System, method and computer program product for classifying defects

A method of obtaining a training set for a classifier, using a processor operatively connected to a memory, the method comprising:

• upon receiving in the memory object inspection results comprising data indicative of potential defects, each potential defect of the potential defects associated with a multiplicity of attribute values defining a location of the potential defect in an attribute space:
• sampling by the processor a first set of defects from the potential defects, wherein the defects within the first set are dispersed independently of a density of the potential defects in the attribute space;
• and
• obtaining by the processor a training defect sample set comprising the first set of defects and data or parameters representative of the density of the potential defects in the attribute space.

A non-transitory computer readable medium comprising instructions that, when executed by a computer, cause the computer to perform a method of examination of a semiconductor specimen, the method comprising:

• upon receiving in the memory object inspection results comprising data indicative of potential defects, each potential defect of the potential defects associated with a multiplicity of attribute values defining a location of the potential defect in an attribute space:
• sampling by a processor a first set of defects from the potential defects, wherein the defects within the first set are dispersed independently of a density of the potential defects in the attribute space;
• and
• obtaining by the processor a training defect sample set comprising the first set of defects and data or parameters representative of the density of the potential defects in the attribute space.