Yield performance in Nanobridge devices: A study of fabrication processes

Nonequilibrium quasiparticles in superconducting quantum devices can be a limiting source of error. One approach for studying these quasiparticles is to trap them in the internal Andreev bound states of an aluminum nanobridge Josephson junction: a thin, narrow, short aluminum bridge (8x20x100 nm) between two superconducting electrodes. Fabricating nanobridge devices, however, presents challenges due to the precision required at such small scales, where even minor deviations can impact device performance. In addition, aluminum films are highly mobile at room temperature and adhere poorly to silicon, leading to strain-induced breakage of nanobridges. To improve yield and optimize fabrication efficiency, it is critical to explore and study nanobridge fabrication processes that may be affecting nanobridge formation and performance. By investigating factors such as resist stacks, lithography techniques, surface treatments, and device temperature during deposition, this study aims to identify key areas of improvement in nanobridge fabrication to maximize yield and reliability for nanobridge testing and application.