Perpendicular magnetic fixed layer with high anisotropy
The present invention is directed to an MTJ memory element, which includes a magnetic free layer structure having a variable magnetization direction perpendicular to a layer plane thereof; a tunnel junction layer formed adjacent to the magnetic free layer structure; a magnetic reference layer structure formed adjacent to the tunnel junction layer and having a first invariable magnetization direction perpendicular to a layer plane thereof; an anti-ferromagnetic coupling layer formed adjacent to the magnetic reference layer structure; and a magnetic fixed layer structure formed adjacent to the anti-ferromagnetic coupling layer and having a second invariable magnetization direction that is perpendicular to a layer plane thereof and is opposite to the first invariable magnetization direction. The magnetic fixed layer structure includes multiple stacks of a trilayer unit structure, which includes three layers of different materials with at least one of the three layers of different materials being magnetic.
1. A magnetic structure comprising:
a seed layer; and
a magnetic fixed layer structure formed adjacent to said seed layer and having a first invariable magnetization direction substantially perpendicular to a layer plane thereof,
wherein said magnetic fixed layer structure includes a trilayer unit structure and at least one repeat thereof in contiguous contact, said trilayer unit structure including three layers of different materials in contiguous contact with at least one of said three layers of different materials being magnetic.
2. The magnetic structure of claim 1 , wherein said trilayer unit structure includes a layer of cobalt, a layer of chromium, and a layer of nickel.
3. The magnetic structure of claim 1 , wherein said trilayer unit structure includes a layer of Co, a layer of a transition metal, and a layer of Ni, said transition metal being selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, and tungsten.
4. The magnetic structure of claim 1 further comprising:
an anti-ferromagnetic coupling layer formed adjacent to said magnetic fixed layer structure opposite said seed layer; and
a magnetic reference layer formed adjacent to said anti-ferromagnetic coupling layer opposite said magnetic fixed layer structure, said magnetic reference layer having a second invariable magnetization direction that is substantially perpendicular to a layer plane thereof and is substantially opposite to said first invariable magnetization direction.
5. A magnetic tunnel junction (MTJ) memory element comprising:
a magnetic free layer structure including one or more magnetic free layers that have a variable magnetization direction substantially perpendicular to layer planes thereof;
an insulating tunnel junction layer formed adjacent to said magnetic free layer structure;
a magnetic reference layer structure formed adjacent to said insulating tunnel junction layer opposite said magnetic free layer structure, said magnetic reference layer structure including one or more magnetic reference layers that have a first invariable magnetization direction substantially perpendicular to layer planes thereof;
an anti-ferromagnetic coupling layer formed adjacent to said magnetic reference layer structure opposite said insulating tunnel junction layer; and
a magnetic fixed layer structure formed adjacent to said anti-ferromagnetic coupling layer opposite said magnetic reference layer structure, said magnetic fixed layer structure having a second invariable magnetization direction that is substantially perpendicular to a layer plane thereof and is substantially opposite to said first invariable magnetization direction,
wherein said magnetic fixed layer structure includes a trilayer unit structure and at least one repeat thereof in contiguous contact, said trilayer unit structure including three layers of different materials in contiguous contact with at least one of said three layers of different materials being magnetic.
6. The MTJ memory element of claim 5 , wherein said trilayer unit structure includes a layer of cobalt, a layer of chromium, and a layer of nickel.
7. The MTJ memory element of claim 5 , wherein said trilayer unit structure includes a layer of Co, a layer of a transition metal, and a layer of Ni, said transition metal being selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, and tungsten.
8. The MTJ memory element of claim 5 , wherein said magnetic reference layer structure includes a first magnetic reference layer formed adjacent to said insulating tunnel junction layer and a second magnetic reference layer separated from said first magnetic reference layer by a perpendicular enhancement layer (PEL).
9. The MTJ memory element of claim 8 , wherein said PEL is made of molybdenum.
10. The MTJ memory element of claim 8 , wherein said second magnetic reference layer has a multilayer structure comprising layers of a first material interleaved with layers of a second material, at least one of said first and second materials being magnetic.
11. The MTJ memory element of claim 10 , wherein said first and second materials are cobalt and platinum, respectively.
12. The MTJ memory element of claim 8 , wherein said first magnetic reference layer comprises cobalt, iron, and boron.
13. The MTJ memory element of claim 5 , wherein said magnetic free layer structure includes a first magnetic free layer formed adjacent to said insulating tunnel junction layer and a second magnetic free layer separated from said first magnetic free layer by a perpendicular enhancement layer (PEL).
14. The MTJ memory element of claim 13 , wherein said PEL is made of molybdenum.
15. The MTJ memory element of claim 13 , wherein each of said first and second magnetic free layers comprises cobalt, iron, and boron.
16. The magnetic structure of claim 4 , wherein said anti-ferromagnetic coupling layer comprises iridium.
17. The MTJ memory element of claim 5 , wherein said anti-ferromagnetic coupling layer comprises iridium.