The scanning electron microscope (SEM) has many advantages for tasks for as metrology and defect review compared to other competitive technologies, but the level of performance required to meet the specifications proposed for the next generation of devices will raise some significant problems that must be overcome. These include theoretical limits on the spatial resolution, practical limits to performance set by the electron-optical characteristics of the SEM, and the dynamic response of the instrument to signal information. Unwanted artifacts of the electron-solid interaction such as charging and radiation damage must also be considered as potential restrictions to performance.
David C. Joy, David C. Joy,
"Some issues in SEM-based metrology", Proc. SPIE 3332, Metrology, Inspection, and Process Control for Microlithography XII, (8 June 1998); doi: 10.1117/12.308720; https://doi.org/10.1117/12.308720