Atomic layer deposition: building a film one layer per cycle

Atomic layer deposition of alumina drawn as a coil, one turn per cycle: a trimethylaluminium pulse, a purge, a water pulse and a purge, each half-reaction stopping by itself, so every cycle adds the same sub-monolayer. Below, the self-limiting chemistry, conformal coating of deep trenches and particles, and uses in chips, batteries and catalysts.

1. TMA pulse: The precursor reacts with the surface until the reactive sites are used up: self-limiting chemisorption (Oviroh et al. 2019). 2. Purge: Purge gas clears the excess precursor and by-products (methane, in the TMA reaction) before the next pulse (Oviroh et al. 2019). 3. Water pulse and purge: The second half-reaction completes the layer; TMA and water is the most widely used ALD chemistry and gives amorphous Al₂O₃ (Young et al. 2020). 4. Repeat: Each cycle adds the same (sub)monolayer: 1.4–1.5 Å per cycle for TMA/water alumina in long capillaries (Patel et al. 2022). 5. Uses: Conformal gate oxides and DRAM capacitors (Oviroh et al. 2019), 14 nm Al₂O₃ protecting lithium metal (Kozen et al. 2015), overcoats that stop copper catalysts sintering (O’Neill et al. 2013).

Starting materials: Trimethylaluminium (TMA) and water vapour, pulsed in turn with purges between. Product: A conformal amorphous Al₂O₃ film whose thickness is set by the number of cycles.

Oviroh et al., “New development of atomic layer deposition: processes, methods and applications”, Sci. Technol. Adv. Mater. 2019 (doi:10.1080/14686996.2019.1599694); Patel et al., “Flow-Through Atmospheric Pressure-Atomic Layer Deposition Reactor for Thin-Film Deposition in Capillary Columns”, Anal. Chem. 2022 (doi:10.1021/acs.analchem.1c05029); Young et al., “Probing the Atomic-Scale Structure of Amorphous Aluminum Oxide Grown by Atomic Layer Deposition”, ACS Appl. Mater. Interfaces 2020 (doi:10.1021/acsami.0c01905); Fryauf et al., “Scaling Atomic Layer Deposition to Astronomical Optic Sizes: Low-Temperature Aluminum Oxide in a Meter-Sized Chamber”, ACS Appl. Mater. Interfaces 2018 (doi:10.1021/acsami.8b10457); Kozen et al., “Next-Generation Lithium Metal Anode Engineering via Atomic Layer Deposition”, ACS Nano 2015 (doi:10.1021/acsnano.5b02166); O'Neill et al., “Stabilization of copper catalysts for liquid-phase reactions by atomic layer deposition”, Angew. Chem. Int. Ed. 2013 (doi:10.1002/anie.201308245); Madadi et al., “Atomic and Molecular Layer Deposition of Alkali Metal Based Thin Films”, ACS Appl. Mater. Interfaces 2021 (doi:10.1021/acsami.1c17519); George, Yoon & Dameron, “Surface chemistry for molecular layer deposition of organic and hybrid organic-inorganic polymers”, Acc. Chem. Res. 2009 (doi:10.1021/ar800105q).

Yes. Open it in the LabCanvas editor: all 122 layers are editable, including 4 generated objects (structures, plots, equipment) with their own settings. Change the text, colours and layout, then export PNG, TIFF, SVG or PDF.

Not to view it here. To open and edit it, sign in to LabCanvas or create a free account (the free plan keeps up to 3 designs). Downloading the figure is part of LabCanvas Pro (US$19 a month or US$199 a year).