In this study, a 3x-nm after development inspection (ADI) wafer with focus
exposure matrix (FEM) was inspected with both an advanced optical system and an
advanced EBI system, and the inspection results were carefully examined. We found that
EBI can capture much more defects than optical system and it also can provide more
information about within reticle shot defect distribution. It has high capture rate of certain
critical defects that are insensitive to optical system, such as nano-bridges.