Effect of gradient polishing depth on material removal mechanism of silicon wafer polishing by silicon dioxide abrasive based on molecular dynamics

To study the effect of gradient polishing depth on the material removal mechanism of silicon wafers, the LAMMPS molecular dynamics method is utilized, combined with Lennard-Jones (LJ), Tersoff, and StillingerWeber (SW) potential functions. The nano-polishing process is investigated through gradient depth polishing experiments, with five different polishing depths of 2.2 nm, 2.4 nm, 2.6 nm, 2.8 nm, and 3.0 nm selected for analysis. By analyzing physical quantities such as polishing force, crystal structure, dislocation, radial distribution function, and coordination number, the effect of gradient polishing on material removal is revealed. The results show that at a polishing depth of 2.6 nm, the polishing force is stable, and the surface roughness reaches its minimum value (Sa = 8.109 nm). Subsurface damage is minimized, and the Si-I phase structure remains intact, avoiding amorphization and phase transformation. This depth effectively removes material while preserving surface quality, making it the ideal polishing depth for enhanced processing efficiency. At polishing depths of 2.2-2.4 nm, shear strain begins to concentrate, and surface roughness starts to decrease. When the polishing depth increases to 2.4 nm, subsurface damage intensifies, and the roughness value becomes Sa = 10.01 nm. At polishing depths of 2.8-3.0 nm, roughness reaches its highest value (Sa = 11.843 nm), and the original silicon wafer structure Si-I transforms into Si-II phase, bct5-Si phase, and an amorphous state due to extrusion and shearing, resulting in decreased surface quality. This study provides an important theoretical foundation and practical guidance for optimizing the polishing process of silicon wafers and improving material removal efficiency and surface quality.