SEMs (scanning electron microscopes) as well as optical microscopes are widely used for failure analyses.
With SEMs, the surface of the sample is observed by projecting electron beams on the sample and detecting
the secondary electron emitted from the sample, and the sample can be magnified from a few times to 100,000
times. As SEMs have a large focus depth and it is easy to obtain the observations of stereoscopic shapes, they
are used not only for failure analyses but also for acceptance inspections of materials or parts and for quality
control in the manufacturing process.