Anisotropic/isotropic atomic layer etching of metals

To determine a suitable etching method for the fabrication of semiconductors with a few nm or less thickness, many atomic layer etching (ALE) techniques have been studied. Previously, ALE studies on silicon-based materials have been reported; however, recently, the number of ALE studies on metals have also been increasing. Metals are applied to semiconductor devices as electrodes and hard mask materials, thus, there is an increasing need for precise etching using ALE techniques. Therefore, in this brief review, recently reported ALE studies on metals will be summarized, and the ALE process results for various metals will be described for two ALE methods, namely, anisotropic ALE and isotropic ALE.