Magnetic memory device

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2017-176435, filed on Sep. 14, 2017; the entire contents of which are incorporated herein by reference.

Embodiments described herein relate generally to a magnetic memory device.

There is a magnetic memory device that uses a magnetic layer. Stable operations of the magnetic memory device are desirable.

FIG. 1A and FIG. 1B are schematic perspective views illustrating a magnetic memory device according to a first embodiment;

FIG. 2 is a schematic view illustrating a material of the magnetic memory device according to the first embodiment;

FIG. 3A and FIG. 3B are schematic views illustrating the material of the magnetic memory device according to the first embodiment;

FIG. 4 is a schematic perspective view illustrating another magnetic memory device according to the first embodiment;

FIG. 5 is a schematic perspective view illustrating another magnetic memory device according to the first embodiment;

FIG. 6 is a schematic perspective view illustrating another magnetic memory device according to the first embodiment;

FIG. 7 is a schematic perspective view illustrating another magnetic memory device according to the first embodiment;

FIG. 8 is a schematic perspective view illustrating a magnetic memory device according to the second embodiment;

FIG. 9 is a schematic perspective view illustrating another magnetic memory device according to the second embodiment;

FIG. 10 is a schematic cross section illustrating a magnetic memory device according to a third embodiment;

FIG. 11 is a schematic cross section illustrating another magnetic memory device according to the third embodiment;

FIG. 12 is a schematic cross section illustrating another magnetic memory device according to the third embodiment;

FIG. 13 is a schematic perspective view illustrating a magnetic memory device according to a fourth embodiment;

FIG. 14 is a schematic perspective view illustrating another magnetic memory device according to the fourth embodiment;

FIG. 15A to FIG. 15C are schematic perspective views illustrating a magnetic memory device according to a fifth embodiment;

FIG. 16A to FIG. 16C are schematic perspective views illustrating another magnetic memory device according to the fifth embodiment; and

FIG. 17 is a schematic view showing a magnetic memory device according to a sixth embodiment.

According to one embodiment, a magnetic memory device includes a conductive layer, a first magnetic layer, a second magnetic layer, a first nonmagnetic layer, and a controller. The conductive layer includes a first portion, a second portion, and a third portion between the first portion and the second portion. The conductive layer includes a first metal and boron. The first magnetic layer is separated from the third portion in a first direction crossing a second direction. The second direction is from the first portion toward the second portion. The second magnetic layer is provided between the third portion and the first magnetic layer. The first nonmagnetic layer is provided between the first magnetic layer and the second magnetic layer. The controller is electrically connected to the first portion and the second portion. The controller is configured to supply a current to the conductive layer. The first metal includes at least one selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

Various embodiments will be described hereinafter with reference to the accompanying drawings.

The drawings are schematic and conceptual; and the relationships between the thickness and width of portions, the proportions of sizes among portions, etc., are not necessarily the same as the actual values thereof. Further, the dimensions and proportions may be illustrated differently among drawings, even for identical portions.

In the specification and drawings, components similar to those described or illustrated in a drawing thereinabove are marked with like reference numerals, and a detailed description is omitted as appropriate.

First Embodiment

FIG. 1A and FIG. 1B are schematic perspective views illustrating a magnetic memory device according to a first embodiment.

As shown in FIG. 1A , the magnetic memory device 110 according to the embodiment includes a conductive layer 20 , a first magnetic layer 11 , a second magnetic layer 12 , a first nonmagnetic layer 11 n , and a controller 70 .

The conductive layer 20 includes a first portion 20 a , a second portion 20 b , and a third portion 20 c . The third portion 20 c is positioned between the first portion 20 a and the second portion 20 b.

The conductive layer 20 includes a first metal and boron. The first metal includes at least one selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. The conductive layer 20 may be, for example, nonmagnetic.

The first magnetic layer 11 is separated from the third portion 20 c in a first direction. The first direction crosses a direction (a second direction) from the first portion 20 a toward the second portion 20 b.

The first direction is taken as a Z-axis direction. One direction perpendicular to the Z-axis direction is taken as an X-axis direction. A direction perpendicular to the Z-axis direction and the X-axis direction is taken as a Y-axis direction. In the example, the second direction is the X-axis direction.

The second magnetic layer 12 is provided between the third portion 20 c and the first magnetic layer 11 . The second magnetic layer 12 is electrically connected to the third portion 20 c . The first nonmagnetic layer 11 n is provided between the first magnetic layer 11 and the second magnetic layer 12 . Another layer may be provided between the first nonmagnetic layer 11 n and the first magnetic layer 11 . Another layer may be provided between the first nonmagnetic layer 11 n and the second magnetic layer 12 .

The first magnetic layer 11 functions as, for example, a reference layer. The second magnetic layer 12 functions as, for example, a memory layer (e.g., a free layer). A second magnetization 12 M of the second magnetic layer 12 changes more easily than a first magnetization 11 M of the first magnetic layer 11 . The orientation of the second magnetization 12 M of the second magnetic layer 12 corresponds to information that is stored. For example, the orientation of the magnetization corresponds to the orientation of the easy magnetization axis.

The first magnetic layer 11 , the first nonmagnetic layer 11 n , and the second magnetic layer 12 are included in a first stacked body SB 1 . The first stacked body SB 1 functions as, for example, at least a portion of one memory cell MC. The first stacked body SB 1 has, for example, a magnetic tunnel junction (MTJ). The first stacked body SB 1 corresponds to a MTJ element.

In the example, the easy magnetization axis of the second magnetic layer 12 crosses the first direction (e.g., the Z-axis direction). The second magnetic layer 12 is an in-plane magnetization film.

In the example, a length Ly along a third direction of the first magnetic layer 11 is longer than a length Lx along the second direction of the first magnetic layer 11 . The third direction crosses a plane including the first direction and the second direction. The third direction is, for example, the Y-axis direction. Shape anisotropy occurs in the first magnetic layer 11 and the second magnetic layer 12 . For example, the first magnetization 11 M of the first magnetic layer 11 is aligned with the Y-axis direction. For example, the second magnetization 12 M of the second magnetic layer 12 is oriented in the +Y direction or the −Y direction. In other examples of the embodiment as described below, the relationship between the length Ly and the length Lx is arbitrary. In the embodiment, the orientation of the magnetization is arbitrary.

In the example, the first magnetic layer 11 is, for example, an in-plane magnetization film. For example, the first magnetization 11 M of the first magnetic layer 11 crosses the first direction (the Z-axis direction). In the example, the first magnetization 11 M of the first magnetic layer 11 is aligned with the third direction (e.g., the Y-axis direction, i.e., a direction crossing a plane including the first direction and the second direction). For example, the orientation of the first magnetization 11 M in the X-Y plane is arbitrary.

The controller 70 is electrically connected to the first portion 20 a and the second portion 20 b . The controller 70 supplies a current to the conductive layer 20 . In the example, the controller 70 includes a control circuit 75 . The control circuit 75 (the controller 70 ) and the first portion 20 a are electrically connected by an interconnect 70 b . The control circuit 75 (the controller 70 ) and the second portion 20 b are electrically connected by an interconnect 70 c . In the example, a switch SwS 1 is provided in a current path (the interconnect 70 b ) between the control circuit 75 and the first portion 20 a . The gate (the control terminal) of the switch SwS 1 is electrically connected to the control circuit 75 .

In the example, the control circuit 75 (the controller 70 ) is electrically connected to the first magnetic layer 11 . The control circuit 75 (the controller 70 ) and the first magnetic layer 11 are electrically connected by an interconnect 70 a . In the example, a switch Sw 1 is provided in a current path (the interconnect 70 a ) between the control circuit 75 and the first magnetic layer 11 . The gate (the control terminal) of the switch Sw 1 is electrically connected to the control circuit 75 .

These switches may be included in the controller 70 . The potentials of the conductive layer 20 and the first stacked body SB 1 are controlled by the controller 70 .

For example, the first portion 20 a is set to a reference potential V 0 ; and a first voltage V 1 (e.g., a select voltage) is applied to the first magnetic layer 11 . At this time, for example, the electrical resistance of the first stacked body SB 1 changes according to the orientation of the current flowing in the conductive layer 20 . On the other hand, the first portion 20 a is set to the reference potential V 0 ; and a second voltage V 2 (e.g., an unselect voltage) is applied to the first magnetic layer 11 . The second voltage V 2 is different from the first voltage V 1 . When the second voltage V 2 is applied, for example, the electrical resistance of the first stacked body SB 1 substantially does not change even in the case where a current flows in the conductive layer 20 . The change of the electrical resistance corresponds to the change of the state of the first stacked body SB 1 . For example, the change of the electrical resistance corresponds to the change of the orientation of the second magnetization 12 M of the second magnetic layer 12 . For example, the second voltage V 2 is different from the first voltage V 1 . For example, the absolute value of the potential difference between the reference potential V 0 and the first voltage V 1 is greater than the absolute value of the potential difference between the reference potential V 0 and the second voltage V 2 . For example, the polarity of the first voltage V 1 may be different from the polarity of the second voltage V 2 . Such an electrical resistance difference is obtained by a control of the controller 70 .

