Patent EP0090924A2 successfully refreshed from Google Patents.
EP0090924A2
Expired / Lapsed
EP
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Method of increasing the image resolution of a transmitting mask and improved masks for performing the method
Assignee: International Business Machines Corp
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Filing: 1983-02-08
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Granted: —
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Expires: 2003-02-08
Abstract
Abstract A mask (21) for use in photolithography with incident light which is at least partially coherent has a layer or zone of a transparent material (26) at every other transmitting region (24, 25) of the mask. The transparent material has an index of refraction n and a thickness d such that (n-1) d=Φλ where λ is the wave length of the incident light, and Φ is a fraction between 1/4 and 3/4. Graph (a) shows the amplitude of the electric vector of the emergent light at the mask and graph (b) that vector at the image plane. Graph (c) shows the light intensity at the image plane.
Inventors
- 👤 Marc David Levenson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 13:53
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/20; G03F7/2002; G03F1/00; G03F1/26; G03F1/30; G03F7/70; G03F7/70216; G03F7/70283
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
61 words
A method of improving the resolution of an image formed by projecting at least partially coherent light through a mask comprising opaque and transmitting zones, said method being characterised by establishing a phase difference between light beams passing through adjacent transmitting zones such that the image definition is enhanced by destructive interference between light diffracted at the two adjacent transmitting zones.
Claim 2
Independent Claim
61 words
A method of improving the resolution of an image formed by projecting at least partially coherent light through a mask comprising opaque and transmitting zones, said method being characterised by establishing a phase difference between light beams passing through adjacent transmitting zones such that the image definition is enhanced by destructive interference between light diffracted at the two adjacent transmitting zones.
Claim 3
Dependent Claim
40 words
A method as claimed in claim 1, further characterised in that the phase difference is established by coating alternate transmitting zones with a transmitting material having a refractive index different to that of the material in the intervening transmitting zones.
Claim 4
Dependent Claim
60 words
A mask for use in a method as claimed in claim 1 or 2, said mask comprising opaque and transmitting zones and being characterised in that alternate transmitting zones have different optical characteristics to those of the intervening zones such that at least some destructive interference occurs between light diffracted at adjacent transmitting zones and the image definition is enhanced.
Claim 5
Dependent Claim
42 words
A mask as claimed in claim 3, further characterised in that the different optical characteristics are introduced by covering the alternate transmitting zones with a transmitting material having a refractive index (n) different to that of the material in the intervening =ones.
Claim 6
Dependent Claim
43 words
A mask as claimed in claim 4, further characterised in that the transmitting material has thickness (d) such that (n-1)d= 0 Φλ where is the wavelength of the incident light and & is a fraction between one quarter (1/4) and three quarters (3/4).
Claim 7
Dependent Claim
16 words
A mask as claimed in claim 5, further characterised in that a is one half (1/2).
Claim 8
Dependent Claim
21 words
A mask as claimed in claim 4, 5 or 6, further characterised in that the transmitting material is a polymeric material.
Claim 9
Dependent Claim
17 words
A mask as claimed in claim 7, further characterised in that the transmitting material is poly(methyl methacrylate).
Claim 10
Dependent Claim
78 words
A mask for use in photolithography with incident light which is at least partially coherent, said mask comprising opaque regions and transmitting regions and characterized by the improvement according to which a transparent material is positioned over or under every other transmitting region, the transparent material having an index of refraction n and a thickness d such that (n-1)d=Φλ where λ is the wave length of the incident light and a is a fraction between 1/4 and 3/4.
Claim 11
Dependent Claim
78 words
A mask for use in photolithography with incident light which is at least partially coherent, said mask comprising opaque regions and transmitting regions and characterized by the improvement according to which a transparent material is positioned over or under every other transmitting region, the transparent material having an index of refraction n and a thickness d such that (n-1)d=Φλ where λ is the wave length of the incident light and a is a fraction between 1/4 and 3/4.
References Cited (Backward Citations)
No citation records indexed.
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