Ferroelectric Switching in Trilayer Al2O3/HfZrOx/Al2O3 Structure

Im, Solyee; Kang, Seok Hun; Kim, Yeriaron; Kim, Jeong Hun; Im, Jooyoung; Yoon, Sung‐Min; Moon, Seoksu; Woo, Jiyong

doi:10.3390/mi11100910

Cited by 8 publications

(2 citation statements)

References 38 publications

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“…Factors that may explain the improved endurance with the inclusion of Al 2 O 3 into HZO capacitors include (1) the reduction of interface trapped charge and (2) a decrease in oxygen-related defects. Several studies have suggested that the reduction of leakage current density in HfO 2 -based devices with the inclusion of an alumina buffer layer stems from how the Al 2 O 3 layer interacts with oxygen defects in HZO [52,60,61]. It is well-known that TiO x forms at the TiN/HZO interface where oxygen diffuses from the HZO layer to the oxide-electrode and reacts with metallic Ti [29,52].…”

Section: Resultsmentioning

confidence: 99%

Reduced fatigue and leakage of ferroelectric TiN/Hf_0.5Zr_0.5O₂/TiN capacitors by thin alumina interlayers at the top or bottom interface

Hsain¹,

Lee²,

Lancaster³

et al. 2023

Nanotechnology

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Hf0.5Zr0.5O2 (HZO) thin films are promising candidates for non-volatile memory and other related applications due to their demonstrated ferroelectricity at the nanoscale and compatibility with Si processing. However, one reason that HZO has not been fully scaled into industrial applications is due to its deleterious wake-up and fatigue behavior which leads to an inconsistent remanent polarization during cycling. In this study, we explore an interfacial engineering strategy in which we insert 1-nm Al2O3 interlayers at either the top or bottom HZO/TiN interface of sequentially deposited metal-ferroelectric-metal capacitors. By inserting an interfacial layer while limiting exposure to the ambient environment, we successfully introduce a protective passivating layer of Al2O3 that provides excess oxygen to mitigate vacancy formation at the interface. We report that TiN/HZO/TiN capacitors with a 1-nm Al2O3 at the top interface demonstrate a higher remanent polarization (2Pr ~ 42 µC/cm2) and endurance limit beyond 108 cycles at a cycling field amplitude of 3.5 MV/cm. We use time-of-flight secondary ion mass spectrometry (ToF-SIMS), energy dispersive spectroscopy (EDS), and grazing incidence x-ray diffraction (GIXRD) to elucidate the origin of enhanced endurance and leakage properties in capacitors with an inserted 1-nm Al2O3 layer. We demonstrate that the use of Al2O3 as a passivating dielectric, coupled with sequential ALD fabrication, is an effective means of interfacial engineering and enhances the performance of ferroelectric HZO devices.

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Section: Resultsmentioning

confidence: 99%

Reduced fatigue and leakage of ferroelectric TiN/Hf_0.5Zr_0.5O₂/TiN capacitors by thin alumina interlayers at the top or bottom interface

Hsain¹,

Lee²,

Lancaster³

et al. 2023

Nanotechnology

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“…4. The achieved Pr of about 10 μC/cm 2 seemed to be observed, but the transition around the Vc occurred slowly [22]. These results were related not only to polarization induced electrons, but also to leakage induced charges, allowing more currents to be included at the large voltage regime.…”

Section: B Trilayer Structure With Alo/hzo/alomentioning

confidence: 92%

Device Engineering Strategy of Zr-Doped HfOx Ferroelectric Memory for Unconventional Computing Applications

Woo

2021

2021 IEEE International Symposium on Circuits and Systems (ISCAS)

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This study reports the device design strategy of ferroelectric memory based on Zr doped HfOx for memory and neuromorphic computing systems. It has been believed that polarization switching occurs due to the transformation in the HfOx layer to a specific crystalline phase through high temperature annealing. Considering the essentially required fabrication process, ferroelectric memory available in various configurations may be thermally stable or need to be demonstrated at as low a temperature as possible. Therefore, in this paper, device design and engineering strategies to improve the polarization switching are addressed. First, the experimental results show that a high pressure annealing technique not only significantly lowers the temperature required for phase transition in the HfOx layer to550 o C, but also enhances the crystallinity. On the other hand, in a situation where the polarization is utilized to adjust the carrier density of the transistor channel, thermally stabilized ferroelectricity at high temperatures is preferred. A trilayer structure in which thin Al2O3 layer is introduced to improve instability is also discussed.