For example, the controller 70 performs a first operation and a second operation. These operations are operations when the select voltage is applied to the stacked body SB 1 . In the first operation, the controller 70 supplies a first current Iw 1 to the conductive layer 20 from the first portion 20 a toward the second portion 20 b (referring to FIG. 1A ). In the second operation, the controller 70 supplies a second current Iw 2 to the conductive layer 20 from the second portion 20 b toward the first portion 20 a (referring to FIG. 1A ).

The first electrical resistance between the first magnetic layer 11 and the first portion 20 a after the first operation is different from the second electrical resistance between the first magnetic layer 11 and the first portion 20 a after the second operation. For example, such an electrical resistance difference corresponds to the change of the orientation of the second magnetization 12 M of the second magnetic layer 12 . For example, the orientation of the second magnetization 12 M changes due to the current (a write current) flowing through the conductive layer 20 . For example, it is considered that this is based on the spin Hall effect. For example, it is considered that the change of the orientation of the second magnetization 12 M is based on spin-orbit coupling.

For example, due to the first operation, the second magnetization 12 M has a component having the same orientation as the orientation of the first magnetization 11 M. A “parallel” magnetization is obtained. On the other hand, due to the second operation, the second magnetization 12 M has a component having the reverse orientation of the orientation of the first magnetization 11 M. An “antiparallel” magnetization is obtained. In such a case, the first electrical resistance after the first operation is lower than the second electrical resistance after the second operation. Such an electrical resistance difference corresponds to the information to be stored. For example, the different multiple magnetizations correspond to the information to be stored.

The controller 70 may further implement a third operation and a fourth operation. In the third operation, the potential difference between the first portion 20 a and the first magnetic layer 11 is set to the second voltage V 2 ; and the first current Iw 1 is supplied to the conductive layer 20 . In the fourth operation, the potential difference between the first portion 20 a and the first magnetic layer 11 is set to the second voltage V 2 ; and the second current Iw 2 is supplied to the conductive layer 20 . For example, in the third operation and the fourth operation, the electrical resistance of the first stacked body SB 1 substantially does not change even in the case where a current flows in the conductive layer 20 . The first electrical resistance between the first magnetic layer 11 and the first portion 20 a after the first operation is different from the second electrical resistance between the first magnetic layer 11 and the first portion 20 a after the second operation. The absolute value of the difference between the first electrical resistance and the second electrical resistance is greater than the absolute value of the difference between a third electrical resistance between the first magnetic layer 11 and the first portion 20 a after the third operation and a fourth electrical resistance between the first magnetic layer 11 and the first portion 20 a after the fourth operation.

The second magnetic layer 12 includes at least one selected from the group consisting of Co and Fe. For example, the second magnetic layer 12 includes, for example, Co x1 Fe 1-x1 (0≤x 1 ≤0.6). The second magnetic layer 12 may further include boron (B).

In the embodiment, a thickness t 0 (the length along the first direction (the Z-axis direction)) of the conductive layer 20 is, for example, not less than 2 nanometers (nm) and not more than 11 nm. On the other hand, a thickness tm 2 (the length along the first direction (the Z-axis direction)) of the second magnetic layer 12 is not less than 0.5 nanometers and not more than 3 nanometers. Lattice mismatch occurs effectively when these layers are in the appropriate range. The lattice relaxes easily when the thickness is excessively thick.

As described above, the conductive layer 20 includes boron and the first metal (e.g., at least one selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu). In one example, the concentration of boron in the conductive layer 20 is substantially uniform. In another example, the concentration of boron may change in the conductive layer 20 . One example in which the concentration of boron changes in the thickness direction will now be described.

In a magnetic memory device 110 a as shown in FIG. 1B , the conductive layer 20 includes a first region 21 and a second region 22 . The second region 22 is provided between the first region 21 and the second magnetic layer 12 . For example, the second region 22 physically contacts the second magnetic layer 12 .

The second region 22 includes the first metal and boron. On the other hand, the first region 21 may include the first metal and may not include boron. Or, the first region 21 may include the first metal and boron; and a first concentration of boron in the first region 21 may be lower than a second concentration of boron in the second region 22 . For example, the first region 21 may not include the first metal.

As described below, such a second region 22 may be provided in a portion (the third portion 20 c ) of the conductive layer 20 . For example, the second region 22 may be provided locally in a portion (the third portion 20 c ) including a region overlapping the first stacked body SB 1 in the Z-axis direction. For example, the third portion 20 c includes the first region 21 and the second region 22 . The first portion 20 a and the second portion 20 b may include the first region 21 and may not include the second region 22 .

In the example, the first region 21 extends along the second direction (e.g., the X-axis direction) between the first portion 20 a and the second portion 20 b . The second region 22 extends along the second direction between the first portion 20 a and the second portion 20 b.

As described below, a large spin Hall effect is obtained by providing such a first region 21 and such a second region 22 in the conductive layer 20 .

In the embodiment, a first thickness t 1 along the first direction of the first region 21 is, for example, not less than 1 nanometer and not more than 10 nanometers. A second thickness t 2 along the first direction of the second region 22 is, for example, not less than 1 nanometer and not more than 10 nanometers. The sum of the first thickness t 1 and the second thickness t 2 corresponds to the thickness t 0 (referring to FIG. 1A ).

FIG. 2 is a schematic view illustrating a material of the magnetic memory device according to the first embodiment. FIG. 2 shows an example of the material included in the conductive layer 20 . The conductive layer 20 includes a first metal EL 1 and boron EL 2 . In the case where the first metal EL 1 is Ce, the conductive layer 20 includes CeB 6 . For example, in the case where the first metal EL 1 is Pr, the conductive layer 20 includes PrB 6 . For example, in the case where the first metal EL 1 is Nd, the conductive layer 20 includes Nd B 6 . In the case where the first metal EL 1 is La, the conductive layer 20 includes LaB 6 . In such cases, the material that includes the first metal EL 1 and the boron EL 2 is a hexaboride. Thus, at least a portion of the conductive layer 20 may include a hexaboride.

For example, six borons EL 2 form an octahedron. A boron framework is formed of eight octahedrons. One first metal EL 1 is positioned inside the boron framework. For example, the material that includes the first metal EL 1 and the boron EL 2 has a CsCl crystal structure.

The first metal EL 1 may include at least one selected from the group consisting of Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. Even in such a case, the material that includes the first metal EL 1 and the boron EL 2 is a hexaboride. For example, the material that includes the first metal EL 1 and the boron EL 2 has a CsCl crystal structure.

In the case where the first metal EL 1 is Ce, etc., the first metal EL 1 includes, for example, an electron of the 4 f orbital or the 5 d orbital. For example, a large spin Hall effect occurs between the conductive layer 20 and the second magnetic layer 12 due to the contribution of the interaction between the electron of the 2 p orbital of the boron EL 2 and the electron of the 4 f orbital or the 5 d orbital of the first metal ELL Therefore, a large spin Hall angle θ (absolute value) is obtained.

In the case where the first metal EL 1 is Nd, etc., the first metal EL 1 includes, for example, an electron of the 4 f orbital. For example, a large spin Hall effect occurs between the conductive layer 20 and the second magnetic layer 12 due to the contribution of the interaction between the electron of the 4 f orbital of the first metal EL 1 and the electron of the 2 p orbital of the boron EL 2 . Therefore, a large spin Hall angle θ (the absolute value) is obtained.

Conventionally, an approach is known of using a d-orbital electron such as the electron of the 4 d orbital, the 5 d orbital, etc., as the metal of the conductive layer 20 . In the embodiment, the electron of the 4 f orbital or the electron of the 5 d orbital is used. Thereby, a large spin Hall effect is obtained.

Thereby, the second magnetization 12 M of the second magnetic layer 12 can be controlled stably by the write current (the first current Iw 1 and the second current Iw 2 ) supplied to the conductive layer 20 . For example, the write operation is stable. A magnetic memory device can be provided in which stable operations are possible.

In one example, the first metal EL 1 includes La, Ce, etc. For example, the first metal EL 1 includes a rare-earth element. In such a case, the first metal EL 1 is trivalent (3 + ). In such a case, the material that includes the first metal EL 1 and the boron EL 2 has characteristics close to those of a conductor.

For example, the conductive layer 20 includes at least one selected from the group consisting of CeB 6 , PrB 6 , and NdB 6 in the case where the first metal EL 1 includes at least one selected from the group consisting of Ce, Pr, and Nd. The resistivity is low for these materials. For example, a low resistance is obtained in the conductive layer 20 . In the case where the first metal EL 1 includes La, the conductive layer 20 includes LaB 6 . The resistivity is low for LaB 6 . For example, a low resistance is obtained in the conductive layer 20 .

