Synthesis and study of highly dense and smooth TiN thin films

Abstract

This study aims towards a systematic reciprocity of the tunable synthesis parameters -partial pressure of N 2 gas, ion energy (E i ) and Ti interface in TiN thin film samples deposited using ion beam sputtering at ambient temperature (300 K). At the optimum partial pressure of N 2 gas, samples were prepared with or without Ti interface at E i = 1.0 or 0.5 keV. They were characterized using x-ray reflectivity (XRR) to deduce thickness, roughness and density. The roughness of TiN thin films was found to be below 1 nm, when deposited at the lower E i of 0.5 keV and when interfaced with a layer of Ti. Under these conditions, the density of TiN sample reaches to 5.80(±0.03) g cm −3 , a value highest hitherto for any TiN sample. X-ray diffraction and electrical resistivity measurements were performed. It was found that the cumulative effect of the reduction in E i from 1.0 to 0.5 keV and the addition of Ti interface favors (111) oriented growth leading to dense and smooth TiN films and a substantial reduction in the electrical resistivity. The reduction in E i has been attributed to the surface kinetics mechanism (simulated using SRIM) where the available energy of the sputtered species (<E sp >) leaving the target at E i = 0.5 keV is the optimum value favoring the growth of defects free homogeneously distributed films. The electronic structure of samples was probed using N K-edge absorption spectroscopy and the information about the crystal field and spin-orbit splitting confirmed TiN phase formation. In essence, through this work, we demonstrate the role of <E sp > and Ti interface in achieving highly dense and smooth TiN thin films with low resistivity without the need of a high temperature or substrate biasing during the thin film deposition process.