Increase in Ce³⁺Concentration of Ceria Nanoparticles for High Removal Rate of SiO₂in Chemical Mechanical Planarization

Ceria nanoparticles (NPs) are used as abrasives for silicon dioxide (SiO 2 ) chemical mechanical planarization (CMP) due to the strong chemical bonds between the Ce 3+ ions of ceria NPs and the hydrated silicate species on the surface of SiO 2 films. However, the limited concentration of Ce 3+ ions in ceria NPs remains a major challenge for this application. Herein, we report a simple strategy to synthesize ceria NPs with high concentrations of Ce 3+ ions for enhanced adsorption reactions with silicate anions. Three types of ceria NPs approximately 70 nm in size were synthesized via the aggregation of different sized primary NPs. As the particle size of the primary NPs decreased from 70 nm to 5 nm, the Ce 3+ concentration of the ceria NPs increased from 15.6 to 24.0%. The adsorption isotherm fits the Freundlich model and the constants of adsorption capacity (K F ) and adsorption intensity (1/n) indicate that the adsorption affinity for silicate anions increased with increasing Ce 3+ concentration. The increase in Ce 3+ concentration led to an increase in the chemical adsorption between ceria NPs and silicate anions, resulting in a high removal rate of SiO 2 during CMP.