Atomic layer etch (ALE)

Why the concentration exists

Atomic layer etching removes individual atomic layers using a sequence of self-limiting chemical modification and etching steps. The process separates the adsorption and reaction steps, repeating each cycle to control etching depth at the nano-level. The standard example etches silicon by alternating reaction with chlorine and etching with argon ions. This sequential approach yields controlled etching at the atomic level, which is required as device feature sizes shrink and demand greater accuracy for peak performance.[4][13][21][2]

Two principal types of atomic layer etching exist: thermal and plasma-based. Plasma ALE performs directional etches that are anisotropic and is currently in production, expanding into applications beyond traditional silicon such as gallium-nitride and refractory metals. Thermal ALE performs unidirectional etches that are isotropic and remains in its infancy, with researchers targeting it for next-generation transistors. Al2O3 ALE serves as the model thermal ALE system, based on fluorination and ligand-exchange reactions.[7][9][21]

Plasma enhancement has made atomic layer etching a thousand times faster than earlier approaches, transforming a technique once considered too slow for practical use. Removal rates of one atomic layer per second are around the state of the art for commercial atomic layer etching. Reported cycle times for etching silicon film typically vary from approximately one minute to over five minutes, with corresponding etch rates of roughly 0.1 to 0.01 nm per minute. ALE achieves etch rates of 2 to 7 Angstroms per cycle in practice.[1][10][11][13][19][14][17]

What the evidence shows

Who supplies it

Lam Research introduced dielectric atomic layer etching capability on its Flex dielectric etch systems, achieving the first plasma-enhanced ALE process for dielectric films running in production for high-volume manufacturing of logic devices as of September 6, 2016. This process, enabled by Lam's Advanced Mixed Mode Pulsing technology, demonstrated a two-times improvement in selectivity over previous dielectric etch technologies. Lam's Flex system with dielectric ALE was adopted as the tool of record for high-volume manufacturing of logic devices at 10 nm and below.[12][15]

What it depends on, and what depends on it

Atomic layer etch processes have been demonstrated for materials including Al2O3, HfO2, ZrO2, ruthenium, copper, and nickel, as reported in studies from 2015 to 2025. Cl2/Ar ALE for GaN HEMT gate recess etching achieved an etch per cycle of approximately 1.5 Angstroms per cycle and a ten-times reduction in surface trap density compared to conventional ICP-etched surfaces. Cl2/Ar ALE at 60 degrees Celsius for GST maintained the stoichiometric ratio of Ge:Sb:Te to within plus or minus 3% of the target 2:2:5 composition, versus plus or minus 15% variation with continuous ICP-RIE.[8][20]

Oxford Instruments announced on May 22, 2026 that Rigetti Computing has purchased a PlasmaPro 100 Cobra atomic layer etch system for dedicated fabrication of quantum devices. Rigetti Computing launched the world's first dedicated quantum foundry, Fab-1, in 2017. Oxford Instruments' ALE technology delivers a smooth low-damage etch process for next-generation quantum devices. The system demonstrated 25 nm wide silicon trenches etched to 110 nm depth, with AlGaN surface roughness improving from Ra equals 600 picometers to 300 picometers after 200 ALE cycles.[16][18][17]

Where it sits in the stack

What would break it

Changes in the state of reactor surfaces and enhanced supply of reactants from passive surfaces such as walls by plasma-wall interactions could potentially lead to loss of control over the supply of chemical precursors to active surfaces. This creates a highly dynamic environment where species transport between different surfaces can easily take place. The ALE energy window for silicon with Cl2/Ar is relatively wide at approximately 15 to 60 eV, while some III-V materials have narrower windows requiring more precise bias control. These process control challenges increase as materials diversify beyond silicon.[3][20]

The atomic layer processing community must focus on developing candidate chemistries which can meet the rigorous demands of high-volume manufacturing. Thermal ALE, which performs isotropic etches, is still in its infancy with some targeting it for next-generation transistors. The University of Colorado presented work on thermal ALE for metal gates and dielectrics, while the University of Delaware presented work on thermal ALE for metals and alloys. This suggests an emerging technology frontier that could expand ALE applications if chemistry development succeeds.[6][9]

New entrants and increasing competition are expected in the competitive landscape, with a focus on emerging markets in Asia-Pacific. AlixLabs in Sweden has been granted a European patent for Atomic Layer Etch Pitch Splitting technology as of October 24, 2022. The APS method uses sidewalls as a topographical mask in atomic layer etch processes and has been proven for gallium phosphide, silicon, and tantalum nitride. AlixLabs has secured granted US and Taiwan patents in addition to the European patent, with more patent applications in the pipeline.[5][24]

What to watch

Plasma atomic layer etching of ruthenium using an oxygen adsorption-removal cyclic process was reported by Kim et al. in 2024. Copper atomic layer etching by oxidation and formic acid vapor was studied by Smith et al. in 2025. These recent material demonstrations indicate ongoing expansion of ALE process capability beyond traditional silicon etching. The progression from 2015 through 2025 shows continuous development of ALE processes for an expanding materials set.[8]

AlixLabs patent US20250087487A1, allowed on May 6, 2025, combines self-aligned double patterning with atomic layer etching-based pitch splitting. This intellectual property development could enable new approaches to pitch splitting that leverage ALE's atomic-level precision. Applied Materials holds numerous patents for atomic layer etch processes, including selective dry-etch rate suppression of materials containing both silicon and oxygen and both silicon and nitrogen. Lam Research holds patents for mixed mode pulsing etching in plasma processing systems related to atomic layer etch.[22][23]

Related nodes

Sources

1. pubs.acs.org
2. nanovactech.com
3. iopscience.iop.org · 2015-03-27T00:00:00
4. samcointl.com · 2025-02-19T01:50:21
5. cognitivemarketresearch.com · 2025-07-05T17:57:45
6. atomiclimits.com
7. pubs.aip.org · 2023-08-16T00:00:00
8. link.springer.com · 2024
9. semiengineering.com
10. semiengineering.com · September 20th, 2018
11. newsroom.lamresearch.com · 2018-09-04
12. investor.lamresearch.com · 2016-09-06
13. en.wikipedia.org
14. sst.semiconductor-digest.com
15. sst.semiconductor-digest.com
16. oxinst.com · 22 May 2026
17. plasma.oxinst.com
18. marketscreener.com · 2026-05-22
19. mobilityforesights.com · 2025-04-27
20. ninescrolls.com
21. avs.org
22. alixlabs.com · 2025-05-06
23. patents.google.com
24. eenewseurope.com · October 24, 2022