METHOD OF IMAGING A MASK PATTERN ON A SUBSTRATE BY MEANS OF EUV RADIATION, AND APPARATUS AND MASK FOR PERFORMING THE METHOD

摘要

An EUV radiation source unit (10) for use in a lithographic projection apparatus to illuminate a mask pattern (22) which is to be projected on a substrate (W) comprises an electron source (12) and a medium in which the electrons of the source generate EUV Cherenkov radiation (PB). The wavelengths of the Cherenkov radiation and the multilayer structure of the mirrors (31-34) of the projection system (30) are adapted to each other, so that these mirrors show a maximum reflectivity. The medium forms part of the mask (MA) so that a mirror condenser system is no longer needed. In this way, an efficient transmission of radiation (PB) from the source to the substrate is obtained.