Optical constants of beryllium thin layers determined from Mo/Be multilayers in spectral range 90 to 134 eV

Mewael Giday Sertsu, Andrey Sokolov, Nikolay Chkhalo, Vladimir Polkovnikov, Nikolay Salashchenko, Mikhail Svechnikov, Franz Schäfers
2021 Optical Engineering: The Journal of SPIE  
Mo/Be multilayers are promising optical elements for extreme ultraviolet (EUV) lithography and space optics. Experimentally derived optical constants are necessary for accurate and reliable design of beryllium-containing optical coatings. We report optical constants of beryllium derived from synchrotron radiation-based reflectivity data of Mo/Be multilayers. Results are in good agreement with available data in the literature obtained from the well-known absorption measurements of beryllium thin
more » ... s of beryllium thin films or foils. We demonstrate synchrotron based at-wavelength reflectometry as an accurate and non-destructive technique for deriving EUV optical constants for materials that are difficult or unstable to make thin foils for absorption measurements.
doi:10.1117/1.oe.60.4.044103 fatcat:x5f6egg3i5d3bmhjejiheihaui