Sensitivity Enhancement by Enabling Design-Based Inspection for DRAM

With shrinking design rules, detecting tiny defects of interest (DOI) is becoming more challenging for wafer inspection tools. Using design-based care areas for inspection systems to characterize DOI has been well established in recent years. KLA’s 293x broadband plasma (BBP) optical patterned wafer inspection system uses a high intensity laser pumped plasma illumination source, which enables selectable wavelength bands, and is also optimized for a design-based care area methodology to inspect critical patterns with higher sensitivity and to reduce nuisance rates in noisy regions. In this study, by enabling a design-based care area, the CAB (care area border) size will be further reduced to 0.05 ~ 0.1µm to scan more of the critical area. In a WCMP layer, unique microscratch DOI were successfully detected in the SA (sense amplifier) region, and 8.6x higher contact missing defects were captured in the target region compared to the legacy care area methodology.