A method for forming a metal silicide. The method comprises: providing a substrate having a fin, a gate formed on the fin, and spacers formed on opposite sides of the gate; depositing a Ti metal layer; siliconizing the Ti metal layer; and removing unreacted Ti metal layer. As the Ti atoms have relatively stable characteristics, diffusion happens mostly to Si atoms while the Ti atoms rarely diffuse during the thermal annealing. As a result, current leakage can be prevented in a depletion region and thus leakage current of the substrate can be reduced.