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.

The separation system is designed to separate and concentrate the aqueous glycol solution under a low-temperature heat source. The experiment found that the pore size of the capillary wick, the verticality of the evaporator, as well as the degree of vacuum and the inlet flow rate of the working fluid are important factors for the success of the experiment. At a vacuum of 10 kpa and a flow rate of less than 5 mL/min, the ethylene glycol aqueous solution was separated and concentrated at a temperature between 90 and 105℃, and the ethylene glycol content in the condensate was less, reducing the loss of ethylene glycol. The steam side vacuum capillary evaporation system proposed in this paper utilizes the difference of the surface force between the metal porous structure and the binary solution, thereby causing excess increase of the relative volatility of the two solution components, and strengthening the separation effect of the binary solution, meanwhile, the system can uses industrial waste heat as heat source, which has great potential to be a new kind of binary solution separation method.

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.

Enhancing the levelness of the wafer surface can be achieved by increasing the homogeneity of the radial motion speed of the wafer surface in relation to the polishing pad. In order to analyze the effects of the inner and outer pin ring rotational speeds, the equipment structure size, and the upper and lower polishing pad rotational speeds on the uniformity of the radial velocity distribution of the wafer surface with respect to the polishing pads, kinematics equations of the wafer surface relative to the polishing pads were constructed based on the kinematics of the planetary wheel system. The wafer's motion state with respect to the polishing pad is composed of two processes: rotation and revolution. Rotation is the reason for the uneven radial distribution of the wafer's surface speed; The surface velocity of the wafer is optimally dispersed with respect to the polishing pad when the polishing pad's rotational speed equals that of the planetary wheel; Increasing the polishing pad speed can result in a more equal speed distribution in the direction of the wafer radius with respect to the pad when the ratio of the outer pin ring speed N4 to the inner pin ring speed N3 is less than 1; The velocity homogeneity of the wafer in the radius direction can be enhanced by increasing the eccentricity of the wafer with regard to the planetary wheel and the distance between the center of the planetary wheel and the inner pin ring.