-07-18
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Granted: —
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Expires: 2006-07-18
Abstract
Abstract A first polysilicon film (13) serving as an erase gate is deposited on the major surface of a semiconductor substrate (11) on which a field oxide film (12) is formed, so that the surface of the first polysilicon film is roughened. The surface of the first polysilicon film is thermally oxidized to form a first thermal oxide film (14) thereon. During the oxidation, the roughened surface of the first polysilicon film is flattened, and is duplicated by the surface of the first thermal oxide film. A second polysilicon film (15) is deposited on the roughened surface of the first thermal oxide film. The back surface of the second polysilicon film is roughened by the roughened surface of the first thermal oxide film. In this case, the surface of the second polysilicon film is also roughened. The roughened surface of the second polysilicon film is thermally oxidized in the same manner as described above to flatten its surface and to form a second thermal oxide film, the surface of which is roughened. A third polysilicon film (17) serving as a write gate is formed on the second thermal oxide film.
Inventors
- 👤 Tetsuo Fujii
- 👤 Toshio Sakakibara
- 👤 Nobuyoshi Sakakibara
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 07:35
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/60; H10D30/68; H10D30/681; H10D30/683
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
144 words
A nonvolatile semiconductor memory apparatus, in which a write or erase gate and a floating gate are stacked on a semiconductor substrate through insulating films, and which is capable of writing and erasing data, characterized in that: said erase gate comprises a first polysilicon film (13), the surface of which is flattened, a first thermal oxide film (14), the surface of which is roughened is formed on said first polysilicon film, a second polysilicon film (15), which serves as said floating gate and the surface of which is flattened is formed on the roughened surface of said first thermal oxide film, a second thermal oxide film (16), the surface of which is to be roughened, is formed on the surface of said second polysilicon film, and a third polysilicon film (17) serving as a write gate is formed on said second thermal oxide film.
Claim 2
Dependent Claim
144 words
A nonvolatile semiconductor memory apparatus, in which a write or erase gate and a floating gate are stacked on a semiconductor substrate through insulating films, and which is capable of writing and erasing data, characterized in that: said erase gate comprises a first polysilicon film (13), the surface of which is flattened, a first thermal oxide film (14), the surface of which is roughened is formed on said first polysilicon film, a second polysilicon film (15), which serves as said floating gate and the surface of which is flattened is formed on the roughened surface of said first thermal oxide film, a second thermal oxide film (16), the surface of which is to be roughened, is formed on the surface of said second polysilicon film, and a third polysilicon film (17) serving as a write gate is formed on said second thermal oxide film.
Claim 3
Dependent Claim
41 words
An apparatus according to claim 1, characterized in that said first to third polysilicon films (13, 15, 17) comprise polysilicon containing an impurity, and an impurity concentration thereof falls within the range of 1 x 10²⁰ to 7 x 10²⁰ cm⁻³.
Claim 4
Dependent Claim
36 words
An apparatus according to claim 2, characterized in that the impurity concentration of said first to third polysilicon films (13, 15, 17) preferably falls within the range of 3 x 10²⁰ to 6 x 10²⁰ cm⁻³.
Claim 5
Dependent Claim
20 words
An apparatus according to claim 2, characterized in that the impurity contained in said polysilicon (13, 15, 17) is phosphorus.
Claim 6
Dependent Claim
20 words
An apparatus according to claim 2, characterized in that the impurity contained in said polysilicon (13, 15, 17) is arsenic.
Claim 7
Dependent Claim
28 words
An apparatus according to claim 1, characterized in that said first to third polysilicon films (13, 15, 17) comprise a film which is grown in a low-temperature atmosphere.
Claim 8
Independent Claim
153 words
A method of manufacturing a nonvolative semiconductor memory apparatus, in which a write or erase gate and a floating gate are stacked on a semiconductor substrate through insulating films, and which is capable of writing and erasing data, characterized by comprising the steps of: forming a first polysilicon film (13) on the surface of said semiconductor substrate (11) so that the surface of said first polysilicon film is roughened; thermally treating said first polysilicon film formed in the previous step in an oxidation atmosphere to form a first thermal oxide film (14) on the surface of said first polysilicon film; forming a second polysilicon film (15), the surface of which is to be roughened, on at least a portion of said first thermal oxide film; thermally treating said second polysilicon film to form a second thermal oxide film (16) thereon; and forming a third polysilicon film (17) on said second thermal oxide film.
Claim 9
Independent Claim
153 words
A method of manufacturing a nonvolative semiconductor memory apparatus, in which a write or erase gate and a floating gate are stacked on a semiconductor substrate through insulating films, and which is capable of writing and erasing data, characterized by comprising the steps of: forming a first polysilicon film (13) on the surface of said semiconductor substrate (11) so that the surface of said first polysilicon film is roughened; thermally treating said first polysilicon film formed in the previous step in an oxidation atmosphere to form a first thermal oxide film (14) on the surface of said first polysilicon film; forming a second polysilicon film (15), the surface of which is to be roughened, on at least a portion of said first thermal oxide film; thermally treating said second polysilicon film to form a second thermal oxide film (16) thereon; and forming a third polysilicon film (17) on said second thermal oxide film.
Claim 10
Dependent Claim
41 words
A method according to claim 7, characterized in that said first to third polysilicon film (13, 15, 17) comprise polysilicon containing an impurity, and an impurity concentration thereof falls within the range of 1 x 10²⁰ to 7 x 10²⁰ cm⁻³.
Claim 11
Dependent Claim
37 words
9, A method according to claim 8, characterized in that the impurity concentration of said first to third polysilicon films (13, 15, 17) preferably falls within the range of 3 x 10²⁰ to 6 x 10²⁰ cm⁻³.
Claim 12
Dependent Claim
27 words
A method according to claim 8, characterized in that the impurity contained in the polysilicon constituting said first to third polysilicon films (13, 15, 17) is phosphorus.
Claim 13
Dependent Claim
27 words
A method according to claim 8, characterized in that the impurity contained in the polysilicon constituting said first to third polysilicon films (13, 15, 17) is arsenic.
Claim 14
Dependent Claim
39 words
A method according to claim 7, characterized in that the steps of forming said first to third polysilicon films (13, 15, 17) are achieved by means for growing polysilicon on said thermal oxide films respectively in a low-temperature atmosphere.
Claim 15
Dependent Claim
24 words
A method according to claim 12, characterized in that the temperature of the atmosphere for growth falls within the range of 550 to 650°C.
Claim 16
Dependent Claim
25 words
A method according to claim 7, characterized in that said first to third polysilicon films (13, 15, 17) are formed by a low-pressure CVD method.
Claim 17
Dependent Claim
45 words
A method according to claim 7, characterized in that the steps of forming said first and/or second thermal oxide films (14, 16) are steps of thermally oxidizing the surface of said first and/or second polysilicon films (13, 15) at a temperature of 900 to 1,300°C.
Claim 18
Dependent Claim
22 words
A method according to claim 15, characterized in that the thermal oxidation temperature preferably falls within the range of 1,000 to 1,200°C.
Claim 19
Dependent Claim
27 words
A method according to claim 7, characterized in that said first and/or second thermal oxide films (14, 16) are formed by oxidation in a dry oxygen atmosphere.
Claim 20
Dependent Claim
32 words
A method according to claim 7, characterized in that said first and/or second thermal oxide films (14, 16) are formed by oxidation in an atmosphere of a dry oxygen gas containing chlorine.
References Cited (Backward Citations)
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