Effect of conditioning and slurry application method on silicon dioxide removal rates using a ceria-based chemical mechanical planarization slurry

In this study, the silicon dioxide removal rate using a "reverse" ceria-based slurry was investigated under four different combinations of conditioning modes and slurry application methods. In a "reverse" slurry, addition of water acts to promote material removal. Overall, the process using ex-situ conditioning with the slurry injection system (SIS) resulted the highest removal rate, while the process using in-situ conditioning with the conventional point application (PA) generated lowest removal rate. This study is aimed to explain the differences in silicon dioxide removal rate based on the variations of the actual slurry dilution ratio on top of the pad associated with conditioning and slurry application methods. The frictional analysis and Stribeck+ curves were employed to elucidate the tribological characteristics. The results showed that the conditioning modes and the slurry application methods varied the extent of the polishing vibrations. The silicon dioxide removal rate was found to linearly correlate with the extent of COF fluctuation. This work also underscored the importance of optimum slurry flow dynamics and injection geometry for obtaining a more cost-effective and environmentally benign chemical mechanical planarization process.