Non-volatile memory cell with lateral pinning
View Patent ↗An apparatus and associated method for a non-volatile memory cell, such as an STRAM cell. In accordance with various embodiments, a magnetic free layer is laterally separated from an antiferromagnetic layer (AFM) by a non-magnetic spacer layer and medially separated from a synthetic antiferromagnetic layer (SAF) by a magnetic tunneling junction. The AFM pins the magnetization of the SAF through contact with a pinning region of the SAF that laterally extends beyond the magnetic tunneling junction.
1. A method comprising:
providing a magnetic free layer laterally separated from an antiferromagnetic layer (AFM) by a non-magnetic spacer layer and medially separated from a synthetic antiferromagnetic layer (SAF) by a magnetic tunneling junction;
pinning the magnetization of the SAF with the AFM through contact with a pinning region of the SAF that laterally extends beyond the magnetic tunneling junction; and
annealing the magnetic free layer, magnetic tunneling junction, and SAF in the presence of in-plane magnetic field to increase tunnel magnetoresistance between the magnetic free layer and SAF.
2. The method of claim 1 , wherein the annealing step concurrently provides an elevated temperature for the magnetic free layer, magnetic tunneling junction, and SAF to increase the tunnel magnetoresistance of the free layer, tunnel junction, and SAF.
3. The method of claim 2 , wherein the pinning region inhibits magnetically volatile AFM atoms from diffusing to the SAF during annealing.
4. The method of claim 1 , wherein the AFM is deposited to be physically and magnetically separated from the free layer and a top electrode by the spacer layer.
5. The method of claim 1 , wherein the AFM pins the SAF with an exchange bias field.
6. The method of claim 1 , wherein the SAF is deposited with a first width, the tunnel junction has a second width, and the free layer has a third width, the pinning region defined by the difference between the first and second widths.
7. The method of claim 1 , wherein the SAF has a width that is at least twice as long as the width of the free layer.
8. The method of claim 1 , wherein the pinning region is formed by removing lateral portions of the tunnel junction.