Advanced MTJ Stack Engineering of STT-MRAM to Realize High Speed Applications

Lee, T. Y.; Yamane, K.; Otani, Y.; Zeng, D.; Kwon, Jae Hyun; Lim, J. H.; Naik, V. B.; Hau, L. Y.; Ren, Chao; Chung, N. L.; Ling, T.; Jang, Seonhee; Goh, L. C.; Hwang, J.; Zhang, L.; Löw, Robert; Balasankaran, N.; Tan, Funan; Ting, J. W.; Chang, Ji‐Eun; Seet, C. S.; Ong, Shao Jin; You, Yuan; Woo, S. T.; Chan, T. H.; Siah, S. Y.

doi:10.1109/iedm13553.2020.9372015

Cited by 13 publications

(9 citation statements)

References 4 publications

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“…STT-MRAM technology is considered to be the most viable solution owing to its attractive properties such as CMOS process compatibility, high operation speeds, superior endurance, and negligible leakage, thus, making it an ideal solution for low power, embedded electronics [1][2][3]. Significant resources have been invested in the past decade at major foundries and tool suppliers to optimize this technology for last-level cache (LLC) memory, microcontroller units (MCU), eFLASH, and automotive applications [2,[4][5][6][7][8][9][10][11][12]. Despite these excellent advancements, some challenges remain.…”

Section: Introductionmentioning

confidence: 99%

A Systematic Assessment of W-Doped CoFeB Single Free Layers for Low Power STT-MRAM Applications

et al. 2021

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Spin-transfer torque magnetoresistive random access memory (STT-MRAM) technology is considered to be the most promising nonvolatile memory (NVM) solution for high-speed and low power applications. Dual MgO-based composite free layers (FL) have driven the development of STT-MRAMs over the past decade, achieving data retention of 10 years at the cost of higher write power consumption. In addition, the need for tunnel magnetoresistance (TMR)-based read schemes limits the flexibility in materials beyond the typical CoFeB/MgO interfaces. In this study, we propose a novel spacerless FL stack comprised of CoFeB alloyed with heavy metals such as tungsten (W) which allows effective modulation of the magnet properties (Ms, Hk) while retaining compatibility with MgO layers. The addition of W results favours a delayed crystallization process, in turn enabling higher thermal budgets up to 180 min at 400 °C. The presence of tungsten reduces the total FL magnetization (Ms) but simultaneously increasing its temperature dependence, thus, enabling a dynamic write current reduction of ~15% at 2 ns pulse widths. Reliable operation is demonstrated with a WER of 1 ppm and endurance >1010 cycles. These results pave the way for alternative designs of STT-MRAMs for low power electronics.

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Section: Introductionmentioning

confidence: 99%

A Systematic Assessment of W-Doped CoFeB Single Free Layers for Low Power STT-MRAM Applications

et al. 2021

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“…The authors would like to acknowledge Everspin Technologies, 1 Chandler, AZ, USA, for their technical expertise in the fabrication of the devices used in this work.…”

Section: Acknowledgmentmentioning

confidence: 99%

“…S PIN-TRANSFER torque magnetoresistive random access memory (STT-MRAM) has shown great potential as a replacement for SRAM cache due to its low latency [1] and for embedded Flash due to its high endurance, retention, and favorable form factor [2]. The principle behind the operation of STT-MRAM is the reversible flipping of magnetic spins in the free layer (FL) relative to magnetization in the reference layer (RL) using current density in a range of 5-7 MA/cm 2 .…”

Section: Introductionmentioning

confidence: 99%

Impact of Voltage Polarity on Time-Dependent Dielectric Breakdown of 1-nm MgO-Based STT-MRAM With Self-Heating Correction

Tan

Lim

Sikder

et al. 2023

IEEE Trans. Electron Devices

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Time-dependent dielectric breakdown (TDDB) lifetime of ultrathin (1 nm) MgO in spin-transfer torque magnetoresistive random access memory (STT-MRAM) devices has recently been shown to be driven by factors other than voltage alone. This study focuses on the specific role of asymmetry in the current flow for different polarity pulsing modes of voltage stress on the TDDB lifetime of 1-nm MgO. Numerical analysis, based on a 3-D heat-diffusion equation and spintronic simulations, has been performed to characterize the temperature rise in the devices for precise correction of self-heating to obtain a correct interpretation of MgO TDDB. It is shown that the different lifetimes for the positive and negative modes can be attributed to different temperature increases arising from self-heating. While the positive and negative modes displayed a non-Arrhenius behavior, the bipolar mode showed an Arrhenius trend in which we observed a unique bimodal behavior of TDDB activation energy (E a ) as a function of stress voltage in the ultrathin MgO stack. We discuss the role of additional driving forces, such as current, self-heating, charge trapping, and interface strain governing the breakdown mechanism along with the voltage effect.

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“…Besides, the two-terminal tunneling junction memristor (TJM) is another kind of promising device candidate in nextgeneration memories, owing to its attractive advantages, such as high density data storage, fast access speed, and low power consumption [6,7]. Among various nonvolatile TJMs, the ferroelectric tunneling junction (FTJ) exploiting the polarization-dependent tunneling electroresistance (TER) effect has specifically attracted much attention [8,9].…”

Section: Intoductionmentioning

confidence: 99%

Performance improvement of a tunnel junction memristor with amorphous insulator film

et al. 2023

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This study theoretically demonstrated the oxygen vacancy (VO2+)-based modulation of a tunneling junction memristor (TJM) with a high and tunable tunneling electroresistance (TER) ratio. The tunneling barrier height and width are modulated by the VO2+-related dipoles, and the ON and OFF-state of the device are achieved by the accumulation of VO2+ and negative charges near the semiconductor electrode, respectively. Furthemore, the TER ratio of TJMs can be tuned by varying the density of the ion dipoles (Ndipole), thicknesses of ferroelectric-like film (TFE) and SiO2 (Tox), doping concentration (Nd) of the semiconductor electrode, and the workfunction of the top electrode (TE). An optimized TER ratio can be achieved with high oxygen vacancy density, relatively thick TFE, thin Tox, small Nd, and moderate TE workfunction.

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Advanced MTJ Stack Engineering of STT-MRAM to Realize High Speed Applications

Cited by 13 publications

References 4 publications

A Systematic Assessment of W-Doped CoFeB Single Free Layers for Low Power STT-MRAM Applications

A Systematic Assessment of W-Doped CoFeB Single Free Layers for Low Power STT-MRAM Applications

Impact of Voltage Polarity on Time-Dependent Dielectric Breakdown of 1-nm MgO-Based STT-MRAM With Self-Heating Correction

Performance improvement of a tunnel junction memristor with amorphous insulator film

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