Magnetized rotating element, magnetoresistive element and magnetic memory

Abstract

The magnetization rotation element includes a spin-orbit torque wiring and a first ferromagnetic layer connected to the spin-orbit torque wiring. The wiring includes a first layer, a second layer, and a third layer from a side close to the first ferromagnetic layer. The second layer is made of a material having a linear expansion coefficient between the linear expansion coefficient of the material of the first layer and the linear expansion coefficient of the material of the third layer.

Description

Technical Field

[0001] This invention relates to a magnetized rotating element, a magnetoresistive effect element, and a magnetic memory. This application claims priority based on PCT / JP2020 / 042602, filed on November 16, 2020, during the international phase, the contents of which are incorporated herein by reference. Background Technology

[0002] Giant magnetoresistive (GMR) devices, which consist of multilayer films with ferromagnetic and nonmagnetic layers, and tunnel magnetoresistive (TMR) devices, which use insulating layers (tunnel barrier layers) in the nonmagnetic layers, are known as magnetoresistive effect devices. Magnetoresistive effect devices can be applied to magnetic sensors, high-frequency components, magnetic heads, and non-volatile random access memory (MRAM).

[0003] MRAM is a memory element that integrates a magnetoresistive element. MRAM reads and writes data by utilizing the characteristic that the resistance of the magnetoresistive element changes when the mutual magnetization direction of the two ferromagnetic layers sandwiching a non-magnetic layer changes. The magnetization direction of the ferromagnetic layers can be controlled, for example, by a magnetic field generated by an electric current. Alternatively, the magnetization direction of the ferromagnetic layers can be controlled, for example, by a spin-transfer torque (STT) generated by allowing current to flow in the stacking direction of the magnetoresistive element.

[0004] When the magnetization direction of the ferromagnetic layer is rewritten using STT (Simplified Transmission Theorem), current flows in the stacking direction of the magnetoresistive element. The write current becomes the cause of the characteristic degradation of the magnetoresistive element.

[0005] In recent years, methods that allow current to flow without crossing the stacking direction of the magnetoresistive element during writing have attracted attention. One such method utilizes spin-orbit torque (SOT) writing. SOT is induced by spin current generated by spin-orbit interaction or by the Rashba effect at the interface of different materials. The current used to induce SOT within the magnetoresistive element flows in a direction intersecting the stacking direction of the magnetoresistive element. That is, it is not necessary for current to flow in the stacking direction of the magnetoresistive element, which is expected to extend the lifetime of the magnetoresistive element.

[0006] Patent Document 1 describes a magnetoresistive effect element that utilizes spin-orbit torque, in which the spin-orbit torque wiring is set as a laminated film and the laminated interface is increased, thereby making it easy to reverse the magnetization of the ferromagnetic layer.

[0007] Existing technical documents

[0008] Patent documents

[0009] [Patent Document 1] Japanese Patent No. 6426330 Summary of the Invention

[0010] The technical problem that the invention aims to solve

[0011] Spin-orbit torque wiring is prone to heating when a write current is applied. Heating of the spin-orbit torque wiring introduces thermal stress. In cases where the spin-orbit torque wiring consists of multiple layers, strain can sometimes occur due to differences in the expansion rates of the layers. This strain can lead to cracking and delamination of the laminated film.

[0012] The present invention was made in view of the above circumstances, and its object is to provide a magnetized rotating element, a magnetoresistive effect element, and a magnetic memory capable of suppressing the deterioration of spin-orbit torque wiring caused by strain.

[0013] Means for solving technical problems

[0014] To address the aforementioned issues, the present invention provides the following means.

[0015] (1) The magnetized rotating element of the first type has a spin-orbit torque wiring and a first ferromagnetic layer connected to the spin-orbit torque wiring. The spin-orbit torque wiring has a first layer, a second layer and a third layer in sequence from the side close to the first ferromagnetic layer. The linear expansion coefficient of the material constituting the second layer is between the linear expansion coefficient of the material constituting the first layer and the linear expansion coefficient of the material constituting the third layer.

[0016] (2) In the magnetized rotating element described above, the first layer may contain a first element as the main element, the second layer may contain a second element different from the first element as the main element, and the third layer may contain a third element different from the first element and the second element as the main element, wherein the linear expansion coefficient of the second element is between the linear expansion coefficient of the first element and the linear expansion coefficient of the third element.

