SUPERCONDUCTING SUBMICRON BRIDGES FABRICATED BY ELECTRON-BEAM LITHOGRAPHY AND DRY ETCHING

We have developed a three-level-based PMMA/Ti/Pt resist system for the fabrication of high T(c) superconducting structures with lateral dime nsions in the 100nm region. The degradation of superconductivity after substractive sub-mu patterning of high T(c) YBCO-films is minimized. in order to perform conductance measurements, where large contact pads have to be attached to submicron bridges, high resolution electron be am lithography has been combined with optical lithography. Thereby, th e YBCO-film remains protected by the bottom platinium layer until the final ion milling step. As a result, bridges with a linewidth down to 150 - 200nm and up to several mum in length have been fabricated, whic h retain their superconductivity even without oxygen reloading.