Simulation of conformality of ALD growth inside lateral channels: comparison between a diffusion-reaction model and a ballistic transport-reaction model

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Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2023-09-14
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Language
en
Pages
13
22952-22964
Series
Physical Chemistry Chemical Physics, Volume 25, issue 34
Abstract
Atomic layer deposition (ALD) has found significant use in the coating of high-aspect-ratio (HAR) structures. Approaches to model ALD film conformality in HAR structures can generally be classified into diffusion-reaction (DR) models, ballistic transport-reaction (BTR) models and Monte Carlo simulations. This work compares saturation profiles obtained using a DR model and a BTR model. The saturation profiles were compared qualitatively and quantitatively in terms of half-coverage penetration depth, slope at half-coverage penetration depth and adsorption front broadness. The results showed qualitative agreement between the models, except for a section of elevated surface coverage at the end of the structure, ‘trunk’, observed in the BTR model. Quantitatively, the BTR model produced deeper penetration into the structure, lower absolute values of the slope at half-coverage penetration depth and broader adsorption fronts compared to the DR model. These differences affect the values obtained when extracting kinetic parameters from the saturation profiles.
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Funding Information: The work was financially supported by the Academy of Finland (ALDI consortium, decision no. 331082 and COOLCAT consortium, decision no. 329978) and by Prof. Puurunen's starting grant at Aalto University. Emma Verkama implemented the Ylilammi et al.12 diffusion–reaction model as a MATLAB script.31 Aleksi Heikkinen initiated the use of the ballistic transport–reaction model by Yanguas-Gil and Elam10,32 as a summer student in Puurunen's research group. Angel Yanguas-Gil's help in getting the group started with Machball is gratefully acknowledged; likewise is Andreas Werbrouck's peer feedback on the submitted preprint. J. J. thanks Aada Illikainen for the discussions on mathematical notation conventions. This work was presented as a talk at the AVS 23rd International Conference on Atomic Layer Deposition (ALD 2023) in Bellevue, Washington, Jul 23–26, 2023. Earlier versions of this work have been presented as a talk at the ALD 2021 conference (online) by Yim et al.46 and as a poster at the ALD 2022 conference, Belgium, by Velasco et al.47 We acknowledge the computational resources provided by the Aalto Science-IT project. Publisher Copyright: © 2023 The Royal Society of Chemistry.
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Järvilehto, J, Velasco, J A, Yim, J, Gonsalves, C & Puurunen, R L 2023, ' Simulation of conformality of ALD growth inside lateral channels: comparison between a diffusion-reaction model and a ballistic transport-reaction model ', Physical Chemistry Chemical Physics, vol. 25, no. 34, pp. 22952-22964 . https://doi.org/10.1039/d3cp01829f