Oxidation Resistance of Ti-Si-N and Ti-Al-Si-N Films Deposited by Reactive Sputtering Using Alloy Targets

Ti-Si-N and Ti-Al-Si-N films, which possess high hardness due to the formation of a nanocomposite structure in the films, were deposited by reactive magnetron sputtering using alloy targets and then postannealed in air at temperatures ranging from 300 to 800 degrees C. The hardness of both the films decreased significantly as postannealing temperature increased. However, the hardness of Ti-Al-Si-N films postannealed up to 500 degrees C remained at more than 30 GPa, which was significantly higher than that of the Ti-Si-N films after the post annealings. Electron probe microanalyses and X-ray photoelectron spectroscopy revealed that Al2O3 phases were formed in the postannealed Ti-Al-Si-N films. Transmission electron microscopy with energy-dispersive X-ray analysis showed that the Al2O3 layer of the postannealed Ti-Al-Si-N films was formed 40 nm below the surface, whereas the depth of the TiO2-SiO2 layer of the postannealed Ti-Si-N films was 100 nm from the surface. These results indicate that Al2O3 phases existed at the surface of the Ti-Al-Si-N films and prevented the oxidation of the interior of the films during postannealing at high temperatures in air. (C) 2011 The Japan Society of Applied Physics