Structural Relaxation and Phase Trans-formations in Silicon/Transition Metal Multilayers

Abstract

In this paper recent work on stress measurements and phase transformations in amorphous molybdenum/silicon and titanium/silicon multilayers is summarized. Stresses in as-deposited material depend on the period of the multilayer structure. The dependence of the stress on period can be explained by the existence of a thin intermixed layer between transition metal and silicon. The multilayers remain amorphous during annealing at low temperatures. Crystallization takes place after homogenization of the multilayer composite. The homogeneous amorphous silicide crystallizes in a metastable structure which transforms to the stable equilibrium structure during high-temperature annealing. The mechanical stress in crystallized layers is mainly due to the difference in thermal expansion between silicide and substrate.