Superconducting interconnects for thermal management of 3D quantum systems

Scaling up semiconductor quantum systems requires dealing with thermal and architectural challenges, especially related to the power dissipation of co-integrated control electronic circuits. This motivates efforts to develop integrated high thermal resistance interconnects. To achieve this, using the intrinsic thermal properties of superconductors, we investigate their integration as superlattices to further enhance their thermal resistance via phonon interface scattering.

In this study, superlattices with 5-period TiN/Nb bilayers were fabricated to morphologically, electrically, and thermally evaluate the potential of this interconnect technology. The superlattice demonstrated an effective critical temperature of 8.4 K and an upper critical field of 5 T, showing a strong proximity coupling between the layers. Thermal conductivity measurements at sub-K temperatures revealed excellent thermal resistive properties, with a thermal conductivity of 9.7×10⁻⁷ W/m·K at 1 K, and consistent with phonon transport limitations due to thermal boundary resistance. These results highlight this technology’s potential as an effective, thermally resistive solution for interconnects within 3D integrated quantum systems. A two-tier demonstrator comprising these superconducting superlattice interconnects will be presented.