Patent ID: 6993741

Claim:
A method of generating patterns of a paired set of photomasks from a data set defining a circuit layout to be provided on a substrate, comprising: inputting a circuit layout; identifying critical segments of said circuit layout; generating and legalizing block mask patterns based on said identified critical segments; and generating, legalizing and coloring phase mask patterns for use in a dual exposure method with said legalized block mask patterns, said phase mask patterns including pairs of juxtaposed etched regions in said phase mask, each region of each said pair having a pathlength difference of an odd number of half wavelengths relative to the other region of each said pair, wherein said legalized block mask patterns define a block mask and said colored legalized phase mask patterns define an alternating phase shift mask, said block mask and said alternating phase shift mask operable to be used together in a dual exposure method for patterning critical dimensioned features on said substrate.