Investigating charge trapping in ferroelectric thin films through transient measurements

Lancaster, Suzanne; Lomenzo, Patrick D.; Engl, Moritz; Xu, Bohan; Mikolajick, Thomas; Schroeder, Uwe; Slesazeck, Stefan

doi:10.3389/fnano.2022.939822

Cited by 20 publications

(10 citation statements)

References 43 publications

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“…This is further confirmed by the analysis of the C-f/G-f curves by the smallsignal model (Fig. 3) including HZO physical properties [36], [37] (i.e., voltage dependence of HZO permittivity (𝜖 𝑟𝐹𝐸 ) and of HZO conductance (𝐺 𝐹𝐸 )), a first-order equivalent trap response and equivalent interfacial layers effect [39], [44], [45] (Cit and Git), together with the parasitic series impedance (ZSER = CSER//GSER). It is worth noting that 𝜖 𝑟𝐹𝐸 represent an equivalent contribution of the different ferroelectric and nonferroelectric phases inside the layer, together with the effect of the interfacial layers permittivity.…”

Section: Devices and Experimentssupporting

confidence: 61%

The Role of Defects and Interface Degradation on Ferroelectric HZO Capacitors Aging

Benatti

Vecchi

Pešić

et al. 2023

2023 IEEE International Reliability Physics Symposium (IRPS)

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The discovery of ferroelectricity in HfO2based materials, especially Hf0.5Zr0.5O2 (HZO), opened to a wide range of applications. In fact, innovative HZO memories, such as ferroelectric tunnel junctions (FTJs), are suitable candidates as ultra-low power storage/synaptic elements, holding the data as a polarization state. Yet, a clear link between the device degradation and material/interface properties is still lacking. In this work, we elucidate the degradation dynamics in metal-HZO-metal (MFM) capacitors by combining ab-initio calculations, physics-based simulations, dedicated experiments, and custom data analysis based on a recently introduced small-signal device model. Stress/measure experiments are conducted to: i) extract the 2𝑷 𝒓 (remnant polarization) evolution throughout device lifetime (from pristine to wake-up and fatigue); ii) determine parasitic series impedance and key material properties through a small-signal model; iii) evaluate the leakage current. Including the contribution of the parasitic series impedance in physics-based simulations allows reproducing leakage profiles and their cycling evolution. The combination of the proposed approaches allows to better interpret the behavior of these devices and retrieve the key role of process conditions (specifically post-deposition steps) in determining the device lifetime and overall reliability.

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Section: Devices and Experimentssupporting

confidence: 61%

The Role of Defects and Interface Degradation on Ferroelectric HZO Capacitors Aging

Benatti

Vecchi

Pešić

et al. 2023

2023 IEEE International Reliability Physics Symposium (IRPS)

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“…The root mean square (RMS) value of the voltage magnitude for the 100 Hz triangular waveform for voltages between 4.0 and 4.5 V (corresponding to the coercive voltages of some of the pinned domains) is 0.2885 V (=0.577 × 0.5 V). The 1 kHz square waveform RMS is 0.5 V. During switching, there is charge injection from the electrodes to charge traps (resulting in charging or discharging of the traps) and movement of oxygen vacancies under the applied field. , Since the triangular waveform has a lower RMS voltage than the square one (hence a lower electric field), both the vacancy movement and charge injection are much reduced under the triangular waveform, even though both waveforms have the electric field applied for the same duration. These mechanisms are indicated in the schematic shown in Figure S3.…”

Section: Resultsmentioning

confidence: 99%

Cycling Waveform Dependent Wake-Up and ON/OFF Ratio in Al₂O₃/Hf_0.5Zr_0.5O₂ Ferroelectric Tunnel Junction Devices

Nair

Holzer

Dubourdieu

et al. 2023

ACS Appl. Electron. Mater.