[0017] (3) In the magnetized rotating element described above, the first layer may contain a first element as the main element, the second layer may contain a second element different from the first element as the main element, and the third layer may contain a third element different from the first and second elements as the main element. The first and third elements are any one of Au, Bi, Hf, Ir, Mo, Pd, Pt, Rh, Ru, Ta, W, Ag, Al, Cu, Ge, and Si, and the second element is any one of Ag, Au, Bi, Co, Cr, Cu, Fe, Ge, Hf, Ir, Mo, Ni, Pd, Pt, Rh, Ru, and Ta.

[0018] (4) In the magnetized rotating element described above, the first element may be any one of Au, Bi, Hf, Ir, Mo, Pd, Pt, Rh, Ru, Ta, and W; the second element may be any one of Ag, Au, Bi, Co, Cr, Cu, Fe, Ge, Hf, Ir, Mo, Ni, Pd, Pt, Rh, Ru, and Ta; and the third element may be any one of Ag, Al, Cu, Ge, and Si.

[0019] (5) In the magnetized rotating element described above, the perimeter of the first layer may be shorter than the perimeters of the second and third layers, and the perimeter of the second layer may be shorter than the perimeter of the third layer.

[0020] (6) In the magnetized rotating element described above, the perimeter of the first layer may be longer than the perimeters of the second and third layers, and the perimeter of the second layer may be longer than the perimeter of the third layer.

[0021] (7) The magnetized rotating element described above may also further include: a fourth layer comprising the same material as the second layer; and a fifth layer comprising the same material as the first or third layer. The fourth layer is located between the fifth layer and the third layer.

[0022] (8) In the magnetized rotating element described above, the thickness of the second layer may be thinner than that of the first layer and the third layer.

[0023] (9) In the magnetized rotating element described above, the second layer may be a continuous film with multiple openings or a layer containing multiple constituent elements distributed in an island-like manner.

[0024] (10) The magnetized rotating element described above may also include: an intermediate layer connected to the spin-orbit torque wiring, and a conductive layer connected to the spin-orbit torque wiring via the intermediate layer, wherein the linear expansion coefficient of the material constituting the intermediate layer is between the linear expansion coefficient of the layer connected to the intermediate layer and the linear expansion coefficient of the conductive layer.

[0025] (11) The magnetoresistive effect element of the second embodiment includes: the magnetized rotating element of the above embodiment; a non-magnetic layer that is in contact with the first ferromagnetic layer of the magnetized rotating element; and a second ferromagnetic layer that, together with the first ferromagnetic layer, sandwiches the non-magnetic layer in the middle.

[0026] (12) The magnetic memory of the third type has multiple magnetoresistive effect elements as described above.

[0027] The effects of the invention

[0028] The magnetized rotating element, magnetoresistive effect element, and magnetic memory of the present invention can suppress the deterioration of spin-orbit torque wiring caused by strain. Attached Figure Description

[0029] Figure 1 This is a circuit diagram of the magnetic array according to the first embodiment.

[0030] Figure 2 This is a cross-sectional view of a characteristic portion of the magnetic array according to the first embodiment.

[0031] Figure 3 This is a cross-sectional view of the magnetoresistive effect element according to the first embodiment.

[0032] Figure 4 This is a top view of the magnetoresistive effect element according to the first embodiment.

[0033] Figure 5 This is a cross-sectional view of the magnetoresistive effect element in the first modified example.

[0034] Figure 6 This is a cross-sectional view of the magnetoresistive effect element in the second variation.

[0035] Figure 7 This is an example of a top view of the second layer of the second variation.

[0036] Figure 8 This is another example of the top view of the second layer of the second variation.

[0037] Figure 9 This is a cross-sectional view of the magnetoresistive effect element in the third variation.

[0038] Figure 10 This is a cross-sectional view of the magnetoresistive effect element in the fourth variation.

