[C-6] Quantum Computing IV

[C-6-03] Uniformity Improvement of Josephson Junction Resistance by Considering Al Deposition on a Resist Sidewall for Large-scale Integration of Qubits

〇Tsuyoshi Takahashi^1,2, Norinao Kouma^1,2, Yoshiyasu Doi^1,2, Shintaro Sato^1,2, Shuhei Tamate², Yasunobu Nakamura^2,3 (1. Fujitsu Limited (Japan), 2. RIKEN (Japan), 3. Univ. of Tokyo (Japan))

Presentation style: On-site (in-person)

https://doi.org/10.7567/SSDM.2022.C-6-03

We report an improvement in the uniformity of Josephson junctions (JJs) in wafer-scale superconducting quantum bit (qubit) chips. We revealed that junction-resistance (RN) variations in Al/AlOx/Al JJs are due to unintentional Al deposition on the resist mask sidewall during shadow mask evaporation. We developed a new two-step shadow evaporation method and success-fully reduced variations in the RN of JJs in a 3-inch wafer from 6.7% to 4.5%, corresponding to 1.1% in a 16-qubit chip with dimensions of 10 mm × 10 mm. This method is promising for developing large-scale super-conducting quantum computers.