Low-crystallization temperature MTJ for spin-transfer torque magnetic random access memory (STTMRAM)
View Patent ↗A spin-torque transfer memory random access memory (STTMRAM) element is disclosed and has a fixed layer, a barrier layer formed upon the fixed layer, and a free layer comprised of a low-crystallization temperature alloy of CoFeB—Z where Z is below 25 atomic percent of one or more of titanium, (Ti), yittrium (Y), zirconium (Zr), and vanadium (V), wherein during a write operation, a bidirectional electric current is applied across the STTMRAM element to switch the magnetization of the free layer between parallel and anti-parallel states relative to the magnetization of the fixed layer.
1. A spin-torque transfer memory random access memory (STTMRAM) element, employed in a STTMRAM array, where the STTMRAM element received electric current for storage of digital information, the STTMRAM element comprising:
a magnetic tunnel junction (MTJ) including,
an anti-ferromagnetic (AF) layer;
a fixed layer having a magnetization that is substantially fixed in one direction and that comprises a first magnetic layer, an AF coupling layer and a second magnetic layer;
a barrier layer formed upon the fixed layer;
a free layer comprised of a low-crystallization temperature magnetization layer made of an alloy of CoFeB—Z where Z is made of one or more of titanium, (Ti), yittrium (Y), zirconium (Zr), and vanadium (V), the free layer having a magnetization that is switchable;
wherein during a write operation, a bidirectional electric current is applied across the STTMRAM element to switch the magnetization of the free layer between parallel and anti-parallel states relative to the magnetization of the fixed layer.
2. The STTMRAM element, as recited in claim 1 , further including a cap layer formed on top of the free layer of the MTJ.
3. The STTMRAM element, as recited in claim 2 , further including an underlayer on top of which is formed the an anti-ferromagnetic (AF) coupling layer.
4. The STTMRAM element, as recited in claim 3 , wherein the underlayer is made of tantalum (Ta).
5. The STTMRAM element, as recited in claim 3 , wherein the AF coupling layer is made of platinum manganese (PtMn), iridium manganese (IrMn), nickel manganese (NiMn) or iron manganese (FeMn).
6. The STTMRAM element, as recited in claim 1 , wherein the first and second magnetic layers of the fixed layer each have ferromagnetic characteristic and an anti-parallel magnetization orientation relative to each other.
7. The STTMRAM element, as recited in claim 1 , wherein the first and second magnetic layers of the fixed layer are each ferromagnetic and separated from each other by ruthenium (Ru).
8. The STTMRAM element, as recited in claim 1 , wherein the free layer further includes a third magnetic layer formed between the low-crystallization temperature magnetization layer and the barrier layer.
9. The STTMRAM element, as recited in claim 8 , wherein the third magnetic layer is made of the alloy cobolt iron boron (CoFeB) and the low-crystallization temperature magnetization layer is made of titanium (Ti).
10. The STTMRAM element, as recited in claim 8 , wherein the third magnetic layer and the low-crystallization temperature magnetization layer are made of the Co30Fe40B20Ti10.
11. The STTMRAM element, as recited in claim 8 , wherein the low-crystallization temperature magnetization layer is made of Ti, Zr, V or Y.
12. The STTMRAM element, as recited in claim 8 , wherein the fixed layer is synthetic.
13. The STTMRAM element, as recited in claim 12 , wherein the fixed layer is made of cobolt iron/ruthenium/cobolt iron boron (CoFe/Ru/CoFeB) alloy.
14. The STTMRAM element, as recited in claim 1 , wherein the barrier layer is made of one or more of the materials: magnesium oxide, ruthenium oxide, strontium oxide, zinc oxide, aluminum oxide, and titanium oxide.
15. A system including a spin-torque transfer memory random access memory (STTMRAM) element, the STTMRAM element employed in a STTMRAM array, where the STTMRAM element received electric current for storage of digital information, the STTMRAM element comprising:
a magnetic tunnel junction (MTJ) including,
an anti-ferromagnetic (AF) layer;
a fixed layer having a magnetization that is substantially fixed in one direction and that comprises a first magnetic layer, an AF coupling layer and a second magnetic layer;
a barrier layer formed upon the fixed layer;
a free layer comprised of a low-crystallization temperature magnetization layer made of an alloy of CoFeB—Z where Z is made of one or more of titanium, (Ti), yittrium (Y), zirconium (Zr), and vanadium (V), the free layer having a magnetization that is switchable;
wherein during a write operation, a bidirectional electric current is applied across the STTMRAM element to switch the magnetization of the free layer between parallel and anti-parallel states relative to the magnetization of the fixed layer.
16. The system, as recited in claim 15 , wherein the system is a hand-held consumer device.
17. The system, as recited in claim 15 , wherein the system is a laptop.
18. The system, as recited in claim 15 , wherein the system is a set-top-box.
19. The system, as recited in claim 15 , wherein the system is a microprocessor.