Magnetic memory

Abstract

This invention provides a magnetic memory with a relatively simple structure that can operate with low current consumption even without an external magnetic field. The magnetic memory of this embodiment includes a first electrode and a second and third electrode arranged at a distance in a first direction. A non-magnetic conductive layer electrically connects the second and third electrodes and extends in the first direction. A first magnetic layer is disposed relative to the non-magnetic conductive layer in a second direction intersecting the first direction. The first magnetic layer extends in the first direction and includes a first region and a second region arranged along the first direction. At least a portion of the first region is disposed in the second direction between the first electrode and the non-magnetic conductive layer. A second magnetic layer is disposed between the first region and the first electrode, and its magnetization direction is fixed along the second direction. A non-magnetic insulating layer is disposed between the first and second magnetic layers. When viewed from the second direction, the first electrode is disposed between the second and third electrodes, at least partially overlapping with the second electrode, or at least partially overlapping with the third electrode. The magnetization direction of region 1 is variable along the second direction mentioned above. The magnetization direction of region 2 is fixed along the first direction.

Description

Technical Field

[0001] This embodiment relates to a magnetic memory. Prior Technology

[0002] A magnetic memory (hereinafter also referred to as MRAM (Magnetic Random Access Memory)) has been developed. MTJ (Magnetic Tunnel Junction) elements are used as the memory elements of the MRAM.

[0003] Vertically magnetized SOT (Spin Orbit Torque)-MRAM requires an external magnetic field or a relatively large current to reverse the magnetization direction of the MTJ element.

[0004] Magnetic wall MRAMs cannot function as moving layers of magnetic walls due to damage to tunneling barrier layers, or require complex fixed layer structures to pin the magnetic walls. Summary of the Invention

[0005] This invention provides a magnetic memory with a relatively simple structure that can operate with low current consumption even without an external magnetic field.

[0006] The magnetic memory of this embodiment includes a first electrode and a second electrode and a third electrode arranged at a distance in a first direction. A non-magnetic conductive layer electrically connects the second electrode and the third electrode and extends in the first direction. A first magnetic layer is disposed relative to the non-magnetic conductive layer in a second direction intersecting the first direction. The first magnetic layer extends in the first direction and includes a first region and a second region arranged along the first direction. At least a portion of the first region is disposed in the second direction between the first electrode and the non-magnetic conductive layer. A second magnetic layer is disposed between the first region and the first electrode, and its magnetization direction is fixed along the second direction. A non-magnetic insulating layer is disposed between the first magnetic layer and the second magnetic layer. When viewed from the second direction, the first electrode is disposed between the second electrode and the third electrode, at least partially overlapping with the second electrode, or at least partially overlapping with the third electrode. The magnetization direction of the first region is variable along the second direction. The magnetization direction of the second region is fixed along the first direction. Simple Explanation of the Diagram

[0007] Figure 1 is a perspective view showing an example of the structure of a magnetic memory according to the first embodiment. Figure 2 is a top view showing an example of the configuration of a magnetic memory according to the first embodiment. Figure 3 is an equivalent circuit diagram showing an example of the configuration of the magnetic memory according to the first embodiment. Figure 4 is a cross-sectional view showing an example of the configuration of an MTJ element according to the first embodiment. Figure 5 is a top view showing an example of the configuration of an MTJ element according to the first embodiment. Figure 6 is a diagram showing an example of the operation of the MTJ element according to the first embodiment. Figure 7 is a diagram showing an example of the operation of the MTJ element according to the first embodiment. Figure 8 is a diagram showing an example of the operation of the MTJ element according to the first embodiment. Figure 9 is a diagram showing an example of the operation of the MTJ element according to the first embodiment. Figure 10 is a diagram showing an example of the operation of the MTJ element according to the first embodiment. Figure 11 is a diagram showing an example of the operation of the MTJ element according to the first embodiment. Figure 12 is a cross-sectional view showing an example of the configuration of an MTJ element according to the second embodiment. Figure 13 is a top view showing an example of the configuration of a magnetic memory according to the third embodiment. Figure 14 is a top view showing a configuration example of the MTJ element according to a variation of the above-described embodiment. Figure 15 is a top view showing a configuration example of the MTJ element according to a variation of the above-described embodiment. Figure 16 is a cross-sectional view showing an example of the configuration of an MTJ element according to another variation of the above-described embodiment. Figure 17 is a cross-sectional view showing an example of the configuration of an MTJ element according to another variation of the above-described embodiment. Figure 18 is a top view showing an example of the configuration of an MTJ element according to another variation of the above-described embodiment. Figure 19 is a cross-sectional view showing an example of the configuration of an MTJ element according to another variation of the above-described embodiment. Figure 20 is a cross-sectional view showing an example of the configuration of an MTJ element according to another variation of the above-described embodiment. Implementation

[0008] The embodiments of the present invention will now be described with reference to the drawings. These embodiments do not limit the scope of the invention. The drawings are schematic diagrams or conceptual diagrams. In the specification and drawings, the same elements are labeled with the same symbols.

[0009] In this specification, the mention of "intersecting" relative to a certain direction includes situations where the two are orthogonal relative to that direction. The mention of "tilting" relative to a certain direction means that the two are not orthogonal relative to that direction.

[0010] (First Embodiment) The magnetic memory system of the first embodiment utilizes the spin Hall effect or spin-orbit coupling, specifically a SOT-MRAM that reverses the magnetization direction of the memory layer using spin-orbit torque (SOT). Hereinafter, an example of applying this embodiment to SOT-MRAM will be described. Furthermore, this embodiment can also be applied to magnetic wall MRAM.

