Fabrication of superconducting through-silicon vias

Understand

Increasing circuit complexity within quantum systems based on superconducting qubits necessitates high connectivity while retaining qubit coherence.

• Classical micro-electronic systems have addressed interconnect density challenges by using 3D integration with interposers containing through-silicon vias (TSVs), but extending these integration techniques to superconducting quantum systems is challenging.
• Here, we discuss our approach for realizing high-aspect-ratio superconducting TSVs\textemdash 10 $\mu$m wide by 20 $\mu$m long by 200 $\mu$m deep\textemdash with densities of 100 electrically isolated TSVs per square millimeter.
• We characterize the DC and microwave performance of superconducting TSVs at cryogenic temperatures and demonstrate superconducting critical currents greater than 20 mA.