Nitrogen concentration dependent mechanical properties of TiNx single-phase films (0.75≤x≤0.99)

Abstract

TiNx films with different nitrogen concentration were synthesized on the Si (100) substrates by enhanced magnetic filtering arc ion plating. The morphologies, compositions, microstructures, residual stress, carrier mobility, hardness and elastic modulus of as-deposited films were characterized by field emission scanning electron microscope, X-ray photoelectron spectrometry, X-ray diffraction, Hall effect measurements and Nanoindenter. The results showed that TiNx films perform the rock-salt single-phase structure as the nitrogen concentration x rises from 0.75 to 0.99. The preferred orientation, thickness, grain size and residual stress of TiNx films with different nitrogen concentration x all keep consistent. The carrier mobility obtained a minimum value near x=0.82. The hardness and elastic modulus of TiNx films first increase and then decrease, reaching the top of 32.2GPa and 433.6GPa at the stoichiometry point TiN0.82. The strengthening mechanism was discussed and the hardness enhancement may be attributed to the different electronic structure at different nitrogen concentration x.