Nonvolatile Random Access Memory and Energy Storage Based on Antiferroelectric Like Hysteresis in ZrO<sub>2</sub>

Pešić, Milan; Hoffmann, Michael; Richter, Claudia; Mikolajick, Thomas; Schroeder, Uwe

doi:10.1002/adfm.201603182

Cited by 190 publications

(85 citation statements)

References 33 publications

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“…The corresponding potential to explain the field-induced phase transition equals that of a first-order phase transition slightly above the Curie temperature with a stable centric minimum (unipolar state, tetragonal phase) and two symmetric, metastable eccentric minima (ferroelectric phase with two spontaneous polarization states). Here, no strong effect of internal bias fields is anticipated (at least in a perfectly symmetric stack [50] ) as no polar grains are present that could promote a certain defect/charge movement/formation. By applying a certain positive or negative field, this potential can be tilted as shown in Figure 6c and one of the polar states becomes the new stable state.…”

Section: Wwwadvelectronicmatdementioning

confidence: 94%

Si Doped Hafnium Oxide—A “Fragile” Ferroelectric System

Richter

Schenk

Park

et al. 2017

Adv Elect Materials

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152

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a wealth of different elements from the periodic table [7][8][9] have since exhibited ferroelectric properties. In their original publication, Böscke et al. [10] used ≈10 nm thick films of Si:HfO 2 and found the electrical behavior to evolve from paraelectric (PE) to ferroelectric (FE) and antiferroelectriclike to paraelectric again with a continuous increase in the Si dopant concentration. A similar electric evolution has also been shown for aluminum doping [11] and for (Hf,Zr)O 2 . [6,12] For the latter, an advanced understanding of the phase stabilization could be established, assisted in part by the very wide concentration window over which the changes occur. Ab initio calculations [13] interrogated the impact of surface energy in this system, revealing a phase transition from monoclinic pure HfO 2 to orthorhombic Hf 0.5 Zr 0.5 O 2 to tetragonal pure ZrO 2 for 10 nm film thickness, which aligns well the experimental observations. Moreover, inclusion of an electric field effect explained the antiferroelectriclike polarization hysteresis of pure ZrO 2 as the result of a fieldinduced phase transition from a nonpolar tetragonal to a polar orthorhombic phase. [6,13,14] Thus, instead of the term antiferroelectricity, field-induced ferroelectricity (FFE) is becoming a more precise and commonly used way to describe this behavior. While Si:HfO 2 and Al:HfO 2 have quickly been used in applications such as ferroelectric field effect transistors in 28 nm technology [15,16] and 3D capacitors, [17] basic material studies of doped ferroelectric HfO 2 have lagged those of the (Hf,Zr) O 2 system. By exploring a wide Si concentration range in fine steps, this work aims to gain insight into the phase transformations that occur in a doped HfO 2 system. Results and Discussion Impact of Annealing ConditionsAs a first step, planar capacitor stacks (Figure 1) with ≈36 nm thick HfO 2 films are deposited using a 22:1 HfO 2 :SiO 2 cycle ratio. As shown later, this results in a Si content that is slightly higher than the one that has produced the highest remanent polarization P r values in this study (Figure 7). As visible in Figure 2, the P r (measured under an electric field of 4 MV cm −1 and 10 kHz) increases for anneals at higher temperatures.Silicon doped hafnium oxide was the material used in the original report of ferroelectricity in hafnia in 2011. Since then, it has been subject of many further publications including the demonstration of the world's first ferroelectric field-effect transistor in the state-of-the-art 28 nm technology. Though many studies are conducted with a strong focus on application in memory devices, a comprehensive study on structural stability in these films remains to be seen. In this work, a film thickness of about 36 nm, instead of the 10 nm used in most previous studies, is utilized to carefully probe how the concentration range impacts the evolution of phases, the dopant distribution, the field cycling effects, and their interplay in the macroscopic ferroelectric response of the films. Si:HfO 2 appear...

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Section: Wwwadvelectronicmatdementioning

confidence: 94%

Si Doped Hafnium Oxide—A “Fragile” Ferroelectric System

Richter

Schenk

Park

et al. 2017

Adv Elect Materials

Self Cite

152

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show abstract

“…For pure HfO 2 , a paraelectric response is typically observed due to the stabilization of the monoclinic phase. For pure ZrO 2 , in contrast, antiferroelectric behavior was reported that is attributed to the tetragonal phase and an electric field–driven phase transition to the orthorhombic phase . For La doping of HfO 2 , Schroeder et al reported a remanent polarization ( P r ) of more than 30 µC cm −2 if doped in with a concentration of about 10 cat%.…”

