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Ferroelectricity in Ultrathin HfO2-Based Films by Nanosecond Laser Annealing

Athle, Robin LU ; Hill, Megan O. LU ; Irish, Austin LU ; Chen, Huaiyu LU ; Timm, Rainer LU orcid ; Kristensson, Elias LU ; Wallentin, Jesper LU and Borg, Mattias LU orcid (2024) In ACS Applied Materials and Interfaces 16(41).
Abstract

Nonvolatile memory devices based on ferroelectric HfxZr1-xO2 (HZO) show great promise for back-end integrable storage and for neuromorphic accelerators, but their adoption is held back by the inability to scale down the HZO thickness without violating the strict thermal restrictions of the Si CMOS back end of line. In this work, we overcome this challenge and demonstrate the use of nanosecond pulsed laser annealing (NLA) to locally crystallize areas of an ultrathin (3.6 nm) HZO film into the ferroelectric orthorhombic phase. Meanwhile, the heat induced by the pulsed laser is confined to the layers above the Si, allowing for back-end compatible integration. We use a combination of electrical... (More)

Nonvolatile memory devices based on ferroelectric HfxZr1-xO2 (HZO) show great promise for back-end integrable storage and for neuromorphic accelerators, but their adoption is held back by the inability to scale down the HZO thickness without violating the strict thermal restrictions of the Si CMOS back end of line. In this work, we overcome this challenge and demonstrate the use of nanosecond pulsed laser annealing (NLA) to locally crystallize areas of an ultrathin (3.6 nm) HZO film into the ferroelectric orthorhombic phase. Meanwhile, the heat induced by the pulsed laser is confined to the layers above the Si, allowing for back-end compatible integration. We use a combination of electrical characterization, nanofocused scanning X-ray diffraction (nano-XRD), and synchrotron X-ray photoelectron spectroscopy (SXPS) to gain a comprehensive view of the change in material and interface properties by systematically varying both laser energy and the number of laser pulses on the same sample. We find that NLA can provide remanent polarization up to 2Pr= 11.6 μC/cm2 in 3.6 nm HZO, albeit with a significant wake-up effect. The improved TiN/HZO interface observed by XPS explains why device endurance goes beyond 107 cycles, whereas an identical film processed by rapid thermal processing (RTP) breaks already after 106 cycles. All in all, NLA provides a promising approach to scale down the ferroelectric oxide thickness for emerging HZO ferroelectric devices, which is key for their integration in scaled process nodes.

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author
; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
in press
subject
keywords
BEOL compatibility, FeRAM, ferroelectric, hafnium oxide, thin films
in
ACS Applied Materials and Interfaces
volume
16
issue
41
publisher
The American Chemical Society (ACS)
external identifiers
  • pmid:39359120
  • scopus:85206298994
ISSN
1944-8244
DOI
10.1021/acsami.4c10002
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2024 The Authors. Published by American Chemical Society.
id
1a1aaf89-d33f-439b-a932-658d4ac31272
date added to LUP
2024-10-21 09:06:54
date last changed
2024-12-16 15:16:04
@article{1a1aaf89-d33f-439b-a932-658d4ac31272,
  abstract     = {{<p>Nonvolatile memory devices based on ferroelectric Hf<sub>x</sub>Zr<sub>1-x</sub>O<sub>2</sub> (HZO) show great promise for back-end integrable storage and for neuromorphic accelerators, but their adoption is held back by the inability to scale down the HZO thickness without violating the strict thermal restrictions of the Si CMOS back end of line. In this work, we overcome this challenge and demonstrate the use of nanosecond pulsed laser annealing (NLA) to locally crystallize areas of an ultrathin (3.6 nm) HZO film into the ferroelectric orthorhombic phase. Meanwhile, the heat induced by the pulsed laser is confined to the layers above the Si, allowing for back-end compatible integration. We use a combination of electrical characterization, nanofocused scanning X-ray diffraction (nano-XRD), and synchrotron X-ray photoelectron spectroscopy (SXPS) to gain a comprehensive view of the change in material and interface properties by systematically varying both laser energy and the number of laser pulses on the same sample. We find that NLA can provide remanent polarization up to 2P<sub>r</sub>= 11.6 μC/cm<sup>2</sup> in 3.6 nm HZO, albeit with a significant wake-up effect. The improved TiN/HZO interface observed by XPS explains why device endurance goes beyond 10<sup>7</sup> cycles, whereas an identical film processed by rapid thermal processing (RTP) breaks already after 10<sup>6</sup> cycles. All in all, NLA provides a promising approach to scale down the ferroelectric oxide thickness for emerging HZO ferroelectric devices, which is key for their integration in scaled process nodes.</p>}},
  author       = {{Athle, Robin and Hill, Megan O. and Irish, Austin and Chen, Huaiyu and Timm, Rainer and Kristensson, Elias and Wallentin, Jesper and Borg, Mattias}},
  issn         = {{1944-8244}},
  keywords     = {{BEOL compatibility; FeRAM; ferroelectric; hafnium oxide; thin films}},
  language     = {{eng}},
  number       = {{41}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{ACS Applied Materials and Interfaces}},
  title        = {{Ferroelectricity in Ultrathin HfO<sub>2</sub>-Based Films by Nanosecond Laser Annealing}},
  url          = {{http://dx.doi.org/10.1021/acsami.4c10002}},
  doi          = {{10.1021/acsami.4c10002}},
  volume       = {{16}},
  year         = {{2024}},
}