Improvement of Thermal Tolerance of CoFeB-MgO Perpendicular-Anisotropy Magnetic Tunnel Junctions by Controlling Boron Composition

H. Honjo; S. Ikeda; H. Sato; S. Sato; T. Watanabe; S. Miura; T. Nasuno; Y. Noguchi; M. Yasuhira; T. Tanigawa; H. Koike; M. Muraguchi; M. Niwa; K. Ito; H. Ohno; T. Endoh

doi:10.1109/TMAG.2016.2518203

Improvement of Thermal Tolerance of CoFeB-MgO Perpendicular-Anisotropy Magnetic Tunnel Junctions by Controlling Boron Composition

H. Honjo, S. Ikeda, H. Sato, S. Sato, T. Watanabe, S. Miura, T. Nasuno, Y. Noguchi, M. Yasuhira, T. Tanigawa, H. Koike, M. Muraguchi, M. Niwa, K. Ito, H. Ohno, T. Endoh

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16 Citations (Scopus)

Abstract

We investigated annealing temperature $T-{a}$ dependence of tunnel magnetoresistance (TMR) ratio and magnetic properties for perpendicular-anisotropy (CoFe)_100-XB_X/MgO magnetic tunnel junctions (MTJs) with single (CoFe)_100-XB_X/MgO interface (s-MTJ) and double CoFeB-MgO interface (d-MTJ) structures with various boron compositions X. High TMR ratio over 100% was observed in the s-MTJ with X=35 at.% after annealing at 360 °C-400 °C, whereas the s-MTJ with X=30 at.% showed the degradation of TMR ratio with the increase of T_a above 360 °C, resulting from the decrease of perpendicular anisotropy. The d-MTJ with X=25 at.% maintained high TMR ratio up to T_a = 400°C owing to its higher perpendicular anisotropy compared with the s-MTJ. The difference of perpendicular anisotropy between the s-MTJ and the d-MTJ can be attributed to higher interfacial anisotropy together with lower saturation magnetization of the d-MTJs. The lower saturation magnetization is attributable to two MgO layers that suppress boron diffusion from CoFeB layers, which was verified by cross-sectional line analysis using electron energy-loss spectroscopy.

Original language	English
Article number	7383297
Journal	IEEE Transactions on Magnetics
Volume	52
Issue number	7
DOIs	https://doi.org/10.1109/TMAG.2016.2518203
Publication status	Published - 2016 Jul

Keywords

CoFeB-MgO
magnetic tunnel junction
STT-MRAM

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10.1109/TMAG.2016.2518203

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Honjo, H., Ikeda, S., Sato, H., Sato, S., Watanabe, T., Miura, S., Nasuno, T., Noguchi, Y., Yasuhira, M., Tanigawa, T., Koike, H., Muraguchi, M., Niwa, M., Ito, K., Ohno, H., & Endoh, T. (2016). Improvement of Thermal Tolerance of CoFeB-MgO Perpendicular-Anisotropy Magnetic Tunnel Junctions by Controlling Boron Composition. IEEE Transactions on Magnetics, 52(7), Article 7383297. https://doi.org/10.1109/TMAG.2016.2518203

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title = "Improvement of Thermal Tolerance of CoFeB-MgO Perpendicular-Anisotropy Magnetic Tunnel Junctions by Controlling Boron Composition",

abstract = "We investigated annealing temperature $T-{a}$ dependence of tunnel magnetoresistance (TMR) ratio and magnetic properties for perpendicular-anisotropy (CoFe)100-XBX/MgO magnetic tunnel junctions (MTJs) with single (CoFe)100-XBX/MgO interface (s-MTJ) and double CoFeB-MgO interface (d-MTJ) structures with various boron compositions X. High TMR ratio over 100% was observed in the s-MTJ with X=35 at.% after annealing at 360 °C-400 °C, whereas the s-MTJ with X=30 at.% showed the degradation of TMR ratio with the increase of Ta above 360 °C, resulting from the decrease of perpendicular anisotropy. The d-MTJ with X=25 at.% maintained high TMR ratio up to Ta = 400°C owing to its higher perpendicular anisotropy compared with the s-MTJ. The difference of perpendicular anisotropy between the s-MTJ and the d-MTJ can be attributed to higher interfacial anisotropy together with lower saturation magnetization of the d-MTJs. The lower saturation magnetization is attributable to two MgO layers that suppress boron diffusion from CoFeB layers, which was verified by cross-sectional line analysis using electron energy-loss spectroscopy.",

