Scanning electron microscope and scanning transmission electron microscope

A scanning transmission electron microscope comprising:

• a spherical aberration corrector for correcting a spherical aberration of an objective lens;
• a secondary electron detector;
• an aperture that determines an electron beam illumination angle;
• and
• a focusing unit,
• wherein a plurality of two-dimensional magnified scanning images of a specimen obtained by the secondary electron detector and having an atomic resolution is recorded, and a structure of a specimen uppermost surface and a structure inside the specimen are both simultaneously observed by changing a focal depth by varying the size of the aperture.

A scanning transmission electron microscope comprising:

• a spherical aberration corrector for correcting a spherical aberration of an objective lens;
• a secondary electron detector;
• a condenser lens that determines an electron beam illumination angle;
• and
• a focusing unit,
• wherein a plurality of two-dimensional magnified scanning images of a specimen obtained by the secondary electron detector and having an atomic resolution is recorded, a structure of a specimen uppermost surface and a structure inside the specimen can be both simultaneously observed by changing a focal depth by changing an excitation current for the condenser lens, the depth of the structure existing inside the specimen is measured by defocusing an electron beam with which the specimen is irradiated, and an optimum focal depth is determined.