A new Plasma-Enhanced Chemical Vapor Deposition (PECVD) method using (C2H5O)3SiF: tri-ethoxy-fluoro-silane as an interlayer dielectric film is proposed based on considerations of gas chemistry. RF power dependence of the film characteristics is investigated, and it is clarified that fluorine stability is improved with increasing RF power. The relative dielectric constant of the films deposited at the power of more than 700 W is about 3.5. Moisture absorption of the film formed from TEFS at 900 W is smaller than that of the SiOF film formed from C2F6 added TEOS.