[0011] Figure 1 is a perspective view showing a configuration example of the magnetic memory 1 according to the first embodiment. The magnetic memory 1 of this embodiment includes a write word line WWL, a read word line RWL, a write bit line WBL, a read bit line RBL, a magnetoresistive element (hereinafter also referred to as an MTJ element) 10, a write transistor WTr, and a read transistor RTR.

[0012] Furthermore, the Z direction refers to the stacking direction of different types of wiring, such as write bit line WBL, write word line WWL, source line SL, read word line RWL, and read bit line RBL. The Z direction is an example of the second direction. The X direction is any direction within the first plane that intersects (e.g., is orthogonal) the Z direction. The Y direction is a direction within the aforementioned first plane that intersects (e.g., is orthogonal) the X direction. Furthermore, in this embodiment, the +Z direction will be described from the top.

[0013] Write bit line WBL, write word line WWL, source line SL, MTJ element 10, read word line RWL, and read bit line RBL are sequentially stacked. The write bit line WBL, write word line WWL, source line SL, read word line RWL, and read bit line RBL are disposed on layers with different height levels in the Z direction. An interlayer insulating film (not shown) is disposed between the wirings of the write bit line WBL, write word line WWL, source line SL, read word line RWL, and read bit line RBL, and they are electrically isolated from each other.

[0014] A plurality of write bit lines WBL extend in the Y direction and are arranged in the X direction. In this embodiment, the write bit lines WBL are arranged in the Z direction at the bottom layer. When writing data to the memory cell MC, the write bit lines WBL cause the current corresponding to the data to flow in the memory cell MC. For example, they are made of conductive materials such as tungsten.

[0015] A plurality of write character lines WWL extend in the X direction and are arranged in the Y direction. In this embodiment, the write character lines WWL are disposed above the write bit lines WBL in the Z direction. When data is written to the memory cell MC, the write character lines WWL enable the write transistor WTR to be in a conducting state (connected), allowing current to flow in the conductive layer C1 of the MTJ element 10. The write character lines WWL are, for example, made of a conductive material such as tungsten.

[0016] A plurality of source lines SL extend in the Y direction and are arranged in the X direction. In this embodiment, the source lines SL are disposed above the write word line WWL in the Z direction. During write and read operations, the source lines SL receive current from or flow current into the MTJ element 10. The source lines SL are, for example, made of a conductive material such as tungsten. The plurality of source lines SL can be fixed to a common voltage or set to individual different voltages.

[0017] The MTJ element 10, as a magnetoresistive element, is a 3-terminal element. The MTJ element 10 is connected between the source or drain of the write transistor WTr and the source or drain of the read transistor RTr, and between the source line SL and the source or drain of the read transistor RTr. The upper electrode of the MTJ element 10 is connected to the source or drain of the read transistor RTr. The two lower electrodes of the MTJ element 10 are respectively connected to the source or drain of the write transistor WTr and the source line SL.

[0018] A plurality of MTJ elements 10 are disposed in the Z direction above the write bit line WBL, the write word line WWL, and the source line SL (+Z direction). During the write operation, the conductive layer C1 of the MTJ element 10 allows current to flow between the write bit line WBL and the source line SL, or during the read operation, allows current to flow through the MTJ element 10 between the read bit line RBL and the source line SL. The conductive layer C1 is, for example, composed of a stack of a non-magnetic conductive layer (Fig. 4-11) and a magnetic conductive layer (Fig. 4-12). A more detailed description of the configuration of the MTJ element 10 will be given below.

[0019] A plurality of readout word lines RWL extend in the X direction and are arranged in the Y direction. In this embodiment, the readout word lines RWL are disposed above the MTJ element 10 in the Z direction. When data is read from the memory cell MC, the readout transistor RTR is turned on (connected), and current flows between the readout bit line RBL and the source line SL via the MTJ element 10. The readout word lines RWL are made of, for example, a conductive material such as tungsten.

[0020] A plurality of readout bit lines RBL extend in the Y direction and are arranged in the X direction. In this embodiment, the readout bit lines RBL are disposed above the readout word lines RWL in the Z direction. When data is read from the memory cell MC, current flows through the memory cell MC via the readout bit lines RBL. The readout bit lines RBL are made of, for example, a conductive material such as tungsten.

[0021] One of the source and drain terminals of the write transistor WTr is connected to the write bit line WBL, and the other is connected to the conductive layer C1. The gate of the write transistor WTr is connected to the write word line WWL. Thus, by applying a voltage to the write word line WWL via a write circuit (not shown), the write transistor WTr is controlled to be turned on or off.

[0022] During the write operation, the write transistor WTr is turned on, allowing current to flow between the write bit line WBL and the conductive layer C1. This current flows through the conductive layer C1 between the write bit line WBL and the source line SL as the write current. During the write operation, the read transistor RTr is turned off, blocking the current between the read bit line RBL and the MTJ element 10.

[0023] One of the source and drain terminals of the read transistor RTr is connected to the read bit line RBL, and the other is connected to the upper end of the MTJ element 10. The gate of the read transistor RTr is connected to the read word line RWL. Thus, by applying a voltage to the read word line RWL through a read circuit (not shown), the read transistor RTr is controlled to be turned on or off.

[0024] During the read operation, the read transistor RTr is turned on, allowing current to flow between the read bit line RBL and the MTJ element 10. This current flows through the MTJ element 10 between the read bit line RBL and the source line SL as the read current. During the read operation, the write transistor WTr is turned off, blocking the current between the write bit line WBL and the conductive layer C1.

