Preparation of Al2O3@CeO2 core–shell composite abrasives and their effect on the chemical mechanical polishing performance of SiC

Herein, Al 2 O 3 @CeO 2 core–shell composite abrasives were prepared for the chemical mechanical polishing (CMP) of 4H-SiC. The abrasives achieved a high material removal rate with low surface roughness due to CeO 2 deposition on the spherical Al 2 O 3 particles (cores) using a liquid-phase deposition method. The effects of Ce precursor dosage on the abrasive structure, dispersion characteristics, and CMP performance were investigated. Results indicated that the Ce precursor dosage strongly influenced the surface structure and dispersion behavior of the composite abrasives. At a Ce precursor dosage of 0.3 g, the resulting composite abrasive (AC2) exhibited a uniform CeO 2 shell and excellent particle dispersion in polishing slurry. When used to polish SiC wafers, AC2 achieved a surface roughness as low as 0.170 nm and a material removal rate of 1067 nm/h, representing a 39.5% increase compared with that of pure Al 2 O 3 abrasives. The core–shell configuration integrates the mechanical removal capability of Al 2 O 3 with the surface chemical activity of CeO 2 , providing a strategy for balancing material removal efficiency and surface quality during the CMP of 4H-SiC wafers. Combined analyses using transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, particle-size distribution, and zeta-potential measurements, together with CMP performance evaluation, revealed a clear relation among abrasive structure, surface chemistry, dispersion behavior, and CMP performance. The CeO 2 shell provided a chemically active surface associated with the coexistence of Ce 3+ and Ce 4+ species, whereas the Al 2 O 3 core provided the mechanical capability required for material removal. The integration of these complementary functions contributed synergistically to the favorable CMP performance of the composite abrasive. This core–shell structure effectively prevented hard-contact scratching and considerably improved the surface quality of 4H-SiC wafers. Thus, Al 2 O 3 @CeO 2 core–shell composite abrasives are ideal for the efficient and low-damage planarization of third-generation semiconductor SiC wafers.