TY - JOUR
T1 - Impact of Tungsten Sputtering Condition on Magnetic and Transport Properties of Double-MgO Magnetic Tunneling Junction with CoFeB/W/CoFeB Free Layer
AU - Honjo, H.
AU - Ikeda, S.
AU - Sato, Hideo
AU - Nishioka, K.
AU - Watanabe, T.
AU - Miura, S.
AU - Nasuno, T.
AU - Noguchi, Y.
AU - Yasuhira, M.
AU - Tanigawa, T.
AU - Koike, H.
AU - Inoue, H.
AU - Muraguchi, Masakazu
AU - Niwa, Masaaki
AU - Ohno, H.
AU - Endoh, T.
N1 - Funding Information:
ACKNOWLEDGMENT This work was supported in part by the Center for Innovative Integrated Electronic Systems Industrial Affiliation on STT MRAM program and in part by the Japan Science and Technology Agency ACCEL, Japan, under Grant JPMJAC1301.
Publisher Copyright:
© 1965-2012 IEEE.
PY - 2017/11
Y1 - 2017/11
N2 - We investigated an effect of sputtering gas species (Ar, Kr, and Xe) for deposition of a W insertion layer in the CoFeB/W/CoFeB free layer on magnetic properties of the free layer and tunnel magnetoresistance (TMR) ratio of magnetic tunnel junctions (MTJs) stacks using the free layer annealed at 400 °C for 1 h. As the W insertion layer thickness tW increased, we found the degradation of perpendicular anisotropy and larger reduction of saturation magnetic moment per unit area mS in the free layer using Ar compared to those using Kr and Xe. We also found a smaller TMR ratio for the MTJ stack using Ar compared to those using Kr and Xe. Energy-dispersive X-ray spectrometry line analysis revealed more significant interdiffusion between W and CoFeB layers in the free layer using Ar than those using Kr and Xe, that could result in the smaller m and perpendicular anisotropy in the free layer and smaller TMR ratio for the MTJ stack using Ar than those using Kr and Xe. We also investigated concentration of Ar, Kr, and Xe in W layers deposited using Ar, Kr, and Xe, respectively, by high-resolution Rutherford backscattering spectrometry, revealing that 0.2 at% Ar was detected in the W layer using Ar, while Kr and Xe were not detected in W layers using Kr and Xe. Such a difference in concentration of inert gas atoms in the W layer could be one possible reason for the difference about degree of interdiffusion between W and CoFeB layers.
AB - We investigated an effect of sputtering gas species (Ar, Kr, and Xe) for deposition of a W insertion layer in the CoFeB/W/CoFeB free layer on magnetic properties of the free layer and tunnel magnetoresistance (TMR) ratio of magnetic tunnel junctions (MTJs) stacks using the free layer annealed at 400 °C for 1 h. As the W insertion layer thickness tW increased, we found the degradation of perpendicular anisotropy and larger reduction of saturation magnetic moment per unit area mS in the free layer using Ar compared to those using Kr and Xe. We also found a smaller TMR ratio for the MTJ stack using Ar compared to those using Kr and Xe. Energy-dispersive X-ray spectrometry line analysis revealed more significant interdiffusion between W and CoFeB layers in the free layer using Ar than those using Kr and Xe, that could result in the smaller m and perpendicular anisotropy in the free layer and smaller TMR ratio for the MTJ stack using Ar than those using Kr and Xe. We also investigated concentration of Ar, Kr, and Xe in W layers deposited using Ar, Kr, and Xe, respectively, by high-resolution Rutherford backscattering spectrometry, revealing that 0.2 at% Ar was detected in the W layer using Ar, while Kr and Xe were not detected in W layers using Kr and Xe. Such a difference in concentration of inert gas atoms in the W layer could be one possible reason for the difference about degree of interdiffusion between W and CoFeB layers.
KW - CoFeB-MgO
KW - double interfaces structure
KW - interfacial anisotropy
KW - magnetic tunnel junction (MTJ)
KW - perpendicular anisotropy
KW - spin-transfer-torque magnetoresistive random access memory (STT-MRAM)
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U2 - 10.1109/TMAG.2017.2701838
DO - 10.1109/TMAG.2017.2701838
M3 - Article
AN - SCOPUS:85032948342
SN - 0018-9464
VL - 53
JO - IEEE Transactions on Magnetics
JF - IEEE Transactions on Magnetics
IS - 11
M1 - 7920343
ER -