Communication - Synergistic effect of mixed particle size on W CMP process: Optimization using experimental design

We have investigated the synergistic effect with mixing of three different-sized SiO₂ abrasives (30 nm-SiO₂, 70 nm-SiO₂ and 200 nm-SiO₂) and the corresponding W chemical mechanical planarization (CMP) performances. W removal rate significantly increased when the different-sized SiO₂ abrasives were mixed, which is attributed to the increase in the total contact area between the abrasives and the W film. Based on the statistical model, we obtained the optimal mixing ratio (30 nm, 70 nm, 200 nm) = (0.49, 0.23, 0.28) for the highest W removal rate. These results, investigated in this study, show that the removal rate of W film can be improved via simple mixing process.