Modeling of the chemically assisted ion beam etching process: Application to the GaAs etching by Cl2∕Ar+

Abstract

The development of two-dimensional chemically assisted ion beam etching model of GaAs by Cl2∕Ar+ allowed the authors to analyze the role of some critical parameters of etch process on the morphology of trench and mesa structures. In a fact, the simulation results show that the etch rate variation with substrate temperature Ts reveals three regimes: For Ts<350K, the etch rate of GaAs is mainly controlled by ion assisted etching component. For 350<Ts<TM, where TM corresponds to the maximum of etch rate, a high variation of etch rate is observed. In this range of temperature, the etch rate is controlled by the chemical component and mainly by the exponential rise of desorption coefficient of GaClx,λ3, with Ts. For Ts>TM a fast decrease of the etch rate is observed because of the high decrease of the coverage rate of Cl, ξ, on the gallium sites with the substrate temperature. On the other hand, the increase of the Cl2 flow rate allows to improve the anisotropy and contributes to the elimination of both the microtrenching and the transfer of the facets from the mask into the substrate.