Energy transfer between electrons and photoresist: Its relation to resolution

In the study of high-energy photon and electron lithography the photoresist has been treated as a uniform and isotropic medium. As dimensions become smaller and exposure fluctuation more noticeable, we cannot ignore the processes that happen at the molecular scale. Hence, it becomes important to understand how the energy is coupled from an exciting radiation to the various molecular components of a photoresist material. In this article, we present the first step in the development of such a model. We base the analysis on the method of virtual quanta for the incoming electron, and use the dielectric function response theory to describe the medium. The results correctly describe the decreasing strength of the interaction on the electron energy, and yield an estimate of ≈2–3 nm for an average interaction distance. A simple Monte Carlo simulation is implemented to verify the effect of the fluctuations due to the virtual quanta on a line edge.