Effect of pad groove width on slurry mean residence time and slurry utilization efficiency in CMP

This paper studies the effect of pad groove width on slurry mean residence time (MRT) in the pad–wafer interface as well as slurry utilization efficiency (η) during chemical mechanical planarization. Three concentrically grooved pads with different groove widths were tested at different polishing pressures to experimentally determine the corresponding MRT using the residence time distribution (RTD) technique. Results showed that MRT and η increased significantly when the groove width increased from 300 to 600 μm. On the other hand, when the groove width increased further to 900 μm, MRT continued to increase while η remained constant. Results also indicated that MRT was reduced at a higher polishing pressure while η did not change significantly with pressure for all three pads.