Micropatterning of high-Tc superconducting film by nitrogen ion beam and Ta/resist multilayer mask

Micropatterning of BiSrCaCuO/ss superconducting film is investigated for electronic devices. A combination of nitrogen ion beam and Ta/resist multilayer mask is found to be suitable for achieving micropatterns with sharp edges because of its high selectivity of more than 20. The resist layer enables high-resolution masks to be formed on relatively rough surfaces. Also, an Au protective layer successfully avoids the critical temperature degradation due to oxygen plasma. As a result, BiSrCaCuO microbridges, 1.5-μm wide and 1-μm thick, can be patterned without degradation of the critical temperature and critical current density. Accordingly, these patterning techniques are thought to be useful for fabricating SQUIDs (superconducting quantum interference devices) and microwave components