title: Mo/Si and Mo/Be multilayer thin films on Zerodur substrates for extreme-ultraviolet lithography.
abstract: Multilayer-coated Zerodur optics are expected to play a pivotal role in an extreme-ultraviolet (EUV) lithography tool. Zerodur is a multiphase, multicomponent material that is a much more complicated substrate than commonly used single-crystal Si or fused-silica substrates. We investigate the effect of Zerodur substrates on the performance of high-EUV reflectance Mo/Si and Mo/Be multilayer thin films. For Mo/Si the EUV reflectance had a nearly linear dependence on substrate roughness for roughness values of 0.06-0.36 nm rms, and the FWHM of the reflectance curves (spectral bandwidth) was essentially constant over this range. For Mo/Be the EUV reflectance was observed to decrease more steeply than Mo/Si for roughness values greater than approximately 0.2-0.3 nm. Little difference was observed in the EUV reflectivity of multilayer thin films deposited on different substrates as long as the substrate roughness values were similar.
authors.affiliation: Lawrence Livermore National Laboratory, Mail Stop L-395, 7000 East Avenue, Livermore, California 94550, USA. mirkarimi1@llnl.gov
authors.forename: P B
authors.initials: PB
authors.lastname: Mirkarimi
authors.forename: S
authors.initials: S
authors.lastname: Bajt
authors.forename: M A
authors.initials: MA
authors.lastname: Wall