Electrical transport and i n s i t u x-ray studies of the formation of TiSi2 thin films on Si

Abstract

The formation of TiSi₂ thin films on Si has been investigated by in situ x‐ray diffraction and electrical transport. The x‐ray results show unequivocally that the staging proceeds through two orthorhombic polytypes of TiSi₂ according to the sequence: sputter‐deposited metallic Ti or TiSi_x alloy films on Si(001)→TiSi₂ (C49 structure)→TiSi₂ (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 important, 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 12.4 μΩ cm at room temperature and 0.66 μΩ cm at 4.2 K.