Materials for Quantum Technology (Jan 2024)

Low-loss α-tantalum coplanar waveguide resonators on silicon wafers: fabrication, characterization and surface modification

  • D P Lozano,
  • M Mongillo,
  • X Piao,
  • S Couet,
  • D Wan,
  • Y Canvel,
  • A M Vadiraj,
  • Ts Ivanov,
  • J Verjauw,
  • R Acharya,
  • J Van Damme,
  • F A Mohiyaddin,
  • J Jussot,
  • P P Gowda,
  • A Pacco,
  • B Raes,
  • J Van de Vondel,
  • I P Radu,
  • B Govoreanu,
  • J Swerts,
  • A Potočnik,
  • K De Greve

DOI
https://doi.org/10.1088/2633-4356/ad4b8c
Journal volume & issue
Vol. 4, no. 2
p. 025801

Abstract

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The performance of state-of-the-art superconducting quantum devices is currently limited by microwave dielectric loss at different 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. Here, we demonstrate the fabrication of high-quality factor α -tantalum coplanar-waveguide resonators directly on pristine 300 mm silicon wafers over a variety of metal deposition conditions and perform a comprehensive material and electrical characterization study. Additionally, we apply a surface treatment based on hydrofluoric acid that allows us to modify different resonators surfaces, leading to a reduction in two-level system loss in the devices by a factor of three. This loss reduction can be entirely attributed to the removal of surface oxides. Our study indicates that large scale manufacturing of low-loss superconducting circuits should indeed be feasible and suggests a viable avenue to materials-driven advancements in superconducting circuit performance.

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