Stoichiometry ratio-induced structural and electronic properties changes of TaN thin films prepared by reactive magnetron sputtering

Abstract

Tantalum nitride (TaN) is a representative compound with a variety of compositions and mesoscopic phases, which ultimately leads to a diversity of properties. In order to explore relationship between the stoichiometry and properties, in this work, TaN thin films were prepared by reactive sputtering and modulated by controlling the percentage of nitrogen (PN2). All the prepared films were dense and uniform, which exhibited a δ-TaN phase structure. The decrease of nitrogen vacancies directly caused the slightly shift of XRD diffraction peaks and the increase in grain size, both of which showed a lattice distortion of the films. It is also found that the presence of nitrogen vacancies affectes the distribution of the Ta cation as well as the nitrogen-tantalum stoichiometry ratios, so that the deficient material exhibits different electrical properties. The TCR of TaN in this work achieved as low as 32.9 ppm/°C (nitrogen-tantalum ratio of 0.843), which is attributed to the nitrogen vacancies in TaN lattice effectively regulating the electron scattering in the vicinity of Ta atoms. Meanwhile, the change in resistivity is only 1 %, indicating a good long-term stability of TaN. This study provides a point of reference for the preparation of film resistors from the perspective of material modulation.