New three dimensional simulator for low energy (∼1 keV) electron beam systems

In this article, we describe the models and the results of a new three dimensional (3D) lithography simulation programs for low energy (similar to 1 keV) electron beam systems. Monte Carlo simulation was performed to obtain the energy intensity distribution in e-beam resists, and the models we have used were tabulated Mott data for elastic scattering, Moller and Vriens cross sections for inelastic scattering, and modified Bethe equation plus discrete energy loss for energy loss. The energy intensity in poly(methyl) methacrylate was calculated with the exposure simulation program with various pattern shapes. In the development simulation program, the 2D or 3D resist profile could be implemented. The ray tracing model and the Neureuther equation were used for the development simulation. The simulated developed depths as a function of energy were compared with experimental results developed by Rishton and Schock. The maximum deviation from the experimental results was 12.4 nm (6%) at 2500 eV, and all the data were within error range. The optimum condition was obtained and the positive and negative resist profiles for 50 nm line and space pattern were realized with our simulation program. (C) 1999 American Vacuum Society. [S0734-211X(99)10406-2].