Effect of the chloropentafluoroethane additive in chlorine-containing plasma on the etching rate and etching-profile characteristics of gallium arsenide

In this study, the dependence of the plasma-chemical-etching rate and the surface roughness of a gallium-arsenide crater on the concentration of chloropentafluoroethane (C$_{2}$F$_{5}$Cl) in a mixture with chlorine, the capacitive discharge power, and the etching duration are investigated. The characteristics of the GaAs etching crater are studied by white-light interferometry and scanning electron microscopy. It is shown that the addition of C$_{2}$F$_{5}$Cl into the chlorine-containing inductively coupled plasma leads to a nonlinear change in the gallium-arsenide etching rate with time, which can be explained by passivation of the substrate surface at the initial stage by the products of freon decay. Along with this, characteristics of the etching profile of GaAs are substantially improved. An increase in the capacitive discharge power promotes the development of roughness, while the etching rate increases nonlinearly.