Characterisation of silicon carbide and silicon nitride thin films and Si3N4/SiC multilayers

Abstract

Silicon carbide (SiC), silicon nitride (Si3N4−δ) monolayers as well as Si3N4/SiC multilayers have been deposited on silicon substrates and cemented carbide inserts by r.f. magnetron sputtering technique. The used target materials were high purity silicon carbide (99.5%) and silicon nitride (99.9% ex. MgO binder). The deposition parameters (like substrate temperature and gas composition) have been varied to optimise the properties of the coatings. The substrate temperature was varied from 20 °C up to 700 °C. The Ar/N2 gas composition for deposition of silicon nitride thin films was varied over a wide range. Both the SiC and Si3N4−δ monolayers and the SiC/Si3N4 multilayers have been characterised by Fourier transform infrared spectroscopy (FT-IR), Auger electron spectroscopy (AES) and X-ray diffraction (XRD). The mechanical properties such as Vickers hardness, residual stress and film adhesion have been investigated. SiC and Si3N4 monolayers with the best properties were chosen to design Si3N4/SiC multilayers. The number of monolayers in the multilayer system with a constant total layer thickness was varied in order to investigate the influence of the interface on film constitution and film properties.