Enhanced local oxidation of silicon using a conducting atomic force microscope in water

A new mechanism for direct-write surface scanning probe lithography is considered based on electrodynamic cavitation in a true liquid environment. Oxide layers grown on Si/SiO₂/H₂O and Si/SiO₂/Au/H₂O interfaces reached maximum heights of 130 and 690 nm, respectively. These structures represent a full order of magnitude increase in height over oxides grown in air under similar voltages and time durations, suggesting a unique reaction mechanism. Time-dependent studies indicated that oxide structures generated in water grew by discrete intervals and occasionally grew at a significant distance from the tip, effects that have not been previously reported. The possibility of electrodynamic cavitation-assisting silicon oxide growth under aqueous conditions is considered, potentially opening up opportunities for formation of nanoscale surface structures based on largely underutilized cavitation-induced (e.g., sonochemical) reactions.