MANUFACTURE OF JOSEPHSON INTEGRATED CIRCUIT

PURPOSE:To form a superconducting electrode made of a high-melting point metal with excellent reproducibility by using a lift-off mask having three-layer structure. CONSTITUTION:When SiO5 is evaporated and lifted off by acetone, the reverse pattern of SiO is obtained. When Al3 is etched by the mixed liquid of phosphoric acid, nitric acid, glacial acetic acid and water and a photo-resist 2 as the lowermost layer is exposed and developed while using the pattern of the Al3 as a photo-mask, the lift-off mask is completed. The superconducting electrode is formed by employing the mask. A substrate is coated with Nb through electron beam evaporation. Lift-off is easily executed by immersing the substrate into acetone, the superconducting electrode pattern of Nb can be shaped with excellent size accuracy, and reproducibility is also superior.