Patent US4644170A successfully refreshed from Google Patents.
US4644170A
Expired / Lapsed
US
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Method of electron beam exposure
Assignee: Toshiba Corp
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Filing: 1985-12-20
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Granted: 1987-02-17
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Expires: 2005-12-20
Abstract
Abstract A method of electron beam exposure comprising selectively exposing a resist film on a substrate a plurality of times with an electron beam whose dose is lower than a desired dose sufficient to produce a difference in molecular weight between the exposed area and the nonexposed area, the cumulative dose corresponding to said desired dose.
Inventors
- 👤 Fumio Komatsu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:09
CPC Classifications
H; H10; H10P; H10P95/00; B; B82; B82Y; B82Y10/00; B82Y40/00; H01; H01J; H01J37/00; H01J37/30; H01J37/317; H01J37/3174; H01J2237/00; H01J2237/30; H01J2237/317; H01J2237/3175; H01J2237/31769; H01J2237/31771
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
133 words
A method of forming a pattern on a resist film disposed on a substrate, comprising the steps of: exposing the portions of said resist film containing said pattern with an electron beam of a reduced dose that is a fraction of a desired dose while refraining from exposing the portions of said resist film not containing said pattern, said desired dose being sufficient to produce a difference in molecular weight between said patterned portions of said resist film and the nonexposed portions of said resist film; and said fraction having 1 as a numerator and a whole number as a denominator; and performing said exposing step a number of times equal to said denominator of said fraction to expose said portions to a cumulative electron beam dose substantially equal to said desired dose.
Claim 2
Independent Claim
133 words
A method of forming a pattern on a resist film disposed on a substrate, comprising the steps of: exposing the portions of said resist film containing said pattern with an electron beam of a reduced dose that is a fraction of a desired dose while refraining from exposing the portions of said resist film not containing said pattern, said desired dose being sufficient to produce a difference in molecular weight between said patterned portions of said resist film and the nonexposed portions of said resist film; and said fraction having 1 as a numerator and a whole number as a denominator; and performing said exposing step a number of times equal to said denominator of said fraction to expose said portions to a cumulative electron beam dose substantially equal to said desired dose.
Claim 3
Dependent Claim
14 words
A method according to claim 1, in which said substrate is a silicon wafer.
Claim 4
Dependent Claim
14 words
A method according to claim 1, in which said substrate is a blank mask.
Claim 5
Dependent Claim
25 words
A method according to claim 1, in which said reduced electron beam dose has a beam current lower than the current of said desired dose.
Claim 6
Dependent Claim
30 words
A method according to claim 4, in which said exposing step is performed twice, and said reduced dose has a beam current one half the current of said desired dose.
Claim 7
Dependent Claim
30 words
A method according to claim 4, in which said exposing step is performed thrice, and said reduced dose has a beam current one third the current of said desired dose.
Claim 8
Dependent Claim
26 words
A method according to claim 1, in which said reduced electron beam dose has an exposure time shorter than the exposure time of said desired dose.
Claim 9
Dependent Claim
31 words
A method according to claim 7, in which said exposing step is performed twice, and said reduced dose has an exposure time one half the exposure time of said desired dose.
Claim 10
Dependent Claim
31 words
A method according to claim 7, in which said exposing step is performed thrice, and said reduced dose has an exposure time one third the exposure time of said desired dose.
References Cited (Backward Citations)
FR2151130A1
Cited
FR2375665A1
Cited
DE2852961A1
Cited
US4298803A
Cited
DE2927242A1
Cited
JPS56112729A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-02-16 | 1990-08-18 | 1991-02-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-16 | 1994-08-18 | 1995-02-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-16 | 1998-08-18 | 1999-02-17 | $7700.00 | Window Closed / Lapsed |