Patent ID: 7493589

Claim:
A method of decomposing a target pattern having features to be imaged on a substrate so as to allow said features to be imaged in a multi-exposure process, said method comprising the steps of: (a) segmenting a plurality of said features into a plurality of polygons; (b) determining the image log slope (ILS) value for each of said plurality of polygons; (c) determining the polygon having the minimum ILS value, and defining a mask containing said polygon; (d) convolving said mask defined in step (c) with an eigen function of a transmission cross coefficient so as to generate a first interference map, said transmission cross coefficient defining an illumination system; and (e) assigning a phase to said polygons based on the value of the first interference map at a location respectively corresponding to said polygons, said phase defining which exposure in said multi-exposure process said polygons are assigned.