Patent ID: 6974708

Claim:
A method of forming a magnetic tunneling junction (MTJ) MRAM device comprising: providing a substrate; a formation process of forming, in a high vacuum deposition system, a bottom conductor layer on said substrate, said formation process further comprising: forming a conducting lead layer on said substrate; forming a Ta capping layer on said metal layer; and sputter-etching said Ta capping layer; forming, in the same high vacuum deposition system a lower pinned electrode, said formation further comprising: forming an NiCr seed layer on said sputter-etched Ta layer; forming, an AFM pinning layer on said seed layer; forming a synthetic antiferromagnetic pinned (SyAP) layer on said pinning layer, said formation comprising a lower ferromagnetic layer formed on said pinning layer, a coupling layer formed on said lower ferromagnetic layer and an upper ferromagnetic layer formed on said coupling layer; forming, in an oxidation chamber an oxygen surfactant layer on said upper ferromagnetic layer; forming, a tunneling barrier layer on said oxygen surfactant layer, said formation further comprising: forming, in said high vacuum deposition system, a layer of Al on said oxygen surfactant layer, said deposition first causing the adsorption of substantially all oxygen from said surfactant layer into said Al layer to form an amorphous layer of stoichiometric Al 2 O 3 and, upon the depletion of all said oxygen in said surfactant layer, the remainder of said deposition forming a flat and smooth Al layer of small and uniform grain size; then oxidizing said flat and smooth Al layer in a plasma oxidation chamber by a process of radical oxidation, said process forming from said flat and smooth Al layer an oxidized layer of stoichiometric Al 2 O 3 , said oxidized layer extending to said amorphous layer of stoichiometric Al 2 O 3 formed during said Al deposition, to form, thereby, a tunneling barrier layer of substantially homogeneous Al 2 O 3 stoichiometry; and forming, in said high vacuum system a free layer on said tunneling barrier layer; forming, in said high vacuum system an upper capping layer on said free layer; annealing said MTJ MRAM device to magnetize said pinned layer, said annealing process further enhancing the Al 2 O 3 stoichiometry of the tunneling barrier layer.