Characterizing the impacts of sequential Josephson Junction fabrication on superconducting circuit performance

As superconducting quantum circuit designs evolve in complexity, multiple steps of electron-beam lithography may be considered to facilitate the fabrication of gate electrodes, heterogeneous integration of different materials, or multiple types of Josephson junctions with different critical current densities. However, defects and residues introduced during the fabrication and processing of these devices can degrade their performance, and the tradeoffs associated with this additional processing must be evaluated and considered. In this work, we characterize a superconducting qubit fabrication flow that comprises two sequential Josephson junction (JJ) depositions. We explore the impact of this additional fabrication processing on superconducting circuits, and discuss the tradeoffs and considerations related to this additional processing.