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Top Electrode Engineering for Freedom in Design and Implementation of Ferroelectric Tunnel Junctions Based on Hf1- xZrxO2

Athle, Robin LU ; Persson, Anton E.O. LU orcid ; Troian, Andrea LU and Borg, Mattias LU orcid (2022) In ACS Applied Electronic Materials 4(3). p.1002-1009
Abstract

Ferroelectric tunnel junctions (FTJs) based on ultrathin HfO2 have great potential as a fast and energy-efficient memory technology compatible with complementary metal oxide semiconductors. FTJs consist of a ferroelectric film sandwiched between two distinct electrodes, the properties of which are intricately linked to the electrical properties of the FTJs. Here we utilize a W crystallization electrode (CE) to achieve a high and reproducible remanent polarization, combined with a metal replacement process in which the W is carefully removed and replaced by another top electrode (TE). In this way we separate the ferroelectric film properties from the device design and can thereby evaluate the effect of the TE work function (WF) and... (More)

Ferroelectric tunnel junctions (FTJs) based on ultrathin HfO2 have great potential as a fast and energy-efficient memory technology compatible with complementary metal oxide semiconductors. FTJs consist of a ferroelectric film sandwiched between two distinct electrodes, the properties of which are intricately linked to the electrical properties of the FTJs. Here we utilize a W crystallization electrode (CE) to achieve a high and reproducible remanent polarization, combined with a metal replacement process in which the W is carefully removed and replaced by another top electrode (TE). In this way we separate the ferroelectric film properties from the device design and can thereby evaluate the effect of the TE work function (WF) and conduction band electron density (ne) on the tunneling electroresistance (TER) and device reliability. We compare FTJs designed with a TiN bottom electrode and W, Cr, or Ni TE and find that the use of high electron density metals such as Ni or Cr as TE allows for an improved TER, albeit at the cost of reliability due to a large built-in electric field. To bypass this effect, a bilayer Cr/Ni TE is implemented, which allows for a high TER and minimal built-in field, leading to excellent retention and endurance beyond 108 cycles. The results presented here thus highlight a process flow for reliable design and implementation of FTJs.

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Please use this url to cite or link to this publication:
author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
ferroelectric tunnel junction, hafnium oxide, thin films, tunneling electroresistance, work function
in
ACS Applied Electronic Materials
volume
4
issue
3
pages
1002 - 1009
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:85125323803
ISSN
2637-6113
DOI
10.1021/acsaelm.1c01181
project
Ultra-fast thermal processing for next-generation ferroelectric hafnia
Development and Implementation of Ferroelectric oxides
language
English
LU publication?
yes
additional info
Funding Information: This work was supported financially by the Swedish Research Council (VR) grant nos. 2018-05379, 2016-6186, 2017-4108, along with the NanoLund Centre for Nanoscience at Lund University. Publisher Copyright: © 2021 ACS Applied Electronic Materials. All right reserved.
id
01c1250e-d2a8-4bbe-9ad8-d55a309bf7ac
date added to LUP
2022-03-10 11:42:45
date last changed
2024-02-01 20:11:35
@article{01c1250e-d2a8-4bbe-9ad8-d55a309bf7ac,
  abstract     = {{<p>Ferroelectric tunnel junctions (FTJs) based on ultrathin HfO2 have great potential as a fast and energy-efficient memory technology compatible with complementary metal oxide semiconductors. FTJs consist of a ferroelectric film sandwiched between two distinct electrodes, the properties of which are intricately linked to the electrical properties of the FTJs. Here we utilize a W crystallization electrode (CE) to achieve a high and reproducible remanent polarization, combined with a metal replacement process in which the W is carefully removed and replaced by another top electrode (TE). In this way we separate the ferroelectric film properties from the device design and can thereby evaluate the effect of the TE work function (WF) and conduction band electron density (ne) on the tunneling electroresistance (TER) and device reliability. We compare FTJs designed with a TiN bottom electrode and W, Cr, or Ni TE and find that the use of high electron density metals such as Ni or Cr as TE allows for an improved TER, albeit at the cost of reliability due to a large built-in electric field. To bypass this effect, a bilayer Cr/Ni TE is implemented, which allows for a high TER and minimal built-in field, leading to excellent retention and endurance beyond 108 cycles. The results presented here thus highlight a process flow for reliable design and implementation of FTJs.</p>}},
  author       = {{Athle, Robin and Persson, Anton E.O. and Troian, Andrea and Borg, Mattias}},
  issn         = {{2637-6113}},
  keywords     = {{ferroelectric tunnel junction; hafnium oxide; thin films; tunneling electroresistance; work function}},
  language     = {{eng}},
  number       = {{3}},
  pages        = {{1002--1009}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{ACS Applied Electronic Materials}},
  title        = {{Top Electrode Engineering for Freedom in Design and Implementation of Ferroelectric Tunnel Junctions Based on Hf<sub>1- x</sub>Zr<sub>x</sub>O<sub>2</sub>}},
  url          = {{http://dx.doi.org/10.1021/acsaelm.1c01181}},
  doi          = {{10.1021/acsaelm.1c01181}},
  volume       = {{4}},
  year         = {{2022}},
}