Dry etching of epitaxial InGaAs/InAlAs/InAlGaAs structures for fabrication of photonic integrated circuits

A dry etching process to transfer the pattern of a photonic integrated circuit designfor high-speed laser communications is described. The laser stack under consideration is a3.2-mu m-thick InGaAs/InAlAs/InAlGaAs epitaxial structure grown by molecular beam epitaxy.The etching was performed using Cl2-based inductively-coupled-plasma and reactive-ion-etching(ICP-RIE) reactors. Four different recipes are presented in two similar ICP-RIE reactors, withspecial attention paid to the etched features formed with various hard mask compositions,in-situpassivations, and process temperatures. The results indicate that it is possible to producehigh-aspect-ratio features with sub-micron separation on this multilayer structure. Additionally,the results of the etching highlight the tradeoffs involved with the corresponding recipes. (c) 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement