| 摘要 |
PURPOSE:To remove the noise signal generated in a detection system caused by the induced radio waves generated from a sample by providing a means detecting only the noise component caused by the induced radio waves generated from the sample and a means subtracting the detected noise component from the secondary electron detection signal. CONSTITUTION:The induced radio waves mixed in a detector 4 are changed in response to the change of the pattern data fed to a sample 6, an electron beam 1 is first blanked every time the pattern data are changed, only the noise component caused by the induced radio waves is detected and stored in a memory 11. An electron beam 1 is then radiated, the signal containing the noise component caused by the logical information of the sample 6 and the induced radio waves is detected and stored in another memory 12, the difference between the memories 11 and 12 is calculated by an arithmetic unit 13, thus the signal of only the logical information is extracted. The noise caused by the induced radio waves from the sample 6 itself can be thereby removed. |
