| 摘要 |
PURPOSE:To reduce the ratio of counting omission in detected pulse signals of secondary electrons of an electron microscope used for evaluation of semiconductor integrated circuit device. CONSTITUTION:The detected pulse signal detected by a secondary electron detector 3 is first transmitted to a discriminator 5. The discriminator 5 determines a threshold voltage and conducts the digital processing of the detected pulse signal. When the threshold voltage to the detected pulse signal is determined, the integrated type pulse wave height distribution showing the change of the digital pulse signal number obtained when the threshold voltage to the detection pulse signal is gradually changed is determined, and its peak value is taken as the threshold voltage. Thereafter, the number in the sampling period of the digital pulse signal outputted from the discriminator 5 is counted by a counter, and the data of the number is transmitted to an image memory 10. |
