| 摘要 |
PURPOSE:To avoid sputtering of upper electrode material onto a lower electrode and improve reproducibility of superconducting junction current by a method wherein the forming process of the upper electrode material is performed while a substrate holder is covered by a predetermined shielding plate and the forming process of a junction oxide film is performed after the shielding plate is removed. CONSTITUTION:After a substrate 3 is attached to a high frequency electrode 1 and vacuum evacuation is carried out, argon gas is introduced through a gas inlet 4 and a voltage is applied to the high frequency electrode 1 and discharge is induced to clean the surface of the substrate 3. Then oxide gas and argon gas are mixed and introduced and discharge is induced on the electrode 1 to form a junction oxide film on the surface of an NbN lower electrode film. While these discharges are performed, the upper electrode material vapor deposited on a movable shielding plate 6' and a film thickness monitor 5 is kept from being exposed to the discharge plasma. In other words, as a substrate holder 2 is not coated with the upper electrode material, sputtering of the upper electrode material from the holder 2 onto a lower electrode surface is not induced. Successively, after the shielding plate 6' is returned to the position 6 so as to cover the holder 2 except the substrate 3. Pb-Au-In is vapor deposited in vacuum by using an upper electrode evaporation boat 9. |
