Effects of Capping Electrode on Ferroelectric Properties of Hf0.5Zr0.5O2 Thin Films

Cao, Rongrong; Wang, Yan; Zhao, Siqi; Yang, Yang; Zhao, Xiaolong; Wang, Wei; Zhang, Xumeng; Lv, Hangbing; Liu, Qi; Liu, Ming

doi:10.1109/led.2018.2846570

Cited by 166 publications

(135 citation statements)

References 23 publications

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“…[21]. The large Pr is attributed to the low thermal expansions coefficient of IGZO (≈ 4.31×10 -6 /K) [22], because the top electrode with lower thermal expansion coefficient induces large tensile strain in HZO film during rapid thermal process which results in Pr as reported [23]. Metal/HZO/IGZO/metal capacitor has Vc=2V with 15 nm HZO and 8 nm IGZO.…”

Section: Device Fabricationmentioning

confidence: 69%

Low-Voltage Operating Ferroelectric FET with Ultrathin IGZO Channel for High-Density Memory Application

Mo¹,

Tagawa²,

Jin³

et al. 2020

IEEE J. Electron Devices Soc.

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We have fabricated and demonstrated ultrathin In-Ga-Zn-O (IGZO) channel ferroelectric HfO2 field effect transistor (FET) with memory operation. Ultrathin-body IGZO ferroelectric FET (FeFET) shows high mobility and nearly ideal subthreshold slop with minimum 8 nm channel thickness, thanks to the properties of IGZO material, junctionless FET operation, nearly-zero low-k interfacial layer on metal-oxide channel and effective capping for realizing ferroelectric phase formation with HfZrO2 (HZO). The controllable memory operations are achieved with the use of back gate. The design guideline of IGZO FeFET is proposed by discussing the thickness of front gate oxide HZO and back gate oxide SiO2 using TCAD simulation. The material and electrical properties of metal/HZO/IGZO/metal capacitor are also investigated. Metal/HZO/IGZO/metal capacitor has up to 10 8 endurance and over one-year retention. IGZO FeFET shows a potential for high-density and low-power memory application.

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Section: Device Fabricationmentioning

confidence: 69%

Low-Voltage Operating Ferroelectric FET with Ultrathin IGZO Channel for High-Density Memory Application

Mo¹,

Tagawa²,

Jin³

et al. 2020

IEEE J. Electron Devices Soc.

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“…Mechanical stress induced by the W‐capping layer during RTA is believed to be the driving force for the t‐ to o‐phase transition. [ 29 ] In fact, the in‐plane tensile strain, which is developed during the annealing process, substantially suppresses the formation of the m‐phase by preventing the necessary twin deformations required to form the m‐phase. Therefore, the TEC of the capping material substantially alters the structural properties of HZO films.…”

Section: Resultsmentioning

confidence: 99%

“…As a proper capping electrode, tungsten (W) shows the lowest thermal expansion coefficient (TEC) α among the widely used metal electrodes, inducing an in‐plane tensile strain to HZO film during rapid thermal annealing (RTA), which facilitates the formation of the o‐phase. [ 29 ] In‐plane tensile strain stresses on the c‐axis of t‐phase in favor of the phase change from t‐ to o‐phase. Moreover, WO 2 and WO 3 formation enthalpy is almost two times higher than that of HfO 2 and ZrO 2 , preventing the formation of interfacial oxide during the ALD of HZO, which in turn facilitates the deposition of stoichiometric Hf 0.5 Zr 0.5 O 2 by an appropriate tuning of ozone dosage.…”

Section: Introductionmentioning

confidence: 99%

Defect Engineering to Achieve Wake‐up Free HfO₂‐Based Ferroelectrics

Kashir

Hwang

2020

Adv Eng Mater

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Wake‐up effect is still an obstacle in the commercialization of hafnia‐based ferroelectric thin films. Herein, the effect of defects, controlled by ozone dosage, on the field cycling behavior of the atomic layer deposited Hf0.5Zr0.5O2 (HZO) films is investigated. A nearly wake‐up free device is achieved after reduction of carbon contamination and oxygen defects by increasing the ozone dosage. The sample which is grown at 30 s ozone pulse duration shows about 97% of the woken‐up Pr at the pristine state whereas that grown below 5 s ozone pulse time shows a pinched hysteresis loop, that underwent a large wake‐up effect. This behavior is attributed to the increase in oxygen vacancy and carbon concentration in the films deposited at insufficient O3 dosage, which is confirmed by X‐ray photoelectron spectroscopy (XPS). The X‐ray diffraction (XRD) scan shows that the increase in ozone pulse time yields the reduction of tetragonal phase; therefore, the dielectric constant reduces. The I–V measurements reveal the increase in current density as the ozone dosage decreases, which might be due to the generation of oxygen vacancies in the deposited film. Finally, the dynamics of wake‐up effect is investigated, and it appears to be explained well by the Johnson–Mehl–Avrami–Kolmogoroff model, which is based on structural phase transformation.

