Pattern-Dependent Charging in Plasmas: Electron Temperature Effects

The differential charging of high-aspect-ratio dense structures during plasma etching is studied by two-dimensional Monte Carlo simulations. Enhanced electron shadowing at large electron temperatures is found to reduce the electron current density to the bottom of narrow trenches, causing buildup of large charging potentials on dielectric surfaces. These potentials alter the local ion dynamics, increase the flux of deflected ions towards the sidewalls, and result in distorted profiles. The simulation results capture reported experimental trends and reveal the physics of charging damage.