Error Calibration Method Based on Perspective Mapping for Wafer Automatic Optical Inspection System

In the manufacturing process of the wafer, the positioning accuracy of the wafer automatic optical inspection (AOI) system affects the detection of die surface defect directly. Most existing error compensation methods generally analyze specific error or main sources of error and can improve the positioning accuracy in most of the applications. However, to fulfill the requirement of higher positioning accuracy of the wafer AOI system, in this article, we propose an error calibration method based on perspective mapping (ECM-PM), which only requires to focus on the total error of the system, regardless of the multiple error sources of the system. First, the error cause of the wafer AOI system is analyzed and the total error of the system is measured using the designed high-precision glass checkerboard calibration board. Then, the mapping model between motor coordinate system and checkerboard coordinate system is established. In addition, the total error of the system is calibrated based on the perspective mapping principle. Finally, the experimental results show that the proposed method obviously decreased the total error of the system and it is robust to the parameter of different recipe motor coordinates.