Magnetic memory
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- KIOXIA CORP
- Filing Date
- 2025-07-30
- Publication Date
- 2026-08-07
Smart Images
Figure CN122534880A_ABST
Abstract
Description
Technical Field
[0001] This embodiment relates to a magnetic storage device. Background 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 storage 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 the tunnel barrier layer, or require complex fixed layer structures to pin the magnetic walls. Summary of the Invention
[0005] The present 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 along 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 along 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 being disposed between the first electrode and the non-magnetic conductive layer in the second direction. 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 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. 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. Attached Figure Description
[0007] Figure 1 This is a perspective view showing a configuration example of the magnetic storage device according to the first embodiment.
[0008] Figure 2 This is a top view showing a configuration example of the magnetic storage according to the first embodiment.
[0009] Figure 3This is an equivalent circuit diagram showing a configuration example of the magnetic memory in the first embodiment.
[0010] Figure 4 This is a cross-sectional view showing a configuration example of an MTJ element according to the first embodiment.
[0011] Figure 5 This is a top view showing a configuration example of an MTJ element according to the first embodiment.
[0012] Figure 6 This is a diagram illustrating an example of the operation of the MTJ element according to the first embodiment.
[0013] Figure 7 This is a diagram illustrating an example of the operation of the MTJ element according to the first embodiment.
[0014] Figure 8 This is a diagram illustrating an example of the operation of the MTJ element according to the first embodiment.
[0015] Figure 9 This is a diagram illustrating an example of the operation of the MTJ element according to the first embodiment.
[0016] Figure 10 This is a diagram illustrating an example of the operation of the MTJ element according to the first embodiment.
[0017] Figure 11 This is a diagram illustrating an example of the operation of the MTJ element according to the first embodiment.
[0018] Figure 12 This is a cross-sectional view showing a configuration example of an MTJ element according to the second embodiment.
[0019] Figure 13 This is a top view showing a configuration example of the magnetic storage device according to the third embodiment.
[0020] Figure 14 This is a top view showing a configuration example of the MTJ element according to a variation of the described embodiment.
[0021] Figure 15 This is a top view showing a configuration example of the MTJ element according to a variation of the described embodiment.
[0022] Figure 16 This is a cross-sectional view showing an example of the configuration of an MTJ element according to another variation of the described embodiment.
[0023] Figure 17 This is a cross-sectional view showing an example of the configuration of an MTJ element according to another variation of the described embodiment.
[0024] Figure 18This is a top view showing an example of the configuration of an MTJ element according to another variation of the described embodiment.
[0025] Figure 19 This is a cross-sectional view showing an example of the configuration of an MTJ element according to another variation of the described embodiment.
[0026] Figure 20 This is a cross-sectional view showing an example of the configuration of an MTJ element according to another variation of the described embodiment. Detailed Implementation
[0027] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. These embodiments do not limit the present invention. The drawings are schematic diagrams or conceptual diagrams. In the specification and drawings, the same elements are labeled with the same symbols.
[0028] In this specification, the term "intersecting" relative to a certain direction includes the condition that the objects are orthogonal relative to that direction. Conversely, the term "tilting" relative to a certain direction means that the objects are not orthogonal relative to that direction.
[0029] (First Embodiment)
[0030] The magnetic memory in the first embodiment is a magnetic memory that utilizes the spin Hall effect or spin-orbit coupling, specifically a SOT-MRAM that uses spin-orbit torque (SOT) to reverse the magnetization direction of the storage layer. Hereinafter, an example of applying this embodiment to SOT-MRAM will be described. Furthermore, this embodiment can also be applied to magnetic wall MRAM.
[0031] Figure 1 This 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.
[0032] 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 first plane that intersects (e.g., is orthogonal) the X direction. In this embodiment, the +Z direction will be described from the top.
[0033] The 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 arranged in layers with different horizontal heights 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 separated from each other.
