Effect of nitrogen gas flow on amorphous Si–C–N films produced by PVD techniques

Abstract

Si C N thin films were deposited by reactive magnetron sputtering on glass and steel substrates. The films were grown in a x y z rotation mode over a carbon and a silicon targets in a mixed Ar/N2 atmosphere at a substrate temperature of 300 °C. The 2 substrates were held grounded or at a negative bias of -25 and -50 V. The film characteristics were also controlled by nitrogen flow. Binary and ternary films were obtained. The films were analysed with respect to microstructure, state of chemical bonding and optical properties by Raman spectroscopy (RS) and optical transmittance. RS was used as a probe of micro-structural modifications induced by deposition conditions. The main features observed in RS spectra are the well-known D- and G-bands characteristic of amorphous carbon. The position, widths and intensity ratio of these bands are found to be dependent on the film composition. The refractive index, the absorption coefficient and also the thickness were calculated from transmittance spectra obtained between 200 and 2500 nm. The hardness and Young’s modulus of the films were measured by nano-indentation experiments. The average hardness and Young’s modulus of the produced coatings was 21 and 200 GPa, respectively.