Optimizing the retaining ring structure can improve the quality of Chemical Mechanical Polishing (CMP). This study establishes a two-dimensional Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) model, while the model is validated by experiments. The results graphically demonstrate the influence of the retaining ring groove design on the motion of the slurry abrasive particles. The size of the retaining ring groove appears to have a threshold value, above which the abrasives start to have significant distribution in the wafer region. As the groove size continues to increase, the number of abrasives entering the ring increases abruptly and oscillates at specific nodes. The abrasive transfer rate increases with the number of grooves in the early stage but reaches a limit at a certain number of grooves. Meanwhile, the retaining ring position affects the transfer of the abrasives. This study provides a base for optimizing the design of retaining rings.

Understanding the mechanism of stress concentration effects on the surface of semiconductor substrate materials—silicon wafers—in Double-Sided Polishing (DSP) is particularly important for improving polishing quality. In this study, a two-dimensional finite element model is established to study the effect of contact state and stress concentration during polishing on edge roll-off (ERO) and polishing rate uniformity. The variation in this contact state is influenced by changes in wafer thickness and the gap between it and the carrier. The model is validated by experiments and helps to further analyze and interpret the experimental results, identifying six stages of contact states during the polishing process. The research indicates that the phenomenon of stress concentration at the edge of a wafer is caused by the pads creating a large amount of compression at the edge of the wafer. Additionally, there appears to be a threshold value during the polishing process, below which the stress concentration on the wafer changes, thereby altering the magnitude of edge roll-off and, ultimately, affecting overall flatness. This study provides a basis for optimizing the process design.

The surface quality of wafers processed by double-sided polishing (DSP) is significantly influenced by pad morphology. However, quantitative analysis remains challenging due to the complexity of dynamic contact conditions and the coupled effects of pressure and trajectory. To address material removal non-uniformity on wafer surfaces during DSP, this study focuses on the pressure–trajectory coupling mechanism and develops a material removal model incorporating pad topography effects. First, a kinematic model is established to derive the relative velocity of any point on the wafer. Secondly, a 3D elastic contact simulation model is constructed based on a linear elastic small-deformation model to obtain spatial pressure distribution under different pad morphologies. The full-cycle transient process is obtained by averaging typical steady-state conditions. A material removal calculation method is proposed by integrating time-dependent relative velocity and dynamic pressure within a modified Preston framework, and the model is validated against experimental results reported in the literature. Simulations and reported experiments demonstrate that pads with varying radial topographies generate differentiated pressure distribution. The results show that wafer radial within-wafer non-uniformity (WIWNU) can be effectively reduced to 1.002 by adjusting pad shape. This study extends the applicability of material removal rate models and provides a predictive framework for precision control in DSP wafer planarization.

Wafer surface quality processed by double-sided polishing (DSP) is significantly influenced by pad morphology. However, quantitative analysis remains challenging due to the complexity of dynamic contact conditions. To address material removal non-uniformity on wafer surfaces during DSP, this study focuses on the pressure-trajectory coupling mechanism and proposes a wafer surface optimization method based on controlled pad topography. First, a kinematic model is established to derive the relative velocity of any point on the wafer. Secondly, a 3D elastic contact simulation model is constructed based on linear-elastic small deformation model. The full-cycle transient process is obtained by averaging typical steady state conditions. A material removal calculation method is proposed by integrating relative velocity and dynamic pressure under different pad morphology over time, and the model accuracy is confirmed by Experimental validation. Simulations and experiments demonstrate that pads with varying radial topographies generate differentiated pressure distribution. The results show that wafer radical Within-Wafer Non-Uniformity(WIWNU) can be effectively reduced to 1.002 by adjusting pad shape. This study extends the applicability of material removal rate models and provides theoretical support for precision control in DSP wafer planarization.