Defect classification with optimized purity
First Claim
1. A method for defect analysis, comprising:
- identifying, by a computer system, respective single-class classifiers for a plurality of defect classes, the plurality of defect classes characterized by respective ranges of inspection parameter values, each single-class classifier being configured for a respective class to identify defects belonging to the respective class based on the inspection parameter values, while identifying the defects not in the respective class as unknown defects;
identifying, by the computer system, a multi-class classifier configured to assign each defect to one of the plurality of the defect classes based on the inspection parameter values;
receiving, by the computer system inspection data with respect to a defect found in a sample; and
automatically applying both the single-class and multi-class classifiers to the inspection data, using the computer system, to assign the defect to one of the defect classes.
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Accused Products
Abstract
A method for defect analysis includes identifying single-class classifiers for a plurality of defect classes, the plurality of defect classes characterized by respective ranges of inspection parameter values. Each single-class classifier is configured for a respective class to identify defects belonging to the respective class based on the inspection parameter values, while identifying the defects not in the respective class as unknown defects. A multi-class classifier is identified that is configured to assign each defect to one of the plurality of the defect classes based on the inspection parameter values. Inspection data is received, and both the single-class and multi-class classifiers are applied to the inspection data to assign the defect to one of the defect classes.
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Citations
46 Claims
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1. A method for defect analysis, comprising:
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identifying, by a computer system, respective single-class classifiers for a plurality of defect classes, the plurality of defect classes characterized by respective ranges of inspection parameter values, each single-class classifier being configured for a respective class to identify defects belonging to the respective class based on the inspection parameter values, while identifying the defects not in the respective class as unknown defects; identifying, by the computer system, a multi-class classifier configured to assign each defect to one of the plurality of the defect classes based on the inspection parameter values; receiving, by the computer system inspection data with respect to a defect found in a sample; and automatically applying both the single-class and multi-class classifiers to the inspection data, using the computer system, to assign the defect to one of the defect classes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for analyzing defects, comprising:
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defining, by a computer system, a plurality of defect classes; receiving, by the computer system, a training set comprising inspection data with respect to defects that have been classified as belonging to respective defect classes; training, by the computer system, a plurality of classifiers using the training set to define a respective range of inspection parameter values that characterizes each defect class and, using the parameter values, to classify each defect as belonging to a respective class with a respective level of confidence; adjusting, by the computer system, a confidence threshold for rejection of defect classifications having low levels of confidence to achieve a specified purity target in classification of the training set; and applying, by the computer system, the trained classifiers with the adjusted confidence threshold to further inspection data outside the training set, wherein the plurality of classifiers comprises; a multi-class classifier, having a first confidence threshold such that the defects classified by the multi-class classifier as falling below the first confidence threshold are identified as non-decidable defects; and at least one single-class classifier, having a second confidence threshold such that defects classified by the at least one single-class classifier as falling below the second confidence threshold are identified as unknown defects. - View Dependent Claims (13, 14, 15)
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16. Apparatus for defect analysis, comprising:
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a memory, configured to store respective ranges of inspection parameter values for a plurality of defect classes; and a processor, which is configured to receive inspection data with respect to a defect found in a sample, and to apply both single-class and multi-class classifiers to the inspection data, based on the inspection parameter values, to assign the defect to one of the defect classes, wherein each single-class classifier is configured for a respective class to identify defects belonging to the respective class, while identifying the defects not in the respective class as unknown defects, and the multi-class classifier is configured to assign each defect to one of the plurality of the defect classes. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. Apparatus for analyzing defects, comprising:
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a memory, which is configured to store information with respect to a plurality of defect classes; and a processor, which is configured to receive a training set comprising inspection data with respect to defects that have been classified as belonging to respective defect classes, to train a plurality of classifiers using the training set to define a respective range of inspection parameter values that characterizes each defect class and, using the parameter values, to classify each defect as belonging to a respective class with a respective level of confidence, to adjust a confidence threshold for rejection of defect classifications having low levels of confidence to achieve a specified purity target in classification of the training set, and to apply the trained classifiers with the adjusted confidence threshold to further inspection data outside the training set, wherein the plurality of classifiers comprises; a multi-class classifier, having a first confidence threshold such that the defects classified by the multi-class classifier as falling below the first confidence threshold are identified as non-decidable defects; and at least one single-class classifier, having a second confidence threshold such that defects classified by the at least one single-class classifier as falling below the second confidence threshold are identified as unknown defects. - View Dependent Claims (28, 29, 30)
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31. A computer readable storage medium including instructions that, when executed by a processing device, cause the processing device to implement a method for defect analysis, the method comprising:
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identifying, by a computer system, respective single-class classifiers for a plurality of defect classes, the plurality of defect classes characterized by respective ranges of inspection parameter values, each single-class classifier being configured for a respective class to identify defects belonging to the respective class based on the inspection parameter values, while identifying the defects not in the respective class as unknown defects; identifying, by the computer system, a multi-class classifier configured to assign each defect to one of the plurality of the defect classes based on the inspection parameter values; receiving, by the computer system inspection data with respect to a defect found in a sample; and automatically applying both the single-class and multi-class classifiers to the inspection data, using the computer system, to assign the defect to one of the defect classes. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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42. A computer readable storage medium including instructions that, when executed by a processing device, cause the processing device to implement a method for defect analysis, the method comprising:
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defining, by a computer system, a plurality of defect classes; receiving, by the computer system, a training set comprising inspection data with respect to defects that have been classified as belonging to respective defect classes; training, by the computer system, one or more computerized classifiers using the training set to define a respective range of inspection parameter values that characterizes each defect class and, using the parameter values, to classify each defect as belonging to a respective class with a respective level of confidence; adjusting, by the computer system, a confidence threshold for rejection of defect classifications having low levels of confidence to achieve a specified purity target in classification of the training set; and applying, by the computer system, the trained classifiers with the adjusted confidence threshold to further inspection data outside the training set. - View Dependent Claims (43, 44, 45, 46)
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Specification