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Polarization switching in Hf0.5Zr0.5O2-dielectric stack: The role of dielectric layer thickness

Saha

et al. 2021

Applied Physics Letters

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We investigate the polarization switching mechanism in ferroelectric-dielectric (FE-DE) stacks and its dependence on the dielectric thickness (TDE). We fabricate HZO-Al2O3 (FE-DE) stack and experimentally demonstrate a decrease in remnant polarization and an increase in coercive voltage of the FE-DE stack with an increase in TDE. Using phase-field simulations, we show that an increase in TDE results in a larger number of reverse domains in the FE layer to suppress the depolarization field, which leads to a decrease in remanent polarization and an increase in coercive voltage. Further, the applied voltagedriven polarization switching suggests domain-nucleation dominant characteristics for low TDE, and domain-wall motioninduced behavior for higher TDE. In addition, we show that the hysteretic charge-voltage characteristics of the FE layer in the FE-DE stack exhibit a negative slope region due to the multi-domain polarization switching in the FE layer. Based on our analysis, the trends in charge-voltage characteristics of the FE-DE stack with respect to different TDE (which are out of the scope of single-domain models) can be described well with multi-domain polarization switching mechanisms.Ferroelectric (FE) hafnium oxide, by virtue of its CMOS process compatibility 1,2 and rich domain dynamics 3,4 , has been identified as one of the most promising candidates for enabling future electronic devices. By integrating doped HfO 2 (as FE) in the gate stack of a transistor (FE-FET), non-volatile memory (NVM) 5-6 , neuron 7 and synaptic 8,9 functionalities have been demonstrated. Such diverse functionalities demand different characteristics of polarization (P) switching in the FE layer. For example, an abrupt P-switching is beneficial for neurons and binary NVMs, while a gradual P-switching is favorable for multi-bit memories and synapses. Therefore, it becomes essential to appropriately design FEFET for application-specific device behavior, for which gate stack optimization plays a key role.

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Ferroelectric Switching in Trilayer Al2O3/HfZrOx/Al2O3 Structure

Cited by 8 publications

References 38 publications

Reduced fatigue and leakage of ferroelectric TiN/Hf_0.5Zr_0.5O₂/TiN capacitors by thin alumina interlayers at the top or bottom interface

Reduced fatigue and leakage of ferroelectric TiN/Hf_0.5Zr_0.5O₂/TiN capacitors by thin alumina interlayers at the top or bottom interface

Device Engineering Strategy of Zr-Doped HfOx Ferroelectric Memory for Unconventional Computing Applications

Polarization switching in Hf0.5Zr0.5O2-dielectric stack: The role of dielectric layer thickness

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Ferroelectric Switching in Trilayer Al2O3/HfZrOx/Al2O3 Structure

Cited by 8 publications

References 38 publications

Reduced fatigue and leakage of ferroelectric TiN/Hf0.5Zr0.5O2/TiN capacitors by thin alumina interlayers at the top or bottom interface

Reduced fatigue and leakage of ferroelectric TiN/Hf0.5Zr0.5O2/TiN capacitors by thin alumina interlayers at the top or bottom interface

Device Engineering Strategy of Zr-Doped HfOx Ferroelectric Memory for Unconventional Computing Applications

Polarization switching in Hf0.5Zr0.5O2-dielectric stack: The role of dielectric layer thickness

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Product

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Reduced fatigue and leakage of ferroelectric TiN/Hf_0.5Zr_0.5O₂/TiN capacitors by thin alumina interlayers at the top or bottom interface

Reduced fatigue and leakage of ferroelectric TiN/Hf_0.5Zr_0.5O₂/TiN capacitors by thin alumina interlayers at the top or bottom interface