Contact technique for electrical circuitry

Abstract

In electrical circuitry, and particularly superconducting circuitry including Josephson tunnelling devices, it is often necessary to provide solder contacts to electrical lines, where the electical lines would be destroyed if there were interdiffusion between the lines and the solder. To avoid this problem, a laterally extending metallic layer is used as a diffusion barrier between the solder land and the electrical line which can be a superconducting line. The diffusion barrier is comprised of a refractory metal which has a first portion electrically contacting the solder land and a second, laterally displaced portion, electrically contacting the electrical line. An insulating protective layer on the diffusion barrier layer separates the solder land and the electrical line. In a specific embodiment, the superconducting electrical line is comprised of an alloy of lead while the diffusion barrier is comprised of niobium, and the solder alloy is a low melting point alloy, typically comprised of indium, bismuth, and tin.

Dependencies are inferred from the claim text.