INSPECTING DEVICE FOR DEFECT OF PATTERN

PURPOSE:To extract a defect signal without being disturbed by a false defect signal by removing a detecting signal based on the reflection diffraction beams from a circular pattern on a sample surface by self-decision. CONSTITUTION:Photodetectors 18a-18d are fitted in the directions of (2n+1)X 45 deg. and outputs are synthesized 20 and amplified and a signal Sn(45) is formed, photodetectors 19a-19d are fitted in directions of 2nX45 deg. and outputs are added 22 and amplified 23 and a signal Sn(90) is formed, and a signal from normal pattern is obtained. Detectors 8a-8e for the diffraction beams of a defect section are fitted in the directions of (2n+1)X22.5 deg. and outputs are added 9 and amplified 10 and a signal Sd is formed. A diffraction signal 16' from the crystal grains 13 of the circular patterns and a defect signal 15'' from patterns 12 are made contain in the signal Sn(45), but the signal 15'' is smaller than a signal 15' in Sd in the patterns normally used. When a level is adjusted properly and a signal Sd-Sn(45) is obtained, only a signal 15''' corresponding to a defect remains, and only a desired defect signal can be drawn correctly from the circular patterns similar to the defect.