Patent EP0371656A2 successfully refreshed from Google Patents.
US4704342A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photomask having a patterned carbon light-blocking coating
Assignee: Fairchild Semiconductor Corp
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Filing: 1985-04-02
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Granted: 1987-11-03
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Expires: 2005-04-02
Abstract
Abstract A photomask for use in manufacturing integrated circuits is fabricated by coating a thin film of organic material, generally a solution of a thermally decomposable hydrocarbon, onto a glass plate and heating it in a reducing atmosphere to convert it into carbon. The carbon layer is masked and etched; for example, in an oxygen plasma, to produce the mask.
Inventors
- 👤 William I. Lehrer
- 👤 P. Anthony Crossley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 18:41
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/54; G03F1/56; Y; Y10; Y10S; Y10S430/00; Y10S430/146
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
71 words
A method of fabricating a photomask blank for use in the manufacture of integrated circuits which comprises: coating a photomask substrate by depositing a solution of a carbon precursor on the surface of the substrate and spinning the substrate to distribute the solution into a uniform film which covers the entire surface of the substrate; and heating the thus-coated substrate in a reducing atmosphere to form a light-blocking layer of carbon.
Claim 2
Independent Claim
71 words
A method of fabricating a photomask blank for use in the manufacture of integrated circuits which comprises: coating a photomask substrate by depositing a solution of a carbon precursor on the surface of the substrate and spinning the substrate to distribute the solution into a uniform film which covers the entire surface of the substrate; and heating the thus-coated substrate in a reducing atmosphere to form a light-blocking layer of carbon.
Claim 3
Dependent Claim
20 words
The method of claim 1 wherein said solution of a carbon precursor is a solution of a decomposable organic material.
Claim 4
Dependent Claim
23 words
The method of claim 1 wherein a photomask is formed by masking selective portions of the carbon-coated substrate and etching the unmasked portions.
Claim 5
Dependent Claim
15 words
The method of claim 3 wherein said etching is conducted with an oxygen-based plasma system.
Claim 6
Dependent Claim
29 words
The method of claim 2 wherein the decomposable organic material is a hydrocarbon which thermally decomposes to produce carbon at a temperature of from about 800° to 1200° C.
Claim 7
Dependent Claim
25 words
The method of claim 5 wherein the decomposable organic material is selected from the group consisting of phenol and furan resins and natural organic polymers.
Claim 8
Dependent Claim
11 words
The method of claim 6 wherein the substrate is quartz glass.
Claim 9
Dependent Claim
24 words
The method of claim 7 wherein said decomposable organic material is dissolved in a solvent selected from the group consisting of alcohols and ketones.
Claim 10
Dependent Claim
32 words
The method of claim 1 and further comprising the step of forming a photomask by removing select portions of the light-blocking layer to thereby provide a patterned carbon layer on said substrate.
Claim 11
Dependent Claim
34 words
The method of claim 9 wherein portions of the light-blocking layer are removed by selectively heating the portion of the carbon layer that is to be removed in the presence of an oxidizing atmosphere.
Claim 12
Dependent Claim
15 words
The method of claim 10 wherein said selective heating is carried out with a laser.
Claim 13
Dependent Claim
34 words
The method of claim 1 further comprising the step of repairing any defects in the carbon layer by selectively heating the layer in the defective areas and in the presence of a reducing atmosphere.
Claim 14
Dependent Claim
21 words
The method of claim 12 wherein said selective heating is carried out by directing a laser beam at the defective areas.
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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) | 1990-11-02 | 1991-05-04 | 1991-11-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-11-02 | 1995-05-04 | 1995-11-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-11-02 | 1999-05-04 | 1999-11-03 | $7700.00 | Window Closed / Lapsed |