Preparation,characterization and performance of core-shell PS-CeO2 composite abrasives with different particle sizes

Polystyrene(PS) microspheres were prepared by soap-free emulsion polymerization method.Core-shell structured PS-CeO2 composite microspheres were synthesized by liquid phase process using cerium nitrate and hexamethylene tetramine as raw materials.The composition,phase structure,morphology,grain size and agglomeration of the as-prepared composite microspheres were characterized by XRD,TEM,FESEM,FT-IR and TGA.The as-prepared composite microspheres were collocated into polishing abrasives for chemical mechanical polishing(CMP) of silicon dioxide dielectric layer.The morphologies of the dielectric layer after polishing by the composite abrasives were investigated by AFM.The results indicate that the three kinds of PS microspheres are monodispersive and uniform,and the particle size of PS is about 120,170 and 240 nm,respectively.The particle size of the three kinds of the as-prepared PS-CeO2 composite microspheres is about 140,190 and 260 nm,respectively,and the thickness of CeO2 shell is about 10 nm.After CMP,the surface roughness of SiO2 dielectric layer decreases with the decrease of the particle size of the composite microspheres.The average roughness Ra and root mean square of roughness Rms of dielectric layer polished by PS-CeO2 composite abrasives in the area of 10 μm ×10 μm are 0.372 and 0.470 nm,respectively.