Manufacturing high-Q superconducting α-tantalum resonators on silicon wafers

Abstract

The performance of state-of-the-art superconducting quantum devices is currently limited by microwave dielectric losses at different surfaces and interfaces. α-tantalum is a superconductor that has proven effective in reducing dielectric loss and improving device performance due to its thin low-loss oxide. However, without the use of a seed layer, this tantalum phase has so far only been realised on sapphire substrates, which is incompatible with advanced processing in industry-scale fabrication facilities. Here, we demonstrate the fabrication of high-quality factor α-tantalum resonators directly on silicon wafers over a variety of metal deposition conditions and perform a comprehensive material and electrical characterization study. By comparing experiments with simulated resonator loss, we demonstrate that two-level-system loss is dominated by surface oxide contributions and not the substrate-metal interface. Our study paves the way to large scale manufacturing of low-loss superconducting circuits and to materials-driven advancements in superconducting circuit performance.

20 pages, 10 figures

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Cited by in corpus (4)

• Low-Loss Superconducting Resonators Fabricated from Tantalum Films Grown at Room Temperature
• Reversing Hydrogen-Related Loss in $\alpha$-Ta Thin Films for Quantum Device Fabrication
• Investigation of tantalum films growth for coplanar resonators with internal quality factors above ten million
• In situ Al${}_2$O${}_3$ passivation of epitaxial tantalum and aluminum films enables long-term stability in superconducting microwave resonators