The contamination of unwanted atoms such as oxygen that may originate from residual gas in reactant chambers is common in the deposition of SiC films. In this study, CF4 was introduced into a chamber while preparing SiC films by hot filament chemical vapor deposition using CH4, SiH4, and H-2, and then the films were characterized by Fourier transform infrared (FTIR) spectrometer and x-ray photoelectron spectrometry (XPS). The FTIR and XPS results showed that the CF4 addition could reduce the oxygen content in the films. It is concluded that the reduction of oxygen is due to the reaction of active F* (or CFn*), O*, Si* (or SiHn*), and C* (or CHn*) in the process. Simultaneously, the results indicate also that the addition of CF4 could improve the degree of ordering of the Si-C bonds and lead to a decrease in the growth rate. The influence of CF4 addition on the ordering of the Si-C bonds and the growth rate of the films is discussed. (C) 2003 American Vacuum Society.