US4569695A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of cleaning a photo-mask
Assignee: NEC Electronics Corp
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Filing: 1984-04-20
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Granted: 1986-02-11
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Expires: 2004-04-20
Abstract
Abstract A photo-mask to be used in a light exposure step for manufacturing semiconductor devices is cleaned by wetting front and rear surfaces of the mask with a liquid, brushing the wetted surfaces with a pair of rotary brushes, wetting the brushed surfaces with an electrolytic solution containing sufficient electrolyte to substantially eliminate electrostatic charge from the surfaces, spraying and immersing the photo-mask in an organic liquid such as an alcohol, and then drying the photo-mask.
Inventors
- 👤 Hiromi Yamashita
- 👤 Toshio Wada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 23:15
CPC Classifications
H; H10; H10P; H10P72/00; H10P72/04; H10P72/0402; H10P72/0406; H10P72/0411; H10P72/0416; B; B08; B08B; B08B11/00; G; G03; G03F; G03F1/00; G03F1/68; G03F1/82; H10P72/0412; H10P72/0414
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
107 words
A method of cleaning a photo-mask to be used in a light exposure step for manufacturing semiconductor devices comprising the steps of wetting front and rear surfaces of said mask with liquid, passing said mask through a gap between a pair of rotary brushes and brushing said front and rear surfaces with said rotary brushes, making an electrolytic solution flow along said front and rear surfaces of said mask, said electrolytic solution containing sufficient electrolyte to substantially eliminate electrostatic charge from said surfaces, making an organic liquid flow along said front and rear surfaces of said mask, and drying said front and rear surfaces of said mask.
Claim 2
Independent Claim
107 words
A method of cleaning a photo-mask to be used in a light exposure step for manufacturing semiconductor devices comprising the steps of wetting front and rear surfaces of said mask with liquid, passing said mask through a gap between a pair of rotary brushes and brushing said front and rear surfaces with said rotary brushes, making an electrolytic solution flow along said front and rear surfaces of said mask, said electrolytic solution containing sufficient electrolyte to substantially eliminate electrostatic charge from said surfaces, making an organic liquid flow along said front and rear surfaces of said mask, and drying said front and rear surfaces of said mask.
Claim 3
Dependent Claim
19 words
A method of claim 1, in which said liquid in said first step is a dilute solution of ammonia.
Claim 4
Dependent Claim
22 words
A method of claim 1, in which said liquid in said first step is a weak acidic aqueous solution containing carbonic acid.
Claim 5
Dependent Claim
20 words
A method of claim 1, in which said electrolytic solution in said third step is a dilute solution of ammonia.
Claim 6
Dependent Claim
23 words
A method of claim 1, in which said electrolytic solution in said third step is a weak acidic aqueous solution containing carbonic acid.
Claim 7
Dependent Claim
17 words
A method of claim 1, in which said organic liquid in said fourth step is an alcohol.
Claim 8
Dependent Claim
20 words
A method of claim 1, in which said drying step is conducted by contacting the photo-mask with an organic gas.
References Cited (Backward Citations)
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US3117333A
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US3691582A
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US4105468A
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US4132567A
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US4169807A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-02-10 | 1989-08-12 | 1990-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-02-10 | 1993-08-12 | 1994-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-02-10 | 1997-08-12 | 1998-02-11 | $7700.00 | Window Closed / Lapsed |