Mechanical properties of Ta-Al-N thin films deposited by cylindrical DC magnetron sputtering: Influence of N2% in the gas mixture

Ta-Al-N thin films were deposited by cylindrical DC magnetron sputtering on a stainless steel substrate under varying nitrogen flow ratios (N-2 with respect to N-2 + Ar) in the range of 1.5%-9%. The effect of the N-2 content in the reactive gas mixture on crystalline structure, surface morphology, and mechanical properties of Ta-Al-N thin films was investigated. The amount of Al and Ta in deposited films was obtained by energy dispersive X-ray spectroscopy (EDX) analysis and films thickness was measured by surface step profilometer. X-ray diffraction analysis (XRD) revealed that the crystalline structure of the Ta-Al-N polycrystalline thin film is a mixture of TaAl, TaN, and AlN crystalline phases. Surface morphology, roughness, and grain size were investigated by atomic force microscopy (AFM). The nano hardness of Ta-Al-N thin films, measured by the nanoindentation method, was about 9GPa maximum for samples prepared under 3% N-2, and the friction coefficient, obtained by nanoscratch analysis, was approximately 0.2 for all Ta-Al-N thin films. Other results were found to be affected considerably by increasing the N-2 amount.