Demonstration of Fatigue and Recovery Phenomena in Hf0.5Zr0.5O2-based 1T1C FeRAM Memory Arrays

Okuno, Junko; Yonai, Tsubasa; Kunihiro, Takafumi; Konishi, Kenta; Materano, Monica; Ali, Tarek; Lederer, Maximilian; Seidel, Konrad; Mikolajick, Thomas; Schroeder, Uwe; Tsukamoto, Masanori; Umebayashi, Taku

doi:10.1109/edtm53872.2022.9797943

Cited by 5 publications

(5 citation statements)

References 3 publications

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“…Furthermore, positively charged oxygen vacancies formed by electron de-trapping at the interface between HZO and electrodes can cause domain pinning, and the fatigue can be recovered by applying a high stress field [18], [19]. Previously, we have revealed that the fatigue and recovery phenomenon are caused by the uniform usage of 64-kbits of 1T1C FeRAM memory array with Hf0.5Zr0.5O2-based capacitors under a fatigue stress condition of 2.0 V at 10 MHz and recovery stress condition of 2.8 V at 10 MHz [20]. In this paper, we have extended our prior work and performed a detailed analysis using a single large capacitor that was fabricated using a same process to 1T1C FeRAM to clearly understand the recovery mechanism and comprehensively investigate the recovery effect.…”

Section: Introductionmentioning

confidence: 99%

“…(a) Fatigue measurement result up to 10 10 cycles with a cycling stress voltage of 2.0 V and the pulse width of 100 ns (b) Recovery test result of 10 10 cycles with a cycling stress voltage of 2.8 V and the pulse width of 100 ns, and (c) Re-fatigue test results for 10 10 cycles post recovery with a cycling stress voltage of 2.0 V and the pulse width of 100 ns. Median value of ΔVBL (Bitline voltage shift of the 1T1C FeRAM) in 4 kbits MFM cells are extracted [20].…”

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confidence: 99%

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Investigation of Recovery Phenomena in Hf_0.5Zr_0.5O₂-Based 1T1C FeRAM

Okuno¹,

Yonai²,

Kunihiro³

et al. 2023

IEEE J. Electron Devices Soc.

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We have previously studied fatigue and its recovery phenomenon on 64 kbits hafnium-based one-transistor and onecapacitor (1T1C) ferroelectric random-access memory (FeRAM) with PVD-TiN (30 nm)/ALD-Hf0.5Zr0.5O2 (8 nm)/CVD-TiN (50 nm) capacitors. In this study, we characterized a single large capacitor fabricated using the same process as the 1T1C FeRAM to clearly understand the recovery mechanism and comprehensively qualify the recovery effect. The results reveal that the recovery effect is caused by domain depinning and new domains switching owing to a redistribution of oxygen vacancy. Furthermore, it is evident from recovery voltage and recovery pulse width dependence of the recovery effect that the recovery voltage can be reduced by applying a longer recovery pulse width. This enables a more flexible circuit design of 1T1C FeRAM when the recovery method is applied to enhance the cycling endurance.

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Investigation of Recovery Phenomena in Hf_0.5Zr_0.5O₂-Based 1T1C FeRAM

Okuno¹,

Yonai²,

Kunihiro³

et al. 2023

IEEE J. Electron Devices Soc.

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“…Hafnium zirconium oxide (HZO) is the promising material of choice due to its CMOS process compatibility, large coercive field, and robust ferroelectric properties even in films lower than 10nm thick [2]. The ferroelectric memories, including ferroelectric random-access memories (FeRAM) [3], ferroelectric field effect transistors (FeFET) [4], and ferroelectric tunneling junctions (FTJ) [5] can be used to store data by retaining remanent polarization (Pr) even without applied voltage [6]. Since the ferroelectric properties come from the formation of orthorhombic phase (ophase) in the HZO film [6], the ability to identify the o-phase crystal is critical for developing ferroelectric memories.…”

Section: Introductionmentioning

confidence: 99%

“…are purely schematic, and the activation barriers are not proportionally graphed. Since the activation barrier between tphase and m-phase (~9.03eV/nm 3 ) is so much higher than activation barrier between o-phase and t-phase (~0.788eV/nm 3 ), the difference of Gibbs free energy between t-phase and ophase (~1.6 eV/nm 3 at room temperature, ~0.2 eV/nm 3 at 400 o C, ~0.1 eV/nm 3 at 500 o C, and ~-0.2 eV/nm 3 at 800 o C), and the difference of Gibbs free energy between t-phase and m-phase (~1.9 eV/nm 3 at room temperature, ~0.5 eV/nm3 at 400 o C, ~0.4 eV/nm 3 at 500 o C, and ~0.1 eV/nm 3 at 800 o C), a free energy diagram with proportionally scaled activation barriers cannot convey our ideas clearly. During the annealing step, amorphous HZO crystallizes into the o-phase, t-phase, and m-phase crystals (Figure.…”

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confidence: 99%

A Kinetic Pathway to Orthorhombic HfZrO

Chen,

Zhao

et al. 2023

IEEE J. Electron Devices Soc.

