Optimized polarization in DUV scatterometry with global sensitivity analysis for accurate CD metrology of sub-micron microstructure structures
Journal
Measurement Science and Technology
Journal Volume
37
Journal Issue
3
Start Page
035003
ISSN
09570233
Date Issued
2026-01-23
Author(s)
Abstract
The advancement of chip-on-wafer-on-substrate technology has positioned three-dimensional (3D) packaging as a key enabler for next-generation artificial intelligence chips, thereby sustaining the trajectory of Moore’s Law. However, the continued scaling of critical dimensions (CDs), such as through-silicon vias (TSVs) and redistribution layers (RDLs), presents major challenges for CD metrology, primarily due to the difficulty of characterizing submicron hidden structures and limited light penetration. This study introduces an optimization framework based on global sensitivity analysis (GSA) to quantify the impact of CDs on optical responses and assess interaction effects on metrology performance. By combining GSA with rigorous electromagnetic simulations, the proposed approach enhances the extraction of CD information in optical CD (OCD) metrology. In particular, this work systematically analyzes key structural parameters in both submicron silicon trench structures and copper RDLs (Cu RDLs), providing a unified evaluation across two representative classes of semiconductor architectures. Key structural parameters, including depth, top CD, sidewall angle (SWA), and trench spacing, are systematically analyzed in submicron silicon structures. Furthermore, polarization optimization guided by sensitivity analysis is applied to maximize optical response sensitivity. Experimental validation shows that the GSA-optimized scatterometry setup achieves high measurement accuracy, maintaining a bias below 2% relative to focused ion beam/scanning electron microscope benchmarks. The findings demonstrate that CDs traditionally difficult to measure, such as depth and SWA of hidden submicron microstructures, can be accurately determined. Overall, the proposed methodology significantly enhances the accuracy and robustness of OCD metrology, providing valuable insights for advancing measurement strategies in 3D semiconductor packaging.
Subjects
deep ultraviolet (DUV)
global sensitivity analysis (GSA)
metrology
optical critical dimension (OCD)
scatterometry
through-silicon vias (TSVs)
Publisher
Institute of Physics
Type
journal article