[0039] Figure 11 This is a cross-sectional view of the magnetized rotating element in the second embodiment. Detailed Implementation

[0040] Hereinafter, this embodiment will be described in detail with appropriate reference to the accompanying drawings. In the drawings used in the following description, for ease of understanding, some parts of the features are sometimes shown as enlarged for convenience, and the size ratios of each component may differ from the actual dimensions. The materials, dimensions, etc., illustrated in the following description are examples, and the present invention is not limited thereto; appropriate modifications can be made to achieve the effects of the present invention.

[0041] First, the orientation is defined. The substrate Sub (refer to...) will be described later. Figure 2One direction of one side of the conductive layer is designated as the x-direction, and the direction orthogonal to the x-direction is designated as the y-direction. The x-direction, for example, is the direction from the first conductive layer 31 towards the second conductive layer 32. The z-direction is the direction orthogonal to both the x- and y-directions. The z-direction is an example of the stacking direction of the layers. Hereinafter, the +z direction may sometimes be represented as "up" and the -z direction as "down." Up and down are not necessarily consistent with the direction in which gravity is applied.

[0042] In this specification, "extending in the x-direction" means, for example, that the dimension in the x-direction is greater than the smallest dimension among the dimensions in the x, y, and z directions. The same applies when extending in other directions. Furthermore, in this specification, "connection" is not limited to physical connections. For example, it is not limited to the case of two layers in physical contact; it also includes the case of two layers connected by sandwiching another layer in between.

[0043] <First Implementation>

[0044] Figure 1 This is a structural diagram of the magnetic array 200 according to the first embodiment. The magnetic array 200 includes a plurality of magnetoresistive effect elements 100, a plurality of write lines WL, a plurality of common lines CL, a plurality of read lines RL, a plurality of first switching elements Sw1, a plurality of second switching elements Sw2, and a plurality of third switching elements Sw3. The magnetic array 200 can be used, for example, in a magnetic memory.

[0045] The write wiring WL electrically connects the power supply to one or more magnetoresistive elements 100. The common wiring CL is used for both data writing and reading. The common wiring CL electrically connects the reference potential to one or more magnetoresistive elements 100. The reference potential is, for example, ground. The common wiring CL can be located at each of the multiple magnetoresistive elements 100, or it can be distributed across multiple magnetoresistive elements 100. The read wiring RL electrically connects the power supply to one or more magnetoresistive elements 100. The power supply is connected to the magnetic array 200 during use.

[0046] Each magnetoresistive element 100 is connected to a first switching element Sw1, a second switching element Sw2, and a third switching element Sw3, respectively. The first switching element Sw1 is connected between the magnetoresistive element 100 and the write wiring WL. The second switching element Sw2 is connected between the magnetoresistive element 100 and the common wiring CL. The third switching element Sw3 is connected to the read wiring RL, which extends across the multiple magnetoresistive elements 100.

[0047] When the first switching element Sw1 and the second switching element Sw2 are turned on (ON), a write current flows between the write wiring WL and the common wiring CL, which are connected to the specified magnetoresistive effect element 100. Data is written to the specified magnetoresistive effect element 100 by flowing the write current. When the second switching element Sw2 and the third switching element Sw3 are turned on (ON), a read current flows between the common wiring CL and the read wiring RL, which are connected to the specified magnetoresistive effect element 100. Data is read from the specified magnetoresistive effect element 100 by flowing the read current.

[0048] The first switching element Sw1, the second switching element Sw2, and the third switching element Sw3 are elements that control the flow of current. These elements can be, for example, transistors and Ovonic Threshold Switches (OTS) that utilize phase transitions in the crystal layer; metal-insulator transfer (MIT) switches that utilize changes in band structure; Zener diodes and avalanche diodes that utilize breakdown voltage; or elements whose conductivity changes with atomic positions.

[0049] exist Figure 1 In the magnetic array 200 shown, the magnetoresistive effect elements 100 connected with the same wiring share a third switching element Sw3. The third switching element Sw3 can also be provided in each magnetoresistive effect element 100. Alternatively, the third switching element Sw3 can be provided in each magnetoresistive effect element 100, and the first switching element Sw1 or the second switching element Sw2 can be shared among the magnetoresistive effect elements 100 connected with the same wiring.

[0050] Figure 2 This is a cross-sectional view of a characteristic portion of the magnetic array 200 according to the first embodiment. Figure 2 The cross section of the magnetoresistive element 100 is cut by the xz plane, which is the center of the width of the spin-orbit torque wiring 20 described later.

