Patent ID: 9683946
Date: 2017-06-20
CPC Classifications: G01N

Claim:
1. A defect detecting method comprising the steps of: irradiating a sample with a light from a light source of an illumination optical system arranged such that said light is incident on a surface of the sample from an oblique direction; condensing scattered light generated from the sample irradiated with the light and incident on an objective lens to focus an image of the scattered light; acquiring said image by using a controller to adjust a position of said objective lens with respect to the sample such that the focused image of the scattered light is focused onto a detection face of an imaging element; extracting a defect on the sample by processing the acquired image using a signal processor configured to calculate position information of the extracted defect; and outputting the calculated position information of the defect to a display, wherein in focusing the image of the scattered light, the controller is configured to suppress an occurrence of a elongating phenomenon by the scattered light scattered to a region near to an outer edge portion of an aperture of the objective lens by focusing a light partially shielding a component of the scattered light transmitting the region near to the outer edge portion of the aperture of the objective lens in the scattered light generated at the surface of the sample by irradiating the light in the scattered light incident on the objective lens, and wherein the position information of the extracted defect is calculated by the signal processor based on a luminance gravity center of the defect extracted from the image acquired by taking the image of the scattered light suppressing the occurrence of the elongating phenomenon by the scattered light scattered to the region near to the outer edge portion of the aperture of the objective lens.