A pattern inspection apparatus includes a pulse laser light source sequentially
generating pulse laser light, an illumination optics applying the pulse laser light
onto a mask substrate, an imaging optics collecting light from the mask substrate
to form an image thereof, an area sensor sensing the image of the mask substrate
obtained by the optics in a rectangular area unit, a comparator comparing image
data acquired by the area sensor with previously prepared reference data to detect
a defect of a pattern, a stage driving apparatus two-dimensionally scanning a stage
having the mask substrate placed thereon, and a stage position detector detecting
a position of the stage. With the above configuration, it is possible to efficiently
inspect the surface of the mask substrate by adequately setting the moving speed
of the mask substrate and the sensing timing of the sensing apparatus.
