Ferroelectric properties and switching endurance of Hf0.5Zr0.5O2 films on TiN bottom and TiN or RuO2 top electrodes

Park, Min Hyuk; Kim, Han Joon; Kim, Yu Jin; Jeon, Woojin; Moon, Taehwan; Hwang, Cheol Seong

doi:10.1002/pssr.201409017

Cited by 135 publications

(117 citation statements)

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“…10 The increase in E c in the O 2 -annealed sample, which can occur with the oxidation of TiN electrodes, was not observed too. 13 From the comparison of Fig. 3a and b, the increase in the P r and E c of HZO films can be observed by the wake-up cycling.…”

Section: Resultsmentioning

confidence: 84%

Study on the internal field and conduction mechanism of atomic layer deposited ferroelectric Hf_0.5Zr_0.5O₂ thin films

Park

Kim

et al. 2015

J. Mater. Chem. C

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The internal field (E int ) in ferroelectric films is an important factor which can affect the reliability of practical devices utilizing two memory states which results from the remanent polarizations of ferroelectric films. In the current work, the E int in TiN/Hf 0.5 Zr 0.5 O 2 /TiN capacitors was controlled by changing the annealing atmosphere (N 2 , O 2 , and forming gas). The magnitude of negative E int in O 2 -annealed samples was the largest, whereas that in the forming gas-annealed sample was the smallest. The magnitude of E int can be understood based on the asymmetric distribution of oxygen vacancies near top and bottom TiN electrodes. Despite the large magnitude of E int , the two remanent polarizations can be reliably retained due to the large coercive electric field of Hf 0.5 Zr 0.5 O 2 films, and this is expected to be beneficial for application in semiconductor memory devices. During the repetitive electric field cycling for the wake-up process, the change in E int in O 2 -and forming gas-annealed samples showed the opposite tendency: the magnitude of E int in the O 2 -annealed Hf 0.5 Zr 0.5 O 2 film decreased, whereas that in the forming gas-annealed film increased. This difference is believed to be due to the redistribution of oxygen vacancies with electric field high enough for the migration of oxygen vacancies. The conduction mechanism of electrons through Hf 0.5 Zr 0.5 O 2 films was also examined, and the results fitted best with the Poole-Frenkel emission model with the shallow traps for all the samples with a reasonable optical dielectric constant value for Hf 0.5 Zr 0.5 O 2 .

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Section: Resultsmentioning

confidence: 84%

Study on the internal field and conduction mechanism of atomic layer deposited ferroelectric Hf_0.5Zr_0.5O₂ thin films

Park

Kim

et al. 2015

J. Mater. Chem. C

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“…Studies by Park et al even suggest a partial oxidation of the complete TiN. [41,42] Thus, the complete device stack consists of TiO x N y /TM-HfO x /FE-HfO 2 /TM-HfO x /TiO x sandwiched between two TiN electrodes, Figure 5b. Polycrystallinity of the HfO 2 layer was explicitly taken into account, creating the grain structure of the stack, as shown in Figure 5b.…”

Section: Modelingmentioning

confidence: 97%

Physical Mechanisms behind the Field‐Cycling Behavior of HfO₂‐Based Ferroelectric Capacitors

Pešić

Fengler

Larcher

et al. 2016

Adv Funct Materials

705

461

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Novel hafnium oxide (HfO 2 )-based ferroelectrics reveal full scalability and complementary metal oxide semiconductor integratability compared to perovskite-based ferroelectrics that are currently used in nonvolatile ferroelectric random access memories (FeRAMs). Within the lifetime of the device, two main regimes of wake-up and fatigue can be identified. Up to now, the mechanisms behind these two device stages have not been revealed. Thus, the main scope of this study is an identification of the root cause for the increase of the remnant polarization during the wake-up phase and subsequent polarization degradation with further cycling. Combining the comprehensive ferroelectric switching current experiments, Preisach density analysis, and transmission electron microscopy (TEM) study with compact and Technology Computer Aided Design (TCAD) modeling, it has been found out that during the wake-up of the device no new defects are generated but the existing defects redistribute within the device. Furthermore, vacancy diffusion has been identified as the main cause for the phase transformation and consequent increase of the remnant polarization. Utilizing trap density spectroscopy for examining defect evolution with cycling of the device together with modeling of the degradation results in an understanding of the main mechanisms behind the evolution of the ferroelectric response.

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“…The ESD of state-ofthe-art electrostatic capacitors with various material systems is wileyonlinelibrary.com monoclinic-or tetragonal-phase HfO 2 was not expected to show FE properties. [13][14][15][16][17][18][19] The unexpected FE properties were reported to have resulted from the formation of the noncentrosymmetric orthorhombic phase (o-phase, space group: Pbc2 1 ). It was recently reported that the o-phase can be formed when large tensile stress is asymmetrically applied along the caxis of the tetragonal phase (t-phase, space group: P4 2 /nmc) of Hf x Zr 1-x O 2 (HZO) fi lms.…”

Section: Doi: 101002/aenm201400610mentioning

confidence: 99%

Thin Hf_xZr_1‐xO₂ Films: A New Lead‐Free System for Electrostatic Supercapacitors with Large Energy Storage Density and Robust Thermal Stability

