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US 7,600,212 B2Granted
Method of compensating photomask data for the effects of etch and lithography processes
AssigneeCadence Design Systems, Inc.
InventorsFranz X. Zach, Jesus Carrero, Bayram Yenikaya, Gokhan Percin, Xuelong Cao, Abdurrahman Sezginer
Life of this patent
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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.
Claims55
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.
2 more elements
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;
- 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.
6 more elements
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 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.
2 more elements
A computer readable medium comprising computer executable instructions to cause a computer to:
- 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.
2 more elements
A computer readable medium comprising computer executable instructions to cause a computer to:
- 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.
6 more elements
A computer readable medium comprising computer executable instructions to cause a computer to:
- 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.
2 more elements
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.
6 more elements
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.
10 more elements
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.
6 more elements
Dependencies are inferred from the claim text.