  We propose a theoretical study for Si thin film thickness measurement that is
based on incident low energy electron beam on the film and counting the
transmitted/incident electron fraction. It estimates the thin film thickness
distribution from a exponential relation which obtained from counting the
fraction of transmitted/incident electron at different thicknesses. By using
this obtained equation, it is possible to estimate unknown thickness of the Si
thin film. In order to calculate the Si thin film thickness estimation, the
energy of the incident electron beams is varied from 6-12 keV, while the
thickness of the Si film is varied between 100-400 nm. The most significant
feature of this method is that no expensive instruments are required. As
anticipated, the proposed method shows that there is a relationship between
film thickness and incident beam energy, which by using this relationship, we
can find unknown film thickness in 1-D and 2-D conditions. Other advantages
include wide measurement range, no calibration need and simple method.
Additionally, an investigation by different beam energies helps to avoid
artefact from this method. All calculations were done by CASINO numerical
simulation package.
