Uniform and robust TiN/HfO2/Pt memristor through interfacial Al-doping engineering

Zhu, Yaxin; Xue, Kaiping; Cheng, Xiaomin; Qiao, Chong; Yuan, Jianming; Li, Li-Heng; Miao, Xiangshui

doi:10.1016/j.apsusc.2021.149274

Cited by 46 publications

(30 citation statements)

References 37 publications

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“…The peak at 530.5 eV was associated with oxygen bonded to hafnium (i.e., HfO 2 ) and is known as the lattice peak. Meanwhile, the peak at 532.0 eV, known as the nonlattice peak, was observed in the region where the bonding between hafnium and oxygen was partially broken and served as a defect related to the presence of oxygen vacancies. , Figure a shows the O 1s spectra of the active layer with the Ti TE without PMA and with PMA at 400 °C for 1 h, respectively. As shown in Figure aa (top), the Ti TE-HM shows both lattice and nonlattice peaks in the O 1s spectra, and the proportion of the nonlattice peak in the peak sum was 23.41%.…”

Section: Resultsmentioning

confidence: 99%

Analysis of the Thermal Degradation Effect on a HfO₂-Based Memristor Synapse Caused by Oxygen Affinity of a Top Electrode Metal and on a Neuromorphic System

Park

Kim

et al. 2021

ACS Appl. Electron. Mater.

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The thermal budget problem needs to be considered for a neuromorphic system based on a memristor to be compatible with silicon-based devices. The thermal degradation caused by postmetal annealing (PMA) was investigated for HfO 2based memristor (HM) devices at temperatures above 300 °C to ensure the thermal stability of memristor devices and analyze the effect of thermal degradation on the neuromorphic system. As thermal degradation is caused by oxygen atom movement between the interlayer and the top electrode (TE), the thermal stability of the memristor can be improved by adjusting the oxygen affinity of the TE metal. By changing the TE metal from titanium (Ti) to tantalum (Ta), the resistance of the high-resistance state and resistance variability after PMA at 400 °C for 1 h decreased from 516 to 10% and from 21 to 4%, respectively. In addition, pattern recognition simulation was performed using an artificial neural network consisting of a memristor device. Although the pattern recognition simulation with the Ti TE-HM showed a pattern recognition accuracy of 82.3% after PMA owing to thermal degradation, the simulation with the Ta TE-HM showed a high accuracy of 51.7% even after PMA. This experimental approach can facilitate the development of neuromorphic systems with good thermal stability up to 400 °C.

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Section: Resultsmentioning

confidence: 99%

Analysis of the Thermal Degradation Effect on a HfO₂-Based Memristor Synapse Caused by Oxygen Affinity of a Top Electrode Metal and on a Neuromorphic System

Park

Kim

et al. 2021

ACS Appl. Electron. Mater.

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“…Thus, the Zr x Al y O z interfacial layer could perform as a reservoir of defects below the host ZrO 2 and, possibly, be a source of ionic current. Application of a similar interface layer has recently been reported in studies of TiN/HfO 2 :Al/HfO 2 /Pt [37] and Pt/Al 2 O 3 /HfO 2 /HfAlO x /TiN [38] RRAM stacks. In the present study, the content of aluminum in the Zr x Al y O z buffer layer was expected to be lower than that of zirconium, because in the successive exposures of surface to ZrCl 4 and Al(CH 3 ) 3 without intermittent supply of oxygen precursor, the incorporation of zirconium into the film material was more likely than that of aluminum.…”

Section: Methodsmentioning

confidence: 84%

Structure and Electrical Properties of Zirconium-Aluminum-Oxide Films Engineered by Atomic Layer Deposition

et al. 2022

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Thin films containing either multilayer ZrO2:Al2O3 structures or ZrO2 deposited on ZrxAlyOz buffer layers were characterized. The films were grown by atomic layer deposition (ALD) at 300 °C from ZrCl4, Al(CH3)3, and H2O. The multilayer ZrO2:Al2O3 structures were grown repeating different combinations of ZrO2 and Al2O3 ALD cycles while the ZrxAlyOz layers were obtained in a novel process using ALD cycles based on successive adsorption of ZrCl4 and Al(CH3)3, followed by surface reaction with H2O. The films were grown on TiN electrodes, and supplied with Ti top electrodes, whereby ZrxAlyOz films were exploited as thin buffer layers between TiN and ZrO2. The as-deposited ZrO2 films and ZrO2:Al2O3 structures with sufficiently low concentrations of Al2O3 were crystallized in the form of cubic or tetragonal ZrO2 polymorph possessing relative permittivities reaching 35. Notably, multilayered ZrO2:Al2O3 films could exhibit resistive switching behavior with ratios between low- and high-resistive-state current values, extending up to five orders of magnitude. Implications of multilevel switching were recorded. In the double-layered ZrxAlyOz-ZrO2 stacks, the ON/OFF current ratios remained below 40, but the endurance could become extended over 3000 cycles. Remarkably, instabilities, when detected in endurance behavior expressed by reduction in an ON/OFF current ratio could be compensated and the current values restored by real time readjustment of the programming voltage amplitude.

