Abstract: The radicals of CHF₃,C₆H₆ and CHF₃/C₆H₆ plasmas were measured by a quadruple mass spectrometer and an optical emission spectrometer in an electron cyclotron resonance plasma chemical vapor deposition system. The effects of microwave power and gas flow rate on the concentrations of these radicals were also analyzed. The results show that the increasing of microwave power leads to increase the concentration of C₂H₄, CF₂, HF and H₂ radicals, and to increase the deposition rate of fluorinated amorphous carbon films, and C/F in the films is controlled by F radicals.