Abstract
Scanning electron microscopes (SEM) are used extensively in research and advanced manufacturing for materials characterization, metrology and process control. Unfortunately, noise can limit the specimen-specific detail and the information that can be acquired in any SEM micrograph, or measurement made from those data. The majority of SEM measurements are done at low primary electron beam currents and fast imaging mode resulting in rather noisy signals - often too noisy. The amount and the type of the noise and the steps taken to deal with it are critical to the quality and amount of the information gathered. This fifth presentation, in this series of SEM dimensional metrology tutorial papers, discusses some of the various causes of measurement uncertainty in scanned particle beam instruments specifically dealing with signal-to-noise (SNR) and its contribution to measurement imprecision.