Abstract: Composite polystyrene-core ceria-shell abrasives are synthesized by direct chemical deposition reaction of Ce(NO3)3 and C6H12N4 on the surface of negative-charged polystyrene (PS) microsphere. The CeO2 shell thickness of composite abrasives can be tuned by changing the concentration of Ce(NO3)3 in the reaction solution. The as-synthesized samples are characterized by techniques of transmission electron microscope (TEM), field emission scanning electron microscope (FESEM), Raman spectroscope (RS), thermogravimetric analysis(TGA)and dynamic light scattering (DLS) measurements. Effects of the CeO2 shell thickness of PS/CeO2 composite abrasives on oxide chemical mechanical polishing (CMP) performance are also investigated by using atomic force microscope (AFM). The results indicate that the core-shell structured PS/CeO2 composite abrasives are in regular spherical shape with a diameter of 200～250 nm, and the shell thickness is about 10～30 nm. The CMP test results confirm that there is an obvious effect of the shell thickness of composite abrasives on oxide CMP behavior. The CMP performance is better and then worse with the increase of shell thickness from 10 to 30 nm. When the CeO2 shell thickness is 20 nm, Ra and root-mean-square roughness within 5 μm×5 μm area of thermal oxide film surface after polishing is 0.196 and 0.254 nm respectively. Moreover, the material removal rate can reach to 568.2 nm/min.

Key words: Ceria, Composite abrasive, Core-shell structure, Polishing, Shell thickness