three dimensional SEM

The three dimensional SEM (3D-SEM) is a SEM aimed to measure the height of the unevenness of a specimen.
Since the SEM has a large focal depth, the entire topography of the specimen can be observed without image blurring. However, the height of the unevenness cannot be measured from one SEM image. The height of the unevenness can be measured by performing addition / subtraction calculations of the output signals from the pair detectors, which are (normally two pairs or four detectors) are placed rotational-symmetrically with respect to the specimen and beneath the electron probe. The 3D-SEM allows for quantification of the height, creation of the map of an arbitrary cross section, creation of a bird’s eye view of the specimen, and a statistical processing of the surface roughness of the specimen.