Solid-silica core/mesoporous-silica shell composite abrasives: synthesis, characterization, and the effect of mesoporous shell structures on CMP

The silica-based composite abrasive particles containing solid silica (sSiO2) cores and mesoporous silica (mSiO2) shells exhibit potential applications in efficient and damage-free chemical mechanical polishing (CMP) due to their special mechanical and/or chemical characteristics. In this work, the composite particles composed of sSiO2 cores and worm-like mesoporous silica shells (sSiO2/W-mSiO2) or dendritic mesoporous shells (sSiO2/D-mSiO2) were obtained by a modified Stöber method combined with a biphase stratification approach. And the effects of mSiO2 shell structures of the silica-based composites on oxide CMP performance and structural stability were further investigated. TEM and XRD analyses revealed that the sSiO2/W-mSiO2 composites exhibited an improved mesochannel organization in silica shells with respect to the sSiO2/D-mSiO2 particles. The polishing results showed that the substrates after finishing with the as-obtained silica-based composite abrasives presented a superior surface quality with respect to conventional solid silica particles with a comparable particle size. Moreover, an improved organization in silica shells contributed to the improvement of surface quality and mechanical stability during CMP processes. In addition, the sSiO2/D-mSiO2 abrasives exhibited an enhanced material removal rate by comparison with the sSiO2/W-mSiO2 under the same CMP conditions. This work provides an experimental basis for exploring the relationship between the polishing performance and the mesoporous shell structure of silica-based composite abrasives.