[0025] As shown in Figure 1, the write transistor WTr and the read transistor RTr are disposed on different layers in the Z direction and are positioned on opposite sides of the Z direction, separated by the MTJ element 10. The write transistor WTr is positioned at the height of the write word line WWL, which is lower than the MTJ element 10. The read transistor RTr is positioned at the height of the read word line RWL, which is higher than the MTJ element 10. Thus, the write transistor WTr and the read transistor RTr are formed separately, allowing for different configurations and characteristics.

[0026] Figure 2 is a top view showing an example of the configuration of the magnetic memory 1 according to the first embodiment. Figure 2 shows the plane of the magnetic memory 1 as viewed from the Z direction. The configuration above the conductive layer C1 is indicated by dashed lines.

[0027] In the XY plane (plane 1), orthogonal to the Z direction, a plurality of write word lines (WWL) and a plurality of read word lines (RWL) extend substantially parallel to each other in the X direction and are arranged in the Y direction. A plurality of write bit lines (WBL) and a plurality of read bit lines (RBL) extend substantially parallel to each other in the Y direction and are arranged in the X direction. Therefore, the plurality of write word lines (WWL) and the plurality of write bit lines (WBL) intersect each other (e.g., orthogonal) when viewed from the Z direction. The plurality of read word lines (RWL) and the plurality of read bit lines (RBL) intersect each other (e.g., orthogonal) when viewed from the Z direction.

[0028] The source line SL extends in the Y direction and is aligned in the X direction.

[0029] A conductive layer C1 is disposed corresponding to each memory cell MC (each MTJ element 10) and is separated for each memory cell MC. The conductive layer C1 extends in the XY plane along a D2 direction inclined relative to the X and Y directions. The D2 direction is the length direction of the conductive layer C1 and also the direction in which the write current flows through the conductive layer C1. The D2 direction is an example of the first direction. The conductive layer C1 extends from above the write transistor WTr, through the MTJ element 10 and below the read transistor RTr, to the contact position of the source line SL. Therefore, the conductive layer C1 is disposed centered on the upper part of the MTJ element 10 between the write transistor WTr and the source line SL. One end of the conductive layer C1 is connected to the source or drain of the write transistor WTr, and the other end is connected to the source line SL.

[0030] The planar dimension of a single memory cell (MC) is relatively small, approximately 6.9 F² (2 F × 3.45 F). F (Feature Size) refers to the characteristic dimension that can be fabricated using lithography and etching techniques. The conductive layer C1 is positioned along the D2 direction, which is inclined relative to the X and Y directions, and the contacts at both ends of the conductive layer C1 are configured in a hexagonal lattice shape. This reduces the size of the memory cell (MC).

[0031] Figure 3 is an equivalent circuit diagram showing an example of the configuration of the magnetic memory 1 according to the first embodiment. A memory cell MC includes a write transistor WTr, a read transistor RTr, and an MTJ element 10. A conductive layer C1 is included in the MTJ element 10. The connection relationships of the write word line WWL, read word line RWL, write bit line WBL, read bit line RBL, MTJ element 10, write transistor WTr, and read transistor RTr are as described above.

[0032] During the data writing operation, multiple write character lines WWL are executed. A voltage is applied to the selected write word line WWLk (where k is any one from 0 to i) (i is an integer), thereby turning on the write transistor WTr connected to the selected write word line WWLk. This activates the write bit line WBL. The write current flows between the source line SL and the write transistor WTr and the conductive layer C1. The write current controls the magnetization direction of the MTJ element 10 and writes data.

[0033] During the data readout operation, multiple readout character lines RWL are used. A voltage is applied to the selected read word line RWLk, thereby turning on the read transistor RTr connected to the selected read word line RWLk. This activates the read bit line RBL. The read current flows between the source line SL and the read current transistor RTr and the MTJ element 10. At this time, the read bit line RBL The voltage becomes the voltage corresponding to the magnetization direction of the MTJ element 10. This is achieved by detecting the readout bit line RBL. The voltage can be used to detect data stored in memory cells (MCs).

[0034] Figure 4 is a cross-sectional view showing an example of the configuration of an MTJ element according to the first embodiment. Figure 5 is a top view showing an example of the configuration of an MTJ element according to the first embodiment.

[0035] The MTJ element 10 includes a first electrode E1, a second electrode E2, a third electrode E3, a non-magnetic conductive layer 11, a first magnetic layer 12, a non-magnetic insulating layer 13, and a second magnetic layer 14. The MTJ element 10 is a three-terminal element having first to third electrodes E1 to E3.

[0036] The first electrode E1 is located on the upper part of the MTJ element 10 and carries current during the read operation. The first electrode E1 is connected to the read bit line RBL. The second and third electrodes E2 and E3 are located on the lower part of the MTJ element 10 and carry write current during the write operation. The second electrode E2 is connected to the write word line WWL. Furthermore, the third electrode E3, connected to the source line SL, also carries current during the read operation. The first to third electrodes E1 to E3 are made of conductive metals such as tungsten.

[0037] A non-magnetic conductive layer 11 is disposed in the +Z direction of the second and third electrodes E2 and E3, and electrically connects the second electrode E2 and the third electrode E3. The non-magnetic conductive layer 11 may be made of a non-magnetic conductive material, such as a heavy metal or topological material exhibiting the SOT effect. Specifically, it may use W, Ta, Pt, Pd, Hf, Ir, Re, Ag, Au, Bi, Sb, Se, Te, Mo, or alloys or compounds containing these materials. The non-magnetic conductive layer 11 functions as a so-called SOT layer. The second and third electrodes E2 and E3 are connected at both ends of the non-magnetic conductive layer 11 and the first magnetic layer 12 in the D2 direction.

