Analysis of lateral resolution and contrast of scanning capacitance microscopes

The contrast formation and the accuracy of the capacitance sensed by the probe of a Scanning Capacitance Microscope have been simulated using the Finite Element Method. Shielded macroscopic probes and sharp microfabricated AFM tips have been assumed. The modelled objects were cylindrical protrusions and depressions at the bottom of insulating films, and simplified metal–oxide–semiconductor structures containing cylindrical wells with doping level differing from their neighbourhood. Due to the stray field of the probes an “exact” measurement of the local capacitance is only possible if the diameter of inhomogeneities is as large as a hundreds to thousands nm.