Magnetic tunnel junctions with a tunnel barrier formed by N[sub 2]O plasma

Shim, Heejae; Park, J. M.; Kim, K. P.; Cho, B. K.; Jin-Tae Kim; Park, Y.
December 2003
Applied Physics Letters;12/1/2003, Vol. 83 Issue 22, p4583
Academic Journal
We investigated a magnetic tunnel junction (MTJ) with a tunnel barrier formed by N[sub 2]O plasma. Compared with a MTJ with a tunnel barrier formed by conventional O[sub 2] plasma, the MTJ fabricated with N[sub 2]O plasma shows much lower specific junction resistance and a comparably high tunneling magnetoresistance ratio. In particular, it was found that N[sub 2]O plasma oxidation is quite important in the junction with a thin tunnel barrier, for which O[sub 2] plasma cannot be used. From x-ray photoelectron spectroscopy, we observed that N[sub 2]O plasma oxidation leads to the slight nitridation of the Al[sub 2]O[sub 3] layer and significantly reduces the oxidation of the bottom electrode, especially for a thin tunnel barrier. Thus, we conclude that the use of N[sub 2]O plasma in forming the tunnel barrier is effective for achieving a low junction resistance and for minimizing the oxidation of the bottom electrode during plasma oxidation in MTJs. © 2003 American Institute of Physics.


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