Paper NM-ThP3
Atomic Layer Etching of Cl-Adsorbed GaAs by Using a Low-Angle Forward Reflected Ne Neutral Beam

Thursday, October 23, 2008, 6:00 pm, Room Hall D

GaAs compound-based semiconductors are currently investigated for various devices such as high efficiency solar-cell, high mobility electronic devices, optical devices, etc. due to direct band structure, high electron mobility, high operating temperature range, etc. For the processing of gallium arsenide (GaAs), conventional dry etching processes such as chlorine-based inductively-coupled plasma (ICP) are used but they tend to cause physical damage on the surface due to the irradiation of high energy ions during the etching, and which results in the degradation of the devices. Therefore, the removal of surface damage during the processing is essential and, among the various dry etching processes, atomic layer etching (ALET) has been studied to realize atomic scale etch-rate controllability of GaAs without physically damaging the surface of GaAs. In this study, the characteristics of ALET for (100)/ (111) GaAs have been investigated as functions of Cl₂ pressure during the adsorption stage and Ne neutral beam irradiation dose during the desorption stage. By using the Ne neutral beam dose and the Cl₂ pressure higher than the critical values of 3.03×10¹⁶ atoms/cm²•cycle and 0.4 mTorr, respectively, one monolayer etching condition of 1.41 Å/cycle for (100) GaAs and 1.63 Å/cycle for (111) GaAs could be obtained through the adsorption of one monolayer of Cl₂ during the adsorption stage and desorption of all of the chlorides formed on the surface by the sufficient Ne neutral beam irradiation. At the monolayer etching conditions, the surface roughness was the lowest and was similar to that of as-received GaAs. Therefore, the use of ALET condition enabled us to control the etch depth with an atomic-scale precision without damaging the surface physically or chemically.