Atomistic mechanisms of Si chemical mechanical polishing in aqueous H2O2: ReaxFF reactive molecular dynamics simulations
JL Wen and TB Ma and WW Zhang and ACT van Duin and XC Lu, COMPUTATIONAL MATERIALS SCIENCE, 131, 230-238 (2017).
ReaxFF reactive molecular dynamics simulations are employed to study the process of the silica abrasive particle sliding on the Si (100) 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-O-Si bridge bonds due to the chemical reactions at the interface. Under the mechanical sliding effects, the Si-Si and Si-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. (C) 2017 Elsevier B.V. All rights reserved.
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