For example, the first metal EL 1 includes at least one selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. For example, a large spin Hall effect is obtained in the conductive layer 20 in the case where the first metal EL 1 includes two selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. A low resistance is obtained. For example, the conductive layer 20 includes at least one selected from the group consisting of (La, Ce)B 6 , (La, Pr)B 6 , (La, Nd)B 6 , (Ce, Pr)B 6 , (Ce, Nd)B 6 , (Pr, Nd)B 6 , (La, Sm)B 6 , (La, Eu)B 6 , (La, Gd)B 6 , (La, Tb)B 6 , (La, Dy)B 6 , (La, Ho)B 6 , (La, Er)B 6 , (La, Tm)B 6 , (La, Yb)B 6 , (La, Lu)B 6 , (Ce, Sm)B 6 , (Ce, Eu)B 6 , (Ce, Gd)B 6 , (Ce, Tb)B 6 , (Ce, Dy)B 6 , (Ce, Ho)B 6 , (Ce, Er)B 6 , (Ce, Tm)B 6 , (Ce, Yb)B 6 , (Ce, Lu)B 6 , (Pr, Sm)B 6 , (Pr, Eu)B 6 , (Pr, Gd)B 6 , (Pr, Tb)B 6 , (Pr, D Y )B 6 , (Pr, Ho)B 6 , (Pr, Er)B 6 , (Pr, Tm)B 6 , (Pr, Yb)B 6 , (Pr, Lu)B 6 , (Nd, Sm)B 6 , (Nd, Eu)B 6 , (Nd, Gd)B 6 , (Nd, Tb)B 6 , (Nd, Dy)B 6 , (Nd, Ho)B 6 , (Nd, Er)B 6 , (Nd, Tm)B 6 , (Nd, Yb)B 6 , and (Nd, Lu)B 6 . For example, the write operation is stable. A magnetic memory device can be provided in which stable operations are possible.

For example, the current consumption of the write operation can be suppressed. For example, the heat generation, etc., can be suppressed; and the operations are stable.

In one example as recited above, the first metal EL 1 is, for example, a rare-earth element.

The lattice constant of the material including such an element (the first metal EL 1 ) and the boron EL 2 is different from the lattice constant of the material (e.g., CoFe, CoFeB, etc.) included in the second magnetic layer 12 . The lattice length of the second magnetic layer 12 changes from the lattice constant due to the lattice constant difference. Thereby, for example, anisotropy occurs in the second magnetic layer 12 .

FIG. 3A and FIG. 3B are schematic views illustrating the material of the magnetic memory device according to the first embodiment.

FIG. 3A illustrates the lattice of the second magnetic layer 12 in a state without distortion. FIG. 3B illustrates the lattice of the second magnetic layer 12 in a state in which distortion is generated. The lattice constant of the material including the first metal EL 1 and the boron EL 2 (the material of the conductive layer 20 ) is larger than the lattice constant of the material included in the second magnetic layer 12 (e.g., CoFe, CoFeB, etc.). Distortion is generated in the second magnetic layer 12 by the effects of the material including the first metal EL 1 and the boron EL 2 .

As shown in FIG. 2 , the conductive layer 20 is crystalline. As shown in FIG. 3A , the second magnetic layer 12 is, for example, crystalline. The second magnetic layer 12 has a lattice length (a lattice constant Lx 0 ) along one direction crossing the first direction (the Z-axis direction). The second magnetic layer 12 has a lattice length (a lattice constant Lz 0 ) along the first direction. The lattice constant Lx 0 and the lattice constant Lz 0 are the lattice lengths in the state without distortion.

As shown in FIG. 3B , the second magnetic layer 12 is affected by the conductive layer 20 ; and the lattice length of the second magnetic layer 12 changes from the state illustrated in FIG. 3A . In this state, the second magnetic layer 12 has a lattice length Lx 1 along the one direction recited above crossing the first direction (the Z-axis direction). The second magnetic layer 12 has a lattice length Lz 1 along the first direction.

The lattice length Lx 1 (the lattice spacing) of the second magnetic layer 12 along a direction crossing the first direction is longer than the lattice constant Lx 0 of the second magnetic layer 12 along the direction crossing the first direction. The lattice length Lz 1 (the lattice spacing) of the second magnetic layer 12 along the first direction is shorter than the lattice constant Lz 0 of the second magnetic layer 12 along the first direction.

Such a distortion is generated in the second magnetic layer 12 . The distortion is an anisotropic distortion. For example, the magnetic characteristics of the second magnetic layer 12 can be controlled. For example, a voltage effect is obtained.

The conductive layer 20 includes a crystal. For example, the <100> direction of the crystal is aligned with the X-axis direction. The <100> direction of the crystal crosses the first direction (the Z-axis direction). The absolute value of the angle between the <100> direction and the first direction is, for example, not less than 85 degrees and not more than 95 degrees. For example, the (100) plane of the crystal crosses the X-axis direction. For example, the (001) plane of the crystal is aligned with the X-Y plane. The (001) plane of the crystal crosses the first direction. The absolute value of the angle between the (001) plane and the first direction is, for example, not less than 85 degrees and not more than 95 degrees. For example, the conductive layer 20 includes a crystal of the (100) plane.

As described above, the conductive layer 20 includes hexaboride. The concentration of the boron EL 2 in the conductive layer 20 is, for example, 80 atm % or more. The concentration of the boron EL 2 in the conductive layer 20 may be, for example, 85 atm % or more.

As in the magnetic memory device 110 a recited above (referring to FIG. 1B ), the concentration of the boron EL 2 in the second region 22 is not less than 80 atm % in the case where the first region 21 and the second region 22 are provided in the conductive layer 20 . The concentration of the boron EL 2 in the second region 22 may be 85 atm % or more.

The concentration of the boron EL 2 is high in the material including the first metal EL 1 and the boron EL 2 (the material of the conductive layer 20 ). In other words, the concentration of a light element is high in the conductive layer 20 . Therefore, a low damping constant is obtained. The thickness of the magnetic dead layer can be thin. For example, the write operation is stable. A magnetic memory device can be provided in which stable operations are possible.

The first metal EL 1 (e.g., a rare earth or the like) oxidizes easily. The boron EL 2 oxidizes easily. Therefore, as described below, good insulative properties are obtained for the side surface of the stacked body SB 1 , etc., when patterning the stacked body SB 1 due to at least one of an oxide of the first metal EL 1 or an oxide of the boron EL 2 of the conductive layer 20 .

In another embodiment, the first metal may include at least one selected from the group consisting of Ca, Sr, and Ba. Such an element is, for example, an alkaline earth metal. Even in such a case, the material that includes the first metal (the alkaline earth metal recited above) and the boron EL 2 is a hexaboride. The material that includes the first metal (the alkaline earth metal recited above) and the boron EL 2 has, for example, a CsCl crystal structure.

For example, the conductive layer 20 includes at least one selected from the group consisting of CaB 6 , SrB 6 , and BaB 6 in the case where the first metal (the alkaline earth metal recited above) includes at least one selected from the group consisting of Ca, Sr, and Ba. In one example as recited above, the first metal is, for example, an alkaline earth metal.

The lattice constant of the material including such an element (the first metal (the alkaline earth metal recited above)) and the boron EL 2 is different from the lattice constant of the material included in the second magnetic layer 12 (e.g., CoFe, CoFeB, etc.). The lattice length of the second magnetic layer 12 changes from the lattice constant due to the lattice constant difference. Thereby, for example, anisotropy occurs in the second magnetic layer 12 .

Such a distortion is generated in the second magnetic layer 12 . The distortion is anisotropic distortion. For example, the magnetic characteristics of the second magnetic layer 12 can be controlled. For example, a voltage effect is obtained.

As described above, the conductive layer 20 includes a hexaboride. The concentration of the boron EL 2 in the conductive layer 20 is, for example, 80 atm % or more. The concentration of the boron EL 2 in the conductive layer 20 may be, for example, 85 atm % or more.

The concentration of the boron EL 2 is high in the material (the material of the conductive layer 20 ) including the first metal (the alkaline earth metal recited above) and the boron EL 2 . In other words, the concentration of a light element is high in the conductive layer 20 . Therefore, a low damping constant is obtained. The thickness of the magnetic dead layer can be thin. For example, the write operation is stable. A magnetic memory device can be provided in which stable operations are possible.

The first metal (the alkaline earth metal recited above) oxidizes easily. The boron EL 2 oxidizes easily. Therefore, as described below, good insulative properties are obtained for the side surface of the stacked body SB 1 , etc., when patterning the stacked body SB 1 due to at least one of the oxide of the first metal (the alkaline earth metal recited above) or the oxide of the boron EL 2 of the conductive layer 20 .

Several examples of the magnetic memory device according to the embodiment will now be described.

FIG. 4 is a schematic perspective view illustrating another magnetic memory device according to the first embodiment.

In the magnetic memory device 110 b according to the embodiment as shown in FIG. 4 , the thickness of a portion of the conductive layer 20 is thinner than the other portions. These configurations of the magnetic memory device 110 b are similar to the configurations of the magnetic memory device 110 a.

In the example, the conductive layer 20 further includes a third region 23 and a fourth region 24 in addition to the first region 21 and the second region 22 . The second region 22 is between the third region 23 and the fourth region 24 in the second direction (the X-axis direction). In the example, the thickness along the first direction (the Z-axis direction) of the second region 22 is thicker than the thickness along the first direction of the third region 23 . The thickness along the first direction (the Z-axis direction) of the second region 22 is thicker than the thickness along the first direction of the fourth region 24 .

