Highly transparent low capacitance plasma enhanced atomic layer deposition Al2O3-HfO2 tunnel junction engineering

Hajjam, Khalil El; Baboux, Nicolas; Calmon, Françis; Souifi, Abdelkader; Poncelet, Olivier; Francis, Laurent; Ecoffey, Serge; Drouin, Dominique

doi:10.1116/1.4853075

Cited by 14 publications

(9 citation statements)

References 20 publications

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“…The remaining correlations are less important in particular when A d is small compared to A i , as is illustrated above where the values of the effective mass and electron affinity are not significantly affected. The values found for the effective mass are within the range of reported experimental values, i.e., between 0.23 and 0.8 for amorphous ALD deposited Al 2 O 3 [4,[41][42][43][44], and theoretical predictions with values around 0.4 [45,46]. The values found for the electron affinity of Al 2 O 3 are also within the range of reported values of 1.0 eV to 2.5 eV [31,47,48].…”

Section: Resultssupporting

confidence: 84%

Field-enhanced direct tunneling in ultrathin atomic-layer-deposition-grown Au−Al2O3 -Cr metal-insulator-metal structures

et al. 2017

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Metal-insulator-metal structures based on ultrathin high-k dielectric films are underpinning a rapidly increasing number of devices and applications. Here, we report detailed electrical characterizations of asymmetric metalinsulator-metal devices featuring atomic layer deposited 2-nm-thick Al 2 O 3 films. We find a high consistency in the current density as a function of applied electric field between devices with very different surface areas and significant asymmetries in the IV characteristics. We show by TEM that the thickness of the dielectric film and the quality of the metal-insulator interfaces are highly uniform and of high quality, respectively. In addition, we develop a model which accounts for the field enhancement due to the small sharp features on the electrode surface and show that this can very accurately describe the observed asymmetry in the current-voltage characteristic, which cannot be explained by the difference in work function alone.

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Section: Resultssupporting

confidence: 84%

Field-enhanced direct tunneling in ultrathin atomic-layer-deposition-grown Au−Al2O3 -Cr metal-insulator-metal structures

et al. 2017

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“…In the past, mainly precursors belonging to the tetrakis-dialkyl-amido class were used in PEALD processes. Tetrakis-dimethyl-amido hafnium(IV) ([Hf(NMe 2 ) 4 ]), for example, was employed in combination with oxygen plasma at temperatures such as 200 and 250 °C with growth rates of 1.1 and 0.9 Å cycle –1 . While the growth rates were desirably high and in good alignment with those reported for tetrakis-dialkyl-amido precursors in thermal ALD, detailed information about the composition, level of contaminants, and ALD characteristics obtained at the respective deposition temperature were not included in the studies.…”

Section: Introductionmentioning

confidence: 99%

PEALD of HfO₂ Thin Films: Precursor Tuning and a New Near-Ambient-Pressure XPS Approach to in Situ Examination of Thin-Film Surfaces Exposed to Reactive Gases

Zanders¹,

Çiftyürek

Subaşı³

et al. 2019

ACS Appl. Mater. Interfaces

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A bottom-up approach starting with the development of new Hf precursors for plasma-enhanced atomic layer deposition (PEALD) processes for HfO2 followed by in situ thin-film surface characterization of HfO2 upon exposure to reactive gases via near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) is reported. The stability of thin films under simulated operational conditions is assessed, and the successful implementation of HfO2 dielectric layers in metal–insulator–semiconductor (MIS) capacitors is demonstrated. Among the series of newly synthesized mono-guanidinato-tris-dialkyl-amido class of Hf precursors, one of them, namely, [Hf{η2-( i PrN)2CNEtMe}(NEtMe)3], was representatively utilized with oxygen plasma, resulting in a highly promising low-temperature PEALD process at 60 °C. The new precursors were synthesized in the multigram scale and thoroughly characterized by thermogravimetric analyses, revealing high and tunable volatility reflected by appreciable vapor pressures and accompanied by thermal stability. Typical ALD growth characteristics in terms of linearity, saturation, and a broad ALD window with constant growth of 1.06 Å cycle–1 in the temperature range of 60–240 °C render this process very promising for fabricating high-purity smooth HfO2 layers. For the first time, NAP-XPS surface studies on selected HfO2 layers are reported upon exposure to reactive H2, O2, and H2O atmospheres at temperatures of up to 500 °C revealing remarkable stability against degradation. This can be attributed to the absence of surface defects and vacancies. On the basis of these promising results, PEALD-grown HfO2 films were used as dielectric layers in the MIS capacitor device fabrication exhibiting leakage current densities less than 10–7 A cm–2 at 2 MV cm–1 and permittivities of up to 13.9 without postannealing.

