Recovery Methods of Gallium Nitride Plasma Etch Damage

The semiconductor surface state is of crucial importance for any MOS device. Conventional dry etch processing steps, however, damage the wafer surface, which might degenerate the electrical performance of the device. In this paper, we compare different approaches to recover the Gallium Nitride (GaN) surface, including dry atomic layer etching (ALE), cyclic wet digital etch (DE), and static treatment in tetramethylammonium hydroxide (TMAH). None of these methods are able to restore the initial pristine state after intentionally induced damage, but they can significantly reduce the RMS roughness measured with Atomic Force Microscopy (AFM). We conclude that short static hot TMAH treatment represents the best combination of surface recovery and industrial scalability.