Nano-analysis of Ta/FeCoB/MgO tunnel magneto resistance structures
Nano-analysis of Ta/FeCoB/MgO tunnel magneto resistance structures
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DOI：
10.1016/j.actamat.2016.06.045
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发表时间：
2016-09-01
期刊：
影响因子：
9.4
通讯作者：
Schmitz, G.
中科院分区：
文献类型：
--
作者：
Bouchikhaoui, H.;Stender, P.;Schmitz, G.
为了更好地理解Ta/FeCoB/MgO层状结构对FeCoB/MgO/FeCoB磁性隧道结的有利影响，采用原子探针层析技术研究了Ta/FeCoB/MgO层状结构中B在非晶FeCoB结晶过程中的分配和偏析。硼最初均匀地溶解在无定形的FeCo层中，在结晶时被FeCo晶粒排斥，并首先在Ta层的界面处偏析，在那里它阻止了结晶FeCo的成核。只是稍后，它才被Ta层完全吸收。在所研究的薄膜结构中，即使经过长时间的热处理，B也不会在MgO势垒处偏析或溶解。重要的动力学参数由详细的等时退火序列导出。它们允许对观察到的过程进行定量建模。对B的高亲和力和低扩散率的结合使Ta成为实现最佳性能的独特封盖材料。(C) 2016材料学报Elsevier Ltd.出版。版权所有。
The partitioning and segregation of B during the crystallization of amorphous FeCoB in Ta/FeCoB/MgO layered structures is investigated by atom probe tomography to obtain a better understanding of the beneficial impact of Ta capping layers on FeCoB/MgO/FeCoB magnetic tunneling junctions. Boron, initially uniformly dissolved in the amorphous FeCoB layer, is rejected from FeCo grains on crystallization and first segregates at the interface to the Ta layer where it prevents nucleation of crystalline FeCo. Only later, it is fully absorbed by the Ta layer. In the studied thin film structures, B neither segregates at nor dissolves into the MgO barrier even after prolonged heat treatment. Important kinetic parameters are derived from detailed isochronal annealing series. They allow the quantitative modelling of the observed process. The combination of high affinity to B but low diffusivity makes Ta the unique capping material to achieve an optimum performance. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.