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)/Ni/sub 79/Fe/sub 21/(5 nm)/Ir/sub 22/Mn/sub 78/(10 nm)/Co/sub 75/Fe/sub 25/(4 nm)/Al(0.8 nm)-oxide/Co/sub 75/Fe/sub 25/(4 nm)/Ni/sub 79/Fe/sub 21/ (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 k(omega)(mu)m/sup 2/ and 11.6 k(omega)(mu)m/sup 2/ 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.