Atomic Layer Etching: Process, Material Compatibility and Advances in Applications

Atomic layer etching (ALE) is a material removal technology with atomic-level precision based on a cyclic "surface modification-etching" process. Owing to the excellent performance including self-limiting monolayer removal, high selectivity, and three-dimensional uniformity, ALE has been extensively applied in semiconductor manufacturing, nanodevice processing, and optoelectronic device development, among other fields. Depending on energy-driven mechanisms, ALE technologies are primarily categorized into thermal atomic layer etching (T-ALE), laser atomic layer etching (L-ALE), ion beam atomic layer etching (IB-ALE) and plasma atomic layer etching (P-ALE). This review summarizes the fundamental principles, process characteristics, and recent advancements of various ALE technologies, with a focus on the latest applications of plasma atomic layer etching (P-ALE) in silicon-based materials, silicon nitride, silicon oxide, and transition metal compounds. Furthermore, in comparison to international developments, the review highlights challenges for domestic ALE technologies, including the need for breakthroughs in multi-material compatibility, process stability, and eco-friendly precursor development. Finally, the future development of ALE technique has been prospected, encompassing laser-plasma hybrid processes, machine learning-driven intelligent control, and low global warming potential gas alternatives, which provides theoretical support for the research and application of next-generation atomic-scale manufacturing technologies.