US4842969A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transmittance modulation photomask, process for producing the same, and process for producing diffraction gratings using the same
Assignee: Kuraray Co Ltd
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Filing: 1987-12-01
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Granted: 1989-06-27
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Expires: 2007-12-01
Abstract
Abstract The present invention provides a process for producing a blazed diffraction grating by using a transmission modulation diffraction grating as a photomask in photolithography. The photomask is composed of a relief modulation diffraction grating (A) made of a transparent material and a blazed diffraction grating (B) made of a material containing a ray absorbing agent. The diffraction grating (A) and the diffraction grating (B) are mated with each other through their grating surfaces.
Inventors
- 👤 Nobuhiro Kawatsuki
- 👤 Katsuya Fujisawa
- 👤 Ichiro Matsuzaki
- 👤 Masao Uetsuki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 11:48
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/54; G03F7/00; G03F7/0005; G03F7/001; G02; G02B; G02B5/00; G02B5/18; G02B5/1847; G02B5/1857; G03F1/50; H; H10; H10P; H10P76/00
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
100 words
A transmittance modulation photomask which comprises: (a) a first blazed diffraction grating made of a transparent material and (b) a second blazed diffraction grating made of a material containing a ray absorbing agent, wherein: (c) said first diffraction grating and said second diffraction grating mate with each other at their respective grating surfaces; (d) the refractive index of the material constituting said first diffraction grating is at least approximately equal to the refractive index of the material constituting said second diffraction grating; and (e) the upper and lower surfaces of the photomask are at least approximately parallel to each other.
Claim 2
Dependent Claim
100 words
A transmittance modulation photomask which comprises: (a) a first blazed diffraction grating made of a transparent material and (b) a second blazed diffraction grating made of a material containing a ray absorbing agent, wherein: (c) said first diffraction grating and said second diffraction grating mate with each other at their respective grating surfaces; (d) the refractive index of the material constituting said first diffraction grating is at least approximately equal to the refractive index of the material constituting said second diffraction grating; and (e) the upper and lower surfaces of the photomask are at least approximately parallel to each other.
Claim 3
Dependent Claim
37 words
A photomask as claimed claim 1 wherein the difference between the refractive index of the material constituting said first diffraction grating and the refractive index of the material constituting said second diffraction grating is smaller than 0.01.
Claim 4
Dependent Claim
18 words
A photomask as claimed in claim 2 wherein the difference between the refractive indices is smaller than 0.001.
Claim 5
Dependent Claim
23 words
A photomask as claimed in claim 1 wherein the grating surfaces of said first and second diffraction gratings are serrate in cross section.
Claim 6
Dependent Claim
23 words
A photomask as claimed in claim 1 wherein the grating surfaces of said first and second diffraction gratings are curved in cross section.
Claim 7
Independent Claim
99 words
A method for producing a transmittance modulation photomask which comprises the steps of: (a) forming a first diffraction grating made of a transparent material and having a planar rear surface; (b) forming a second diffraction grating made of a material having at least approximately the same refractive index as the material of which said first diffraction grating is made, containing a ray absorbing agent, and having a planar rear surface; and (c) joining said first and second diffraction gratings at their respective diffraction surfaces such that their respective planar rear surfaces are at least approximately parallel to each other.
Claim 8
Independent Claim
99 words
A method for producing a transmittance modulation photomask which comprises the steps of: (a) forming a first diffraction grating made of a transparent material and having a planar rear surface; (b) forming a second diffraction grating made of a material having at least approximately the same refractive index as the material of which said first diffraction grating is made, containing a ray absorbing agent, and having a planar rear surface; and (c) joining said first and second diffraction gratings at their respective diffraction surfaces such that their respective planar rear surfaces are at least approximately parallel to each other.
Claim 9
Dependent Claim
41 words
A method for producing a photomask as claimed in claim 6 wherein the difference between refractive index of the material constituting said first diffraction grating and the refractive index of the material constituting said second diffraction grating is smaller than 0.01.
Claim 10
Dependent Claim
22 words
A method for producing a photomask as claimed in claim 7 wherein the difference between the diffractive indices is smaller than 0.001.
Claim 11
Dependent Claim
24 words
A method for producing a photomask as claimed in claim 6 wherein the grating surface on said first diffraction grating is formed by cutting.
Claim 12
Dependent Claim
24 words
A method for producing a photomask as claimed in claim 6 wherein the grating surface on said first diffraction grating is formed by photolithography.
Claim 13
Dependent Claim
34 words
A method for producing a photomask as claimed in claim 10 wherein the grating surface on said first diffraction grating is formed by drawing directly on a photoresist on the substrate by changing dose.
Claim 14
Dependent Claim
30 words
A method for producing a photomask as claimed in claim 10 wherein the grating surface on said first diffraction grating is formed directly by the asymmetric double-beam interference exposure method.
Claim 15
Dependent Claim
65 words
A method for producing a photomask as claimed in claim 6 wherein said first diffraction grating is formed by the steps of: (a) forming a layer of photosensitive resin on a substrate; (b) forming the grating surface on said photosensitive resin by exposure and photolithographic development; and (c) transferring the grating surface to the substrate by dry etching using said grating surface as a photomask.
Claim 16
Dependent Claim
25 words
A method for producing a photomask as claimed in claim 13 wherein the substrate is formed by coating a glass plate with a transparent material.
Claim 17
Dependent Claim
30 words
A method for producing a photomask as claimed in claim 13 wherein the substrate is formed by coating a glass plate with a transparent material containing a light absorbing agent.
Claim 18
Dependent Claim
20 words
A method for producing a photomask as claimed in claim 13 wherein the transfer is accomplished by oxygen plasma etching.
Claim 19
Dependent Claim
22 words
A method for producing a photomask as claimed in claim 16 wherein the light absorbing agent is an ultraviolet light absorbing agent.
References Cited (Backward Citations)
US3777633A
Cited
US4414317A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-06-26 | 1992-12-26 | 1993-06-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-06-26 | 1996-12-26 | 1997-06-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-06-26 | 2000-12-26 | 2001-06-27 | $7700.00 | Window Closed / Lapsed |