JPS6410155A - Optical surface inspecting method - Google Patents

Abstract

PURPOSE:To count abnormal positions in a specific area of a sample by counting the pulse signal of the scattered light of a light beam only when the inspection area is scanned by utilizing a difference among the intensity values of the scattered light inside, at the edge of, and outside the sample. CONSTITUTION:The intensity values of scattered light beams 8 and 22 of the light beam 6 scanned on the sample 5 and in an area outside the sample are different outside the sample, at the edge of the sample, and inside the sample, which is utilized to provide two decision levels to detect the border of the sample between the scanning direction of the light beam and a direction at right angles to it. Further, the fact that the scanning speed of the light beam, the period of the scanning, and the relative moving speed of the sample with the light beam are constant respectively is utilized to set the distance of the sample from the border, thereby determining the inspection area 34. Only when the light beam 6 is scanned in the inspection area 34, a gate 39 which counts 41 the pulse signal of the scattered light 8 from an abnormal position 7 is opened to inspect the abnormal position 7 in the inspection area by a simple procedure.