Microfabrication of magnetic tunnel junctions using Al as bottom conduction electrode

Magnetic tunnel junctions (MTJs) with the layer structures of Ta (5 nm)/Al(20 nm)/Ni₇₉Fe₂₁(5 nm)/Ir₂₂Mn₇₈(10 nm)/Co₇₅Fe₂₅(4 nm)/Al(0.8 nm)-oxide/Co₇₅Fe₂₅(4 nm)/Ni₇₉Fe₂₁ (20 nm)/Ta(5 nm) were fabricated using Al as a conduction layer/electrode and lithographic methods. A high magneto-resistance ratio of 16% and 45% and resistance-area product RS of 11.8 kΩμm² and 11.6 kΩμm² in the as-deposited state and after annealing were attained at room temperature. After annealing, the coercivity of the free layer is about 23.4 Oe. Such MTJs can be used to fabricate the cell of magnetoresistive random access memory and other magnetic field sensors after further optimization.