Inductively coupled plasma etching of AlGaN using Cl_2/Ar/BCl_3 Gases

摘要

AlGaN is am important ultraviolet optoelectronic material and inductively coupled plasma (ICP) etching plays an important role in fabrication of mesa structures of AlGaN-based photodiodes. In this work, we investigate ICP etching processes of Al_(0.32)Ga_(0.68)N and Al_(0.47)Ga_(0.53)N. The Al_(0.32)Ga_(0.68)N and Al_(0.47)Ga_(0.53)N materials were firstly tested by transmission spectra and it indicates that they are different materials with different epitaxial quality. Cl_2/Ar/BCl_3 were used as the ICP gases, and Cl_2/Ar mixing ratio was fixed at 4:1. Etching behaviors were characterized by varying the ICP power, the dc bias, Cl_2/Ar/BCl_3 mixing ratio. ICP power influences etching rates. Dc bias heavily influences the etching rates, and the etching rates increase monotonously with dc bias, which suggests that the ion-bombardment effect is an important factor of these etching processes. BCl_3 is the effective removal of oxygen during the etching, and also influences etching rates. The surface rms roughness was measured by an at omic force microscope. The ICP etching surface morphologies were studied by Scanning Electron Microscope (SEM). The results show dc bias and BCl_3 are important to electrical characteristics of epitaxial materials. At a relative high dc bias and more BCl_3, the etching rate is low, but the damage is low. These results have direct application to the fabrication of AlGaN-based ultraviolet optoelectronic devices.