Patent ID: 7217577

Claim:
A method of forming a magnetic tunneling junction (MTJ) MRAM device with smooth and flat layers in its lower pinned electrode and a smooth tunneling barrier layer of high breakdown voltage comprising: providing a substrate; forming, in a high vacuum sputter-deposition chamber, a bottom magnetic keeper and conductor layer on said substrate, said formation process further comprising: forming a first NiCr seed layer in said substrate; forming a soft magnetic keeper layer on said seed layer; forming a conducting lead layer on said keeper layer; forming a first Ta layer as a capping layer on said conducting lead layer; forming a Ru layer on said Ta capping layer; and completely removing said Ru layer by sputter-etching; and partially sputter-etching said Ta capping layer; forming, in the same high vacuum sputter-deposition chamber a lower pinned electrode, said formation further comprising: forming a second NiCr seed layer on said sputter-etched Ta capping layer; forming, an AFM pinning layer on said seed layer; forming a synthetic antiferromagnetic pinned (SyAP) layer on said pinning layer; forming a tunneling barrier layer on said lower electrode, said formation further comprising: forming, in said high vacuum sputter-deposition chamber a layer of Al on said SyAP layer; oxidizing, in an oxidation chamber, said Al layer by an in-situ process of radical oxidation, said oxidized layer of Al to form a tunneling barrier layer on said pinned layer, said tunneling barrier layer being smooth and having a high breakdown voltage; and forming, in said high vacuum sputter-deposition chamber a free layer on said tunneling barrier layer; then forming, in said high vacuum sputter-deposition chamber an upper capping layer on said free layer.