Semiconductor Metrology and Inspection

• ·Frequency-comb-enabled nanometrology for semiconductor and advanced manufacturing·

  This research thrust translates the extreme temporal precision of frequency combs into high-impact solutions for semiconductor manufacturing and advanced industrial inspection. We develop ultrafast time-of-flight (TOF) measurement techniques capable of sub-nanometer and even angstrom-scale resolution, enabling non-destructive metrology of complex semiconductor structures such as 3D integrated circuits, through-silicon vias (TSVs), and multilayered photonic devices.

  Our approach combines frequency-comb-based sensing with advanced signal processing and machine learning methods, enabling high-precision inspection of complex nanoscale structures that are increasingly difficult to characterize using conventional techniques. Beyond static measurements, we investigate the high-speed dynamics of nanostructures and develop massively parallel imaging approaches for multidimensional metrology. These technologies provide the high-throughput and high-precision sensing capabilities required for next-generation semiconductor fabrication and nano-manufacturing systems.

  
  Representative Publications [1] J. Bae et al, "Single-shot reflectometric monitoring of silicon melting in nanosecond laser annealing," Optics & Laser Technology 204, 116845 (2026) [2] Y. Na et al, "Frequency comb-based time-domain tracking of AFM cantilever dynamics from picometre-scale noise to micron-scale nonlinear motion," PhotoniX 6, 36 (2025) [3] H. Choi et al, "Backside illumination-enabled metrology and inspection inside 3D-ICs using frequency comb-based chromatic confocal and spectral interferometry," Light: Advanced Manufacturing 6, 74 (2025) [4] H. Kwak et al, "Semiconductor multilayer nano-metrology with machine learning," Nanomanufacturing and Metrology 6, 15 (2023) [5] Y. Na et al, "Massively parallel electro-optic sampling of space-encoded optical pulses for ultrafast multi-dimensional imaging," Light: Science & Applications 12, 44 (2023) [6] H. Kwak et al, "Non-destructive thickness characterisation of 3D multilayer semiconductor devices using optical spectral measurements and machine learning," Light: Advanced Manufacturing 2, 9-19 (2021) [7] Y. Na et al, "Ultrafast, sub-nanometre-precision and multifunctional time-of-flight detection," Nature Photonics 14, 356-360 (2020)