Express-control system of superconducting microcircuits fabrication technology by anodization spectroscopy method

Abstract
The work is concerned to the fabrication technology of superconductive Josephson junctions Nb/A1O_x-Al/Nb and to the development of the anodization spectroscopy method for the express-control system of the technology. We describe the technique of the anodization spectroscopy procedures for estimations of thin films and multilayered structures parameters, such as the thickness of films and interfaces, the oxygen contamination, the degree of nonstoichiometry. It is shown, that anodization spectroscopy is useful to investigate such technological parameters as the uniformity and intensity of deposition, ion etching, oxidation. We have experimentally investigated the correlation between technological conditions, anodization profiles and volt-ampere characteristics of Josephson junctions. It is shown that the optimal technology includes the magnetron deposition (v_Nb = 5.0 nm/s, v_Al = 3.0 nm/s) and oxidation at magnetron plasma. This conclusion is obtained by means of the anodization spectroscopy and confirmed by volt-ampere characteristics. The totality of developed procedures allowed to create the unified express-control system we use for the superconductive technology Nb/AlO_x-Al/Nb. The system may be applied to other thin-film technologies.