Mask pattern correction process, photomask and semiconductor integrated circuit device

Abstract

In order that CAD processing time required for modifying an input design pattern to compensate for optical proximity effects is reduced, increases in the number of base shapes when corrected data are converted into EB data are restricted, and false detection of defects in a photomask inspection process is restricted, the following steps are taken. At a shape selection step, rectangular shapes are divided into a dense rectangular shape group and a non-dense rectangular shape group according to the distance of each rectangular shape to an adjacent rectangular shape. At a number-of-shapeas comparison step, the number of shapes included in the dense rectangular shape group is compared to the number of shapes included in the non-dense rectangular shape group to select either shape group for correction. At a correction process selection step, a correction process suited for the selected shape group is selected. At a shape correction step, optical proximity correction is made. At a shape combining step, a group of corrected shapes and the rectangular shape group different from the selected one are combined.