Fabrication of Al-based superconducting high-aspect ratio TSVs for quantum 3D integration
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Abstract
We describe a microfabrication process that, thanks to a specifically tailored sidewall profile, enables for the first-time wafer-scale arrays of high-aspect ratio through-silicon vias (TSVs) coated with DC-sputtered Aluminum, achieving at once superconducting and CMOS-compatible 3D interconnects. Void-free conformal coating of up to 500μm-deep and 50μm-wide vias with a mere 2μm-thick layer of Al, a widely available metal in for IC manufacturing, was demonstrated. Single-via electric resistance as low as 468 mΩ at room temperature and superconductivity at 1.25 K were measured by a cross-bridge Kelvin resistor structure. This work establishes the fabrication of functional superconducting interposers suitable for 3D integration of high-density silicon-based quantum computing architectures.