[0034] Multiple write bit lines WBL extend along the Y direction and are arranged in the X direction. In this embodiment, the write bit lines WBL are arranged at the bottom layer in the Z direction. When data is written to the memory cell MC, the write bit lines WBL allow the current corresponding to the data to flow in the memory cell MC. For example, they are made of a conductive material such as tungsten.
[0035] Multiple write word lines (WWLs) extend along the X direction and are arranged in the Y direction. In this embodiment, the write word lines (WWLs) are positioned above the write bit lines (WBLs) in the Z direction. When data is written to the memory cell MC, the write word lines (WWLs) turn on the write transistor (WTr), allowing current to flow in the conductive layer C1 of the MTJ element 10. The write word lines (WWLs) are, for example, made of a conductive material such as tungsten.
[0036] Multiple source lines SL extend along the Y direction and are arranged in the X direction. In this embodiment, the source lines SL are positioned 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 multiple source lines SL can be fixed to a common voltage or set to individual different voltages.
[0037] The MTJ element 10, acting as a magnetoresistive element, is a 3-terminal device. 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.
[0038] Multiple MTJ elements 10 are disposed above the write bit line WBL, the write word line WWL, and the source line SL in the Z direction (+Z direction). The conductive layer C1 of the MTJ elements 10 allows current to flow between the write bit line WBL and the source line SL during a write operation, or allows current to flow through the MTJ elements 10 between the read bit line RBL and the source line SL during a read operation. The conductive layer C1 is, for example, made of a non-magnetic conductive layer (…). Figure 4 11) and magnetic conductive layer ( Figure 4 The MTJ element 10 is composed of a multilayer structure (12). A more detailed description of the structure of the MTJ element 10 will be given below.
[0039] Multiple read word lines RWL extend along the X direction and are arranged in the Y direction. In this embodiment, the read word lines RWL are positioned above the MTJ element 10 in the Z direction. When data is read from the memory cell MC, the read word lines RWL turn on the read transistor RTR, allowing current to flow between the read bit line RBL and the source line SL via the MTJ element 10. The read word lines RWL are made of a conductive material such as tungsten.
[0040] Multiple read bit lines RBL extend along the Y direction and are arranged in the X direction. In this embodiment, the read bit lines RBL are positioned above the read word lines RWL in the Z direction. When data is read from the memory cell MC, the read bit lines RBL allow current to flow through the memory cell MC. The read bit lines RBL are made of a conductive material such as tungsten.
[0041] One of the source and drain 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 through a write circuit (not shown), the write transistor WTr is controlled to be turned on or off.
[0042] 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 as the write current between the write bit line WBL and the source line SL via the conductive layer C1. 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.
[0043] One of the source and drain of the read transistor RTr is connected to the read bit line RBL, and the other is connected to the upper end of 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.
[0044] 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, serving as the read current between the read bit line RBL and the source line SL. 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.
[0045] like Figure 1 As shown, 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.
[0046] Figure 2 This is a top view showing a configuration example of the magnetic storage 1 according to the first embodiment. Figure 2 The plane of the magnetic storage device 1 is shown as viewed from the Z direction. The structure above the conductive layer C1 is indicated by dashed lines.
[0047] In the XY plane (plane 1), orthogonal to the Z direction, multiple write word lines (WWL) and multiple read word lines (RWL) extend substantially parallel to each other along the X direction and are arranged in the Y direction. Multiple write bit lines (WBL) and multiple read bit lines (RBL) extend substantially parallel to each other along the Y direction and are arranged in the X direction. Therefore, the multiple write word lines (WWL) and multiple write bit lines (WBL) intersect each other (e.g., orthogonal) when viewed from the Z direction. The multiple read word lines (RWL) and multiple read bit lines (RBL) intersect each other (e.g., orthogonal) when viewed from the Z direction.
[0048] The source line SL extends along the Y direction and is arranged in the X direction.
[0049] 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 that is 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 is disposed 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 between the write transistor WTr and the source line SL with the upper part of the MTJ element 10 as the center. 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.