Park

Kim

et al. 2014

Advanced Energy Materials

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314

204

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still smaller than that of electrochemical capacitors due mainly to the use of the low dielectric constant ( ε r ) Al 2 O 3 thin fi lm as the dielectric layer ( ε r ≈ 9). The concurrent high-power capacitors are made mainly of linear dielectric polymers with an ESD of ≈1-2 J cm −3 . [ 3 ] Although the ε r values of linear dielectric polymers are generally small (≈2-5), their electric breakdown fi elds are quite high, thereby allowing the application of high voltages, which result in a relatively high ESD. [ 3 ] Nonetheless, their ESD values are not high enough, so many other materials have been studied for the purpose. Most previous research on this topic focused on AFE Pb(Zr,Ti)O 3 (PZT)-based fi lms because their ESD values are as large as ≈1 and ≈10-15 J cm −3 for bulk and thin fi lms, respectively. [ 3 ] An ESD value as high as ≈50 J cm −3 has been reported for thin PZT-based fi lms when a large ≈3.5 MV cm −1 electric fi eld was applied. [ 7,8 ] However, such a high electric fi eld may induce a signifi cant reliability concern for PZT fi lms. [ 9 ] In addition, the commercial use of PZT is restricted in many countries due to its environmental impact. Another signifi cant problem with PZT thin fi lms is the decrease in their ESD value by ≈20-40% when their operating temperature increases to 150 °C. [ 10,11 ] Other candidate materials are FE poly(vinylidenefl uoride) (PVDF)-based materials, which can have a large breakdown fi eld and maximum polarization. The highest ESD value of FE PVDF-based fi lms has been reported to be as high as ≈20 J cm −3 when a ≈8 MV cm −1 electric fi eld was applied. [ 3 ] However, the problem with such fi lms is that their ESD is only ≈40% of their total stored energy because PVDF is an FE material meaning that ≈60% of the total stored energy is retained in the material. The presence of remanent polarization ( P r ) prohibits the full discharge of the stored charges in any FE material. [ 3 ] In the case of AFE PVDF-based fi lms, an ESD value of ≈14 J cm −3 has been reported with a higher effi ciency of ≈70%. [ 12 ] 3D nanostructures, such as nanoholes or nanotrenches, would be needed to eventually contain an even higher ESD for practical use in electric vehicles. [ 5 ] However, both PZT-and PVDF-based materials are inappropriate for such nanostructures because they are too thick (thickness ( t f ) ≈ 10 2 -10 4 nm) to be incorporated into nanoscale structures. Therefore, a dielectric material that has an ESD value as high as that of PZT and PVDF with a high breakdown fi eld at a fi lm thickness of less than ≈10 nm must be found. The fi lm must also be well grown using the facile atomic layer deposition (ALD) technique to ensure fl uent step coverage with atomic accuracy in thickness control.FE and AFE HfO 2 -based thin fi lms with various dopants, such as Si, Al, and Zr, were recently reported, where the conventional Useful energy sources and ways to effi ciently distribute energy have been extensively studied. With the development of new energy generation and handling technologies, h...

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Ferroelectric properties and switching endurance of Hf_0.5Zr_0.5O₂ films on TiN bottom and TiN or RuO₂ top electrodes

Cited by 135 publications

References 19 publications

Study on the internal field and conduction mechanism of atomic layer deposited ferroelectric Hf_0.5Zr_0.5O₂ thin films

Study on the internal field and conduction mechanism of atomic layer deposited ferroelectric Hf_0.5Zr_0.5O₂ thin films

Physical Mechanisms behind the Field‐Cycling Behavior of HfO₂‐Based Ferroelectric Capacitors

Thin Hf_xZr_1‐xO₂ Films: A New Lead‐Free System for Electrostatic Supercapacitors with Large Energy Storage Density and Robust Thermal Stability

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Ferroelectric properties and switching endurance of Hf0.5Zr0.5O2 films on TiN bottom and TiN or RuO2 top electrodes

Cited by 135 publications

References 19 publications

Study on the internal field and conduction mechanism of atomic layer deposited ferroelectric Hf0.5Zr0.5O2 thin films

Study on the internal field and conduction mechanism of atomic layer deposited ferroelectric Hf0.5Zr0.5O2 thin films

Physical Mechanisms behind the Field‐Cycling Behavior of HfO2‐Based Ferroelectric Capacitors

Thin HfxZr1‐xO2 Films: A New Lead‐Free System for Electrostatic Supercapacitors with Large Energy Storage Density and Robust Thermal Stability

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Ferroelectric properties and switching endurance of Hf_0.5Zr_0.5O₂ films on TiN bottom and TiN or RuO₂ top electrodes

Study on the internal field and conduction mechanism of atomic layer deposited ferroelectric Hf_0.5Zr_0.5O₂ thin films

Study on the internal field and conduction mechanism of atomic layer deposited ferroelectric Hf_0.5Zr_0.5O₂ thin films

Physical Mechanisms behind the Field‐Cycling Behavior of HfO₂‐Based Ferroelectric Capacitors

Thin Hf_xZr_1‐xO₂ Films: A New Lead‐Free System for Electrostatic Supercapacitors with Large Energy Storage Density and Robust Thermal Stability