Magnetic element and magnetic recording array

Abstract

The magnetic element (100) of the present embodiment includes a wiring layer (10) extending in a first direction (x) and containing a ferromagnetic substance, and a non-magnetic layer (20) stacked in a second direction (z) with respect to the wiring layer. The wiring layer has a side surface (11) inclined with respect to the second direction on a cut surface orthogonal to the first direction. The side surface has one or more bending points (B1) at which the inclination angle with respect to the second direction is discontinuous. The inclination angle (θ1) of a first inclined surface (11A) farther from the non-magnetic layer is smaller than the inclination angle (θ2) of a second inclined surface (11B) closer to the non-magnetic layer across a first bending point farther from the non-magnetic layer among the bending points.

Description

Technical Field

[0001] The present invention relates to a magnetic element and a magnetic recording array. This application claims priority based on Japanese Patent Application No. 2019-126005 filed on July 5, 2019, the contents of which are incorporated herein by reference. Background Art

[0002] Next-generation nonvolatile memories, which are replacing flash memory, which has reached its limit in terms of miniaturization, are attracting much attention. For example, MRAM (Magnetoresistive Random Access Memory), ReRAM (Resistive Random Access Memory), and PCRAM (Phase Change Random Access Memory) are known as next-generation nonvolatile memories.

[0003] MRAM uses changes in resistance caused by changes in magnetization direction to record data. Data recording is performed by each of the magnetoresistive change elements that make up the MRAM. For example, Patent Document 1 describes a magnetoresistive change element (domain wall moving element) that can record multi-valued data by moving the magnetic domain walls within the data recording layer.

[0004] For example, Patent Document 2 describes a magnetoresistive element (SOT element) that rewrites data (reverses magnetization) using spin-orbit torque. In Patent Document 2, the side surfaces of a stacked body SB1 stacked on a metal-containing layer 21 are tilted to prevent an increase in the power consumption of the SOT element.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 5397384

[0008] Patent Document 2: Japanese Patent No. 6275806 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] The domain wall moving element records data at the location of the domain wall in a multi-valued or analog manner. To achieve this, the domain wall preferably moves slowly. This is because, if the domain wall is sensitive to external forces, even a slight application of force can significantly alter the data. Increasing the resistance-area product (RA) of the domain wall moving element slows the movement of the domain wall. This can be achieved, for example, by increasing the thickness of the non-magnetic layer.

[0011] On the other hand, if the non-magnetic layer is thick, if the side of the stack is tilted by milling or the like, as described in Patent Document 2, the portion that becomes the shadow of the non-magnetic layer increases, and the width of the portion that becomes the hem becomes wider. If the width of the portion that becomes the hem of the stack becomes wider, the cross-sectional area of ​​the wiring layer where the domain walls move becomes larger. Magnetic domain walls move by magnetization reversal, and the minimum current density required for magnetization reversal is called the critical current density. If the cross-sectional area of ​​the wiring layer where the domain walls move increases, the amount of current required to ensure the criticality increases, the operating current of the domain wall moving element becomes larger, and as a result, power consumption increases.

[0012] This problem isn't limited to domain wall displacement devices. For example, in the SOT device described in Patent Document 2, the bottom edge of the conductive layer, which casts a shadow over the nonmagnetic layer, widens during milling. A larger cross-sectional area of ​​the conductive layer reduces the current density in the conductive layer for the same current, resulting in a higher operating current for the SOT device.

[0013] The present invention has been made in view of the above-mentioned problems, and provides a magnetic element and a magnetic recording array that can reduce the operating current.

[0014] Technical means to solve the problem

[0015] (1) A magnetic element of the first type comprises: a wiring layer extending in a first direction and comprising a ferromagnetic material; and a non-magnetic layer stacked in a second direction relative to the wiring layer, wherein the wiring layer has a side surface inclined relative to the second direction on a cutting surface perpendicular to the first direction, and the side surface has one or more bending points with discontinuous inclination angles relative to the second direction, and the inclination angle of the first inclined surface far from the non-magnetic layer is smaller than the inclination angle of the second inclined surface close to the non-magnetic layer, separated by a first bending point among the bending points that is located farthest from the non-magnetic layer.

[0016] (2) The wiring layer of the magnetic element of the above aspect may include a first ferromagnetic layer, a magnetic recording layer, and a nonmagnetic underlayer in this order from a position close to the nonmagnetic layer.

[0017] (3) The wiring layer of the magnetic element of the above aspect may include a first ferromagnetic layer and a conductive layer in this order from a position close to the nonmagnetic layer.

[0018] (4) In the magnetic element of the above aspect, the first inflection point may be located on a side surface of the first ferromagnetic layer.

[0019] (5) In the magnetic element of the above aspect, the first inflection point may be located on a side surface of the magnetic recording layer.

[0020] (6) In the magnetic element of the above aspect, the first bending point may be located on a side surface of the base layer.

[0021] (7) In the magnetic element of the above aspect, the first bending point may be located on a side surface of the conductive layer.

[0022] (8) In the magnetic element of the above aspect, the first inflection point may be located at a boundary between the first ferromagnetic layer and the magnetic recording layer.

[0023] (9) In the magnetic element of the above aspect, the first inflection point may be located at a boundary between the magnetic recording layer and the underlayer.

[0024] (10) In the magnetic element of the above aspect, the first inflection point may be located at a boundary between the first ferromagnetic layer and the conductive layer.

[0025] (11) It may also be that, in a third direction perpendicular to the first direction and the second direction of a cutting surface perpendicular to the first direction of the magnetic element in the above-mentioned manner, the distance between the end of the non-magnetic layer and the first bending point is longer than the distance between the end of the wiring layer and the first bending point.

[0026] (12) It may also be that, on a cutting surface perpendicular to the first direction of the magnetic element in the above-mentioned manner, the distance between the end of the non-magnetic layer and the first bending point in the second direction is longer than the distance between the end of the wiring layer and the first bending point in the second direction.

[0027] (13) It may also be that in the magnetic element of the above-mentioned method, a second bending point among the bending points, which is located farther away from the non-magnetic layer than the first bending point, and the inclination angle of the second inclined surface located away from the non-magnetic layer is greater than the inclination angle of the third inclined surface located close to the non-magnetic layer.

[0028] (14) It may also be that in a third direction perpendicular to the first direction and the second direction of the cutting surface perpendicular to the first direction of the magnetic element in the above-mentioned manner, the distance between the first bending point and the second bending point is longer than the distance between the end of the wiring layer and the first bending point.

[0029] (15) It may also be that, on a cutting surface perpendicular to the first direction of the magnetic element in the above-mentioned manner, the distance between the first bending point and the second bending point in the second direction is longer than the distance between the end of the wiring layer and the first bending point in the second direction.

[0030] (16) In the magnetic element of the above aspect, the first bending point may extend along the first direction.

[0031] (17) In the magnetic element of the above embodiment, the resistance-area product (RA) of the nonmagnetic layer may be 1×10 4 Ωμm 2 above.

[0032] (18) In the magnetic element of the above aspect, an insulating layer may be further provided on a surface of the wiring layer opposite to the non-magnetic layer.

[0033] (19) In the magnetic element of the above aspect, an insulating layer may be further provided on a surface of the wiring layer opposite to the non-magnetic layer.

[0034] (20) A second embodiment of a magnetic recording array comprises a plurality of magnetic elements of the above embodiment.

[0035] Effects of the Invention

[0036] The magnetic element and magnetic recording array of the above-described method can reduce the operating current. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural diagram of the magnetic recording array of the first embodiment.

[0038] Figure 2 This is a cross-sectional view of a characteristic portion of the magnetic recording array according to the first embodiment.

[0039] Figure 3 It is a cross-sectional view taken along the xz plane of the magnetic domain wall moving element according to the first embodiment.

[0040] Figure 4 It is a cross-sectional view of the magnetic domain wall moving element according to the first embodiment, taken along the yz plane.

[0041] Figure 5 It is a top view of the magnetic domain wall moving element according to the first embodiment.

[0042] Figure 6 It is a cross-sectional view showing a part of the manufacturing process of the magnetic domain wall moving element of the first embodiment.

[0043] Figure 7 It is a cross-sectional view showing a part of the manufacturing process of the magnetic domain wall moving element of the first embodiment.

[0044] Figure 8 It is a cross-sectional view of the magnetic domain wall moving element of the comparative example taken along the yz plane.

[0045] Figure 9 It is a cross-sectional view of the magnetic domain wall moving element according to the first modification example taken along the yz plane.

[0046] Figure 10It is a cross-sectional view of the magnetic domain wall moving element according to the second modification example taken along the yz plane.

[0047] Figure 11 It is a cross-sectional view taken along the yz plane of the magnetic domain wall moving element according to the third modification.

[0048] Figure 12 It is a cross-sectional view of the magnetic domain wall moving element according to the fourth modification example taken along the yz plane.

[0049] Figure 13 It is a cross-sectional view of the magnetic domain wall moving element according to the second embodiment, taken along the yz plane.

[0050] Figure 14 It is a cross-sectional view taken along the xz plane of the magnetic domain wall moving element according to the third embodiment.

