| 摘要 |
PROBLEM TO BE SOLVED: To provide a scanning electron microscope which realizes highly precise focus adjustment even under an observation condition with a great depth of focus.SOLUTION: A plurality of aperture holes of different diameters are formed on an aperture plate that eliminates an unnecessary area of a primary electron beam, and the aperture holes are switched to control an aperture angle of the primary electron beam that passes through the aperture holes without changing lens conditions of a converging lens and an objective lens. A condition is set to determine a resolution to be high and a depth of focus to be small. In this manner, focus adjustment precision is improved. |
