Charging damage during residual metal overetching

The influence of electron and ion temperatures on charging damage during residual metal (latent antenna) overetching in high-density plasmas is investigated by Monte Carlo simulations. The tunneling current through a thin gate oxide, electrically connected to the antenna, increases significantly with electron temperature, mainly as a result of changes in plasma current and ion energy distribution. However, the current decreases with ion temperature as ion shading: (a) directly decreases the ion flux to the antenna and (b) neutralizes the negative charge at the upper mask sidewalls, thus allowing more electrons to enter the pattern. The role of exposed antenna areas (trench bottoms and perimeter) is examined from the perspective of current imbalance.