Critical illumination condenser for extreme ultraviolet projection lithography

摘要

A condenser system couples a radiation source to an imaging system. The authors have designed a critical illumination condenser system which meets the technical challenges of extreme ultraviolet projection lithography based on a ring field imaging system and a laser produced plasma source. The optical system, a three spherical mirror optical design, is capable of illuminating the extent of the mask plane by scanning either the primary mirror or the laser plasma source. This type of condenser optical design is sufficiently versatile to be employed with two distinct systems, one from Lawrence Livermore National Laboratory and one from AT and T/Sandia.