Patent ID: 6944325

Claim:
A method for inspecting foreign matters in or on repeated micro-miniature patterns formed upon a surface of an object to be inspected, comprising following steps: obtaining an object image by picking up the image of the micro-miniature pattern, under a bright field illumination, at a coordinate position on the surface of said object to be inspected, which is designated previously; obtaining a reference image by picking up the image of the micro-miniature pattern, under a bright field illumination, at an another coordinate position on the surface of said object to be inspected, which is different from but corresponding to said coordinate position mentioned in the above step; obtaining at least one of (a) a difference image between said object image and said reference image and (b) a summation image of said object image and said reference image; and deciding a presence of a foreign matter at the coordinate position on said object to be inspected, which is previously designated, on a basis of at least one of (a) a difference between a distance between separate images of the foreign matter adjacent to each other and a width of said repeated micro-miniature patterns on the difference image, (b) the summation image being made on the micro-miniature pattern and the foreign matter to be compared to a predetermined threshold, and (c) colors of said different images adjacent to each other of the foreign matter.