Computer readable storage medium storing program for generating reticle data, and method of generating reticle data

A computer readable storage medium stores a program for generating reticle data for producing a reticle used in an exposure apparatus, the program including the steps of classifying target patterns to be formed on a substrate into a plurality of direction groups, extracting, for each of the plurality of direction groups, a region suited to resolution of a target pattern belonging to the direction group from an effective light source distribution formed on a pupil of a projection optical system by an illumination optical system, thereby determining the extracted region as a partial light source, executing, for each of a plurality of partial light sources determined in the step of extracting a region, processing of determining a pattern to be placed on a reticle when each partial light source is used as an illumination condition, and merging patterns determined in the step of executing processing.