Structure and mechanical properties of PACVD fluorinated amorphous carbon films

Abstract

Fluorinated amorphous carbon films were deposited by plasma assisted chemical vapour deposition from C 2H 2 and CF 4 gases. Gas mixture and bias voltage were changed. We analysed film structure by Raman and infrared spectroscopies and film hardness by micro-indentation. Raman spectra show a transition from diamond-like carbon films to polymer-like films as the CF 4 content in the plasma increases. The presence of a strong fluorescence background in the spectra of fluorine rich films indicates a polymer-like structure. Infrared spectra confirm the presence of CF x , F 2CCF 2 and F 2CC(HF) groups in the films. Hardness values are correlated with the trends of the D to G peak intensity ratio, I D/ I G. Mechanisms involved in film growth and formation are discussed especially regarding fluorine substitution for hydrogen.