| 摘要 |
PURPOSE:To make it possible to make stable rf discharge and to form a tunnel barrier layer whose permittivity is low, by performing sputtering etching of a substrate electrode in the mixed gas of two or more gases selected among He, Ne, and Ar and CF4 gas under a specified gas pressure. CONSTITUTION:The tunnel type Josephson junction element, wherein an Nb- Al superconducting thin film is used, is manufactured as the substrate. At this time, the sputtering etching of the substrate electrode is performed in the mixed gas of the two or more gases selected among He, Ne, and Ar and the CF4 gas under the gas pressure of 0.1-0.005Torr. Thereafter oxidation is performed and the tunnel barrier layer is formed. Then, the stable discharge is made possible when the sputtering is performed, and the contamination of the surface of the substrate due to the back sputtering is prevented. An Al rich layer is formed on the surface of the thin film by the difference in the sputtering of Al and Nb due to CF4. Thereafter, the surface of said layer is oxidized, and the Al2O3 tunnel barrier layer having low permittivity is formed. |
