Methods for manufacturing semiconductor devices are disclosed. In one example, the semiconductor device has a gate and source/drain regions formed on a substrate. One example method includes introducing transition metal (Ti) source or precursor so that the introduced Ti source is chemisorbed onto the surface of the substrate and Ti mono-layer is formed; introducing semiconductor (Si) source so that the introduced Si source is chemisorbed onto the Ti mono-layer and Si mono-layer is formed; repeating the forming of the Ti and Si mono-layers; annealing the substrate to form a silicide layer (TiSi.sub.2) of C-54 phase; and patterning the C-54 phase TiSi.sub.2 layer to remain on the upper surfaces of the gate and source/drain regions.