Superconducting Funnelled Through-Silicon Vias for Quantum Applications

System downscaling, 3D integration, and increasing functionalities are the main challenges that integrated circuits and MEMS technology have dealt with in the past decade. Advanced packaging schemes and interconnect technologies are some of the successful approaches to tackle the challenges. These issues also extend to modern designs such as terahertz applications and quantum technologies, particularly the solid-state quantum computer.
In-demand instances of the latter are e.g. high-density quantum computing systems, where the layer implementing quantum bits (qubits) needs to be bridged to the microelectronic control layer. The latter typically requires CMOS-based circuitry compatible with cryogenic temperatures (i.e., cryo-CMOS) for the control and readout of the many physical qubits needed to implement error-tolerant logical qubits. In order to scale the number of qubits, a more efficient way for the interconnection of the qubits is necessary. In line with such a three-dimensional (3D) integration approach, an interposed layer featuring superconducting vertical interconnections such as through-silicon vias (TSVs) represents a crucial element in the fabrication and assembly of large, scalable, and densely integrated superconducting systems....