Nonorganic evaporation mask for superconducting nanodevices

We describe a novel technique to produce submicron thin film structures of high melting superconducting materials (Nb). The method is based on a nonorganic evaporation mask (Si3N4) to avoid any outgassing of the mask material during the metal deposition which would deteriorate the superconducting properties of the Nb. The mask has a large offset from the substrate so that clean interfaces of different materials (e.g. normal metal/superconductor (NS)) can be achieved by angle evaporation in one single process step. By this means we have prepared narrow Nb wires with high transition temperature and NS structures with high quality interfaces.