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“…Various attempts have been made to obtain excellent HfO 2 dielectric films using the atomic layer deposition (ALD) method. [26][27][28][29][30][31][32][33][34][35][36] Table 1 presents a literature overview for the HfO 2 films with various Hf precursors and reactant gases by the ALD process. For fabricating the HfO 2 films, two ligand types of precursors were typically used: an amine-based type and a cyclopentadiene-based type.…”

Section: Characteristics Of Peald-hfo 2 Filmsmentioning

confidence: 99%

Characteristics of PEALD–Hafnium Dioxide Films and their Application to Gate Insulator Stacks of Photosynaptic Transistors

Kim

Lim

Lee

2021

Adv Elect Materials

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For practical applications of photosynaptic devices in neuromorphic systems, photosynaptic transistors prepared using TiO2 channels and TiO2/Al2O3 deep trap interfaces exhibit high stability and retention. However, there is scope for improving photosynaptic properties such as large numbers of analog states with good linearity and high sensitivity. Herein, HfO2 thin films of high‐κ gate dielectric layers grown by plasma‐enhanced atomic layer deposition with the Hf precursor methyl‐3‐cyclopentadiene propylamine bis(dimethylamino) hafnium are employed. 30‐nm‐thick HfO2 films deposited at 200 °C exhibit a κ of 13.4 and an E‐field of up to 5 MV cm−1. They are grown on a Si substrate and appropriately used in the form of double‐insulator stacks, in addition to Al2O3, in TiO2‐based photosynaptic transistors. The synaptic transistors successfully demonstrate better performance in terms of various parameters relevant to synaptic plasticity. For long‐term plasticity, 256 analog states are observed, which is more than that reported previously, with superior linearity. Moreover, lights of various wavelengths, including visible and UV, are illuminated on the devices, resulting in various lifetimes (wavelength‐dependent) of the trapped carriers. These properties are commercially attractive and suggest the feasibility of employing these devices in applications such as visual information detection and computing in future intelligent networks.

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Highly transparent low capacitance plasma enhanced atomic layer deposition Al2O3-HfO2 tunnel junction engineering

Cited by 14 publications

References 20 publications

Field-enhanced direct tunneling in ultrathin atomic-layer-deposition-grown Au−Al2O3 -Cr metal-insulator-metal structures

Field-enhanced direct tunneling in ultrathin atomic-layer-deposition-grown Au−Al2O3 -Cr metal-insulator-metal structures

PEALD of HfO₂ Thin Films: Precursor Tuning and a New Near-Ambient-Pressure XPS Approach to in Situ Examination of Thin-Film Surfaces Exposed to Reactive Gases

Characteristics of PEALD–Hafnium Dioxide Films and their Application to Gate Insulator Stacks of Photosynaptic Transistors

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Highly transparent low capacitance plasma enhanced atomic layer deposition Al2O3-HfO2 tunnel junction engineering

Cited by 14 publications

References 20 publications

Field-enhanced direct tunneling in ultrathin atomic-layer-deposition-grown Au−Al2O3 -Cr metal-insulator-metal structures

Field-enhanced direct tunneling in ultrathin atomic-layer-deposition-grown Au−Al2O3 -Cr metal-insulator-metal structures

PEALD of HfO2 Thin Films: Precursor Tuning and a New Near-Ambient-Pressure XPS Approach to in Situ Examination of Thin-Film Surfaces Exposed to Reactive Gases

Characteristics of PEALD–Hafnium Dioxide Films and their Application to Gate Insulator Stacks of Photosynaptic Transistors

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PEALD of HfO₂ Thin Films: Precursor Tuning and a New Near-Ambient-Pressure XPS Approach to in Situ Examination of Thin-Film Surfaces Exposed to Reactive Gases