Patent ID: 6539106
Filing Date: 2003-03-25
Classification: G01R,G06K,G06T,H01J

Abstract:
A method of inspecting a patterned substrate, comprising:preparing a reference image and a test image of at least a portion of the patterned substrate; extracting features from the reference image and extracting features from the test image; matching features of the reference image and features of the test image; and comparing features of the reference image and of the test image to identify defects; wherein comparing features of the reference image and of the test image to identify defects comprises: computing feature properties in the reference image; computing feature properties in the test image; and comparing the computed feature properties in the test image with the computed feature properties in the reference image; wherein the computed feature properties comprise: area, size, center of gravity, average intensity, sum of intensity, and standard deviation of intensity; wherein comparing the computed feature properties comprises: calculating feature properties comparison statistics that include one or more of differences, ratios, greater-than or less-than functions, means, standard deviations, linear regressions, and adaptive thresholds; and determining whether the feature properties comparison statistics meet predetermined defect criteria.