Preparation and Polishing Properties of Spherical Porous Silica Abrasive

Problem statement: Abrasive is one of key influencing factors on the polished surface quality in Chemical Mechanical Polishing (CMP). Solid abrasives in CMP slurries are easy to cause polishing scratches. It is well known that reducing the hardness of abrasives would improve the polished surface quality. Therefore, the change in structure or shape of the abrasives means a change in polished surface quality. The aim of this research paper is to find the differences of CMP performances on hard disk between solid silica abrasives and porous silica abrasives. Approach: A kind of spherical porous silica abrasive was prepared and its CMP performances on hard disk had been investigated. The influences of polishing parameters including polishing time, down force and rotation speed on Material Removal Rate (MRR) and average roughness (Ra) were studied in hard disk substrate CMP with these prepared spherical porous SBA-15 abrasives and solid silica abrasives. Results: After polished in slurry containing solid SiO₂, the surface became smooth and Ra decreased from 8.234-1.159 nm. However some small scratches still existed there. When polished with slurry containing spherical porous SBA-15 under the same polishing conditions, the surface became smoother, the scratches could hardly be observed and Ra decreased from 8.409-0.539 nm. Conclusion: Compared with solid silica abrasive, the prepared spherical porous silica abrasive has better hard disk substrates CMP performance under the same polishing conditions.