Effect of Buffer Layer Texture on the Crystallization of CoFeB and on the Tunnel Magnetoresistance in MgO Based Magnetic Tunnel Junctions
Effect of Buffer Layer Texture on the Crystallization of CoFeB and on the Tunnel Magnetoresistance in MgO Based Magnetic Tunnel Junctions
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DOI：
10.1109/tmag.2009.2025382
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发表时间：
2009-09
影响因子：
2.1
通讯作者：
J. Cao;J. Kanak;T. Stobiecki;P. Wiśniowski;P. Freitas
中科院分区：
文献类型：
--
作者：
J. Cao;J. Kanak;T. Stobiecki;P. Wiśniowski;P. Freitas
针对MgO MTJ测试两种不同的缓冲层（Ta/Ru/Ta和厚Ta）。研究了缓冲层织构对CoFeB底电极和顶电极晶化以及隧道磁电阻效应的影响。X射线衍射结果表明，退火后，MgO上方的CoFeB层具有良好的（200）织构，并且它不依赖于缓冲层，因为MgO（100）阻挡层为CoFeB（200）取向提供了良好的模板，而底部CoFeB层的结晶依赖于缓冲层织构。与Ta/Ru/Ta缓冲层中的Ta（110）不同，厚Ta缓冲层具有β-（200）织构，这诱导MnPt层中的（001）取向晶粒。由于MnPt和FeCo之间的外延关系为MnPt（001）[100]//FeCo（200）[110]，MnPt（001）取向的晶粒导致底部CoFeB层以（200）取向结晶。结果表明，在具有厚Ta缓冲层的EB-MTJ中实现了高达290%的较高TMR比。
Two different buffer layers (Ta/Ru/Ta and thick Ta) were tested for MgO MTJs. The influence of buffer layer texture on the crystallization of CoFeB bottom and top electrodes and on the tunnel magnetoresistance effect was investigated. X-ray results suggest that, after anneal, the CoFeB layer above MgO is well (200) textured and it does not depend on the buffer layer since MgO (100) barrier supplies a good template for CoFeB (200) orientation, while the crystallization of bottom CoFeB layer relies on the buffer layer texture. Different from Ta (110) found in Ta/Ru/Ta buffer layer, a thick Ta buffer layer has beta-(200) texture, which induces (001) oriented grains in MnPt layer. Because of the epitaxy relationship between MnPt and FeCo with MnPt(001)[100]//FeCo(200)[110], MnPt (001) oriented grains lead to the crystallization of bottom CoFeB layer with (200) orientation. As a result, higher TMR ratio up to 290% was achieved in the EB-MTJs with thick Ta buffer layer.