Patent ID: 7394070

Claim:
An apparatus for inspecting patterns, comprising: an electron source for generating an electron beam; focusing means for focusing the electron beam and irradiating the electron beam onto a specimen with one of the patterns formed thereon; a detector for detecting electrons generated from a surface of the specimen with the electron beam irradiated thereon; imaging means for forming an electron beam image of said one of the patterns based on a signal detected by the detector; determining means for determining a charge state of the specimen which allows the specimen to be inspected stably; potential adjusting means for changing at least one of a potential of the specimen and a potential of an electrode provided on a side of the electron source with respect to the specimen, to maintain the determined charge state of the specimen; and image evaluation value computation means for obtaining the electron beam image formed by the imaging means at each of a plurality of potentials adjusted by the potential adjusting means and determining an image evaluation value of the electron beam image.