US5445986A
Expired / Lapsed
US
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Method of forming a roughened surface capacitor with two etching steps
Assignee: NEC Corp
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Filing: 1994-09-01
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Granted: 1995-08-29
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Expires: 2014-09-01
Abstract
Abstract In a method of manufacturing a semiconductor device having a capacitor constituted by a lower electrode, an upper electrode, and a dielectric film arranged between the lower and upper electrodes, a polysilicon film containing a Group V element as an impurity is formed. The first etching step of forming an uneven portion on a surface of the polysilicon film is performed. The second etching step of forming an uneven portion on the surface of the polysilicon film is performed. The second etching step has an etch rate whose impurity concentration dependency is different from an impurity concentration dependency of an etch rate of the first etching step, thereby forming the uneven portion on the surface of the polysilicon film.
Inventors
- 👤 Toshiyuki Hirota
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:29
CPC Classifications
H; H10; H10D; H10D1/00; H10D1/60; H10D1/68; H10D1/692; H10D1/711; H10D1/712; H10B; H10B12/00; H10B12/01; H10P; H10P50/00; H10P50/60; H10P50/66; H10P50/663; H10P50/667; Y; Y10; Y10S; Y10S438/00; Y10S438/964
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
126 words
A method of manufacturing a semiconductor device having a capacitor constituted by a lower electrode, an upper electrode, and a dielectric film arranged between said lower and upper electrodes, wherein said lower electrode is formed by comprising: the step of forming a polysilicon film containing a Group V element as an impurity; the first etching step of forming an uneven portion on a surface of said polysilicon film; and the second etching step of forming an uneven portion on the surface of said polysilicon film, and the second etching step having an etch rate whose impurity concentration dependency is different from an impurity concentration dependency of an etch rate of the first etching step, thereby forming the uneven portion on the surface of said polysilicon film.
Claim 2
Independent Claim
126 words
A method of manufacturing a semiconductor device having a capacitor constituted by a lower electrode, an upper electrode, and a dielectric film arranged between said lower and upper electrodes, wherein said lower electrode is formed by comprising: the step of forming a polysilicon film containing a Group V element as an impurity; the first etching step of forming an uneven portion on a surface of said polysilicon film; and the second etching step of forming an uneven portion on the surface of said polysilicon film, and the second etching step having an etch rate whose impurity concentration dependency is different from an impurity concentration dependency of an etch rate of the first etching step, thereby forming the uneven portion on the surface of said polysilicon film.
Claim 3
Dependent Claim
42 words
A method according to claim 1, wherein an etching medium used in the first etching step has an etch rate whose impurity concentration dependency is larger than that of an etch rate of an etching medium used in the second etching step.
Claim 4
Dependent Claim
19 words
A method according to claim 2, wherein the etching media used-in the first and second etching steps are liquids.
Claim 5
Dependent Claim
20 words
A method according to claim 2, wherein the etching media used in the first and second etching steps are gases.
Claim 6
Dependent Claim
26 words
A method according to claim 1, wherein the first etching step includes the step of exposing said polysilicon film to a medium containing a phosphoric acid.
Claim 7
Dependent Claim
34 words
A method according to claim 1, wherein the first etching step includes the step of exposing said polysilicon to a solution mixture of a hydrofluoric acid, a nitric acid, and a glacial acetic acid.
Claim 8
Dependent Claim
27 words
A method according to claim 1, wherein the second etching step includes the step of exposing said polysilicon film to a solution containing ammonia and hydrogen peroxide.
Claim 9
Dependent Claim
35 words
A method according to claim 1, wherein the second etching step includes the step of oxidizing a surface of said polysilicon prospectively serving as said lower electrode and the step of using a hydrofluoric acid.
Claim 10
Dependent Claim
47 words
A method according to claim 7, further comprising, after a process of said second etching step is performed, the step of removing a surface oxide film and the step of performing rapid thermal nitriding in an ammonia atmosphere, and then forming an insulating film of said capacitor.
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US5134086A
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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) | 1998-08-28 | 1999-02-27 | 1999-08-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-08-28 | 2003-02-27 | 2003-08-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-08-28 | 2007-02-27 | 2007-08-29 | $7700.00 | Window Closed / Lapsed |