Atomic layer Etching (ALE) is a self-limiting film etching technique employing surface-driven chemical reactions by alternating exposure of each chemical etchant species, and hence the desired thin film etch ideally undergoes in a layer-by-layer manner.
By virtue of the surface reaction feature of ALE, it has unique properties, such as excellent conformality (sometimes, to anisotropic z-direction in the use of plasma species), atomic scale fidelity, and large-area uniformity which are very essential prerequisite for advanced nanodevice fabrications.
Various forms of cyclic ALE reactions are schematically depicted in the right images, and for more information, please refer to the online video below.