Formation of diamond like carbon films by plasma source ion implantation from CH4, C2H2 and C6 H6

Diamond like carbon (DLC) films were prepared by a plasma source ion implantation on silicon wafer and 440 C stainless steel substrates. Methane (CH₄), acetylene (C₂H₂), toluene (C₆H₅CH₃,) and benzene (C₆ H₆) were used as working gases for the plasma and the structure and properties of the films were compared. Radio frequency power was used to produce a glow discharge plasma. High negative voltage pulses of -20 kV were applied to a substrate holder to accelerate ions in the plasma. The surface morphology was observed by a field emission scanning microscope (SEM) and a atomic force microscope (AFM). Structure information of the DLC films was obtained by Raman spectroscopy. The composition analysis of the DLC films and film/substrate interface was carried out using Auger electron spectroscopy (AES). Hydrogen content of the films was estimated by a elastic recoil dispersion analysis (ERDA). Hardness of the films was measured by a indentation method. The friction coefficients of the films were measured with the aid of a reciprocating sliding tester. The results showed that the structure of the films and the interface structure and the properties varied with chemical structure of working gases. The DLC film prepared from CH₄ plasma was thinner than others. The films prepared from C₂H ₂, C₆H₅CH₃ and C₆H₆ plasma were thicker and exhibited high hardness. The integrated intensity ratio of “D” peak and “G” peak, I_DI_G, of the Raman spectra, was changed depend on working gases. The DLC films prepared by PSII had good wear properties