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Annealing Stability Study of Perpendicular Magnetic Tunnel Junctions Co sub(20)Fe sub(60)B sub(20)/MgO\Co sub(20)Fe sub(60)B sub(20)

Published

Author(s)

Andrew P. Chen, M Zhu, T, Dyer, J. Piccirillo, Robert D. Shull

Abstract

A Full Co sub(20)Fe sub (60) B sub (20)\MgO\Co sub (20) Fe sub (60) B sub (20) perpendicular magnetic tunnel junction (pMTJ) and a different partial stacks were made and annealed at different temperatures. The tunneling magnetoresistance ratio (TMR) and MgO barrier resistance-area product (RA) were measured and analyzed as a function of annealing temperature. The TMR of pMTJs dramatically declines with increasing annealing temperatures from 320 degrees C to 400 degrees C while the RA increases with temperature from 375 degrees C to 450 degrees C. The pMTJs and partial stacks were also measured in a vibrating sample magnetometer (VSM). We found that the (Co\Pt) multilayers are very stable and maintain a magnetization direction perpendicular to the film plane up to 450 degrees C. However, the magnetization direction of the CoFeB above and below the MgO barrier rotates from perpendicular to in-plane with increasing annealing temperature. Furthermore, the CoFeB layer influences the adjacent (Co\Pt) layers to rotate at the same time. The pMTJs' elemental depth profiles in the as deposited and annealed states were determined by Secondary Ion Mass Spectrometry (SIMS). We found that Boron and Tantalum migrate towards the top of the stack. The other elements (Platinum, Cobalt, Ruthenium, and Magnesium) are very stable and do not interdiffuse during annealing to to 450 degrees C.
Citation
Journal of Physics D-Applied Physics
Volume
50

Keywords

tunnel junction, annealing stability

Citation

Chen, A. , Zhu, M. , Piccirillo, J. and Shull, R. (2016), Annealing Stability Study of Perpendicular Magnetic Tunnel Junctions Co sub(20)Fe sub(60)B sub(20)/MgO\Co sub(20)Fe sub(60)B sub(20), Journal of Physics D-Applied Physics (Accessed April 16, 2024)
Created December 2, 2016, Updated February 19, 2017