Temperature Dependent Reaction of Thin Ni-Silicide Transrotational Layers on 001Si

摘要

The phase transition from pure Ni to Ni2Si and NiSi was studied by in situ Transmission Electron Microscopy analyses from room temperature to 260掳C. The reaction starts at 180掳C with the formation of small Ni2Si transrotational domains. Their density and size increase by increasing the annealing temperature to 260掳C. After 50 min, a uniform transrotational NiSi layer is formed by a grain by grain transition process. A polycrystalline NiSi layer was instead obtained at 550掳C. It was concluded that the final layer structure is the result of a competition: at low temperature (260掳C) transrotational domains prevails since slow structural modifications allow the match between silicide and silicon during the Ni2Si -NiSi phase transition; at high temperature (550掳), the growth of randomly oriented silicide grains is favoured.