keywords = "CoFeB-MgO, magnetic tunnel junction, STT-MRAM",

author = "H. Honjo and S. Ikeda and H. Sato and S. Sato and T. Watanabe and S. Miura and T. Nasuno and Y. Noguchi and M. Yasuhira and T. Tanigawa and H. Koike and M. Muraguchi and M. Niwa and K. Ito and H. Ohno and T. Endoh",

note = "Publisher Copyright: {\textcopyright} 2016 IEEE.",

year = "2016",

month = jul,

doi = "10.1109/TMAG.2016.2518203",

language = "English",

volume = "52",

journal = "IEEE Transactions on Magnetics",

issn = "0018-9464",

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Honjo, H , Ikeda, S, Sato, H, Sato, S, Watanabe, T, Miura, S, Nasuno, T, Noguchi, Y, Yasuhira, M, Tanigawa, T, Koike, H, Muraguchi, M, Niwa, M, Ito, K, Ohno, H & Endoh, T 2016, 'Improvement of Thermal Tolerance of CoFeB-MgO Perpendicular-Anisotropy Magnetic Tunnel Junctions by Controlling Boron Composition', IEEE Transactions on Magnetics, vol. 52, no. 7, 7383297. https://doi.org/10.1109/TMAG.2016.2518203

TY - JOUR

T1 - Improvement of Thermal Tolerance of CoFeB-MgO Perpendicular-Anisotropy Magnetic Tunnel Junctions by Controlling Boron Composition

AU - Honjo, H.

AU - Ikeda, S.

AU - Sato, H.

AU - Sato, S.

AU - Watanabe, T.

AU - Miura, S.

AU - Nasuno, T.

AU - Noguchi, Y.

AU - Yasuhira, M.

AU - Tanigawa, T.

AU - Koike, H.

AU - Muraguchi, M.

AU - Niwa, M.

AU - Ito, K.

AU - Ohno, H.

AU - Endoh, T.

PY - 2016/7

Y1 - 2016/7

N2 - We investigated annealing temperature $T-{a}$ dependence of tunnel magnetoresistance (TMR) ratio and magnetic properties for perpendicular-anisotropy (CoFe)100-XBX/MgO magnetic tunnel junctions (MTJs) with single (CoFe)100-XBX/MgO interface (s-MTJ) and double CoFeB-MgO interface (d-MTJ) structures with various boron compositions X. High TMR ratio over 100% was observed in the s-MTJ with X=35 at.% after annealing at 360 °C-400 °C, whereas the s-MTJ with X=30 at.% showed the degradation of TMR ratio with the increase of Ta above 360 °C, resulting from the decrease of perpendicular anisotropy. The d-MTJ with X=25 at.% maintained high TMR ratio up to Ta = 400°C owing to its higher perpendicular anisotropy compared with the s-MTJ. The difference of perpendicular anisotropy between the s-MTJ and the d-MTJ can be attributed to higher interfacial anisotropy together with lower saturation magnetization of the d-MTJs. The lower saturation magnetization is attributable to two MgO layers that suppress boron diffusion from CoFeB layers, which was verified by cross-sectional line analysis using electron energy-loss spectroscopy.

AB - We investigated annealing temperature $T-{a}$ dependence of tunnel magnetoresistance (TMR) ratio and magnetic properties for perpendicular-anisotropy (CoFe)100-XBX/MgO magnetic tunnel junctions (MTJs) with single (CoFe)100-XBX/MgO interface (s-MTJ) and double CoFeB-MgO interface (d-MTJ) structures with various boron compositions X. High TMR ratio over 100% was observed in the s-MTJ with X=35 at.% after annealing at 360 °C-400 °C, whereas the s-MTJ with X=30 at.% showed the degradation of TMR ratio with the increase of Ta above 360 °C, resulting from the decrease of perpendicular anisotropy. The d-MTJ with X=25 at.% maintained high TMR ratio up to Ta = 400°C owing to its higher perpendicular anisotropy compared with the s-MTJ. The difference of perpendicular anisotropy between the s-MTJ and the d-MTJ can be attributed to higher interfacial anisotropy together with lower saturation magnetization of the d-MTJs. The lower saturation magnetization is attributable to two MgO layers that suppress boron diffusion from CoFeB layers, which was verified by cross-sectional line analysis using electron energy-loss spectroscopy.

KW - CoFeB-MgO

KW - magnetic tunnel junction

KW - STT-MRAM

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DO - 10.1109/TMAG.2016.2518203

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SN - 0018-9464

VL - 52

JO - IEEE Transactions on Magnetics

JF - IEEE Transactions on Magnetics

IS - 7

M1 - 7383297

ER -

Improvement of Thermal Tolerance of CoFeB-MgO Perpendicular-Anisotropy Magnetic Tunnel Junctions by Controlling Boron Composition

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Keywords

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