Effect of Viscosity on Ceria Abrasive Removal during the Buff Clean Process

In this study, the effect of viscosity on ceria abrasive removal during the buff clean process was investigated. First, a numerical simulation was performed to observe the shear stress on the wafer. The shear stress increased as the viscosity increased. These results imply that the viscosity increases the drag force acting on the abrasives, which can improve abrasive removal. Based on the results of the numerical simulation, the ceria abrasive removal was measured using inductively coupled plasma mass spectroscopy (ICP-MS). The ICP-MS results showed that the increased viscosity improved the cleaning efficiency of the ceria abrasive removal by 70%. In addition, a lowering of the water temperature also resulted in an increase in abrasive removal as the viscosity increased. These results can be used to improve ceria abrasive removal during the buff clean process.