THE ROLE OF THE SUBSTRATE ON PATTERN-DEPENDENT CHARGING

Monte Carlo simulations of charging and profile evolution during plasm a etching reveal that the substrate can mediate current imbalance acro ss the wafer. This function couples patterned areas, where the electro n shading effect dominates, to substrate areas directly exposed to the plasma. When a net positive current flows through the pattern feature s to the substrate, increasing the exposed area decreases the substrat e potential, thereby causing notching at the connected feature sidewal ls to worsen, in agreement with experimental observations.