Current Status and Future Challenge of Embedded High-speed MRAM

Fukami, Shunsuke; Suzuki, Takenobu; Nagahara, K.; Ohshima, Norikazu; Saitoh, Shinichi; Nebashi, R.; Sakimura, N.; Honjo, Haruo; Mori, Kazuhisa; Kariyada, Eiji; Kato, Yoshiaki; Suemitsu, Katsumi; Tanigawa, Hiroshi; Kinoshita, K.; Ishiwata, N.; Sugibayashi, Toshio

doi:10.7567/ssdm.2010.e-7-1

Cited by 3 publications

(3 citation statements)

References 5 publications

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“…Requirements for tightly controlled DW propagation pathways, the ability to use current to drive wall motion and the need to integrate storage and spintronic devices [73,74] into miniaturised electronic circuits means that wall motion must be understood not only in continuous films (the focus of this article up until this point), but also in nanostrip geometries wherein the wall moves back and forward along a patterned ferromagnetic strip.…”

Section: Field-driven Motion In Confined Geometriesmentioning

confidence: 99%

Universal magnetic domain wall dynamics in the presence of weak disorder

Ferré

Metaxas

Mougin

et al. 2013

Comptes Rendus. Physique

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The motion of elastic interfaces in disordered media is a broad topic relevant to many branches of physics. Field-driven magnetic domain wall motion in ultrathin ferromagnetic Pt/Co/Pt films can be well interpreted within the framework of theories developed to describe elastic interface dynamics in the presence of weak disorder. Indeed, the three theoretically predicted dynamic regimes of creep, depinning, and flow have all been directly evidenced in this model experimental system. We discuss these dynamic regimes and demonstrate how field-driven creep can be controlled not only by temperature and pinning, but also via interactions with magnetic entities located inside or outside the magnetic layer. Consequences of confinement effects in nano-devices are briefly reviewed, as some recent results on domain wall motion driven by an electric current or assisted by an electric field. Finally new theoretical developments and perspectives are discussed.

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Section: Field-driven Motion In Confined Geometriesmentioning

confidence: 99%

Universal magnetic domain wall dynamics in the presence of weak disorder

Ferré

Metaxas

Mougin

et al. 2013

Comptes Rendus. Physique

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“…pin-transfer torque (STT) in MgO-based magnetic tunnel junctions (MTJs) 1,2) is under development for device applications such as STT random access memories (STT-RAM), 3,4) domain-wall-motion MRAM, 5) racetrack memory 6) and spintronic memristors. 7,8) Recently, spin-torque diodes 9) have attracted much attention because their sensitivity for the detection of microwave frequency may exceed that of semiconductor diodes.…”

mentioning

confidence: 99%

Spin-Torque Diode Measurements of MgO-Based Magnetic Tunnel Junctions with Asymmetric Electrodes

