Multilayered seed structure for perpendicular MTJ memory element
View Patent ↗The present invention is directed to a magnetic random access memory element that includes a multilayered seed structure formed by interleaving multiple layers of a first transition metal with multiple layers of a second transition metal; and a first magnetic layer formed on top of the multilayered seed structure. The first magnetic layer has a multilayer structure formed by interleaving layers of the first transition metal with layers of a magnetic material and has a first fixed magnetization direction substantially perpendicular to a layer plane thereof. The first transition metal is platinum or palladium, while the second transition metal is selected from the group consisting of tantalum, titanium, zirconium, hafnium, vanadium, niobium, chromium, molybdenum, and tungsten.
1. A magnetic random access memory element comprising:
a multilayered seed structure formed by interleaving multiple layers of a first transition metal with multiple layers of a second transition metal; and
a first magnetic layer formed on top of said multilayered seed structure, said first magnetic layer having a multilayer structure formed by interleaving layers of said first transition metal with layers of a magnetic material and having a first fixed magnetization direction substantially perpendicular to a layer plane thereof,
wherein said first and second transition metals are non-magnetic.
2. The magnetic random access memory element according to claim 1 , wherein said first transition metal is platinum.
3. The magnetic random access memory element according to claim 1 , wherein said first transition metal is palladium.
4. The magnetic random access memory element according to claim 1 , wherein said second transition metal is tantalum.
5. The magnetic random access memory element according to claim 1 , wherein said second transition metal is titanium.
6. The magnetic random access memory element according to claim 1 , wherein said second transition metal is tungsten.
7. The magnetic random access memory element according to claim 1 , wherein said second transition metal is chromium.
8. The magnetic random access memory element according to claim 1 , wherein said second transition metal is selected from the group consisting of zirconium, hafnium, vanadium, niobium, and molybdenum.
9. The magnetic random access memory element according to claim 1 , wherein the magnetic material is Co or CoFe.
10. The magnetic random access memory element according to claim 1 further comprising:
an anti-ferromagnetic coupling layer formed on top of said first magnetic layer; and
a second magnetic layer formed on top of said anti-ferromagnetic coupling layer,
wherein said second magnetic layer has a second fixed magnetization direction that is substantially perpendicular to a layer plane thereof and is substantially opposite to said first fixed magnetization direction.
11. The magnetic random access memory element according to claim 10 , wherein said second magnetic layer includes at least two magnetic sublayers, one of said at least two magnetic sublayers being made of CoFeB.
12. The magnetic random access memory element according to claim 10 further comprising:
an insulating tunnel junction layer formed on top of said second magnetic layer; and
a third magnetic layer formed on top of said insulating tunnel junction layer,
wherein said third magnetic layer has a variable magnetization direction substantially perpendicular to a layer plane thereof.
13. The magnetic random access memory element according to claim 12 , wherein said third magnetic layer includes at least a magnetic sublayer made of CoFeTa, CoFeHf, or CoFeMo.
14. The magnetic random access memory element according to claim 12 , wherein said third magnetic layer includes at least a magnetic sublayer made of CoFeB.
15. The magnetic random access memory element according to claim 12 , wherein said third magnetic layer is made of CoFeB.
16. A magnetic random access memory element comprising:
a multilayered seed structure formed by interleaving one or more layers of nickel with one or more layers of molybdenum; and
a first magnetic layer formed on top of said multilayered seed structure, said first magnetic layer having a first fixed magnetization direction substantially perpendicular to a layer plane thereof.
17. The magnetic random access memory element according to claim 16 , wherein said multilayered seed structure is formed by interleaving multiple layers of nickel with multiple layers of molybdenum.
18. The magnetic random access memory element according to claim 16 , wherein said first magnetic layer is formed by interleaving layers of a first type material with layers of a second type material, at least one of said first and second type materials being magnetic.
19. The magnetic random access memory element according to claim 18 , wherein said first type material is Co or CoFe.
20. The magnetic random access memory element according to claim 18 , wherein said second type material is Ni, Pd, Pt, or any combination thereof.