Mechanism of Thermal Atomic Layer Etch of W Metal Using Sequential Oxidation and Chlorination: A First-Principles Study
Loading...
Access rights
openAccess
publishedVersion
URL
Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
This publication is imported from Aalto University research portal.
View publication in the Research portal (opens in new window)
View/Open full text file from the Research portal (opens in new window)
Other link related to publication (opens in new window)
View publication in the Research portal (opens in new window)
View/Open full text file from the Research portal (opens in new window)
Other link related to publication (opens in new window)
Date
2020-08-12
Major/Subject
Mcode
Degree programme
Language
en
Pages
11
Series
ACS applied materials & interfaces, Volume 12, issue 32, pp. 36670-36680
Abstract
Thermal atomic layer etch (ALE) of W metal can be achieved by sequential self-limiting oxidation and chlorination reactions at elevated temperatures. In this paper, we analyze the reaction mechanisms of W ALE using the first-principles simulation. We show that oxidizing agents such as O2, O3, and N2O can be used to produce a WOx surface layer in the first step of an ALE process with ozone being the most reactive. While the oxidation pulse on clean W is very exergonic, our study suggests that runaway oxidation of W is not thermodynamically favorable. In the second ALE pulse, WCl6 and Cl2 remove the oxidized surface W atoms by the formation of volatile tungsten oxychloride (WxOyClz) species. In this pulse, each adsorbed WCl6 molecule was found to remove one surface W atom with a moderate energy cost. Our calculations further show that the desorption of the additional etch products is endothermic by up to 4.7 eV. Our findings are consistent with the high temperatures needed to produce ALE in experiments. In total, our quantum chemical calculations have identified the lowest energy pathways for ALE of tungsten metal along with the most likely etch products, and these findings may help guide the development of improved etch reagents.Description
Keywords
Atomic layer etching, Atomistic simulations, Density functional theory, First principles, Self-limiting reaction, Transistor contacts
Other note
Citation
Kondati Natarajan, S, Nolan, M, Theofanis, P, Mokhtarzadeh, C & Clendenning, S B 2020, ' Mechanism of Thermal Atomic Layer Etch of W Metal Using Sequential Oxidation and Chlorination : A First-Principles Study ', ACS applied materials & interfaces, vol. 12, no. 32, pp. 36670-36680 . https://doi.org/10.1021/acsami.0c06628