Three-Dimensional Arrays with Magnetic Tunnel Junction Devices Including an Annular Free Magnetic Layer and a Planar Reference Magnetic Layer

1 . A device comprising:

a first plurality of annular structures, each annular structure including an annular non-magnetic layer disposed about an annular conductive layer, an annular free magnetic layer disposed about the annular non-magnetic layer, and an annular tunnel insulator disposed about the annular free magnetic layer;

a first planar reference magnetic layer disposed about the first plurality of annular structures and separated from the free magnetic layers of the first plurality of annular structures by the annular tunnel barrier layers of the first plurality of annular structures;

a first non-magnetic insulator layer disposed about the first plurality of annular structures and on a first side of the first planar reference magnetic layer;

a second non-magnetic insulator layer disposed about the first plurality of annular structures and on a second side of the first planar reference magnetic layer;

a second plurality of annular structures axially aligned with respective ones the first plurality of annular structures;

a second planar reference magnetic layer disposed about the second plurality of annular structures and separated from the free magnetic layer of the second plurality of annular structures by the annular tunnel barrier layers of the second plurality of annular structures;

a third non-magnetic insulator layer disposed about the second plurality of annular structures and between the second non-magnetic insulator layer and a first side of the second planar reference magnetic layer; and

a fourth non-magnetic insulator layer disposed about the second plurality of annular structures and on a second side of the second planar reference magnetic layer.

2 . The device of claim 1 , further comprising:

a third plurality of annular structures;

a third planar reference magnetic layer disposed about the third plurality of annular structures and separated from the free magnetic layer of the third plurality of annular structures by the annular tunnel barrier layers of the third plurality of annular structures;

a fifth non-magnetic insulator layer disposed about the third plurality of annular structures and between the fourth non-magnetic insulator layer and a first side of the third planar reference magnetic layer; and

a sixth non-magnetic insulator layer disposed about the third plurality of annular structures and on a second side of the third planar reference magnetic layer.

3 . The device of claim 1 , further comprising:

a non-magnetic metal layer disposed between the second non-magnetic insulator layer and the third non-magnetic insulator layer and between the first plurality of annular structures and the second plurality of annular structures.

4 . The device of claim 1 , further comprising:

an additional non-magnetic insulator layer disposed between the second non-magnetic insulator layer and the third non-magnetic insulator layer; and

a non-magnetic metal plug disposed between respective ones of the annular conductive layer of the first plurality of annular structures and the annular conductive layer of the second plurality of annular structures.

5 . The device of claim 1 , wherein each annular structure comprises a conical structure including a conical non-magnetic layer disposed about a conical portion of the conductive layer, a conical free magnetic layer disposed about the conical non-magnetic layer, and a conical tunnel barrier layer disposed about the conical free magnetic layer.

6 . The device of claim 5 , wherein each conical structure has a taper of approximately 10-45 degrees from a first side of the planar reference magnetic layer to a second side of the planar reference magnetic layer.

7 . The device of claim 1 , further comprising:

the plurality of annular structures arranged in columns and rows in the first and second planar reference magnetic layers; and

a plurality of insulator regions disposed in the first and second planar reference magnetic layers between a respective pair of columns of the plurality of annular structures.

8 . The device of claim 1 , wherein,

a magnetic field of the first and second planar reference magnetic layers has a fixed polarization substantially perpendicular to a major planar orientation of the first and second planar reference magnetic layers;

a magnetic field of the annular free magnetic layer of each of the first plurality of annular structures has a polarization substantially perpendicular to the major planar orientation of the first planar reference magnetic layer and selectively switchable between being substantially parallel and substantially antiparallel to the magnetic field of the first planar reference layer; and

a magnetic field of the annular free magnetic layer of each of the second plurality of annular structures has a polarization substantially perpendicular to the major planar orientation of the second planar reference magnetic layer and selectively switchable between being substantially parallel and substantially antiparallel to the magnetic field of the second planar reference layer.

9 . The device of claim 9 , wherein,

the magnetic field of the annular free magnetic layer of each of the first plurality of annular structures is configured to switch to being substantially parallel to the magnetic field of the first planar reference layer in response to a current flow in a first direction through the conductive annular layer of the first plurality annular structures and to switch to being substantially anti-parallel to the magnetic field of the first planar reference layer in response to a current flow in a second direction through the conductive annular layer of the first plurality of annular structures; and

the magnetic field of the annular free magnetic layer of each of the second plurality of annular structures is configured to switch to being substantially parallel to the magnetic field of the second planar reference layer in response to a current flow in a first direction through the conductive annular layer of the second plurality annular structures and to switch to being substantially anti-parallel to the magnetic field of the second planar reference layer in response to a current flow in a second direction through the conductive annular layer of the second plurality of annular structures.

