International Sematech has awarded a contract to Optical Research Associates to develop its Code V optical design software to advance 157-nm microlithography system modeling.The project will provide new computer models for birefringent crystalline materials. Existing software simulates uniaxial birefringent crystals and symmetric, stress-induced birefringence.The enhanced software will simulate the inherent behavior of transmissive optical materials such as calcium fluoride, which show multiaxial, angle-dependent birefringence effects at 157 nm.The high performance demanded of 157-nm microlithography systems requires this increased modeling accuracy.