Reaction kinetics of molybdenum thin films on silicon (111) surface

Abstract

Silicon-metal systems are highly susceptible to solid-solid reactions which modify their electrical and mechanical properties. Although many works are dealing with silicide formation, the molybdenum-silicon system has not yet been investigated in detail to our knowledge. In this paper we present a He+ ion backscattering study of the molybdenum-silicide formation by interaction of a thin molybdenum layer and a silicon 〈111〉 wafer. The silicide phases Mo3Si and MoSi2 have been identified by x-ray diffraction and transmission electron microscopy. Surface transformations were observed by scanning electron microscopy. For an 800-Å Mo layer sputter deposited on silicon, we have found a time-square growth rate for MoSi2 with an average activation energy of 2.4 eV in the temperature range 475–550 °C. The fundamental roles of the cleaning of the silicon surface, of the substrate temperature during sputtering, and of the stresses in the layer are pointed out.