an improved microfabrication technique for josephson junctions in superconducting integrated circuits , based on the use of a double - layer lithographic mask for partial anodization of the side - walls and base electrode of the junctions . the top layer of the mask is a resist material , and the bottom layer is a dielectric material chosen so to maximize adhesion between the resist and the underlying superconducting layer , be etch - compatible with the underlying superconducting layer , and be insoluble in the resist and anodization processing chemistries . the superconductor is preferably niobium , under a silicon dioxide layer , with a conventional photoresist or electron - beam resist as the top layer . this combination results in a substantial increase in the fabrication yield of high - density superconducting integrated circuits , increase in junction uniformity and reduction in defect density . a dry etch more compatible with microlithography may be employed .