Contrast enhancement in the scanning electron microscope (SEM) is usually achieved by either of the two techniques of black level suppression, and differential imaging. This paper is mainly concerned with the latter method. Differential imaging of SEM images is commonly accomplished by either using a selective electronic filtering circuit (time sensitive) on the video signals, or the post processing of a collected digitized image (application of special kernel operatives). A technique is described that is capable of generating true in-situ SEM differential video signals of local sample features. Characteristics of this method are enhanced sample feature-boundary sensitivity, suppression of large background signals, and the ability to perform critical pattern alignments prior to feature measurements. Results are presented on the application of the technique to the general field of electron microscopy, as well as to integrated circuit micro-metrology.
Sicignano, A. and Iravani, M. Vaez
"Design and Applications of In-Situ Differential Scanning Electron Microscopy,"
Scanning Microscopy: Vol. 3
, Article 4.
Available at: https://digitalcommons.usu.edu/microscopy/vol3/iss1/4