Patent ID: 6927075

Claim:
A method for forming a magnetic tunneling junction (MTJ) memory cell having a flux-concentrating keeper structure on an upper conductor comprising: providing a substrate; forming on the substrate a planarized linear lower conductor layer having a width W 1 ; forming on said lower conductor layer a patterned, MTJ stack, said stack being centrally aligned and co-linear with said lower conductor layer and said stack having width W 2 which is less than width W 1 ; forming an insulating layer contiguous with and laterally disposed to each side of said MTJ stack, an upper surface of said insulating and an upper surface of said MTJ stack forming a common plane; forming an upper linear conductor on said plane, said conductor contacting said MTJ structure, said conductor being transverse to said MTJ structure, said conductor having a keeper structure and said conductor being formed by a method comprising; forming a conducting layer on said plane; forming a first soft magnetic layer on said conducting layer; forming a capping layer on said soft magnetic layer; patterning said layers to form a linear structure with a planar horizontal upper surface and planar parallel vertical surfaces, the width of said structure, W 3 , being substantially equal to W 2 , said structure being transverse to said MTJ stack and an upper surface of said MTJ stack being thereby exposed laterally on either side of said structure; removing, using a first etching process aligned by said vertical surfaces, an upper portion of said MTJ stack laterally disposed to either side of said linear structure; forming a second, continuous soft magnetic layer on exposed surfaces of said MTJ stack and on horizontal and vertical surfaces of said linear structure, said layer having an outer surface including vertical surface portions laterally disposed to either side of said linear structure and substantially parallel to said vertical sides; removing, using a second, etching process aligned by said vertical outer surface portions of said second soft magnetic layer, all horizontal portions of said second soft magnetic layer, leaving, thereby, only vertical portions contacting vertical sides of said linear conductor and exposing, thereby, an upper horizontal surface of said linear structure and an upper surface of said MTJ structure.