Optical pattern inspection system

Abstract

A pattern inspection apparatus comprises a sensor data input section for inputting a two-dimensional inspected pattern as image data (sensor data) having a multivalued (non-binary) density distribution, design data input section for inputting reference pattern data (reference data) corresponding to the inspected pattern, a compare section for making a comparison between the image data and the reference data to obtain the difference in density therebeween, a minimum compare section for performing spatial differentiation filtering on the distribution of density between the inspected pattern and the reference pattern in different directions and obtaining the minimum of the absolute values of the filtered outputs, and a first defect determining section for detecting a defect on the basis of the minimum obtained by the compare section. In place of the first defect determining section, a maximum/minimum compare section for obtaining the minimum and maximum of the absolute values of the filtered outputs and a second defect determining section for detecting a defect on the basis of the density difference, the minimum and the maximum may be provided.