Ferroelectric Hf0.5Zr0.5O2 Thin Films: A Review of Recent Advances

Kim, Si Joon; Mohan, Jaidah; Summerfelt, Scott R.; Kim, Jiyoung

doi:10.1007/s11837-018-3140-5

Cited by 248 publications

(226 citation statements)

References 85 publications

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“…It is known that the fraction of the m‐phase increases with film thickness. However, usually reasonable amounts of this phase are detected only for films exceeding 20 nm . The reason for detection here at 20 nm could be the partial crystallization of the films during the deposition process.…”

Section: Resultsmentioning

confidence: 88%

“…However, their challenging integration due to incompatibility with complementary metal–oxide–semiconductor (CMOS) technologies has limited their use to niche applications and restricted scaling below the 90 nm node. This is particularly because the conventional FEs require high film thicknesses, high annealing temperatures, and provide rather small coercive and breakdown fields as well as high dielectric constants …”

Section: Introductionmentioning

confidence: 99%

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Back‐End‐of‐Line Compatible Low‐Temperature Furnace Anneal for Ferroelectric Hafnium Zirconium Oxide Formation

Lehninger

Olivo

Ali

et al. 2020

Physica Status Solidi (a)

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The discovery of ferroelectricity in thin doped hafnium oxide films revived the interest in ferroelectric (FE) memory concepts. Zirconium‐doped hafnium oxide (HZO) crystallizes at low temperatures (e.g., 400 °C), which makes this material interesting for the implementation of FE functionalities into the back end of line (BEoL). So far, the FE phase of prior amorphous HZO films is achieved by using a dedicated rapit thermal annealing (RTA) treatment. However, herein, it is shown that this dedicated anneal is not needed. A sole furnace treatment given by the thermal budget present during the interconnect formation is sufficient to functionalize even ultrathin 5 nm HZO films. This result helps to optimize the integration sequence of HZO films (e.g., involving a minimum number of BEoL process steps), which saves process time and fabrication costs. Herein, metal–FE–metal capacitors with Hf0.5Zr0.5O2 films of different thicknesses (5–20 nm) are fabricated annealed at 400 °C for various durations within different types of ovens (RTA and furnace). Structural and electrical characterization confirms that all furnace‐annealed samples have similar X‐ray diffraction patterns, remanent polarization, endurances, and thickness dependencies as RTA‐annealed ones. With respect to remanent polarization, leakage current, and endurance, the HZO film of 10 nm thickness shows the most promising results for the integration into the BEoL.

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Section: Resultsmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Back‐End‐of‐Line Compatible Low‐Temperature Furnace Anneal for Ferroelectric Hafnium Zirconium Oxide Formation

Lehninger

Olivo

Ali

et al. 2020

Physica Status Solidi (a)

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“…10 The resulting films are polycrystalline and contain paraelectric tetragonal and monoclinic phases besides the ferroelectric orthorhombic phase. 1,2,[11][12] The ferroelectric phase has been also grown epitaxially on a few substrates, including yttria-stabilized zirconia, [13][14][15][16] LaAlO3, 17 SrTiO3, [18][19][20][21] and buffered Si. 22 The research on epitaxial stabilization is just emerging in comparison with that on polycrystalline doped HfO2 films.…”

Section: Introductionmentioning

confidence: 99%

“…22 The research on epitaxial stabilization is just emerging in comparison with that on polycrystalline doped HfO2 films. 2,5,8,[10][11][12]23 However, epitaxial HfO2 films are of huge interest as their properties can be better controlled than those of polycrystalline samples. Besides the single crystal orientation in epitaxial films, the control of the epitaxial stress can permit engineering of the microstructure and the resulting ferroelectric properties of the films.…”

Section: Introductionmentioning

confidence: 99%

Engineering Ferroelectric Hf_0.5Zr_0.5O₂ Thin Films by Epitaxial Stress

Estandía

Dix

Gàzquez

et al. 2019

ACS Appl. Electron. Mater.

