SiOF like films have been elaborated in microwave excited DECR plasma reactor (Distributed Electron Cyclotron Resonance) from a mixture of oxygen-hexamethyldisiloxane (HMDSO/O2) and CF4. The fluorine contents in the precursor mixture were adjusted by varying the CF4 gas flow ratio in the range of 10% - 70%. Optical emission spectroscopy (OES) and Fourier transform infrared (FTIR) have been used for the plasma diagnostic and the deposited films structure analysis, respectively. Actinometric technique was used to find trends in the concentrations of species present in the plasma. A large number of species have been detected, such as F, Si, O, C and H. Depending on the gas mixture composition, FTIR spectra revealed the presence of several chemical bonds such as Si-F and Si-O.