Effect of N2/Ar on structure and hardness of TaN-Ag thin films deposited by DC cylindrical magnetron sputtering

Abstract

TaN-Ag thin films were deposited on a 304 stainless steel substrate by cylindrical DC magnetron sputtering using different ratios of nitrogen to argon gas. The N2 percentages were 1.5%, 3%, 4.5%, 7.5%, 10.5% and 15% by volume. The influence of the N2/Ar ratio on the films morphology, structure and hardness was investigated using Atomic Force Microscopy (AFM), Grazing Incidence X-ray Diffraction (GIXRD), and the nanoindentation method. The amounts of Ta and Ag were determined using Energy Dispersive X-ray Spectroscopy (EDS). The thickness of the deposited films was measured by surface step profilometer. The RMS surface roughness increased for N2 percentages up to 7.5% and then decreased. Grazing results showed different TaN phases and Ag crystalline structures. The hardness of all films was much higher than the hardness of bulk silver or tantalum. The highest hardness value was obtained for 1.5% N2 . The EDS results indicated that the Ag/Ta ratio in the deposited films increases with increasing the N2 amount from 1.5% to 15%. The size of Ag islands on the surface was maximized at 7.5% N2 in the gas mixture. The thicknesses of films were in the range of 400-600 nm.