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Reflective optical imaging system with balanced distortion

United States Patent

5,973,826
October 26, 1999
View the Complete Patent at the US Patent & Trademark Office
Lawrence Livermore National Laboratory - Visit the Industrial Partnerships Office Website
An optical system compatible with short wavelength (extreme ultraviolet) An optical system compatible with short wavelength (extreme ultraviolet) radiation comprising four reflective elements for projecting a mask image onto a substrate. The four optical elements comprise, in order from object to image, convex, concave, convex and concave mirrors. The optical system is particularly suited for step and scan lithography methods. The invention enables the use of larger slit dimensions associated with ring field scanning optics, improves wafer throughput and allows higher semiconductor device density. The inventive optical system is characterized by reduced dynamic distortion because the static distortion is balanced across the slit width.
Chapman; Henry N. (Sunol, CA), Hudyma; Russell M. (San Ramon, CA), Shafer; David R. (Fairfield, CT), Sweeney; Donald W. (San Ramon, CA)
Regents of the University of California (Oakland, CA)
09/ 027,281
February 20, 1998
The United States Government has rights in this invention pursuant to Contract No. W-7405-ENG-48 between the U.S. Department of Energy and the University of California, for the operation of Lawrence Livermore National Laboratory.