ALE is an emerging dry etch technology capable of etching semiconductor structures with a precision down to single atomic layers. It employs a technique analogous to ALD whereby the etchant gases are individually introduced into the etch chamber in an alternating sequence. This is different to conventional plasma etching recipes which typically use a mixture of several gases during a single etching step. Like ALD, atomic layer etching uses repeated processing cycles, and the etch chemistry is chosen to form a self-limiting monolayer on the substrate surface.
As semiconductor processing is scaled down below the 10nm node, it is expected that the ALE technique will be required to etch nm-scale FinFET and similar advanced transistor structures.
Available literature suggests that the ALD technique will use many of the same gases used in conventional RIE etching, including: Ar, F2, Cl2, BCl3, HBr.