[0050] The planar dimension of one unit of the memory cell (MC) is relatively small, approximately 6.9F. 2 (2F×3.45F). F (Feature Size) is the size of the feature that can be processed using photolithography and etching techniques. By setting the conductive layer C1 in the D2 direction, which is tilted relative to the X and Y directions, the contacts at both ends of the conductive layer C1 are configured in a hexagonal lattice shape. As a result, the size of the memory cell MC can be reduced.
[0051] Figure 3 This is an equivalent circuit diagram showing a configuration example of the magnetic memory 1 according to the first embodiment. One 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.
[0052] During the data writing operation, a voltage is applied to the selected write word line WWLk (k is any one from 0 to i) among multiple write word lines WWL (i is an integer), thereby turning on the write transistor WTr connected to the selected write word line WWLk. This allows write current to flow between the write bit line WBL and the source line SL, through the write transistor WTr and the conductive layer C1. The write current controls the magnetization direction of the MTJ element 10, thus writing data.
[0053] During the data readout operation, a voltage is applied to the selected read word line RWLk among the multiple read word lines RWL, turning on the readout transistor RTr connected to the selected read word line RWLk. This allows readout current to flow between the readout bit line RBL and the source line SL, through the readout transistor RTr and the MTJ element 10. At this time, the voltage on the readout bit line RBL corresponds to the magnetization direction of the MTJ element 10. By detecting the voltage on the readout bit line RBL, the data stored in the memory cell MC can be detected.
[0054] Figure 4 This is a cross-sectional view showing a configuration example of an MTJ element according to the first embodiment. Figure 5 This is a top view showing a configuration example of an MTJ element according to the first embodiment.
[0055] 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 the first to third electrodes E1 to E3.
[0056] 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. Additionally, the third electrode E3, connected to the source line SL, also carries current during the read operation. Electrodes E1 to E3 are, for example, made of a conductive metal such as tungsten.
[0057] 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. 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.
[0058] The first magnetic layer 12 is deposited in the +Z direction of the non-magnetic conductive layer 11. 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 these materials, which are magnetically conductive materials.
[0059] The first magnetic layer 12 is a continuous component having the same shape along its length in the D2 direction. For example, as... Figure 5 As shown, when viewed from the Z direction, the length 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 shape that is approximately rectangular, approximately elliptical, etc., with its length direction in the D2 direction. The D3 direction is an example of the third direction.
[0060] In addition, the first magnetic layer 12 includes a first region R1 and a second region R2 that are adjacent in the D2 direction.
[0061] 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 a region 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 where the magnetization direction M1 can be reversed according to the write current Iw1.
[0062] 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 of the first magnetic layer 12 other than the first region R1, 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, etc., with a length direction in the D2 direction. Thus, the second region R2 can have its magnetization direction M2 fixed to either the +D2 or -D2 direction. For example, by temporarily applying a strong external magnetic field during shipment, the magnetization direction M2 of the second region R2 of multiple MTJ elements 10 can 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.
[0063] Thus, the first magnetic layer 12 continuously includes a first region R1 as a plane-perpendicular magnetization free layer and a second region R2 as an in-plane magnetization fixed layer within the same layer. 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 side surfaces 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 outward from the side surfaces of the non-magnetic insulating layer 13 and the second magnetic layer 14.
[0064] 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 reference). Figure 19 ).
[0065] 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 D2 direction at the center of the non-magnetic conductive layer 11 and the first magnetic layer 12. 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 tunnel barrier film for the MTJ element 10.
[0066] 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. The second magnetic layer 14, for example, has its magnetization direction M3 fixed in the +Z direction and 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.
[0067] 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.
[0068] Next, the operation of the magnetic storage 1 in this embodiment will be explained.
