US Patent 7248732 Pattern inspection method and inspection apparatus

A pattern inspection method and apparatus, wherein the target area is limited to a line part, having a simplified configuration and capable of detecting a killer defect as a defect candidate and considerably reducing the number of non-killer defects to be detected as defect candidates, have been disclosed. The present invention relates to a pattern inspection method and apparatus for judging non-matching parts to be defects by making a comparison between the same patterns having a line part in which a line extending in the longitudinal or transverse direction appears repetitively at a fixed pitch, wherein an average level of gray level data is calculated for each pixel columns in the direction in which the line extends, a type of the area of each pixel columns is classified into groups, a threshold value is determined for each area according to the statistical processing result of the type and the difference data of each pixel column, and the difference data is judged based on the threshold value.