Josephson integrated circuit

Abstract

Abstract PURPOSE:To facilitate the heat sink of a Josephson junction and a resistance element by surface treating an aluminum surface with plasma by mixture gas of CF4 and O2, thereby forming a dense insulating layer having less defects and forming the aluminum layer under these compounds in thermal conductive state. CONSTITUTION:An Nb film is formed by a vacuum deposition method on a sapphire substrate 1, and a lower electrode 2 is formed by etching. After a lift-off mask 3 is then formed of photoresist, an aluminum film 4 is deposited. Subsequently, an AlF3 layer 5 is formed on the surface of the Al film with RF plasma of the mixture gas of CF4 and O2. In this manner, an insulating layer made of two-layer films of Al and AlF3. After the lift-off method, the patterns of Si 6 to become a barrier and Pb 7 to become an upper electrode are simultaneously formed by a lift-off method. No shortcircuit occurs between the two superconductive electrodes, and no decrease in the circuit characteristics occurs due to the heat of the Josephson junction and the resistance element, thereby improving the reliability of the element and the stability of the circuit operation.

Inventors

• 👤 Juichi Nishino
• 👤 西野　寿一
• 👤 Junji Shigeta
• 👤 淳二 重田
• 👤 Koji Yamada
• 👤 宏治 山田
• 👤 Kunio Yamashita
• 👤 山下　邦男
• 👤 Mikio Hirano
• 👤 幹夫 平野
• 👤 Shinichiro Yano
• 👤 振一郎 矢野

Bibliographic Details