Enhancing ferroelectric properties of Hf0.5Zr0.5O2 thin films using the HfN/TiN and W/TiN bi-layer bottom electrodes

This study clarifies the influence of single-layer (TiN, HfN, W) and bi-layer (HfN/TiN, W/TiN) bottom electrodes (BEs) on the ferroelectric performance and reliability of the 10-nm-thick Hf0.5Zr0.5O2 (HZO) thin films. A smaller thermal expansion coefficient in HfN or W imposes higher in-plane tensil...

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Main Authors: Han Sol Park, Joong Chan Shin, Kyung Do Kim, Seong Jae Shin, Jae Hee Song, Seung Kyu Ryoo, In Soo Lee, Suk Hyun Lee, Hyunwoo Nam, Cheol Seong Hwang
Format: Article
Language:English
Published: Elsevier 2025-11-01
Series:Journal of Materiomics
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Online Access:http://www.sciencedirect.com/science/article/pii/S2352847825000991
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author Han Sol Park
Joong Chan Shin
Kyung Do Kim
Seong Jae Shin
Jae Hee Song
Seung Kyu Ryoo
In Soo Lee
Suk Hyun Lee
Hyunwoo Nam
Cheol Seong Hwang
author_facet Han Sol Park
Joong Chan Shin
Kyung Do Kim
Seong Jae Shin
Jae Hee Song
Seung Kyu Ryoo
In Soo Lee
Suk Hyun Lee
Hyunwoo Nam
Cheol Seong Hwang
author_sort Han Sol Park
collection DOAJ
description This study clarifies the influence of single-layer (TiN, HfN, W) and bi-layer (HfN/TiN, W/TiN) bottom electrodes (BEs) on the ferroelectric performance and reliability of the 10-nm-thick Hf0.5Zr0.5O2 (HZO) thin films. A smaller thermal expansion coefficient in HfN or W imposes higher in-plane tensile stress on the HZO thin films, facilitating the polar orthorhombic (o-) phase fraction and enhancing remanent polarization (Pr). However, thicker interfacial layers formed when HfN or W single-layer BE and HZO contacted directly, leading to excessive leakage current and degraded ferroelectric performance. These excessive interfacial layers were effectively suppressed by inserting a thin (5 nm–20 nm) TiN layer on the HfN or W BEs. As a result, the HZO thin films on the HfN/TiN and W/TiN bi-layer BEs decrease the HZO grain size, facilitating the o-phase formation (increasing Pr) and lowering the film's coercive field. However, the higher surface roughness of the W/TiN bi-layer BEs induced excessive leakage current and reliability degradation. In contrast, the HfN BEs with a 10- or 20-nm-thick upper TiN layer lower the surface roughness of the BEs, thereby eliminating the adverse effects. As a result, the HfN 40 nm/TiN 10 nm/HZO/TiN stack exhibited enhanced ferroelectric performance up to 109 switching cycles with a lower cycling field of 2.7 MV/cm than the TiN 50 nm/HZO/TiN stack with a cycling field of 3.7 MV/cm.
