Superconducting TiN Films Sputtered Over a Large Range of Substrate DC Bias

Abstract

We have investigated properties of superconducting titanium nitride (TiN) films that were sputtered over a large range of RF-induced DC bias voltage applied to the substrate. Films grown with the largest bias voltages contained cubic TiN phases with a large fraction of the (200) crystalline growth orientation. These films also contained the smallest concentrations of oxygen impurities, resulting in stoichiometric TiN. Over the range of bias, variations of the stress from slightly tensile to highly compressive were measured and correlated to crystallinity of the (200) growth. The films exhibited highly uniform thickness and resistivity, and show the potential for yielding reproducible low-temperature devices. Finally, coplanar resonators fabricated with the films exhibited high kinetic inductance and quality factor, where the latter was obtained in part from temperature-dependent frequency shifts.