The surface reaction ofCF2radicals on Si and fluorocarbon films was investigated in electron cyclotron resonance (ECR) Ar andH2/Ardownstream plasmas employingCF2radical injection technique. The effects ofAr+ions,Ar*metastable species and radiation from plasmas on the fluorocarbon film formation were evaluated in ECR Ar downstream plasma withCF2radical injection. As a result,CF2radicals with assistance ofAr+ion bombardment were found to play an important role in the fluorocarbon film formation. The adsorptive reactions ofCF2radicals on the fluorocarbon film surface with and without Ar andH2/Arplasma exposures were successfully investigated byin situFourier transform infrared reflection absorption spectroscopy andin situx-ray photoelectron spectroscopy. It was found that the formation of fluorocarbon film in the plasma proceeded through the adsorptive reaction ofCF2radicals at a high probability on the active sites formed by the bombardment ofAr+ions on the fluorocarbon film surface.