Resolution analysis in electron-beam cell projection lithography system

Abstract

We have experimentally analyzed the resolution in electron-beam cell projection lithography systems. The results indicated that the Coulomb interaction effect and the proximity effect are critical issues for resolution because of the larger beam current compared with the conventional variable-shaped beam. We achieved a practical resolution of 0.18 μm, which is enough for 1 Gbit dynamic random access memory (DRAM) fabrication, by adjusting the beam current. We have also found that there is some interaction between the individual line beams (streams). Also, the beam profile degradation in cell projection lithography systems depends not only on the beam current but also on the distance between the streams. Therefore, in order to obtain higher resolution, these effects must be considered more carefully than in the case of conventional variable-shaped beam lithography systems. A resolution of less than 0.15 μm, which is required for Gbit level DRAM fabrication, can then be available in cell projection lithography systems.