[0051] Figure 2 The first switching element Sw1 and the second switching element Sw2 shown are transistors Tr. The third switching element Sw3 is electrically connected to the readout wiring RL, for example, located at... Figure 2 The y-direction. The transistor Tr is, for example, a field-effect transistor, and has a gate electrode G, a gate insulating film GI, and a source electrode S and a drain electrode D formed on a substrate Sub. The substrate Sub is, for example, a semiconductor substrate.

[0052] Transistor Tr is electrically connected to magnetoresistive element 100 via via wiring V, first conductive layer 31, and second conductive layer 32. Additionally, transistor Tr is connected to write wiring WL or common wiring CL via via wiring V. Via wiring V extends, for example, in the z-direction. Readout wiring RL is connected to stack 10 via electrode E. Via wiring V, electrode E, first conductive layer 31, and second conductive layer 32 contain conductive materials.

[0053] The magnetoresistive element 100 and the transistor Tr are surrounded by an insulating layer In. The insulating layer In is used to insulate between wirings in a multilayer wiring system or between components. The insulating layer In is, for example, silicon oxide (SiO2). x ), silicon nitride (SiN) x Silicon carbide (SiC), chromium nitride, silicon carbonitride (SiCN), silicon oxynitride (SiON), aluminum oxide (Al2O3), zirconium oxide (ZrO2) x Magnesium oxide (MgO), aluminum nitride (AlN), etc.

[0054] Figure 3 This is a cross-sectional view of the magnetoresistive element 100. Figure 3 It is the cross section that cuts the magnetoresistive element 100 by the xz plane, which is the center of the width of the spin-orbit torque wiring 20 in the y direction. Figure 4 This is a top view of the magnetoresistive element 100 viewed from the z-direction.

[0055] The magnetoresistive element 100 includes, for example, a laminate 10, a spin-orbit torque wiring 20, a first conductive layer 31, and a second conductive layer 32. The laminate 10 is in electrical contact with the spin-orbit torque wiring 20. The laminate 10 is also in physical contact with the spin-orbit torque wiring 20. The laminate 10 is stacked on or above the spin-orbit torque wiring 20. Other layers may also be present between the laminate 10 and the spin-orbit torque wiring 20. The first conductive layer 31 and the second conductive layer 32 are connected to the spin-orbit torque wiring 20. Other layers may also be present between each of the first conductive layer 31 and the second conductive layer 32 and the spin-orbit torque wiring 20. Viewed from the z-direction, the first conductive layer 31 and the second conductive layer 32 are positioned to hold the laminate 10.

[0056] The resistance value in the z-direction of the stack 10 is varied by injecting spin into the stack 10 from the spin-orbit torque wiring 20. The magnetoresistive effect element 100 is a magnetic element that utilizes spin-orbit torque (SOT) and is sometimes referred to as a spin-orbit torque type magnetoresistive effect element, a spin-injection type magnetoresistive effect element, or a spin-current magnetoresistive effect element.

[0057] The laminate 10 is connected in the z-direction by the spin-orbit torque wiring 20 and the electrode E (reference). Figure 2Clamping. The laminate 10 is a columnar body. The top view shape of the laminate 10 viewed from the z-direction is, for example, circular, elliptical, or quadrilateral. The side 10s of the laminate 10 is, for example, inclined relative to the z-direction.

[0058] The laminate 10, for example, has a first ferromagnetic layer 1, a second ferromagnetic layer 2, and a nonmagnetic layer 3. The first ferromagnetic layer 1, for example, is in contact with and stacked on a spin-orbit torque wiring 20. Spin is injected into the first ferromagnetic layer 1 from the spin-orbit torque wiring 20. The magnetization of the first ferromagnetic layer 1 is affected by spin-orbit torque (SOT) through the injected spin, and its orientation direction changes. The second ferromagnetic layer 2 is located in the z-direction of the first ferromagnetic layer 1. The first ferromagnetic layer 1 and the second ferromagnetic layer 2 are sandwiched between the nonmagnetic layer 3 in the z-direction.

