ReaxFF molecular dynamics of chemical reaction mechanism of SiC crystal with alcoholic additives in CMP

L He and J Li and C Tang and K Chen and LT Yang and JL Si, COMPUTATIONAL MATERIALS SCIENCE, 258, 114026 (2025).

DOI: 10.1016/j.commatsci.2025.114026

Due to wide forbidden band, high thermal conductivity and large breakdown field strength, single crystal silicon carbide (SiC) is widely used in many fields such as aerospace and new energy vehicles. Chemical mechanical polishing (CMP) is the main way to realize the flattening of SiC crystal surface, in which the chemical reaction between the slurry and SiC crystal surface is one of the important factors affecting the wafer surface quality and material removal. The high chemical inertness of SiC crystal makes it extremely difficult for chemical reactions to occur on its surface. Although alcohol additives are outstanding in chemical mechanical polishing of SiC crystal, but the specific chemical reaction mechanism is unclear. In this study, ReaxFF molecular dynamics simulation is used to investigate the chemical reaction mechanism of alcohol additives with SiC crystal surfaces after scratching. It is found that the chemical oxidizing activity of alcohol additives on the SiC crystal surface is in the following order from strong to weak: ethylene glycol > methanol > ethanol > water. The additive molecules react with SiC crystal by dissociative adsorption and hydroxyl bonding to Si atoms to form Si-O-Si bonds, resulting in a softened layer. The softened layer is then removed by the mechanical action of the polishing pad. Fixed abrasive chemical mechanical polishing of SiC crystal is carried out, and the reaction mechanism of water-based alcohol additives with SiC crystal is proposed in combination with ReaxFF molecular dynamics simulation results. A reference is provided for the subsequent mechanism study of SiC crystal CMP process.

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