Continuous Cellular Automaton for the simulation of the surface morphology on any silicon orientation Si{HKL} in anisotropic etching

Abstract

A Continuous Cellular Automaton (CCA) is modified to incorporate a micromasking model and a removal rate restriction function in order to address the formation of morphological instabilities during anisotropic wet etching. As an example, the etching of crystalline silicon in KOH with isopropanol is considered (12% KOH+IPA). By combining the micromasking model with site-specific atomistic removal rate values previously calibrated by matching the macroscopic orientation-dependence of the etch rate, a good agreement with the experimental surface morphologies for a wide range of crystalline orientations {h k l} is obtained. This is in contrast to traditional Kinetic Monte Carlo (KMC) studies where the site-specific rates are calibrated by matching the surface morphologies but the orientation-dependence of the etch rate is not described correctly. The modified CCA makes possible the realization of accurate simulations of anisotropic etching in realistic engineering applications.