APPARATUS AND METHOD FOR INSPECTING PATTERN
First Claim
1. An apparatus for inspecting pattern on an object, comprising:
- a differential image generator for generating a differential image representing a difference between a grayscale inspection image representing pattern on an object and a grayscale reference image or a difference between two images obtained from said inspection image and said reference image, respectively, or a differential image obtained from an image representing said difference;
a defect candidate image generator for generating a defect candidate image representing an area which includes a defect candidate in said inspection image by comparing said inspection image with said reference image;
a differential image masking part for masking said differential image with said defect candidate image to obtain a masked differential image;
a feature value calculation part for obtaining an autocorrelation feature value from said masked differential image; and
a classifying part for performing a classification of said defect candidate on the basis of said autocorrelation feature value.
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Abstract
An operation part in a pattern inspection apparatus includes a defect candidate image generator for generating a binary defect candidate image representing a defect candidate area in an inspection image by comparing the inspection image with a reference image, in an inspection image masking part the inspection image is masked with the defect candidate image to obtain a masked inspection image. In a feature value calculation part, an autocorrelation feature value is obtained from the masked inspection image, and outputted to a classifying part. The classifying part comprises a classifier outputting a classification result on the basis of the autocorrelation feature value and a classifier construction part for constructing the classifier by learning. It is thereby possible to easily perform the high accurate classification of defect candidate using the autocorrelation feature value which is hard to characterize as compared with geometric feature value or feature value representing density.
40 Citations
14 Claims
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1. An apparatus for inspecting pattern on an object, comprising:
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a differential image generator for generating a differential image representing a difference between a grayscale inspection image representing pattern on an object and a grayscale reference image or a difference between two images obtained from said inspection image and said reference image, respectively, or a differential image obtained from an image representing said difference; a defect candidate image generator for generating a defect candidate image representing an area which includes a defect candidate in said inspection image by comparing said inspection image with said reference image; a differential image masking part for masking said differential image with said defect candidate image to obtain a masked differential image; a feature value calculation part for obtaining an autocorrelation feature value from said masked differential image; and a classifying part for performing a classification of said defect candidate on the basis of said autocorrelation feature value. - View Dependent Claims (2, 3, 4, 5)
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6-8. -8. (canceled)
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9. A method for inspecting pattern on an object, comprising the steps of:
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a) generating a differential image representing a difference between a grayscale inspection image representing pattern on an object and a grayscale reference image or a difference between two images obtained from said inspection image and said reference image, respectively, or a differential image obtained from an image representing said difference; b) generating a defect candidate image representing an area which includes a defect candidate in said inspection image by comparing said inspection image with said reference image; c) masking said differential image with said defect candidate image to obtain a masked differential image; d) obtaining an autocorrelation feature value from said masked differential image; and e) performing a classification of said defect candidate on the basis of said autocorrelation feature value. - View Dependent Claims (10, 11, 12, 13)
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14-16. -16. (canceled)
Specification