2025-2-24

Advanced pattern contour extraction function for see-through BSE images of high voltage SEM

• Event: PIE Advanced Lithography + Patterning 2025
• Masahiro Oya, Yosuke Okamoto, Shinichi Nakazawa, Kotaro Maruyama, Yuichiro Yamazaki, Shinji Murakami, Yoshihiro Midoh, and Noriyuki Miura
  
  Proc. SPIE 13426, Metrology, Inspection, and Process Control XXXIX, 1342626 (24 Feb. 2025);
  https://doi.org/10.1117/12.3050236

ABSTRACT

As semiconductor device dimensions shrink and multilayer structures become increasingly complex, direct overlay measurement on actual device patterns has become essential. We developed a high-voltage SEM (HV-SEM) based die-to-database (D2DB) overlay metrology method for multilayer structures. To accurately extract lower-layer contours from low-contrast see-through BSE images, we utilized an Active Contour Model with deep learning and trained the model using synthetic SEM datasets generated from layout data with realistic process-induced variations. Evaluation on imec BEOL wafers demonstrated accurate overlay measurements across multiple stacked layers. This paper describes the proposed methodology, validation results, and advantages of SEM-based see-through overlay metrology.

Key words: High voltage, EBI, SEM, D2DB, CD, EPE, Overlay, CVNet