MIRROR FOR AN ILLUMINATION OPTICAL UNIT OF A PROJECTION EXPOSURE APPARATUS COMPRISING A SPECTRAL FILTER IN THE FORM OF A GRATING STRUCTURE AND METHOD FOR PRODUCING A SPECTRAL FILTER IN THE FORM OF A GRATING STRUCTURE ON A MIRROR

摘要

A mirror for an illumination optical unit (4) of a projection exposure apparatus (1) comprises a spectral filter in the form of a grating structure (30), wherein the grating structure (30) has a maximum edge steepness (b) in the range of 15° to 60°.