[0069] Figures 6 to 11This is a diagram illustrating an example of the operation of the MTJ element according to the first embodiment. Figure 6 , Figure 8 as well as Figure 10 This represents the cross-section of MTJ element 10. Figure 7 , Figure 9 as well as Figure 11 Respectively represent and Figure 6 , Figure 8 as well as Figure 10 The plane corresponding to MTJ component 10.
[0070] Figure 6 as well as Figure 7 The magnetization direction of the MTJ element 10 in its initial state is shown. 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.
[0071] 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 is reversed to the +Z direction. In this case, as... Figure 8 as well as Figure 9 As shown, when the write current Iw1 flows in the -D2 direction in 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 (leaks) an effective magnetic field to the first region R1, inducing a magnetization reversal of the magnetization direction M1 in the first region R1 from the vicinity of the boundary between the first region R1 and the second region R2, where the magnetization structure is unstable. In other words, applying an external magnetic field to the first region R1 has the same effect as applying an external magnetic field to the magnetization of the second region R2, inducing a magnetization reversal. Thus, as... Figure 8 as well as Figure 9 As shown, the reversal of the magnetization direction M1 of region 1 R1 starts from the boundary between region 1 R1 and region 2 R2 and extends toward the interior of region 1 R1.
[0072] The write current Iw1 can be stopped midway before the magnetization direction M1 of region 1 R1 is completely reversed. Once the reversal of the magnetization direction M1 begins at the boundary between region 1 R1 and region 2 R2, its reversal action 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, it will still be as before. Figure 10 as well as Figure 11 As shown, the magnetization direction M1 of region R1 can still be reversed to the -Z direction.
[0073] 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, if the length of the first region R1 in the D2 direction 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.
[0074] To reverse the magnetization direction M1 of region R1 from +Z to -Z, simply make the write current Iw1 flow from the third electrode E3 to the second electrode E2 (in the +D2 direction).
[0075] 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 capable of reversing the 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 both sides of the first region R1, and there is a continuous film at its boundary. 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. Thus, 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 vertical magnetization mode (type-z) SOT-MRAM, and can reduce the write current more than that of type-z SOT-MRAM.
[0076] 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. As a result, 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.
[0077] On the other hand, in magnetic wall MRAMs, the tunnel 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 perpendicular magnetic anisotropy. In this case, when the free layers beyond the reference layer lose their perpendicular magnetic anisotropy, the magnetic wall moving layer cannot function. Therefore, to maintain perpendicular magnetic anisotropy in the free layers beyond the reference layer, the tunnel barrier layer located in the free layers beyond the reference layer must be sufficiently thick and of good quality.
[0078] 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.
[0079] 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.
[0080] 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.
[0081] Additionally, for example, such as Figure 2 As shown, the magnetization direction M2 of the second region R2 can also be fixed according to the layout configuration of the MTJ element 10. Figure 2 In this configuration, multiple MTJ elements 10 are arranged along the length direction (D2 direction) of the conductive layer C1. The multiple MTJ elements 10 are arranged in a plane including both the D2 and D3 directions, or in a plane including both the X and Y directions. By arranging the multiple 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 multiple memory cells MC. This strengthens and fixes the magnetization direction M2 of the second region R2 of the first magnetic layer 12. The narrower the spacing between the multiple conductive layers C1 arranged along the D2 direction, the more effectively the magnetization direction M2 of the second region R2 is fixed. Therefore, the spacing between the multiple conductive layers C1 arranged along the D2 direction is preferably narrow.
[0082] (Second Implementation)
[0083] Figure 12 This is a cross-sectional view showing a configuration example of an MTJ element according to the second embodiment. The second embodiment also includes a third magnetic layer 15 and a fourth magnetic layer 16.
[0084] 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 fixed layers that have 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.
[0085] 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. As a result, the magnetization direction M2 of the second region R2 of the first magnetic layer 12 can be fixed.
[0086] 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. In addition, 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.
[0087] The other configurations 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.
