Patent ID: 7456029

Claim:
A low cost process to manufacture a flux concentrator, comprising: providing an MTJ stack, including a capping layer having a top surface, a bottom electrode, and a dielectric layer, having a top surface, that encapsulates said MTJ stack and extends above said capping layer; etching in said dielectric layer a trench, having vertical sidewalls, that is longer and wider than said capping layer and that extends downwards as far as said capping layer top surface; then just filling said trench with a conductive material, thereby forming a bit line that passes over said MTJ stack and that has a top surface coplanar with said dielectric top surface; then depositing an insulating layer on said coplanar surfaces; depositing on said insulating layer a ferromagnetic layer; depositing an antiferromagnetic layer on said ferromagnetic layer, thereby forming a concentrator for magnetic flux that results from the passage of current through said bit line; and annealing said ferromagnetic and antiferromagnetic layers in the presence of a magnetic field whose direction is parallel to that of said bit line thereby providing a domain stabilizing field for said ferromagnetic layer.