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Scanning electron microscopes are metrology and inspection instruments that form images by scanning a focused electron beam across a sample and collecting emitted signals. Scanning electron microscopes are used when optical microscopy does not provide enough surface detail or material contrast for the inspection task. In semiconductor and microfabrication work, scanning electron microscopes are commonly used to examine patterned features, sidewall shape, defects, particles, and other small surface structures.

A field emission scanning electron microscope focuses electrons into a very fine probe and rasters that probe over the sample surface. Secondary electron and backscattered electron signals carry different kinds of contrast, so the instrument can emphasize topography, material contrast, or surface detail depending on the detector and operating conditions. Analytical attachments on machines of this class can add elemental and crystallographic information to the image-based inspection workflow.

In semiconductor and microfabrication flows, a scanning electron microscope is typically used after a structure has been created or modified and needs visual or dimensional verification. A scanning electron microscope commonly follows lithography, etch, deposition, cleaning, or sample preparation steps when engineers need close inspection of the resulting surface or feature shape. A scanning electron microscope can also be used during failure analysis and process development to compare physical results with intended pattern geometry.