Patent ID: 8112725

Claim:
A writing pattern producing method for writing on a photomask a mask pattern used for forming a circuit pattern on a semiconductor substrate, comprising: obtaining, by a computer, a width of an overlapping portion of first and second patterns on the basis of pattern data for a mask pattern; determining, by a computer, whether the width of the overlapping portion is greater than a predetermined width; producing, by a computer, a writing pattern according to a first method when the width of the overlapping portion is determined to be greater than the predetermined width; producing, by a computer, a writing pattern according to a second method when the width of the overlapping portion is determined to be smaller than the predetermined width; and producing, by a computer, a writing pattern according to either of the first and second methods when the width of the overlapping portion is determined to be equal to the predetermined width, the first method being to produce the writing pattern by dividing a composite pattern of the first and second patterns into a plurality of graphic forms which have widths not smaller than the predetermined width and do not overlap with one another, and the second method being to produce the writing pattern from the first and second patterns so that the overlapping portion is written repeatedly.