HTS edge junction dependence on base electrode edge smoothness

A series of experiments were performed in a Taguchi experimental matrix to examine and compare critical fabrication process factors in junction electr ical performance. Factors such as angle of HTS deposition by pulsed laser d eposition (PLD), pre-cleaning and annealing dwell time prior to epitaxial d epositions, and angle of film edges created by ion milling were examined. T he most critical factor influencing junction performance was the inherent m orphology and smoothness of the base electrode. Based on this we focused on improving base electrode film smoothness. Using this approach we reduced j unction excess current by a factor of 5 to 10 as confirmed by subsequent wa fer fabrications. This improved technique was then integrated into our two- inch wafer process which incorporates automated stepping equipment providin g deep sub-micron layer-to-layer alignment capability.