Index of Retraction and its Temperature Dependence of Calcium Fluoride Near 157nm
John H. Burnett, Ulf Griesmann, R Gupta, T E. Jou
We have made accurate measurements near 157 nm of the relative index of refraction, its dispersion, and its temperature dependence for two grades of calcium fluoride in N2 gas. Accurate measurements of the quantitites are needed for the design of lens systems for 157 nm F2 excimer-laser based exposure tools for photolithography. These optical properties were measured with precision goniometers on prisms of the materials in a N2 atmosphere using the minimum deviation method. The dispersion was determined using line emission radiation from a deuterium lamp at several wavelengths near 157 nm. Values of the relative refractive index fro two grades of calcium fluoride in N2 gas corrected to a temperature of 20 C and a pressure of one standard atmosphere are well within our 7 ppm estimated uncertainly for the measurements. The temperature of the samples and the surrounding medium were controlled to 0.05 C, which enabled accurate measurements of the temperature dependencies of the indices around room temperature near 157 nm.
International Symposium on Microelectronics
157nm, C<sub>a</sub>F<sub>2</sub> calcium fluoride, index of refraction, refractive index
, Griesmann, U.
, Gupta, R.
and Jou, T.
Index of Retraction and its Temperature Dependence of Calcium Fluoride Near 157nm, International Symposium on Microelectronics
(Accessed December 1, 2023)