Microstructure and chemical analysis of the magnetic tunneling junctions

摘要

To investigate the thermal breakdown mechanism of low resistance magnetic tunneling junctions (MTJ) with 100 ～ 1000 Ω μm~2. Ta/NiFe/Cu/NiFe/IrMn/CoFe/Al(6.6A and 7.7A)-oxide/CoFe/NiFe/Ta multi-layer was fabricated and heat treated at temperatures ranging from 200 °C to 500 °C under vacuum. Both Al(6.6A) and Al(7.7A)-oxide junctions showed the expected annealing behavior, exhibiting optimal MR ratio at 200 ～ 300 °C after which MR ratio dropped rapidly. However, in spite of only 1A difference in Al-deposited thickness, MR behavior for the Al(6.6A)-oxide junction was lost at a much lower temperature compared to the Al(7.7A)-oxide junction.