Matsumoto

Chanthbouala

Grollier

et al. 2011

Appl. Phys. Express

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We present a detailed study of the spin-torque diode effect in CoFeB/MgO/CoFe/NiFe magnetic tunnel junctions. From the evolution of the resonance frequency with magnetic field at different angles, we clearly identify the free-layer mode and find an excellent agreement with simulations by taking into account several terms for magnetic anisotropy. Moreover, we demonstrate the large contribution of the out-of-plane torque in our junctions with asymmetric electrodes compared to the in-plane torque. Consequently, we provide a way to enhance the sensitivity of these devices for the detection of microwave frequency.Spin-transfer torque (STT) in MgO-based magnetic tunnel junctions (MTJs) [1,2] is under development for device applications such as STT random access memories (STT-RAM) [3,4], domain-wall-motion MRAM, [5] racetrack memory [6] and spintronic memristors. [7,8] Recently, spin-torque diodes [9] have attracted much attention because their sensitivity for the detection of microwave frequency may exceed that of semiconductor diodes. [10,11] In the spin diode effect, an applied rf current to the MTJ exerts an oscillating spin torque on the magnetization of the free layer, leading to excitation of the ferromagnetic resonance (FMR) mode. The dynamics of the free layer cause oscillations of the tunnel magnetoresistance (TMR). As a result, the oscillating resistance partially rectifies the rf current and dc voltage is obtained (V diode ). The spin diode effect depends on the relative amplitudes (a J and b J ) of the classical inplane torque (T IP ) and the out-of-plane field-like torque (T OOP ). [12,13] Here, the torques are expressed as T IP = -γ(a J /M s )m×(m×M ref ) and T OOP = -γb J m×M ref with m (M s ) being the magnetization vector (the saturation magnetization) of the free layer, M ref the magnetization vector of the reference layer, and γ the gyromagnetic ratio. In spin diode spectra (V diode as a function of frequency (f )), the contribution of T IP (resp. T OOP ) results in a peak with a Lorentzian component (resp. an anti-Lorentzian component);where A and B are the amplitudes of the anti-Lorentzian component and Lorentzian component, f 1 is the resonance frequency, ∆ is the peak linewidth, H d is the outof-plane demagnetization field, and θ is the relative angle between the free layer and the reference layer. Experimentally evaluated T OOP was reported to reach over 25% of T IP in conventional CoFeB/MgO/CoFeB MTJs with symmetric electrodes. [12,13] However, in these MTJs, the dc bias dependence of T OOP is quadratic and symmetric with respect to the polarity of bias, leading to A = 0 at zero dc bias voltage. For MTJs with asymmetric electrodes, on the other hand, the bias dependence of T OOP is expected to be asymmetric and linear at low bias, [15,16] leading to larger A at zero dc bias voltage. In this study, we perform spin diode measurements of MgO-based MTJs with asymmetric electrodes. We also measure its dependence on magnitude and angle of the in-plane external magnetic field (H ext ) to identify the...

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“…Owing to the emergence of copper interconnects, a corrosion protection technique becomes especially essential because Cu is easily dissolved in process solutions, such as an etching solvent, the slurry of chemical mechanical planarization (CMP), and so on. Moreover, backends of line (BEOL)-based memory applications, for example, magnetic random access memory (MRAM), 1) phase-change random access memory (PRAM), 2) and resistance random access memory (RRAM or ReRAM), 3) are currently being developed and reported. Thus, it is more important to understand the corrosion mechanism since corrosion in interconnects can easily spread to other attached structures of MRAM, PRAM, or RRAM that are composed of metal or conductive materials.…”

Section: Background Of Corrosion Studymentioning

confidence: 99%

Potential Characterization of Interconnect Corrosion by Kelvin Probe and Electrostatic Force Microscopies

Kodera

Yoshimizu

Uchida

2012

Jpn. J. Appl. Phys.

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The fine-scale potential observation was performed by Kelvin probe force microscopy (KFM) and electrostatic force microscopy (EFM) using tungsten interconnects in which the minimum width was 43 nm. It was confirmed that the line connected to pads and/or a transistor has a peculiar KFM potential by comparing it with the surrounding pattern. Only the plugs attached to this line were corroded, while the other plugs remained intact. By comparing the results of KFM and EFM observations, the peculiar potential of the line can be attributed to the electron charge up in the bulk of the sample. Charged electrons induced corrosion not only in the line itself but also in the connected structure. It was also revealed that the particular potential can be suppressed by a wet treatment.

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Current Status and Future Challenge of Embedded High-speed MRAM

Cited by 3 publications

References 5 publications

Universal magnetic domain wall dynamics in the presence of weak disorder

Universal magnetic domain wall dynamics in the presence of weak disorder

Spin-Torque Diode Measurements of MgO-Based Magnetic Tunnel Junctions with Asymmetric Electrodes

Potential Characterization of Interconnect Corrosion by Kelvin Probe and Electrostatic Force Microscopies

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