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“…It was established that metals with relatively low TEC compared with HZO provided additional driving force for t‐ to o‐phase transition during rapid thermal annealing (RTA). [ 34 ] Moreover, suppression of twin deformation through the formation of m‐phase can be substantially prevented. [ 35 ] Another parameter that can affect

f_{\frac{t}{o}}

is the ozone dosage during the atomic layer deposition (ALD) of HfO 2 ‐based thin film.…”

Section: Introductionmentioning

confidence: 99%

Ferroelectric and Dielectric Properties of Hf_0.5Zr_0.5O₂ Thin Film Near Morphotropic Phase Boundary

Kashir

Hwang

2021

Physica Status Solidi (a)

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Since the discovery of ferroelectric (FE) properties in HfO 2 -based materials, [1] numerous advantages, such as simple structures, strong binding energy between oxygen and transition metal ions, large bandgap (%5.3-5.7 eV), and compatibility with current complementary metal-oxide semiconductor technologies, led to extensive research that focused on potential diverse applications, such as FE memory, ferroelectric field-effect transistors (Fe-FETs), pyroelectric sensors, and energy harvesters. Meanwhile, from the material survey of FEs, it is conventional that the structural phase transition induced by a compositional change plays a special role in obtaining excellent piezoelectric and dielectric properties. [2][3][4][5][6][7][8][9] The phase boundary known as morphotropic phase boundary (MPB) separates regions of different symmetries by varying their composition in FEs. [2][3][4][5][6][7][8][9] In fact, when different structural phases are almost degenerated near the MPB, rotations of polarization occur in response to external electric fields instead of a change in the magnitude of polarization. [5] Consequently, materials exhibit maximum piezoelectric and dielectric responses near the MPB, as several phases coexist, and there is nearly no energy barrier separating them. The MPB has garnered significant practical interest, because the variable that drives the transition (i.e., compositions) is inherent. Therefore, it provides an alternative approach to boost the dielectric constant ϵ r without degrading the bandgap. MPB ceramics are the basis of a wide range of piezoelectric and dielectric technologies, such as high-k materials, sensors, actuators, smart systems, ultrasound generation, and sensing and underwater acoustics. These applications motivated researchers to investigate the existence of MPB in the novel promising ceramic compounds, e.g., PbHfO 3 -PbTiO 3 -Pb(Mg 1/3 Nb 2/3 )O 3 , [10,11] lead-free BiFeO 3 -BaTiO 3 , [12,13] Pb(In 1/

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Effects of Capping Electrode on Ferroelectric Properties of Hf_0.5Zr_0.5O₂ Thin Films

Cited by 166 publications

References 23 publications

Low-Voltage Operating Ferroelectric FET with Ultrathin IGZO Channel for High-Density Memory Application

Low-Voltage Operating Ferroelectric FET with Ultrathin IGZO Channel for High-Density Memory Application

Defect Engineering to Achieve Wake‐up Free HfO₂‐Based Ferroelectrics

Ferroelectric and Dielectric Properties of Hf_0.5Zr_0.5O₂ Thin Film Near Morphotropic Phase Boundary

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Effects of Capping Electrode on Ferroelectric Properties of Hf0.5Zr0.5O2 Thin Films

Cited by 166 publications

References 23 publications

Low-Voltage Operating Ferroelectric FET with Ultrathin IGZO Channel for High-Density Memory Application

Low-Voltage Operating Ferroelectric FET with Ultrathin IGZO Channel for High-Density Memory Application

Defect Engineering to Achieve Wake‐up Free HfO2‐Based Ferroelectrics

Ferroelectric and Dielectric Properties of Hf0.5Zr0.5O2 Thin Film Near Morphotropic Phase Boundary

Contact Info

Product

Resources

About

Effects of Capping Electrode on Ferroelectric Properties of Hf_0.5Zr_0.5O₂ Thin Films

Defect Engineering to Achieve Wake‐up Free HfO₂‐Based Ferroelectrics

Ferroelectric and Dielectric Properties of Hf_0.5Zr_0.5O₂ Thin Film Near Morphotropic Phase Boundary