Epi Defect Quantification via Massive Metrology SEM Measurement-Based Inspection

In this study, a comprehensive analysis of epitaxial (epi) defect detection and characterization in semiconductor wafers used in nanosheet logic devices is presented. The wafers, featuring layers of n-type epi and p-type epi, exhibited various defects due to the novel deposition process. These defects included missing epi, overgrown epi, and merged epi. Traditional defect review scanning electron microscope (SEM) tools, which compare defective sites to "good" sites, proved inadequate due to the high defect density across the wafer. Consequently, we employed a SEM tool capable of massive metrology, enabling the measurement of gray levels, areas, and distances between epi sites. This approach provided detailed defect maps, quantifying the extent and distribution of missing, overgrown, and merged epi defects. Our findings demonstrate that the massive metrology SEM tool offers superior accuracy in process characterization for wafers with rampant unstable epi growth compared to conventional SEM defect review methods. This research is significant as it enhances our understanding of epi defect trends and supports the development of more reliable semiconductor manufacturing processes, potentially leading to higher yield and performance in advanced logic devices.