Room Temperature Plasma-Enhanced Niobium-Niobium Wafer Bonding for 3D Integration of Superconducting Interconnects for Quantum Processing

Quantum computing relies on a blend of superposition and entanglement phenomena of qubit devices to solve problems. It promises unparalleled computational throughput that has been earmarked to surpass that of even supercomputers. While the concept of quantum computing and quantum information processing has been established, there have been challenges in the scalability of qubits and the heterogeneous integration of qubits with control, read-out electronics. With the increased number of qubit devices, there is a pressing need to incorporate the many interconnects to address the qubits. 2.5D/3D advanced wafer-level packaging provides a solution to address these needs. Currently, Nb or Nb-based metals is one of the preferred superconducting interconnects for quantum devices and circuitry routing. This paper discusses the demonstration of a room-temperature wafer-to-wafer Nb bonding process for potential 3D stacking or integration of qubit circuitries, mechanical properties and handling.