New Method for the Measurement of SEM Stage Vibrations

摘要

The National Institute of Standards and Technology (NIST) has implemented a high bandwidth laser interferometer measurement system in a specialized metrology microscope. The purpose of the system is the certification of SEM magnification calibration samples by moving the sample under a finely focused stationary electron beam in the metrology electron microscope. Using a laser interferometer with displacement measurements traceable to basic wavelength standards, the motion is measured while recording the secondary or backscattered electron output signal. The recent upgrade to the laser measurement system enables a measurement bandwidth of 300 kHz to be achieved in the sampling of the X-Y position of a test sample, along with measuring the intensity of the secondary electron beam output signal. This high bandwidth stage position measurement capability becomes a tool to measure the effects of environmental vibrations on SEM measurements. This paper outlines this ongoing research and presents the current results along with details of the measurement possibilities based on this new technique.