[0059] The first ferromagnetic layer 1 and the second ferromagnetic layer 2 are each magnetized. The orientation of the magnetization of the second ferromagnetic layer 2 is less likely to change compared to the magnetization of the first ferromagnetic layer 1 when a specified external force is applied. Sometimes the first ferromagnetic layer 1 is referred to as the magnetization-free layer, and the second ferromagnetic layer 2 is referred to as the magnetization-fixed layer or magnetization-reference layer. Figure 3 In the stack 10 shown, the magnetization fixing layer is located on the side away from the substrate Sub and is referred to as the top pin structure. The resistance value of the stack 10 varies depending on the relative angle of magnetization between the first ferromagnetic layer 1 and the second ferromagnetic layer 2, which sandwich the non-magnetic layer 3.

[0060] The first ferromagnetic layer 1 and the second ferromagnetic layer 2 contain ferromagnetic materials. Ferromagnetic materials may be, for example, metals selected from Cr, Mn, Co, Fe, and Ni; alloys containing one or more of these metals; or alloys containing these metals and at least one of the elements selected from B, C, and N. Examples of ferromagnetic materials include Co-Fe, Co-Fe-B, Ni-Fe, Co-Ho alloys, Sm-Fe alloys, Fe-Pt alloys, Co-Pt alloys, and CoCrPt alloys.

[0061] The first ferromagnetic layer 1 and the second ferromagnetic layer 2 may also contain Heussler alloys. Heussler alloys contain intermetallic compounds with a chemical composition of XYZ or X2YZ. X is a transition metal or noble metal element from the Co, Fe, Ni, or Cu group of the periodic table; Y is a transition metal from the Mn, V, Cr, or Ti group, or an element of X; and Z is a typical element from Groups III to V. Examples of Heussler alloys include Co2FeSi, Co2FeGe, Co2FeGa, Co2MnSi, and Co2Mn. 1-a Fe a Al b Si 1-b Co2FeGe 1-c Gac Etc. Heussler alloys exhibit high spin polarization.

[0062] The nonmagnetic layer 3 comprises a nonmagnetic material. When the nonmagnetic layer 3 is an insulator (in the case of a tunneling barrier layer), materials such as Al₂O₃, SiO₂, MgO, and MgAl₂O₄ can be used. Alternatively, materials in which a portion of Al, Si, or Mg is replaced by Zn, Be, etc., can also be used. Among these, MgO and MgAl₂O₄ are materials capable of coherent tunneling, thus enabling efficient spin injection. When the nonmagnetic layer 3 is a metal, materials such as Cu, Au, and Ag can be used. Furthermore, when the nonmagnetic layer 3 is a semiconductor, materials such as Si, Ge, CuInSe₂, CuGaSe₂, and Cu(In,Ga)Se₂ can be used.

[0063] The laminate 10 may also have layers other than the first ferromagnetic layer 1, the second ferromagnetic layer 2, and the nonmagnetic layer 3. For example, a base layer may be provided between the spin-orbit torque wiring 20 and the first ferromagnetic layer 1. The base layer improves the crystallinity of each layer constituting the laminate 10. In addition, for example, a capping layer may be provided on the uppermost surface of the laminate 10.

[0064] Alternatively, the laminate 10 may also have a ferromagnetic layer on the side of the second ferromagnetic layer 2 opposite to the non-magnetic layer 3, separated by a spacer layer. The second ferromagnetic layer 2, the spacer layer, and the ferromagnetic layer constitute a synthetic antiferromagnetic structure (SAF structure). The synthetic antiferromagnetic structure consists of two magnetic layers sandwiching a non-magnetic layer. Due to antiferromagnetic coupling between the second ferromagnetic layer 2 and the ferromagnetic layer, the coercivity of the second ferromagnetic layer 2 is increased compared to the case without a ferromagnetic layer. The ferromagnetic layer may be, for example, IrMn or PtMn. The spacer layer may contain, for example, at least one selected from Ru, Ir, and Rh.

[0065] The spin-orbit torque wiring 20, for example, is longer in the x-direction than in the y-direction when viewed from the z-direction, and extends in the x-direction. The write current flows along the x-direction of the spin-orbit torque wiring 20. At least a portion of the spin-orbit torque wiring 20 sandwiches the first ferromagnetic layer 1 together with the non-magnetic layer 3 in the z-direction.

