Patent ID: 10444623

Abstract:
Methods and a system for scanning scattering contrast inspection for the identification of defects in an actual pattern block on a sample as compared to a desired pattern block. Most of the information in the reciprocal space (spatial frequency domain) is omitted in order to increase the throughput. That information in the reciprocal space is captured which gives the highest defect information, namely contrast signal between the defective and defect-free structure. Deviations from the expected diffraction pattern allow rapid identification of defects on the actual pattern. The first method learns the correct reconstructed diffraction image by comparing the repetitive pattern blocks. The second method focuses on the appearance of predictable defects in the spatial frequency domain of the reconstructed diffraction image thereby defining regions of interest where the defects materialize. Only the regions of interest are considered and compared to the reconstruction diffraction image of a defect-free pattern block.