Oxidation resistance and mechanical property of cosputtered quasi-amorphous Ta–Si–N films under vacuum rapid thermal annealing

Abstract

The oxidation resistance and mechanical properties of Ta–Si–N films at high temperature are important issues for application. In this paper, quasi-amorphous Ta–Si–N thin films were fabricated by using reactive magnetron co-sputtering at different Si/Ta power ratios and nitrogen flow ratios (FN 2% = FN 2/(FAr + FN 2) × 100%). Vacuum rapid thermal annealing at 600–900 °C at 2.6 Pa was performed to investigate the oxidation resistance of films. At the higher Si/Ta power ratio and increased FN 2%, there is low oxygen fraction (O/(O + N) ≤ 0.2) of films at high annealing temperature which corresponds to benefit oxidation resistance. The crystalline δ-Ta 2O 5 phase was formed at 900 °C for all films. The islands of oxide were formed on the surface of films at low-Si-content (≤ 20 at.%) after 900 °C annealing. The hardness of all as-deposited Ta–Si–N films was between 16 and 24 GPa. The low-Si-content Ta–Si–N films has higher hardness than high-Si-content (≥ 20 at.%) ones due to lower fraction of soft amorphous SiN x. The effect of annealing temperature on the correlation among process parameters, microstructure, phase transformation and hardness is discussed. The Ta–Si–N formed at 6 FN 2% and Si/Ta power ratio of 2/1 can be the best candidate for good oxidation resistance with appropriate mechanical property.