Stencil Mask-Enabled Fabrication for Superconducting Qubits (Part 1)

Surface cleaning processes can improve superconducting qubit coherence times, suggesting that resist residues may contribute to qubit decoherence. One approach to tackle this is to eliminate resist-based fabrication and adopt a resist-free approach to assess the impact of organic residues. A prefabricated inorganic membrane with patterned openings, so-called stencil mask, enables the deposition of metal nanostructures without the need for the resist-liftoff process during junction fabrication. In the first part of this two-part talk, we explain the fabrication process of stencil masks based on low-stress silicon nitride membranes on silicon wafers. Furthermore, we compare the surface morphology and crystallinity of stencil-deposited nanostructures with those made via conventional resist-liftoff methods.