US4499162A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photomask and method of using same
Assignee: AT&T Inc
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Filing: 1983-06-24
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Granted: 1985-02-12
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Expires: 2003-06-24
Abstract
Abstract A photomask (60) used to form patterns on a resist coated semiconductor wafer is comprised of a light transmissive baseplate (62) having a thin metallic pattern (63) thereon; a plasma deposited coating (66) covering the patterned baseplate (62); a light transmissive, planar coverplate (68) in intimate contact with the coating (66) with an index matching fluid (72) interposed therebetween.
Inventors
- 👤 Edward L. Banks
- 👤 Thomas S. Ellington, IV
- 👤 Birol Kuyel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 13:02
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/62; G03F1/38; G03F1/48; G03F1/50; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24802; Y10T428/24851; Y10T428/24868; Y10T428/24917
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
44 words
A photomask comprising: a light transmissive baseplate having a metallic pattern thereon; a light transmissive coating covering the metallic patterned surface; and a light transmissive coverplate having opposed, substantially parallel surfaces positioned on the light transmissive coating with an index matching fluid interposed therebetween.
Claim 2
Dependent Claim
44 words
A photomask comprising: a light transmissive baseplate having a metallic pattern thereon; a light transmissive coating covering the metallic patterned surface; and a light transmissive coverplate having opposed, substantially parallel surfaces positioned on the light transmissive coating with an index matching fluid interposed therebetween.
Claim 3
Dependent Claim
16 words
The photomask as set forth in claim 1, wherein: the light transmissive coating is electrically resistive.
Claim 4
Dependent Claim
29 words
The photomask as set forth in claim 2, wherein: the baseplate, the electrically resistive coating, the coverplate, and the index matching fluid have substantially the same index of refraction.
Claim 5
Dependent Claim
16 words
The photomask as set forth in claim 2, wherein: the electrically resistive layer is plasma deposited.
Claim 6
Dependent Claim
21 words
The photomask as set forth in claim 2, wherein: the electrically resistive layer is a conformal plasma deposited SiO 2 coating.
Claim 7
Independent Claim
95 words
A method of selectively exposing a photoresist coated substrate to light radiation, comprising the steps of: positioning a photomask between a light source and a photoresist coated substrate, the photomask comprising: (a) a light transmissive baseplate having a metallic pattern thereon; (b) a light transmissive coating covering the metallic patterned surface; (c) a light transmissive coverplate, having opposed, substantially parallel surfaces, positioned on the light transmissive coating with an index matching fluid interposed therebetween; and activating the light source to direct the light radiation through the photomask to selectively expose the photoresist coated substrate thereto.
Claim 8
Independent Claim
95 words
A method of selectively exposing a photoresist coated substrate to light radiation, comprising the steps of: positioning a photomask between a light source and a photoresist coated substrate, the photomask comprising: (a) a light transmissive baseplate having a metallic pattern thereon; (b) a light transmissive coating covering the metallic patterned surface; (c) a light transmissive coverplate, having opposed, substantially parallel surfaces, positioned on the light transmissive coating with an index matching fluid interposed therebetween; and activating the light source to direct the light radiation through the photomask to selectively expose the photoresist coated substrate thereto.
Claim 9
Dependent Claim
16 words
The method as set forth in claim 6, wherein: the light transmissive coating is electrically resistive.
Claim 10
Dependent Claim
16 words
The method as set forth in claim 7, wherein: the electrically resistive coating is plasma deposited.
Claim 11
Dependent Claim
21 words
The photomask as set forth in claim 7, wherein: the electrically resistive layer is a conformal plasma deposited SiO 2 coating.
Claim 12
Independent Claim
116 words
A method of fabricating a photomask comprising the steps of: applying a metallic pattern to a transparent baseplate; applying a light transmissive coating to the metallic pattern, the light transmissive coating having approximately the same index of refraction as that of the transparent baseplate; inspecting the metallic pattern on the transparent baseplate to determine if any defect occurred during application of the light transmissive coating thereto; removably positioning a light transmissive coverplate on the light transmissive coating; sealing an index matching fluid between the coverplate and the light transmissive coating; and reinspecting the metallic pattern to determine if any defect occurred as a consequence of removably positioning the light transmissive coverplate on the light transmissive coating.
Claim 13
Independent Claim
116 words
A method of fabricating a photomask comprising the steps of: applying a metallic pattern to a transparent baseplate; applying a light transmissive coating to the metallic pattern, the light transmissive coating having approximately the same index of refraction as that of the transparent baseplate; inspecting the metallic pattern on the transparent baseplate to determine if any defect occurred during application of the light transmissive coating thereto; removably positioning a light transmissive coverplate on the light transmissive coating; sealing an index matching fluid between the coverplate and the light transmissive coating; and reinspecting the metallic pattern to determine if any defect occurred as a consequence of removably positioning the light transmissive coverplate on the light transmissive coating.
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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) | 1988-02-12 | 1988-08-13 | 1989-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-02-12 | 1992-08-13 | 1993-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-02-12 | 1996-08-13 | 1997-02-12 | $7700.00 | Window Closed / Lapsed |