Patent ID: 8741507

Claim:
A method for separating photomask pattern, including the following steps: providing a layout pattern, wherein the layout pattern is defined with at least one critical region and at least one non-critical region, the critical region comprises a plurality of critical patterns, and the non-critical region comprises a plurality of non-critical patterns, wherein the distance between a critical pattern and any adjacent critical pattern is smaller than a critical dimension (CD), and the distance between a non-critical pattern and any adjacent non-critical pattern is larger than the critical dimension; performing a first split process to divide the critical patterns into a plurality of first patterns and a plurality of second patterns; performing a second split process to divide the non-critical patterns into a plurality of third patterns and a plurality of fourth patterns; and outputting the first patterns and the third patterns to a first photomask, and outputting the second patterns and the fourth patterns to a second photomask.