ILLUMINATION SYSTEM FOR A MICROLITHOGRAPHIC PROJECTION EXPOSURE APPARATUS

摘要

An Illumination system for a microlithographic projection expose apparatus has a light source (14) and a first optical raster element (18; 118; 218) that is positioned in or in close proximity to a first plane (24). The first plane is conjugated to a pupil plane (28) of the illumination system (10) by Fourier transformation. A second optical raster (30; 130; 230) element is positioned in or in close proximity to the pupil plane (28). A third optical raster (36; 136; 236) element is positioned in or in close proximity to a second plane (34) that is also con jugated to the pupil plane (28) by Fourier transformation. The third optical raster element (36; 136; 236), which can be a diffractive optical element, introduces an additional degree of design freedom for the modification of the angular distribution of the projection light bundle.