Superior and stable ferroelectric properties of hafnium-zirconium-oxide thin films deposited <i>via</i> atomic layer deposition using cyclopentadienyl-based precursors without annealing

Kim, Hyo‐Bae; Jung, Moonyoung; Oh, Youkyoung; Lee, Seungwon; Suh, Dongseok; Ahn, Ji‐Hoon

doi:10.1039/d1nr01535d

Cited by 24 publications

(15 citation statements)

References 35 publications

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“…However, employing a higher deposition temperature can produce a high-quality film with low impurity concentration and high density, resulting in low-temperature crystallization. Accordingly, Kim et al demonstrated the benefit of using higher deposition temperatures by depositing HZO films with a cocktail precursor containing CpHf and CpZr . For deposition, cocktail precursors with a molecular ratio of 35:65 for CpHf and CpZr, respectively, were used.…”

Section: Atomic Layer Depositionmentioning

confidence: 99%

“…Accordingly, Kim et al demonstrated the benefit of using higher deposition temperatures by depositing HZO films with a cocktail precursor containing CpHf and CpZr. 60 For deposition, cocktail precursors with a molecular ratio of 35:65 for CpHf and CpZr, respectively, were used. For adequate vapor pressure, the precursor had to be heated and bubbled.…”

Section: Atomic Layer Depositionmentioning

confidence: 99%

“…The amount of dopant can be controlled by changing the number of dopant cycles inserted into the HfO 2 deposition cycles, resulting in a supercycle, which is a repeating cycle of HfO 2 and dopant cycles . Numerous researchers have employed this ALD doping technique to achieve ferroelectricity in HfO 2 using various dopants, including Al, , Si, − Y, La, , Sr, , Gd, and Zr. ,,,− Doping HfO 2 with Gd, Sr, La, Y, and Zr showed an improvement in 2 P r values compared to pure HfO 2 , as demonstrated in Figure a, satisfying the minimum switching charge density requirement (24.0 μC/cm 2 ) for FRAM applications according to International Roadmap for Devices and Systems . Moreover, the presence of Gd and Zr as dopants in HfO 2 also helped achieve ferroelectricity at temperatures compatible with the BEOL process (<450 °C).…”

Section: Atomic Layer Depositionmentioning

confidence: 99%

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Toward Low-Thermal-Budget Hafnia-Based Ferroelectrics via Atomic Layer Deposition

Kim,

Onaya,

Park

et al. 2023

ACS Appl. Electron. Mater.

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Since the first report of ferroelectricity in fluorite structure oxides a decade ago, significant attention has been devoted to studying hafnia-based ferroelectric material systems due to their promising properties and opportunities. To achieve such ferroelectric fluorite structure oxides at low temperatures (below 400 °C), stabilizing the metastable noncentrosymmetric orthorhombic phase is crucial. This review provides a comprehensive overview of atomic layer deposition (ALD) techniques for obtaining the orthorhombic phase for low-temperature ferroelectric applications. We discuss optimization of the ALD process for synthesizing high-quality, low-temperature crystallizing ferroelectric films, including doping, precursor and oxygen source selection, deposition temperature, and interface engineering. In addition, the techniques for stabilizing the ferroelectric phase by regulating the thermal budget and stress with various annealing methods and stressors are discussed. The review focuses on different techniques to reduce the thermal budget required to acquire ferroelectricity, making hafnia-based ferroelectric materials compatible with back-end-of-line and three-dimensional integration for a variety of future applications, including flexible electronics applications.

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Section: Atomic Layer Depositionmentioning

confidence: 99%

Section: Atomic Layer Depositionmentioning

confidence: 99%

Section: Atomic Layer Depositionmentioning

confidence: 99%

See 1 more Smart Citation

Toward Low-Thermal-Budget Hafnia-Based Ferroelectrics via Atomic Layer Deposition

Kim,

Onaya,

Park

et al. 2023

ACS Appl. Electron. Mater.

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“…Compared with traditional ferroelectric materials such as Pb(Zr,Ti)O 3 (PZT) and P(VDF-TrFE), hafnium-based ferroelectric films show the advantages of high residual polarization strength ( P r ), high Curie temperature ( T c > 200 °C), high compatibility with CMOS process, good interface performance with semiconductor materials, and high dielectric constant . Ferroelectricity can be observed in the doped HfO 2 film with a thickness of less than 10 nm, − which makes it suitable for small-sized devices.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Subthreshold Swing and Hysteresis in Hf_0.5Zr_0.5O₂-Based MoS₂ Negative Capacitance Field-Effect Transistors by Modulating Capacitance Matching

Guo

Wang

et al. 2023

ACS Appl. Mater. Interfaces

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Negative capacitance field effect transistors made of Hf0.5Zr0.5O2 (HZO) are one of the most promising candidates for low-power-density devices because of the extremely steep subthreshold swing and high open-state currents resulting from the addition of ferroelectric materials in the gate dielectric layer. In this paper, HZO thin films were prepared by magnetron sputtering combined with rapid thermal annealing. Their ferroelectric properties were adjusted by changing the annealing temperature and the thickness of HZO. Two-dimensional MoS2 back-gate negative capacitance field-effect transistors (NCFETs) based on HZO were prepared as well. Different annealing temperatures, thicknesses of HZO thin films, and Al2O3 thicknesses were studied to achieve optimal capacitance matching, aiming to reduce both the subthreshold swing of the transistor and the hysteresis of the NCFET. The NCFET exhibits a minimum subthreshold swing as low as 27.9 mV/decade, negligible hysteresis (∼20 mV), and the I ON/I OFF of up to 1.58 × 107. Moreover, a negative drain-induced barrier lowering effect and a negative differential resistance effect have been observed. This steep-slope transistor is compatible with standard CMOS manufacturing processes and attractive for 2D logic and sensor applications as well as future energy-efficient nanoelectronic devices with scaled power supplies.

