Precessional spin current magnetic tunnel junction devices and methods of manufacture

1. A method of fabricating a Magnetic Tunnel Junction (MTJ) device comprising:

depositing a first Precessional Spin Current (PSC) magnetic layer on a MTJ formation, wherein the first PSC magnetic layer includes Iron (Fe);

depositing a second PSC magnetic layer on the first PSC magnetic layer, wherein the second PSC magnetic layer includes Ruthenium (Ru);

etching at least a portion of the second PSC magnetic layer with a first etch process to smooth the surface of the Ruthenium (Ru) of the second PSC magnetic layer as deposited;

depositing a third PSC magnetic layer on the second PSC magnetic layer after the first etch of the second PSC magnetic layer, wherein the third PSC magnetic layer includes one or more of Cobalt (Co), Iron (Fe) and Boron (B); and

depositing a capping layer on the third magnetic layer.

2. The method of fabricating the MTJ device according to claim 1 , wherein:

the first PSC magnetic layer has a deposited thickness of approximately 0.4-1.0 nanometers (nm);

the second PSC magnetic layer has a deposited thickness of approximately 0.5-3.0 nm after the first etch of the second PSC magnetic layer; and

the third PSC magnetic layer has a deposited thickness of approximately 1-5 nm.

3. The method of fabricating the MTJ device according to claim 1 , wherein:

the first and second PSC magnetic layers are deposited in a first vacuum instance; and

the second PSC magnetic layer is etched and the third PSC magnetic layer and the capping layer are deposited in a second vacuum instance.

4. The method of fabricating the MTJ device according to claim 3 , further comprising:

annealing the MTJ formation after depositing the first and second PSC magnetic layers and before etching the second PSC magnetic layer.

5. The method of fabricating the MTJ device according to claim 4 , further comprising:

depositing an intermediate capping layer on the second PSC magnetic layer in the first vacuum instance; and

etching the intermediate capping layer with a second etch in the second vacuum instance, wherein the second etch and the first etch comprise a two-step etching process where the second etch is faster than the first etch.

6. The method of fabricating the MTJ device according to claim 3 , further comprising:

depositing a PSC coupling layer in the first vacuum instance, wherein the PSC coupling layer is disposed between the first PSC magnetic layer and the MTJ formation.

7. The method of fabricating the MTJ device according to claim 3 , further comprising:

depositing a Perpendicular Magnetic Anisotropy (PMA) enhancement layer in the first vacuum instance, wherein the PMA enhancement layer is disposed between the first PSC magnetic layer and the MTJ formation.

8. The method of fabricating the MTJ device according to claim 6 , further comprising:

depositing a reference magnetic layer of the MTJ formation in the first vacuum instance, wherein the reference magnetic layer is disposed on a substrate;

depositing a non-magnetic tunneling barrier layer of the MTJ formation in the first vacuum instance, wherein the non-magnetic tunneling barrier layer is disposed on the reference magnetic layer; and

depositing a free magnetic layer of the MTJ formation in the first vacuum instance, wherein the free magnetic layer is disposed on the non-magnetic tunneling barrier layer.

9. The method of fabricating the MTJ device according to claim 8 , wherein:

the reference magnetic layer includes one or more of Cobalt (Co), Iron (Fe), Boron (B), Cobalt Nickel (CoNi), Cobalt Platinum (CoPt), and has a deposited thickness of approximately 1-5 nanometers (nm);

the non-magnetic tunneling barrier layer includes Magnesium (Mg) oxide, and has a deposited thickness of approximately 1-10 nm; and

the free magnetic layer includes one or more of Cobalt (Co), Iron (Fe) and Boron (B), and has a deposited thickness of approximately 1-3 nm.

10. The method of fabricating the MTJ device according to claim 8 , further comprising:

depositing a first ferromagnetic layer of a Synthetic Antiferromagnetic (SAF) formation in the first vacuum instance, wherein the first ferromagnetic layer is disposed on the substrate; and

depositing a first non-magnetic layer of the SAF formation in the first vacuum instance, wherein the first non-magnetic layer is disposed between the first ferromagnetic layer and the reference magnetic layer.

11. The method of fabricating the MTJ device according to claim 10 , wherein

the first ferromagnetic layer includes one or more of Cobalt (Co), Cobalt Nickel (CoNi) and Cobalt Platinum (CoPt), and has a deposited thickness of approximately 1-5 nm; and

the first non-magnetic layer includes Ruthenium (Ru), and has a deposited thickness of approximately 0.9 nm.

12. The method of fabricating the MTJ device according to claim 11 , further comprising:

depositing a seed layer in the first vacuum instance, wherein the seed layer is disposed between the substrate and the first ferromagnetic layer.

13. The method of fabricating the MTJ device according to claim 1 , wherein the MTJ device comprises a Magnetoresistive Random Access Memory (MRAM).

14. A method of fabricating a Magnetic Tunnel Junction (MTJ) device comprising:

receiving a wafer including a first Precessional Spin Current (PSC) magnetic layer disposed on a MTJ formation and a second PSC magnetic layer disposed on the first PSC magnetic, wherein the first PSC magnetic layer includes Iron (Fe) and the second PSC magnetic layer includes Ruthenium (Ru);

etching at least a first portion of the second PSC magnetic layer with a first etch process to remove the first portion of the second PSC magnetic layer;

etching at least a second portion of the second PSC magnetic layer with a second etch process to smooth the surface of the Ruthenium (Ru) of the second PSC magnetic layer as deposited, wherein the second etch process is slower than the first etch process;

depositing a third PSC magnetic layer on the second PSC magnetic layer after the second etch of the second PSC magnetic layer, wherein the third PSC magnetic layer includes one or more of Cobalt (Co), Iron (Fe) and Boron (B); and

depositing a capping layer on the third magnetic layer.

15. The method of fabricating the MTJ device according to claim 14 , further comprising:

annealing the wafer before etching at least the first portion of the second PSC magnetic layer.

16. The method of fabricating the MTJ device according to claim 14 , wherein:

the first PSC magnetic layer has a deposited thickness of approximately 0.4-1.0 nanometers (nm);

the second PSC magnetic layer has a deposited thickness of approximately 0.5-3.0 nm after the second etch of the second PSC magnetic layer; and

the third PSC magnetic layer has a deposited thickness of approximately 1-5 nm.