The etching of HfO and ZrO high-k dielectrics is studied using plasma enhanced atomic layer etching. The etching method relies on a continuous argon inductively coupled plasma discharge in which reactive gases are pulsed, followed by substrate biasing; both steps are separated by purge periods. It is found that pure BCl is too chemically active while a Cl–BCl allows a high process synergy; in addition, the latter gives a high selectivity to SiO. The optimal etch conditions are applied to high-k layers deposited on top of WS transition metal dichalcogenide. Postetch analysis shows negligible tungsten and sulfur depletion as well as negligible change in optical (Raman) response of the 2D layer, indicating that atomic layer etching concepts allows us to prevent WS material loss or damage.
Plasma enhanced atomic layer etching of high-k layers on WS2
Note: This paper is part of the 2023 Special Topic Collection on Atomic Layer Etching (ALE).
J.-F. de Marneffe, D. Marinov, A. Goodyear, P.-J. Wyndaele, N. St. J. Braithwaite, S. Kundu, I. Asselberghs, M. Cooke, S. De Gendt; Plasma enhanced atomic layer etching of high-k layers on WS2. J. Vac. Sci. Technol. A 1 July 2022; 40 (4): 042602. https://doi.org/10.1116/6.0001726
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