[0051] Figure 15 It is a cross-sectional view of the magnetic domain wall moving element according to the third embodiment, taken along the yz plane. DETAILED DESCRIPTION

[0052] The present embodiment will be described in detail below with reference to the accompanying drawings as appropriate. To facilitate understanding of the features of the present invention, the accompanying drawings used in the following description may sometimes be partially enlarged, and the dimensional ratios of the various components may differ from actual dimensions. The materials, dimensions, and other aspects described below are merely examples, and the present invention is not limited to these. Appropriate variations may be made within the scope of achieving the effects of the present invention.

[0053] First, the directions are defined. The +x direction, -x direction, +y direction, and -y direction are related to the substrate Sub (see Figure 2 ) is a direction roughly parallel to one side of the magnetic domain wall moving element 10. The +x direction is the direction in which the wiring layer 10 described later extends, and is the direction from the first conductive layer 40 described later toward the second conductive layer 50. The -x direction is the direction opposite to the +x direction. When the +x direction and the -x direction are not distinguished, it is simply referred to as the "x direction". The x direction is an example of a first direction. The +y direction is a direction orthogonal to the x direction. The -y direction is the direction opposite to the +y direction. When the +y direction and the -y direction are not distinguished, it is simply referred to as the "y direction". The y direction is an example of a third direction. The +z direction is the direction from the substrate Sub described later toward the magnetic domain wall moving element 100. The -z direction is the direction opposite to the +z direction. When the +z direction and the -z direction are not distinguished, it is simply referred to as the "z direction". The z direction is an example of a second direction. In addition, in this specification, "extending along the x direction" means, for example, that the dimension in the x direction is larger than the smallest dimension among the dimensions in the x direction, the y direction, and the z direction. The same applies to extending in other directions.

[0054] [First embodiment]

[0055] Figure 1 This is a structural diagram of a magnetic recording array according to the first embodiment. The magnetic recording array 200 includes multiple magnetic domain wall moving elements 100, multiple first wirings Wp1 to Wpn, multiple second wirings Cm1 to Cmn, multiple third wirings Rp1 to Rpn, multiple first switching elements 110, multiple second switching elements 120, and multiple third switching elements 130. The magnetic recording array 200 can be used in, for example, magnetic memories, product-sum calculators, and neuromorphic devices. The magnetic domain wall moving elements 100 are an example of magnetic elements.

[0056] <First wiring, second wiring, third wiring>

[0057] The first wirings Wp1 to Wpn are write wirings that electrically connect a power source to one or more magnetic domain wall moving elements 100. The power source is connected to one end of the magnetic recording array 200 during use.

[0058] The second wirings Cm1 to Cmn are common wirings. Common wirings can be used for both writing and reading data. The second wirings Cm1 to Cmn electrically connect a reference potential to one or more magnetic domain wall moving elements 100. The reference potential is, for example, ground. The second wirings Cm1 to Cmn can be provided to each of the multiple magnetic domain wall moving elements 100 or across multiple magnetic domain wall moving elements 100.

[0059] The third wirings Rp1 to Rpn are readout wirings that electrically connect a power source to one or more magnetic domain wall moving elements 100. The power source is connected to one end of the magnetic recording array 200 during use.

[0060] <First Switching Element, Second Switching Element, Third Switching Element>

[0061] Figure 1 The first switching element 110, the second switching element 120, and the third switching element 130 shown are connected to each of the plurality of magnetic domain wall moving elements 100. The substance that connects the switching element to the magnetic domain wall moving element 100 is called a semiconductor device. The first switching element 110 is connected between each of the magnetic domain wall moving elements 100 and the first wirings Wp1 to Wpn. The second switching element 120 is connected between each of the magnetic domain wall moving elements 100 and the second wirings Cm1 to Cmn. The third switching element 130 is connected between each of the magnetic domain wall moving elements 100 and the third wirings Rp1 to Rpn.

[0062] When the first switching element 110 and the second switching element 120 are turned on, a write current flows between the first wirings Wp1 to Wpn and the second wirings Cm1 to Cmn connected to a given magnetic domain wall moving element 100. When the first switching element 110 and the third switching element 130 are turned on, a read current flows between the second wirings Cm1 to Cmn and the third wirings Rp1 to Rpn connected to a given magnetic domain wall moving element 100.

[0063] The first switching element 110, the second switching element 120, and the third switching element 130 are elements that control the flow of current. For example, the first switching element 110, the second switching element 120, and the third switching element 130 may be a transistor, an element utilizing a phase change in a crystal layer such as an OTS (Ovonic Threshold Switch), an element utilizing a change in energy band structure such as a Metal-Insulator Transition (MIT) switch, an element utilizing a breakdown voltage such as a Zener diode or an avalanche diode, or an element whose conductivity changes with a change in atomic position.

[0064] The first switching element 110, the second switching element 120, and the third switching element 130 can all be shared by the magnetic domain wall movement element 100 connected to the same wiring. For example, if the first switching element 110 is shared, one first switching element 110 is provided upstream of the first wirings Wp1 to Wpn. For example, if the second switching element 120 is shared, one second switching element 120 is provided upstream of the second wirings Cm1 to Cmn. For example, if the third switching element 130 is shared, one third switching element 130 is provided upstream of the third wirings Rp1 to Rpn.

[0065] Figure 2 It is a cross-sectional view of a characteristic portion of the magnetic recording array 200 according to the first embodiment. Figure 2 It will Figure 1 A cross section of one magnetic domain wall moving element 100 is cut along an xz plane passing through the center of the width in the y direction of the wiring layer 10 .

[0066] Figure 2 The first switching element 110 and the second switching element 120 shown are transistors Tr. Transistor Tr includes a gate G, a gate insulating film GI, and a source region S and a drain region D formed on a substrate Sub. The substrate Sub is, for example, a semiconductor substrate. The third switching element 130 is electrically connected to an electrode E, for example, in the depth direction (-y direction) of the drawing.

[0067] Each of the transistors Tr is electrically connected to the magnetic domain wall moving element 100 via a connection wire Cw. The connection wire Cw is made of a conductive material and extends in the z direction. The connection wire Cw is, for example, a through-hole wire formed in an opening of the insulating layer 90.

[0068] The magnetic domain wall moving element 100 and the transistor Tr are electrically separated by the insulating layer 90 in addition to the connection wiring Cw. The insulating layer 90 is an insulating layer that insulates the wiring between the multilayer wiring and between the elements. The insulating layer 90 is, for example, silicon oxide (SiO x ), silicon nitride (SiNx), silicon carbide (SiC), chromium nitride, silicon carbonitride (SiCN), silicon oxynitride (SiON), aluminum oxide (Al2O3), zirconium oxide (ZrO x ) etc. The insulating layer 90 is located, for example, on the opposite side of the wiring layer 10 to be described later and the non-magnetic layer 20 .

[0069] "Magnetic domain wall moving element"

[0070] Figure 3 The cross-sectional view is obtained by cutting the magnetic domain wall moving element 100 along the xz plane passing through the center of the wiring layer 10 in the y direction. The magnetic domain wall moving element 100 includes the wiring layer 10, the nonmagnetic layer 20, the second ferromagnetic layer 30, the first conductive layer 40, and the second conductive layer 50.

[0071] Wiring layer

[0072] The wiring layer 10 extends in the x-direction and includes a portion that can conduct electricity. For example, when viewed from above in the z-direction, the wiring layer 10 is rectangular with the major axis in the x-direction and the minor axis in the y-direction. The wiring layer 10 faces the second ferromagnetic layer 30 across the non-magnetic layer 20. For example, the wiring layer 10 spans the first conductive layer 40 and the second conductive layer 50 and is stacked on the insulating layer 90. Current flows along the wiring layer 10 through the insulating layer 90. The wiring layer 10 comprises a ferromagnetic material and has a ferromagnetic layer on the non-magnetic layer 20 side.

[0073] The wiring layer 10 includes, for example, a first ferromagnetic layer 12, a magnetic recording layer 14, and an underlayer 16. The first ferromagnetic layer 12, the magnetic recording layer 14, and the underlayer 16 are located adjacent to the nonmagnetic layer 20 in this order.

[0074] The magnetic recording layer 14 is a layer that can magnetically record information by changing the magnetic state inside. The magnetic recording layer 14 has a first magnetic domain 14A and a second magnetic domain 14B inside. The magnetization M of the first magnetic domain 14A is 14A and the magnetization M of the second magnetic domain 14B 14BFor example, the first magnetic domain 14A and the second magnetic domain 14B are oriented in opposite directions. The boundary between the first magnetic domain 14A and the second magnetic domain 14B is a magnetic domain wall 17. The magnetic recording layer 14 may have a magnetic domain wall 17 inside. The magnetization M of the magnetic recording layer 14, for example, the first magnetic domain 14A 14A Oriented in the +z direction, the magnetization M of the second magnetic domain 14B 14B Oriented along the -z direction.

