Structure and Properties of Fluorinated Diamond-like Carbon Films Synthesized by Cathodic Vacuum Arc Source Technology

Fluorinated diamond-like carbon (a-C: F) films with different fluorine content were grown on silicon (100) substrate by pulse filtered cathodic vacuum arc source technology (FCVA). Influences of the fluorine incorporation on the various properties of the amorphous carbon based film were especially emphasized, including its microstructure, its mechanical properties and the hydrophobicity. The film composition and structure were successively characterized by X-ray photoelectron spectroscope (XPS) and laser Raman scattering spectroscope. Surface morphology and roughness were analyzed by atomic force microscope (AFM). Hardness and scratch resistance were measured by nano-indentation and nano-scratch, respectively. Water contact angles were measured by the sessile drop method. As a result, with the increase of CF4 flow rate in the feed gas, fluorine content was gradually increased to the film, the maximum fluorine content, 45.6 at% in the film was obtained. Raman spectra indicate that these films possess a diamond-like structure. The addition of fluorine to the amorphous carbon based film has a critical influence on its properties. The film surface becomes smoother due to the etching behavior of -CFn+. Hardness and the scratch resistance results show that these films have fairly good mechanical properties, the nano-hardness is all above 12GPa. The hydrophobicity of this film is evidently improved, with the contact angle of 106° of double-stilled water, approaching that of polytetrafluoroethylene (110°).