Structure dependent resistivity and dielectric characteristics of tantalum oxynitride thin films produced by magnetron sputtering

• Published in: Applied surface science 2015-11, Vol.354 (B), p.298-305
• Main Authors: Cristea, D., Crisan, A., Cretu, N., Borges, J., Lopes, C., Cunha, L., Ion, V., Dinescu, M., Barradas, N.P., Alves, E., Apreutesei, M., Munteanu, D.
• Format: Article
• Language: English
• Subjects: Concentration (composition); Deposition; Dielectric constant; Dielectrics; Electrical properties; Electrical resistivity; Engineering Sciences; High speed tool steels; Magnetron sputtering; Materials; Silicon substrates; Tantalum; Tantalum oxynitride; Thin films
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2015.06.167

•Tantalum oxynitride thin films have been deposited by magnetron sputtering, in various configurations.•The rising of the reactive gases mixture flow has the consequence of a gradual increase in the non-metallic content in the films, which results in a 10 orders of magnitude resistivity domain.•The higher resistivity films exhibit dielectric constants up to 41 and quality factors up to 70. The main purpose of this work is to present and to interpret the change of electrical properties of TaxNyOz thin films, produced by DC reactive magnetron sputtering. Some parameters were varied during deposition: the flow of the reactive gases mixture (N2 and O2, with a constant concentration ratio of 17:3); the substrate voltage bias (grounded, −50V or −100V) and the substrate (glass, (100) Si or high speed steel). The obtained films exhibit significant differences. The variation of the deposition parameters induces variations of the composition, microstructure and morphology. These differences cause variation of the electrical resistivity essentially correlated with the composition and structural changes. The gradual decrease of the Ta concentration in the films induces amorphization and causes a raise of the resistivity. The dielectric characteristics of some of the high resistance TaxNyOz films were obtained in the samples with a capacitor-like design (deposited onto high speed steel, with gold pads deposited on the dielectric TaxNyOz films). Some of these films exhibited dielectric constant values higher than those reported for other tantalum based dielectric films.