Magnetic device and magnetic random access memory
A magnetic memory including a first spin-orbital-transfer-spin-torque-transfer (SOT-SIT) hybrid magnetic device disposed over a substrate, a second SOT-STT hybrid magnetic device disposed over the substrate, and a SOT conductive layer connected to the first and second SOT-STT hybrid magnetic devices. Each of the first and second SOT-STT hybrid magnetic devices includes a first magnetic layer, as a magnetic free layer, a spacer layer disposed under the first magnetic layer, and a second magnetic layer, as a magnetic reference layer, disposed under the spacer layer. The SOT conductive layer is disposed over the first magnetic layer of each of the first and second SOT-STT hybrid magnetic devices.
1. A magnetic memory, comprising:
first word lines;
a second word line;
a bit line;
a source line;
memory cells; and
a conductive wire, wherein:
each of the memory cells includes a magnetic-tunneling-junction (MTJ) film stack and a spin-torque-transfer (STI) switching device,
one terminal of the STT switching device is coupled to one end of the MTJ film stack, another terminal of the STT switching device is coupled to the source line and a control terminal of the SIT switching device is coupled to corresponding one of the first word lines,
another end of the MTJ film stack is coupled to the conductive wire,
the conductive wire is coupled to the bit line,
the magnetic memory further comprises a SOT switching device,
one terminal of the SOT switching device is coupled to the conductive wire, another terminal of the SOT switching device is coupled to the source line and a control terminal of the SOT switching device is coupled to the second word line,
the MTJ film stack includes:
a first magnetic layer, as a magnetic free layer;
a spacer layer disposed under the first magnetic layer; and
a second magnetic layer, as a magnetic reference layer, disposed under the spacer layer, and
the conductive wire is disposed over the first magnetic layer.
2. The magnetic memory of claim 1 , wherein the source line is coupled to a current source.
3. The magnetic memory of claim 1 , wherein a number of the memory cells coupled to the conductive wire is in a range from 2 to 32.
4. The magnetic memory of claim 1 , further comprising driver circuitry configured to:
apply a SOT current to the conductive wire by turning on the SOT switching device; and
thereafter, apply a SIT current to one of the memory cells by turning on the Sri′ switching device coupled to the one of the memory cells, thereby writing data to the one of the memory cells.
5. The magnetic memory of claim 4 , wherein the driver circuitry configured to:
turn off the STT switching device coupled to the one of the memory cells; and
thereafter turn off the SOT switching device.
6. The magnetic memory of claim 1 , wherein the conductive wire includes one or more layers of W, Ta, Mo and IrMn.
7. The magnetic memory of claim 1 , wherein the conductive wire includes a bottom layer made of W, Ta or Mo, and a top layer made of IrMn.
8. The magnetic memory of claim 1 , further comprising an upper electrode layer disposed in contact with the conductive wire.
9. The magnetic memory of claim 8 , wherein the upper electrode layer includes a narrow portion having a width narrower than a remaining portion or a thin portion having a thickness smaller than the remaining portion over each of the memory cells the remaining portion being disposed between adjacent two magnetic cells.
10. The magnetic memory of claim 8 , wherein the MTJ film stack further comprises an interfacial layer disposed over the first magnetic layer and in contact with the conductive wire.
11. The magnetic memory of claim 8 , wherein the first magnetic layer is Fe x Co y B 1-x-y, 0.50<x<0.70 and 0.10<y<0.30.
12. The magnetic memory of claim 11 , wherein the second magnetic layer includes at least one of a layer of Co, Fe and B, and a layer of Fe and B.
13. The magnetic memory of claim 12 , wherein:
the MTJ film stack further comprises a third magnetic layer, as a bias layer, under the second magnetic layer, and
the third magnetic layer includes a layer of Co and Fe.
14. A magnetic memory, comprising:
first word lines;
a second word line;
a bit line;
a source line;
memory cells; and
a conductive wire, wherein:
each of the memory cells includes a magnetic-tunneling-junction (MTJ) film stack and a spin-torque-transfer (SIT) switching device,
one terminal of the STT switching device is coupled to one end of the MTJ film stack, another terminal of the STT switching device is coupled to the source line and a control terminal of the STT switching device is coupled to corresponding one of the first word lines,
another end of the MTJ film stack is coupled to the conductive wire,
the conductive wire is coupled to the bit line,
the magnetic memory further comprises a SOT switching device,
one terminal of the SOT switching device is coupled to the conductive wire, another terminal of the SOT switching device is coupled to the source line and a control terminal of the SOT switching device is coupled to the second word line, and
a number of the memory cells coupled to the conductive wire is in a range from 2 to 32.
15. The magnetic memory of claim 14 , wherein the conductive wire includes one or more layers of W, Mo and IrMn.
16. The magnetic memory of claim 14 , wherein the conductive wire includes a bottom layer made of W, Ta or Mo, and a top layer made of IrMn.
17. The magnetic memory of claim 14 , further comprising an upper electrode layer disposed in contact with the conductive wire,
wherein the upper electrode layer includes a narrow portion having a width narrower than a remaining portion or a thin portion having a thickness smaller than the remaining portion over each of the memory cells the remaining portion being disposed between adjacent two magnetic cells.
18. A magnetic memory, comprising:
first word lines;
a second word line;
a bit line;
a source line;
memory cells; and
a conductive wire, wherein:
each of the memory cells includes a magnetic-tunneling-junction (MTJ) film stack and a spin-torque-transfer (STT) switching device,
one terminal of the STT switching device is coupled to one end of the MTJ film stack, another terminal of the STT switching device is coupled to the source line and a control terminal of the STT switching device is coupled to corresponding one of the first word lines,
another end of the MTJ film stack is coupled to the conductive wire,
the conductive wire is coupled to the bit line,
the magnetic memory further comprises a SOT switching device,
one terminal of the SOT switching device is coupled to the conductive wire, another terminal of the SOT switching device is coupled to the source line and a control terminal of the SOT switching device is coupled to the second word line, and
the magnetic memory further comprises driver circuitry configured to:
apply a SOT current to the conductive wire by turning on the SOT switching device; and
thereafter, apply a SIT current to one of the memory cells by turning on the Sri′ switching device coupled to the one of the memory cells, thereby writing data to the one of the memory cells.
19. The magnetic memory of claim 18 , wherein the driver circuitry configured to:
turn off the STT switching device coupled to the one of the memory cells; and
thereafter turn off the SOT switching device.
20. The magnetic memory of claim 18 , wherein a number of the memory cells coupled to the conductive wire is in a range from 2 to 128.