[0075] The following description uses an example in which the magnetization is oriented in the z-axis direction. However, the magnetization of the magnetic recording layer 14, the first ferromagnetic layer 12, and the second ferromagnetic layer 30 can also be oriented in the x-axis direction or in any direction within the xy plane. When the magnetization is oriented in the z-direction, the power consumption and heat generation during operation of the magnetic domain wall moving element 100 are reduced compared to when the magnetization is oriented in the xy plane. Furthermore, when the magnetization is oriented in the z-direction, the movement amplitude of the magnetic domain wall 17 when a pulse current of the same intensity is applied is smaller than when the magnetization is oriented in the xy plane. On the other hand, when the magnetization is oriented in any direction within the xy plane, the magnetoresistance variation amplitude (MR ratio) of the magnetic domain wall moving element 100 is larger than when the magnetization is oriented in the z-direction.

[0076] If the magnetic domain wall 17 moves, the ratio of the first magnetic domain 14A to the second magnetic domain 14B changes. The magnetic domain wall 17 moves by flowing a write current in the x direction of the magnetic recording layer 14. For example, when a write current (e.g., a current pulse) is applied in the +x direction of the magnetic recording layer 14, electrons flow in the -x direction opposite to the current, and thus the magnetic domain wall 17 moves in the -x direction. When the current flows from the first magnetic domain 14A to the second magnetic domain 14B, the spin-polarized electrons in the second magnetic domain 14B cause the magnetization M of the first magnetic domain 14A to change. 14A Magnetization reversal. The magnetization M of the first magnetic domain 14A 14A The magnetization is reversed, and the magnetic domain wall 17 moves in the −x direction.

[0077] The magnetic recording layer 14 is composed of a magnetic material. The magnetic recording layer 14 preferably contains at least one element selected from Co, Ni, Pt, Pd, Gd, Tb, Mn, Ge, and Ga. Examples of materials for the magnetic recording layer 14 include: a stacked film of Co and Ni, a stacked film of Co and Pt, a stacked film of Co and Pd, a MnGa-based material, a GdCo-based material, and a TbCo-based material. Ferrimagnetic materials such as MnGa-based materials, GdCo-based materials, and TbCo-based materials have low saturation magnetization, and the threshold current required to move the magnetic domain wall 17 becomes smaller. In addition, the coercive force of the stacked film of Co and Ni, the stacked film of Co and Pt, and the stacked film of Co and Pd is large, and the movement speed of the magnetic domain wall 17 becomes slower.

[0078] The first ferromagnetic layer 12 is positioned between the magnetic recording layer 14 and the non-magnetic layer 20. The first ferromagnetic layer 12 is magnetically coupled to the magnetic recording layer 14. By magnetically coupling with the magnetic recording layer 14, the first ferromagnetic layer 12 reflects the magnetic state of the magnetic recording layer 14. When the first ferromagnetic layer 12 and the magnetic recording layer 14 are ferromagnetically coupled, the magnetic state of the first ferromagnetic layer 12 is the same as the magnetic state of the magnetic recording layer 14. When the first ferromagnetic layer 12 and the magnetic recording layer 14 are antiferromagnetically coupled, the magnetic state of the first ferromagnetic layer 12 is opposite to the magnetic state of the magnetic recording layer 14.

[0079] The first ferromagnetic layer 12 faces the second ferromagnetic layer 30, causing a change in magnetoresistance. The difference in the relative angle between the magnetization of the second ferromagnetic layer 30 and the magnetization of the first ferromagnetic layer 12 causes a change in the resistance value of the magnetic domain wall moving element 100. The first ferromagnetic layer 12 reflects the magnetic state of the magnetic recording layer 14 and is divided into a first magnetic domain 12A and a second magnetic domain 12B. The magnetization M of the first magnetic domain 12A is 12A For example, the magnetization M of the second ferromagnetic layer 30 30 In the same direction (parallel), the magnetization M of the second magnetic domain 12B 12B For example, the magnetization M of the second ferromagnetic layer 30 30 In the opposite direction (antiparallel), when viewed from above in the z direction, if the area of ​​the first magnetic domain 12A in the portion overlapping the second ferromagnetic layer 30 increases, the resistance value of the magnetic domain wall moving element 100 decreases. Conversely, when viewed from above in the z direction, if the area of ​​the second magnetic domain 12B in the portion overlapping the second ferromagnetic layer 30 increases, the resistance value of the magnetic domain wall moving element 100 increases.

[0080] When a predetermined external force is applied, the magnetization of the first ferromagnetic layer 12 is more easily oriented than the magnetization of the second ferromagnetic layer 30. The predetermined external force may be, for example, an external force applied to the magnetization by an external magnetic field or a spin-polarized current. The first ferromagnetic layer 12 is sometimes referred to as a magnetization free layer.

[0081] The first ferromagnetic layer 12 comprises a ferromagnetic material. For example, the first ferromagnetic layer 12 comprises a material that easily produces a coherent tunneling effect with the second ferromagnetic layer 30. For example, the first ferromagnetic layer 12 comprises a metal selected from the group consisting of Cr, Mn, Co, Fe, and Ni, an alloy comprising one or more of these metals, and an alloy comprising these metals and at least one of B, C, and N. Examples of the first ferromagnetic layer 12 include Co-Fe, Co-Fe-B, and Ni-Fe.

[0082] The first ferromagnetic layer 12 may also be, for example, a Heusler alloy. The Heusler alloy is a semimetal with a high spin polarization rate. The Heusler alloy is an intermetallic compound with a chemical composition of XYZ or X2YZ, where X is a transition metal element or a noble metal element of the Co, Fe, Ni, or Cu group on the periodic table, Y is a transition metal of the Mn, V, Cr, or Ti group or an element type of X, and Z is a typical element of group III to group V. Examples of Heusler alloys include Co2FeSi, Co2FeGe, Co2FeGa, Co2MnSi, Co2Mn 1-a Fe a Al b Si 1-b 、Co2FeGe 1-c Ga c wait.

[0083] The base layer 16 is located on the opposite side of the magnetic recording layer 14 from the first ferromagnetic layer 12. The base layer 16 is made of a non-magnetic material. The base layer 16 is a layer for defining the crystal structure of the magnetic recording layer 14. By defining the base layer 16 in a defined structure, the crystallinity of the magnetic recording layer 14 is improved, and the orientation of the magnetization of the magnetic recording layer 14 is improved. The defined structure also depends on the crystal structure of the magnetic recording layer 14, and may be, for example, amorphous, a (001)-oriented NaCl structure, a (002)-oriented perovskite structure represented by the composition formula of ABO3, a (001)-oriented tetragonal structure, or a cubic structure.

[0084] Underlayer 16 is a conductor or an insulator. Underlayer 16 is preferably a conductor. If underlayer 16 is a conductor, its thickness is preferably thinner than that of magnetic recording layer 14. If underlayer 16 is thick, most of the current flowing through wiring layer 10 flows through underlayer 16, increasing the amount of current required to move magnetic domain walls 17. Underlayer 16 includes, for example, Ta, Ru, Pt, Ir, Rh, W, Pd, Cu, Au, or Cu.

[0085] The wiring layer 10 may not include the first ferromagnetic layer 12. In this case, the resistance value of the magnetic domain wall moving element 100 changes due to the difference in the relative angle between the magnetization of the magnetic recording layer 14 and the magnetization of the second ferromagnetic layer 30. In this case, the magnetic recording layer 14 is preferably composed of a material with a high coercive force that facilitates coherent tunneling with the second ferromagnetic layer 30 and slows the movement speed of the magnetic domain wall 17. Furthermore, the wiring layer 10 may not include the base layer 16.

[0086] Figure 4 The magnetic domain wall moving element 100 is Figure 3Cross-sectional view taken along plane AA in FIG. Side surface 11 of wiring layer 10 is inclined in the y-direction relative to the z-direction. Side surface 11 has one or more inflection points. An inflection point is a point where the inclination angle relative to the z-direction is discontinuous. Discontinuity means that the inclination angle of the line connecting side surface 11 is not constant or does not change continuously.

[0087] Specifically, the bending point is confirmed by the following procedure. First, a cross-section of the magnetic domain wall moving element 100 is photographed using a transmission electron microscope (TEM). The transmission electron microscope image is taken at a magnification that can fully confirm the shape of the side 11, depending on the size of the magnetic domain wall moving element 100. Next, the brightness of the portion of the insulating layer 90 and the brightness of the portion of the magnetic recording layer 14 are extracted, and the intermediate value is defined. Then, the image photographed with the intermediate value as the threshold is binarized. Next, the inclination angle of the line connecting the side 11 in the binary image is calculated at 10 points that divide the side 11 into 10 equal parts along the y direction. Then, the position of the measurement point and the inclination angle of the measurement point are plotted in a graph, and when the approximate straight line bends in the middle, this point becomes a bending point.

[0088] The inflection point at the position farthest from the nonmagnetic layer 20 is referred to as a first inflection point B1 . Figure 4 The side surface 11 shown has only one inflection point, which is the first inflection point B1. In addition, the inclined surface away from the non-magnetic layer 20 based on the first inflection point B1 is called the first inclined surface 11A, and the inclined surface toward the non-magnetic layer 20 based on the first inflection point B1 is called the second inclined surface 11B. The first inflection point B1 is sandwiched between the first inflection surface 11A and the second inflection surface 11B. Figure 4 In the illustrated magnetic domain wall moving element 100 , the first inflection point B1 is located at the boundary between the magnetic recording layer 14 and the base layer 16 .

