Fast deposition of diamond-like hydrogenated carbon films

Diamond-like hydrogenated carbon films have been formed at low temperatures using methane and acetylene as precursor gases. The source used was of a cascaded arc type employing Ar and Ar/H₂ as carrier gases. Energies of ion species and ion densities in the plasma were measured with a mass energy probe and a Langmuir probe. The films produced were characterized in terms of sp³ content, refractive index, relative hydrogen content, hardness and adhesion. The variation of these parameters is presented as functions of precursor gas flow, process pressure, and surface temperature. Deposition rates up to 30 nm/s have been achieved using acetylene as precursor gas at substrate temperatures below 100 °C. Experiments with acetylene showed deposition rates seven times greater than with methane. The typical sp³ content of 55-78% in the films was determined by X-ray-Excited Auger Electron Spectroscopy (XAES) technique. The hardness and reduced modulus were determined by nanoindentation. Preliminary Atomic Force Microscopy (AFM) studies of the films showed a roughness below 3 nm (R_a).