Elemental behaviors of InGaAs surface after treatment in aqueous solutions

Abstract

Indium gallium arsenide (InGaAs) is one of the candidates as a channel material for the high-performance complementary metal-oxide-semiconductor (CMOS) devices superior to silicon-based CMOS devices because of its higher electron mobility. In order to introduce InGaAs as a new channel material for high-performance CMOS devices, it is important to prepare its surface to suppress material loss and surface oxide formation in the InGaAs layer. In this study, the behavior of each element of the In0.53Ga0.47As surface in chemical solutions such as HCl, NH4OH, HPM (HCl/H2O2/H2O) and APM (NH4OH/H2O2/H2O) was investigated from the viewpoint of thermodynamics and reaction kinetics. In the acidic HCl solution, the dissolution of the InGaAs surface was the dominant reaction, whereas a sub-oxide formed on the InGaAs surface in the basic NH4OH solution. The formation of the oxide on the surface was considered the rate-limiting step of the overall etching reaction of InGaAs in the acidic solution; therefore, the surface oxidation and overall etching (dissolution) of the InGaAs layer were determined using different amounts of H2O2 in the solution. In particular, the overall etching of the InGaAs surface in the HPM solution was more aggressive than that in the APM solution. The behavior of InGaAs in the surface preparation process sequences with APM, HPM, and HF was also investigated, and it was observed that the material loss and surface roughening of the InGaAs layer were mostly determined in the HPM process. Finally, it was possible to suppress the surface oxidation, material loss, and surface roughening of the InGaAs layer by reducing the concentration of H2O2 in the HPM solution.