| 摘要 |
PURPOSE:To enable the distribution of secondary ions of within a specific energy range to be omnidirectionally detected with high efficiency and high resolution by synchronizing secondary electron detection signals for the second obstruction voltage with those for the first obstruction voltage stored in an image memory according to the position on the sample to obtain each difference between the signals for the same position thereby displaying an image. CONSTITUTION:When primary electrons 6 focused by an objective 8 are irradiated upon a sample 9, secondary electrons 14 are released from the sample 9 before being discharged through a lead-out electrode 10. Secondary electrons 14 with below a specific energy level are obstructed by a secondary-electron-obstructing electrode 12 and do not enter a secondary electron detector 15. The result obtained by scanning primary electrons 6 over the sample 9 and then sampling the signal produced by the secondary electron detector 15 by a sampler 17 through an amplifier 16, is stored in an image memory 19. Secondary electron detection signals obtained with a different secondary electron obstruction voltage are synchronized with the secondary electron detection signals stored in the image memory 19 according to the position on the sample to obtain each difference between the signals for the same position, thereby displaying an image. |
