Cerium contamination on silicon carbide optics during CMP: TOF-SIMS, XPS characterization, and ReaxFF MD simulation

YJ Li and LX Li and HD Wei and XC Li and YR Wang and S Pan and XJ Zhang, APPLIED SURFACE SCIENCE, 703, 163390 (2025).

DOI: 10.1016/j.apsusc.2025.163390

Silicon carbide mirrors, prized for their ultralight weight, high thermal conductivity, and stiffness, are wellsuited for high-power laser systems; however, cerium contamination from chemical mechanical polishing (CMP) limits their practical use. This study combines multi- scale characterization and molecular dynamics simulations to investigate the formation and distribution of cerium contamination during CMP. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to analyze residual contaminants and interface morphology changes. X-ray photoelectron spectroscopy (XPS) and time-of- flight secondary ion mass spectrometry (TOF-SIMS) enabled the precise localization of the chemical states and three-dimensional distribution of cerium species. Reactive Force Field (ReaxFF) molecular dynamics (MD) simulations were employed to clarify the bonding interactions between cerium contaminants and the substrate at the atomic scale. The results demonstrate that cerium contamination persists on the surface and extends to 31 nm within the mirror, with its intensity decreasing exponentially with depth. Ce-O-Si bonds are formed between cerium oxide and the mirror, which primarily leads to cerium deposition. Additionally, ion beam finishing has been demonstrated to remove cerium contaminants effectively. This study provides guidance for the precise removal of residual cerium contaminants, facilitating the broader application of silicon carbide mirrors in high-power laser systems.

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