Device fabrication by nanolithography and electroplating for magnetic flux quantization measurements

100-keV e-beam lithography and electroplating of gold have been used to fabricate a device for the measurement of quantum changes in magnetic flux. The structure is defined in a 200-nm-thick layer of a copolymer of methyl methacrylate and methacrylic acid (PMMA/MAA) on top of a Si wafer covered by 150 nm of Si3N4. The device is a square frame of 2×2 μm2 and 100-nm linewidth. Gold was electroplated to a thickness of 100 nm. This technique allows the fabrication of high resolution, high aspect ratio gold structures.