Monte-Carlo simulation of the effects of vacuum ultraviolet radiation on electronic materials

Radiation induced damage during the plasma processing of semiconductor materials adversely affects device reliability. Our group has shown in the past that Vacuum Ultraviolet (VUV) radiation (10nm-200nm) can beneficially deplete the charge deposited on the surface of the semiconductor by temporarily increasing the conductivity of the dielectric. The increase in conductivity has mainly been attributed to the generation of photoemission current and formation of electron hole pairs in the dielectric. In this paper, we discuss the steps involved in developing a model for VUV-semiconductor dielectric interactions based on the well-known Monte Carlo method. The statistical information obtained from this simulation will be compared to the experimental values obtained by exposing silicon nitride wafers to synchrotron radiation of energy 20eV. The simulation predicts the surface potential on the wafer due to photoemission. Experimentally measured surface potentials on the dielectric are used to check the validity of the simulation. Of the different process that can occur when a photon is incident on an atom, we concentrate mainly on photoemission of an electron. Consequently, the elastic and inelastic scattering events experienced by the electron during the course of its motion inside the dielectric are also considered. A modified form of the screened Rutherford formula, which approximates the Mott cross-section, as developed by Browning et. al., has been applied in this simulation. Initial simulation results will be presented.