Patent US4537813A successfully refreshed from Google Patents.
US4537813A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photomask encapsulation
Assignee: AT&T Inc
•
Filing: 1983-04-25
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Granted: 1985-08-27
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Expires: 2003-04-25
Abstract
Abstract A photomask (50) used for form patterns on a resist coated semiconductor wafer is comprised of a light transmissive baseplate (52) having a metallic pattern (54) thereon. A plasma deposited SiO 2 conformal, electrically resistive, coating (56) covers the patterned baseplate (52), wherein the coating material is substantially the same refractive index as the baseplate.
Inventors
- 👤 Birol Kuyel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 09:46
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/62; G03F1/64; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24802; Y10T428/24917; Y10T428/24926
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
39 words
A photomask comprising: a light transmissive, selectively metallized baseplate; and a plasma deposited, electrically resistive SiO 2 coating conformally covering the baseplate wherein the coating is a lossy dielectric and has substantially the same refractive index as the baseplate.
Claim 2
Dependent Claim
39 words
A photomask comprising: a light transmissive, selectively metallized baseplate; and a plasma deposited, electrically resistive SiO 2 coating conformally covering the baseplate wherein the coating is a lossy dielectric and has substantially the same refractive index as the baseplate.
Claim 3
Dependent Claim
17 words
The photomask according to claim 1 when a pellicle is fixedly mounted to the coated, metallized substrate.
Claim 4
Dependent Claim
21 words
The photomask according to claim 1 wherein the coating has a breakdown threshold field strength on the order of 250,000 v/cm.
Claim 5
Dependent Claim
12 words
The photomask according to claim 1 wherein the baseplate is fused silica.
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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) | 1988-08-26 | 1989-02-25 | 1989-08-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-08-26 | 1993-02-25 | 1993-08-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-08-26 | 1997-02-25 | 1997-08-27 | $7700.00 | Window Closed / Lapsed |