Monte carlo simulation of energy dissipation in electron beam lithography including secondary electron generation

Abstract

A new Monte Carlo simulation including secondary electron generation has been performed to study energy dissipation in electron beam lithography. The simulation of inelastic scattering is calculated from the model of the generalied oscillator strength density distribution determined by a set of resonance energies and oscillator strengths. Varying the polmethyl-methacrylate film thicknes the energy dissipation profiles for various electron beam energies are evaluated. The effects of backscattered electrons from the silicon substrate and secondary electrons are studied with respect to film thicknesses and electron beam energies. The backscattered electrons from the Si substrate broaden the profiles, specially near the bottom layer and the secondary electrons broaden the profiles over the whole film. A time evolution of development process of the resist film is simulated using the string model. Higher enery beam developed sharper patterns than lower energy beam. The developed resist patterns are investigated with respect to distributions of the electron beam source and line/spaces, specially, in view of proximity effect. As the dose and width of the beam increase PMMA is developed winder and deeper and the proximity effect becomes more significant for the case of narrower space between lines.