[0038] The first magnetic layer 12 is deposited on the non-magnetic conductive layer 11 in the +Z direction. When viewed from the Z direction, the first magnetic layer 12 overlaps with the non-magnetic conductive layer 11 and together they form the conductive layer C1. The first magnetic layer 12 is, for example, made of a 3d transition metal (e.g., any one of Fe, Co, Ni) or an alloy containing such a magnetic conductive material.

[0039] The first magnetic layer 12 is a continuous component having the same shape along its length in the D2 direction. For example, as shown in FIG5, when viewed from the Z direction, the length (width) of the first magnetic layer 12 in the D2 direction is longer than the length (width) of the first magnetic layer 12 in the D3 direction, which intersects (e.g., is orthogonal) the D2 direction. For example, when viewed from the Z direction, the first magnetic layer 12 has a generally rectangular or generally elliptical shape along its length in the D2 direction. The D3 direction is an example of a third direction.

[0040] Furthermore, the first magnetic layer 12 includes the first region R1 and the second region R2 adjacent to each other in the D2 direction.

[0041] The first region R1 of the first magnetic layer 12 is a region with plane-perpendicular magnetic anisotropy where the magnetization direction M1 is along the Z direction or its opposite direction. The first region R1 includes the area in the first magnetic layer 12 where a non-magnetic insulating layer 13 and a second magnetic layer 14 exist in the +Z direction. The upper surface of the first region R1 is in direct contact with the non-magnetic insulating layer 13. Therefore, the first region R1 has plane-perpendicular magnetic anisotropy. That is, the magnetization direction M1 of the first region R1 is either +Z or -Z. Furthermore, the magnetization direction M1 of the first region R1 changes to +Z or -Z depending on the direction of the write current Iw1 flowing through the non-magnetic conductive layer 11 or the first magnetic layer 12. In other words, the first region R1 has plane-perpendicular magnetic anisotropy and functions as a plane-perpendicular magnetization free layer whose magnetization direction M1 can be reversed according to the write current Iw1.

[0042] The second region R2 of the first magnetic layer 12 is a region with in-plane magnetic anisotropy, where the magnetization direction M2 is fixed along the D2 direction. The second region R2 is the region outside the first region R1 of the first magnetic layer 12, and is a region where the non-magnetic insulating layer 13 and the second magnetic layer 14 do not exist in the +Z direction. Since the non-magnetic insulating layer 13 is not provided on the upper surface of the second region R2, the second region R2 of the first magnetic layer 12 has in-plane magnetic anisotropy. That is, the magnetization direction M2 of the second region R2 is a direction that is approximately parallel to the XY plane. Furthermore, when viewed from the Z direction, the second region R2 has a length direction in the D2 direction. For example, when viewed from the Z direction, the second region R2 has a shape that is approximately rectangular or approximately elliptical with a length direction in the D2 direction. Therefore, the magnetization direction M2 of the second region R2 can be fixed to either the +D2 or -D2 direction. For example, by temporarily applying a stronger external magnetic field during shipment, the magnetization direction M2 of the second region R2 of a plurality of MTJ elements 10 can be made to be aligned to the -D2 direction. The shape of the second region R2 is designed so that the magnetization direction M2 does not change with the write current Iw1. Therefore, once the magnetization direction M2 is aligned to the -D2 direction, the magnetization direction M2 will not be reversed by the write current Iw1. As a result, the second region R2 functions as an in-plane magnetization fixing layer with a magnetization direction M2 fixed to the -D2 direction.

[0043] Thus, the first magnetic layer 12 continuously includes a first region R1, which is a free layer for perpendicular magnetization, and a second region R2, which is a fixed layer for in-plane magnetization. Two second regions R2 are arranged with one first region R1 between them, and are respectively positioned in contact with both sides of the first region R1. Therefore, a 90° magnetic wall is formed at the boundary between the first region R1 and the second region R2. The 90° magnetic wall is disposed within the first magnetic layer 12 along the sides of the non-magnetic insulating layer 13 and the second magnetic layer 14. Furthermore, when viewed from the Z direction, as described below, the 90° magnetic wall may also slightly protrude outwards from the sides of the non-magnetic insulating layer 13 and the second magnetic layer 14.

[0044] In this embodiment, the non-magnetic insulating layer 13 is not present in the +Z direction of the second region R2. However, there is no problem as long as the non-magnetic insulating layer 13 exists in the +Z direction of the second region R2 to a degree that does not impair the in-plane magnetic anisotropy of the second region R2 (see Figure 19).

[0045] A non-magnetic insulating layer 13 is disposed in the +Z direction of the first region R1 of the first magnetic layer 12. The non-magnetic insulating layer 13 is disposed in the center of the non-magnetic conductive layer 11 and the first magnetic layer 12 in the D2 direction. The non-magnetic insulating layer 13 of the first magnetic layer 12 uses a non-magnetic insulator such as MgO. The non-magnetic insulating layer 13 imparts planar magnetic anisotropy to the first region R1 of the first magnetic layer 12 and the second magnetic layer 14 in contact with it. The non-magnetic insulating layer 13 functions as a tunneling barrier film for the MTJ element 10.

