Charging phenomena of polymer films on silicon substrates under electron beam irradiation are studied by numerical simulation. The initial distribution of the charge deposited in the sample is calculated by a Monte Carlo simulation of electron scattering, and charge drift is simulated by taking into account the Poisson equation, the charge continuity equation, Ohm's law, and electron beam induced conductivity. The dependences of charging on electron energy and polymer thickness are explained by the secondary yield and the relationship between the electron range and polymer film thickness.

The time-dependent charge distribution in polymer film under electron beam irradiation is studied by both experiment and numerical simulation. In the experiment, the distribution is measured with the piezoinduced pressure wave propagation method. In the simulation, the initial charge distribution is obtained by the Monte Carlo method of electron scattering, and the charge drift in the specimen is simulated by taking into account the Poisson equation, the charge continuity equation, Ohm’s law, and the radiation-induced conductivity. The results obtained show that the negative charge deposited in the polymer film, whose top and bottom surfaces are grounded, drifts toward both grounded electrodes and that twin peaks appear in the charge distribution. The radiation-induced conductivity plays an important role in determining the charge distribution in the polymer films under electron beam irradiation.