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arXiv · 2301.04065

Lower-temperature fabrication of airbridges by grayscale lithography to increase yield of nanowire transmons in circuit QED quantum processors

T. Stavenga·L. DiCarlo
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Abstract

Quantum hardware based on circuit quantum electrodynamics makes extensive use of airbridges to suppress unwanted modes of wave propagation in coplanar-waveguide transmission lines. Airbridges also provide an interconnect enabling transmission lines to cross. Traditional airbridge fabrication produces a curved profile by reflowing resist at elevated temperature prior to metallization. The elevated temperature can affect the coupling energy and even yield of pre-fabricated Josephson elements of superconducting qubits, tuneable couplers and resonators. We employ grayscale lithography in place of reflow to reduce the peak airbridge processing temperature from $200$ to $150^\circ\mathrm{C}$, showing a substantial yield increase of transmon qubits with Josephson elements realized using Al-contacted InAs nanowires.

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T. Stavenga, L. DiCarlo. 2023-01-10. Lower-temperature fabrication of airbridges by grayscale lithography to increase yield of nanowire transmons in circuit QED quantum processors. https://doi.org/10.1063/5.0146814

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