Structural and electrical properties of fluorinated silicon dioxide (SiOF) films prepared by remote plasma enhanced chemical vapor deposition from the SiF4–O2–H2–He gas mixture have been studied using ellipsometry, Fourier transform infrared spectroscopy, transmission electron microscopy, and current–voltage measurements. It has been found that the level of hydrogen dilution strongly affects the microstructure of deposited SiOF films. The films prepared at the H2 flow rate below about 0.8 sccm have a biphase structure consisting of an amorphous matrix with the incorporation of 5–30 nm sized particles. The main origin of these particles seems to be gas phase oxidation of SiFx species (with x=1, 2, 3) in plasma and downstream regions. Resulting films are characterized by extremely low density, reduced structural homogeneity, and poor electrical properties. Increase in the H2 flow rate above 0.8 sccm completely suppresses the incorporation of particles into the growing film probably due to effective hindering gas phase oxidation process and results in dense homogeneous amorphous SiOF films with good electrical properties. © 2000 American Vacuum Society.