Cerium oxide (CeO₂) is a critical abrasive in chemical mechanical polishing (CMP), a key technology for achieving planarization in semiconductor manufacturing. Its Ce³⁺/Ce⁴⁺ redox couple and abundant oxygen vacancies enable superior surface finishes and material removal rates. However, conventional synthesis methods often suffer from poor morphology control or complex processing steps, limiting their practicality in semiconductorgrade applications.
In a study published in ENG. Chem. Eng., researchers report a simple, surfactantfree hydrothermal strategy for synthesizing spherical CeO₂ abrasives with controllable particle size. By adjusting the water volume during synthesis, particle size was precisely tuned from 32 to 531 nm while preserving excellent sphericity and dispersity.
The formation mechanism was elucidated through GCMS analysis and thermodynamic calculations. During hydrothermal treatment, nitrate oxidizes Ce³⁺ to Ce⁴⁺, producing NO and NO₂ gases. The Ce⁴⁺ then reacts with acetate to precipitate CeO₂, releasing CH₄ and CO₂. While the individual oxidation reactions are thermodynamically unfavorable, coupling them with CeO₂ precipitation drives the overall process forward. Increasing water volume dilutes ethylene glycol and acetic acid, weakening their capping and structuredirecting effects and lowering the nucleation rate, which results in fewer nuclei and enhanced particle growth – leading to larger particle sizes.
XRD confirmed the fluorite structure of the synthesized CeO₂, with diffraction peaks matching JCPDS No. 340394. HRTEM revealed lattice fringes with dspacings of 0.312 nm and 0.271 nm, corresponding to the (111) and (200) planes, respectively. The particles maintained spherical morphology across all sizes, with narrow size distribution (D₉₀−D₁₀)/2D₅₀ < 0.5.
CMP tests on silicon wafers showed that MRR increased with particle size, reaching a maximum of 73.7 nm·min⁻¹ at 343 nm, while surface roughness (Ra) remained between 0.3 and 0.4 nm across the entire size range (32–531 nm). This contrasts with conventional observations where larger particles typically cause more scratches; the uniform spherical morphology ensures even force distribution, minimizing defects.
Optimization of abrasive concentration revealed that 0.5 wt% CeO₂ achieved the best balance between removal efficiency and surface quality, reducing Ra from 1.93 nm (untreated) to 0.31 nm – an 84 % improvement. Higher concentrations (≥1.0 wt%) led to abrasive residue and increased roughness. Polishing time studies showed that Ra decreased with time, reaching a minimum of 0.30 nm at 15 min.
Compared to commercial CeO₂ abrasives (81 nm, (D₉₀−D₁₀)/2D₅₀ = 0.32), the synthesized abrasives (65 nm, (D₉₀−D₁₀)/2D₅₀ = 0.28) achieved lower surface roughness at both 5 min (Ra = 0.52 vs. 1.01 nm) and 15 min (Ra = 0.32 vs. 0.45 nm), with comparable or slightly higher MRR. The superior performance arises from the excellent size uniformity and spherical morphology, which enable consistent contact and smooth abrasive motion.
This work demonstrates a simple, effective, and scalable strategy for synthesizing sizecontrolled CeO₂ abrasives with superior CMP performance for precision surface processing.

DOI
10.1007/s11705-026-2672-4