Optical properties of fluids for 248 and 193 nm immersion photolithography

We present measured values of the refractive index, thermo-optic coefficient, and absorption coefficient of a number of common organic solvents and aqueous inorganic solutions that may have application in immersion photolithography at 248 or 193 nm wavelengths. The measurements were performed with a laser-based Hilger-Chance refractometer system whose design and operation are described. The optical properties of the sample fluids are compared with those of water, the currently favored immersion medium, and we discuss the potential for finding higher-index fluids that will be suitable for this application.