Patent EP0532040A1 successfully refreshed from Google Patents.
EP0532040A1
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Discrete phase shift mask writing
Assignee: Applied Materials Inc
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Filing: 1992-09-11
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Granted: —
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Expires: 2012-09-11
Abstract
Abstract A method and apparatus for photolithographically fabricating features on a very large scale integrated circuit wafer by use of a phase shift mask defining discrete regions. This overcomes the problems of intensity nulls at the junction of regions formed by portions of the mask having opposite phase. The mask includes a transition region defining three phases which are assigned to pixels in the transition region, such that the phase assignment of the pixels is synthesized from an algorithm taking into account optical resolution and depth of focus. Each pixel is assigned one of three discrete phases, which thereby creates a transition region simulating a ramp between the two regions of opposite phases, such that intensity variation of the optical image corresponding to the transition region is minimized.
Inventors
- 👤 Andrew Muray, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 05:06
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/26; G03F1/28
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
93 words
A phase shift mask for lithography for defining a transition region between a first and a second region of respectively two different first and second phases, the mask also defining at least a third phase and comprising: a first portion of the transition region adjacent the first region being composed mostly of subregions of the first phase and partly of subregions of the third phase; and a second portion of the transition adjacent the second region being composed mostly of subregions of the second phase and partly of subregions of the third phase.
Claim 2
Dependent Claim
10 words
The mask of Claim 1 wherein each subregion is rectangular.
Claim 3
Dependent Claim
20 words
The mask of Claim 1 wherein the third phase includes a complex optical component relative to the first two phases.
Claim 4
Dependent Claim
15 words
The mask of Claim 1 wherein each subregion is formed of at least one pixel.
Claim 5
Dependent Claim
39 words
The mask of Claim 1 wherein the width of each subregion is equal to approximately 1/5th of the wave length of incident light for the photolithography divided by the numeric aperture of an imaging system used for the lithography.
Claim 6
Dependent Claim
13 words
The mask of Claim 1 wherein the subregions are of close packing shape.
Claim 7
Dependent Claim
39 words
The mask of Claim 1 wherein the first phase is defined by the presence of a phase shifter layer and the second phase is defined by the absence of a phase shifter layer on a substrate of the mask.
Claim 8
Dependent Claim
50 words
The mask of Claim 4, wherein the pixels are arranged in rows and columns, the columns being arranged along an axis defined by a length of the transition region, and the pixels in each row are arranged in terms of phase assignment symmetrically about a centerline of the transition region.
Claim 9
Dependent Claim
34 words
The mask of Claim 8, wherein the phase assignment of pixels in each row is an approximately linear function of a distance of the row from either the first region or the second region.
Claim 10
Dependent Claim
22 words
The mask of Claim 1, wherein the transition region differs in width by about 20% from the width of the first region.
Claim 11
Dependent Claim
56 words
A method of lithographically forming features on a substrate using the mask of Claim 1 and comprising the steps of: providing the mask of Claim 1; lithographically defining features on the substrate by passing radiation through the mask onto a substrate having a sensitive layer on its surface; and forming the defined features in the substrate.
Claim 12
Independent Claim
76 words
A method of lithographically forming features on a substrate using a mask and comprising the steps of: providing the mask for defining at least one transition region between two regions of differing phase, a region of the mask simulating a ramp between the two regions; lithographically defining features on a sensitive layer formed on a surface of the substrate by passing radiation through the mask onto the layer; and etching the defined features into the substrate.
Claim 13
Independent Claim
115 words
A method of making a phase shift mask comprising the steps of: providing a substrate; forming a resist layer on the substrate; exposing a plurality of pixels on the resist layer defining a transition region between a first and a second region of opposite first and second phases on the mask, the mask also defining at least a third phase, wherein a first portion of the transition region is composed mostly of pixels of the first phase and partly of pixels of the third phase, and a second portion of the transition region is composed mostly of pixels of the second phase and partly of pixels of the third phase; and developing the resist layer.
References Cited (Backward Citations)
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