Development of integrated circuits based on NbN Josephson junctions for 10-K electronics

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K15057
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 21060:Electron device and electronic equipment-related
• Research Institution: National Institute of Information and Communications Technology
• Principal Investigator: Miyajima Shigeyuki 国立研究開発法人情報通信研究機構, 未来ICT研究所フロンティア創造総合研究室, 研究員 (50708055)
• Project Period (FY): 2019-04-01 – 2021-03-31
• Keywords: 超伝導 / 単一磁束量子回路 / 窒化ニオブ

Outline of Final Research Achievements

In this research, we have developed the single-flux-quantum (SFQ) circuits by using NbN-based Josephson junctions (JJs) for establishments of fundamental technology of superconducting electronics operating at 10 K. We proposed a fabrication process and constructed the design environment for the NbN-based SFQ circuits. In order to construct the design environment for NbN-based SFQ circuits, we modified the conventinal design environment for Nb-based SFQ circuits by changing the parameters of JJs, process structure, and so on. We also tried to evaluate the fabricated devices. However, the fabricated circuits were shorted due to the insufficient isolation between NbN wiring layers. We revised the layout design to avoid the circuit short, and we plan to fabricate and evaluate NbN-SFQ circuits again.

Free Research Field

電子工学

Academic Significance and Societal Importance of the Research Achievements

10 Kエレクトロニクスを実現するための新しい回路の設計環境の構築を行い、作製を試みた。結果としては回路の動作評価までには至らなかったが、新しいプロセスを導入した際の回路設計上の問題点等が明らかになった。また、位置精度は0.5μmで作製できているため、現在の作成プロセスの問題点が解決すれば10 Kで動作するNbN-SFQ回路は実現できると考えられるため、本研究を通して10 K動作の超伝導エレクトロニクスの実現に大きく近づいたと考えられる。