Analytical and functional characterization of recycled fumed silica slurries in ILD CMP

CMP (Chemical and Mechanical Flanarization) technology has played an enabling role in attaining nearperfect planarity of interconnection and metal layers essential for the realization, and miniaturization of high-performance devices. In order to ensure stable and high-performance CMP characteristics, optimization of the slurry, the pad and other consumables is critical. Additionally, the relatively high cost of ownership associated with CMP consumables warrants novel approaches to reduce these expenses. Previous studies have demonstrated the feasibility of regenerating slurry. One study in particular showed that high purity colloidal silica was recommendable for a reclaim use because of its higher dispersion and less clogging nature compared to fumed silica. For this reason, fumed silica slurry was chosen for the study. The goals were to characterize regenerated fumed silica slurry used in ILD CMP utilizing filtration techniques, and to determine if they could be rendered analytically and functionally equivalent to fresh slurries.