Research on Electron Emission from Dielectric Materials by a Monte Carlo Method

The charge accumulation in an insulating material under an electron beam bombardment exerts a significant influence to scanning electron microscopic imaging. This work investigates the charging formation process by a self-consistent Monte Carlo simulation of charge production and transportation based on a charge dynamics model. The charging effect in a semi-infinite SiO2 bulk and SiO2 trapezoidal lines on a SiO2 or Si substrate has been studied. We used two methods to calculate the spatial distributions of electric potential and electric field for two different systems respectively: the image charge method was used to deal with a semi-infinite bulk, and, random walk method to solve the Poisson equation for a complex geometric structure. The dynamic charging behavior depending on irradiation time has been investigated for SiO2. The simulated CD-SEM images of SiO2 trapezoidal lines with charging effect included were compared well with experimental results, showing the contrast change of SEM image along with scanning frames due to charging.