Effect Mechanism of Nano-scratch Speed on Removal Behavior of Single Crystal Silicon

As a typical hard and brittle material, single crystal silicon is strongly influenced by strain rate. And different scratching speeds produce different strain rates, which lead to different removal behaviors. Therefore, molecular dynamics was used to study the deformation and removal processes at different scratching speeds from the perspective of strain rate in this paper. The results showed that the scratching force, shear stress and friction coefficient decreased with the increasing scratching speed due to the increase of the strain rate. In contrast, the scratching temperature rose with the increased scratching speed, which was attributed to the elevated adiabatic effect. As the scratching force and friction coefficient decreased during the scratching, the scratching surface profile accuracy and roughness increased with the growing scratching speed. Amorphization and phase transformation were the main occurrence mechanisms for nanoscale deformation of single crystal silicon during scratching. The reduction of shear stress was the main reason why the depth of subsurface damage layer decreased with the rising scratching speed. The increasing scratching temperature induced by increasing scratching speed led to an improvement in the depth of surface amorphous layer.