[0089] The first inclined surface 11A and the second inclined surface 11B may be flat or curved. When the first inclined surface 11A and the second inclined surface 11B are flat, they are straight lines in the yz plane. When the first inclined surface 11A and the second inclined surface 11B are curved, they are curved lines in the yz plane. Figure 4 In FIG, the case where the first inclined surface 11A and the second inclined surface 11B are curved surfaces is exemplified.

[0090] The inclination angle θ1 of the first inclined surface 11A with respect to the z direction is smaller than the inclination angle θ2 of the second inclined surface 11B with respect to the z direction. Here, when the first inclined surface 11A and the second inclined surface 11B are curved surfaces, the inclination angles θ1 and θ2 in the z direction of the line connecting the first bending point B1 are defined.

[0091] Furthermore, the distance L1 in the y direction between the first inflection point B1 and the end e1 of the non-magnetic layer 20 is, for example, longer than the distance L2 in the y direction between the first inflection point B1 and the end e2 of the wiring layer 10. Furthermore, the height H1 in the z direction between the first inflection point B1 and the end e1 of the non-magnetic layer 20 is, for example, longer than the height H2 in the z direction between the first inflection point B1 and the end e2 of the wiring layer 10. The z-direction heights H1 and H2 are the distances from the ends e1 and e2 below to a perpendicular to the xy plane passing through the first inflection point B1.

[0092] in addition, Figure 5 : is a top view of the magnetic domain wall moving element 100. The first bending point B1 extends in the x direction. The first bending point B1 extends in the x direction means that even if the wiring layer 10 is cut in the yz plane at any position in the x direction, there is still the first bending point B1. In addition, the first bending point B1 is continuous in the x direction. The first bending point B1 is continuous in the x direction means that in the top view from the z direction, the first bending point B1 can be confirmed as a continuous straight line or curve. In addition, Figure 5 In the example, the first bending point B1 can be identified as a straight line along the x-direction. When the positions of the first bending point B1 in the y-direction and the z-direction are constant, the first bending point B1 is identified as a straight line along the x-direction.

[0093] "Non-magnetic layer"

[0094] The non-magnetic layer 20 is located between the wiring layer 10 and the second ferromagnetic layer 30. The non-magnetic layer 20 is laminated on one surface of the wiring layer 10.

[0095] The non-magnetic layer 20 is composed of, for example, a non-magnetic insulator, semiconductor, or metal. Examples of non-magnetic insulators include Al2O3, SiO2, MgO, MgAl2O4, and materials in which some of the Al, Si, and Mg are replaced with Zn, Be, or the like. These materials have large band gaps and excellent insulating properties. When the non-magnetic layer 20 is composed of a non-magnetic insulator, it serves as a tunnel barrier layer. Examples of non-magnetic metals include Cu, Au, and Ag. Examples of non-magnetic semiconductors include Si, Ge, CuInSe2, CuGaSe2, and Cu(In, Ga)Se2.

[0096] The thickness of the non-magnetic layer 20 is, for example, (2nm) or more, preferably (2.5nm) or more, more preferably (3nm) or more. If the thickness of the non-magnetic layer 20 is thick, the formation of the inflection point becomes easy. In addition, if the thickness of the non-magnetic layer 20 is thick, the resistance area product (RA) of the magnetic domain wall moving element 100 becomes large. The resistance area product (RA) of the magnetic domain wall moving element 100 is, for example, 1×10 3 Ωμm2 More than, preferably 1×10 4 Ωμm 2 More than 1×10 5 Ωμm 2 The resistance-area product (RA) of the domain wall moving element 100 is represented by the product of the element resistance of one domain wall moving element 100 and the element cross-sectional area of ​​the domain wall moving element 100 (the area of ​​the surface obtained by cutting the nonmagnetic layer 20 along the xy plane).

[0097] "Second ferromagnetic layer"

[0098] The second ferromagnetic layer 30 faces the nonmagnetic layer 20. The second ferromagnetic layer 30 has a magnetization M oriented in one direction. 30 The magnetization M of the second ferromagnetic layer 30 is 30 When a predetermined external force is applied, the orientation direction is less likely to change than the magnetization of the first ferromagnetic layer 12. The predetermined external force may be, for example, an external force applied to the magnetization by an external magnetic field or a spin-polarized current. The second ferromagnetic layer 30 is sometimes referred to as a magnetization pinned layer or a magnetization reference layer.

[0099] The second ferromagnetic layer 30 is made of the same material as that of the first ferromagnetic layer 12 .

[0100] The thickness of the second ferromagnetic layer 30 is preferably 1.5 nm or less, and more preferably 1.0 nm or less, when the easy magnetization axis of the second ferromagnetic layer 30 is oriented in the z-direction (perpendicular magnetization film). Reducing the thickness of the second ferromagnetic layer 30 imparts perpendicular magnetic anisotropy (interfacial perpendicular magnetic anisotropy) to the second ferromagnetic layer 30 at the interface between the second ferromagnetic layer 30 and another layer (non-magnetic layer 20), making it easier for the magnetization of the second ferromagnetic layer 30 to align in the z-direction.

[0101] When the easy magnetization axis of the second ferromagnetic layer 30 is oriented in the z-direction (perpendicular magnetization film), the second ferromagnetic layer 30 is preferably formed by stacking a ferromagnetic material selected from Co, Fe, and Ni and a non-magnetic material selected from Pt, Pd, Ru, and Rh. More preferably, an intermediate layer selected from Ir and Ru is inserted at any position in the stack. When the ferromagnetic and non-magnetic materials are stacked, perpendicular magnetic anisotropy can be imparted, and the insertion of the intermediate layer facilitates the magnetization of the second ferromagnetic layer 30 to be oriented in the z-direction.

[0102] An antiferromagnetic layer may also be provided on the surface of the second ferromagnetic layer 30 opposite the nonmagnetic layer 20 via a spacer layer. The second ferromagnetic layer 30, the spacer layer, and the antiferromagnetic layer form a synthetic antiferromagnetic structure (SAF structure). The synthetic antiferromagnetic structure is composed of two magnetic layers sandwiching a nonmagnetic layer. The antiferromagnetic coupling between the second ferromagnetic layer 30 and the antiferromagnetic layer increases the coercive force of the second ferromagnetic layer 30 compared to a case without the antiferromagnetic layer. The antiferromagnetic layer is, for example, IrMn, PtMn, or the like. The spacer layer may contain, for example, at least one selected from Ru, Ir, and Rh.

[0103] "First conductive layer and second ferromagnetic layer"

[0104] The first conductive layer 40 and the second conductive layer 50 are connected to the wiring layer 10. The first conductive layer 40 and the second conductive layer 50 are, for example, connecting portions connecting the wiring Cw and the wiring layer 10. The first conductive layer 40 is connected to, for example, a first end portion of the wiring layer 10, and the second conductive layer 50 is connected to, for example, a second end portion of the wiring layer 10. When the magnetic domain wall moving element 100 does not include the first conductive layer 40 and the second conductive layer 50, the connecting wiring Cw and the wiring layer 10 are directly connected.

[0105] The first conductive layer 40 and the second conductive layer 50 include, for example, a magnetic material. The direction of magnetization of the first conductive layer 40 is different from the direction of magnetization of the second conductive layer 50. The first conductive layer 40 and the second conductive layer 50 pin the magnetization of the magnetic recording layer 14 near the first conductive layer 40 and the second conductive layer 50. By pinning the magnetization of the magnetic recording layer 14 near the first conductive layer 40 and the magnetization of the magnetic recording layer 14 near the second conductive layer 50 to different directions, magnetic domain walls 17 are generated in the magnetic recording layer 14.

[0106] The first conductive layer 40 and the second conductive layer 50 include, for example, a metal selected from Cr, Mn, Co, Fe, and Ni, an alloy containing one or more of these metals, or an alloy containing these metals and at least one of B, C, and N. The first conductive layer 40 and the second conductive layer 50 are, for example, Co-Fe, Co-Fe-B, or Ni-Fe. Furthermore, the first conductive layer 40 and the second conductive layer 50 may also have a synthetic antiferromagnetic structure (SAF structure). A synthetic antiferromagnetic structure is composed of two magnetic layers sandwiching a nonmagnetic layer. The two magnetic layers are fixedly magnetized, and the directions of the fixed magnetizations are opposite.

[0107] The magnetization direction of each layer of the domain wall moving element 100 can be confirmed by measuring a magnetization curve, for example. The magnetization curve can be measured using, for example, the MOKE (Magneto Optical Kerr Effect). MOKE measurement utilizes the magneto-optical effect (magnetic Kerr effect), which causes linearly polarized light to be incident on the object being measured and rotates the polarization direction.

[0108] Next, a method for manufacturing the magnetic recording array 200 will be described. The magnetic recording array 200 is formed by laminating each layer and processing a portion of each layer into a predetermined shape. The lamination of each layer can be performed using sputtering, chemical vapor deposition (CVD), electron beam evaporation (EB), atomic laser deposition, etc. The processing of each layer can be performed using photolithography, etc.

[0109] First, impurities are doped at predetermined locations of the substrate Sub to form a source region S and a drain region D. Next, a gate insulating film GI and a gate G are formed between the source region S and the drain region D. The source region S, the drain region D, the gate insulating film GI, and the gate G form a transistor Tr.

