Atomic layer etching

{{short description|Method that removes material, one 1-atom thick layer at a time}}

Atomic layer etching (ALE) is an emerging technique in semiconductor manufacture, in which a sequence alternating between self-limiting chemical modification steps which affect only the top atomic layers of the wafer, and etching steps which remove only the chemically-modified areas, allows the removal of individual atomic layers. The standard example is etching of silicon by alternating reaction with chlorine and etching with argon ions.

This is a better-controlled process than reactive ion etching, though the issue with commercial use of it has been throughput; sophisticated gas handling is required, and removal rates of one atomic layer per second are around the state of the art.{{cite web | url=http://semimd.com/blog/2014/08/04/atomic-layer-etch-now-in-fab-evaluations/ | title=Atomic Layer Etch now in Fab Evaluations | date=2014-08-04 | access-date=2015-05-29 | archive-date=2017-07-15 | archive-url=https://web.archive.org/web/20170715234646/http://semimd.com/blog/2014/08/04/atomic-layer-etch-now-in-fab-evaluations/ | url-status=dead }}

The equivalent process for depositing material is atomic layer deposition (ALD). ALD is substantially more mature, having been used by Intel for high-κ dielectric layers since 2007 and in Finland in the fabrication of thin film electroluminescent devices since 1985.{{Cite journal|last=Puurunen|first=Riikka L.|date=2014-12-01|title=A Short History of Atomic Layer Deposition: Tuomo Suntola's Atomic Layer Epitaxy|journal=Chemical Vapor Deposition|language=en|volume=20|issue=10–11–12|pages=332–344|doi=10.1002/cvde.201402012|issn=1521-3862|url=https://zenodo.org/record/3228179|doi-access=free}}