Performance of write-line inserted magnetic tunneling junction for low-write-current magnetic random access memory cell

Honjo, H.; Nebashi, R.; Suzuki, T.; Fukami, Shunsuke; Ishiwata, N.; Sugibayashi, Toshio; Kasai, N.

doi:10.1063/1.2839288

Cited by 11 publications

(8 citation statements)

References 5 publications

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“…We have already developed an MRAM process for a 2T1MTJ MRAM cell as well as a 1-Mbit MRAM macro [5][6]. This process is unique and more suitable for high speed (e.g.…”

Section: Introductionmentioning

confidence: 99%

Nonvolatile Magnetic Flip-Flop for standby-power-free SoCs

Sakimura

Sugibayashi

Nebashi

et al. 2008

2008 IEEE Custom Integrated Circuits Conference

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A nonvolatile Magnetic Flip-Flop (MFF) primitive cell for SoC design libraries has been developed using a unique MRAM process. It has high design compatibility with conventional CMOS LSI designs. MFF maximum frequency was estimated to be 3.5 GHz, which is comparable to that of a normal CMOS DFF. An MFF test chip was fabricated with the process. The chip's functional performance was sufficiently high to demonstrate the potential of MFFs, which helps to reduce the power dissipation of SoCs dramatically.

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“…We have already developed an MRAM process for a 2T1MTJ MRAM cell as well as a 1-Mbit MRAM macro [5][6]. This process is unique and more suitable for high speed (e.g.…”

Section: Introductionmentioning

confidence: 99%

Nonvolatile Magnetic Flip-Flop for standby-power-free SoCs

Sakimura

Sugibayashi

Nebashi

et al. 2008

2008 IEEE Custom Integrated Circuits Conference

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“…5 The patterning process for SFF consisted of two steps: first, the FL1 was patterned and the FL2 was patterned after that. A MTJ without FL3 was fabricated on the same wafer as a reference.…”

Section: Methodsmentioning

confidence: 99%

“…The H sw of SVM with FL3 was higher than that of SVM without FL3 because FL2 and FL3 were magnetostatically coupled. 5 The magnetostatic coupling field between FL2 and FL3 increased as the thicknesses of FL2 and FL3 increased. This increase was balanced to decrease in anisotropy of the SFF.…”

Section: B Switching Properties Created By Magnetic Fieldmentioning

confidence: 98%

“…A write-line-inserted MTJ ͑WLIM͒ with magnetic field-induced switching for the cell of the one-axis writing scheme was demonstrated, and its write current was reduced to 0.98 mA, although the MR ratio of 30% was relatively low. 5 We have further proposed a shape-varying MTJ ͑SVM͒. 6 The SVM structure led to both a low write current and a high MR ratio.…”

Section: Introductionmentioning

confidence: 99%

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Performance of shape-varying magnetic tunneling junction for high-speed magnetic random access memory cells

Honjo

Fukami

Nebashi

et al. 2009

Journal of Applied Physics

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We have developed a shape-varying magnetic tunneling junction ͑MTJ͒ ͑SVM͒ which has a high MR ratio and low write current for use in high-speed magnetic random access memory ͑MRAM͒ cells. Combining NiFe that has low anisotropy to CoFeB which has high anisotropy through the nonmagnetic layer by interlayer exchange coupling ͑synthetic ferromagnetic coupling free layer: SFF͒, the anisotropy of SFF was reduced much more than that of CoFeB, and the MR ratio was improved much more than that of NiFe. The switching magnetic field ͑H sw ͒ of SFF was reduced as the thickness of NiFe increased. The H sw of SFF for 0.24ϫ 0.48 m 2 MTJ was 30 Oe when the thickness of CoFeB was 1.5 nm and that of NiFe was 3.0 nm. Furthermore H sw was reduced to 18 Oe by varying the shape of the MTJ of NiFe to 0.48ϫ 0.48 m 2 ; the shape of the MTJ of CoFeB was not changed ͑0.24ϫ 0.48 m 2 ͒. Combining the SVM and a write-line-inserted structure, we obtained a write current of 0.9 mA and an MR ratio of 140%. The H sw was 40 Oe and its thermal stability factor was 82. These properties are sufficient for operating MRAMs over 500 MHz.

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“…[8][9][10] We previously proposed a shape-varying MTJ (SVM), 11 which switched by magnetic field, as a three-terminal cell. 12,13 This cell is not scalable, however, the switching current of under 1 mA was enough small to demonstrate logic circuit. The MR ratio of the SVM in which the CoFeB film was used as a free layer was high enough, however, it had a big switching current distribution because of the large intrinsic anisotropy of CoFeB.…”

Section: Introductionmentioning

confidence: 99%

Magnetic tunneling junction with Fe/NiFeB free layer for magnetic logic circuits

Honjo¹,

Fukami

Nebashi³

et al. 2012

Journal of Applied Physics

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We have developed a shape varying magnetic tunneling junction (SVM) with a Fe/NiFeB free layer for use in magnetic logic circuits. Inserting the thin Fe film between an NiFeB free layer and MgO tunneling barrier improved the magnetoresistance (MR) ratio: it increased up to 130%, as the thickness of the Fe film increased. In addition, the switching current distribution of the SVM was reduced to 8%. By using NiFeB as a free layer, the roughness under the MgO was reduced and the crystallization of the MgO was enhanced. This led to both the high MR ratio and the low switching current distribution. Our developed Fe (0.4 nm)/NiFeB free layer satisfies the requirement of the MTJ's characteristics that the magnetic logic circuits operate with a high bit yield.

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Performance of write-line inserted magnetic tunneling junction for low-write-current magnetic random access memory cell

Cited by 11 publications

References 5 publications

Nonvolatile Magnetic Flip-Flop for standby-power-free SoCs

Nonvolatile Magnetic Flip-Flop for standby-power-free SoCs

Performance of shape-varying magnetic tunneling junction for high-speed magnetic random access memory cells

Magnetic tunneling junction with Fe/NiFeB free layer for magnetic logic circuits

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