MODELING OF ASPECT RATIO DEPENDENT ETCHING

摘要

We present a study of aspect ratio dependent etching (ARDE) in reactive ion etching (RIE) systems. EVOLVE, a transport and reaction simulator, is employed to reveal trends in simple chlorine etching of silicon. Models of transport and reaction in low Knudsen number regimes of both ionic and neutral species are addressed, and ARDE is evaluated in the context of competing processes and characterized via parameters such as neutral-to-ion flux ratio and feature geometry. The predicted aspect ratio dependencies are then compared to those those of similar processes from the literature in order to reveal underlying trends in RIE systems. Our study of the Si-Cl etching process is used to demonstrate a methodology for the development of engineering correlations of transport-controlled etch processes through the use of simple but flexible models for transport and reaction kinetics. We demonstrate that simulations using simple models of transport and reaction have the potential to establish semi-quantitative trends. These models may be calibrated via experiment and used to interpolate to regions for which data do not exist.