Method of Automatic Defect Classification

A method of automatic defect classification (ADC) includes detecting defective parts from a substrate wherein at least one unit process is performed; and classifying defect types of the respective defective parts, wherein the classifying includes obtaining a scanning electron microscope (SEM) image of each of the defective parts; registering information about the substrate in a graphic data system (GDS) image corresponding to each SEM image; defining a plurality of defects of interest (DOIs) categorizing defects of the respective defective parts; defining a DOI rule that is a criterion for determining which defects of the respective defective parts correspond to which DOI from among the DOIs; and analyzing the image to classify which defects of the respective defective parts correspond to which DOI from among the DOIs according to the DOI rule.