Effect of adding CO2 to CH4/H-2 mixture for InGaAs/GaAs selective reactive ion etching

InGaAs/GaAs selective reactive ion etching (RIE) by adding CO2 to a conventional CH4/H-2 mixture was developed for the first time. We demonstrated that adding CO2 (7.8%) not only reduced polymer deposition during etching, but also achieved a significant increase in the In0.52Ga0.48As/GaAs selectivity from 2 to a maximum value of 6.5. We analized the etched surface with X-ray photoelectron spectroscopy (XPS) and found that the surface is polymer-rich after the CH4/H-2 RIE, but it changes to Ga2O3-rich after our CH4/H-2/CO2(7.8%) RIE. From this result, we proposed a mechanism of the InGaAs/GaAs selective RIE.