This work complements our previous manuscript [J. Vac. Sci. Technol. A 41, 062602 (2023)] where predictions from molecular dynamics (MD) simulations of silicon–chlorine–argon (Si–Cl –Ar) atomic layer etching (ALE) are compared to experiments. When etch product distributions for atomic chlorine (Cl) and silicon chlorides were initially compared to optical emission spectroscopy (OES) signals, it appeared that there was a discrepancy between the MD predictions and experimental results at higher ion fluences. Experiments showed a relatively long period of nearly constant Cl-containing etch products released from the ion-bombarded surface (referred to as the “plateau”) but this effect was not observed in MD simulations. In this report, we demonstrate that the “plateau” observed in the OES signals is most likely due to the desorption of Cl-containing etch products from the walls of the reactor and subsequent adsorption on the Si substrate. Experiments varying the gas residence time in the chamber while keeping incoming gas concentrations and pressure constant support this interpretation. We also conducted experiments with an additional Ar-only flow in the chamber to reduce the concentration of Cl-containing species on the chamber walls. For both sets of flow modification experiments, we observe results consistent with the hypothesis that Cl-containing species desorbing from chamber walls are a significant cause of the observed discrepancy between MD predictions and experimental observations. If the measured OES signals are corrected for this “additional” source of Cl-containing species at the surface, the MD predictions and measured OES signals are in excellent agreement. This further supports the predictive capability of MD simulations to accurately capture the relevant physical and chemical processes in plasma-assisted ALE processes. We provide an order of magnitude estimate of the required density of Cl-containing species that would account for the additional etch products observed. Finally, we discuss the implications of this effect on ALE in plasma nanofabrication.
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July 2024
Research Article|
June 12 2024
Reactor wall effects in Si–Cl2–Ar atomic layer etching
Special Collection:
Atomic Layer Etching (ALE)
Joseph R. Vella
;
Joseph R. Vella
(Conceptualization, Formal analysis, Investigation, Methodology, Validation, Writing – original draft, Writing – review & editing)
1
Princeton Plasma Physics Laboratory
, Princeton, New Jersey 08540
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Mahmoud A. I. Elgarhy
;
Mahmoud A. I. Elgarhy
(Data curation, Formal analysis, Investigation, Methodology, Visualization)
2
William A. Brookshire Department of Chemical and Biomolecular Engineering, University of Houston
, Houston, Texas 772043
Physics Department, Faculty of Science, Al-Azhar University
, Cairo 11651, Egypt
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Qinzhen Hao
;
Qinzhen Hao
(Data curation, Formal analysis, Investigation, Methodology, Visualization)
2
William A. Brookshire Department of Chemical and Biomolecular Engineering, University of Houston
, Houston, Texas 77204
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Vincent M. Donnelly
;
Vincent M. Donnelly
(Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Supervision, Validation, Writing – review & editing)
2
William A. Brookshire Department of Chemical and Biomolecular Engineering, University of Houston
, Houston, Texas 77204
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David B. Graves
David B. Graves
a)
(Conceptualization, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Validation, Writing – original draft, Writing – review & editing)
1
Princeton Plasma Physics Laboratory
, Princeton, New Jersey 085404
Department of Chemical and Biological Engineering, Princeton University
, Princeton, New Jersey 08540a)Author to whom correspondence should be addressed: [email protected]
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a)Author to whom correspondence should be addressed: [email protected]
J. Vac. Sci. Technol. A 42, 042604 (2024)
Article history
Received:
March 26 2024
Accepted:
May 24 2024
Citation
Joseph R. Vella, Mahmoud A. I. Elgarhy, Qinzhen Hao, Vincent M. Donnelly, David B. Graves; Reactor wall effects in Si–Cl2–Ar atomic layer etching. J. Vac. Sci. Technol. A 1 July 2024; 42 (4): 042604. https://doi.org/10.1116/6.0003651
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