Abstract

Sandia National Laboratories is designing the illuminator for a soft-x-ray projection lithography system,^1,2,3 (see figure) using incoherent, 14-nm wavelength radiation generated by a laser-plasma source. The condenser optic is an off-axis elliptical mirror arranged to give Kohler illumination. The system that images the mask onto the wafer is an off-axis section of a Schwarzchild reflective microscope. As we design the illuminator, we need to be able to calculate its effects on the image quality of the whole system; this includes partial coherence effects, mirror surface quality, alignment and focusing, and source variations. In this paper, we discuss the detailed diffraction analysis that we are performing for this purpose and a few of our results.

© 1992 Optical Society of America