An approach to reducing the distortion caused by vibration in scanning electron microscope images

When images are obtained from a scanning electron microscope (SEM), several types of noise are frequently included. These noises have a great influence on the image of the specimen. In general, a rotary pump and a turbo pump are used to make the emitted electron beam pass the lens aperture and reach the specimen without any collision with impurities. At this time, the motors of these two pumps generate vibration on the equipment. This vibration is minimized by the vibration suppressor, which is external to the equipment. But, when the image is magnified 40,000 times, the distortion caused by the vibration can be seen in the image. In this paper, a frequency analysis was carried out on the vibration, and a method of minimizing the distortion using the phase-controlled signal was proposed. The improved image results show its validity.