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In silico design of a thermal atomic layer etch process of cobalt
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Date
2021-03-03
Authors
Kondati Natarajan, Suresh
Nolan, Michael
Theofanis, Patrick
Mokhtarzadeh, Charles
Clendenning, Scott B.
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Volume Title
Publisher
American Institute of Physics
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Abstract
Thermal atomic layer etch (ALE), facilitating the removal of up to one monolayer of material per cycle, is growing in importance for thin-film processing. The number of available ALE processes is much smaller than for atomic layer deposition, its complementary growth process. Quantum chemical simulations are a key approach in the development of new thermal ALE processes, however, methodologies and workflows need to be developed. In this regard, the present paper reports a simulation-based approach toward the development of new thermal ALE processes using metallic cobalt as a test case. We demonstrate a predictive process discovery approach for ALE in which target volatile etch products and the corresponding gas phase reactants are chosen from the literature, an overall ALE cycle for each combination of reactant is investigated for thermochemical favorability, and the detailed mechanisms of the individual reaction steps in the proposed ALE processes are studied using density functional theory. From these results, we derive a temperature-pressure process window for each combination of reactants at typical reactant and product pressures allowing the selection of an ALE process window. For Co ALE, we investigated propene, butyne, silane, and trimethyl silane as a first pulse reactant and CO as the second pulse reactant. We propose propene and CO as the best combination of reactants for Co ALE. Propene adsorbs with sufficient strength to the target Co atom at temperatures below the CO decomposition temperature of 440 K, which results in the lowest energy etch species. This approach is equally relevant for the ALE process design of elemental, binary, and ternary materials.
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Keywords
Thermal atomic layer etch (ALE) , Thin-film processing , Quantum chemical simulations
Citation
Kondati Natarajan, S., Nolan, M., Theofanis, P., Mokhtarzadeh, C. and Clendenning, S. B. (2021) 'In silico design of a thermal atomic layer etch process of cobalt', Journal of Vacuum Science and Technology A, 39(2), 022603 (12pp). doi: 10.1116/6.0000804
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© 2021, the Authors. Published under license by AIP Publishing. This article may be downloaded for personal use only. Any other use requires prior permission of the author(s) and AIP Publishing. This article appeared as: Kondati Natarajan, S., Nolan, M., Theofanis, P., Mokhtarzadeh, C. and Clendenning, S. B. (2021) 'In silico design of a thermal atomic layer etch process of cobalt', Journal of Vacuum Science and Technology A, 39(2), 022603 (12pp), doi: 10.1116/6.0000804, and may be found at https://doi.org/10.1116/6.0000804