Scanning electron microscope having magnification switching control

The scanning electron microscope comprising:

• a stage for mounting an object substrate;
• an electron gun for emitting electron beam;
• a converging lens for converging the electron beam emitted from the electron gun;
• scanning unit for two-dimensionally scanning a surface of the object substrate with the electron beam converged by the converging lens;
• an objective lens for focusing the electron beam converged by the converging lens in a spot-like shape on the surface of the object substrate;
• a detector for detecting an intensity of at least one of secondary electron or reflected electron or absorbed electron generated from the object substrate by scanning with the electron beam by the scanning unit and outputting an analog image signal;
• an A/D conversion unit for sampling the analog image signal detected by and outputted from the detector and converting the analog image signal into a digital image signal;
• a switching control unit for controlling to switch at least the scanning unit so that a digital image signal having a low magnification based on a wide image taking field of view and a digital image signal having a high magnification based on a narrow image taking field of view are provided to be switched from the A/D conversion unit;
• and
• a beam spot diameter control unit for controlling to switch a spot diameter of the electron beam at the surface of the object substrate in accordance with the magnification when the scanning unit is controlled so as to switch by the switching control unit.