Hybrid method of patterning MTJ stack
OwnerYimin Guoinventor
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Abstract
This invention comprises a method to make small MTJ element using hybrid etching and oxygen plasma immersion ion implantation. The method has no removal of the magnetic free layer (or memory layer) and hence prevents any possible physical damage near the free layer edges. After photolithography patterning, alternative Ta, Ru, Ta etchings are performed before it stops on an MgO intermediate layer above the free layer. Then an oxygen plasma immersion ion implantation is performed to completely oxidize the exposed portion of the free layer, leaving the hard mask covered portion unchanged which define the lateral width of the MTJ element.
Claims21
A method of manufacturing a magnetic tunnel junction device comprising:
- an MTJ stack is formed on a substrate, the MTJ stack consists of a seed layer, a recording layer, a reference layer and a tunnel barrier layer disposed between the recording layer and the reference layer, an intermediate layer provided on a top surface of the MTJ stack, a protective cap layer provided on a top surface of the intermediate layer, a mask layer provided on a top surface of the cap layer and there is provided a method of patterning a magnetic tunnel junction which comprises:
- conducting a photolithographic process to form a patterned mask having an opening exposed area on the cap layer;
- etching the protective cap layer with stopping at the top surface of the intermediate layer;
- conducting an oxygen plasma immersion ion implantation to the depth position to the tunnel barrier layer from a surface of the intermediate layer exposed in the opening of the mask;
- refilling a dielectric layer;
- flattening the top surface by a CMP process;
- conducting a deposition and patterning of a top electrode;
- carrying out a thermal annealing with respect to the substrate to oxidize the plasma immersion ion implantation region so that a highly oxidized layer having a greatly increased resistance is formed and an oxidized recording layer having a highly increased resistance and zero or near zero magnetization moment is formed in the mask opening area;
- and forming a dielectric region outside of the mask opening area on the substrate and a functional magnetoresistive element underneath the mask covering area on the substrate.
Dependencies are inferred from the claim text.