Growth characteristics in initial stages of an aligned-orientation growth of epitaxial C49-structure TiSi2 grains selectively deposited by plasma-enhanced chemical vapor deposition (PECVD) are studied and compared with polycrystal growth of silicides in low-pressure chemical vapor deposition (LPCVD). PECVD was performed using TiCl4/Ar/H-2 gases with and without SiH4 at about 700 degrees C on (001)-oriented Si substrates. Ti atoms diffused into the silicon from the surface in the initial growth stages. The density of Ti atoms increased and epitaxial silicide grains were first formed when the density reached that of the disilicide. In LPCVD using TiCl4 and SiH4, island grains of a Ti-rich silicide (Ti5Si4) and a disilicide with multiple orientations were formed in the initial stages. The Ti-rich silicide was deposited due to the high rate of Cl reduction from TiCl4 by Si of the substrate and low SiH4 decomposition rate. In the succeeding deposition, the SiH4 decomposition rate increased and the Ti-rich silicide was changed into the C54-structure TiSi2. The difficulty of epitaxial growth in LPCVD results from the growth of multiple silicides, island growth, and stoichiometry change. Above difference in growth features between PECVD and LPCVD is caused by a difference in behaviors of Ti diffusion into silicon. The Ti-atom diffusion plays an important role in the aligned-orientation growth in PECVD.