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spelling doaj-art-4ec4adbfdffa46f98a0357189450e5702025-08-23T04:48:43ZengElsevierJournal of Materiomics2352-84782025-11-0111610110910.1016/j.jmat.2025.101109Enhancing ferroelectric properties of Hf0.5Zr0.5O2 thin films using the HfN/TiN and W/TiN bi-layer bottom electrodesHan Sol Park0Joong Chan Shin1Kyung Do Kim2Seong Jae Shin3Jae Hee Song4Seung Kyu Ryoo5In Soo Lee6Suk Hyun Lee7Hyunwoo Nam8Cheol Seong Hwang9Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, College of Engineering, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul, 08826, Republic of KoreaDepartment of Materials Science and Engineering and Inter-University Semiconductor Research Center, College of Engineering, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul, 08826, Republic of KoreaDepartment of Materials Science and Engineering and Inter-University Semiconductor Research Center, College of Engineering, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul, 08826, Republic of KoreaDepartment of Materials Science and Engineering and Inter-University Semiconductor Research Center, College of Engineering, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul, 08826, Republic of KoreaDepartment of Materials Science and Engineering and Inter-University Semiconductor Research Center, College of Engineering, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul, 08826, Republic of KoreaDepartment of Materials Science and Engineering and Inter-University Semiconductor Research Center, College of Engineering, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul, 08826, Republic of KoreaDepartment of Materials Science and Engineering and Inter-University Semiconductor Research Center, College of Engineering, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul, 08826, Republic of KoreaDepartment of Materials Science and Engineering and Inter-University Semiconductor Research Center, College of Engineering, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul, 08826, Republic of KoreaDepartment of Materials Science and Engineering and Inter-University Semiconductor Research Center, College of Engineering, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul, 08826, Republic of KoreaCorresponding author.; Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, College of Engineering, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul, 08826, Republic of KoreaThis study clarifies the influence of single-layer (TiN, HfN, W) and bi-layer (HfN/TiN, W/TiN) bottom electrodes (BEs) on the ferroelectric performance and reliability of the 10-nm-thick Hf0.5Zr0.5O2 (HZO) thin films. A smaller thermal expansion coefficient in HfN or W imposes higher in-plane tensile stress on the HZO thin films, facilitating the polar orthorhombic (o-) phase fraction and enhancing remanent polarization (Pr). However, thicker interfacial layers formed when HfN or W single-layer BE and HZO contacted directly, leading to excessive leakage current and degraded ferroelectric performance. These excessive interfacial layers were effectively suppressed by inserting a thin (5 nm–20 nm) TiN layer on the HfN or W BEs. As a result, the HZO thin films on the HfN/TiN and W/TiN bi-layer BEs decrease the HZO grain size, facilitating the o-phase formation (increasing Pr) and lowering the film's coercive field. However, the higher surface roughness of the W/TiN bi-layer BEs induced excessive leakage current and reliability degradation. In contrast, the HfN BEs with a 10- or 20-nm-thick upper TiN layer lower the surface roughness of the BEs, thereby eliminating the adverse effects. As a result, the HfN 40 nm/TiN 10 nm/HZO/TiN stack exhibited enhanced ferroelectric performance up to 109 switching cycles with a lower cycling field of 2.7 MV/cm than the TiN 50 nm/HZO/TiN stack with a cycling field of 3.7 MV/cm.http://www.sciencedirect.com/science/article/pii/S2352847825000991FerroelectricHf0.5Zr0.5O2Coefficient of thermal expansionTensile stressBi-layer bottom electrode
spellingShingle Han Sol Park
Joong Chan Shin
Kyung Do Kim
Seong Jae Shin
Jae Hee Song
Seung Kyu Ryoo
In Soo Lee
Suk Hyun Lee
Hyunwoo Nam
Cheol Seong Hwang
Enhancing ferroelectric properties of Hf0.5Zr0.5O2 thin films using the HfN/TiN and W/TiN bi-layer bottom electrodes
Journal of Materiomics
Ferroelectric
Hf0.5Zr0.5O2
Coefficient of thermal expansion
Tensile stress
Bi-layer bottom electrode
title Enhancing ferroelectric properties of Hf0.5Zr0.5O2 thin films using the HfN/TiN and W/TiN bi-layer bottom electrodes
title_full Enhancing ferroelectric properties of Hf0.5Zr0.5O2 thin films using the HfN/TiN and W/TiN bi-layer bottom electrodes
title_fullStr Enhancing ferroelectric properties of Hf0.5Zr0.5O2 thin films using the HfN/TiN and W/TiN bi-layer bottom electrodes
title_full_unstemmed Enhancing ferroelectric properties of Hf0.5Zr0.5O2 thin films using the HfN/TiN and W/TiN bi-layer bottom electrodes
title_short Enhancing ferroelectric properties of Hf0.5Zr0.5O2 thin films using the HfN/TiN and W/TiN bi-layer bottom electrodes
title_sort enhancing ferroelectric properties of hf0 5zr0 5o2 thin films using the hfn tin and w tin bi layer bottom electrodes
topic Ferroelectric
Hf0.5Zr0.5O2
Coefficient of thermal expansion
Tensile stress
Bi-layer bottom electrode
url http://www.sciencedirect.com/science/article/pii/S2352847825000991
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