Magnetic random access memory with nickel/transition metal multilayered seed structure
View Patent ↗The present invention is directed to a magnetic random access memory element that includes a multilayered seed structure formed by interleaving a first type sublayer and a second type sublayer to form one or more repeats of a unit bilayer structure and a first magnetic layer formed on top of the multilayered seed structure. The unit bilayer structure is made of the first and second type sublayers with at least one of the first and second type sublayers including therein one or more ferromagnetic elements. The multilayered seed structure may be amorphous or non-magnetic or both. The unit bilayer structure may be made of CoFeB and Ta sublayers.
1. 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 tantalum; 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 layer plane thereof.
2. The magnetic random access memory element according to claim 1 , wherein said multilayered seed structure is non-magnetic or superparamagnetic.
3. The magnetic random access memory element according to claim 1 , wherein said multilayered seed structure is amorphous.
4. The magnetic random access memory element according to claim 1 , wherein said multilayered seed structure is formed by interleaving multiple layers of nickel with multiple layers of tantalum.
5. The magnetic random access memory element according to claim 1 , wherein said first magnetic layer has a multilayer structure 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.
6. The magnetic random access memory element according to claim 5 , wherein said first type material is Co or CoFe.
7. The magnetic random access memory element according to claim 5 , wherein said second type material is Ni, Pd, Pt, or any combination thereof.
8. 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.
9. The magnetic random access memory element according to claim 8 , wherein said second magnetic layer includes at least two magnetic sublayers, one of said at least two magnetic sublayers being formed adjacent to said anti-ferromagnetic coupling layer and having a multilayer structure formed by interleaving layers of a third type material with layers of a fourth type material, at least one of said third and fourth type materials being magnetic.
10. The magnetic random access memory element according to claim 9 , wherein said third type material is Co or CoFe.
11. The magnetic random access memory element according to claim 9 , wherein said fourth type material is Ni, Pd, Pt, or any combination thereof.
12. The magnetic random access memory element according to claim 9 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 comprises cobalt and iron.
14. The magnetic random access memory element according to claim 12 , wherein said third magnetic layer comprises cobalt, iron, and boron.
15. The magnetic random access memory element according to claim 12 , wherein said third magnetic layer includes a first magnetic sublayer made of CoFeB and a second magnetic sublayer made of CoFeTa or CoFeHf.
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 a transition metal; 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 layer plane thereof,
wherein said transition metal is titanium, zirconium, hafnium, vanadium, niobium, or tungsten.
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 said transition metal.
18. The magnetic random access memory element according to claim 16 , wherein said first magnetic layer has a multilayer structure 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 16 , wherein said first type material is Co or CoFe.
20. The magnetic random access memory element according to claim 16 , wherein said second type material is Ni, Pd, Pt, or any combination thereof.