Silicidation behaviors of Co/Ti and Co/Hf bilayers on doped polycrystalline Si substrate

Silicide layer structures and morphological change of silicide/Si interface for Co/Ti and Co/Hf bilayers sputter-deposited on P-doped polycrystalline Si substrate and subjected to rapid thermal annealing were investigated and compared with those on single Si substrate. The CoSi-CoSi2 phase transition temperature is lower and morphological degradation of the silicide layer occurs more severely for Co/refractory metal bilayer on P-doped polycrystalline Si substrate than on single Si substrate. Also, the final layer structure of the films after silicidation annealing was found to depend strongly upon the interlayer metals. In the Co/Ti/poly-Si system, Si atoms pile up at the surface of the silicide layer, while no Si pile-up is observed for the Co/Hf/poly-Si system.