[0066] The spin-orbit torque wiring 20 generates a spin current through the spin Hall effect when current I flows, injecting spin into the first ferromagnetic layer 1. For example, the spin-orbit torque wiring 20 imparts a spin-orbit torque (SOT) to the magnetization of the first ferromagnetic layer 1 that can only reverse the magnetization of the first ferromagnetic layer 1. The spin Hall effect is the phenomenon of generating a spin current in a direction orthogonal to the direction of current flow based on spin-orbit interaction when current is flowing. The spin Hall effect is similar to the ordinary Hall effect in that the direction of motion (moving) charge (electron) bends the direction of motion (movement). The ordinary Hall effect bends the direction of motion of a charged particle moving in a magnetic field due to the Lorentz force. In contrast, the spin Hall effect bends the direction of spin movement even in the absence of a magnetic field, solely through the movement of electrons (current flow).

[0067] For example, when current flows in the spin-orbit torque wiring 20, the first spin oriented in one direction and the second spin oriented in the opposite direction to the first spin are bent by the spin Hall effect in directions orthogonal to the flow direction of current I. For example, the first spin oriented in the -y direction bends in the +z direction, and the second spin oriented in the +y direction bends in the -z direction.

[0068] In non-magnetic materials (materials that are not ferromagnetic), the number of electrons with first spin and second spin, generated by the spin Hall effect, are equal. That is, the number of electrons with first spin in the +z direction is equal to the number of electrons with second spin in the -z direction. The first and second spins flow in the direction that eliminates spin inhomogeneity. During the movement of the first and second spins in the z-direction, the flow of charge cancels each other out, so the current is zero. Spin currents without accompanying current are specifically called pure spin currents.

[0069] If the flow of electrons with the first spin is expressed as J ↑ The flow of electrons with the second spin can be expressed as J ↓ The spin flow is represented as J S Then J S =J ↑ -J ↓ Definition. Spin flow J S It is generated in the z-direction. The first spin is injected into the first ferromagnetic layer 1 from the spin-orbit torque wiring 20.

[0070] The spin-orbit torque wiring 20 has a first layer 21, a second layer 22, and a third layer 23 sequentially from the side closest to the first ferromagnetic layer 1. The second layer 22 is located between the first layer 21 and the third layer 23. The first layer 21 is located closer to the first ferromagnetic layer 1 than the third layer 23. The first layer 21, the second layer 22, and the third layer 23 are each made of different materials or have different compositions.

[0071] The coefficient of linear expansion of the material constituting the second layer 22 is between the coefficient of linear expansion of the material constituting the first layer 21 and the coefficient of linear expansion of the material constituting the third layer 23. For example, the coefficient of linear expansion of the material constituting the second layer 22 is larger than that of the material constituting the first layer 21 and smaller than that of the material constituting the third layer 23. In this case, the difference between the coefficient of linear expansion of the material constituting the third layer 23 and the coefficient of linear expansion of the material constituting the second layer 22 is preferably less than 70% of the difference between the coefficient of linear expansion of the material constituting the third layer 23 and the coefficient of linear expansion of the material constituting the first layer 21. Alternatively, for example, the coefficient of linear expansion of the material constituting the second layer 22 is smaller than that of the material constituting the first layer 21 and larger than that of the material constituting the third layer 23. In this case, the difference between the linear expansion coefficient of the material constituting the first layer 21 and the linear expansion coefficient of the material constituting the second layer 22 is preferably 70% or less than the difference between the linear expansion coefficient of the material constituting the first layer 21 and the linear expansion coefficient of the material constituting the third layer 23. By satisfying this configuration, the second layer 22 mitigates the thermal stress applied to the first layer 21 and the third layer. The second layer 22 is a stress-relieving layer.

[0072] The coefficient of linear expansion is the proportional change in length with increasing temperature, denoted by α = 1 / ΔT × ΔL / L. Here, α is the coefficient of linear expansion, ΔT is the temperature change, ΔL is the change in length, and L is the length. The coefficient of linear expansion is the coefficient within the operating temperature range, and the length L used as the reference for calculation is the length within that operating temperature range. The operating temperature range is the temperature at which the magnetoresistive element 100 is used most frequently, typically around 25°C when driven at room temperature. Since the coefficient of linear expansion does not have a thickness parameter, it can be determined by forming a relatively thick film of material comprising each layer, to a degree that allows measurement under the same conditions as each layer, and by evaluating the resulting film.

