Thanks to such salient performance benefits as uniformity across all length scales and selectivity, atomic layer etching is being proliferated in production. Directional ALE was the first process to go into production because most critical etch applications require directionality. Isotropic ALE is an emerging branch based on chemical reactions akin to those uses in thermal ALD. The term “isotropic” means that the etch proceeds in all directions. This property is particularly valued in vertical device integration where materials need to be removed from vertical and concealed surfaces.
In this talk, a conceptual framework for directional and isotropic ALE will be introduced to explain the performance benefits and limitations of both technologies. Experimental and theoretical results as well as applications examples will be presented to illustrate the concepts.