Ben Tsai on overlay measurement
From Ben Tsai: Inspection and Metrology to Support the Quest for Perfection · · SPIETV
“Overlay measurement at sub-10 nanometer nodes faces significant challenges due to process variations, wafer shape differences, and non-uniformities across the wafer. Using advanced optical overlay techniques with multisite correction algorithms can significantly improve overlay accuracy and yield.”
On , Ben Tsai, Chief Technology Officer & Executive Vice President of Corporate Alliances at KLA Corp, spoke about overlay measurement during Ben Tsai: Inspection and Metrology to Support the Quest for Perfection on SPIETV.
About Ben Tsai
In a 2017 plenary talk at SPIE Advanced Lithography, Ben Tsai discussed the role of inspection and metrology in supporting sub-10nm lithography nodes. He stated that inspection methodologies are essential throughout semiconductor manufacturing to identify defects early, particularly as complexity increases with more layers and smaller features. Tsai described challenges in optical overlay measurement at these nodes, including the need for high precision on the order of 2 nanometers, and said this demands advancements in optics, brighter light sources, and polarization techniques. He also addressed issues in EUV lithography, noting that defectivity from resist and mask defects requires high-sensitivity inspection tools, and that the high photon energy of EUV introduces challenges such as shot noise. Tsai emphasized the importance of combining optical and electron beam inspection methods for defect detection and print check applications, citing optical tools' throughput and layer transparency alongside electron beam's high resolution for small systematic defects. He discussed the development of high-throughput, high-resolution tools such as multi-beam electron beam systems, and noted that overlay measurement faces challenges from process variations, wafer shape differences, and non-uniformities, which can be addressed with advanced optical overlay techniques and multisite correction algorithms. Tsai concluded that the key to successful pattern inspection at sub-10nm nodes is the optimal combination of different inspection and metrology technologies, stating, "I believe we can achieve Perfection by mastering the combination of imperfect pieces."