Dual Magnetic Tunnel Junction (DMTJ) Stack Design

A dual magnetic tunnel junction (DMTJ), comprising:

• (a) a first pinned ferromagnetic layer (PL1) on a substrate;
• (b) a first tunnel barrier layer (TB1) formed on PL1, and having a first resistance×area product (RA1);
• (c) a free layer (FL) that contacts a top surface of TB1 and having a magnetization aligned orthogonal to the substrate;
• (d) a second tunnel barrier layer (TB2) adjoining a top surface of the FL, and with a second resistance×area product (RA2) that is substantially greater than RA1;
• (e) a second pinned ferromagnetic layer (PL2) formed on TB2 wherein PL2 comprises:
• (1) a first sub-layer contacting a top surface of TB2, and with a body centered cubic (bcc) crystal structure wherein a magnetization is aligned orthogonal to the substrate, and antiparallel to a PL1 magnetization;
• and
• (2) an uppermost second sub-layer that has a face center cubic (fcc) (111) crystal texture to enhance perpendicular magnetic anisotropy (PMA) within PL2, and that is ferromagnetically coupled to the first sub-layer;
• and
• (f) a hard mask layer on a top surface of PL2.

A method of forming a dual magnetic tunnel junction (DMTJ), comprising:

• (a) depositing a first pinned ferromagnetic layer (PL1) on a substrate;
• (b) forming a first tunnel barrier layer (TB1) on PL1, and having a first resistance×area product (RA1);
• (c) depositing a free layer (FL) that contacts a top surface of TB1;
• (d) forming a second tunnel barrier layer (TB2) that adjoins a top surface of the FL, and with a second resistance×area product (RA2) that is substantially greater than RA1;
• (e) depositing a second pinned ferromagnetic layer (PL2) on TB2;
• (f) forming a metal oxide or metal oxynitride capping layer that contacts a top surface of PL2, and having a resistance×area product (RACAP) that is substantially less than RA2;
• and
• (g) performing an initialization process wherein a PL1 magnetization is aligned antiparallel to a PL2 magnetization, and a FL magnetization as well as both PL1 and PL2 magnetizations are aligned orthogonal to the substrate.