METHOD FOR PATTERN DEFECT

摘要

The pattern defect detection method comprises the steps of detecting images at corresponding portions of two originally identical patterns and producing two image signals representing the images which are registered with each other. A second image signal of the two registered signals is shifted by a predetermined number of pixels with respect to a first image signal, thus providing shifted second image signals. Differences in brightness between the image signals as well as each of the shifted second image signals are calculated within intervals corresponing to pixels on one scanning line, thus providing a first group of difference image signals. Preset values are added to and subtracted from the first or second image signal to provided a sum image signal and a substraction image signal.