A study of superconducting behavior in ruthenium thin films

Ruthenium (Ru) is a promising candidate for next-generation electronic interconnects due to its low resistivity, small mean free path, and superior electromigration reliability at nanometer scales. In addition, Ru exhibits superconductivity below 1 K, with resistance to oxidation, low diffusivity, and a small superconducting gap, making it a potential material for superconducting qubits and Josephson Junctions. Here, we investigate the superconducting behavior of Ru thin films (11.9–108.5 nm thick), observing transition temperatures from 657.9 to 557 mK. A weak thickness dependence appears in the thinnest films, followed by a conventional inverse thickness dependence in thicker films. Magnetotransport studies reveal type-II superconductivity in the dirty limit (ξ ≫ l), with coherence lengths ranging from 13.5 to 27 nm. Finally, oxidation resistance studies confirm minimal RuOx growth after seven weeks of air exposure. These findings provide key insights for integrating Ru into superconducting electronic devices.