A large spin Hall effect is obtained in such a magnetic memory device 110 b as well. Stable operations are possible.

For example, the magnetic memory device 110 b is formed by forming, on a film used to form the conductive layer 20 including the first region 21 to the fourth region 24 , a stacked film including a film used to form the second magnetic layer, and by subsequently patterning the stacked film. At this time, the magnetic memory device 110 a or 110 b is formed according to the conditions of the patterning. In other words, the magnetic memory device 110 b is formed in the case where a portion of the film used to form the conductive layer 20 is removed in the patterning processing.

FIG. 5 is a schematic perspective view illustrating another magnetic memory device according to the first embodiment.

As shown in FIG. 5 , the magnetic memory device 111 according to the embodiment also includes the conductive layer 20 , the first magnetic layer 11 , the second magnetic layer 12 , the first nonmagnetic layer 11 n , and the controller 70 . In the magnetic memory device 111 , the configuration of the conductive layer 20 is different from that of the magnetic memory device 110 . Otherwise, the configuration of the magnetic memory device 111 is similar to the configuration of the magnetic memory device 110 .

In the magnetic memory device 111 , the conductive layer 20 further includes the third region 23 and the fourth region 24 in addition to the first region 21 and the second region 22 . The second region 22 is between the third region 23 and the fourth region 24 in the second direction (the X-axis direction). For example, the third region 23 and the fourth region 24 do not include the boron EL 2 . Or, the concentration of the boron EL 2 in the third region 23 and the concentration of the boron EL 2 in the fourth region 24 each are lower than the concentration (the second concentration) of the boron EL 2 in the second region 22 .

In the magnetic memory device 111 , the portion of the conductive layer 20 overlapping the second magnetic layer 12 locally includes the boron EL 2 . In the magnetic memory device 111 , the portion (e.g., the third region 23 and the fourth region 24 ) of the conductive layer 20 not overlapping the second magnetic layer 12 has a composition similar to that of the first region 21 . For example, the resistance of the conductive layer 20 can be low. For example, there is a tendency for the resistivity of the second region 22 to be higher than the resistivities of the first region 21 , the third region 23 , and the fourth region 24 . For example, the resistance of the conductive layer 20 can be set to be low by locally providing a portion including the boron EL 2 .

FIG. 6 is a schematic perspective view illustrating another magnetic memory device according to the first embodiment.

As shown in FIG. 6 , the magnetic memory device 120 according to the embodiment also includes the conductive layer 20 , the first magnetic layer 11 , the second magnetic layer 12 , the first nonmagnetic layer 11 n , and the controller 70 . In the magnetic memory device 120 , the direction of the first magnetization 11 M of the first magnetic layer 11 is different from that of the magnetic memory device 110 . Otherwise, the configuration of the magnetic memory device 120 is similar to the configuration of the magnetic memory device 110 .

In the magnetic memory device 120 , the first magnetization 11 M of the first magnetic layer 11 is aligned with the second direction (e.g., the X-axis direction). For example, the second magnetization 12 M of the second magnetic layer 12 is substantially aligned with the second direction.

In the magnetic memory device 120 , for example, a direct switching mode operation is performed. The speed of the magnetization reversal in the direct switching mode is higher than the speed of the magnetization reversal in a precessional switching mode. The magnetization reversal does not follow the precession in the direct switching mode. Therefore, the magnetization reversal rate is independent of the damping constant α. In the magnetic memory device 120 , a high-speed magnetization reversal is obtained.

In the magnetic memory device 120 , for example, the length in one direction (the length in the major-axis direction) of the first magnetic layer 11 is longer than the length in another one direction (the minor-axis direction length) of the first magnetic layer 11 . For example, the length along the second direction (e.g., the X-axis direction) (the length in the major-axis direction) of the first magnetic layer 11 is longer than the length along the third direction (e.g., the Y-axis direction) (the minor-axis direction length) of the first magnetic layer 11 . For example, the first magnetization 11 M of the first magnetic layer 11 is easily aligned with the second direction due to the shape anisotropy.

In the magnetic memory device 120 , for example, the major-axis direction of the first magnetic layer 11 is aligned with the second direction. The major-axis direction of the first magnetic layer 11 may be tilted with respect to the second direction. For example, the angle (the absolute value of the angle) between the major-axis direction of the first magnetic layer 11 and the second direction (a direction corresponding to the direction of the current flowing through the conductive layer 20 ) is, for example, not less than 0 degrees but less than 30 degrees. By such a configuration, for example, a high writing speed is obtained.

FIG. 7 is a schematic perspective view illustrating another magnetic memory device according to the first embodiment.

As shown in FIG. 7 , the magnetic memory device 121 according to the embodiment also includes the conductive layer 20 , the first magnetic layer 11 , the second magnetic layer 12 , the first nonmagnetic layer 11 n , and the controller 70 . In the magnetic memory device 121 , the conductive layer 20 includes the first region 21 and the second region 22 described above. Otherwise, the configuration of the magnetic memory device 121 is similar to the configuration of the magnetic memory device 120 .

Examples of the materials included in the various layers of the embodiment will now be described.

In the first embodiment, the second magnetic layer 12 includes, for example, at least one first element selected from the group consisting of Co, Fe, and Ni. The second magnetic layer 12 may further include boron (B). The second magnetic layer 12 may further include at least one second element selected from the group consisting of C, N, O, Si, and P. In the second magnetic layer 12 , the concentrations of boron (the B) and the second element are, for example, 30 atm % or less. Thereby, for example, at least one of the lattice constant, the crystallinity, the magnetic properties, the mechanical properties, or the chemical properties can be controlled. By using such a material, for example, a high spin polarization ratio is obtained. For example, the second magnetic layer 12 includes at least one selected from the group consisting of Co, Fe, CoFe, CoFeB, FeB, CoB, CoFeSi, CoFeP, FeNi, FeNiB, FeNiSi, and FeNiP. The second magnetic layer 12 may include a stacked film including multiple films having different compositions. The second magnetic layer 12 includes, for example, CoFeB/CoFe or CoFeB/FeNiB. The second magnetic layer 12 may include, for example, a stacked film including multiple CoFeB films having mutually-different compositions. The second magnetic layer 12 may include, for example, a stacked film including multiple CoFe films having mutually-different compositions.

The second magnetic layer 12 may include, for example, a magnetic layer including a Co-based Heusler alloy. The Co-based Heusler alloy is notated as Co 2 YZ. The second magnetic layer 12 includes at least one selected from the group consisting of Co 2 FeAl, Co 2 MnSi, Co 2 MnGe, Co 2 Mn(Si, Ge), and Co 2 Mn(Ga, Ge).

The second magnetic layer 12 may have, for example, a stacked structure. The stacked structure is, for example, a SAF structure. In the SAF structure, for example, the effects of the stray magnetic field on the adjacent bits can be reduced.

The stacked structure includes, for example, CoFe(B)/(Ta, W, Mo, Cu, Cr)/CoFe(B), a Co-based Heusler alloy/(Ta, W, Mo, Cu, Cr)/CoFe(B), etc. The notation “(Ta, W, Mo, Cu, Cr)” means the inclusion of at least one selected from the group consisting of Ta, W, Mo, Cu, and Cr. The SAF structure includes, for example, at least one selected from the group consisting of CoFe(B)/(Ru, Rh, Ir)/CoFe(B) and a Co-based Heusler alloy/(Ru, Rh, Ir)/CoFe(B). The notation “(Ru, Rh, Ir)” means the inclusion of at least one selected from the group consisting of Ru, Rh, and Ir. The notation “(B)” means that B is included, or B is substantially not included.

The second magnetic layer 12 may include a stacked body. The stacked body includes, for example, at least one selected from the group consisting of a Co/Pt artificial lattice, a Co/Pd artificial lattice, a Co/Ru artificial lattice, a Co/Ir artificial lattice, and a Co/Au artificial lattice. In these artificial lattices, the addition of elements and the ratio of the thicknesses of the magnetic films and the nonmagnetic film are adjusted. Thereby, for example, the perpendicular magnetic anisotropy and the saturation magnetization are adjusted.

The first magnetic layer 11 has at least one of a coercivity that is larger than the coercivity of the second magnetic layer 12 , a magnetic anisotropy energy that is larger than the magnetic anisotropy energy of the second magnetic layer 12 , or a damping constant that is larger than the damping constant of the second magnetic layer 12 . Thereby, the change of the electrical resistance of the magnetic memory device is obtained stably. The first magnetic layer 11 may include a stacked film including a first layer and a second layer. The first layer includes, for example, Mn and at least one element selected from the group consisting of Ir, Pt, Fe, and Rh. The second layer includes at least one element selected from the group consisting of Co, Fe, and Ni. The first magnetic layer 11 includes, for example, at least one selected from the group consisting of IrMn/CoFe, PtMn/CoFe, FeMn/CoFe, and RhMn/CoFe. For example, a stable magnetization direction is obtained. The first magnetic layer 11 may include a first layer, a second layer, a third layer, and a fourth layer. The fourth layer is provided between the third layer and the second layer. For example, the third layer contacts the first nonmagnetic layer 11 n and has, for example, a high spin polarization ratio. The first magnetic layer 11 includes, for example, at least one selected from the group consisting of IrMn/CoFe/Ru/CoFeB, PtMn/CoFe/Ru/CoFeB, FeMn/CoFe/Ru/CoFeB, and RhMn/CoFe/Ru/CoFeB. Thereby, for example, a stable magnetization direction is obtained. For example, the change of the electrical resistance of the magnetic memory device is obtained stably.