[0046] The second magnetic layer 14 is disposed between the non-magnetic insulating layer 13 and the first electrode E1. The second magnetic layer 14 is disposed in the +Z direction of the non-magnetic insulating layer 13. When viewed from the Z direction, the second magnetic layer 14 overlaps with the non-magnetic insulating layer 13. Therefore, the second magnetic layer 14, like the non-magnetic insulating layer 13, is disposed in the center of the non-magnetic conductive layer 11 and the first magnetic layer 12 in the D2 direction. For example, the magnetization direction M3 of the second magnetic layer 14 is fixed in the +Z direction, and it has plane perpendicular magnetic anisotropy. Therefore, the second magnetic layer 14 functions as a plane perpendicular magnetization fixing layer (reference layer) of the MTJ element 10.

[0047] The first electrode E1 is disposed in the +Z direction of the second magnetic layer 14, and similarly to the second magnetic layer 14 and the non-magnetic insulating layer 13, it is disposed in the center of the non-magnetic conductive layer 11 and the first magnetic layer 12 in the D2 direction.

[0048] Next, the operation of the magnetic memory 1 in this embodiment will be explained.

[0049] Figures 6 to 11 are diagrams illustrating an example of the operation of the MTJ element according to the first embodiment. Figures 6, 8, and 10 show cross-sections of the MTJ element 10. Figures 7, 9, and 11 show the planes of the MTJ element 10 corresponding to Figures 6, 8, and 10, respectively.

[0050] Figures 6 and 7 show the magnetization direction of the MTJ element 10 in its initial state. In the initial state, the magnetization direction M1 of the first region R1 is oriented towards the -Z direction. The magnetization direction M2 of the second region R2 is fixed in the -D2 direction. The magnetization direction M3 of the second magnetic layer 14 is fixed in the +Z direction.

[0051] When the write current Iw1 flows from the second electrode E2 to the third electrode E3 (in the -D2 direction), the magnetization direction M1 of the first region R1 reverses to the +Z direction. In this case, as shown in Figures 8 and 9, when the write current Iw1 flows in the -D2 direction through the first magnetic layer 12, the magnetization direction M1 begins to reverse at the boundary between the first region R1 and the second region R2. This is because the magnetization of the second region R2 in the magnetization direction M2 generates (leakage) an effective magnetic field to the first region R1, inducing a reversal of the magnetization direction M1 in the first region R1 from the vicinity of the boundary between the unstable magnetization structure of the first region R1 and the second region R2. That is, the same effect as applying an external magnetic field to the magnetization of the second region R2 is applied to the first region R1, inducing a magnetization reversal. Thus, as shown in Figures 8 and 9, the reversal of the magnetization direction M1 of the first region R1 begins at the boundary between the first region R1 and the second region R2, and extends toward the interior of the first region R1.

[0052] Before the magnetization direction M1 of region 1 R1 is completely reversed, the write current Iw1 can be stopped midway. Once the reversal of the magnetization direction M1 begins at the boundary between region 1 R1 and region 2 R2, the reversal will continue for a certain period and be transmitted to the center of region 1 R1. Therefore, even if the write current Iw1 is stopped midway before the magnetization direction M1 is completely reversed, as shown in Figures 10 and 11, the magnetization direction M1 of region 1 R1 can still be reversed to the -Z direction.

[0053] Of course, the write current Iw1 can also be flowed until the reversal of the magnetization direction M1 of the first region R1 is completed. For example, when the length of the D2 direction of the first region R1 is small, since the reversal of the magnetization direction M1 is completed in a short time, the write current Iw1 can be stopped after the reversal of the magnetization direction M1 of the first region R1 is completed.

[0054] To reverse the magnetization direction M1 of region R1 from +Z to -Z, simply allow the write current Iw1 to flow from the third electrode E3 to the second electrode E2 (in the +D2 direction).

[0055] According to this embodiment, the first magnetic layer 12 includes a first region R1, which is a plane-perpendicular magnetization free layer having plane-perpendicular magnetic anisotropy and a reversible magnetization direction M1, and a second region R2, which is an in-plane magnetization fixed layer having in-plane magnetic anisotropy and a fixed magnetization direction M2. The second region R2 is adjacent to the first region R1 on both sides, and the boundary between them is a continuous film. The magnetization of the second region R2 has the same effect as applying an external magnetic field to the first region R1, and efficiently induces the magnetization reversal of the first region R1. In this way, without applying an external magnetic field, the magnetization direction M1 of the first region R1 can be reversed with a relatively small write current Iw1. The magnetic memory 1 of this embodiment, for example, does not require the external magnetic field required by the perpendicular magnetization mode (type-z) SOT-MRAM, and can reduce the write current more than that of type-z SOT-MRAM.

[0056] Furthermore, no non-magnetic insulating layer 13 is provided on the second region R2 of the first magnetic layer 12. Alternatively, even if a non-magnetic insulating layer 13 is provided on the second region R2, the non-magnetic insulating layer 13 does not hinder the in-plane magnetic anisotropy of the second region R2. Therefore, the film quality of the non-magnetic insulating layer 13 on the second region R2 is poor, and it may contain more crystal defects. In this way, the second region R2 of the first magnetic layer 12 can have in-plane magnetic anisotropy, and the magnetization direction M2 can be fixed according to its shape, etc.

[0057] On the other hand, in magnetic walled MRAMs, the tunneling barrier layer is not only located in the free layer directly below the reference layer, but also in the free layers beyond the reference layer to ensure that the other free layers are perpendicular to the magnetic anisotropy. In this case, when the free layers beyond the reference layer lose their perpendicular magnetic anisotropy, the magnetic walled moving layer cannot function. Therefore, in order to maintain perpendicular magnetic anisotropy in the free layers beyond the reference layer, the thickness of the tunneling barrier layer in the free layers beyond the reference layer must be sufficient, and its film quality must also be good.

