Patent ID: 7457455

Claim:
A pattern defect inspection apparatus for detecting defects by comparing a detection image obtainable through scanning, by an image sensor, patterns having an identical shape and being continuously laid out on an object to be tested at equal intervals in row and column directions with a reference image obtained by scanning patterns of the identical shape neighboring in the row and column directions thereof, said apparatus comprising: statistical computation means for calculating a quadratic curved plane which is adaptable to two-dimensional distribution of image intensity on each of image pixels of identical shape patterns lying next to the detection image including four nearest chips on up-and-down and right-and-leftsides with the detection image being intermediately situated according to the image intensity on image pixels; and means for detecting a defect by comparing image intensity of an image pixel of the detection image at a (x,y)—coordinate to another image intensity at another (x,y)—coordinate on the quadratic curved plane thus calculated.