10 . A memory device comprising:

an array of Magnetic Tunnel Junction (MTJ) cells including;

a first plurality of annular structures arranged in columns and rows, each annular structure including an annular non-magnetic layer disposed about an annular conductive layer, an annular free magnetic layer disposed about the annular non-magnetic layer, and an annular tunnel insulator disposed about the annular free magnetic layer;

a first planar reference magnetic layer disposed about the first plurality of annular structures and separated from the free magnetic layers of the first plurality of annular structures by the annular tunnel barrier layers of the first plurality of annular structures;

a first non-magnetic insulator layer disposed about the first plurality of annular structures and on a first side of the first planar reference magnetic layer;

a second non-magnetic insulator layer disposed about the first plurality of annular structures and on a second side of the first planar reference magnetic layer;

a second plurality of annular structures axially aligned with respective ones the first plurality of annular structures;

a second planar reference magnetic layer disposed about the second plurality of annular structures and separated from the free magnetic layer of the second plurality of annular structures by the annular tunnel barrier layers of the second plurality of annular structures;

a third non-magnetic insulator layer disposed about the second plurality of annular structures and between the second non-magnetic insulator layer and a first side of the second planar reference magnetic layer; and

a fourth non-magnetic insulator layer disposed about the second plurality of annular structures and on a second side of the second planar reference magnetic layer.

11 . The memory device of claim 10 , further comprising:

a non-magnetic metal layer disposed between the second non-magnetic insulator layer and the third non-magnetic insulator layer and between the first plurality of annular structures and the second plurality of annular structures.

12 . The memory device of claim 10 , further comprising:

a non-magnetic insulator layer disposed between the second set of one or more additional layers and the third set of one or more additional layers; and

a non-magnetic metal plug disposed between respective ones of the annular conductive layer of the first plurality of annular structures and the annular conductive layer of the second plurality of annular structures.

13 . The memory device of claim 10 , wherein,

a magnetic field of the first and second planar reference magnetic layers has a fixed polarization substantially perpendicular to a major planar orientation of the first and second planar reference magnetic layers;

a magnetic field of the annular free magnetic layer of each of the first plurality of annular structures has a polarization substantially perpendicular to the major planar orientation of the first planar reference magnetic layer and selectively switchable between being substantially parallel and substantially antiparallel to the magnetic field of the first planar reference layer; and

a magnetic field of the annular free magnetic layer of each of the second plurality of annular structures has a polarization substantially perpendicular to the major planar orientation of the second planar reference magnetic layer and selectively switchable between being substantially parallel and substantially antiparallel to the magnetic field of the second planar reference layer.

14 . The memory device of claim 13 , wherein,

the magnetic field of the annular free magnetic layer of each of the first plurality of annular structures is configured to switch to being substantially parallel to the magnetic field of the first planar reference layer in response to a current flow in a first direction through the conductive annular layer of the first plurality of annular structures and to switch to being substantially anti-parallel to the magnetic field of the first planar reference layer in response to a current flow in a second direction through the conductive annular layer of the first plurality of annular structures; and

the magnetic field of the annular free magnetic layer of each of the second plurality of annular structures is configured to switch to being substantially parallel to the magnetic field of the second planar reference layer in response to a current flow in a first direction through the conductive annular layer of the second plurality annular structures and to switch to being substantially anti-parallel to the magnetic field of the second planar reference layer in response to a current flow in a second direction through the conductive annular layer of the second plurality of annular structures.

15 . The memory device of claim 10 , further comprising:

the plurality of annular structures arranged in columns and rows in the first and second planar reference magnetic layers; and

a plurality of insulator regions disposed in the first and second planar reference magnetic layers between a respective pair of columns of the plurality of annular structures.

16 . A memory device comprising:

an array of Magnetic Tunnel Junction (MTJ) cells arranged in cell columns and cell rows in a plurality of cell levels, wherein the MTJ cells in corresponding cell column and cell row positions in the plurality of cell levels are coupled together in cell strings, each MTJ cell includes;

an annular structure including an annular non-magnetic layer disposed about an annular conductive layer, an annular free magnetic layer disposed about the annular non-magnetic layer, and an annular tunnel insulator disposed about the annular free magnetic layer;

a portion of a respective planar reference magnetic layer disposed about the annular structure;

a portion of a respective planar non-magnetic insulator layer disposed on a first side of the planar reference magnetic layer and about the annular structure;

a portion of another respective planar non-magnetic insulator layer disposed on a second side of the planar reference magnetic layer and about the annular structure; and

a plurality of select elements arranged in select columns and select rows, wherein respective selector elements are coupled to respective strings of MTJ cells in corresponding cell column and cell row positions.

17 . The memory device of claim 18 , further comprising:

a plurality of blocks of the array of MTJ cells arranged in block columns and block rows.

18 . The memory device of claim 16 , wherein the annular structure comprises a conical structure including a conical non-magnetic layer disposed about a conical portion of the conductive layer, a conical free magnetic layer disposed about the conical non-magnetic layer, and a conical tunnel barrier layer disposed about the conical free magnetic layer.

19 . The memory device of claim 16 , wherein,

a magnetic field of the planar reference magnetic layer has a fixed polarization substantially perpendicular to a major planar orientation of the planar reference magnetic layer; and

a magnetic field of the annular free magnetic layer has a polarization substantially perpendicular to the major planar orientation of the planar reference magnetic layer and selectively switchable between being substantially parallel and substantially antiparallel to the magnetic field of the planar reference layer.

20 . The memory device of claim 19 , wherein the magnetic field of the annular free magnetic layer is configured to switch to being substantially parallel to the magnetic field of the planar reference layer in response to a current flow in a first direction through the conductive annular layer and to switch to being substantially anti-parallel to the magnetic field of the planar reference layer in response to a current flow in a second direction through the conductive annular layer.