[0110] Next, an insulating layer 90 is formed to cover the transistor Tr. Furthermore, an opening is formed in the insulating layer 90 and filled with a conductor to form the connection wiring Cw. The first wiring Wp and the second wiring Cm are formed by laminating the insulating layer 90 to a predetermined thickness, forming a groove in the insulating layer 90, and filling the groove with a conductor.

[0111] The first conductive layer 40 and the second conductive layer 50 can be formed, for example, by sequentially stacking a ferromagnetic layer, a nonmagnetic layer, and a ferromagnetic layer on one side of the insulating layer 90 and the connection wiring Cw, and removing portions other than those to be the first conductive layer 40 and the second conductive layer 50. The removed portions are filled with, for example, the insulating layer 90.

[0112] Figure 6 1 is a cross-sectional view showing a part of the manufacturing process of the magnetic domain wall moving element 100 according to the first embodiment. Figure 6 As shown, an underlayer 86, a ferromagnetic layer 84, a ferromagnetic layer 82, a nonmagnetic layer 83, and a ferromagnetic layer 85 are stacked in this order on an insulating layer 90 sandwiching the first conductive layer 40 and the second conductive layer 50. After processing, the underlayer 86 becomes the underlayer 16, the ferromagnetic layer 84 becomes the magnetic recording layer 14, the ferromagnetic layer 82 becomes the first ferromagnetic layer 12, the nonmagnetic layer 83 becomes the nonmagnetic layer 20, and the ferromagnetic layer 85 becomes the second ferromagnetic layer 30. Next, a resist R is formed on a portion of the ferromagnetic layer 85. The resist R is formed, for example, so as to extend in the x-direction according to the shape of the wiring layer 10 to be formed.

[0113] Next, the laminate is processed into a predetermined shape through the resist R. The processing of the laminate is carried out in two steps. Figure 6 As shown, the first processing is performed by irradiating the ion beam 87 from a direction inclined relative to the xy plane. Irradiating the ion beam 87 from a direction inclined relative to the xy plane is for example to prevent a portion of the ferromagnetic layer 85 from reaching the side of the non-magnetic layer 83, thereby preventing the processed second ferromagnetic layer 30 and the wiring layer 10 from short-circuiting. The area that becomes the shadow of the resist R is difficult to mill, and the side surface 81 of the wiring layer 80 is inclined relative to the z direction (see Figure 7 ).

[0114] Furthermore, if the thickness of the nonmagnetic layer 83 is increased to increase the resistance-area product (RA), the height position of the resist R relative to the insulating layer 90 is raised by that amount, and the area cast by the shadow of the resist R increases. If the area cast by the shadow of the resist R increases, the bottom edge of the wiring layer 80 expands in the y direction.

[0115] Figure 7 1 is a cross-sectional view showing a part of the manufacturing process of the magnetic domain wall moving element 100 according to the first embodiment. Figure 7 As shown, the second processing of the laminate is performed. Figure 7 As shown in FIG. 1 , the second processing is to irradiate the lower portion of the wiring layer 80 extending in the y direction with an ion beam 88. The incident angle of the ion beam 88 relative to the xy plane (the inclination angle relative to the z direction) is smaller than that of the first ion beam 87. For example, the ion beam 88 is irradiated approximately perpendicularly to the xy plane. The ion beam 88 removes a portion of the lower portion of the wiring layer 80. As a result, a Figure 4 The magnetic domain wall moving element 100 shown in FIG. A second inclined surface 11B is formed by the first processing, and a first inclined surface 11A is inclined by the second processing. The boundary between the first inclined surface 11A and the second inclined surface 11B is a first inflection point B1.

[0116] According to the magnetic domain wall moving element 100 of the first embodiment, the amount of current required when writing data to the magnetic domain wall moving element 100 can be reduced.

[0117] Figure 8 This is a cross-sectional view of the domain wall moving element 101 of the comparative example on the yz plane. The domain wall moving element 101 of the comparative example is different from the domain wall moving element 100 of the first embodiment in that the side surface 13 of the wiring layer 15 does not have an inflection point. The domain wall moving element 101 of the comparative example is different from the domain wall moving element 100 of the first embodiment in that the side surface 13 of the wiring layer 15 does not have an inflection point. Figure 7 The shape shown is equal. The side surface 13 of the wiring layer 15 does not have a bending point, so it extends downward in the y direction. Compared with the wiring layer 10 of the first embodiment, the area of ​​the wiring layer 15 is increased by the amount of the region R1. The region R1 is Figure 7 The second processing corresponds to the part removed.

[0118] When writing data to the domain wall moving element 100, current is passed along the x-direction of the wiring layer 10. The current flowing along the x-direction of the wiring layer 10 displaces the position of the magnetic domain wall 17, allowing data to be written to the domain wall moving element 100. The magnetic domain wall 17 is moved by magnetization reversal of the magnetic recording layer 14. The magnetization is reversed when the current flowing through the wiring layer 10 exceeds the reversal current density. The reversal current density of the domain wall moving element 100 of the first embodiment and the domain wall moving element 101 of the comparative example are equal. When reversing the magnetization of the magnetic recording layer 14, the minimum value of the current flowing through the wiring layers 10 and 15 is the value obtained by multiplying the reversal current density by the cross-sectional area of ​​the wiring layers 10 and 15. The domain wall moving element 100 of the first embodiment can reduce the amount of current flowing through the wiring layer 10 by the amount of region R1 compared to the domain wall moving element 101 of the comparative example 1.

[0119] The domain wall moving elements 100 are often integrated and used as magnetic memories. If the current required to write data to each domain wall moving element 100 increases, the power consumption of the magnetic memory increases. Even by reducing the current flowing in region R1 alone, the power consumption of a single domain wall moving element 100 can be reduced by approximately 5%. A magnetic memory that integrates multiple domain wall phase elements 100 can significantly reduce the power consumption of the entire magnetic memory even by reducing the current flowing in region R1 alone.

[0120] Furthermore, if the first bending point B1 is positioned at the boundary between the magnetic recording layer 14 and the base layer 16, the probability of failure of the magnetic domain wall moving element 100 can be reduced, thereby improving the yield rate during manufacturing. An example of a failure of the magnetic domain wall moving element 100 is a short circuit between the first ferromagnetic layer 12 and the second ferromagnetic layer 30. One of the main causes of a short circuit is the adhesion of conductive material to the side of the non-magnetic layer 20. Conductive material often adheres during the second processing of the laminate. For example, by irradiating the conductive layer with an ion beam 88, conductive material scatters and adheres to the side of the non-magnetic layer 20. The base layer 16 is farther away from the non-magnetic layer 20 than the magnetic recording layer 14 and the base layer 16. Therefore, it is less likely that the scattered material during the processing of the base layer 16 will adhere to the side of the non-magnetic layer 20.

[0121] Furthermore, by setting the first inflection point B1 at the boundary between the magnetic recording layer 14 and the base layer 16, local concentration of the magnetic field can be suppressed. The inflection point is a corner formed on the side surface 11. The magnetic field tends to concentrate at the corner. The magnetic field affects the magnetization state of the magnetic layer. The magnetization state of the magnetic layer affects, for example, the magnetoresistance change rate (MR ratio) of the magnetic domain wall moving element 100 and the movement of the magnetic domain wall 17. The base layer 16 is a non-magnetic material, and if a inflection point exists at the interface between the base layer 16 and the magnetic recording layer 14, local concentration of the magnetic field can be suppressed.

[0122] In addition, by setting the position of the first inflection point B1 at the boundary between the magnetic recording layer 14 and the base layer 16, the magnetization disorder of the magnetic recording layer 14 and the first ferromagnetic layer 12 can be suppressed. Magnetization is strongly affected by the interface. The side surface 11 changes its inclination angle with the inflection point as the boundary. When the inflection point is located on the side surface of the magnetic recording layer 14 or the first ferromagnetic layer 12, the magnetization state near it becomes disordered as the inflection angle of the inclined surface changes, and the stability of the data is reduced. The base layer 16 is a non-magnetic material. If there is a inflection point at the interface between the base layer 16 and the magnetic recording layer 14, the magnetization disorder can be suppressed.

[0123] Furthermore, by positioning the first inflection point B1 at the boundary between the magnetic recording layer 14 and the base layer 16, the magnetization stability of the magnetic recording layer 14 and the first ferromagnetic layer 12 can be improved, thereby enhancing data stability. Pinning sites are formed on the sides of the magnetic recording layer 14 and the first ferromagnetic layer 12 during processing. These pinning sites maintain the magnetization in a predetermined direction. For example, these pinning sites are mixed layers formed during processing. When the magnetization is maintained in a predetermined direction, even when unexpected external forces are applied, magnetization reversal does not occur, enabling long-term, stable data retention.

