Nano-polishing characteristics in vibration-assisted CMP of single-crystal silicon carbide via molecular dynamics simulations

Abstract

Vibration-assisted CMP can effectively improve the quality and efficiency of nano-polishing, but the mechanism of the interaction between the substrate, solution and abrasive atoms has not been thoroughly investigated. In this paper, a single-crystal silicon carbide material was taken as an example. The characteristics of atomic oxidation, removal and damage on nano-polished silicon carbide substrate under the assistance of chemical solution and abrasive vibration were studied using ReaxFF molecular dynamics simulation. The simulation results show that the vibration behavior of abrasive reduces the tangential and normal force, and evenly distributes the mechanical force in X, Y and Z directions. Moreover, the anisotropy of the atomic motion trajectory is stronger, the displacement vector is larger, and the distribution of displacement values is more dispersed. In addition, the phenomenon of atomic hybridization on the silicon carbide substrate is more obvious, the number of dangling bonds is significantly increased, the surface of the substrate formed more oxidation bonds, the removal of atoms is also effectively increased. At the same time, it is found that the larger the amplitude, the larger the potential energy of the substrate, the more dangling bonds contained, the more oxidation bonds formed, the more atoms removed, the better the uniformity of the force component. As the normal force is effectively reduced, the damage degree of substrate subsurface is reduced. Increasing the frequency can effectively activate the internal structure of the crystal, reduce the damage caused by mechanical abrasion, and facilitate the oxidation and removal of substrate atoms. However, if the frequency is too high, the interaction time between the substrate and the abrasive decreases, and the substrate atomic displacement is prone to elastic recovery, which inhibits atomic detachment from the substrate. Furthermore, the stress concentration generated by the accumulation of defects inside the substrate is more severe, making it difficult to release the residual stress. This paper will provide a new way to optimize the vibration-assisted CMP process and achieve non-damage nano-polishing of crystal materials through the study of the micro-oxidation and removal behavior of the substrate atoms.