Magnetic memory element with composite perpendicular enhancement layer

1. 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 including one or more magnetic reference layers that have a first fixed 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;

a magnetic fixed layer formed adjacent to said anti-ferromagnetic coupling layer opposite said magnetic reference layer structure, said magnetic fixed layer having a second fixed magnetization direction that is substantially perpendicular to a layer plane thereof and is substantially opposite to said first fixed magnetization direction; and

an iridium seed layer formed adjacent to said magnetic fixed layer opposite said anti-ferromagnetic coupling layer.

2. The MTJ memory element of claim 1 , 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, said first and second magnetic reference layers having said first fixed magnetization direction substantially perpendicular to layer planes thereof.

3. The MTJ memory element of claim 1 , 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, said first and second magnetic free layers having said variable magnetization direction substantially perpendicular to layer planes thereof.

4. 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 including 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 non-magnetic perpendicular enhancement layer, said first and second magnetic reference layers having a first fixed magnetization direction substantially perpendicular to layer planes thereof;

an anti-ferromagnetic coupling layer formed adjacent to said second magnetic reference layer opposite said non-magnetic perpendicular enhancement layer; and

a magnetic fixed layer formed adjacent to said anti-ferromagnetic coupling layer opposite said second magnetic reference layer, said magnetic fixed layer having a second fixed magnetization direction that is substantially perpendicular to a layer plane thereof and is substantially opposite to said first fixed magnetization direction,

wherein said non-magnetic perpendicular enhancement layer includes a first perpendicular enhancement sublayer formed adjacent to said first magnetic reference layer and a second perpendicular enhancement sublayer formed adjacent to said second magnetic reference layer.

5. The MTJ memory element of claim 4 , wherein said first magnetic reference layer is made of an alloy comprising cobalt, iron, and boron.

6. The MTJ memory element of claim 4 , wherein said first perpendicular enhancement sublayer is made of tungsten or molybdenum.

7. The MTJ memory element of claim 4 , wherein said second perpendicular enhancement sublayer is made of tantalum or hafnium.

8. The MTJ memory element of claim 4 , wherein said second perpendicular enhancement sublayer is made of zirconium or niobium.

9. The MTJ memory element of claim 4 , wherein said non-magnetic perpendicular enhancement layer further includes a third perpendicular enhancement sublayer formed between said first and second perpendicular enhancement sublayers.

10. The MTJ memory element of claim 9 , wherein said first and second perpendicular enhancement sublayers are made of molybdenum or tungsten, said third perpendicular enhancement sublayer is made of tantalum or hafnium.

11. 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 including one or more magnetic reference layers that have a first fixed 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;

a magnetic fixed layer formed adjacent to said anti-ferromagnetic coupling layer opposite said magnetic reference layer structure, said magnetic fixed layer having a second fixed magnetization direction that is substantially perpendicular to a layer plane thereof and is substantially opposite to said first fixed magnetization direction;

a first non-magnetic layer formed adjacent to said magnetic free layer structure opposite said insulating tunnel junction layer; and

a second non-magnetic layer formed adjacent to said first non-magnetic layer opposite said magnetic free layer structure.

12. The MTJ memory element of claim 11 , wherein said magnetic free layer structure includes a magnetic free layer made of an alloy comprising cobalt, iron, and boron.

13. The MTJ memory element of claim 11 , wherein said first non-magnetic layer is made of tungsten or molybdenum.

14. The MTJ memory element of claim 11 , wherein said second non-magnetic layer is made of tantalum or hafnium.

15. The MTJ memory element of claim 11 , wherein said second non-magnetic layer is made of zirconium or niobium.

16. A magnetic tunnel junction (MTJ) memory element comprising:

a magnetic free layer structure including a first magnetic free layer and a second magnetic free layer with a non-magnetic perpendicular enhancement layer interposed therebetween, said first and second magnetic free layers having a variable magnetization direction substantially perpendicular to layer planes thereof;

an insulating tunnel junction layer formed adjacent to said first magnetic free layer;

a magnetic reference layer structure including one or more magnetic reference layers that have a first fixed 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 formed adjacent to said anti-ferromagnetic coupling layer opposite said magnetic reference layer structure, said magnetic fixed layer having a second fixed magnetization direction that is substantially perpendicular to a layer plane thereof and is substantially opposite to said first fixed magnetization direction,

wherein said non-magnetic perpendicular enhancement layer includes a first perpendicular enhancement sublayer formed adjacent to said first magnetic free layer and a second perpendicular enhancement sublayer formed adjacent to said second magnetic free layer.

17. The MTJ memory element of claim 16 , wherein said first magnetic free layer is made of an alloy comprising cobalt, iron, and boron.

18. The MTJ memory element of claim 16 , wherein said first perpendicular enhancement sublayer is made of tungsten or molybdenum.

19. The MTJ memory element of claim 16 , wherein said second perpendicular enhancement sublayer is made of tantalum or hafnium.

20. The MTJ memory element of claim 16 , wherein said second perpendicular enhancement sublayer is made of zirconium or niobium.

21. The MTJ memory element of claim 16 , wherein said non-magnetic perpendicular enhancement layer further includes a third perpendicular enhancement sublayer formed between said first and second perpendicular enhancement sublayers.

22. The MTJ memory element of claim 21 , wherein said first and second perpendicular enhancement sublayers are made of molybdenum or tungsten, said third perpendicular enhancement sublayer is made of tantalum or hafnium.