[0088] (Third Implementation)
[0089] Figure 13 This is a top view showing a configuration example of the magnetic storage 1 according to the third embodiment. Figure 13 The plane of the magnetic storage device 1 is shown as viewed from the Z direction. The structure above the conductive layer C1 is indicated by dashed lines.
[0090] In the third embodiment, the conductive layer C1 is continuous and connected among the 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 along 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.
[0091] The other configurations 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. In addition, the third embodiment can also be combined with the second embodiment.
[0092] (Example of variation)
[0093] Figure 14 as well as Figure 15This is a top view showing a configuration example of the MTJ element according to a variation of the described embodiment.
[0094] exist Figure 14 In a variation, a portion of the second region R2 in the first magnetic layer 12 includes a third region R3 with planar magnetic anisotropy. The magnetization direction of the third region R3 can 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 planar magnetic anisotropy.
[0095] exist Figure 15 In the variation example, 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 effects of this embodiment are not lost.
[0096] 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, it is undesirable for the boundary between R1 and R2 to shift from the side of the non-magnetic insulating layer 13 and the second magnetic layer 14 toward the inside of the first region R1.
[0097] Figure 16 as well as Figure 17 This is a cross-sectional view showing an example of the configuration of an MTJ element according to another variation of the described embodiment. For example... Figure 16 As shown, when viewed from the Z direction, a portion of region R1 can also overlap with the lower electrode E3. Figure 17 As shown, when viewed from the Z direction, the entire first region R1 can overlap with the lower electrode E3. Even with this configuration, the effect of this embodiment is not lost.
[0098] Figure 18This is a top view showing an example of the configuration of an MTJ element according to another variation of the described embodiment. The width in the D3 direction of the upper electrode E1 and the lower electrodes E2 and E3 may also be narrower than the width in the D3 direction of the conductive layer C1. Even with such a configuration, the effects of this embodiment will not be lost.
[0099] Figure 19 This is a cross-sectional view showing an example of the configuration of an MTJ element according to another variation of the 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 may still exist on the upper surface of the second region R2 if 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 may still exist on the upper surface of the second region R2 if the second region R2 has in-plane magnetic anisotropy.
[0100] Figure 20 This is a cross-sectional view showing an example of the configuration of an MTJ element according to another variation of the described embodiment. In this variation, with Figure 17 In this configuration example, the lower electrode E3 is offset towards the lower electrode E2. 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 protrude. 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.
[0101] 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 can be omitted, substituted, or modified in various ways without departing from the spirit of the invention. These embodiments or variations thereof are included in the scope or spirit of the invention, as well as in the invention as described in the claims and its equivalents.
[0102] [Symbol Explanation]
[0103] MC: Storage Unit
[0104] WTr: Write transistor
[0105] RTr: Readout transistor
[0106] C1: Conductive layer
[0107] WWL: Write word line
[0108] RWL: Readout Word Line
[0109] WBL: Write Bit Line
[0110] RBL: Readout bit line
[0111] E1: First electrode
[0112] E2: Second electrode
[0113] E3: Third electrode
[0114] 10: MTJ components
[0115] 11: Non-magnetic conductive layer
[0116] 12: First magnetic layer
[0117] 13: Non-magnetic insulating layer
[0118] 14: Second magnetic layer.
Claims
1. A magnetic storage device, comprising: Electrode 1; The second and third electrodes are arranged at a distance in the first direction; A non-magnetic conductive layer electrically connects the second electrode and the third electrode and extends along the first direction; A first magnetic layer is disposed in a second direction intersecting the first direction relative to the non-magnetic conductive layer. The first magnetic layer extends along 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; as well as 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 positioned between the second electrode and the third electrode, at a position where it at least partially overlaps with the second electrode, or at a position where it at least partially overlaps with the third electrode. When viewed from the second direction, the portion of the non-magnetic insulating layer that overlaps with the second region has a thinner film thickness than the portion that overlaps with the first region.
