Dry etching characteristics of AlGaN/GaN heterostructures using inductively coupled H2/Cl2, Ar/Cl2 and BCl3/Cl2 plasmas

In this paper, the etching properties of AlGaN/GaN heterostructures were studied by using inductively coupled H-2/Cl-2, Ar/Cl-2 and BCl3/Cl-2 plasmas. Atomic force microscope (AFM) measurement showed that distinct surface morphology were obtained using different gas chemistries. Ultra-smooth etched surface with the root-mean-square roughness of 0.851 nm has been achieved using BCl3/Cl-2 chemistry, which is the best result for the etching of AlGaN/GaN heterostructure using inductively coupled plasma (ICP) to our knowledge. Surface analysis was then performed to understand the etching characteristics by Auger electron spectroscopy (AES). We find that the effective removal of oxygen from the etched surface of AlGaN layer during the etching process was a crucial factor in enhancing the surface morphology of the etched samples.