Effect of air annealing on mechanical properties and structure of SiCxNy magnetron sputtered films

Amorphous SiCxNy, films (of 2.2-2.7 mu m) were deposited on Si(111) substrates by reactive DC magnetron sputtering. The SIC target with small excess of carbon was sputtered at various N-2/Ar gas flow ratios (0-0.48). The as-deposited films were additionally annealed at temperatures of 700, 900 and 1100 degrees C in the air during 30 min and at 900 degrees C in vacuum during 1 h. The depth profile of hardness and elastic modulus (nanoindentation), change of the film thickness, film composition and structure (Raman and Infrared spectroscopy) were investigated in dependence on annealing temperature and content of nitrogen. The hardness of the as-deposited films decreases with the growth of N-2/Ar flow ratio. Air annealing at 700 degrees C leads to atomic short-range ordering in the amorphous Sic,N, films that significantly increases their hardness and elastic modulus at all used loads (10-100 mN). The hardness of the Sic(x)N(y) films annealed in air at 900 degrees C reduces when measured at low indenter loads (10-20 mN) due to onset of top layer oxidation. Hardness of inner layers, measured at 50-100 mN loads, increases approaching values exhibited by the vacuum annealed films. Air annealing at 1100 degrees C leads to intensive surface oxidation and formation of graphite-like structure in carbon clusters of inner layers. The hardness and oxidation resistance of the investigated SiCxNy films reduce with the increase of N-2/Ar ratio. (c) 2013 Elsevier B.V. All rights reserved.