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To improve the crystallinity and phase composition of the Hf0.5Zr0.5O2 films, the effects of annealing temperature on metal-ferroelectric-metal devices are studied by electrical measurements, nanobeam electron diffraction (NBD), and TEM. Forming gas annealing (FGA) at 400 o C partially crystallizes the films, and more crystallization can be achieved by FGA at the increasing temperature of 500 o C and 800 o C. After FGA at 400 o C and 500 o C, metastable ferroelectric orthorhombic phase can be obtained as shown by electrical measurements and NBD. By the density functional theory (DFT) simulation, we propose that o-phase formation happens during both the annealing step as well as the cooling step. During the FGA at 800 o C, the metastable orthorhombic phase overcomes the activation barrier and transforms into stable monoclinic phase. In this work, the systematic experimental study of phase transformation, free energy simulation for different phases, and schematic diagrams of free energy for phase transition at different temperatures are reported.

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“…One such approach is the development of novel devices, with new types of memories being a critical direction. Hafnium-based ferroelectric memory stands out as a promising candidate among these emerging memory technologies [1][2][3][4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Methodology for Testing Key Parameters of Array-Level Small-Area Hafnium-Based Ferroelectric Capacitors Using Time-to-Digital Converter and Capacitance Calibration Circuits

Zhang,

Yang,

Cao

et al. 2023

Micromachines

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Hafnium-based ferroelectric memories are a promising approach to enhancing integrated circuit performance, offering advantages such as miniaturization, compatibility with CMOS technology, fast read and write speeds, non-volatility, and low power consumption. However, FeRAM (Ferroelectric Random Access Memory) still faces challenges related to endurance and retention susceptibility to process variations. Hence, testing and obtaining the core parameters of ferroelectric capacitors continuously is essential to investigate these phenomena and explore the potential solution. The traditional method for measuring ferroelectric capacitors has limitations in timing generation capability, introduces parasitic capacitance, and lacks accuracy for small-area capacitors. In this study, we analyzed the working principle of ferroelectric capacitors and designed a method to detect the remnant polarization, saturation polarization, and imprint offset of ferroelectric capacitors. Further, we further proposed a circuit implementation method. The proposed test circuit conquers these limitations and enables high-precision testing of ferroelectric capacitors, contributing to developing hafnium-based ferroelectric memories. The circuit includes a flip-readout circuit, a capacitance calibration circuit, and a voltage-to-time converter and time-to-digital converter (VTC&TDC) readout circuit. According to simulation results, the capacitance calibration circuit reduces the deviation of the capacitance by 84%, and the accuracy of the readout circuit is 5.91 bits, with a readout time of 150 ns and a power consumption of 1 mW. This circuit enables low-cost acquisition of array-level small-area ferroelectric capacitance data, which can guide subsequent device optimization and circuit design.

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Demonstration of Fatigue and Recovery Phenomena in Hf_0.5Zr_0.5O₂-based 1T1C FeRAM Memory Arrays

Cited by 5 publications

References 3 publications

Investigation of Recovery Phenomena in Hf_0.5Zr_0.5O₂-Based 1T1C FeRAM

Investigation of Recovery Phenomena in Hf_0.5Zr_0.5O₂-Based 1T1C FeRAM

A Kinetic Pathway to Orthorhombic HfZrO

Methodology for Testing Key Parameters of Array-Level Small-Area Hafnium-Based Ferroelectric Capacitors Using Time-to-Digital Converter and Capacitance Calibration Circuits

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Demonstration of Fatigue and Recovery Phenomena in Hf0.5Zr0.5O2-based 1T1C FeRAM Memory Arrays

Cited by 5 publications

References 3 publications

Investigation of Recovery Phenomena in Hf0.5Zr0.5O2-Based 1T1C FeRAM

Investigation of Recovery Phenomena in Hf0.5Zr0.5O2-Based 1T1C FeRAM

A Kinetic Pathway to Orthorhombic HfZrO

Methodology for Testing Key Parameters of Array-Level Small-Area Hafnium-Based Ferroelectric Capacitors Using Time-to-Digital Converter and Capacitance Calibration Circuits

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Demonstration of Fatigue and Recovery Phenomena in Hf_0.5Zr_0.5O₂-based 1T1C FeRAM Memory Arrays

Investigation of Recovery Phenomena in Hf_0.5Zr_0.5O₂-Based 1T1C FeRAM

Investigation of Recovery Phenomena in Hf_0.5Zr_0.5O₂-Based 1T1C FeRAM