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http://dx.doi.org/10.4283/JKMS.2007.17.4.162

Microstructural and Magnetic Properties of CoFeB/MgO/CoFeB Based Magnetic Tunnel Junction Depending on Capping Layer Materials  

Chung, Ha-Chang (Division of Materials Science and Engineering, Korea University)
Lee, Seong-Rae (Division of Materials Science and Engineering, Korea University)
Publication Information
Journal of the Korean Magnetics Society / v.17, no.4, 2007 , pp. 162-165 More about this Journal
Abstract
We investigated the effects of the capping layer materials on the crystallization of the amorphous top-CoFeB (t-CoFeB) electrode and the magnetoresistance properties of the magnetic tunnel junctions (MTJs). When the hcp(002)-textured Ru capping layer was used, the amorphous t-CoFeB was crystallized to bcc-CoFe(110). The CoFe(110)/Ru(002) texture relation can be minimized the lattice mismatch down to 5.6%. However, when the fine polycrystalline but almost amorphous TiAl or amorphous ZrAl were used, the amorphous t-CoFeB was crystallized to bcc-CoFe(002). When the amorphous capping materials were used, the evolution of the t-CoFeB texture was affected mainly by the MgO(001) texture. Consequently, the M ratios of the annealed MTJ capped with the ZrAl and TiAl (72.7 and 71.8%) are relatively higher than that of the MTJ with Ru capping layer (46.7%). In conclusions, the texture evolution of the amorphous t-CoFeB during the post deposition annealing could be controlled by the crystallinity of the adjacent capping layer and in turn, it affects the TMR ratio of MTJs.
Keywords
magnetic tunneling junction; tunneling magnetoresistance; capping; MgO; CoFeB;
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