Ti quadlevel resist process for the fabrication of Nb SIS junctions

We have fabricated high quality Nb/Al-oxide/Nb Superconductor-Insulator-Superconductor (SIS) junctions using a Ti-based quadlevel resist process. The quadlevel materials have been carefully chosen to optimize the fluorine-based anisotropic reactive ion etching of Nb and subsequent insulation coverage of the junctions in a self-aligned process. This SIS fabrication process enables excellent control of junction size and is also compatible with Au overlayer junction and junction anodization approaches.