Patent ID: 7426023

Claim:
A defect detecting apparatus comprising: a laser beam illumination optical system including: a laser source for emitting a laser beam having a Gauss distribution in its illumination intensity, a beam shape optical system for shaping said laser beam emitted from said laser source to be a laser beam having a flat distribution in its illumination intensity, an optical path switching unit for switching an optical path of said distribution-flattened laser beam between a first optical path and a second optical path, a high angle illuminator for illuminating said distribution-flattened laser beam switched to the first optical path by the optical path switching unit onto a substrate to be inspected, and a low angle illuminator for illuminating said distribution-flattened laser beam switched to the second optical path by the optical path switching unit onto the substrate to be inspected; a detection optical system that focuses and receives scattered light from said substrate on which said laser beam has been irradiated by said high angle illuminator and said low angle illuminator of said laser beam illumination optical system and that converts said received scattered light into a signal; and a signal processor for detecting defects on said substrate and classifying the detected defects on the basis of said signal converted by said detection optical system from scattered light received by said high angle illuminator and said low angle illuminator.