Tunnel junctions with AlN barriers and FeTaN electrodes

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Abstract
Tunnel junctions with AlN (AlNxOy) barriers and CoFe and FeTaN electrodes were studied. The AlN barrier was formed by nitridizing a 10 Å thick Al layer using radio frequency N 2 plasma. The nitrogen and oxygen content in the barriers was determined by Rutherford backscattering spectroscopy (RBS) on specially prepared barriers deposited on DLC coated substrates. RBS results indicate less than 10% O 2 incorporation in the barrier. Top-pinned junctions formed by nitridizing a 10 Å thick Al layer (CoFe electrodes) show resistance×area products from 73 Ω μ m 2 to 8.5 k Ω μ m 2 for increasing nitridation times from 30 to 200 s, with corresponding tunnelingmagnetoresistance(TMR) values from 13% to 33%. Bottom-pinned junctions with FeTaN electrodes were also fabricated. Maximum TMR signal is 17% after anneal at 225 ° C for 30 min. In both cases (CoFe or FeTaN electrodes),TMR degrades for anneals above 250 ° C .