Investigating the complex mechanism of B migration in a magnetic-tunnel-junction trilayer structure—a combined study using XPS and TOF-SIMS
| Autor: | Sze Ter Lim, Rong Ji, Chen Chen Wang, Franck Ernult, J. F. Ying, Michael N Tran |
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| Rok vydání: | 2015 |
| Předmět: |
010302 applied physics
Recording head Materials science Acoustics and Ultrasonics business.industry Annealing (metallurgy) Crystal orientation Nanotechnology 02 engineering and technology Chemical interaction 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Surfaces Coatings and Films Electronic Optical and Magnetic Materials Out of plane Tunnel magnetoresistance Stack (abstract data type) X-ray photoelectron spectroscopy 0103 physical sciences Optoelectronics 0210 nano-technology business |
| Zdroj: | Journal of Physics D: Applied Physics. 49:065004 |
| ISSN: | 1361-6463 0022-3727 |
| DOI: | 10.1088/0022-3727/49/6/065004 |
| Popis: | The magnetic-tunnel-junction (MTJ) structure is the core of many important devices, such as magnetic recording head and STT-RAM. CoFeB/MgO/CoFeB tri-layer thin-film stack is a widely researched MTJ structure. In this tri-layer, the functional property of the MTJ, i.e. its TMR ratio, is critically dependent on the crystal orientation of the CoFe grains. In order for the desired (1 0 0) out of plane texture to develop in the CoFeB layers, B needs to be engineered to be expelled out of these CoFeB layers, and diffuse or migrate into the adjacent layers. Ta is usually used as a seed layer adjacent to the MTJ structure. In this work, we investigated the important B-migration mechanisms within this MTJ structure through a combined XPS/TOF-SIMS study. Specifically, we tried to elucidate the possible physical/chemical interactions between the B and Ta that could happen with different film stack designs. Previous works have shown that there might be two possible B-migration mechanisms. One mechanism is direct B diffusion into the adjacent Ta layer during annealing. The other B-migration mechanism is through the formation of TaBOx species, in which B could be carried out by the Ta diffusion. In particular, through studying a series of film stacks, we discussed the circumstances under which one of these B-migration mechanisms becomes dominant. Furthermore, we discussed how these B-migration mechanisms facilitated the B expulsion in a common MTJ structure. |
| Databáze: | OpenAIRE |
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