Mask illuminating method for microlithographic projection exposure system, involves determining intensity distribution such that lights in Y-direction and X-direction despite of anamorphic effect has same numerical apertures

摘要

The method involves arranging secondary light sources in a pupil surface. An object field on a mask (14) is imaged, where an optical element arranged between the sources and the mask has a different refractive power in a V-direction and an X-direction, and intensity distribution in the pupil surface has different dimensions along a Y-direction and the X-direction. The intensity distribution is determined in such a manner that lights in the Y-direction and the X-direction despite of an anamorphic effect of the element has same numerical apertures, where the lights are incident on the mask. An independent claim is also included for an illumination system of a microlithographic projection exposure system, comprising a lens.