[0058] In this embodiment, since the second region R2 of the first magnetic layer 12 can have in-plane magnetic anisotropy, a non-magnetic insulating layer 13 is not required on the second region R2. Alternatively, the non-magnetic insulating layer 13 on the second region R2 can also be a thin film with a thickness and deterioration that does not hinder the in-plane magnetic anisotropy of the second region R2. Furthermore, since the magnetic memory 1 of this embodiment does not require the generation (pinning) of magnetic walls, its structure is simpler compared to magnetic wall MRAM.

[0059] Furthermore, in this embodiment, the magnetization direction M2 of the second region R2 is fixed according to the shape of the second region R2. However, the method for fixing the magnetization direction M2 of the second region R2 is not limited to this.

[0060] For example, in the process of forming the first magnetic layer 12, by applying a magnetic field while forming the first magnetic layer 12, in-plane magnetic anisotropy can be imparted to the first magnetic layer 12, and the magnetization direction M2 of the second region R2 can be fixed. In this case, the first region R1 forming the non-magnetic insulating layer 13 can maintain its planar magnetic anisotropy because it has a planar magnetic anisotropy perpendicular to the interface with the non-magnetic insulating layer 13.

[0061] Furthermore, for example, as shown in Figure 2, the magnetization direction M2 of the second region R2 can be fixed according to the layout of the MTJ elements 10. In Figure 2, a plurality of MTJ elements 10 are arranged along the length direction (D2 direction) of the conductive layer C1. The plurality of MTJ elements 10 are arranged in a plane including the D2 and D3 directions, or in a plane including the X and Y directions. By arranging the plurality of MTJ elements 10 along the length direction (D2 direction) of the conductive layer C1, leakage flux is generated in a manner that penetrates along the length direction of the conductive layer C1 of the plurality of memory cells MC. In this way, the magnetization direction M2 of the second region R2 of the first magnetic layer 12 can be strengthened and fixed. The narrower the spacing between the plurality of conductive layers C1 arranged along the D2 direction, the more strengthened and fixed the magnetization direction M2 of the second region R2 can be. Therefore, the spacing between the plurality of conductive layers C1 arranged along the D2 direction is preferably narrower.

[0062] (Second Implementation) Figure 12 is a cross-sectional view showing an example of the configuration of an MTJ element according to the second embodiment. The second embodiment further includes a third magnetic layer 15 and a fourth magnetic layer 16.

[0063] The third magnetic layer 15 is disposed between the second electrode E2 and the non-magnetic conductive layer 11. The fourth magnetic layer 16 is disposed between the third electrode E3 and the non-magnetic conductive layer 11. The third and fourth magnetic layers 15 and 16 are both fixed layers with a magnetization direction M4 opposite to the magnetization direction M2 of the second region R2 of the first magnetic layer 12, and the magnetization direction does not change according to the write current Iw1.

[0064] The magnetization directions of the third and fourth magnetic layers 15 and 16 are determined in a way that closes the leakage magnetic flux generated between them and the first magnetic layer 12. In this way, the magnetization direction M2 of the second region R2 of the first magnetic layer 12 can be fixed.

[0065] The third and fourth magnetic layers 15 and 16 are the same layer, and the material can also be the same. Therefore, the structure of the second embodiment is simpler than that of a magnetic wall MRAM. Furthermore, the third and fourth magnetic layers 15 and 16 can be formed by the same process, so the manufacturing process of the second embodiment is also simpler than that of a magnetic wall MRAM.

[0066] The other components of the second embodiment can be the same as those of the first embodiment. Therefore, the second embodiment can achieve the same effects as the first embodiment.

[0067] (Third Implementation) Figure 13 is a top view showing an example of the configuration of the magnetic memory 1 according to the third embodiment. Figure 13 shows the planar view of the magnetic memory 1 viewed from the Z direction. The configuration above the conductive layer C1 is indicated by dashed lines.

[0068] In the third embodiment, the conductive layer C1 is continuous and connected among a plurality of MTJ elements 10 arranged in the D2 direction. In the conductive layer C1, the magnetization direction M2 of the second region R2 of the first magnetic layer 12 is in the same direction (e.g., the -D2 direction). Therefore, among the plurality of MTJ elements 10 arranged in the D2 direction, the conductive layer C1 can be configured as a continuous conductive layer extending in the D2 direction. By sharing the conductive layer C1 in the D2 direction and forming it as a continuous conductive layer, the magnetization direction M2 of the second region R2 of the first magnetic layer 12 can be further strengthened and fixed.

[0069] The other components of the third embodiment can be the same as those of the first embodiment. Therefore, the third embodiment can achieve the same effects as the first embodiment. Furthermore, the third embodiment can also be combined with the second embodiment.

[0070] (Example of variation) Figures 14 and 15 are top views showing examples of the configuration of the MTJ element according to variations of the above embodiments.

[0071] In the variation of Figure 14, a portion of the second region R2 of the first magnetic layer 12 includes a third region R3 with plane perpendicular magnetic anisotropy. The magnetization direction of the third region R3 may be fixed or not. The third region R3 does not contact the boundary between the first region R1 and the second region R2. In this case, the effective magnetic field imparted to the first region R1 by the magnetization direction M2 of the second region R2 is not lost. Therefore, a portion of the second region R2 may also include a third region R3 with plane perpendicular magnetic anisotropy.

