Pattern inspection method using charged particle beam

A pattern inspection method, comprising:

• scanning a plurality of patterns on a substrate with N charged particle beams and detecting secondary electrons respectively generated from each of the plurality of patterns to acquire N SEM images used to determine the presence of a defect in the pattern and concurrently;
• determining a related gray level value for each of the acquired N SEM images;
• selecting M gray levels from the distributions of the N gray levels for each of the acquired N SEM images;
• comparing the related gray level value of each of the M gray levels;
• determining which related gray level values, from among the M related gray level values, have a similar gray level value within a preset range of deviation of the gray level value, and determining which, if any of the related gray level values from among the M related gray level values have a value outside of a preset range of deviation from the other of the M gray level values;
• and
• stopping use of any charged particle beam corresponding to the gray level value, from among the M gray level values, having a value outside of a preset range of deviation from the other of the M gray level values.

A pattern inspection method, comprising:

• scanning a plurality of patterns on a substrate with N charged particle beams and detecting secondary electrons respectively generated from each of the plurality of patterns to acquire N SEM images useful for determining the presence of a defect in the pattern, and concurrently;
• selecting M images from the N SEM images;
• comparing a property of an N SEM image with the remaining N−1 SEM images;
• and
• determining whether the property of the selected N SEM image is different from that same property in the remaining N−1 SEM images by more than a preset threshold amount;
• and
• if the property of the selected N SEM image is different from that same property in the remaining N−1 SEM images by more than the preset threshold amount, stopping use of the charged particle beam corresponding to the SEM image having the property which is different from that same property in the remaining N−1 SEM images by more than the preset threshold amount.