The preparation of a-SiOCF films from Si (OC2H5) 4, C4F8 and/or Ar using a plasma-enhanced chemical vapour deposition method is reported. The chemical bonding structures of the films are analysed by high-resolution x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The results show that the films contain F-Si-O-Si, Si-OH, Si-O-Si, C-CF and C-F configurations. However, as for the film deposited from the feeding gases with Ar, a C-C configuration is also included in addition to the above-mentioned configurations. This indicates that the existence of Ar in the plasma leads to the formation of a fluorocarbon structure with a high degree of cross-linking. No evidence reveals the presence of a Si-C bond in the film, so it is believed that the fluorocarbon is perhaps embedded into the matrix of SiOF.