Three-dimensional geometrical modeling of plasma transfer effects on line edge roughness: comparison with experiments and rules of thumb

The transfer of the line edge roughness (LER) from the resist to the substrate sidewall by means of an anisotropic plasma-etching process depends on both the physicochemical reactions of plasma species with the resist and substrate and the morphology of the resist sidewalls. We show that a geometrical model based on the reliable representation of the resist sidewall roughness can capture the main experimental trends and behaviors. Predictions of the model regarding the role of resist sidewall anisotropy and the effects of resist LER on substrate slope are also presented. Finally, rules of thumb defining the slope and the necessary conditions to have LER reduction in substrate sidewalls are derived and discussed. (C) 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)