| 摘要 |
PURPOSE:To discriminate the defect of the pattern by providing a detector for reflected beams from a normal section besides a detector for reflection diffraction beams from a defect section and discriminating a signal from a true defect section from an output signal. CONSTITUTION:The detectors 19a-19h are disposed in the directions of nX45 deg., and a diffraction signal from a normal pattern by beam irradiation is added 20 and amplified 21 and a signal Sn is obtained, and the detectors 8a-8e for diffraction beams from the defect section are set up in the directions of (2n+1)X 22.5 deg. and added 9 and amplified 10, and a signal Sd is formed. A signal 22 from the normal pattern is formed response to a signal 15, 23 in response to a defect signal 13', 24 in response to a defect signal 14 and 25 in response to a signal 16 from an isolated pattern respectively because diffraction beams mix in the mutual detectors. When a level is adjusted and Sd-Sn is obtained, only the defect signals remain as signals 23', 24', and false defect signals are all removed, thus extracting only true defects. |