[0124] Furthermore, by positioning the first inflection point B1 at the boundary between the magnetic recording layer 14 and the base layer 16, the reversal current density of the magnetic domain wall moving element 100 can be reduced. Near the first inflection point B1, material mixing may occur during processing, causing some of the magnetic elements contained in the magnetic recording layer 14 to be incorporated into the base layer 16. The magnetic elements contained in the base layer 16 act as spin scattering factors, and the spin-orbit interaction strongly acts on the base layer 16. This spin-orbit interaction causes the spin Hall effect, generating a spin current in a direction (z-direction) perpendicular to the direction of current flow. This spin current injects spins from the base layer 16 into the magnetic recording layer 14, imparting a spin-orbit torque to the magnetization of the magnetic recording layer 14. This spin-orbit torque assists the magnetization reversal of the magnetic recording layer 14 and the first ferromagnetic layer 12, thereby reducing the reversal current density of the magnetic domain wall moving element 100.

[0125] Furthermore, by making the distance L1 between the first inflection point B1 and the end e1 of the non-magnetic layer 20 longer than the distance L2 between the first inflection point B1 and the end e2 of the wiring layer 10, the probability of failure of the magnetic domain wall moving element 100 can be reduced, and the amount of current required for data writing can be reduced. A longer distance L1 makes it less likely that scattered debris during processing will adhere to the side surfaces of the non-magnetic layer 20. Furthermore, increasing the area of ​​the removed region R1 shortens the distance L2. Increasing the area of ​​region R1 reduces the amount of current flowing through the wiring layer 10 by the amount of removed region R1.

[0126] If the distance L1 between the first inflection point B1 and the end e1 of the non-magnetic layer 20 is longer than the distance L2 between the first inflection point B1 and the end e2 of the wiring layer 10, the magnetization can be maintained more stably. The side surfaces of the magnetic layer (the first ferromagnetic layer 12 and the magnetic recording layer 14) can serve as pinning points. The wider the area where the magnetization is fixed by the pinning point, the higher the stability of the magnetization, and the more stable the data can be maintained. The area where the pinning point is formed depends on the size of the surface area of ​​the magnetic layer exposed during processing. If the distance L1 is longer than the distance L2, the area of ​​the pinning point formed in the magnetic layer becomes larger.

[0127] Furthermore, if the height H1 between the first inflection point B1 and the end e1 of the non-magnetic layer 20 is greater than the height H2 between the first inflection point B1 and the end e2 of the wiring layer 10, the probability of failure of the magnetic domain wall moving element 100 can be reduced. If the height H1 is increased, scattered debris during processing is less likely to adhere to the side surfaces of the non-magnetic layer 20.

[0128] Furthermore, by making the height H1 of the first inflection point B1 and the end e1 of the non-magnetic layer 20 longer than the height H2 of the first inflection point B1 and the end e2 of the wiring layer 10, the effects of magnetic noise on the magnetic layers (first ferromagnetic layer 12 and magnetic recording layer 14) can be reduced. The inflection point occurs at the corner of the side surface 11. Magnetic fields tend to concentrate at the corners, and the difference in shape around the corners causes magnetization disturbance, generating magnetic noise. Magnetic noise affects the magnetization state of the magnetic layer. The magnetization state of the magnetic layer affects, for example, the magnetoresistance change rate (MR ratio) of the domain wall moving element 100 and the movement of the magnetic domain walls 17. By making height H1 higher than height H2, the amount of magnetic material (magnetization) contained in the range from the bottom surface to height H2 becomes relatively smaller, thus suppressing magnetization disturbance.

[0129] An example of the magnetic recording array 200 and the magnetic domain wall moving element 100 according to the first embodiment has been described in detail. However, the magnetic recording array 200 and the magnetic domain wall moving element 100 according to the first embodiment can be variously modified and changed within the scope of the present invention.

[0130] (First Modification)

[0131] Figure 9 This is a cross-sectional view taken along the yz plane of a domain wall moving element 100A according to a first modification. The domain wall moving element 100A differs from the domain wall moving element 100 in that the first inflection point B1 is located on the side surface of the base layer 16. Components identical to those of the domain wall moving element 100 are denoted by the same reference numerals, and their descriptions are omitted.

[0132] The domain wall moving element 100A of the first modified example can reduce the amount of current required for data writing. Furthermore, the location of the first inflection point B1 on the side of the base layer 16 can suppress the adhesion of scattered matter to the nonmagnetic layer 20, reducing the probability of failure of the domain wall moving element 100A. Furthermore, the base layer 16 is nonmagnetic, which prevents localized magnetic field concentration at the inflection point and reduces magnetization disturbances in the magnetic recording layer 14 and the first ferromagnetic layer 12.

[0133] If the first bending point B1 is located on the side of the base layer 16, the reversal current density of the magnetic domain wall moving element 100A can be reduced. Near the bending point, the symmetry of the crystal structure is broken. This broken symmetry of the crystal structure generates an internal field within the base layer 16, causing the spin-orbit interaction to strongly act on the base layer 16. The spin-orbit interaction causes the spin Hall effect, generating a spin current in a direction (z direction) perpendicular to the direction of current flow. The spin current injects spins from the base layer 16 into the magnetic recording layer 14, imparting a spin-orbit torque to the magnetization of the magnetic recording layer 14. The spin-orbit torque assists the magnetization reversal of the magnetic recording layer 14 and the first ferromagnetic layer 12, thereby reducing the reversal current density of the magnetic domain wall moving element 100A.

[0134] (Second Modification)

[0135] Figure 10 This is a cross-sectional view taken along the yz plane of a second modified example of a domain wall moving element 100B. The domain wall moving element 100B differs from the domain wall moving element 100 in that the first inflection point B1 is located on the side of the magnetic recording layer 14. Components identical to those of the domain wall moving element 100 are denoted by the same reference numerals, and their descriptions are omitted.

[0136] The domain wall moving element 100B of the second modified example can reduce the amount of current required for data writing. Furthermore, if the first inflection point B1 is located on the side of the magnetic recording layer 14, the movement speed of the domain wall 17 can be reduced. The area near the inflection point becomes a pinning point due to the influence of mixing, making it difficult for the domain wall 17 to move. When the amplitude of the domain wall 17's movement relative to the external force decreases, the domain wall moving element 100B can select multiple magnetization states, enabling more accurate data recording.

[0137] Furthermore, if the first inflection point B1 is located on the side of the base layer 16, magnetic elements may be mixed with the base layer 16 during processing. As mentioned above, magnetic elements act as spin scattering factors. When spins are scattered, the spin-orbit interaction is enhanced, and the efficiency of generating spin current relative to electric current increases.

[0138] Furthermore, if the amount of magnetic metal added is excessively increased, the generated spin current may be scattered by the added magnetic metal, resulting in a decrease in the spin current. The molar ratio of the added magnetic metal is preferably sufficiently smaller than the total molar ratio of the elements that constitute the spin-orbit torque distribution. The molar ratio of the added magnetic metal is preferably 3% or less of the total. The proportion of the added magnetic metal can be controlled by varying the position of the inflection point.

[0139] (Third Modification)

[0140] Figure 11 This is a cross-sectional view taken along the yz plane of a domain wall moving element 100C according to a third variation. The domain wall moving element 100C differs from the domain wall moving element 100 in that the first inflection point B1 is located at the boundary between the magnetic recording layer 14 and the first ferromagnetic layer 12. Components identical to those in the domain wall moving element 100 are denoted by the same reference numerals, and their descriptions are omitted.

[0141] The domain wall moving element 100C of the third modification can reduce the current required for data writing. In addition, since the first inflection point B1 is located at the boundary between the magnetic recording layer 14 and the first ferromagnetic layer 12, the magnetization disturbance of the magnetic recording layer 14 and the first ferromagnetic layer 12 can be suppressed.

[0142] In addition, by locating the first bending point B1 at the boundary between the magnetic recording layer 14 and the first ferromagnetic layer 12, it is possible to suppress the occurrence of differences in the orientation direction of the magnetization within the plane of the magnetic recording layer 14. Magnetization is easily affected by the interface. The magnetization near the side 11 is affected by the side 11, for example, tilted from the z direction to the y direction. If the first bending point B1 is located at the boundary between the magnetic recording layer 14 and the first ferromagnetic layer 12, the side of the magnetic recording layer 14 belongs to the first inclined surface 11A. The inclination angle θ1 of the first inclined surface 11A with respect to the z direction is smaller than the inclination angle θ2 of the second inclined surface 11B with respect to the z direction. By orienting the magnetization along the first inclined surface 11A, the difference in the orientation direction of the magnetization between the center of the y direction of the magnetic recording layer 14 and the vicinity of the first inclined surface 11A can be reduced.

[0143] For example, the inclination angle of magnetization relative to the z-direction decreases as it moves toward the center of the magnetic recording layer 14 in the y-direction. The region required to eliminate the inclination of magnetization relative to the z-direction is called a relaxation region. If the inclination angle of the side surface of the magnetic recording layer 14 is large, the width of the relaxation region in the y-direction becomes wider, and the relaxation region intrudes into the region overlapping with the second ferromagnetic layer 30 in the z-direction. If the relaxation region intrudes into the region overlapping with the second ferromagnetic layer 30 in the z-direction, the magnetoresistance change rate (MR ratio) of the magnetic domain wall moving element becomes smaller. In the magnetic domain wall moving element 100C, the first inflection point B1 is located at the boundary between the magnetic recording layer 14 and the first ferromagnetic layer 12. The inclination angle of the side surface of the magnetic recording layer 14 relative to the z-direction is small, and therefore the magnetoresistance change rate (MR ratio) is large.

