Synthesis of non-rigid core–shell structured PS/SiO2 composite abrasives and their oxide CMP performance

The positively charged PS microspheres were prepared via soap-free emulsion polymerization method by using azobisisobutyronitrile (AIBN) as initiator. Tetraethylorthosilicate (TEOS) hydrolysis catalyzed and the negatively charged SiO2 could be absorbed onto the surfaces of the positively charged PS microspheres. The microstructures of the composites were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), fourier transform infrared spectrum (FT-IR), and X-ray diffraction (XRD). The composites were collocated into polishing slurries for the chemical mechanical polishing (CMP) of silicon dioxide dielectric layer. The dielectric layers were investigated by atomic force microscope (AFM). The results indicated that the particle size of composites is about 550 nm, and the PS microsphere is uniformly coated by SiO2 shell (about 20 nm in thickness). After CMP, the composite abrasives led to lower topographical variations and surface roughness, compared with pure SiO2 abrasives and PS microspheres. The root mean square (RMS) value within 5 × 5 μm area of dielectric layer polished by PS/SiO2 composite abrasives is 0.209 nm, and the material removal rate (MRR) can reach 367.1 ± 48.0 nm/min.

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► The positively charged PS microspheres were prepared by using azobisisobutyronitrile (AIBN) as initiator.
► The SiO2 could be absorbed onto the surfaces PS microspheres attributed to positively–negatively charged interaction.
► The SiO2 shell completely appeared as an amorphous structure around the PS core, rather not particle state.
► We firstly applied the novel core–shell structured PS/SiO2 composite abrasives to improve oxide CMP performance.