Optimizing the detector configuration for SEM topographic contrast using Monte Carlo simulation

摘要

The relation between detector geometry and image contrast was studied using the Monte Carlo simulator, CHARIOT. The simulator is capable of modeling electron scattering in the specimen, but it can also model the electron trajectories outside the specimen under 3-D electric and magnetic fields as well as the detector energy response. SEM images of 10 nm thick structures on a flat substrate were examined. The results demonstrate that the image contrast changes more drastically by changing the angular window of the detector, rather than by changing the energy response function of the detector. Particularly, it is shown to be possible to optimize the image contrast and the contrast-to-noise ratio of the SEM image. The information obtained is useful for designing the SEM detector for specific applications.