Patent ID: 6909501

Claim:
A pattern inspection apparatus, comprising: a pulse laser light source which generates pulse laser light; an illumination optics which illuminates a to-be-inspected object with the pulse laser light from the pulse laser light source; an imaging optics which collects light from the to-be-inspected object illuminated by the illumination optics to form an image of the to-be-inspected object; an image sensing apparatus which senses the image of the to-be-inspected object obtained by the imaging optics in a rectangular area unit, the image sensing apparatus including one area sensor and fetching the image once for each pulse in synchronism with the pulse laser light; a comparator which compares image data acquired by the image sensing apparatus with previously prepared, reference data to detect a defect of a pattern; a stage driving apparatus which two-dimensionally scans a stage having the to-be-inspected object placed thereon; and a stage position detector which detects a position of the stage and outputs position data thereof, wherein the stage driving apparatus closely scans a surface of the to-be-inspected object by repeatedly making continuous movement at a speed of LxF/n in an x direction and stepwise movement of Ly in a y direction when an area on the to-be-inspected object which is fetched by one measurement by the area sensor is a rectangle of Lx (length)×Ly (length), a frequency of the pulse laser light is F, and n is a positive integer; and the comparator calculates average data by averaging n image information items obtained for respective coordinates on the to-be-inspected object corresponding to one pixel on the area sensor based on position data of the stage and image data obtained from the image sensing apparatus and compares the average data with the previously prepared reference data.