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John H. Burnett, Zachary H. Levine, Eric L. Shirley
Abstract
We discuss the intrinsic birefringence of calcium fluoride and othercrystalline materials that may be used in the optics for 193nm and 157nmlithography, including the characterization of the effect and itsimplications for performance of lens systems at these wavelengths. Wediscuss and assess the approaches by the lithography systems designers todeal with the effect.