Investigation of C49-C54 TiSi2 transformation kinetics

The C49,ÜíC54 TiSi2 polymorphic transformation has been investigated trying to elucidate the relative role played by nucleation and growth in silicide formation. Samples having an amorphous layer and C54 seeds have been made by heat treatment of a Ti/Si bi-layer structure and subsequent suitable Ar ion implantation. In situ resistance measurements performed during heat treatments in controlled and purified atmosphere at constant heating rates and ex situ X-ray diffraction, MeV 4He+ backscattering spectrometry and cross-section transmission electron microscopy have been used to characterize the samples. The results show that in a sample with C49 the C54 nucleation occurs at 800 ¬?C; when C54 seeds are present the growth is appreciable already at temperatures as low as 400-500 ¬?C. It has also been shown that nucleation and growth of the C49 phase is a process competitive to the growth of the C54 phase.