On extensive pump handling of chemical-mechanical polishing slurries

The effects of extensive pump handling on chemical-mechanical polishing (CMP) slurries have been investigated in this study. A number of common CMP slurries were recirculated in bellows pump loops. Large particle counts (LPC) and particle size distributions (PSDs) were generated using commercially available instruments. The PSDs of oxide CMP slurries illustrate distinct, developing characteristics as a result of repeated shearing during handling. Unlike most silica oxide slurries, alumina- and ceria-based slurries do not seem to generate large particles due to pump handling over extended periods of time. Some of these slurries show a decrease in number of large particles or soft flakes in pump recirculation tests. The PSD and LPC data for an oxide slurry handling test in a vacuum-pressure-dispense-technology-based pump show generation of fewer large particles as compared to a bellows pump. This study also demonstrates that insignificant progressive settling of abrasive particles takes place inside the pump or in the pump loop during handling of quick-settling CMP slurries.