[0072] In the variation shown in Figure 15, when viewed from the Z direction, the first region R1 of the first magnetic layer 12 slightly protrudes from the non-magnetic insulating layer 13 and the second magnetic layer 14 towards the second region R2. That is, the boundary between the first region R1 and the second region R2 is slightly offset outward from the side of the non-magnetic insulating layer 13 and the second magnetic layer 14. Even in this case, when viewed from the Z direction, since the effective area of ​​the first region R1 overlapping with the non-magnetic insulating layer 13 and the second magnetic layer 14 remains unchanged, the magnetization written to the MTJ element 10 is maintained. Therefore, the effect of this embodiment is not lost.

[0073] However, conversely, when viewed from the Z direction, as the second region R2 protrudes from the non-magnetic insulating layer 13 and the second magnetic layer 14 toward the first region R1, the effective area of ​​the first region R1 overlapping with the non-magnetic insulating layer 13 and the second magnetic layer 14 becomes smaller, resulting in a smaller magnetization when written into the MTJ element 10. Therefore, the offset of the boundary between R1 and R2 from the side of the non-magnetic insulating layer 13 and the second magnetic layer 14 toward the inside of the first region R1 is undesirable.

[0074] Figures 16 and 17 are cross-sectional views showing a configuration example of the MTJ element according to another variation of the above-described embodiment. As shown in Figure 16, when viewed from the Z direction, a portion of the first region R1 may also overlap with the lower electrode E3. As shown in Figure 17, when viewed from the Z direction, the entire first region R1 may also overlap with the lower electrode E3. Even with this configuration, the effects of this embodiment are not lost.

[0075] Figure 18 is a top view showing an example of the configuration of an MTJ element according to another variation of the above embodiment. The width of the upper electrode E1 and the lower electrodes E2 and E3 in the D3 direction can also be narrower than the width of the conductive layer C1 in the D3 direction. Even with this configuration, the effect of this embodiment will not be lost.

[0076] Figure 19 is a cross-sectional view showing an example of the configuration of an MTJ element according to another variation of the above-described embodiment. There is no problem as long as the non-magnetic insulating layer 13 exists in the +Z direction of the second region R2 to a degree that does not impair the in-plane magnetic anisotropy of the second region R2. For example, if the film thickness of the non-magnetic insulating layer 13 on the upper surface of the second region R2 is thinner than the film thickness of the non-magnetic insulating layer 13 located on the upper surface of at least the first region R1, the non-magnetic insulating layer 13 can still exist on the upper surface of the second region R2 when the second region R2 has in-plane magnetic anisotropy. Furthermore, for example, if the crystal defects contained in the non-magnetic insulating layer 13 on the upper surface of the second region R2 are more numerous than those contained in the non-magnetic insulating layer 13 located on the upper surface of at least the first region R1, the non-magnetic insulating layer 13 can still exist on the upper surface of the second region R2 when the second region R2 has in-plane magnetic anisotropy.

[0077] Figure 20 is a cross-sectional view showing a configuration example of an MTJ element according to another variation of the above embodiment. In this variation, compared with the configuration example in Figure 17, the lower electrode E3 is offset towards the lower electrode E2, and at the end opposite to the lower electrode E2, a portion of the non-magnetic conductive layer 11, the first magnetic layer 12, the non-magnetic insulating layer 13, the second magnetic layer 14, and the first electrode E1 protrudes. In this case, since no current flows through the protruding portion, the magnetization reversal efficiency is reduced. However, if, for example, the protruding portion is less than half the width of the lower electrode E3 in the D2 direction, the reduction in magnetization reversal efficiency is within an acceptable range. Therefore, even with this configuration, the effects of this embodiment are not lost.

[0078] Several embodiments of the present invention have been described, but these embodiments are provided as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments or variations thereof are included in the scope or spirit of the invention, and likewise included in the invention described in the claims and its equivalents.

[0079] 1: Magnetic memory 10: MTJ components 11: Non-magnetic conductive layer 12: First magnetic layer 13: Non-magnetic insulating layer 14: Second magnetic layer 15: Third magnetic layer 16: Fourth magnetic layer C1: Conductive layer D2: Direction D3: direction E1: First electrode E2: Second electrode E3: Third electrode Iw1: Write current M1: Magnetization direction M2: Magnetization direction M3: Magnetization direction M4: Magnetization direction MC: Memory Cell R1: Region 1 R2: Region 2 R3: Area 3 RBL: Readout bitline RBL <0> Read out bit lines RBL <1> Read out bit lines RTr: Readout transistor RWL: Read out character lines RWL <0> Read out the character lines RWL <1> Read out the character lines RWL <2> Read out the character lines SL: Source Line SL <0> Source line SL <1> Source line WBL: Write Bit Line WBL <0> Write bit line WBL <1> Write bit line WTr: Write transistor WWL: Write character line WWL <0> Write character lines WWL <1> Write character lines WWL <2> Write character lines X: Direction Y: direction Z: Direction +Z: Direction -Z: Direction

Claims

1. A magnetic memory comprising: a first electrode; a second electrode and a third electrode arranged at equal intervals in the first direction; a non-magnetic conductive layer electrically connecting the second electrode and the third electrode and extending in the first direction; a first magnetic layer disposed relative to the non-magnetic conductive layer in the second direction intersecting the first direction, the first magnetic layer extending in the first direction and including a first region and a second region arranged along the first direction, at least a portion of the first region being disposed in the second direction between the first electrode and the non-magnetic conductive layer; a second magnetic layer disposed between the first region and the first electrode; and a non-magnetic insulating layer disposed between the first magnetic layer and the second magnetic layer; wherein, when viewed from the second direction, the first electrode is disposed between the second electrode and the third electrode, at a position where at least a portion overlaps with the second electrode, or at a position where at least a portion overlaps with the third electrode. When viewed from the second direction, the thickness of the portion of the non-magnetic insulating layer that overlaps with the second region is thinner than the thickness of the portion that overlaps with the first region.

