METHOD FOR INSPECTING OVERLAY SHIFT DEFECT DURING SEMICONDUCTOR MANUFACTURING AND APPARATUS THEREOF

A method of inspecting for overlay shift defects during semiconductor manufacturing is disclosed. The method can include the steps of providing a charged particle microscopic image of a sample, identifying an inspection pattern period in the charged particle microscopic image, averaging the charged particle microscopic image by using the inspection pattern period to form an averaged inspection pattern period, estimating an average width from the averaged inspection pattern period, and comparing the average width with a predefined threshold value to determine the presence of an overlay shift defect.