THE CHECK OF THE ELASTIC-SCATTERING MODEL IN MONTE-CARLO SIMULATION

The coefficient of electron backscattering, the angular and energy dis tribution of transmitted electrons and of backscattered electrons have been calculated by the Monte-Carlo method using several models of ele ctron elastic scattering. The calculations were carried out for C, Al, Cu, Au, in the 10-100 keV energy range and in the 20-1000 nm film thi ckness range. Our findings were compared with published experimental r esults. The cross-section of elastic scattering was calculated either by Rutherford's formula (the screened atomic potential was assumed) or by Mott's theory including electron spin, or was taken from data tabl es computed from Hartree-Fock atomic wave functions. This provided an opportunity to decide which model of electron-atom elastic interaction is the best for simulation. The results showed that the backscatterin g coefficient, and mainly its dependence on him thickness and electron energy, is a quantity which is strongly sensitive to the model type. The best agreement between calculated and experimental data was reache d, in the full range of primary electron energies and film thicknesses , for Au and Al by using tables with rigorous partial wave calculation s and for Cu by using Rutherford's formula, even though the difference s among results for Cu are relatively small.