Anisotropic topological charge migration microscopy for high-sensitivity 25 nm scale defect detection

The continuous downscaling of semiconductor process nodes imposes increasingly stringent sensitivity requirements on wafer defect detection. Conventional optical methods are fundamentally limited by diffraction, a low signal-to-noise ratio (SNR), and imaging contrast, which collectively impede the efficient and non-destructive detection of nanoscale defects. To overcome these limitations, we propose a three-dimensional imaging method based on anisotropic topological charge migration (ATCM). This method utilizes visible ±1st-order vortex beams for illumination. Modulation of the incident beam by the sample induces topological charge migration, resulting in 0th-order and high-order orbital angular momentum (OAM) signals. Complementary aperture slits spatially filter out high-order OAM components, effectively isolating defect signals from the background. Coupled with active illumination dark-line modulation, the system achieves directional selectivity, enabling the enhancement or suppression of oriented structure signals. Experimentally, ATCM significantly suppresses periodic background signals, achieving high-contrast imaging of 25 nm break defects and bridge defects, and enabling the detection of 10 nm gold nanoparticles. The method also provides three-dimensional (3D) imaging, allowing for the accurate localization of defects. Furthermore, ATCM enables label-free bioimaging, achieving high-SNR visualization of cellular and subcellular structures in both tissue sections and single cells. This method establishes a high-sensitivity 3D detection tool for both semiconductor detection and life sciences, offering significant potential for non-destructive detection and dynamic observation at the nanoscale.