Selective Atomic Layer Etching for Silicon Device Fabrication

This paper elaborates on the fundamentals of atomic layer etching (ALE) technique and reviews the methods to enable selective ALE for Si materials. Initially, the working principle of the ALE equipment is discussed. Subsequently, important process parameters that modulate the etch properties are elucidated. Some of these include, but are not limited to non-ideality, etch rate per cycle versus time (or dosage) and etch per cycle versus ion energy and anisotropy. In the latter half, challenges associated with ALE of silicon (Si) is elaborated. The selectivity mechanism towards Si, etch thickness per cycle (EPC) and impact if process parameters on the non-ideal nature of etching are elaborated. Finally, future scope and areas for improvement are concluded.