The first nonmagnetic layer 11 n includes, for example, at least one selected from the group consisting of MgO, MgAlO, and AlO. The first nonmagnetic layer 11 n may include a stacked film including multiple films including these materials. The first nonmagnetic layer 11 n may further include other nonmagnetic metals.

Second Embodiment

FIG. 8 is a schematic perspective view illustrating a magnetic memory device according to the second embodiment.

As shown in FIG. 8 , the magnetic memory device 130 according to the second embodiment also includes the conductive layer 20 , the first magnetic layer 11 , the second magnetic layer 12 , the first nonmagnetic layer 11 n , and the controller 70 . In the magnetic memory device 130 , the direction of the first magnetization 11 M of the first magnetic layer 11 is different from that of the magnetic memory device 110 . Otherwise, the configuration of the magnetic memory device 130 is similar to the configuration of the magnetic memory device 110 .

In the magnetic memory device 130 , the first magnetization 11 M of the first magnetic layer 11 is aligned with the first direction (e.g., the Z-axis direction). For example, the second magnetization 12 M of the second magnetic layer 12 is substantially aligned with the first direction.

For example, the easy magnetization axis of the second magnetic layer 12 is aligned with the first direction (the Z-axis direction). For example, the absolute value of the angle between the Z-axis direction and the easy magnetization axis of the second magnetic layer 12 is 45 degrees or less.

A large spin Hall effect is obtained in the magnetic memory device 130 as well. Stable operations are possible.

For example, a direct switching mode operation is performed in the magnetic memory device 130 . In the magnetic memory device 130 , a high-speed magnetization reversal is obtained.

In the magnetic memory device 130 , for example, the length along the second direction of the first magnetic layer 11 may be substantially the same as the length along the third direction of the first magnetic layer 11 . In the magnetic memory device 130 , a fine first stacked body SB 1 (e.g., a MTJ element) is obtained easily. For example, a high storage density is obtained.

FIG. 9 is a schematic perspective view illustrating another magnetic memory device according to the second embodiment.

As shown in FIG. 9 , the magnetic memory device 131 according to the embodiment also includes the conductive layer 20 , the first magnetic layer 11 , the second magnetic layer 12 , the first nonmagnetic layer 11 n , and the controller 70 . In the magnetic memory device 131 , the conductive layer 20 includes the first region 21 and the second region 22 described above. Otherwise, the configuration of the magnetic memory device 131 is similar to the configuration of the magnetic memory device 130 .

In the magnetic memory device 131 , the lattice of the conductive layer 20 (the first region 21 ) is stable because the first region 21 and the second region 22 recited above are provided. Thereby, the distortion of the lattice can be formed effectively in the second magnetic layer 12 . By locally providing the second region 22 including B, a stable lattice can be maintained in the entire conductive layer 20 . Also, the scattering efficiency of the electrons increases due to the local second region 22 including B. Thereby, a large spin Hall effect is obtained. In the magnetic memory device 131 as well, a large spin Hall effect is obtained. Stable operations are possible.

Examples of the materials of the second embodiment will now be described.

The second magnetic layer 12 may include a perpendicular magnetic film. An example of the case where the second magnetic layer 12 is a perpendicular magnetic film is as follows. The second magnetic layer 12 includes Mn and at least one element. The at least one element includes at least one selected from the group consisting of Al, Ge, and Ga. The second magnetic layer 12 includes, for example, at least one selected from the group consisting of MnGa, MnAl, MnGe, and MnAlGe. For example, the second magnetic layer 12 includes Mn, Ga, and at least one element. The at least one element includes at least one selected from the group consisting of Al, Ge, Ir, Cr, Co, Pt, Ru, Pd, Rh, Ni, Fe, Re, Au, Cu, B, C, P, Gd, Tb, and Dy. The second magnetic layer 12 includes, for example, at least one selected from the group consisting of MnGaAl, MnGaGe, MnGaIr, MnGaCr, MnGaCo, MnGaPt, MnGaRu, MnGaPd, MnGaRh, MnGaNi, MnGaFe, MnGaRe, MnGaAu, MnGaCu, MnGaB, MnGaC, MnGaP, MnGaGd, MnGaTb, and MnGaDy.

In the case where the second magnetic layer 12 includes a perpendicular magnetic film, the second magnetic layer 12 may include, for example, an alloy. The alloy includes one element and another one element. The one element includes, for example, at least one selected from the group consisting of Fe, Co, and Ni. The other one element includes, for example, at least one selected from the group consisting of Ru, Rh, Pd, Ag, Ir, Pt, and Au. The alloy recited above may include, for example, at least one selected from the group consisting of FeRh, FePt, FePd, CoPt, and CoPd. These alloys are, for example, ferromagnetic alloys.

The first magnetic layer 11 may include, for example, an alloy in the case where the first magnetic layer 11 includes a perpendicular magnetic film. The crystal of at least a portion of the alloy has, for example, a (111) face-centered cubic structure (FCC) orientation. Or, the crystal of at least a portion of the alloy has a (0001) hexagonal close-packed structure (HCP) orientation. The alloy that is included in the first magnetic layer 11 may form, for example, an artificial lattice. For example, the alloy recited above that has the (111) FCC or (0001) HCP crystal orientation includes, for example, one element and another one element. The one element includes at least one selected from the group consisting of Fe, Co, Ni, and Cu. The other one element includes at least one selected from the group consisting of Pt, Pd, Rh, and Au. The alloy that is included in the first magnetic layer 11 is, for example, a ferromagnetic alloy. The ferromagnetic alloy includes, for example, at least one selected from the group consisting of CoPd, CoPt, NiCo, and NiPt.

The alloy recited above that is included in the first magnetic layer 11 and may form the artificial lattice includes, for example, a first layer and a second layer that are stacked alternately. The first layer includes, for example, an alloy (a ferromagnetic film) including one element selected from the group consisting of Fe, Co, and Ni. The second layer includes, for example, an alloy (a nonmagnetic film) including one element selected from the group consisting of Cr, Pt, Pd, Ir, Rh, Ru, Os, Re, Au, and Cu. The first magnetic layer 11 includes, for example, at least one selected from the group consisting of a Co/Pt artificial lattice, a Co/Pd artificial lattice, a CoCr/Pt artificial lattice, a Co/Ru artificial lattice, a Co/Ir artificial lattice, a Co/Os artificial lattice, a Co/Au artificial lattice, and a Ni/Cu artificial lattice. In these artificial lattices, at least one of the addition of an element to the ferromagnetic film or the ratio of the thicknesses of the ferromagnetic films and the nonmagnetic film is adjusted. At least one of the perpendicular magnetic anisotropy or the saturation magnetization can be adjusted.

The first magnetic layer 11 may include an alloy. The alloy includes one element and another one element. The one element includes at least one selected from the group consisting of Fe, Co, and Ni. The one element is, for example, a transition metal. The other one element includes, for example, at least one selected from the group consisting of Tb, Dy, and Gd. The other one element is, for example, a rare-earth metal. The first magnetic layer 11 includes, for example, at least one selected from the group consisting of TbFe, TbCo, TbFeCo, DyFeCo, GdFeCo, DyTbFeCo, and GdTbCo. The first magnetic layer 11 may include a stacked body. The stacked body includes multiple layers. Each of the multiple layers includes the alloy recited above. Multiple types of layers may be stacked alternately in the stacked body. The first magnetic layer 11 may include, for example, at least one stacked body selected from the group consisting of TbFe/Co, TbCo/Fe, TbFeCo/CoFe, DyFe/Co, DyCo/Fe, and DyFeCo/CoFe. For example, at least one of the thickness or the composition is adjusted for these alloys. For example, at least one of the perpendicular magnetic anisotropy or the saturation magnetization is adjusted.

The first magnetic layer 11 may include an alloy. The alloy includes one element and another one element. The one element includes at least one selected from the group consisting of Fe, Co, Ni, and Cu. The other one element includes at least one selected from the group consisting of Pt, Pd, Rh, and Au. The first magnetic layer 11 includes, for example, a ferromagnetic alloy. The ferromagnetic alloy includes at least one selected from the group consisting of FeRh, FePt, FePd, CoPt, and CoPd.

The material of the first nonmagnetic layer 11 n of the second embodiment is similar to the material of the first nonmagnetic layer 11 n of the first embodiment.

Third Embodiment

FIG. 10 is a schematic cross section illustrating a magnetic memory device according to a third embodiment.

