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Enhanced annealing stability and perpendicular magnetic anisotropy in perpendicular magnetic tunnel junctions using W layer
Abstract : The magnetic properties of the perpendicular storage electrode (buffer/MgO/FeCoB/Cap) were studied as a function of annealing temperature by replacing Ta with W and W/Ta cap layers with variable thicknesses. W in the cap boosts up the annealing stability and increases the effective perpendicular anisotropy by 30% compared to the Ta cap. Correspondingly, an increase in the FeCoB critical thickness characterizing the transition from perpendicular to in-plane anisotropy was observed. Thicker W layer in the W(t)/Ta 1 nm cap layer makes the storage electrode highly robust against annealing up to 570 °C. The stiffening of the overall stack resulting from the W insertion due to its very high melting temperature seems to be the key mechanism behind the extremely high thermal robustness. The Gilbert damping constant of FeCoB with the W/Ta cap was found to be lower when compared with the Ta cap and stable with annealing. The evolution of the magnetic properties of bottom pinned perpendicular magnetic tunnel junctions (p-MTJ) stack with the W2/Ta1 nm cap layer shows back-end-of-line compatibility with increasing tunnel magnetoresistance up to the annealing temperature of 425 °C. The pMTJ thermal budget is limited by the synthetic antiferromagnetic hard layer which is stable up to 425 °C annealing temperature while the storage layer is stable up to 455 °C.
Cited literature [22 references]
https://hal.archives-ouvertes.fr/hal-01629546
Contributor : Antoine Chavent Connect in order to contact the contributor
Submitted on : Tuesday, June 26, 2018 - 6:05:11 PM
Last modification on : Tuesday, May 11, 2021 - 11:36:05 AM
Long-term archiving on: : Wednesday, September 26, 2018 - 11:25:04 PM
Contributor : Antoine Chavent Connect in order to contact the contributor
Submitted on : Tuesday, June 26, 2018 - 6:05:11 PM
Last modification on : Tuesday, May 11, 2021 - 11:36:05 AM
Long-term archiving on: : Wednesday, September 26, 2018 - 11:25:04 PM
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Chatterjee_Enhanced_2017.pdf
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