Patent ID: 8142960

Claim:
A mask data producing method used in manufacturing a mask, the mask being irradiated with light emitted from a secondary light source during an exposure process, images of a first mask pattern and a second mask pattern being projected onto a photoresist of a wafer through a projection lens, the first mask pattern and the second mask pattern being formed in the mask, a lower-layer film material and the photoresist being laminated on the wafer, comprising: obtaining a first position of the wafer and a second position of the wafer using film thicknesses and optical characteristics of the photoresist and the lower-layer film material, shape of the secondary light source, and predetermined aberration of the projection lens, the first position of the wafer becoming a best focus for the first mask pattern, the second position of the wafer becoming a best focus for the second mask pattern; adjusting the aberration such that a difference between the first position and the second position falls within a predetermined range; and performing an OPC process using the adjusted aberration.