利用金属掩模法制备钉扎型磁性隧道结

Fabrication of pinned magnetic tunnel junctions using a contact shadow mask method

利用金属掩模法和Ir2 2 Mn78合金反铁磁钉扎层 ,制备了四种钉扎型的Py Al2 O3 Py ,Py Al2 O3 Co ,Co Al2 O3 Py和Co Al2 O3 Co磁性隧道结 ,坡莫合金的成分为Py =Ni79Fe2 1 .例如 :利用狭缝宽度为 1 0 0 μm的金属掩模 ,直接制备出室温隧穿磁电阻比值为 1 7 2 %的磁性隧道结Co Al2 O3 Co,其结电阻为 76Ω ,结电阻和结面积的积矢为 76× 1 0 4 Ωμm2 ,自由层的偏转场为 1 1 1 4A m ,并且在外加磁场 0— 1 1 1 4A·m- 1 之间时室温磁电阻比值从零跳跃增加到 1 7 2 % ,磁场灵敏度达到 0 1 % (1 0 3A·m- 1 ) .钉扎型Co Al2 O3 Py的隧穿磁电阻实验曲线具有较好的方形度 .结果表明 。

Four types of pinned magnetic tunnel junctions (MTJs) with three key layer structures of Py/Al 2O 3/Py,Py/Al 2O 3/Co, Co/Al 2O 3/Py, Co/Al 2O 3/Co were fabricated using a contact shadow mask method and an antiferromagnetically pinned layer of Ir 22 Mn 78 . The slit width of the shadow mask is 100?μm, and the composition of permalloy is Py=Ni 79 Fe 21 .For example, the MTJs of Co/Al 2O 3/Co with a tunneling magnetoresistance (TMR) ratio of 17 2%, the junction resistance of 76?Ω, the resistance area product RS of 760?kΩμm 2, and the free layer reversal field of 1114?A·m -1 defined as the field where the TMR rises to 50% of the total jump were achieved at the as deposited state at room temperature. Furthermore, when the magnetic field increases from 0 to 1114?A·m -1 the TMR ratio jumps from 0 to 17 2% with one step, which shows that the magnetic field sensitivity of the junction reached at 0 1%/(10 3A·m -1 ). While, the TMR vs external filed H curves for the pinned MTJs of Co/Al 2O 3/Py show a good rectangular shape with a small free layer reversal filed of 1114?A·m -1 . Our experimental results show that such MTJs can be used to fabricate the magnetic field sensitive sensors or prototype demonstration devices of magnetoresistive random access memory.