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Proceedings Paper

Index of refraction and its temperature dependence of calcium fluoride near 157 nm
Author(s): John H. Burnett; Rajeev Gupta; Ulf Griesmann; Ted E. Jou
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Paper Abstract

We have made accurate measurement 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 these quantities are needed for the design of lens system for 157 nm F2 excimer-laser-based exposure tools for photolithography. These optical properties were measured with precision goniometer 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 for two grades of calcium fluoride in N2 gas corrected to a temperature of 20 degrees C and a pressure of one standard atmosphere are well within our 7 ppm estimated uncertainty forth measurements. The temperature of the samples and the surrounding medium were controlled to 0.05 degrees C, which enabled accurate measurements of the temperature dependencies of the indices around room temperature near 157 nm.

Paper Details

Date Published: 26 July 1999
PDF: 7 pages
Proc. SPIE 3679, Optical Microlithography XII, (26 July 1999); doi: 10.1117/12.354324
Show Author Affiliations
John H. Burnett, National Institute of Standards and Technology (United States)
Rajeev Gupta, National Institute of Standards and Technology (United States)
Ulf Griesmann, National Institute of Standards and Technology (United States)
Ted E. Jou, National Institute of Standards and Technology (United States)


Published in SPIE Proceedings Vol. 3679:
Optical Microlithography XII
Luc Van den Hove, Editor(s)

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