US4402600A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photomask for producing semiconductor devices
Assignee: Fujitsu Ltd
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Filing: 1981-10-23
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Granted: 1983-09-06
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Expires: 2001-10-23
Abstract
Abstract A photomask comprises a transparent substrate on one surface of which a mask pattern is formed of a photoshielding film and the opposite surface of which is roughened in order that rays of incident light are refracted diffusedly through the rough surface and the images of minute particles of dust disappear in the projected pattern.
Inventors
- 👤 Satoshi Araihara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 03:57
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/60; G03F1/50
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
61 words
A photomask comprising a transparent substrate on one surface of which a mask pattern is formed of a photoshielding film characterized in that the opposite surface to said one surface provided with said mask pattern is roughened in order that rays of incident light from said opposite surface side toward said one surface side are refracted diffusedly through said rough surface.
Claim 2
Dependent Claim
61 words
A photomask comprising a transparent substrate on one surface of which a mask pattern is formed of a photoshielding film characterized in that the opposite surface to said one surface provided with said mask pattern is roughened in order that rays of incident light from said opposite surface side toward said one surface side are refracted diffusedly through said rough surface.
Claim 3
Dependent Claim
63 words
An improved photomask comprising: a transparent substrate; means on one surface of said transparent substrate for providing a photo-shielding pattern; and further means on the other surface of said transparent substrate for effecting diffusion of rays of light directed from said other surface to said one surface so that contaminant particles on the substrate will not appear on a surface to be patterned.
Claim 4
Dependent Claim
63 words
An improved photomask comprising: a transparent substrate; means on one surface of said transparent substrate for providing a photo-shielding pattern; and further means on the other surface of said transparent substrate for effecting diffusion of rays of light directed from said other surface to said one surface so that contaminant particles on the substrate will not appear on a surface to be patterned.
Claim 5
Dependent Claim
55 words
An improved photomask comprising: a transparent substrate; a photo-shielding film on one surface of said transparent substrate for providing a photo-shielding pattern; and further means on the other surface of said transparent substrate for effecting diffusion of rays of light directed thereon so that contaminant particles will not appear on a surface to be patterned.
Claim 6
Dependent Claim
55 words
An improved photomask comprising: a transparent substrate; a photo-shielding film on one surface of said transparent substrate for providing a photo-shielding pattern; and further means on the other surface of said transparent substrate for effecting diffusion of rays of light directed thereon so that contaminant particles will not appear on a surface to be patterned.
Claim 7
Dependent Claim
16 words
An improved photomask as set forth in claim 3, wherein said photo-shielding film consists of chromium.
Claim 8
Dependent Claim
17 words
An improved photomask as set forth in claim 3, wherein said photo-shielding film consists of chromium oxide.
Claim 9
Dependent Claim
32 words
An improved photomask as set forth in claim 3, wherein said further means for effecting light ray diffusion on the other surface of said transparent substrate comprises said other surface being roughened.
Claim 10
Dependent Claim
19 words
An improved photomask as set forth in claim 6, wherein said other surface is roughened less than 50 μm.
Claim 11
Dependent Claim
19 words
An improved photomask as set forth in claim 6, wherein said other surface is roughened more than 1 μm.
Claim 12
Dependent Claim
21 words
An improved photomask as set forth in claim 6, wherein said other surface is roughened between 1 μm and 50 μm.
Claim 13
Dependent Claim
23 words
An improved photomask as set forth in claim 2, wherein said further means comprises said other surface being roughened less than 50 μm.
Claim 14
Dependent Claim
23 words
An improved photomask as set forth in claim 2, wherein said further means comprises said other surface being roughened more than 1 μm.
Claim 15
Dependent Claim
25 words
An improved photomask as set forth in claim 2, wherein said further means comprises said other surface being roughened between 1 μm and 50 μm.
References Cited (Backward Citations)
US3507593A
Cited
US3811893A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-09-05 | 1987-03-07 | 1987-09-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-05 | 1991-03-07 | 1991-09-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-05 | 1995-03-07 | 1995-09-06 | $7700.00 | Window Closed / Lapsed |