Atomic layer etching of InGaAs by controlled ion beam

Atomic layer etching (ALE) could be an important next-generation etching technique, applicable to various semiconductor materials including III-V compound materials such as indium gallium arsenide (InGaAs) which has high carrier mobility, an advantageous characteristic in nanoscale electronic devices. In this study, the ALE characteristics of InGaAs have been investigated using a reactive ion beam technique. For the ALE of InGaAs, chlorine radicals/low-energy (10-19 eV) reactive ions and low-energy (5-8 eV) Ar⁺ ions were used for adsorption and desorption, respectively, during the etch cycle to precisely control the etch depth and to minimize the surface damage of the InGaAs. By using the ALE technique, a constant etch rate of 1.1 Å/cycle could be obtained for InGaAs, as well as an infinite etch selectivity of InGaAs over various materials such as photoresist, silicon, amorphous carbon layer, SiO₂, and HfO₂. The surface composition and surface roughness of the InGaAs after ALE were similar to those of as-received un-etched InGaAs.