Preparation of CeO2 Polishing Powder and Its Performance and Mechanism for Chemical Mechanical Polishing of Optical Glass

CeO₂ polishing powder is extensively used in chemical mechanical polishing (CMP) applications on Si substrate materials. This study synthesized sub-micrometer, spherical, fluoride-free, and fluorine-doped CeO₂ particles using the precipitation method at various calcination temperatures. Key parameters of the CeO₂ particles, such as particle size, morphology, crystallinity, and Ce³⁺ content, were obtained using a laser particle size analyzer (LPSA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). In conjunction with CMP experiments on K9 optical glass, the service life and polishing performance were evaluated. It was determined that crystallinity is the most critical factor, with a particularly pronounced role of the (111) crystal plane. Fluorine can enhance crystallinity and promote grain growth; hence, fluorine doping can improve the crystallinity of the powder at relatively low calcination temperatures (600 °C), reducing energy consumption. Additionally, appropriate particle size, rough surface morphology, and hydrophilicity of particles can also contribute to the enhancement of material removal rate (MRR). Fourier transform infrared spectroscopy (FT-IR) confirmed that Ce–O–Si bonding during the CMP process facilitated the disintegration of the glass. XPS verified that some Ce⁴⁺ can be reduced to Ce³⁺ during the CMP process, and the presence of Ce³⁺ can strengthen Ce–O–Si bonding. Ultimately, the glass is primarily removed in a lumped Q³ (Si₂O₅^2– sheet) form through the formation of Ce–O–Si bonds at the CeO₂–glass interface. This study further refines the polishing mechanism of CeO₂ with glass during the CMP process, succinctly summarized in the TOC graphic.