Role of mechanically-driven distorted microstructure in mechanochemical removal of silicon

Abstract

Ultra-precision of nanomanufacturing process down to subnanometer level is actually to achieve controllable removal of atomic material, however, which would be strongly impacted by the preconditions of manufactured surfaces. Here, the atomic structures, chemical and mechanical properties of mechanically-driven distorted microstructures on silicon formed in pre-treated process were characterized and their roles in atomic attrition dominated by mechanochemical reactions were revealed at atomic scale. Mechanically deformed silicon depending on applied stress physically behaviors protrusion forming and material removal (groove), which play opposite contributions to the mechanochemical reactions, i.e., atomic attrition suppressed on the protrusion surface but facilitated on the groove surface. Analyzing the mechanochemical reactions with the stress-assisted Arrhenius-type kinetics model and the DMT contact mechanics implies that, compared to the limited effect of the amorphous structure, the enhanced oxide layer at the protrusion surface that increases the energy barrier for mechanochemical reactions plays a more important role in the mechanochemical removal process. The results may help gain a profound insight into the mechanochemical removal mechanism of silicon and provide a wider cognition for regulating the mechanochemical reactions widely existing in scientific and engineering applications.