Atomistic mechanisms of SiC electrochemical mechanical polishing in aqueous H₂O₂: A ReaxFF molecular dynamics study

Molecular dynamics (MD) simulations using the reactive force field (ReaxFF) were conducted to investigate the atomic-level scratch removal process on silicon carbide (SiC) (001) substrates during electrochemical mechanical polishing (ECMP). Diamond abrasive particles were employed in an aqueous hydrogen peroxide (H₂O₂) solution, and an electric field was applied to elucidate the atomic-scale processes during the ECMP of SiC. The research findings indicate that the application of an electric field alters the charge distribution of surface atoms on SiC (001) substrates. At 20 V, the charge of the electro-oxidized Si atoms is 0.094 e higher than that at 0 V, which significantly increases the electrochemical activity and accelerates the oxidation process of the SiC surface. In addition, under 20 V, the maximum penetration depth of oxygen (O) atoms is 2.1433 Å, which is 2.15 times that under no voltage conditions; the final number of Si-OH bonds is 301, which is 1.53 times that under no voltage conditions. Macroscopic experimental observations were compared and analyzed with the simulation results through X-ray Photoelectron Spectroscopy (XPS) and focused-ion-beam (FIB) cross-sectional analysis. The simulation results are consistent with the chemical friction and wear behavior of SiC shown in the experiment, which indirectly confirms the accuracy and reliability of the simulation results from the perspective of the chemical action mechanism of ECMP. This study provides valuable insights into the atomistic mechanisms and optimization strategies for the ECMP of SiC.