Atomic-scale study on particle movement mechanism during silicon substrate cleaning using ReaxFF MD

Abstract

The cleaning of silicon wafer surfaces in the integrated circuits manufacturing has not yet been studied at the atomic scale, making it difficult to optimize. In this study, the atomistic mechanism of nanoparticle movement during the cleaning process of the substrate after chemical mechanical polishing (CMP) was investigated using ReaxFF reactive molecular dynamics simulations. The redeposition and removal processes of the silica nanoparticles on the Si (100) substrate with different ambient humidity and substrate state were simulated. Results indicated that water generally plays a positive role in cleaning process, preventing the silica nanoparticles from approaching the substrate and promoting the fracture of interfacial chemical bonds, and it also mitigates the substrate damage caused by particle removal. Aqueous H2O2 influences the substrate state by increasing the oxidizability and hydroxylation level of the substrate surface, which changes the interaction force between the substrate and the nanoparticles, thus impacting particle redeposition process. Additionally, the peroxide facilitates the formation of Si–O–Si bonds and inhibits the removal of the nanoparticles. This work provides atomistic insights into the wafer cleaning process, which is of great significance for the solution design.