Atomistic description of Si etching with HCl

Abstract

Silicon etching has found widespread application in the semiconductor industry over recent decades. However, the optimization of the utilized procedures has relied mainly on trial-and-error experimental approaches. Very few works have to-date tackled its atomistic simulation, and the mechanism behind the silicon removal remains poorly understood. In this work, we simulate all possible reaction steps of the etching process with Density Functional Theory, and we build a kinetic Monte Carlo model to study its dynamics. We characterize the energetics of the reaction mechanism, estimate the etch rates as a function of HCl pressure and temperature, and unveil the dominant gas-phase products for the different operando conditions, providing a solid theoretical background for process optimization. We find a remarkable agreement between our results and the reported experimental data.