Atomistic mechanisms of Si chemical mechanical polishing in aqueous H₂O₂: ReaxFF reactive molecular dynamics simulations

ReaxFF reactive molecular dynamics simulations are employed to study the process of the silica abrasive particle sliding on the Si (1 0 0) substrate in the aqueous H₂O₂ in order to clarify the atomistic mechanisms of the Si chemical mechanical polishing (CMP) process. Our results reveal that the mechanical sliding effects induced chemical reactions at the abrasive particle and Si substrate interface dominate the CMP process and lead to the removal of Si atoms. Before the abrasive particle and Si substrate surface interact mechanically, aqueous H₂O₂ can make the Si substrate more oxidized. Once they contact with each other, they are connected by the interfacial Si[sbnd]O[sbnd]Si bridge bonds due to the chemical reactions at the interface. Under the mechanical sliding effects, the Si[sbnd]Si and Si[sbnd]O bonds on the Si substrate can be mechanically strained to be broken, leading to the removal of Si atoms from the Si substrate. Compared with the CMP process in pure H₂O, the CMP process in the aqueous H₂O₂ leads to more oxidized substrate and the removal of more Si atoms, demonstrating the significant role of H₂O₂ as an oxidizer. Besides, the friction force is higher than that in the pure H₂O case due to the stronger interfacial covalent bonds formation and breaking. Our results may shed light on the removal mechanism of Si atoms in the CMP process at the atomic level and provide an effective method to help design the components of the CMP slurry.