Patent ID: 8640058

Claim:
A computer-implemented method of decomposing a target pattern having features to be imaged on a substrate so as to allow the features to be imaged in a multi-exposure process, the method comprising the steps of: (a) segmenting a plurality of the features into a plurality of polygons; (b) generating, using a computer, a first interference map corresponding to the target pattern using a first one of the plurality of polygons and a function representing an illumination system for the multi-exposure process; (c) generating, using the computer, a second interference map corresponding to the target pattern using a second one of the plurality of polygons and the function representing the illumination system for the multi-exposure process; (d) combining the first and second interference maps to obtain a total interference map corresponding to the target pattern; and (e) assigning a phase to the plurality of polygons based on values of the total interference map at locations respectively corresponding to the polygons, the phase defining which exposure in the multi-exposure process the polygons are assigned.