2. A magnetic storage device, comprising: Electrode 1; The second and third electrodes are arranged at a distance in the first direction; A non-magnetic conductive layer electrically connects the second electrode and the third electrode and extends along the first direction; A first magnetic layer is disposed in a second direction intersecting the first direction relative to the non-magnetic conductive layer. The first magnetic layer extends along 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 the magnetization direction is fixed along the second direction; as well as 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 positioned between the second electrode and the third electrode, at a position where it at least partially overlaps with the second electrode, or at a position where it at least partially overlaps 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.
3. A magnetic storage device comprising a first magnetoresistive element and a second magnetoresistive element, wherein... The first magnetoresistive element and the second magnetoresistive element each comprise: Electrode 1; The second and third electrodes are arranged at a distance in the first direction; A non-magnetic conductive layer electrically connects the second electrode and the third electrode and extends along the first direction; A first magnetic layer is disposed in a second direction intersecting the first direction relative to the non-magnetic conductive layer. The first magnetic layer extends along 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; as well as 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 positioned between the second electrode and the third electrode, at a position where it at least partially overlaps with the second electrode, or at a position where it at least partially overlaps with the third electrode. The first magnetoresistive element and the second magnetoresistive element are disposed in a plane including a third direction that intersects the first direction and the second direction. 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 storage device according to claim 2 or 3, wherein The non-magnetic insulating layer is not provided in the second direction of the second region.
5. The magnetic storage device according to any one of claims 1 to 3, wherein When viewed from the second direction, the portion of the non-magnetic insulating layer that overlaps with the second region has more crystal defects than the portion that overlaps with the first region.
6. The magnetic storage device according to 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. The magnetic storage device according to any one of claims 1 to 3, wherein The first direction is the direction in which the write current flows through the non-magnetic conductive layer or the first magnetic layer. 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. The magnetic storage device according to any one of claims 1 to 3, wherein The first magnetic layer includes a plurality of the second regions. The plurality of second regions are arranged on both sides of the first region in the first direction.
9. The magnetic storage device according to any one of claims 1 to 3, wherein The first region is characterized by a magnetization direction that varies depending on the direction in which the write current flows through the non-magnetic conductive layer or the first magnetic layer. The second region is one in which the magnetization direction does not change according to the write current.
10. The magnetic storage device according to any one of claims 1 to 3, wherein The second electrode and the third electrode are connected to the two ends of the non-magnetic conductive layer and the first magnetic layer in the first direction. The non-magnetic insulating layer, the second magnetic layer, and the first electrode are disposed in the first direction at the center of the non-magnetic conductive layer and the first magnetic layer.
11. The magnetic storage device according to 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. The magnetic storage device according to any one of claims 1 to 3, comprising: The source wiring is connected to the third electrode; Write the wiring and connect it to the second electrode; as well as Read out the wiring and connect it to the first electrode; The first direction is a direction that is inclined relative to the source wiring, the write wiring, and the read wiring.
13. The magnetic storage device according to any one of claims 1 to 3, further comprising: A third magnetic layer is disposed between the second electrode and the non-magnetic conductive layer; and A fourth magnetic layer is disposed between the third electrode and the non-magnetic conductive layer.
14. The magnetic storage device according to claim 13, wherein The third and fourth magnetic layers have magnetization directions opposite to those in the second region, and the magnetization directions do not change according to the write current flowing through the non-magnetic conductive layer or the first magnetic layer.
15. The magnetic memory according to claim 1 or 2, wherein the magnetic memory comprises at least a first magnetoresistive element and a second magnetoresistive element. The first magnetoresistive element and the second magnetoresistive element each comprise: a first electrode, a second electrode, a third electrode, a non-magnetic conductive layer, a first magnetic layer, a non-magnetic insulating layer, and a second magnetic layer. The first magnetoresistive element and the second magnetoresistive element are disposed in a plane including a third direction that intersects the first direction and the second direction.
16. The magnetic storage device according to claim 15, wherein When viewed from the second direction, the non-magnetic conductive layer and the first magnetic layer are separated for each magnetoresistive element.