As shown in FIG. 10 , the magnetic memory device 141 according to the embodiment includes a third magnetic layer 13 , a fourth magnetic layer 14 , and a second nonmagnetic layer 12 n in addition to the conductive layer 20 , the first magnetic layer 11 , the second magnetic layer 12 , and the first nonmagnetic layer 11 n . The magnetic memory device 141 also includes the controller 70 (referring to FIG. 1A ). The controller 70 is not illustrated in FIG. 10 .

The first magnetic layer 11 , the second magnetic layer 12 , and the first nonmagnetic layer 11 n are included in the first stacked body SB 1 . The third magnetic layer 13 , the fourth magnetic layer 14 , and the second nonmagnetic layer 12 n are included in a second stacked body SB 2 . In the example, the first stacked body SB 1 further includes a first electrode layer E 1 . The second stacked body SB 2 further includes a second electrode layer E 2 .

The conductive layer 20 further includes a fourth portion 20 d and a fifth portion 20 e in addition to the first to third portions 20 a to 20 c . The third portion 20 c is positioned between the first portion 20 a and the second portion 20 b in the second direction (the X-axis direction). The fourth portion 20 d is provided between the third portion 20 c and the second portion 20 b in the second direction. The fifth portion 20 e is provided between the fourth portion 20 d and the second portion 20 b in the second direction.

The first magnetic layer 11 is provided between the first electrode layer E 1 and the third portion 20 c in the first direction (the Z-axis direction). The second magnetic layer 12 is provided between the first magnetic layer 11 and the third portion 20 c . The first nonmagnetic layer 11 n is provided between the first magnetic layer 11 and the second magnetic layer 12 .

The third magnetic layer 13 is provided between the second electrode layer E 2 and the fifth portion 20 e in the first direction (the Z-axis direction). The fourth magnetic layer 14 is provided between the third magnetic layer 13 and the fifth portion 20 e . The second nonmagnetic layer 12 n is provided between the third magnetic layer 13 and the fourth magnetic layer 14 .

The first stacked body SB 1 and the second stacked body SB 2 each are memory cells MC.

As described above, the conductive layer 20 includes the first region 21 and the second region 22 . The second region 22 is provided between the first region 21 and the second magnetic layer 12 . For example, the second region 22 physically contacts the second magnetic layer 12 . The second region 22 includes the first metal EL 1 and the boron EL 2 . The conductive layer 20 further includes another first region 21 A and another second region 22 A. The other second region 22 A is provided between the other first region 21 A and the fourth magnetic layer 14 . For example, the other second region 22 A physically contacts the fourth magnetic layer 14 . The other second region 22 A includes the first metal EL 1 and the boron EL 2 .

A first insulating region 51 is further provided in the magnetic memory device 141 . For example, at least a portion of the first insulating region 51 is positioned between the second region 22 and the other second region 22 A in the second direction (the X-axis direction). The first insulating region 51 includes, for example, an element included in the second region 22 and the other second region 22 A. The first insulating region 51 includes, for example, at least one of an oxide including the element included in the second region 22 and the other second region 22 A or a nitride including the element. For example, a material that has insulative properties is formed from a film including the materials used to form the second region 22 and the other second region 22 A. The first insulating region 51 includes this material. Good insulative properties are obtained. Stable characteristics are obtained. The first insulating region 51 does not overlap the first magnetic layer 11 in the first direction (the Z-axis direction). The first insulating region 51 does not overlap the second magnetic layer 12 in the first direction (the Z-axis direction). The first insulating region 51 includes the first metal EL 1 and at least one selected from the group consisting of oxygen and nitrogen. The first insulating region 51 may further include the boron EL 2 .

For example, at least a portion of the first insulating region 51 may be formed by a reaction (e.g., at least one of oxidization or nitridation) of at least a portion of the film used to form the second region 22 and the other second region 22 A. At least a portion of the first insulating region 51 may include an unreacted portion of the film used to form the second region 22 and the other second region 22 A.

FIG. 11 is a schematic cross section illustrating another magnetic memory device according to the third embodiment.

As shown in FIG. 11 , a second insulating region 52 is further provided in the magnetic memory device 142 according to the embodiment. Otherwise, the configuration of the magnetic memory device 142 is the same as the configuration of the magnetic memory device 141 .

For example, at least a portion of the second insulating region 52 is positioned between the second magnetic layer 12 and the fourth magnetic layer 14 in the second direction (the X-axis direction). The second insulating region 52 includes, for example, an element included in the second magnetic layer 12 and the fourth magnetic layer 14 . The second insulating region 52 includes, for example, at least one of an oxide including the element included in the second magnetic layer 12 and the fourth magnetic layer 14 or a nitride including the element. For example, a material that has insulative properties is formed from a film including the materials used to form the second magnetic layer 12 and the fourth magnetic layer 14 . The second insulating region 52 includes this material. Good insulative properties are obtained. Stable characteristics are obtained. The direction from the second magnetic layer 12 toward the second insulating region 52 is aligned with the second direction (the X-axis direction).

For example, at least a portion of the second insulating region 52 may be formed by a reaction (e.g., at least one of oxidization or nitridation) of at least a portion of the film used to form the second magnetic layer 12 and the fourth magnetic layer 14 . At least a portion of the second insulating region 52 may include an unreacted portion of the film used to form the second magnetic layer 12 and the fourth magnetic layer 14 .

FIG. 12 is a schematic cross section illustrating another magnetic memory device according to the third embodiment.

As shown in FIG. 12 , a third insulating region 53 is further provided in the magnetic memory device 143 according to the embodiment. Otherwise, the configuration of the magnetic memory device 143 is the same as the configuration of the magnetic memory device 142 .

For example, at least a portion of the third insulating region 53 is positioned between the first nonmagnetic layer 11 n and the second nonmagnetic layer 12 n in the second direction (the X-axis direction). The third insulating region 53 includes, for example, an element included in the first nonmagnetic layer 11 n and the second nonmagnetic layer 12 n . The third insulating region 53 includes, for example, at least one of an oxide including the element included in the first nonmagnetic layer 11 n and the second nonmagnetic layer 12 n or a nitride including the element. For example, a material that has insulative properties is formed from the film including the materials used to form the first nonmagnetic layer 11 n and the second nonmagnetic layer 12 n . The third insulating region 53 includes this material. Good insulative properties are obtained. Stable characteristics are obtained. The direction from the first nonmagnetic layer 11 n toward the third insulating region 53 is aligned with the second direction (the X-axis direction).

For example, at least a portion of the third insulating region 53 may be formed by a reaction (e.g., at least one of oxidization or nitridation) of at least a portion of the film used to form the first nonmagnetic layer 11 n and the second nonmagnetic layer 12 n . At least a portion of the third insulating region 53 may include an unreacted portion of the film used to form the first nonmagnetic layer 11 n and the second nonmagnetic layer 12 n.

At least one of the first to third insulating regions 51 to 53 is applicable to any magnetic memory device according to the first and second embodiments.

Fourth Embodiment

FIG. 13 is a schematic perspective view illustrating a magnetic memory device according to a fourth embodiment.

As shown in FIG. 13 , multiple stacked bodies (the first stacked body SB 1 , the second stacked body SB 2 , a stacked body SBx, etc.) are provided in the magnetic memory device 210 according to the embodiment. Multiple switches (the switch Sw 1 , a switch Sw 2 , a switch Swx, etc.) also are provided. Otherwise, the configuration of the magnetic memory device 210 is similar to that of the magnetic memory device 110 .

The conductive layer 20 further includes the fourth portion 20 d and the fifth portion 20 e in addition to the first to third portions 20 a to 20 c . As described above, the third portion 20 c is positioned between the first portion 20 a and the second portion 20 b in the second direction (the X-axis direction). The fourth portion 20 d is provided between the third portion 20 c and the second portion 20 b in the second direction. The fifth portion 20 e is provided between the fourth portion 20 d and the second portion 20 b in the second direction.

The multiple stacked bodies are arranged along the conductive layer 20 . The first stacked body SB 1 overlaps the third portion 20 c in the first direction (the Z-axis direction). The second stacked body SB 2 overlaps the fifth portion 20 e in the first direction. The direction from the first stacked body SB 1 toward the second stacked body SB 2 is aligned with the second direction.

For example, the second stacked body SB 2 includes the third magnetic layer 13 , the fourth magnetic layer 14 , and the second nonmagnetic layer 12 n . The third magnetic layer 13 is separated from a portion (the fifth portion 20 e ) of the conductive layer 20 in the first direction (the Z-axis direction). The fourth magnetic layer 14 is provided between the third magnetic layer 13 and the portion (the fifth portion 20 e ) of the conductive layer 20 . The second nonmagnetic layer 12 n is provided between the third magnetic layer 13 and the fourth magnetic layer 14 .

For example, the third magnetic layer 13 is separated from the first magnetic layer 11 in the second direction (e.g., the X-axis direction). The fourth magnetic layer 14 is separated from the second magnetic layer 12 in the second direction. The second nonmagnetic layer 12 n is separated from the first nonmagnetic layer 11 n in the second direction.