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“…An electroforming process was preceded by applying −6 V with a 10 –5 A of compliance current ( I cc ) to prevent permanent breakdown. After electroforming, a typical bipolar resistive switching characteristic can be observed; the device was set from a high-resistance state (HRS) to a low-resistance state (LRS) at about −1.2 V, and reset from the LRS to the HRS at about +1.5 V. ,− Also, it showed an analog switching characteristic in a DC I – V sweep, as shown in Figure b. Here, the device was set-switched gradually from the HRS by increasing I cc from 0.05 mA (dark green) to 2 mA (light green) during a negative DC I – V cycle from 0 to −2 V. Afterward, the device was gradually reset from the LRS by a positive DC I – V cycle from 0 V to the incremental reset stop voltage ( V res,stop ) from 1.2 V (yellow) to 2.4 V (red).…”

Section: Resultsmentioning

confidence: 95%

Multimode Synaptic Operation of a HfAlO_x-Based Memristor as a Metaplastic Device for Neuromorphic Applications

Shin

Song

Kim

et al. 2022

ACS Appl. Electron. Mater.

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Metaplasticity is one of the synaptic functions in the brain, known as the plasticity of synapse plasticity. It allows some specific functions of the brain, such as continual learning, rapid homeostasis, and synaptic tag-and-capture functions. Here, we propose an electrically triggerable HfAlO x -based metaplastic device that exhibits reversible multimode synaptic behaviors. The origin of the synaptic characteristic change is the change in the serial and parallel resistance components of the memristive system, accompanied by unbalanced oxygen flux during the set and reset switching, triggered by the priming activity. Four distinguishable potentiation and depression characteristics (two stable modes and two transition modes) are suggested, which can be explained using a plausible schematic model. A hardware-based adaptive learning system for artificial neural networks is proposed as a potential application of the metaplastic device.

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Uniform and robust TiN/HfO2/Pt memristor through interfacial Al-doping engineering

Cited by 46 publications

References 37 publications

Analysis of the Thermal Degradation Effect on a HfO₂-Based Memristor Synapse Caused by Oxygen Affinity of a Top Electrode Metal and on a Neuromorphic System

Analysis of the Thermal Degradation Effect on a HfO₂-Based Memristor Synapse Caused by Oxygen Affinity of a Top Electrode Metal and on a Neuromorphic System

Structure and Electrical Properties of Zirconium-Aluminum-Oxide Films Engineered by Atomic Layer Deposition

Multimode Synaptic Operation of a HfAlO_x-Based Memristor as a Metaplastic Device for Neuromorphic Applications

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Uniform and robust TiN/HfO2/Pt memristor through interfacial Al-doping engineering

Cited by 46 publications

References 37 publications

Analysis of the Thermal Degradation Effect on a HfO2-Based Memristor Synapse Caused by Oxygen Affinity of a Top Electrode Metal and on a Neuromorphic System

Analysis of the Thermal Degradation Effect on a HfO2-Based Memristor Synapse Caused by Oxygen Affinity of a Top Electrode Metal and on a Neuromorphic System

Structure and Electrical Properties of Zirconium-Aluminum-Oxide Films Engineered by Atomic Layer Deposition

Multimode Synaptic Operation of a HfAlOx-Based Memristor as a Metaplastic Device for Neuromorphic Applications

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Analysis of the Thermal Degradation Effect on a HfO₂-Based Memristor Synapse Caused by Oxygen Affinity of a Top Electrode Metal and on a Neuromorphic System

Analysis of the Thermal Degradation Effect on a HfO₂-Based Memristor Synapse Caused by Oxygen Affinity of a Top Electrode Metal and on a Neuromorphic System

Multimode Synaptic Operation of a HfAlO_x-Based Memristor as a Metaplastic Device for Neuromorphic Applications