Patent ID: 7386830

Claim:
A computer implemented method for designing an illumination light source, comprising: acquiring a control feature configured to control a dimension of a transferred pattern of a mask pattern; designating a plurality of illumination elements illuminating the mask pattern; designating first illumination lights to each of first polarization states of a light emitted from each of the illumination elements; calculating a first optical image of the control feature, the first optical image formed on a first imaging plane by each of the first illumination lights, the first imaging plane being a best focus plane; determining optimal polarization states of the first illumination lights from among the first polarization states, based on an optical characteristic of the first optical image; calculating a second optical image of the control feature, the second optical image formed on a second imaging plane by each of the first illumination lights, the second imaging plane being a defocus plane; and determining an illumination shape and a polarization state distribution of the light, based on optical characteristics of the first and second optical images and the optimal polarization states.