Qubit-compatible substrates with superconducting through-silicon vias

TL;DR

This paper demonstrates superconducting through-silicon vias with high quality factors suitable for quantum processors, enabling larger and more complex 3D integrated quantum devices.

Contribution

It introduces superconducting vias with high internal quality factors, advancing 3D integration in quantum processor fabrication.

Findings

Internal quality factors of a million for test resonators

Vias perform on par with state-of-the-art silicon planar solutions

Enables larger, more complex quantum devices with 3D integration

Abstract

We fabricate and characterize superconducting through-silicon vias and electrodes suitable for superconducting quantum processors. We measure internal quality factors of a million for test resonators excited at single-photon levels, on chips with superconducting vias used to stitch ground planes on the front and back sides of the chips. This resonator performance is on par with the state of the art for silicon-based planar solutions, despite the presence of vias. Via stitching of ground planes is an important enabling technology for increasing the physical size of quantum processor chips, and is a first step toward more complex quantum devices with three-dimensional integration.