Retainer Ring Defect Imaging During Wafer Polishing Rotation

The patent implements preliminary inspection of the retainer ring surface using an illumination device and camera device before the wafer polishing process. The camera captures images of the retainer ring inner surface, and the control unit analyzes these images to detect defects such as scratches or contamination. This preliminary detection action prevents defective retainer rings from causing wafer damage during actual polishing operations.

The patent introduces an intermediary imaging system consisting of a camera device and illumination device that mediates between the retainer ring and the control unit. The camera captures visual information about the retainer ring surface, and the illumination device enhances the visibility of potential defects. This intermediary system enables precise defect detection without requiring complex direct measurement mechanisms, maintaining system simplicity while achieving high detection precision.

The patent extracts the camera lens from the direct polishing environment by positioning it to capture images of the retainer ring inner surface from a distance. The illumination device provides sufficient lighting to enable clear imaging without requiring the camera to be in direct contact with the polishing area. This extraction approach maintains defect detection capability while preventing polishing debris from contaminating the camera lens.