Lithographic processing method, and device manufactured thereby
View Patent ↗A method of splitting a lithographic pattern into two sub-patterns, includes generating test structures corresponding to structures of interest in the lithographic pattern, varying the test structures through a selected range of dimensions, simulating an image of the test structures, determining an image quality metric for the simulated image, analyzing the determined image quality metric to determine pitch ranges for which split improves the image quality metric and ranges for which split does not improve the image quality metric, and generating the two sub-patterns in accordance with the determined pitch ranges.
1. A method of splitting a lithographic pattern into a plurality of sub-patterns, comprising:
generating at least one test structure corresponding to one or more structures of interest in the lithographic pattern;
varying the at least one test structure through a selected range of dimensions to produce a plurality of varied test structures;
determining a plurality of values for an image quality metric for images of the plurality of varied test structures;
analyzing the plurality of values to determine ranges of dimensions for which a pattern split would improve the value of the image quality metric; and
splitting the lithographic pattern into the plurality of sub-patterns of the lithographic pattern in accordance with the determined ranges.
2. A method as in claim 1 , wherein the images comprise simulated images.
3. A method as in claim 1 , further comprising:
determining the value of a sub-pattern image quality metric for an image of each of the sub-patterns;
comparing the value of the sub-pattern image quality metric for the sub-patterns with the value of the image quality metric for the image; and
based on the comparing, determining whether the sub-patterns result in an improvement of the value of the image quality metric.
4. A method as in claim 1 , wherein the ranges of dimensions comprises dimensions that are selected from the group consisting of: pitch, line to line, end to end, end to line and corner to corner.
5. A method as in claim 1 , wherein the determining the value of the image quality metric comprises determining a value of the image quality metric at a plurality of locations within the image.
6. A method as in claim 1 , wherein the plurality of locations includes locations including to a plurality of different types of dimensions and the method further comprises assigning a selected priority between types.
7. A method as in claim 1 , wherein the generated sub-patterns further comprise added assist features not present in the lithographic pattern.
8. A method as in claim 7 , wherein the assist features comprise sub-resolution features.