Monte Carlo simulation of electron transmission through the scattering masks with angular limitation for projection electron lithography

Abstract

We calculated electron energy loss and angular distributions for electrons transmitted through masks for electron projection lithography by a Monte Carlo (MC) simulation method. After comparing the improved continuous slowing down approximation model, the direct MC model, and the intensive direct MC model, the last model was used. The energy loss distributions calculated by the latter two models are much better than by the first model and the intensive direct MC model can be applied to more materials than the direct MC model. The effect of mask thickness on energy loss, transmission, and contrast was analyzed. We found that, for a W/Cr/Si3N4 mask, the thicker the scattering layer the wider the angular distribution, the lower the transmission, and the higher the contrast. But the thickness of the membrane Si3N4 layer has less effect on the contrast.

Long nanoscale gaps on III–V substrates by electron beam lithography

“…It is worth noting that the dose is uniform not only along the gap, but also vertically, because 100 kV electrons lose only about 3 eV/nm when penetrating resist. 13 Nor is there significant lateral scattering through this thickness of resist; the only variation is orthogonally to the gap. The energy density within both the gap and the directly exposed region can be considered uniform because the gap size is small compared not only to the backscattered electron range, but also to the range of fast secondary electrons.…”

Monte Carlo Simulation of Projection Electron Beam Lithography

“…The extensive direct MC model [8,14] has been used to calculate electron transmission through a mask and the energy deposition in the resist. The primary electron energy considered here is 120 keV, and thus the relativistic form is adopted for each theoretical formula.…”