For example, the stacked body SBx includes a magnetic layer 11 x , a magnetic layer 12 x , and a nonmagnetic layer 11 nx . The magnetic layer 11 x is separated from another portion of the conductive layer 20 in the first direction (the Z-axis direction). The magnetic layer 12 x is provided between the magnetic layer 11 x and the other portion of the conductive layer 20 . The nonmagnetic layer 11 nx is provided between the magnetic layer 11 x and the magnetic layer 12 x.

For example, the material and the configuration of the third magnetic layer 13 are the same as the material and the configuration of the first magnetic layer 11 . For example, the material and the configuration of the fourth magnetic layer 14 are the same as the material and the configuration of the second magnetic layer 12 . For example, the material and the configuration of the second nonmagnetic layer 12 n are the same as the material and the configuration of the first nonmagnetic layer 11 n.

The multiple stacked bodies function as multiple memory cells MC.

The switch Sw 1 is electrically connected to the first magnetic layer 11 . The switch Sw 2 is electrically connected to the third magnetic layer 13 . The switch Swx is electrically connected to the magnetic layer 11 x . These switches are electrically connected to the control circuit 75 of the controller 70 . Any of the multiple stacked bodies are selected by these switches.

FIG. 14 is a schematic perspective view illustrating another magnetic memory device according to the fourth embodiment.

As shown in FIG. 14 , multiple stacked bodies and multiple switches are provided in the magnetic memory device 211 according to the embodiment as well. Otherwise, the configuration of the magnetic memory device 211 is similar to the magnetic memory device 210 .

The first region 21 and the second region 22 are provided in the magnetic memory device 211 . The second region 22 is provided also between the fourth magnetic layer 14 and the first region 21 . The second region 22 of the conductive layer 20 is provided also between the magnetic layer 12 x and the first region 21 . In the example of the magnetic memory device 211 , the second region 22 extends along the second direction (e.g., the X-axis direction). The second region 22 is provided also in a region corresponding to the region between the multiple stacked bodies.

Fifth Embodiment

FIG. 15A to FIG. 15C are schematic perspective views illustrating a magnetic memory device according to a fifth embodiment.

As shown in FIG. 15A , multiple stacked bodies (the first stacked body SB 1 and the second stacked body SB 2 ) are provided in the magnetic memory device 220 according to the embodiment as well. In the magnetic memory device 220 , the current that flows in the first stacked body SB 1 and the current that flows in the second stacked body SB 2 are different from each other.

The first stacked body SB 1 overlaps the third portion 20 c in the first direction (the Z-axis direction). The second stacked body SB 2 overlaps the fifth portion 20 e in the first direction. The fourth portion 20 d of the conductive layer 20 corresponds to a portion between the first stacked body SB 1 and the second stacked body SB 2 .

For example, a first terminal T 1 is electrically connected to the first portion 20 a of the conductive layer 20 . A second terminal T 2 is electrically connected to the second portion 20 b . A third terminal T 3 is electrically connected to the fourth portion 20 d . A fourth terminal T 4 is electrically connected to the first magnetic layer 11 . A fifth terminal T 5 is electrically connected to the third magnetic layer 13 .

In one operation OP 1 as shown in FIG. 15A , the first current Iw 1 flows from the first terminal T 1 toward the third terminal T 3 ; and a third current Iw 3 flows from the second terminal T 2 toward the third terminal T 3 . The orientation of the current (the first current Iw 1 ) at the position of the first stacked body SB 1 is the reverse of the orientation of the current (the third current Iw 3 ) at the position of the second stacked body SB 2 . In such an operation OP 1 , the orientation of the spin Hall torque acting on the second magnetic layer 12 of the first stacked body SB 1 is the reverse of the orientation of the spin Hall torque acting on the fourth magnetic layer 14 of the second stacked body SB 2 .

In another operation OP 2 shown in FIG. 15B , the second current Iw 2 flows from the third terminal T 3 toward the first terminal T 1 ; and a fourth current Iw 4 flows from the third terminal T 3 toward the second terminal T 2 . The orientation of the current (the second current Iw 2 ) at the position of the first stacked body SB 1 is the reverse of the orientation of the current (the fourth current Iw 4 ) at the position of the second stacked body SB 2 . In such an operation OP 2 , the orientation of the spin Hall torque acting on the second magnetic layer 12 of the first stacked body SB 1 is the reverse of the orientation of the spin Hall torque acting on the fourth magnetic layer 14 of the second stacked body SB 2 .

As shown in FIG. 15A and FIG. 15B , the orientation of a fourth magnetization 14 M of the fourth magnetic layer 14 is the reverse of the orientation of the second magnetization 12 M of the second magnetic layer 12 . On the other hand, the orientation of a third magnetization 13 M of the third magnetic layer 13 is the same as the orientation of the first magnetization 11 M of the first magnetic layer 11 . Thus, magnetization information that has reverse orientations between the first stacked body SB 1 and the second stacked body SB 2 is stored. For example, the information (the data) in the case of the operation OP 1 corresponds to “1.” For example, the information (the data) in the case of the operation OP 2 corresponds to “0.” By such operations, for example, the reading can be faster as described below.

In the operation OP 1 and the operation OP 2 , the second magnetization 12 M of the second magnetic layer 12 and the spin current of the electrons (the polarized electrons) flowing through the conductive layer 20 have an interaction. The orientation of the second magnetization 12 M and the orientation of the spin of the polarized electrons have a parallel or an antiparallel relationship. The second magnetization 12 M of the second magnetic layer 12 precesses and reverses. In the operation OP 1 and the operation OP 2 , the orientation of the fourth magnetization 14 M of the fourth magnetic layer 14 and the orientation of the spin of the polarized electrons have a parallel or an antiparallel relationship. The fourth magnetization 14 M of the fourth magnetic layer 14 precesses and reverses.

FIG. 15C illustrates a read operation of the magnetic memory device 220 .

In the read operation OP 3 , the potential of the fourth terminal T 4 is set to a fourth potential V 4 . The potential of the fifth terminal T 5 is set to a fifth potential V 5 . The fourth potential V 4 is, for example, a ground potential. The potential difference between the fourth potential V 4 and the fifth potential V 5 is taken as ΔV. Two electrical resistances of each of the multiple stacked bodies are taken as a high resistance Rh and a low resistance RI. The high resistance Rh is higher than the low resistance RI. For example, the resistance corresponds to the high resistance Rh when the first magnetization 11 M and the second magnetization 12 M are antiparallel. For example, the resistance corresponds to the low resistance RI when the first magnetization 11 M and the second magnetization 12 M are parallel. For example, the resistance corresponds to the high resistance Rh when the third magnetization 13 M and the fourth magnetization 14 M are antiparallel. For example, the resistance corresponds to the low resistance RI when the third magnetization 13 M and the fourth magnetization 14 M are parallel.

For example, in the operation OP 1 (the “1” state) illustrated in FIG. 15A , a potential Vr 1 of the third terminal T 3 is represented by Formula (1).

Vr 1=( RI /( RI+Rh ))×Δ V   (1)

On the other hand, a potential Vr 2 of the third terminal T 3 in the state of the operation OP 2 (the “0” state) illustrated in FIG. 15B is represented by Formula (2).

Vr 2=(( Rh /( RI+Rh ))×Δ V   (2)

Accordingly, a potential change ΔVr between the “1” state and the “0” state is represented by Formula (3).

Δ Vr=Vr 2− Vr 1=(( Rh−RI )/( RI+Rh ))× ΔV   (3)

The potential change ΔVr is obtained by measuring the potential of the third terminal T 3 .

For example, the consumed energy when reading in the read operation OP 3 recited above can be reduced compared to the case where a constant current is supplied to the stacked body (the magnetoresistive element) and the voltage (the potential difference) is measured between the two magnetic layers of the magnetoresistive element. In the read operation OP 3 recited above, for example, high-speed reading can be performed.

In the operation OP 1 and the operation OP 2 recited above, the perpendicular magnetic anisotropies of the second magnetic layer 12 and the fourth magnetic layer 14 can be controlled by using the fourth terminal T 4 and the fifth terminal T 5 . Thereby, the write current can be reduced. For example, the write current can be about ½ of the write current of the case where the writing is performed without using the fourth terminal T 4 and the fifth terminal T 5 . For example, the write charge can be reduced. The relationship between the increase or decrease of the perpendicular magnetic anisotropy and the polarity of the voltage applied to the fourth terminal T 4 and the fifth terminal T 5 is dependent on the materials of the magnetic layers and the conductive layer 20 .

FIG. 16A to FIG. 16C are schematic perspective views illustrating another magnetic memory device according to the fifth embodiment.

As shown in FIG. 16A to FIG. 16C , the first region 21 and the second region 22 are provided in the magnetic memory device 221 according to the embodiment. Otherwise, the configuration of the magnetic memory device 221 is similar to that of the magnetic memory device 220 .

