Simulation of Coulomb interactions in electron projection lithography using scattering contrast

Electron projection lithography (EPL), such as PREVAIL and SCALPEL, are among the candidates for next generation lithography. We modified the discrete Coulomb interaction simulator BOERSCH to be capable of incorporating the treatment of mask-scattered electrons into the simulation domain. Annular apertures of arbitrary number and size also can be set as the limiting aperture in addition to the usual round shape. Using this simulator, not only the resolution but also the performance of the SCALPEL GHOST proximity effect correction (PEC) can be evaluated. Therefore, this modified BOERSCH can provide almost perfect functions necessary for the EPL process development.