Nanoscale Etching of In_0.53Ga_0.47As in H₂O₂/HCl Solutions for Advanced CMOS Processing

Abstract

An investigation of the surface chemistry of In0.53Ga0.47As in HCl/H2O2 solution for etching in the low etch rate range (<0.1–10 nm min−1) is described. Kinetic studies using inductively coupled plasma - mass spectrometry showed a surprizing result: the etch rate decreased with increasing chloride concentration, suggesting chlorine termination of the surface. This was confirmed by a determination of the relative chlorine coverage using total reflection X-ray fluorescence. These results are supported by contact angle measurements and surface oxide analysis with X-ray photoelectron spectroscopy. Reaction schemes based on chemical and electroless mechanisms are presented to help understand the surface chemistry. The etch rate range and the favorable surface roughness after etching as determined by atomic force microscopy show that this HCl/H2O2 system is an excellent candidate for advanced CMOS processing.