| 摘要 |
PURPOSE:To prevent unevennesses generated in a picture by controlling the voltage applied to a secondary electron detector in a scanning electron microscope so as to suppress the voltage level variation caused by the scanning position depending on the output of the detector. CONSTITUTION:An electron beam 1 from the Z-axis direction is incident on a sample 2 and the X-Y plane is scanned two-dimensionally. In addition, a secondary electron 3 to be generated is guided to a scintillator 4, converted to light beam, amplified by a photomultiplier tube 8 and is displayed on a CRT10. Further, the output of the photomultiplier tube 8 passes through a low pass filter 15 and harmonic components are removed. The output is input to a differential amplifier 16 and compared with the input reference of a variable resistor 18 and then controls the voltage applied to the scientillator 4 through an inverse phase amplifier 21 and a drive circuit 19. As a result, the voltage level variation caused by the scanning position of an electron beam to the sample 2 can be compensated and the unevennesses generated in a secondary electron picture can be eliminated. |
