Failure Analysis in Magnetic Tunnel Junction Nanopillar with Interfacial Perpendicular Magnetic Anisotropy

Zhao, Weisheng; Xuan, Zhao; Zhang, Boyu; Cao, Kaihua; Wang, Lezhi; Wang, Kang; Shi, Qian; Wang, Mengxing; Zhang, Yu; Wang, You; Peng, Shouzhong; Klein, Jacques-Olivier; Naviner, Lirida de Barros; Ravelosona, D.

doi:10.3390/ma9010041

Cited by 76 publications

(49 citation statements)

References 94 publications

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“…The current density for switching of STT-MRAM is relatively large and hence large transistors are inevitable to drive it, which thus significantly limits their future use for memory applications 6,7 . The sustainability of higher switching current density of the tunnel barrier also raises reliability issues and leads to the degradation of related MTJ performance, such as, tunnel magneto resistance (TMR), write current margin, and write speed on the time span [8][9][10] . The situation will be even much worse when further scaling of STT-MRAM enters into a nanometer regime.…”

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confidence: 99%

Impact of Spin-Orbit Torque on Spin-Transfer Torque Switching in Magnetic Tunnel Junctions

Pathak

Youm

Hong

2020

Sci Rep

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the paper presents our simulated results showing the substantial improvement of both switching speed and energy consumption in a perpendicular magnetic tunnel junction (p-MTJ), a core unit of Spin-Transfer-Torque Magnetic Random Access Memory (STT-MRAM), by the help of additional Spin-Orbit-Torque (SOT) write pulse current (WP Sot ). An STT-SOT hybrid torque module for OOMMF simulation is implemented to investigate the switching behavior of a 20 nm cell in the p-MTJ. We found that the assistance of WP Sot to STT write pulse current (WP Stt ) have a huge influence on the switching behavior of the free layer in the p-MTJ. For example, we could dramatically reduce the switching time (t SW ) by 80% and thereby reduce the write energy over 70% as compared to those in the absence of the WP Sot . Even a very tiny amplitude of WP Sot (J Sot of the order of 10 2 A/m 2 ) substantially assists to reduce the critical current density for switching of the free layer and thereby decreases the energy consumption as well. It is worth to be pointed out that the energy can be saved further by tuning the WP Sot parameters, i.e., amplitude and duration along at the threshold WP Stt . Our findings show that the proposed STT-SOT hybrid switching scheme has a great impact on the MRAM technology seeking the high speed and low energy consumption.Magnetic Random Access Memory (MRAM) has known to be an outstanding candidate among next-generation memories due to its various advantages, such as non-volatility, high-speed operation, high density and scalability, over other competing memories 1-4 . In particular, spin-transfer torque MRAM (STT-MRAM) composed of perpendicular magnetic tunnel junctions (p-MTJs) has received a significant attention because it offers reduced write current and strong thermal stability 5 . In an MTJ, there are two ferromagnetic (FM) layers separated by an insulating tunneling barrier. One FM layer has a fixed magnetization and another has a variable magnetization (called as a free layer) which can be made to align either parallel (P) or anti-parallel (AP) with respect to the fixed layer. Magnetization of the free layer is used to store the data and can be switched by spin-polarized electrons (equivalently spin current) without a magnetic field. When the spin-polarized current flows through the free layer, the layer absorbs spin angular momentum from the electrons and as a result, its magnetization flips, which is the reason why we call it spin (momentum) transfer torque. STT-MRAM faces various challenges along with its merits such as, the reliability of a tunnel barrier, long write latency and small energy efficiency due to still high write current. Out of these, the most important issue which needs to be counter first is high energy consumption due to high write current and long write latency. The current density for switching of STT-MRAM is relatively large and hence large transistors are inevitable to drive it, which thus significantly limits their future use for memory applications 6,7 . The sustainability of hig...

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mentioning

confidence: 99%

Impact of Spin-Orbit Torque on Spin-Transfer Torque Switching in Magnetic Tunnel Junctions

Pathak

Youm

Hong

2020

Sci Rep

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“…The main issues that can arise during this fabrication step are: material contamination, rough surface layers, and reduced integrity of the oxide barrier. These issues can lead to a wide variation in the cell resistance and switching current [123,124].…”

Section: Defectsmentioning

confidence: 99%

Challenges and Solutions in Emerging Memory Testing

Vatajelu

Prinetto

Taouil

et al. 2019

IEEE Trans. Emerg. Topics Comput.

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International audienceThe research and prototyping of new memory technologies are getting a lot of attention in order to enable new (computer) architectures and provide new opportunities for today’s and future applications. Delivering high quality and reliability products was and will remain a crucial step in the introduction of new technologies. Therefore, appropriate fault modelling, test development and design for testability (DfT) is needed. This paper overviews and discusses the challenges and the emerging solutions in testing three classes of memories: 3D stacked memories, Resistive memories and Spin-Transfer-Torque Magnetic memories. Defects mechanisms, fault models, and emerging test solutions will be discussed

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“…For the large scale silver‐based processes, magnetron sputtering is a widely used technique because of its low cost, high‐deposition rate, and stability. It also provides relatively good yield, simple processing, and excellent thickness control over 300 mm wafer …”

Section: Introductionmentioning

confidence: 99%

“…It also provides relatively good yield, simple processing, and excellent thickness control over 300 mm wafer. 8 In case low emissivity coatings on glass, generally, thin silver layer was sandwiched between two dielectric layers such as dielectric/Ag/dielectric such as AZO/Ag/AZO. 9,10 Conductivity of Ag film correlated with optical properties has main role on emissivity of the film stacks.…”

Section: Introductionmentioning

confidence: 99%

Ag/M‐seed/AZO/glass structures for low‐E glass: Effects of metal seeds

Sönmez

Dönmez

Comert

et al. 2017

Int J of Appl Glass Sci

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In this work, continuous and conductive ultrathin Ag films with highly infrared reflective and highly visible transmittance were achieved using several metal seeds (Ti, Nb, Cr, Ni, Mo, Pt, Cu, and Ru), having ~1‐2 nm in thickness, deposited between Ag and dielectric AZO layers on glass substrate by magnetron sputtering with confocal target geometry. The optical properties in the visible and infrared ranges and conductivity of Ag/M‐seed/AZO/glass structures were compared in order to determine the influence of the seeds. It was observed that all M‐Seeds increased both visible transmittance and infrared reflectance. But also, it was shown that Nb and Ti seed layers which help on coalesced of Ag and AZO layers are more effective on the electro‐optical characteristics of the Ag thin films than the other seeds. Ag/Nb/AZO/glass and Ag/Ti/AZO/glass structures showed 2.81 and 2.84 Ω/□ sheet resistance and low surface roughness, respectively, which are the best film structures. In addition, these films have homogeneous and defect‐free surfaces that do not cause any electrical breakdown. Besides, Nb and Ti seeded structures have the low‐emissivity both 780‐2500 nm and long wavelength (λ > 3 μm) spectral region as 0.0357 and 0.0361, respectively.

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Failure Analysis in Magnetic Tunnel Junction Nanopillar with Interfacial Perpendicular Magnetic Anisotropy

Cited by 76 publications

References 94 publications

Impact of Spin-Orbit Torque on Spin-Transfer Torque Switching in Magnetic Tunnel Junctions

Impact of Spin-Orbit Torque on Spin-Transfer Torque Switching in Magnetic Tunnel Junctions

Challenges and Solutions in Emerging Memory Testing

Ag/M‐seed/AZO/glass structures for low‐E glass: Effects of metal seeds

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