[0144] (Fourth Modification)

[0145] Figure 12 This is a cross-sectional view taken along the yz plane of a magnetic domain wall moving element 100D according to a fourth modification. The magnetic domain wall moving element 100D differs from the magnetic domain wall moving element 100 in that the first inflection point B1 is located on the side surface of the first ferromagnetic layer 12. Components identical to those of the magnetic domain wall moving element 100 are denoted by the same reference numerals, and their descriptions are omitted.

[0146] The magnetic domain wall moving element 100D of the fourth modification can reduce the amount of current required for data writing. Furthermore, by locating the first inflection point B1 on the side of the first ferromagnetic layer 12, the inclination angle of the side surfaces of the first ferromagnetic layer 12 and the magnetic recording layer 14 relative to the z-direction can be reduced, thereby increasing the magnetoresistance ratio (MR ratio).

[0147] In addition, if the first inflection point B1 is located on the side surface of the first ferromagnetic layer 12 , the area of ​​the removed region R1 can be increased, and the amount of current flowing in the wiring layer 10 can be further reduced.

[0148] [Second embodiment]

[0149] Figure 13 2 is a cross-sectional view taken along the yz plane of the magnetic domain wall moving element 102 according to the second embodiment. The magnetic domain wall moving element 102 differs from the magnetic domain wall moving element 100 in that the side surface 11 has a second inflection point B2.

[0150] The side surface 11 has two bending points. The bending point at the farthest position from the non-magnetic layer 20 is called the first bending point B1, and the bending point at the farthest position from the non-magnetic layer 20 after the first bending point B1 is called the second bending point B2. In addition, the inclined surface away from the non-magnetic layer 20 side with the first bending point B1 as the reference is called the first inclined surface 11A, the inclined surface toward the non-magnetic layer 20 with the first bending point B1 as the reference is called the second inclined surface 11B, and the inclined surface toward the non-magnetic layer 20 side with the second bending point B2 as the reference is called the third inclined surface 11C. The second inclined surface 11B is also an inclined surface away from the non-magnetic layer 20 with the second bending point B2 as the reference. Figure 13 In the magnetic domain wall moving element 102 shown, the first bending point B1 is located at the boundary between the magnetic recording layer 14 and the base layer 16 , and the second bending point B2 is located at the boundary between the magnetic recording layer 14 and the first ferromagnetic layer 12 .

[0151] The first inclined surface 11A, the second inclined surface 11B, and the third inclined surface 11C may be flat surfaces or curved surfaces. Figure 13 The case where the first inclined surface 11A, the second inclined surface 11B, and the third inclined surface 11C are curved surfaces is illustrated.

[0152] The inclination angle θ1 of the first inclined surface 11A with respect to the z-direction is smaller than the inclination angle θ2 of the second inclined surface 11B with respect to the z-direction. Furthermore, the inclination angle θ3 of the second inclined surface 11B with respect to the z-direction is larger than the inclination angle θ4 of the third inclined surface 11C with respect to the z-direction. Here, the inclination angle of the second inclined surface 11B with respect to the z-direction is the inclination of the line connecting the first inflection point B1 in comparison with the first inclined surface 11A, and the inclination of the line connecting the second inflection point B2 in comparison with the third inclined surface 11C.

[0153] Furthermore, the distance L3 in the y direction between the first bending point B1 and the second bending point B2 is, for example, longer than the distance L2 in the y direction between the first bending point B1 and the end e2 of the wiring layer 10. Furthermore, the height H3 in the z direction between the first bending point B1 and the second bending point B2 is, for example, longer than the height H2 in the z direction between the first bending point B1 and the end e2 of the wiring layer 10.

[0154] Second inflection point B2 can be formed, for example, by the difference in etching rates of first ferromagnetic layer 12 and magnetic recording layer 14 with respect to ion beams 87 and 88. Alternatively, if second inflection point B2 does not exist at the interface between the layers, it can be formed by performing the processing in multiple steps.

[0155] The magnetic domain wall moving element 102 of the second embodiment can reduce the amount of current required for data writing. Furthermore, the presence of the second inflection point B2 can further separate the first inclined surface 11A from the non-magnetic layer 20, thereby preventing scattered particles from adhering to the side surfaces of the non-magnetic layer 20 during processing of the first inclined surface 11A.

[0156] Furthermore, by performing multiple processing steps to form the inflection point, the probability of defects in the magnetic domain wall moving element 102 can be reduced, and the manufacturing yield can be improved. By performing multiple ion beam processes, scattered matter attached to the side surfaces of the non-magnetic layer 20 during previous processing can be removed again during subsequent processing. Furthermore, by gradually approaching the ion beam irradiation angle perpendicular to the processing surface, the shape of the side surface 11 can be adjusted, and scattered matter attached to the side surfaces of the non-magnetic layer 20 can be removed. By removing scattered matter that can cause short circuits, the probability of defects in the magnetic domain wall moving element 102 can be reduced, and the manufacturing yield can be improved.

[0157] [Third embodiment]

[0158] The magnetic memory according to the third embodiment is different in that the magnetic domain wall moving element is replaced with a SOT element. Figure 14 1 is a cross-sectional view taken along the xz plane of the SOT element 103 according to the third embodiment. The SOT element is an example of a magnetic element.

[0159] The SOT element 103 includes a wiring layer 60, a non-magnetic layer 20, a second ferromagnetic layer 30, a first conductive layer 40, and a second conductive layer 50. The structures of the non-magnetic layer 20, the second ferromagnetic layer 30, the first conductive layer 40, and the second conductive layer 50 are the same as those of the magnetic domain wall moving element of the first embodiment. However, in the case of the SOT element 103, the thickness of the non-magnetic layer 20 is preferably thinner than that of the magnetic domain wall moving element. For example, the thickness of the non-magnetic layer 20 is (2nm) or less.

[0160] The wiring layer 60 includes a first ferromagnetic layer 62 and a conductive layer 64. The first ferromagnetic layer 62 and the conductive layer 64 are located adjacent to the non-magnetic layer 20 in this order.

[0161] The first ferromagnetic layer 62 includes a magnetic material and has a magnetization M 62 The first ferromagnetic layer 62 can be made of the same material as the second ferromagnetic layer 30. Figure 14 , the case where the length of the first ferromagnetic layer 62 in the x direction matches that of the conductive layer 64 is shown. However, the length of the first ferromagnetic layer 62 in the x direction may be shorter than that of the conductive layer 64 .

[0162] The conductive layer 64 is sometimes called a spin-orbit torque wiring. The conductive layer 64 generates a spin current by the spin Hall effect when current flows, and injects spin into the first ferromagnetic layer 62. For example, the conductive layer 64 gives the first ferromagnetic layer 62 a magnetization M 62 The magnetization M of the first ferromagnetic layer 62 is made as high as possible. 62 The magnetization M of the first ferromagnetic layer 62 is reversed. 62 The magnetization is reversed by the spin-orbit torque (SOT).

[0163] The conductive layer 64 includes any one of a metal, an alloy, an intermetallic compound, a metal boride, a metal carbide, a metal silicide, and a metal phosphide having a function of generating a spin current by the spin Hall effect when current flows.

[0164] The conductive layer 64, for example, contains a non-magnetic heavy metal as a main element. The main element is the element with the highest proportion among the elements constituting the conductive layer 64. The conductive layer 64 contains, for example, a heavy metal having a specific gravity greater than that of yttrium (Y). Non-magnetic heavy metals have a large atomic number of 39 or greater and have d electrons or f electrons in their outermost shells, thus strongly generating spin-orbit interaction. The spin Hall effect is generated by the spin-orbit interaction, and spins are easily deflected within the conductive layer 64, and spin currents are easily generated. The conductive layer 64 contains, for example, any one selected from Au, Hf, Mo, Pt, W, and Ta.

[0165] Figure 15 The SOT element 103 is Figure 14 The side surface 61 of the wiring layer 60 is inclined in the y direction relative to the z direction. The side surface 61 has one or more inflection points. Figure 14 The side surface 61 shown has one first bending point B1 , but may also have more than two bending points.

[0166] The first inflection point B1 is sandwiched between the first inclined surface 61A and the second inclined surface 61B. The first inclined surface 61A is farther away from the non-magnetic layer 20 than the second inclined surface 61B based on the first inflection point B1. Figure 15 In the illustrated SOT element 103, the first inflection point B1 is located on the side of the conductive layer 64. The first inflection point B1 may also be located on the side of the first ferromagnetic layer 62 or at the boundary between the first ferromagnetic layer 62 and the conductive layer 64. The first inclined surface 61A and the second inclined surface 61B may be flat or curved.

[0167] The inclination angle θ1 of the first inclined surface 61A relative to the z-direction is smaller than the inclination angle θ2 of the second inclined surface 61B relative to the z-direction. The positional relationship between the end e1 of the nonmagnetic layer 20, the end e2 of the wiring layer 60, and the first inflection point B1 is the same as that in the case of the magnetic domain wall moving element.

