Fabrication of metallic structures with lateral dimensions less than 15 nm and jc(T)-measurements in NbN micro- and nanobridges

We report about a process that enables us to manufacture nm-sized structures that are characterized in a four-point resistivity measurement. To define the nanostructures, we employ either a lift-off deposition process or a dry etching process. With the lift-off deposition, we were able to define line widths below 15 nm spatial dimension. The same technique allowed the fabrication of a current-carrying bridge with approximate to 30 nm x 10 nm cross section. The etch-process step allowed us to generate a superconducting meander structure covering an area of approximate to 13.5 mu m x 10.5 mu m. We also present critical-current measurements vs. temperature on sub-mu m and pm sized bridges prepared by a different technique. These data support the idea of a geometrical edge barrier for vortex entry into sub-Pm wide bridges. (C) 2008 Elsevier B.V. All rights reserved.