In FIG. 15C recited above, the first terminal T 1 and the second terminal T 2 may be set to the same potential; the fourth terminal T 4 and the fifth terminal T 5 may be connected to the input terminals of a sense amplifier; and the potential difference between the fourth terminal T 4 and the fifth terminal T 5 may be read by the sense amplifier. A voltage may be applied to one of the first terminal T 1 or the second terminal T 2 ; and the other of the first terminal T 1 or the second terminal T 2 may be floating. Or, the current difference between the fourth terminal T 4 and the fifth terminal T 5 may be read by causing the same current to flow in the first terminal T 1 and the second terminal T 2 . The first terminal T 1 and the second terminal T 2 may be set to the same potential; the fourth terminal T 4 and the fifth terminal T 5 may be connected to the input terminals of a sense amplifier; and the potential difference between the fourth terminal T 4 and the fifth terminal T 5 may be read by the sense amplifier. The fourth terminal T 4 and the fifth terminal T 5 may be set to the same potential; the first terminal T 1 and the second terminal T 2 may be connected to the input terminals of a sense amplifier; and the potential difference between the first terminal T 1 and the second terminal T 2 may be read by the sense amplifier.

Sixth Embodiment

FIG. 17 is a schematic view showing a magnetic memory device according to a sixth embodiment.

As shown in FIG. 17 , a memory cell array MCA, multiple first interconnects (e.g., word lines WL 1 , WL 2 , etc.), multiple second interconnects (e.g., bit lines BL 1 , BL 2 , BL 3 , etc.), and the controller 70 are provided in the magnetic memory device 310 according to the embodiment. The multiple first interconnects extend in one direction. The multiple second interconnects extend in another one direction. The controller 70 includes a word line selection circuit 70 WS, a first bit line selection circuit 70 BSa, a second bit line selection circuit 70 BSb, a first write circuit 70 Wa, a second write circuit 70 Wb, a first read circuit 70 Ra, and a second read circuit 70 Rb. The multiple memory cells MC are arranged in an array configuration in the memory cell array MCA.

For example, the switch Sw 1 and the switch SwS 1 are provided to correspond to one of the multiple memory cells MC. These switches are considered to be included in the one of the multiple memory cells. These switches may be considered to be included in the controller 70 . These switches are, for example, transistors. The one of the multiple memory cells MC includes, for example, a stacked body (e.g., the first stacked body SB 1 ).

As described in reference to FIG. 10 to FIG. 16C , multiple stacked bodies (the first stacked body SB 1 , the second stacked body SB 2 , the stacked body SBx, etc.) may be provided for one conductive layer 20 . Multiple switches (the switch Sw 1 , the switch Sw 2 , the switch Swx, etc.) may be provided respectively for the multiple stacked bodies. In FIG. 17 , one stacked body (the stacked body SB 1 or the like) and one switch (the switch Sw 1 or the like) are drawn to correspond to one conductive layer 20 for easier viewing of the drawing.

As shown in FIG. 17 , one end of the first stacked body SB 1 is connected to the conductive layer 20 . The other end of the first stacked body SB 1 is connected to one of the source or the drain of the switch Sw 1 . The other of the source or the drain of the switch Sw 1 is connected to the bit line BL 1 . The gate of the switch Sw 1 is connected to the word line WL 1 . One end (e.g., the first portion 20 a ) of the conductive layer 20 is connected to one of the source or the drain of the switch SwS 1 . The other end (e.g., the second portion 20 b ) of the conductive layer 20 is connected to the bit line BL 3 . The other of the source or the drain of the switch SwS 1 is connected to the bit line BL 2 . The gate of the switch SwS 1 is connected to the word line WL 2 .

A stacked body SBn, a switch Swn, and a switch SwSn are provided for another one of the multiple memory cells MC.

An example of the write operation of the information to the memory cell MC will now be described.

The switch SwS 1 of one memory cell MC (the selected memory cell) to which the writing is to be performed is set to the ON state. For example, in the ON state, the word line WL 2 that is connected to the gate of one switch SwS 1 is set to a high-level potential. The setting of the potential is performed by the word line selection circuit 70 WS. The switch SwS 1 of another memory cell MC (an unselected memory cell) of the column including the one memory cell MC (the selected memory cell) recited above also is set to the ON state. In one example, the word line WL 1 that is connected to the gate of the switch Sw 1 inside the memory cell MC (the selected memory cell) and the word lines WL 1 and WL 2 that correspond to the other columns are set to a low-level potential.

Although one stacked body and one switch Sw 1 that correspond to one conductive layer 20 are drawn in FIG. 17 , the multiple switches (the switch Sw 1 , the switch Sw 2 , the switch Swx, etc.) and the multiple stacked bodies (the stacked body SB 1 , the second stacked body SB 2 , the stacked body SBx, etc.) that correspond to one conductive layer 20 are provided as described above. In such a case, for example, the switches that are connected respectively to the multiple stacked bodies are set to the ON state. The select voltage is applied to one of the multiple stacked bodies. On the other hand, the unselect voltage is applied to the other stacked bodies. Writing is performed to the one of the multiple stacked bodies recited above; and the writing is not performed to the other stacked bodies. Selective writing of the multiple stacked bodies is performed.

The bit lines BL 2 and BL 3 that are connected to the memory cell MC (the selected cell) to which the writing is to be performed are selected. The selection is performed by the first bit line selection circuit 70 BSa and the second bit line selection circuit 70 BSb. A write current is supplied to the selected bit lines BL 2 and BL 3 . The supply of the write current is performed by the first write circuit 70 Wa and the second write circuit 70 Wb. The write current flows from one of the first bit line selection circuit 70 BSa or the second bit line selection circuit 70 BSb toward the other of the first bit line selection circuit 70 BSa or the second bit line selection circuit 70 BSb. The magnetization direction of the memory layer (the second magnetic layer 12 , etc.) of the MTJ element (the first stacked body SB 1 , etc.) is changeable by the write current. The magnetization direction of the memory layer of the MTJ element is changeable to the reverse direction of that recited above when the write current flows from the other of the first bit line selection circuit 70 BSa or the second bit line selection circuit 70 BSb toward the one of the first bit line selection circuit 70 BSa or the second bit line selection circuit 70 BSb. Thus, the writing is performed.

An example of the read operation of the information from the memory cell MC will now be described.

The word line WL 1 that is connected to the memory cell MC (the selected cell) from which the reading is to be performed is set to the high-level potential. The switch Sw 1 inside the memory cell MC (the selected cell) recited above is set to the ON state. At this time, the switches Sw 1 of the other memory cells MC (the unselected cells) of the column including the memory cell MC (the selected cell) recited above also are set to the ON state. The word line WL 2 that is connected to the gate of the switch SwS 1 inside the memory cell MC (the selected cell) recited above and the word lines WL 1 and WL 2 that correspond to the other columns are set to the low-level potential.

The bit lines BL 1 and BL 3 that are connected to the memory cell MC (the selected cell) from which the reading is to be performed are selected. The selection is performed by the first bit line selection circuit 70 BSa and the second bit line selection circuit 70 BSb. The read current is supplied to the bit line BL 1 and the bit line BL 3 that are selected. The supply of the read current is performed by the first read circuit 70 Ra and the second read circuit 70 Rb. The read current flows from one of the first bit line selection circuit 70 BSa or the second bit line selection circuit 70 BSb toward the other of the first bit line selection circuit 70 BSa or the second bit line selection circuit 70 BSb. For example, the voltage between the selected bit lines BL 1 and BL 3 recited above is sensed by the first read circuit 70 Ra and the second read circuit 70 Rb. For example, the difference between the magnetization of a reference layer (the first magnetic layer 11 ) and the magnetization of a memory layer (the second magnetic layer 12 ) of the MTJ element is sensed. The difference includes the orientation of the magnetization being in a mutually-parallel state (having the same orientation) or a mutually-antiparallel state (having the reverse orientation). Thus, the read operation is performed.

According to the embodiment, a magnetic memory device can be provided in which the write current can be reduced.

In this specification, the notation of “first material/second material” means that the first material is positioned on the second material. For example, a layer of the first material is formed on a layer of the second material.

In this specification, “perpendicular” and “parallel” include not only strictly perpendicular and strictly parallel but also, for example, the fluctuation due to manufacturing processes, etc.; and it is sufficient to be substantially perpendicular and substantially parallel.

Hereinabove, embodiments of the invention are described with reference to examples. However, the invention is not limited to these examples. For example, one skilled in the art may similarly practice the invention by appropriately selecting specific configurations of components included in the magnetic memory device such as the magnetic layer, the nonmagnetic layer, the conductive layer, the controller, etc., from known art; and such practice is within the scope of the invention to the extent that similar effects can be obtained.

Any two or more components of the examples may be combined within the extent of technical feasibility and are within the scope of the invention to the extent that the spirit of the invention is included.

All magnetic memory devices practicable by an appropriate design modification by one skilled in the art based on the magnetic memory devices described above as the embodiments of the invention also are within the scope of the invention to the extent that the spirit of the invention is included.

Various modifications and alterations within the spirit of the invention will be readily apparent to those skilled in the art; and all such modifications and alterations should be seen as being within the scope of the invention.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the invention.