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“…These precursors, however, sometimes have drawbacks such as halide contamination and low stabilities in the case of the halide and alkoxides, respectively. Consequently, heteroleptic precursors including more than one type of ligands such as cyclopentadienyl (Cp)-alkoxides and Cp-alkylamides are developed, to enhance the thermal stability of precursors of the ALD high-k oxides. − When ozone is used as the oxygen source, ALD using zirconium and hafnium Cp-alkylamide precursors shows high growth per cycle (GPC), ranging from 0.8 to 0.9 Å per cycle, and the deposited films mostly possessed low levels of nitrogen and carbon contamination. Especially, ZrO 2 and HfO 2 films deposited using CpZr(N(Me 2 ) 3 and CpHf(N(Me 2 ) 3 precursors (Me = CH 3 ) and ozone have shown improved film density and electrical performance, possibly due to the deposition temperatures being as high as 350 °C.…”

Section: Introductionmentioning

confidence: 99%

Role of Cyclopentadienyl Ligands of Group 4 Precursors toward High-Temperature Atomic Layer Deposition

et al. 2022

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Deposition of high-k dielectric thin films is essential for manufacturing modern electronic devices. Atomic layer deposition (ALD) is an attractive technology for depositing high-k materials because it exhibits conformality and facilitates thickness control of the films at the atomic level. It has been suggested that high-temperature ALD can enhance the material properties of the deposited films such as density and crystallinity, for which the development of thermally stable precursors that deliver the metallic element is required. Heteroleptic titanium (Ti), zirconium (Zr), and hafnium (Hf) precursors containing amido and cyclopentadienyl (Cp) ligands have recently been introduced, with some demonstrating improved thermal stability. However, the mechanism behind the improved thermal stability of these precursors remains unclear. This research employs density functional theory (DFT) calculations to elucidate the role of Cp ligands of group 4 (Ti, Zr, Hf) precursors for high-temperature ALD. The surface adsorption reactions of the precursors on oxide surfaces are suggested to be facile. For most precursors, one or two ligands are thought to exist after chemical adsorption. Cp ligands, in particular, are expected to persist on the surface, whereas amido ligands are more easily eliminated during adsorption. The decomposition of the precursor after adsorption on the surface then is considered, for which the thermal stability is significantly enhanced by introducing the Cp ligand. Furthermore, precursors with Cp ligands are more difficult to adsorb on the partially decomposed precursor-on-surface. Our findings intend to offer a fundamental molecular-level understanding of the thermal stability of group 4 precursors for high-temperature ALD.

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Superior and stable ferroelectric properties of hafnium-zirconium-oxide thin films deposited via atomic layer deposition using cyclopentadienyl-based precursors without annealing

Abstract: The superior and stable ferroelectric properties of HZO films deposited via ALD were demonstrated for the first time without a post-thermal process, which can be applied to ferroelectric devices where process temperature constraints are required.

Cited by 24 publications

References 35 publications

Toward Low-Thermal-Budget Hafnia-Based Ferroelectrics via Atomic Layer Deposition

Toward Low-Thermal-Budget Hafnia-Based Ferroelectrics via Atomic Layer Deposition

Optimization of Subthreshold Swing and Hysteresis in Hf_0.5Zr_0.5O₂-Based MoS₂ Negative Capacitance Field-Effect Transistors by Modulating Capacitance Matching

Role of Cyclopentadienyl Ligands of Group 4 Precursors toward High-Temperature Atomic Layer Deposition

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Superior and stable ferroelectric properties of hafnium-zirconium-oxide thin films deposited via atomic layer deposition using cyclopentadienyl-based precursors without annealing

Abstract: The superior and stable ferroelectric properties of HZO films deposited via ALD were demonstrated for the first time without a post-thermal process, which can be applied to ferroelectric devices where process temperature constraints are required.

Cited by 24 publications

References 35 publications

Toward Low-Thermal-Budget Hafnia-Based Ferroelectrics via Atomic Layer Deposition

Toward Low-Thermal-Budget Hafnia-Based Ferroelectrics via Atomic Layer Deposition

Optimization of Subthreshold Swing and Hysteresis in Hf0.5Zr0.5O2-Based MoS2 Negative Capacitance Field-Effect Transistors by Modulating Capacitance Matching

Role of Cyclopentadienyl Ligands of Group 4 Precursors toward High-Temperature Atomic Layer Deposition

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Optimization of Subthreshold Swing and Hysteresis in Hf_0.5Zr_0.5O₂-Based MoS₂ Negative Capacitance Field-Effect Transistors by Modulating Capacitance Matching