2. A magnetic memory comprising: a first electrode; a second electrode and a third electrode arranged at equal intervals in the first direction; a non-magnetic conductive layer electrically connecting the second electrode and the third electrode and extending in the first direction; a first magnetic layer disposed relative to the non-magnetic conductive layer in the second direction intersecting the first direction, the first magnetic layer extending in the first direction and including a first region and a second region arranged along the first direction, at least a portion of the first region being disposed in the second direction between the first electrode and the non-magnetic conductive layer; a second magnetic layer disposed between the first region and the first electrode, and having a magnetization direction fixed along the second direction; and a non-magnetic insulating layer disposed between the first magnetic layer and the second magnetic layer. When viewed from the second direction, the first electrode is positioned between the second electrode and the third electrode, at least partially overlapping with the second electrode, or at least partially overlapping with the third electrode. The magnetization direction of the first region is variable along the second direction, and the magnetization direction of the second region is fixed along the first direction.

3. A magnetic memory comprising a first magnetoresistive element and a second magnetoresistive element, wherein the first magnetoresistive element and the second magnetoresistive element respectively comprise: a first electrode; a second electrode and a third electrode, which are arranged at equal intervals in the first direction; a non-magnetic conductive layer electrically connecting the second electrode and the third electrode and extending in the first direction; a first magnetic layer disposed relative to the non-magnetic conductive layer in a second direction intersecting the first direction, the first magnetic layer extending in the first direction and comprising a first region and a second region arranged along the first direction, at least a portion of the first region being disposed in the second direction between the first electrode and the non-magnetic conductive layer; a second magnetic layer disposed between the first region and the first electrode; and a non-magnetic insulating layer disposed between the first magnetic layer and the second magnetic layer. When viewed from the second direction, the first electrode is disposed between the second and third electrodes, at least partially overlapping with the second electrode, or at least partially overlapping with the third electrode. The first and second magnetoresistive elements are disposed in a plane including a third direction that intersects the first and second directions. When viewed from the second direction, the non-magnetic conductive layer of the first magnetoresistive element is continuous and connected to the non-magnetic conductive layer of the second magnetoresistive element, and the first magnetic layer of the first magnetoresistive element is continuous and connected to the first magnetic layer of the second magnetoresistive element.

4. The magnetic memory as requested in item 2 or 3, wherein the non-magnetic insulating layer is not provided in the second direction of the second region.

5. In any of the claims 1 to 3, the non-magnetic insulating layer, when viewed from the second direction, has more crystal defects in the portion overlapping with the second region compared to the portion overlapping with the first region.

6. The magnetic memory of any one of claims 1 to 3, wherein when viewed from the second direction, the length direction of the first magnetic layer is the first direction.

7. A magnetic memory as claimed in any of claims 1 to 3, wherein the first direction is the direction in which write current flows through the non-magnetic conductive layer or the first magnetic layer, and when viewed from the second direction, the length of the first magnetic layer in the first direction is longer than the length of the first magnetic layer in the third direction, which intersects the first and second directions.

8. A magnetic memory as claimed in any of claims 1 to 3, wherein the first magnetic layer comprises a plurality of the second regions, and the plurality of second regions are disposed on both sides of the first region in the first direction.

9. The magnetic memory as claimed in any of claims 1 to 3, wherein the first region is characterized by a magnetization direction that varies according to the direction of the write current flowing to the non-magnetic conductive layer or the first magnetic layer, and the second region is characterized by a magnetization direction that does not vary according to the write current.

10. A magnetic memory as claimed in any one of claims 1 to 3, wherein the second electrode and the third electrode are connected to both ends of the non-magnetic conductive layer and the first magnetic layer in the first direction, and the non-magnetic insulating layer, the second magnetic layer and the first electrode are disposed at the center of the non-magnetic conductive layer and the first magnetic layer in the first direction.

11. The magnetic memory of any one of claims 1 to 3, wherein at least a portion of the second region overlaps with the second electrode in the second direction.

12. A magnetic memory according to any one of claims 1 to 3, comprising: a source wiring connected to the third electrode; a write wiring connected to the second electrode; and a read wiring connected to the first electrode; wherein the first direction is a direction inclined relative to the source wiring, the write wiring and the read wiring.

13. The magnetic memory according to any one of claims 1 to 3 further comprises: a third magnetic layer disposed between the second electrode and the non-magnetic conductive layer; and a fourth magnetic layer disposed between the third electrode and the non-magnetic conductive layer.

14. The magnetic memory of claim 13, wherein the third magnetic layer and the fourth magnetic layer have a magnetization direction opposite to the magnetization direction in the second region, and the magnetization direction does not change according to the write current flowing through the non-magnetic conductive layer or the first magnetic layer.

15. The magnetic memory of claim 1 or 2, wherein the magnetic memory comprises at least a first magnetoresistive element and a second magnetoresistive element, wherein the first magnetoresistive element and the second magnetoresistive element respectively comprise: the first electrode, the second electrode, the third electrode, the non-magnetic conductive layer, the first magnetic layer, the non-magnetic insulating layer and the second magnetic layer, wherein the first magnetoresistive element and the second magnetoresistive element are disposed in a plane including a third direction intersecting the first direction and the second direction.

16. The magnetic memory of claim 15, wherein, when viewed from the second direction, the non-magnetic conductive layer and the first magnetic layer are separated by each of the magnetoresistive elements.

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