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Title: Molecular Layer Etching of Metalcone Films Using Lithium Organic Salts and Trimethylaluminum

Abstract

Advances in semiconductor device manufacturing are limited by our ability to precisely add and remove thin layers of material in multistep fabrication processes. Recent reports on atomic layer etching (ALE) have provided the means for the precise removal of inorganic thin films deposited by atomic layer deposition (ALD), opening new avenues for nanoscale device design. Here, we report on a new technique for the precise removal of metal organic thin films deposited by molecular layer deposition (MLD), which we term molecular layer etching. This etching process employs sequential exposures of lithium organic salt (LOS) and trimethylaluminum (TMA) precursors to produce self-limiting etching behavior. We employ quartz crystal microbalance experiments to demonstrate (i) etching of alucone films preloaded with LOS upon TMA exposures and (ii) layer-by-layer etching of alucone films using alternating exposures of LOS and TMA. We also identify the selectivity of these etching mechanisms. We probe the mechanism for the layer-by-layer etching of alucone using a quartz crystal microbalance and Fourier transform infrared spectroscopy and identify that the etching proceeds via heterolytic cleaving of Al-O bonds in alucone upon LOS exposure followed by methylation to produce volatile species upon TMA exposure. The etching process results in the removal ofmore » 0.4 nm/cycle of alucone at 160 °C and up to 3.6 nm/cycle of alucone at 266 °C in ex situ etching experiments on silicon wafers. This halogen-free etching process enables etching of MLD films and provides new fabrication pathways for the control of material geometries at the nanoscale.« less

Authors:
ORCiD logo [1];  [2]; ORCiD logo [2];  [2];  [2]; ORCiD logo [2]
  1. Argonne National Lab. (ANL), Argonne, IL (United States). Applied Materials Division; Univ. of Missouri, Columbia, MO (United States)
  2. Argonne National Lab. (ANL), Argonne, IL (United States). Applied Materials Division
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Electrical Energy Storage (CEES); Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1606527
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 32; Journal Issue: 3; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Etching; Thin films; Absorption; Precursors; Atomic layer deposition

Citation Formats

Young, Matthias J., Choudhury, Devika, Letourneau, Steven, Mane, Anil, Yanguas-Gil, Angel, and Elam, Jeffrey W. Molecular Layer Etching of Metalcone Films Using Lithium Organic Salts and Trimethylaluminum. United States: N. p., 2020. Web. https://doi.org/10.1021/acs.chemmater.9b03627.
Young, Matthias J., Choudhury, Devika, Letourneau, Steven, Mane, Anil, Yanguas-Gil, Angel, & Elam, Jeffrey W. Molecular Layer Etching of Metalcone Films Using Lithium Organic Salts and Trimethylaluminum. United States. https://doi.org/10.1021/acs.chemmater.9b03627
Young, Matthias J., Choudhury, Devika, Letourneau, Steven, Mane, Anil, Yanguas-Gil, Angel, and Elam, Jeffrey W. Thu . "Molecular Layer Etching of Metalcone Films Using Lithium Organic Salts and Trimethylaluminum". United States. https://doi.org/10.1021/acs.chemmater.9b03627. https://www.osti.gov/servlets/purl/1606527.
@article{osti_1606527,
title = {Molecular Layer Etching of Metalcone Films Using Lithium Organic Salts and Trimethylaluminum},
author = {Young, Matthias J. and Choudhury, Devika and Letourneau, Steven and Mane, Anil and Yanguas-Gil, Angel and Elam, Jeffrey W.},
abstractNote = {Advances in semiconductor device manufacturing are limited by our ability to precisely add and remove thin layers of material in multistep fabrication processes. Recent reports on atomic layer etching (ALE) have provided the means for the precise removal of inorganic thin films deposited by atomic layer deposition (ALD), opening new avenues for nanoscale device design. Here, we report on a new technique for the precise removal of metal organic thin films deposited by molecular layer deposition (MLD), which we term molecular layer etching. This etching process employs sequential exposures of lithium organic salt (LOS) and trimethylaluminum (TMA) precursors to produce self-limiting etching behavior. We employ quartz crystal microbalance experiments to demonstrate (i) etching of alucone films preloaded with LOS upon TMA exposures and (ii) layer-by-layer etching of alucone films using alternating exposures of LOS and TMA. We also identify the selectivity of these etching mechanisms. We probe the mechanism for the layer-by-layer etching of alucone using a quartz crystal microbalance and Fourier transform infrared spectroscopy and identify that the etching proceeds via heterolytic cleaving of Al-O bonds in alucone upon LOS exposure followed by methylation to produce volatile species upon TMA exposure. The etching process results in the removal of 0.4 nm/cycle of alucone at 160 °C and up to 3.6 nm/cycle of alucone at 266 °C in ex situ etching experiments on silicon wafers. This halogen-free etching process enables etching of MLD films and provides new fabrication pathways for the control of material geometries at the nanoscale.},
doi = {10.1021/acs.chemmater.9b03627},
journal = {Chemistry of Materials},
number = 3,
volume = 32,
place = {United States},
year = {2020},
month = {1}
}

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