Interaction effects of slurry chemistry on chemical mechanical planarization of electroplated copper

Recent studies have been conducted investigating the effects of slurry chemistry on the copper CMP process. Slurry pH and hydrogen peroxide concentration are two important variables that must be carefully formulated in order to achieve desired removal rates and uniformity. In applications such as through-wafer vertical interconnects, slurry chemistry effects must be thoroughly understood when copper plating thicknesses can measure up to 20 μm thick. The species of copper present on the surface of the wafer can be controlled through formulation of the slurry chemistry resulting in minimizing non-uniformity while aggressively removing copper. Using a design of experiments (DOE) approach, this study was performed, investigating the interaction between the two variables during CMP. Using statistical analysis techniques, a better understanding of the interaction behavior between the two variables and the effect on removal rate and uniformity is achieved.