To overcome the limitations in the sensitivity and reliability of conventional wafer defect inspection techniques, a novel dual-channel optical inspection system is proposed by combining dark-field scattering with diffraction phase microscopy. Such an integrated system simultaneously acquires dark-field intensity and phase gradient signals arising from wafer defects, enabling comprehensive defect characterization at identical wafer locations while maintaining high sensitivity and high efficiency. Experimental validation using polystyrene particles demonstrates that the system achieves a limit of detection of 60 nm, improves the detecting sensitivity compared to single dark field scattering systems, and maintains the lateral/vertical limit of detection for small-scale defects. These results confirm its potential to meet the high-sensitivity and high-reliability requirements of unpatterned wafer defect inspection for advanced semiconductor manufacturing.
Zhang et al. (Sun,) studied this question.