Modeling of electron elastic and inelastic scattering

The role of the form of the elastic and inelastic cross section in Monte Carlo simulations of electron-solid scattering has been studied to understand the processes whereby energy is deposited by electrons as they traverse thin films. Specifically we are interested in these phenomena as they relate to proximity effects in electron-beam lithography and the detection of electrons by a Schottky diode with a patterned absorber overlayer. Lithographic point and line spread functions have been measured in three resist materials. We show that the inclusion of discrete inelastic scattering events whereby fast secondaries are generated is essential for matching simulation and experiment. The secondaries are crucial in determining the shape of the spread functions in the 0.1-1 mu m regime and must be included to model proximity effects. Further, the fitting of line spread function simulations to experiment allows the accurate prediction of dot spread functions and applied dose thresholds as well as three dimensional resist profiles. The form of the elastic cross section is important in determining the energy loss in, and transmission through, thin metallic films. For electron energies where the film transmission is low, the Mott cross section provides a more accurate simulation than the screened Rutherford cross section.