Electrical transport and in-situ x-ray studies of the formation of TiSi sub 2 thin films on Si.

The formation of TiSi sub 2 thin films on Si has been investigated by in-situ x-ray diffraction and by electrical transport. The x-ray results show unequivocally that the staging proceeds through two orthorhombic polytypes of TiSi sub 2 according to the sequence: sputter deposited metallic Ti or TiSi sub x alloy films on Si (001) -> TiSi sub 2 (C49 structure) -> TiSi sub 2 (C54 structure), with no evidence of lower silicides. Electrical transport shows metallic behavior for all phases and distinctive features in the annealing curves which correlate with the structural transformations. Most importantly, the resistivity, characteristically very high for the C49 phase, undergoes a precipitous drop at the C49 -> C54 transition. In the C54 phase when fully annealed the resistivity is 12. 4micro Ohms cm at room temperature and 0.66 micro Ohms cm at 4.2K.