Optical analysis of mirror-based pattern generation

Abstract

We study mirror based pattern generation systems to provide an understanding of how they can be operated in an analog mode to meet the quasi-continuous sizing and placement requirements of optical lithography. Both tilting mirrors and piston-motion mirrors are examined. The aerial images are compared with those generated by simple binary masks. The effect of grayscaling, used to place and size features, on image quality is measured. Normalized image log slope (NILS) is used as the measure of image quality. Tilting mirrors used in grayscale mode provide image quality comparable to binary masks, and piston mirrors are somewhat better.