Enhanced reflectivity and stability of Sc/Si multilayers

Abstract

Sc/Si multilayers were designed for normal incidence reflectivity in the wavelength range from 35 to 50 nm and were deposited by dc-magnetron sputtering. X-ray scattering of CuKα radiation, transmission electron microscopy, atomic force microscopy and chemical analysis were used for the characterization of the multilayer structures. The normal incidence reflectivity was measured as a function of the wavelength, for different layer thickness ratios, number of layers and some important sputter parameters. Maximum reflectivities of 21% @ 38 nm and 54 % @ 46 nm for Sc/Si multilayer mirrors were achieved. Reflectivity up to 56 % @ 44.7 nm for a Sc/Si multilayers having enhanced interface structure due to Cr diffusion barriers will be under discussion. The increase in reflectivity is consistent with multilayers having sharper and smoother interfaces. The evolutions of optical properties in the temperature range from 50°C to 250°C for classical Sc/Si and interface engineered Sc/Cr/Si/Cr multilayers will be compared.