Patent ID: 8207513

Claim:
A scanning electron microscope for obtaining an image of a scanned region of a specimen by a primary electron beam, comprising: an electron optical system including an electron gun for emitting the primary electron beam, an objective lens for converging the primary electron beam and generating a focal point on the specimen, and a deflector for scanning the primary electron beam on a scanning region of the specimen; a focus adjustment means for adjusting a focal position of the primary electron beam by controlling said objective lens; a stigmator for adjusting an astigmatic aberration of the primary electron beam; a memory means for storing a relation between either an astigmatism adjusting value used by said stigmator or a focus adjustment value used by said focus adjustment means, and either a deflection position or a deflection angle of the primary electron beam by said deflector; a controller for controlling said stigmator, said deflector and said focus adjustment means, wherein said controller controls said focus adjustment means so that the primary electron beam is focused on the specimen in accordance with said relation and in interlocked relation to the scanning position of the primary electron beam, or controls said stigmator so that the astigmatic aberration of the primary electron beam is corrected in accordance with said relation and in interlocked relation to the scanning position of the primary electron beam; and a focus correction electrode for adjusting the focal position of the primary electron beam; wherein said scanning region is divided into a plurality of areas, and adjustment values for adjusting said focal position to each of the areas or adjustment values for correcting said astigmatic aberration beam to each of the areas are stored in said memory means in correspondence with positions of said divided areas in the scanning region, and wherein the adjustment value to a divided area including a center of the scanning region is determined by using the focus adjustment means, while the adjustment values to the other divided areas of the scanning region are determined by using the focus correction electrode.