[0168] In the case of the SOT element 103, the thickness of the non-magnetic layer 20 is thin, and it is difficult to form a bending point using the same method as the magnetic domain wall moving element 100 of the first embodiment. In the case of the SOT element 103, for example, a bending point is produced by forming the wiring layer 60 in two stages. Specifically, first, the first layer is formed to a thickness that becomes the bending point. Then, the first layer is processed, and after it becomes a predetermined shape, the surrounding area is filled with an insulating layer. Next, a second layer is formed on the first layer, and the second layer is processed. The first layer and the second layer are combined to form the wiring layer 60. By forming and processing the film in two stages, the shape of the side surface can be freely designed, and a bending point can be produced.

[0169] When the SOT element 103 has the inflection point B1 in the conductive layer 64, the density of the current flowing through the conductive layer 64 becomes high, and the magnetization M of the first ferromagnetic layer 62 becomes high. 62 In addition, when the SOT element 103 has a bending point B1 in the first ferromagnetic layer 62, the magnetization M near the bending point B1 is 62 The inclination of the magnetization M near the bending point B1 is different from that of the other parts. 62 This becomes the opportunity for magnetization reversal and magnetization reversal proceeds. The magnetization M of the first ferromagnetic layer 62 62 Becomes easier to reverse.

[0170] While preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

[0171] For example, the characteristic structures of the first to third embodiments may be combined. Furthermore, while the example of second inflection point B2 being located at the boundary between magnetic recording layer 14 and first ferromagnetic layer 12 is described, the location of second inflection point B2 is not limited to this. Furthermore, while the examples above illustrate the case of one or two inflection points, the number of inflection points may be greater than two.

[0172] Example

[0173] like Figure 6 and Figure 7As shown, a base layer 86, a ferromagnetic layer 84, a ferromagnetic layer 82, a nonmagnetic layer 83, and a ferromagnetic layer 85 were stacked in this order and irradiated with ion beams 87 and 88 in two separate bursts to produce a magnetic domain wall moving element. The thickness of the nonmagnetic layer 83 was varied to produce various magnetic domain wall moving elements. The nonmagnetic layer 83 was made of MgO. The RA and operating current of the resulting magnetic domain wall moving elements were determined. The results are shown in Table 1.

[0174] Table 1

[0175]

[0176] Comparative Examples 1 and 2, the thickness of the non-magnetic layer is thin, Figure 6 and Figure 7 The method shown is difficult to form an inflection point. In addition, Comparative Examples 1 and 2 have low RA and are not suitable for magnetic domain wall moving elements (for example, in the case of neuromorphic devices).

[0177] While the inflection point can be formed in this embodiment, the difference in inclination angle between the first and second inclined surfaces sandwiching the inflection point is small. Therefore, the effect of reducing the operating current is less than that of embodiments 2 to 5. Furthermore, embodiment 1 has the minimum RA suitable for use in a magnetic domain wall moving element.

[0178] Examples 2 to 4 can form a clear inflection point and can also sufficiently achieve the effect of reducing the operating current. In addition, Examples 2 to 4 have RA suitable for application to a magnetic domain wall moving element.

[0179] In Example 5, a clear inflection point can be formed and the effect of reducing the operating current can be sufficiently obtained. On the other hand, the RA of the magnetic domain wall moving element in Example 5 is large.

[0180] Explanation of symbols

[0181] 10, 15, 60, 80 wiring layers

[0182] 11, 13, 61, 81 side

[0183] 11A, 61A first inclined surface

[0184] 11B, 61B Second inclined surface

[0185] 11C Third inclined surface

[0186] 12,62 First ferromagnetic layer

[0187] 12A, 14A first magnetic domain

[0188] 12B, 14B second magnetic domain

[0189] 14 Magnetic recording layer

[0190] 16, 86 basal layer

[0191] 17 Magnetic domain wall

[0192] 20 Non-magnetic layer

[0193] 30 Second ferromagnetic layer

[0194] 40 first conductive layer

[0195] 50 second conductive layer

[0196] 64 conductive layer

[0197] 82, 84, 85 ferromagnetic layer

[0198] 83 non-magnetic layer

[0199] 87, 88 ion beam

[0200] 90 Insulation layer

[0201] 100, 100A, 100B, 100C, 100D, 101, 102 Magnetic domain wall moving elements

[0202] 110 first switching element

[0203] 120 second switching element

[0204] 130 third switching element

[0205] 200 Magnetic Recording Array

[0206] B1 First bending point

[0207] B2 Second bending point

[0208] e1, e2 ends

[0209] L1, L2, L3 distances.

Claims

1. A magnetic element, wherein: It is a magnetic element with a wiring layer and a non-magnetic layer. The wiring layer extends along the first direction and includes a ferromagnetic material. The non-magnetic layer is stacked along a second direction relative to the wiring layer. The magnetic element is a magnetic domain wall moving element or a SOT element, The wiring layer has a side surface inclined relative to the second direction on a cut surface perpendicular to the first direction, The side surface has one or more bending points with discontinuous inclination angles relative to the second direction, A first inclination point located farthest from the non-magnetic layer among the inflection points is separated from the non-magnetic layer, and the inclination angle of the first inclined surface farther from the non-magnetic layer is smaller than the inclination angle of the second inclined surface closer to the non-magnetic layer. The wiring layer includes a first ferromagnetic layer, a magnetic recording layer, and a nonmagnetic underlayer in order from a position close to the nonmagnetic layer. The first inflection point is located at a boundary between the magnetic recording layer and the base layer.

2. A magnetic element, wherein: It is a magnetic element with a wiring layer and a non-magnetic layer. The wiring layer extends along the first direction and includes a ferromagnetic material. The non-magnetic layer is stacked along a second direction relative to the wiring layer. The magnetic element is a magnetic domain wall moving element or a SOT element, The wiring layer has a side surface inclined relative to the second direction on a cut surface perpendicular to the first direction, The side surface has one or more bending points with discontinuous inclination angles relative to the second direction, A first inclination point located farthest from the non-magnetic layer among the inflection points is separated from the non-magnetic layer, and the inclination angle of the first inclined surface farther from the non-magnetic layer is smaller than the inclination angle of the second inclined surface closer to the non-magnetic layer. The wiring layer includes a first ferromagnetic layer, a magnetic recording layer, and a nonmagnetic underlayer in order from a position close to the nonmagnetic layer. The first inflection point is located on a side surface of the magnetic recording layer.

3. A magnetic element, wherein: It is a magnetic element with a wiring layer and a non-magnetic layer. The wiring layer extends along the first direction and includes a ferromagnetic material. The non-magnetic layer is stacked along a second direction relative to the wiring layer. The magnetic element is a magnetic domain wall moving element or a SOT element, The wiring layer has a side surface inclined relative to the second direction on a cut surface perpendicular to the first direction, The side surface has one or more bending points with discontinuous inclination angles relative to the second direction, A first inclination point located farthest from the non-magnetic layer among the inflection points is separated from the non-magnetic layer, and the inclination angle of the first inclined surface farther from the non-magnetic layer is smaller than the inclination angle of the second inclined surface closer to the non-magnetic layer. The wiring layer includes a first ferromagnetic layer, a magnetic recording layer, and a nonmagnetic underlayer in order from a position close to the nonmagnetic layer. The first inflection point is located at a boundary between the first ferromagnetic layer and the magnetic recording layer.

4. The magnetic element according to any one of claims 1 to 3, wherein In a third direction perpendicular to the first and second directions of a cut surface perpendicular to the first direction, a distance between an end of the nonmagnetic layer and the first bending point is longer than a distance between an end of the wiring layer and the first bending point.

5. The magnetic element according to any one of claims 1 to 3, wherein On a cut plane perpendicular to the first direction, a distance between an end of the nonmagnetic layer and the first bending point in the second direction is longer than a distance between an end of the wiring layer and the first bending point in the second direction.

6. The magnetic element according to any one of claims 1 to 3, wherein The inclination angle of the second inclined surface located away from the nonmagnetic layer is larger than the inclination angle of the third inclined surface located close to the nonmagnetic layer, separated by a second inflection point among the inflection points that is next to the first inflection point and located farther from the nonmagnetic layer.

7. The magnetic element according to claim 6, wherein In a third direction perpendicular to the first and second directions of a cut surface perpendicular to the first direction, a distance between the first bending point and the second bending point is longer than a distance between an end of the wiring layer and the first bending point.

8. The magnetic element according to claim 6, wherein On a cut plane perpendicular to the first direction, a distance between the first bending point and the second bending point in the second direction is longer than a distance between an end portion of the wiring layer and the first bending point in the second direction.

9. The magnetic element according to any one of claims 1 to 3, wherein The first bending point extends along the first direction.

10. The magnetic element according to any one of claims 1 to 3, wherein The resistance area product RA of the nonmagnetic layer is 1×10 4 Ωμm 2 above.

11. The magnetic element according to any one of claims 1 to 3, wherein The thickness of the non-magnetic layer is greater than 2.0 nm.

12. The magnetic element according to any one of claims 1 to 3, wherein The wiring layer further includes an insulating layer on a surface opposite to the non-magnetic layer.

13. A magnetic recording array, wherein: A plurality of magnetic elements according to any one of claims 1 to 12 are provided, wherein the magnetic element further includes a second ferromagnetic layer on the side of the nonmagnetic layer opposite to the wiring layer.

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