Fabrication and characterization of high-quality NbTiN thin films

NbTiN thin films have gained widespread application in superconducting electronics and quantum hybrid circuits owing to their superior superconducting characteristics, such as low resistivity (ρ_n), high critical temperature (T_c), high critical current density (J_c), and high critical magnetic field (B_c2). Nevertheless, the target poisoning effect arising from conventional co-sputtering methods poses significant challenges to the stable fabrication of high-quality NbTiN films, while also restricting the deposition rate. To mitigate target poisoning during deposition and enhance both the deposition rate and film quality, this study introduced a modification in the delivery of sputtering and reactive gases. Specifically, argon gas was directed toward the niobium and titanium targets, while nitrogen gas was exclusively supplied to the substrates. By employing this modified NbTiN deposition technique, plasma stability was improved at relatively low pressures, enabling the preparation of high -quality NbTiN films on various substrates.