Patent ID: 7732107

Claim:
A method of correcting a mask pattern used in pattern transfer, onto a target object having a plurality of target regions for pattern transfer, of a photomask under light exposure repeated multiple number of times to thereby form a transferred pattern, comprising: calculating, for every single one of shot regions having a transferred pattern formed by a single time of light exposure through a mask pattern and every single one of a plurality of chip regions comprised in one of said shot regions, a numerical aperture of said mask pattern corresponding to said transferred pattern onto said target object based on an exposure layout of the plurality of shot regions while considering a first flare due to influence from the peripherals of said shot region and a second flare due to influence from the peripherals of said chip region; and calculating a dimension of said mask pattern necessary for obtaining said transferred pattern of a predetermined dimension, using said numerical aperture calculated in the above; wherein said calculating said numerical aperture calculates an average numerical aperture for a plurality of said shot regions and chip regions, corrects a design value of said numerical aperture for said shot regions and chip regions for the calculation using said average numerical aperture, and calculates an effective value of said numerical aperture for said shot regions and chip regions for the calculation.