Cryogenic Mobility Enhancement in Si MOS Devices via SiO2 Regrowth

Cryogenic mobility enhancement, corres- ponding to the reduction of interfacial disorder, is always a research focus in Si-based MOS device manufacturing toward practical quantum computing chips. In this work, we report the dependency of MOSFET cryogenic mobility on reactive ion etching (RIE)-induced damages at 5–75 K. We discover that RIE will introduce a lot of atomic steps and charged traps at SiO₂/Si interfaces or conducting channel boundaries during the mesa formation stage, severely degrading device mobility, especially at a low temperature. With a post-RIE high-temperature SiO₂ regrowth process, the device cryogenic (1.8 K) peak mobility is enhanced to ~20314 cm²/( $Vs$ ) at a small electron density of $1.05\times10$ ¹²/cm², meaning the successful removal of RIE-induced extra effective scattering centers within the optimized device. Notably, our work presents the adverse impacts of RIE on MOS device cryogenic mobilities and provides a feasible integration flow to recover device performances, which may promote the evolution of Si-based MOS quantum dot computation.