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Employing Al Etch Stop Layer for Nb-based SNS Josephson Junction Fabrication Process  

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)
Publication Information
Progress in Superconductivity / v.12, no.2, 2011 , pp. 114-117 More about this Journal
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.
Keywords
Josephson junction; Etch stop; Reactive Ion Etch; Multilayer;
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