摘要(英) |
This thesis describes the continued development of photolithography processes for Josephson junction on two-inch and four-inch wafers. Using laser direct writing system from the instrument center of NCHU to produce the photomask with a line width of one micron was designed using the cross-type deposition principle. We use an e-gun system in NCU to deposit and oxidize aluminum metal film to create a
Josephson junction. The final goal of this fabrication process is to make parametric amplifiers on wafer scale. This thesis mainly discusses the impact of lift-off parameters on the success rate of the fabrication, and the impact of oxidation pressure on the room temperature resistivity of the Josephson junction when the pressure range of static oxidation is between 0.5 Torr and 4 Torr. In the lift-off test, we observe that the tilt angle of the sample during metal deposition, the thickness of the metal
film, and the uniformity of the exposed photoresist during exposure have the most significant impact on the lift-off yield. After fabricating the Josephson junction, and
excluding the wire resistance caused by the design, we find that the conductance of the Josephson junction is roportional to the area, and the conductance per unit
area is negatively related to the oxidation pressure. Finally, the Josephson junction and DC-SQUID produced by this process can properly adjust their resonant frequency. |
參考文獻 |
1] Tsuyoshi Yamamoto, K Inomata, M Watanabe, K Matsuba, T Miyazaki,
William D Oliver, Yasunobu Nakamura, and JS Tsai. Flux-driven josephson
parametric amplifier. Applied Physics Letters, 93(4):042510, 2008.
[2] Jing-Yang Zhang. Developing flux-driven josephson parametric amplifer. Master’s thesis, National Central University, 2022.
[3] Amr Osman. Reliability and reproducibility of josephson junction fabricationsteps towards an optimized process. Master’s thesis, Department of Microtechnology and Nanoscience Chalmers University of Technology, 2019.
[4] Wei-Cheng Jhang. Fabrication of superconducting quantum interference device.
Master’s thesis, National Central University, 2021.
[5] Ke Zhang, Meng-Meng Li, Qiang Liu, Hai-Feng Yu, and Yang Yu. Bridgefree fabrication process for al/alox/al josephson junctions. Chinese Physics B,
26(7):078501, 2017.
[6] Chao-Kai Mei. Optimization of josephson junction fabrication for parametric
amplifier. Master’s thesis, National Central University, 2023.
[7] GJ Dolan. Offset masks for lift-off photoprocessing. Applied Physics Letters,
31(5):337–339, 1977.
[8] GJ Dolan and John H Dunsmuir. Very small ( 20 nm) lithographic wires, dots,
rings, and tunnel junctions. Physica B: condensed matter, 152(1-2):7–13, 1988.
[9] Florent Lecocq, Ioan M Pop, Zhihui Peng, Iulian Matei, Thierry Crozes, Thierry
Fournier, C´ecile Naud, Wiebke Guichard, and Olivier Buisson. Junction fabrication by shadow evaporation without a suspended bridge. Nanotechnology,
22(31):315302, 2011.
[10] Martin G¨oppl, A Fragner, M Baur, R Bianchetti, Stefan Filipp, Johannes M
Fink, Peter J Leek, G Puebla, L Steffen, and Andreas Wallraff. Coplanar
waveguide resonators for circuit quantum electrodynamics. Journal of Applied
Physics, 104(11):113904, 2008.
[11] A Baust. Characterization of flux-driven josephson parametric amplifiers. Master’s thesis, Technische Universit¨at M¨unchen, 2010.
[12] Lujun Wang. Fabrication stability of josephson junctions for superconducting
qubits. Master’s thesis, Technische Universit¨at M¨unchen, 2015. |