Optical emission study of CH4+CHF3 ECR plasma and properties of a-C:F:H films

Abstract a-C:F:H films were prepared with a mixture of CH 4 and CHF 3 gases by microwave electron cyclotron resonance chemical vapor deposition method. An actinometer optical emission spectroscopy was used to reveal the trend in the concentration of some species (H, F, C 2 , CH etc.) as a function of flow ratio R {[CHF 3 ]/([CHF 3 ]+[CH 4 ])}. The results from Fourier transform infrared transmission spectroscopy showed the structural evolution of a-C:F:H films with variable gas flow ratios R . This structural evolution had an influence on the film optical band gap. The optical band gap decreased with the increasing flow ratios R in the polymer-like region, while it increased in the PTFE-like region. The correlation between the C 2 species density and the properties of a-C:F:H films is also discussed.