Thermal stability on Mo/B 4 C multilayers

Abstract

Temperature stability of Mo/B4C multilayers with normal incidence peak reflectivity at 7 nm was investigated in a temperature range between 100°C and 900°C. With this multilayer pair we achieved up to 24% reflectivity in the asdeposited state at 6.7 nm. We investigated the effect of post-deposition annealing temperature and time on intrinsic stress, period and normal incidence reflectivity. We observed that stress alters almost linearly with temperature up to 600°C. In this temperature range the multilayer period expands by <1%. The major change in stress and period occurs in the first minutes of heat treatment. The stress relaxation is accompanied with volume and packing density increase (period expansion). This process, which happens within minutes, is followed by a diffusion controlled process.