Patent ID: 8701052

Claim:
A method of optical proximity correction (OPC), comprising: providing a layout pattern to a computer system; classifying the layout pattern into at least a first sub-layout pattern and at least a second sub-layout pattern; respectively performing at least an OPC calculation on the first sub-layout pattern and the second sub-layout pattern to form a corrected first sub-layout pattern and a corrected second sub-layout pattern; comparing the corrected first sub-layout pattern with the layout pattern to select a part of the corrected first sub-layout pattern as a first selected pattern; altering the first selected pattern to modify the corrected first sub-layout pattern as a third sub-layout pattern; comparing the corrected second sub-layout pattern with the layout pattern to select a part of the corrected second sub-layout pattern as a second selected pattern; altering the second selected pattern to modify the corrected second sub-layout pattern as a fourth sub-layout pattern; and respectively outputting the third sub-layout pattern onto a first mask and the fourth sub-layout pattern onto a second mask through the computer system.