Evaluation Technique of High Frequency Electron Beam Vibration in Scanning Electron Microscope

In this paper, we propose a technique to quantify the impact of electrical noise with frequencies above 100 kHz on the electron beam in order to improve the efficiency of noise neutralization in SEM (Scanning Electron Microscope). The proposed technique involves halting the electron beam scan at sample step edges, where the spatial variation in brightness becomes significant during SEM imaging, and converting electron beam vibration into brightness fluctuations for detection. Evaluation of the proposed electron beam vibration detection technique using an actual SEM revealed that the technique is capable of detecting electron beam vibration at frequencies exceeding 1 MHz. By applying this proposed technique to SEM, it has become possible to understand the effects of switching noise with frequencies above 100 kHz—noise that has been increasingly present within recent devices—on the electron beam, significantly enhancing the efficiency of identifying noise sources and implementing countermeasures.