Fumed Silica Slurry Stabilizing Methods for Chemical Mechanical Polishing

In order to achieve a low number of polishing defects and to decrease surface roughness on the silicon wafers in chemical mechanical polishing (CMP) technology, the fumed silica slurry settlement method is proposed. Large particles including in the CMP slurry are known to have effects on the polishing defect and the surface roughness on the polished wafer. To stabilize the CMP slurry, the large particles are removed with the settlement separation method, which is a simple method compared to filtration or centrifuge methods. The fumed silica slurry settlement system can selectively remove the large particles which cause scratch defects during CMP. The large particles over 1.0 mum size can be selectively removed after 7 days of sedimentation. The settlement-treated slurry shows good results in terms of the defect levels and surface roughness with the plasma-tetra-ethoxy-silane (p-TEOS) oxide wafer.