Method and its apparatus for classifying defects
First Claim
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1. A method for classifying defects with a classification system including a computer and imaging apparatus, the method comprising steps of:
- obtaining with the imaging apparatus a defect image of a defect present in a sample;
calculating with the computer feature amounts of said defect from said defect image;
classifying said defect image with the computer into one of a plurality of classes based on said feature amounts and specified classification criteria to obtain a classification result of said defect image; and
displaying said classification result of said defect image,wherein said specified classification criteria are specified by the following steps;
selecting a set of classification criteria from a plurality of classification criteria displayed at the classification system, the set of classification criteria being associated with a predetermined classifying rule stored at the computer,modifying a class arrangement of the classification system based on input from a user by performing at least one of deleting, dividing or integrating the selected set of classification criteria with respect to the class arrangement, andadapting the classifying rule automatically in response to the modified class arrangement so as to avoid an empty area in a feature space of the classification system corresponding to the classifying rule.
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Abstract
A highly reliable defect automatic classifying method and apparatus capable of flexibly coping with a request for classifying a defect given by each user without having to collect lots of teach data items. A classifying class arrangement is defined by a user by combining classes supplied by the system itself or classes defined by the user and, further, a priori knowledge on the defect class is given by the user as a restriction so as to carry out restricted learning.
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Citations
14 Claims
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1. A method for classifying defects with a classification system including a computer and imaging apparatus, the method comprising steps of:
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obtaining with the imaging apparatus a defect image of a defect present in a sample; calculating with the computer feature amounts of said defect from said defect image; classifying said defect image with the computer into one of a plurality of classes based on said feature amounts and specified classification criteria to obtain a classification result of said defect image; and displaying said classification result of said defect image, wherein said specified classification criteria are specified by the following steps; selecting a set of classification criteria from a plurality of classification criteria displayed at the classification system, the set of classification criteria being associated with a predetermined classifying rule stored at the computer, modifying a class arrangement of the classification system based on input from a user by performing at least one of deleting, dividing or integrating the selected set of classification criteria with respect to the class arrangement, and adapting the classifying rule automatically in response to the modified class arrangement so as to avoid an empty area in a feature space of the classification system corresponding to the classifying rule. - View Dependent Claims (2, 3, 4, 5, 7, 8, 9, 10)
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6. A method of classifying defects with a classification system including a computer and imaging apparatus, comprising:
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establishing a plurality of user-defined defect categories by altering a class arrangement of the classification system in response to a user input, wherein the user input directs at least one predetermined category of the classification system to be deleted, divided or integrated with respect to other predetermined categories of the classification system; detecting a void in a feature space of the classification system based on the altered class arrangement; updating classification rules associated with the plurality of user-defined categories to eliminate the void; obtaining from a storage unit of the computer learning samples representative of defects occurring on a substrate; for each defect category in the plurality of user-defined defect categories; associating one or more of the learning samples with the defect category, restricting at least one feature amount of the defect category in accordance with a corresponding user input, and training a classifier with the learning samples such that feature amounts of the learning samples not within a feature space determined by restricting the at least one feature amount of the defect category are ignored by the classifier; obtaining with the imaging apparatus a defect image of a defect present on the substrate; calculating with the computer feature amounts of the defect image corresponding to a feature space defined by the plurality of defect categories; classifying with the computer the defect image into a target category based on the calculated feature amounts to obtain a classification result; and displaying at the classification system the classification result on a display screen, wherein the classification result indicates that the defect image corresponds to a region of the feature space defined by the learning samples and restrictions of the target category. - View Dependent Claims (11, 12, 13, 14)
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Specification