Numerical study of slurry replacement and distribution in chemical mechanical polishing using multi-zone analysis

Chemical mechanical polishing (CMP) is a critical process in semiconductor fabrication, where controlling slurry behavior at the pad-wafer interface is essential for achieving uniform material removal. This study investigates how variations in the relative rotational speed between the CMP pad and polishing head affect slurry transport characteristics, including replacement rate, coverage, and spatial uniformity. CFD simulations were performed, modeling the slurry as an incompressible Newtonian fluid, and the pad-wafer interface was divided into five concentric zones for zone-specific analysis. Increasing pad speed improved slurry replacement by up to 42.6% but reduced coverage by about 20%. This zone-based approach revealed localized nonuniformities not captured by global averages, emphasizing the need for spatially resolved evaluation. Complementing these quantitative results, qualitative flow analyses clarified how relative motion impacts slurry behavior, particularly highlighting nonuniformities in the outer interface zones. Our robust evaluation framework offers a practical basis for improving slurry dynamics in the CMP.