Systematic study of amorphous hydrogenated and fluorinated carbon films

Amorphous fluorinated carbon films were grown from CF(4) and C(2)H(2) mixtures, using a Plasma Assisted Chemical Vapour Deposition (PACVD) apparatus. Two sets of films were deposited, changing in a systematic way the CF(4) flux and the bias voltage (V(b)). Film composition and structure were analysed by secondary ion mass spectroscopy (SIMS), infrared (IR) and Raman spectroscopies. Film hardness was obtained by micro-indentation measurements. On increasing fluorine content in films, hardness decreases and a fluorescence background in Raman spectra appears at high fluorine content, showing a diamond- to polymer-like structural transition. Infrared spectra indicate the presence of -CF(x), C=CHF and C=CF(2) groups in the films. Our data are compared with previous results in the literature and the mechanisms involved in film formation are discussed, especially regarding fluorine substitution for hydrogen.