Patent ID: 7551767

Claim:
A method of pattern inspection comprising: forming an optical image of a pattern formed on a plate to be inspected based on designed pattern data through imaging optics; generating detected pattern data using a detected pattern data generator after detecting the optical image; generating first reference pattern data from the designed pattern data, using a reference pattern data generator; comparing the detected pattern data with the first reference pattern data to detect a defect of the pattern formed on the plate using a first comparator; when there are a plurality of repeated pattern areas on the plate, reading an arrangement, a number, a dimension and a repeated pitch of the plurality of repeated pattern areas from the designed pattern data to store the inspection area as a basis of second reference pattern data using a computer; storing in a first memory pattern data obtained by detecting an inspection area, which is one of the plurality of repeated pattern areas, as the second reference pattern data; and comparing the detected pattern data with the second reference pattern data to detect the defect of the pattern formed on the plate using a second comparator.