SiC films were synthesized by hot-wire chemical vapor deposition using a tungsten filament and a gas mixture of SiF4 and CH4. The etching of the substrate instead of the film growth occurred on the samples prepared using only source gases without H-2 dilution. The atomic or molecular hydrogen was believed to control the density of radicals containing F in a gas phase or on a growth surface. Polycrystalline 3C-SiC(111) films were successfully obtained at substrate temperatures lower than 500 degrees C by using H-2 dilution. The growth mode limited by source-gas supply was found to be important to obtain polycrystalline SiC films. The SiC film grown at higher deposition pressure was amorphous and contained no Si-H-x bonds but 6% fluorine. In SiF4/CH4/H-2 system, the radicals containing F are considered to play very important roles in the reactions both on a growth surface and in a gas-phase. (C) 2007 Elsevier B.V. All rights reserved.