We studied the effect of gas addition on the surface morphology of titanium silicide films grown by plasma-enhanced chemical vapor deposition using a low-density plasma of TiCl4/SiH4/H-2/Ar gases. We examined the use of ClF3, SiF4, F-2, and SiCl4 as additional gases and found the F-containing gases to be effective for forming continuous films. Deposition with SiCl4 and without additional gases results in films with slits among the silicide grains, showing that the effect on the surface morphology is due to fluorine. The surface morphology of the film indicated that the fluorine suppresses atom movement. Although ClF3 gas addition caused etch pits in the substrate, it also resulted in a continuous epitaxial film with a C49-structure TiSi2 being selectively deposited on a (001)-oriented Si surface with a SiO2 mask.