Novel amorphous SiCN coatings are becoming increasingly attractive because of their mechanical, optical and electronic properties. In the present work, SiCN films were fabricated by PECVD from SiH4/CH4/N-2/Ar gas mixtures at a temperature of 400 degreesC. Mechanical properties such as hardness, Young's modulus, friction coefficient and stress were evaluated, respectively, by depth-sensing indentation, pin-on-disk, micro-scratch and curvature methods. Films deposited under optimized conditions exhibited a hardness > 30 GPa, Young's modulus > 190 GPa, elastic rebound of 85% and a compressive stress of approximately I GPa. A friction coefficient against Al2O3, ranging from 0.75 to 0.25 and a low surface roughness of approximately 1 nm were found to be accompanied by a refractive index ranging from 1.85 to 2.10 (at 550 nm) and an extinction coefficient between 1.0 X 10(-4) and 4.5 X 10(-2). The film behavior is correlated with the microstructure and composition determined by SEM, XPS, AFM and broad-range UV-VIS-NIR-IR spectroscopic ellipsometry. (C) 2003 Elsevier B.V. All rights reserved.