Section: Introductionmentioning

confidence: 99%

Bulk Depolarization Fields as a Major Contributor to the Ferroelectric Reliability Performance in Lanthanum Doped Hf_0.5Zr_0.5O₂ Capacitors

Mehmood

Hoffmann

Lomenzo

et al. 2019

Adv Materials Inter

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108

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After the discovery of ferroelectricity in HfO2, many dopants have been incorporated into the material to improve the ferroelectric properties. The binary mixture of HfO2 and ZrO2, HfxZrx−1O2, showed the widest process window in terms of polarization, but other memory related aspects still need improvement. Recently, the co‐doping of La into a mixed Hf0.5Zr0.5O2, La:HZO, was reported to improve the endurance properties further but the explanation spanning both structural and electrical characteristics of La:HZO and their interaction is still missing. In this work, an extensive study of La:HZO with La content ranging from 0 to 4.3 mol% is conducted and resultant stabilization of nonpolar tetragonal phase, coercive field reduction, endurance improvement, stronger retention loss, and less imprinted hysteresis loop is reported with increasing La concentration. The model simultaneously explaining the electrical and structural properties is presented. In ferroelectric capacitor structures, the depolarization fields originating from nonferroelectric layers at the metal/ferroelectric interface are discussed extensively in previous studies but, here, for the first time, the impact of depolarization fields from nonferroelectric regions in the bulk of the ferroelectric material is reported, which is an important element to explain all the observed trends.

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“…Therefore this discovery has drastically changed the view on ferroelectric memories [19]. Both the scaling of classical capacitor based memories as well as the realization of FeFET based memories seem to be in reach again [20,21] and even the possibility of making classical DRAM non-volatile has been pointed out recently [22,23]. However, in order to apply the unexpected ferroelectric behavior of hafnium oxide to reliable products a number of fundamental questions need to be answered: the origin of the ferroelectric phase, the control of the influencing process parameters, the device and array concepts as well as the degradation under use conditions.…”

Section: Introductionmentioning

confidence: 99%

A computational study of hafnia-based ferroelectric memories: from ab initio via physical modeling to circuit models of ferroelectric device

et al. 2017

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Abstract. The discovery of ferroelectric properties of binary oxides revitalized the interest in ferroelectrics and bridged the scaling gap between the state-of-the-art semiconductor technology and ferroelectric memories. However, before hitting the markets, the origin of ferroelectricity and in-depth studies of device characteristics are needed. Establishing a correlation between the performance of the device and underlying physical mechanisms is the first step toward understanding the device and engineering guidelines for a novel, superior device. Therefore, in this paper a holistic modeling approaches which lead to a better understanding of ferroelectric memories based on hafnium and zirconium oxide is addressed. Starting from describing the stabilization of the ferroelectric phase within the binary oxides via physical modeling the physical mechanisms of the ferroelectric devices are reviewed. Besides, limitations and modeling of the multi-level operation and switching kinetics of ultimately scaled devices as well as the necessity for Landau-Khalatnikov approach are discussed. Furthermore, a device level model of ferroelectric memory devices that can be used to study the array implementation and their operational schemes are addressed. Finally, a circuit model of the ferroelectric memory device is presented and potential further applications of ferroelectric devices are outlined.

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Nonvolatile Random Access Memory and Energy Storage Based on Antiferroelectric Like Hysteresis in ZrO₂

Cited by 190 publications

References 33 publications

Si Doped Hafnium Oxide—A “Fragile” Ferroelectric System

Si Doped Hafnium Oxide—A “Fragile” Ferroelectric System

Bulk Depolarization Fields as a Major Contributor to the Ferroelectric Reliability Performance in Lanthanum Doped Hf_0.5Zr_0.5O₂ Capacitors

A computational study of hafnia-based ferroelectric memories: from ab initio via physical modeling to circuit models of ferroelectric device

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Nonvolatile Random Access Memory and Energy Storage Based on Antiferroelectric Like Hysteresis in ZrO2

Cited by 190 publications

References 33 publications

Si Doped Hafnium Oxide—A “Fragile” Ferroelectric System

Si Doped Hafnium Oxide—A “Fragile” Ferroelectric System

Bulk Depolarization Fields as a Major Contributor to the Ferroelectric Reliability Performance in Lanthanum Doped Hf0.5Zr0.5O2 Capacitors

A computational study of hafnia-based ferroelectric memories: from ab initio via physical modeling to circuit models of ferroelectric device

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Product

Resources

About

Nonvolatile Random Access Memory and Energy Storage Based on Antiferroelectric Like Hysteresis in ZrO₂

Bulk Depolarization Fields as a Major Contributor to the Ferroelectric Reliability Performance in Lanthanum Doped Hf_0.5Zr_0.5O₂ Capacitors