Synthesis and characterization of nanoporous silicon dioxide particulate for low defectivity in low-k dielectric chemical mechanical polishing

The abrasive particles in the chemical mechanical polishing (CMP) slurries play a critical role in controlling the yield of semiconductor devices. The state-of-the-art of CMP slurries typically employs hard abrasives such as alumina or silica which can lead to the significant surface defects during polishing. These surface defects during CMP are serious problems for the integration in interconnect structures. To reduce the surface defects, a new slurry design is required.; We have studied the nanoporous silica particles which are expected to reduce surface defects in low-k dielectric CMP process. By controlling the particle size and porosity, the surface properties of the particles can be suitably modified. Using these particles in the CMP slurries, we can reduce defectivity in low-k dielectric polishing. For this work, the spherical nanoporous silica particles with controlled particle size and surface porosity have been prepared by a precipitation technique and characterized in terms of optical, electrical, and mechanical properties. We also have inspected the surface defects of wafers polished in nanoporous silica particle based slurry systems under AFM and SEM, which has proven that the nanoporous silica particles enable a reduction of the surface defects in the CMP process.