Optimization of shadow evaporation and oxidation for reproducible quantum Josephson junction circuits

Shadow evaporation of Josephson junctions

During electron-beam evaporation of Josephson junctions a diverging metal flow is formed (Fig. 1a). Its conical shape leads to nanoscale misalignment of junction electrode positions over a wafer and changes in electrode linear dimensions. One can imagine this effect as changing deposition angle over the wafer—from the center point of the wafer to edges. The changing angle results in a different shading of a metal flow from a two-layer resist mask edge. Additionally, it also affects thickness fluctuations of shadow evaporated aluminum electrodes…