Highly-conformal sputtered through-silicon vias with sharp superconducting transition
J.A. Alfaro Barrantes (TU Delft - EKL Processing)
M. Mastrangeli (TU Delft - Electronic Components, Technology and Materials)
David Thoen (TU Delft - Tera-Hertz Sensing)
Sten Visser (SRON–Netherlands Institute for Space Research)
J. Bueno Lopez (TU Delft - Tera-Hertz Sensing, TU Delft - Electronics)
J.J.A. Baselmans (TU Delft - Tera-Hertz Sensing)
P.M. Sarro (TU Delft - Electronic Components, Technology and Materials)
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Abstract
This paper describes the microfabrication and electrical characterization of aluminum-coated superconducting through-silicon vias (TSVs) with sharp superconducting transition above 1 K. The sharp superconducting transition was achieved by means of fully conformal and void-free DC-sputtering of the TSVs with Al, and is here demonstrated in up to 500μ m-deep vias. Full conformality of Al sputtering was made possible by shaping the vias with a tailored hourglass profile, which allowed a metallic layer as thick as 430 nm to be deposited in the center of the vias. Single-via electric resistance as low as 160 mΩ at room temperature and superconductivity at 1.27 K were measured by a three-dimensional (3D) cross-bridge Kelvin resistor structure. This work establishes a CMOS-compatible fabrication process suitable for arrays of superconducting TSVs and 3D integration of superconducting silicon-based devices. [2020-0354].