Masks that include
optical proximity correction or phase shifting regions are increasingly being used in the manufacturing process. These masks, either initially or after repair, can have “soft” defects, e.g. phase and / or transmission defects. In accordance with one feature of the invention, soft defect information can be computed from
standard test images of a
mask. This soft defect information can be used to generate an accurate simulated
wafer image, thereby providing valuable defect
impact information to a user. Knowing the
impact of the soft defect can enable a user to make better decisions regarding the
mask. Specifically, a user can now with confidence accept the
mask for the desired lithographic process, repair the mask at certain critical locations, or reject the mask, all without exposing a
wafer.