Investigation of TiN superconducting coplanar waveguide resonators fabricated with varying sputtering parameters

Superconducting qubits are crucial for advancing quantum computation, yet their performance remains highly sensitive to materials and fabrication conditions. While aluminum and niobium have been extensively studied, titanium nitride (TiN) has been proposed as a promising alternative for high-quality qubit components. In this study, we investigate the effects of varying sputtering parameters, such as pressure (0.7 µbar to 4 µbar) and temperature (room temperature to 600°C), on the properties and quality of TiN thin-films. We report a stable critical temperature (Tc) between 4.5K and 4.9K, depending on the sputtering conditions. Furthermore, internal quality factors (Q_i) of coplanar waveguide resonators (CPWs) fabricated from TiN thin-films were measured in the few GHz regime down to T=100mK. Q_i values improved significantly, reaching up to 6.7 × 10⁵ for films sputtered at 400°C and 2.5 µbar, compared to 1.6 × 10⁵ for films sputtered at room temperature and 4 µbar, suggesting a strong correlation between fabrication conditions, resulting film crystallinity and RF performance. Additionally, we have investigated the temperature dependence of Q_i in the range T=0.08K-1.5K, which indicates a turnover from two-level-system losses towards dominating quasiparticle losses at around 600mK. The findings are complemented with supporting XPS, XRD and AFM measurements.