  In this article, a new scanning electron microscopy (SEM) image composition
technique is described, which can significantly reduce drift related image
corruptions. Drift-distortion commonly causes blur and distortions in the SEM
images. Such corruption ordinarily appears when conventional image-acquisition
methods, i.e. "slow scan" and "fast scan", are applied. The damage is often
very significant; it may render images unusable for metrology applications,
especially, where sub-nanometer accuracy is required. The described correction
technique works with a large number of quickly taken frames, which are properly
aligned and then composed into a single image. Such image contains much less
noise than the individual frames, whilst the blur and deformation is minimized.
This technique also provides useful information about changes of the sample
position in time, which may be applied to investigate the drift properties of
the instrument without a need of additional equipment.

Instrumentation and Detectors