Computer Simulation of Electron Scattering by Heavy Atoms Added into Resist for Dry-Etch Resistance Enhancement

Effects of heavy atoms added into resist for dry-etch resistance enhancement were explored by computer simulation of electron trajectories and absorbed energy density distribution in electron-beam lithography. Heavy atoms cause lateral spread of electron trajectories and resolution degradation. it was expected, however, that resolution would be improved by thinning the resist, thanks to dry-etch resistance improvement. A guide for heavy-atom-containing resist development was derived as the minimum resistance enhancement factor for various metals. Etching durability to withstand oxygen plasma is important, since it is used in the pattern transfer step in the double-layer resist process, which would be a key technology for submicrometer lithography. Quarter-micrometer lines are easily defined on the stepped surface, using the double-layer method with a Si containing resist, as foreseen from the simulation.