Plasma Application in Atomic Layer Etching

Atomic layer etching (ALE) has emerged as a promising technique for the precise and controlled removal of materials in nanoscale devices. ALE processes have gained significant attention due to their ability to achieve high material selectivity, etch uniformity, and atomic-scale resolution. This article provides a perspective of the important role of plasma in ALE including thermal ALE for nanometer-scale device manufacturing. Advantages as well as challenges of ALE are discussed in contrast to classic reactive ion etching. A tally-up of known plasma-based ALE processes is listed, and novel thermal ALE processes are described that are based on the so-called ligand addition mechanism. We explain the potential of using plasma for increasing wafer throughput in a manufacturing environment, its use when it comes to anisotropy tuning, the benefits in enabling a wider range of pre-cursors in thermal ALE, and the advantages it may bring for thermal ALE of crystalline materials. The benefits and challenges of different plasma sources in ALE are discussed, and an outlook for future development is provided. Finally, applications of plasma for productivity reasons such as particle avoidance and process stability are outlined.