The effect of annealing on the structural, optical and electrical properties of Titanium Nitride (TiN) thin films prepared by DC magnetron sputtering with supported discharge

Abstract

Nano-crystalline Titanium Nitride (TiN) thin films were deposited on glass substrates by reactive DC magnetron sputtering in the presence of a supported discharge (dc triode magnetron sputtering). A hot thermionic filament which was negatively biased is kept between the target and substrate, and was used to sustain the discharge at much lower pressures. The TiN films deposited at room temperature (RT) were annealed at different temperatures of 373, 473 and 573 K in a high vacuum for 1 h. The films were characterized for their morphological, structural, micro-structural, optical and electrical properties. RT deposited titanium to nitrogen ratio was found to be 1:1 which has been confirmed by EDAX. XRD studies showed that the as-deposited TiN thin film were amorphous in nature and transformed to a nano-crystalline structure with increasing annealing temperatures. The crystallite growth of TiN thin films started around 373 K onwards, and it became a face-centered cubic structure with a preferred orientation along the (111) plane. The band gap of TiN thin films was found to increase from 2.7 to 3.2 eV with an increase in the annealing temperature. The photoluminescence spectrum of TiN thin films indicates a broadening of emission wavelength in the visible region with a maximum emission peak around 360 nm. The electrical resistivity of TiN thin films was found to drop significantly from 1800 to 400 µΩ cm with an increase in the annealing temperature. The AFM micrographs of annealed TiN thin films show uniform surface pattern associated with a large accumulation of fine grains. Through this work, it has been demonstrated that it is possible to achieve the required physical properties of TiN films at lower annealing temperatures by the supported discharge dc magnetron technique compared to other sputtering techniques.