Slurry injection schemes based on flow field distribution during chemical mechanical polishing process

In chemical mechanical polishing (CMP), the injection position of the polishing slurry significantly affects the interfacial hydrodynamics, abrasive transport, removal efficiency, and overall planarization. This study systematically investigates the influence mechanism of the slurry injection position in the CMP process of 12-inch wafers via a multiphase flow–discrete phase coupling computational fluid dynamics (CFD) model combined with a user-defined function (UDF) to constrain abrasives. The results show that the injection position directly determines the distribution of slurry between the wafer and the polishing pad. At 45 mm from the pad center, the slurry effectively fills the gap, achieving the highest material removal rate (MRR). At 105 mm, the slurry is distributed most uniformly beneath the wafer, resulting in optimal planarization. However, at 165 mm, the slurry flow extends beyond the wafer center, causing abrasive agglomeration and localized overpolishing, which significantly decreases the surface uniformity. Dye visualization and CMP experiments with 12-inch copper wafers validate the accuracy of the model. The findings suggest that the slurry injection position should balance the material removal rate and planarity to optimize the slurry distribution system, providing a theoretical basis for future optimization efforts.