| 摘要 |
PURPOSE:To obtain an improved picture with an improved S/N ratio by installing a sample holding circuit, which retains the output of a detector by sampling the said output by means of sampling signals synchronized with a circuit driving a sample. CONSTITUTION:After an electron beam is irradiated on the LSI board 53 or the like by means of an electron-beam irradiating part 52 installed within a scanning electron microscope 51, secondary electrons generated at the electric potential of the board 53 are detected by a detector 54, and are sent into a sample holding circuit 56. Next, the sample holding circuit 56 is sampled by a sampling- signal generator 58, which produces sampling signals synchronized with a driving circuit 57 driving the board 53, and is displayed on a CRT60. As a result, since the signal which samples the secondary electron signal can be retained until the next sampling is carried out, the S/N ratio can be widely improved, and the quality of pictures can be easily enhanced. |
