This paper presents a resist-less process for parallel fabrication of sub-micrometer Al-AlOx-Al superconducting tunnel junctions. A custom stencil is fabricated containing 200 nm low-stress SiN membranes with micro-apertures. The stencil is aligned and clamped with a 1 mum accuracy to a substrate wafer containing Ti-Au contact electrodes. The junctions are fabricated by evaporating Al from two different angles, with an intermediate in-situ oxidation step. Measurements of the devices down to 0.3 K show stencil lithography is a good candidate for parallel, resist-less patterning of sub-micrometer area tunnel junctions. Challenges are addressed and further developments are proposed.
- Shadow mask
- Stencil lithography
- Superconducting tunnel junction
Savu, V., Kivioja, J., Ahopelto, J., & Brugger, J. (2009). Quick and clean: Stencil lithography for wafer-scale fabrication of superconducting tunnel junctions. IEEE Transactions on Applied Superconductivity, 19(3), 242-244. https://doi.org/10.1109/TASC.2009.2019075