Progress in Superconductivity

The Korean Superconductivity Society (한국초전도학회)
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Employing Al Etch Stop Layer for Nb-based SNS Josephson Junction Fabrication Process

Al 식각정지층을 이용한 Nb-based SNS 조셉슨 접합의 제조공정

  • Choi, J.S. (Korea Research Institute of Standards and Science) ;
  • Park, J.H. (Korea Research Institute of Standards and Science) ;
  • Song, W. (Korea Research Institute of Standards and Science) ;
  • Chong, Y. (Korea Research Institute of Standards and Science)
  • Received : 2011.03.11
  • Accepted : 2011.04.07
  • Published : 2011.04.30
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Abstract

We report our efforts on the development of Nb-based non-hysteretic Josephson junction fabrication process for quantu device applications. By adopting and modifying the existing Nb-aluminum oxide tunnel junction process, we develop a process for non-hysteretic Josephson junction circuits using metal-silicide as metallic barrier material. We use sputter deposition of Nb and $MoSi_2$, PECVD deposition of silicon oxide as insulator material, and ICP-RIE for metal and oxide etch. The advantage of the metal-silicide barrier in the Nb junction process is that it can be etched in $SF_6$ RIE together with Nb electrode. In order to define a junction area precisely and uniformly, end-point detection for the RIE process is critical. In this paper, we employed thin Al layer for the etch stop, and optimized the etch condition. We have successfully demonstrated that the etch stop properties of the inserted Al layer give a uniform etch profile and a precise thickness control of the base electrode in Nb trilayer junctions.

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References

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