Construction of a Ce–F Bond in CeO2–xFx Nanoabrasives and Its Dispersion-Polishing Coupling Enhancement Mechanism

Abstract

As a commonly used abrasive in chemical mechanical polishing (CMP), CeO₂ enables high-precision material removal during SiO₂ polishing due to its unique chemical tooth effect. Its performance is heavily influenced by the dispersion stability of the polishing slurry and the concentration of Ce³⁺ in the CeO₂ particles. Traditional methods that rely on dispersant additives have inherent limitations, including sensitivity to environmental factors such as pH and temperature, which can lead to dispersant failure and particle reagglomeration, thereby compromising polishing uniformity. Additionally, excessive dispersant may coat the abrasive surfaces, reducing direct contact with the workpiece and, consequently, diminishing the material removal rate (MRR) and chemical activity. To overcome these challenges, this study proposes a fluorine doping strategy that enhances both the Ce³⁺ concentration and dispersion stability by precisely controlling the F^– doping levels in CeO₂ abrasives. Experimental results show that fluorine doping significantly improves the colloidal stability, as evidenced by a reduced sedimentation rate, an increased optical absorbance, a higher zeta potential (63.1 mV), and a more uniform particle size distribution with suppressed agglomeration. These changes enhance the effective contact area between the abrasives and SiO₂ substrates. Notably, at an optimal F^– doping concentration of 0.05, the modified abrasives exhibited a 12.28% increase in surface oxygen vacancy density and Ce³⁺ concentration compared to the undoped abrasives, alongside a 31% improvement in SiO₂ MRR. Furthermore, the polishing mechanism of the doped abrasives on SiO₂ substrates was systematically investigated, revealing an enhanced chemical–mechanical synergy through controlled oxygen vacancy generation and optimized surface charge characteristics.