Patent ID: 8755041

Claim:
A defect inspection method, comprising the steps of: acquiring, by using a plurality of detection optical systems, images of a sample, whose surface is formed with patterns, by sequentially shooting inspection regions including a pattern; correcting, as pre-processing, the images taken by the sequential shooting; generating inspection images and reference images sequentially from the corrected images; extracting defect candidates on the sample, by using a set or sets of an inspection image and a reference image, wherein the defect candidate extracting step comprises the sub-steps of: calculating a correction value for positioning the inspection image and the reference image of the same set; positioning the inspection image and the reference image with respect to each other on the basis of the calculated correction value; and extracting defect candidates by comparing the positioned inspection image and reference image, by using plurality of computing devices in such a manner that pieces of processing are performed in parallel by the plurality of computing devices, the plurality of computation processing devices and a parent computing device being connected to each other by a bidirectional data communication bus; calculating correction values for positioning the inspection image and the reference image of the same set for the plurality of respective detection optical systems on the basis of images acquired for the plurality of respective detection optical systems by processing, in parallel, with the plurality of computing devices, images of the same position on the sample acquired by the plurality of detection optical systems; positioning the inspection image and the reference image with respect to each other for the plurality of respective detection optical systems on the basis of the calculated correction values; calculating feature quantities of pairs of corresponding pixels of the positioned inspection image and reference image for the plurality of respective detection optical systems; forming a feature space by unifying sets of feature quantities calculated for the plurality of respective detection optical systems; finding pixels whose feature quantities are excessively deviated from a distribution in the feature space; and extracting, as defect candidates, the pixels whose feature quantities are excessively deviated from the distribution; and determining defects from the extracted defect candidates.