Exploring Low-Tc Tungsten and Hafnium Thin Films for Quantum Technologies

Low-critical-temperature (Tc) superconducting thin films, such as tungsten (W) and hafnium (Hf), are key materials for next-generation quantum and sensing technologies due to their favorable superconducting properties and compatibility with standard semiconductor fabrication. Achieving the desired low-Tc phase, however, requires precise control over deposition conditions and microstructural evolution. In this work, we investigate the thin film growth and phase formation of W and Hf thin films deposited by magnetron sputtering using a multi-chamber cluster tool at Lawrence Berkeley National Laboratory’s Molecular Foundry. Structural, compositional, and electrical characterizations are performed to elucidate the relationship between deposition temperature, crystalline phase, and superconducting behavior. By systematically varying substrate type, growth temperature, and film thickness, we examine how these parameters influence film crystallinity and the resulting superconducting transition. This comprehensive approach provides insight into the tunability of superconducting phases in refractory metals and establishes design guidelines for optimizing material properties for low-Tc kinetic inductance detectors and qubits for dark matter sensing and other quantum applications.