High-sensitivity, high-throughput inspection of nanoscale defects using a laser confocal positioning-assisted darkfield imaging system

Abstract

Nanoscale defect inspection of patterned wafers is critical for advanced semiconductor manufacturing. However, achieving both high sensitivity and efficiency remains a key challenge in defect inspection. This paper proposes a wide-range, non-destructive nanoscale defect inspection method using a laser confocal positioning-assisted darkfield imaging system. By analyzing and extracting the spatial and frequency domain information in optical images, an inspection framework is established to enhance defect features while suppressing noise, effectively optimizing the processing of optical scattering signals. Experimental results show that the signal-to-noise ratio is improved to approximately fivefold and the defect contrast is improved to approximately sevenfold, substantially boosting inspection sensitivity. Over a line scan range of 4 mm, typical defects of patterned wafers with a line width or diameter of 55 nm are accurately inspected and located using non-destructive visible light via optical far-field mode. The proposed method has the capability for high-throughput and high-sensitivity inspection of defects on patterned wafers, and can be extended to bare wafers, with broad application potential in semiconductor manufacturing and nanotechnology researches.