A three gun sputtering system for the deposition of superconductor/insulator multilayers

A sputtering deposition system has been developed to grow high-quality superconductor/insulator multilayers specifically for use in fabricating vertically stacked Josephson junctions. A unique feature of the design is the computer control of all parameters involved in the repetitive deposition of multilayers. The computer is interfaced with stepper motors that position the substrate, and shutter wheels. Additional computer controlled stepper motors allow in situ changing of up to five contact masks. The computer is also interfaced to a gas flowmeter that controls the partial pressure of the inert and reactive sputtering gases. High-quality, reproducible multilayer films have been produced and are described. Stacked Josephson junctions have been patterned with the multilayer films and some of their electrical characteristics are presented.