Fabrication, characterization, and CMP performance of dendritic mesoporous-silica composite particles with tunable pore sizes

Mesoporous silica (mSiO₂) particles are emerging as one of potential abrasives in high-efficiency and damage-free chemical mechanical planarization (CMP) due to their special mechanical and/or chemical characteristics. In this work, the dendritic meso-silica (D-mSiO₂) shells with tunable pore sizes were uniformly deposited on the solid silica (sSiO₂) core surfaces via a modified biphase stratification approach. As confirmed by FESEM, HRTEM, TEM, and N₂ adsorption-desorption measurements, the obtained spherical sSiO₂/D-mSiO₂ composites with well-defined core/shell structures presented uniform diameter (ca. 340 nm), high surface area (∼210 m²/g), and large pore volume (∼0.3 cm³/g). The average pore size (3.6–11.6 nm) and shell thickness of D-mSiO₂ could be adjusted by varying hydrophobic solvents in the upper oil phases (1-octadecene, decahydronaphthalene, and n-hexane) and amount of silica source. Furthermore, the influence of the pore size of the sSiO₂/D-mSiO₂ composites on oxide-CMP performance was investigated in terms of surface quality and material removal rate. In our experiments, the lowest average surface roughness was obtained for the composites with the largest pore size, which might result from their lowest overall hardness and elastic modulus determined by their largest porosity. In addition, the highest removal rate was achieved when the pore size of the composites was smallest. The enlarged surface area might contribute to enhancing the chemical corrosion, and further promoting the tribo-chemical reactivity between abrasive particles and substrate surfaces. Overall, the presented results are expected to provide experimental and theoretical basis for the structure optimization of mSiO₂-based abrasive particles.