Properties of titanium nitride films prepared by direct current magnetron sputtering

Titanium nitride (TiN) thin films of different thickness were deposited by direct current (dc) magnetron sputtering under conditions of various N2 concentrations (0.5–34%). The electrical, optical, structural, compositional and morphological properties of the films were studied and the results were discussed with respect to N2 concentration and thickness of the films. At low N2 concentration of 0.5% (of the total sputtering pressure 1.1 Pa), golden coloured stoichiometric TiN films were obtained and with increase in the N2 concentration non-stoichiometric TiNx phases resulted. However, irrespective of the N2 concentration, the TiN stoichiometry in the films increased with increase in the film thickness. In the surface of the films the presence of nitride (TiN), oxynitride (TiOxNy) and oxide (TiO2) phases were observed and the quantity of these phases varied with the N2 concentration and thickness. The films of lower thickness were found to be amorphous and the crystallinity was observed in the films with increase in the thickness. The crystalline films showed reflections corresponding to the (1 1 1), (2 0 0) and (2 2 0) orientation of the cubic TiN and also features associated with TiNx phases. The transmission spectra of the films revealed the typical characteristics of the TiN films i.e. a narrow transmission band, however, the width varied with thickness, in the wavelength range of 300–600 nm and exhibited low transmission in the infrared region. The TiN films deposited at low N2 concentration of 0.5% showed smooth and uniform morphology with densely packed crystallites. With increase in N2 concentration various characteristics such as needle type crystallization, bubble precipitates and after bubble burst morphologies were observed in the films. However, at higher N2 concentration conditions, uniformity developed in the films with increase in thickness.