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The wake-up behavior and ON/OFF current ratio of TiN−Al 2 O 3 −Hf 0.5 Zr 0.5 O 2 −W ferroelectric tunnel junction (FTJ) devices were investigated for different wake-up voltage waveforms. We studied triangular and square waves, as well as square pulse trains of equal or unequal voltage amplitudes for positive and negative polarities. We find that the wake-up behavior in these FTJ stacks is highly influenced by the field cycling waveform. A square waveform is observed to provide wake-up with the lowest number of cycles, concomitantly resulting in higher remnant polarization and a higher ON/OFF ratio in the devices, compared to a triangular waveform. We further show that wake-up is dependent on the number of cycles rather than the total time of the applied electric field during cycling. We also demonstrate that different voltage magnitudes are necessary for positive and negative polarities during field cycling for efficient wake-up. Utilizing an optimized waveform with unequal magnitudes for the two polarities during field cycling, we achieve a reduction in wake-up cycles and a large enhancement of the ON/OFF ratio from ∼5 to ∼35 in our ferroelectric tunnel junctions.

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“…However, a slightly collapsed saturated current peak is observed for both SL 10 and SL 15 capacitors, similar to the SL 5 capacitor but significantly improved compared with HZO. Figure S4 shows the measured polarization loss of the HZO and SL FE films. − The slight polarization loss was achieved with the SL 5 structure, which proved that the SL structure can effectively inhibit the depolarization field.…”

Section: Resultsmentioning

confidence: 94%

HfO₂–ZrO₂ Ferroelectric Capacitors with Superlattice Structure: Improving Fatigue Stability, Fatigue Recovery, and Switching Speed

Kang,

Peng,

Xiao

et al. 2024

ACS Appl. Mater. Interfaces

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HfO 2 −ZrO 2 ferroelectric films have recently gained considerable attention from integrated circuit researchers due to their excellent ferroelectric properties over a wide doping range and low deposition temperature. In this work, different HfO 2 − ZrO 2 superlattice (SL) FE films with varying periodicity of HfO 2 (5 cycles)−ZrO 2 (5 cycles) (SL 5 ), HfO 2 (10 cycles)−ZrO 2 (10 cycles) (SL 10 ), and HfO 2 (15 cycles)−ZrO 2 (15 cycles) (SL 15 ) were studied systematically. The HfZrO x (HZO) alloy was used as a comparison device. The SL 5 film demonstrated improved ferroelectric properties compared to the HZO film, with the 2 times remnant polarization (2P r ) values increasing from 41.4 to 48.6 μC/cm 2 at an applied voltage of 3 V/10 kHz. Furthermore, the first-order reversal curve diagrams of different SL and HZO capacitors at different states (initial, wake-up, fatigue, and recovery) were measured. The SL capacitors were found to effectively suppress the diffusion of defects during P−V cycling, resulting in improved fatigue stability characteristics and fatigue recovery capability compared to the HZO capacitor. Moreover, an improved switching speed of the SL films compared to the HZO capacitor was concluded based on the inhomogeneous field mechanism (IFM) model. These results indicate that the SL structure has a high potential in future high-speed ferroelectric memory applications with excellent stability and recovery capability.

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Investigating charge trapping in ferroelectric thin films through transient measurements

Cited by 20 publications

References 43 publications

The Role of Defects and Interface Degradation on Ferroelectric HZO Capacitors Aging

The Role of Defects and Interface Degradation on Ferroelectric HZO Capacitors Aging

Cycling Waveform Dependent Wake-Up and ON/OFF Ratio in Al₂O₃/Hf_0.5Zr_0.5O₂ Ferroelectric Tunnel Junction Devices

HfO₂–ZrO₂ Ferroelectric Capacitors with Superlattice Structure: Improving Fatigue Stability, Fatigue Recovery, and Switching Speed

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Investigating charge trapping in ferroelectric thin films through transient measurements

Cited by 20 publications

References 43 publications

The Role of Defects and Interface Degradation on Ferroelectric HZO Capacitors Aging

The Role of Defects and Interface Degradation on Ferroelectric HZO Capacitors Aging

Cycling Waveform Dependent Wake-Up and ON/OFF Ratio in Al2O3/Hf0.5Zr0.5O2 Ferroelectric Tunnel Junction Devices

HfO2–ZrO2 Ferroelectric Capacitors with Superlattice Structure: Improving Fatigue Stability, Fatigue Recovery, and Switching Speed

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Product

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About

Cycling Waveform Dependent Wake-Up and ON/OFF Ratio in Al₂O₃/Hf_0.5Zr_0.5O₂ Ferroelectric Tunnel Junction Devices

HfO₂–ZrO₂ Ferroelectric Capacitors with Superlattice Structure: Improving Fatigue Stability, Fatigue Recovery, and Switching Speed