| 摘要 |
PROBLEM TO BE SOLVED: To focus on the entire surface of a sample, without being affected by the inclining direction of the sample surface by adapting focus correction of an electron beam corresponding to the inclination angle of the sample surface to be made in two directions of X and Y. SOLUTION: The whole observation area of a sample can be focused corresponding to its inclination, by varying magnetic fields of an objective lens through varying a control voltage V of an objective control amplifier, according to inclination anglesθx,θy of an observed sample in X and Y directions in synchronization with the movement of a deflection coil. In contrast to normal automatic focusing functions performed at a point O in the center of the observation area, this automatic focusing function is performed at a point A shifted from the point O in the X-direction and an point B shifted in the Y-direction by controlling an electric visual-field moving coil, a processing/control circuit calculates the inclination anglesθx,θy in the X and Y directions from the differences from the point O in focal distances, and inclination corrections calculated are added to the control of the objective lens, and thereby the whole observation area can be focused corresponding to the inclined sample surface.
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