| In response to the necessity for a high-precision automatic detection of multiple wafer defects in the manufacturing process of Micro-LED chips, a large-field-of-view polarized dual-channel automatic optical inspection system for wafer defects has been designed. The optical design of the system has been meticulously crafted to ensure optimal performance. It boasts a 20-fold magnification, a uniform illumination level of 91.6%, and an impressive maximum image-square field of view of 33 mm. The system""s MTF curve exhibits a close proximity to the diffraction limit at the Nyquist frequency of 31lp/mm, and its system resolution of 0.8 μm is in alignment with the object-square resolution specifications. A comparison with the conventional single-channel defect detection method reveals that the system captures the feature information of various defect types in real time. This is accomplished by employing a large-faceted array main inspection camera and a double-inspection polarimetric camera. The former possesses the advantages of a large field of view, high detection efficiency, and low leakage rate. The mean enhancement rates of information entropy, edge strength, standard deviation, and average gradient of the polarimetric image relative to the traditional gray-scale image are calculated to be 25.6%, 24.9%, 33%, and 173.3%, respectively. These enhancement rates meet the practical requirements of wafer defect detection. |
