Plasma enhanced atomic layer etching of high-k layers on WS₂

de Marneffe, J-F; Marinov, D; Goodyear, A; Wyndaele, P-J; Braithwaite, N StJ; Kundu, S; Cooke, MJ and De Gendt, S (2022). Plasma enhanced atomic layer etching of high-k layers on WS₂. Journal of Vacuum Science & Technology A, 40(4)

DOI: https://doi.org/10.1116/6.0001726

Abstract

The etching of HfO₂ and ZrO₂ 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 BCl3 is too chemically active while a Cl_2- BCl₃ allows a high process synergy; in addition the latter gives a high selectivity to SiO₂. The optimal etch conditions are applied to high-k layers deposited on top of WS₂ transition metal dichalcogenide. Post-etch analysis show 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 to prevent WS₂ material loss or damage.

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About

• Item ORO ID
• 83411
• Item Type
• Journal Item
• Keywords
• ‘Plasma processing’; ‘atomic layer etching’; ALE; high-k dielectric
• Academic Unit or School
• Faculty of Science, Technology, Engineering and Mathematics (STEM)
• Research Group
• Physics
• Copyright Holders
• © 2022 Authors
• Depositing User
• N St.J Braithwaite