Method of compensating photomask data for the effects of etch and lithography processes
First Claim
Patent Images
1. A method of synthesizing a photomask data set from a given target layout, comprising the steps of:
- a) providing a set of target polygons for said target layout;
b) fitting a smooth curve to a target polygon of said set of target polygons by a computer, the curve having a set of etch-target points;
c) moving the etch target points according to a model of an etch process to produce a set of lithography-target points, wherein said model of an etch process comprises calculating how much of a region above a wafer is visible from a point on the sidewall of an etched feature in the wafer; and
d) synthesizing a photomask data set based on a model of a lithography process and the set of lithography-target points.
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Abstract
A method for synthesizing a photomask data set from a given target layout, including the following steps: (a) providing a set of target polygons for the target layout; (b) fitting a smooth curve to a target polygon of the set of target polygons, the curve having a set of etch-target points; (c) moving the etch target points according to a model of an etch process to produce a set of lithography-target points; and (d) synthesizing a photomask data set based on a model of a lithography process and the set of lithography-target points.
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Citations
55 Claims
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1. A method of synthesizing a photomask data set from a given target layout, comprising the steps of:
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a) providing a set of target polygons for said target layout; b) fitting a smooth curve to a target polygon of said set of target polygons by a computer, the curve having a set of etch-target points; c) moving the etch target points according to a model of an etch process to produce a set of lithography-target points, wherein said model of an etch process comprises calculating how much of a region above a wafer is visible from a point on the sidewall of an etched feature in the wafer; and d) synthesizing a photomask data set based on a model of a lithography process and the set of lithography-target points. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of synthesizing a photomask data set from a given target layout, comprising the steps of:
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a) providing a set of target polygons for said target layout; b) fitting a smooth curve to a target polygon of said set of target polygons by a computer, the curve having a set of etch-target points; c) moving the etch target points according to a model of an etch process to produce a set of lithography-target points; and d) synthesizing a photomask data set based on a model of a lithography process and the set of lithography-target points and wherein synthesizing a photomask data set further comprises; calculating an image intensity at a plurality of lithography target points according to the model of the lithography process; calculating a figure-of-demerit comprising a sum of differences between the calculated image intensities and predetermined values, wherein the sum is evaluated over said plurality of lithography target points; and adjusting the photomask data in a way that decreases the said figure-of-demerit. - View Dependent Claims (16, 17, 18, 19)
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20. A method of synthesizing a photomask data set from a given target layout, comprising the steps of:
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a) providing a set of target polygons for said target layout; b) fitting a smooth curve to a target polygon of said set of target polygons by a computer, the curve having a set of etch-target points; c) moving the etch target points according to a model of an etch process to produce a set of lithography-target points, wherein said model of an etch process comprises includes calculating a convolution of a point-spread-function with a photoresist pattern density; and d) synthesizing a photomask data set based on a model of a lithography process and the set of lithography-target points. - View Dependent Claims (21)
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22. A computer readable medium comprising computer executable instructions to cause a computer to:
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a) provide a set of target polygons for said target layout; b) fit a smooth curve to a target polygon of said set of target polygons, the curve having a set of etch-target points; c) move the etch target points according to a model of an etch process to produce a set of lithography-target points, wherein said model of an etch process comprises calculating how much of a region above a wafer is visible from a point on the sidewall of an etched feature in the wafer; and d) synthesize a photomask data set based on a model of a lithography process and the set of lithography-target points. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. A computer readable medium comprising computer executable instructions to cause a computer to:
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a) provide a set of target polygons for said target layout; b) fit a smooth curve to a target polygon of said set of target polygons, the curve having a set of etch-target points; c) move the etch target points according to a model of an etch process to produce a set of lithography-target points; and d) synthesize a photomask data set based on a model of a lithography process and the set of lithography-target points and wherein synthesizing a photomask data set further comprises; calculating an image intensity at a plurality of lithography target points according to the model of the lithography process; calculating a figure-of-demerit comprising a sum of differences between the calculated image intensities and predetermined values, wherein the sum is evaluated over said plurality of lithography target points; and adjusting the photomask data in a way that decreases the said figure-of-demerit. - View Dependent Claims (35, 36, 37)
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38. A computer readable medium comprising computer executable instructions to cause a computer to:
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a) provide a set of target polygons for said target layout; b) fit a smooth curve to a target polygon of said set of target polygons, the curve having a set of etch-target points; c) move the etch target points according to a model of an etch process to produce a set of lithography-target points, wherein said model of an etch process comprises includes calculating a convolution of a point-spread-function with a photoresist pattern density; and d) synthesize a photomask data set based on a model of a lithography process and the set of lithography-target points.
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39. A computer-aided design apparatus configured to synthesize a photomask data set from a given target layout, comprising
a processor; -
a memory connected to the processor; and a computer readable medium having instructions embedded therein, the instructions configured to cause the processor to perform the operations of; a) providing a set of target polygons for said target layout; b) fitting a smooth curve to a target polygon of said set of target polygons, the curve having a set of etch-target points; c) moving the etch target points according to a model of an etch process to produce a set of lithography-target points, wherein said model of an etch process comprises calculating how much of a region above a wafer is visible from a point on the sidewall of an etched feature in the wafer; and d) synthesizing a photomask data set based on a model of a lithography process and the set of lithography-target points. - View Dependent Claims (40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50)
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51. A computer-aided design apparatus configured to synthesize a photomask data set from a given target layout, comprising
a processor; -
a memory connected to the processor; and a computer readable medium having instructions embedded therein, the instructions configured to cause the processor to perform the operations of; a) providing a set of target polygons for said target layout; b) fitting a smooth curve to a target polygon of said set of target polygons, the curve having a set of etch-target points; c) moving the etch target points according to a model of an etch process to produce a set of lithography-target points; and d) synthesizing a photomask data set based on a model of a lithography process and the set of lithography-target points and wherein synthesizing a photomask data set further comprises; calculating an image intensity at a plurality of lithography target points according to the model of the lithography process; calculating a figure-of-demerit comprising a sum of differences between the calculated image intensities and predetermined values, wherein the sum is evaluated over said plurality of lithography target points; and adjusting the photomask data in a way that decreases the said figure-of-demerit. - View Dependent Claims (52, 53, 54)
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55. A computer-aided design apparatus configured to synthesize a photomask data set from a given target layout, comprising
a processor; -
a memory connected to the processor; and a computer readable medium having instructions embedded therein, the instructions configured to cause the processor to perform the operations of; a) providing a set of target polygons for said target layout; b) fitting a smooth curve to a target polygon of said set of target polygons, the curve having a set of etch-target points; c) moving the etch target points according to a model of an etch process to produce a set of lithography-target points, wherein said model of an etch process comprises includes calculating a convolution of a point-spread-function with a photoresist pattern density; and d) synthesizing a photomask data set based on a model of a lithography process and the set of lithography-target points.
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Specification