Patent ID: 8399832

Claim:
A scanning electron microscope for measuring a dimension of a pattern on a specimen based on electrons emitted from the specimen, the scanning electron microscope comprising: a processor for calibrating a measured dimension value with a calibration specimen, wherein said processor is configured to perform implemented steps of: forming an image based on a detected signal emitted from a field of view area, the image including a plurality of calibration pattern fields and positional alignment patterns on the calibration specimen, the calibration pattern fields each having the same pattern shape, and the positional alignment patterns having a plurality of patterns corresponding to each of the calibration pattern fields at different positions on the image, wherein shape or direction of the positional alignment patterns corresponding to the adjacent calibration pattern fields in the field of view area is different, wherein each one of the positional alignment patterns is used to distinguish a respective one of the calibration pattern fields, executing a pattern matching algorithm which detects each one of the positional alignment patterns for identifying a predetermined calibration pattern field which corresponds to a respective one of the detected positional alignment patterns by using a template image, and calibrating the measured dimension value with a calibration pattern of the predetermined calibration pattern field identified in the executing step.