Patent ID: 8910091

Claim:
A computer-implemented method, comprising: identifying a target pattern having features to be printed in a single layer of an integrated circuit device; defining data for a first mask for use with a first exposure in a multiple-exposure lithographic imaging process; defining data for a second mask for use with a second exposure in the multiple-exposure lithographic imaging process; modifying the data for the first and second masks for respectively causing portions of the target pattern to be imaged during the first and second exposures; determining a critical dimension value for features based on certain aspects of the multiple-exposure lithographic imaging process; identifying first and second critical features in the modified first and second masks that have dimensions less than the determined critical dimension value; determining first and second properties of transmissive mask material to be included in the modified first and second masks, respectively, for the first and second critical features; determining, using lithographic models and a computer, an amount of chrome shielding to include in the modified first and second masks; and determining, using image simulation by the computer based on the modified first and second masks, a size of scattering bars that can be included in the first and second masks, wherein the image simulation takes into account mutual trimming by a background exposure of the first and second exposures.