Silica abrasives containing solid cores and mesoporous shells: Synthesis, characterization and polishing behavior for SiO2 film

Abstract

Oxide porous microspheres as novel abrasives have potential application in efficient and non-damage chemical mechanical polishing (CMP) due to their uniform mechanical and/or absorption properties. In this work, solid silica (sSiO2) cores were coated with mesoporous silica (mSiO2) shells via a modified Stöber method using vinyltrimethoxysilane as silica source and cetyltrimethylammonium bromide as structure directing agent. The obtained allotropic silica (sSiO2/mSiO2) samples were characterized by Fourier transform infrared spectroscopy, thermogravimetric analyzer, transmission electron microscopy, field emission scanning electronic microscopy and N2 adsorption–desorption. The effects of the thickness of mSiO2 shell on the CMP behavior for silicon dioxide films were evaluated by atomic force microscopy. The CMP results indicated that the as-prepared sSiO2/mSiO2 abrasives presented a much higher material removal rate, lower surface roughness as well as lower topographical variations than those of traditional solid silica abrasives. Furthermore, the material removal rate and surface roughness increased with the increase of the thickness of mSiO2 shell. The enhanced polishing performance might be contributed to the improvement of the physical and/or chemical environments in the local contacting region between abrasives and wafers. According to the indentation-based mechanism, these oxide-CMP results were rationalized from both chemical corrosion and mechanical abrasion actions. This work constructed a relationship between polishing behavior and microstructure of novel allotropic silica abrasives.