128

195

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The critical impact of epitaxial stress on the stabilization of the ferroelectric orthorhombic phase of hafnia is proved. Epitaxial bilayers of Hf0.5Zr0.5O2 (HZO) andLa0.67Sr0.33MnO3 (LSMO) electrodes were grown on a set of single crystalline oxide (001)oriented (cubic or pseudocubic setting) substrates with lattice parameter in the 3.71 -4.21 Å range. The lattice strain of the LSMO electrode, determined by the lattice mismatch with the substrate, is critical in the stabilization of the orthorhombic phase of HZO. On LSMO electrodes tensile strained most of the HZO film is orthorhombic, whereas the monoclinic phase is favored when LSMO is relaxed or compressively strained. Therefore, the HZO films on TbScO3 and GdScO3 substrates present substantially enhanced ferroelectric polarization in comparison to films on other substrates, including the commonly used SrTiO3. The capability of having epitaxial doped HfO2 films with controlled phase and polarization is of major interest for a better understanding of the ferroelectric properties and paves the way for fabrication of ferroelectric devices based on nanometric HfO2 films.

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“…It also outperforms other ferroelectric materials such as Pb(Zr,Ti)O 3 (PZT) that has a small bandgap and requires a large thickness to reduce the leakage current, which are difficult to be grown by ALD or chemical vapor deposition (CVD). [ 23 ] Similarly, organic poly(vinylidene fluoride‐trifluoroethylene) (P(VDF‐TrFE)) materials are suffering from incompatibility with CMOS integration. [ 24,25 ] In contrast, 2D materials such as graphene, transition metal dichalcogenides (TMDs), and black phosphorus, have attracted growing attention due to their ultrathin geometry and unique electronic properties, which allow aggressive scaling and excellent electrostatic control.…”

Section: Introductionmentioning

confidence: 99%

A van der Waals Synaptic Transistor Based on Ferroelectric Hf_0.5Zr_0.5O₂ and 2D Tungsten Disulfide

Chen

Wang

Peng

et al. 2020

Adv Elect Materials

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Neuromorphic computing on the hardware level is promising for performing ever‐increasing data‐centric tasks owing to its superiority to conventional von Neumann architecture in terms of energy efficiency and learning ability. One key aspect to its implementation is the development of artificial synapses that can effectively emulate the multiple functionalities exhibited by their biological counterparts. Here, building on an inorganic ferroelectric gate stack integrated with a 2D layered semiconductor (WS2), a new type of ferroelectricity‐based synaptic transistor that differs from those relying on interface traps or floating gate configuration is reported. By virtue of a 6 nm thick ferroelectric hafnium zirconium oxide by atomic layer deposition and postannealing treatment, the device shows a channel resistance change ratio above 105 corresponding to opposite ferroelectric polarization direction. Furthermore, by applying electrical stimulus to the gate, it demonstrates good capability to mimic various synaptic behaviors including long‐term potentiation, long‐term depression, spike‐amplitude‐dependent plasticity, and spike‐rate‐dependent plasticity. Given the inherent compatibility of the ferroelectric gate stack with existing fabrication technology, and the reliability of ferroelectricity engineering, this work paves the way toward practical implementation of synaptic devices in neuromorphic circuits.

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Ferroelectric Hf0.5Zr0.5O2 Thin Films: A Review of Recent Advances

Cited by 248 publications

References 85 publications

Back‐End‐of‐Line Compatible Low‐Temperature Furnace Anneal for Ferroelectric Hafnium Zirconium Oxide Formation

Back‐End‐of‐Line Compatible Low‐Temperature Furnace Anneal for Ferroelectric Hafnium Zirconium Oxide Formation

Engineering Ferroelectric Hf_0.5Zr_0.5O₂ Thin Films by Epitaxial Stress

A van der Waals Synaptic Transistor Based on Ferroelectric Hf_0.5Zr_0.5O₂ and 2D Tungsten Disulfide

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Ferroelectric Hf0.5Zr0.5O2 Thin Films: A Review of Recent Advances

Cited by 248 publications

References 85 publications

Back‐End‐of‐Line Compatible Low‐Temperature Furnace Anneal for Ferroelectric Hafnium Zirconium Oxide Formation

Back‐End‐of‐Line Compatible Low‐Temperature Furnace Anneal for Ferroelectric Hafnium Zirconium Oxide Formation

Engineering Ferroelectric Hf0.5Zr0.5O2 Thin Films by Epitaxial Stress

A van der Waals Synaptic Transistor Based on Ferroelectric Hf0.5Zr0.5O2 and 2D Tungsten Disulfide

Contact Info

Product

Resources

About

Engineering Ferroelectric Hf_0.5Zr_0.5O₂ Thin Films by Epitaxial Stress

A van der Waals Synaptic Transistor Based on Ferroelectric Hf_0.5Zr_0.5O₂ and 2D Tungsten Disulfide