Writing pattern producing method, photomask manufacturing method, and semiconductor device manufacturing method

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 a width of an overlapping portion of first and second patterns on the basis of pattern data for a mask pattern;
• determining whether the width of the overlapping portion is greater than a predetermined width;
• producing 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 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 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.