Mask pattern generation method

A method for generating a pattern of a mask used for exposing a substrate, the method comprising the following steps performed by a processor,

• obtaining data of a plurality of polygons representing a plurality of pattern elements,
• grouping polygons which overlap or contact with each other among the plural polygons in one group, not setting an evaluation position for evaluating an image of a pattern of the one group on a line segment of sides which overlap or contact with each other among sides of the polygon of the one group, and setting an evaluation position at a portion except for the line segment,
• repeating calculating the image of the pattern of the one group, evaluating the calculated image at the set evaluation position, and correcting the pattern based on a result of the evaluating, and
• generating the pattern of the mask based on a result of the repeating.