Simulation of the energy absorption and the resist development at sub-150Â nm ion lithography

The simulation tools for sub-150 nm ion beam lithography require more adequate models of the ion scattering, the energy losses and the development process. Accumulation and analysis of calculated results and physical parameters included in the models permit deeper understanding of the processes, comparison with experimental data and optimization of the simulation tools. Ion lithography of poly-methyl methacrylate of thickness up to 400 nm is studied. From the detailed simulation study, significant information on the energy losses, ranges and moments of the space distributions for different ions is obtained. It is concluded that the exposure with He ions with energies from 60 to 100 keV is favorable for sub-150 nm region. The presented energy absorption data confirm the importance of the electronic losses and the negligible effect of the nuclear losses on the local resist modification. Using simulation tools, accurate prediction of final resist profiles (after development) and analysis of obtained results at different process parameters of sub-150 nm structures is performed.