C49 C54 PHASE-TRANSFORMATION DURING CHEMICAL-VAPOR-DEPOSITION OF TISI2/

The initial stages of chemical vapor deposition of TiSi2 from TiCl4, H -2, and Si(100) have been investigated with respect to the phase forma tion sequence. The result showed that the metastable C49 TiSi2 phase w as formed prior to the equilibrium C54 TiSi2 phase. As the growth cont inued, the C49 phase was transformed to the C54 phase. X-ray diffracti on analyses showed that both TiSi2 phases exhibited an epitaxial-like growth with respect to the substrate. Moreover, the transformation fro m the C49 phase to the C54 phase was favored by increased film thickne ss rather than high-temperature annealing. The results could be explai ned by an interfacial stabilization effect where the metastable C49 ph ase is stabilized by epitaxy. In addition, the influence of oxygen and carbon on the process was investigated by adding O-2 and C2H4 to the reaction gas mixture. Oxygen had no effect while a minor stabilization of the C49 phase was observed when carbon was introduced during depos ition.