A new plasma-enhanced chemical vapor deposition (CVD) system with an in-situ monitoring system by laser Raman spectroscopy was developed by which it is possible to obtain Raman spectra even when the thickness of a TiO2 film is only about 27.5 Angstrom. A peak corresponding to titanium silicide was observed at the early growth stage of TiO2. It was made clear that titanium silicide decomposes with the process of growth and plays a role in the conversion of amorphous titanium dioxide to a crystalline one and enhances the growth of crystal.