Patent ID: 8122391

Claim:
A computer-implemented method of generating complementary masks based on a target pattern having features to be imaged on a substrate, said complementary masks for use in a multiple-exposure lithographic imaging process using at least first and second different illumination settings, respectively, said method comprising the steps of: defining an initial H-mask corresponding to said target pattern for use with the first illumination setting; defining an initial V-mask corresponding to said target pattern for use with the second illumination setting; identifying horizontal edges of certain first features in both said H-mask and said V-mask; identifying vertical edges of certain second features in both said V-mask and said H-mask; assigning a first transmissive mask material to print said certain first features using said H-mask; assigning a second transmissive mask material to print said certain second features using said V-mask; and determining, using OPC models run by a computer, first and second scattering bars to apply to the H-mask and V-mask, respectively, wherein the determination of the scattering bars to apply includes determining, using the OPC models, a relative placement and a relative orientation of the first and second scattering bars that will cause complete mutual trimming of both of the first and second scattering bars when the modified H-mask and V-mask are used in the multiple-exposure lithographic imaging process, and wherein the determination of the scattering bars to apply includes permitting a size of the scattering bars to be larger than a printable size, and wherein printing of the scattering bars is prevented by a background exposure of each exposure in the lithographic imaging process.