[0073] Furthermore, when the principal elements constituting each layer are specific elements, the linear expansion coefficient of the principal elements can be considered as the linear expansion coefficient of each layer. The principal element is the element with the highest proportion among the elements constituting each layer. When the principal element accounts for more than 50% of the elements constituting each layer, the linear expansion coefficient of the principal elements can be considered as the approximate linear expansion coefficient of each layer. The following table shows the linear expansion coefficients of some elements.

[0074] [Table 1]

[0075]

[0076] For example, when layer 1 contains element 1 as the main element, layer 2 contains element 2 as the main element, and layer 3 contains element 3 as the main element, the linear expansion coefficient of element 2 is preferably between the linear expansion coefficients of element 1 and element 3. For example, the linear expansion coefficient of element 2 is preferably greater than the linear expansion coefficient of element 1 and less than the linear expansion coefficient of element 3. In this case, the difference between the linear expansion coefficient of element 3 and the linear expansion coefficient of element 2 is preferably less than 70% of the difference between the linear expansion coefficient of element 3 and the linear expansion coefficient of element 1, and the difference between the linear expansion coefficient of element 2 and the linear expansion coefficient of element 1 is preferably less than 70% of the difference between the linear expansion coefficient of element 3 and the linear expansion coefficient of element 1. Furthermore, for example, it is preferable that the linear expansion coefficient of element 2 is smaller than the linear expansion coefficient of element 1 and larger than the linear expansion coefficient of element 3. In this case, the difference between the linear expansion coefficient of the first element and the linear expansion coefficient of the second element is preferably less than 70% of the difference between the linear expansion coefficient of the first element and the linear expansion coefficient of the third element, and the difference between the linear expansion coefficient of the second element and the linear expansion coefficient of the third element is preferably less than 70% of the difference between the linear expansion coefficient of the first element and the linear expansion coefficient of the third element.

[0077] Layer 21 may contain, for example, any one or more of Au, Bi, Hf, Ir, Mo, Pd, Pt, Rh, Ru, Ta, W, Ag, Al, Cu, Ge, and Si. The principal element (first element) of Layer 21 may be any one of these elements. Layer 21 may be a single metal, an alloy, an intermetallic compound, or a nitride.

[0078] Compared to layers 22 and 33, layer 21 is located near the first ferromagnetic layer 1, and the spin generated in layer 21 is difficult to diffuse before reaching the first ferromagnetic layer 1. Therefore, layer 21 is preferably a material capable of injecting a large number of spins into the first ferromagnetic layer 1.

[0079] Non-magnetic heavy metals exhibit stronger spin-orbit interactions compared to other metals. Therefore, the first layer 21 preferably comprises a heavy metal with a non-magnetic layer. Heavy metals refer to metals with a specific gravity of yttrium (Y) or higher. Non-magnetic heavy metals are, for example, large non-magnetic metals with an atomic number of 39 or higher and possessing d or f electrons in their outermost shell. The first layer 21, for example, comprises any one or more of Au, Bi, Hf, Ir, Mo, Pd, Pt, Rh, Ru, Ta, and W. The main element (first element) of the first layer 21 is preferably any one of these elements.

[0080] The second layer 22 may contain, for example, one or more of Ag, Au, Bi, Co, Cr, Cu, Fe, Ge, Hf, Ir, Mo, Ni, Pd, Pt, Rh, Ru, and Ta. The main element (second element) of the second layer 22 may be any one of these elements. The second layer 22 may be a single metal, an alloy, an intermetallic compound, or a nitride.

[0081] The third layer 23 may contain, for example, one or more of Au, Bi, Hf, Ir, Mo, Pd, Pt, Rh, Ru, Ta, W, Ag, Al, Cu, Ge, and Si. The main element (third element) of the third layer 23 may be any one of these elements. The third layer 23 may be a pure metal, an alloy, an intermetallic compound, or a nitride.

[0082] The third layer 23 is farther away from the first ferromagnetic layer 1 than the first layer 21 and the second layer 22, and a portion of the spin generated in the third layer 23 diffuses before reaching the first ferromagnetic layer 1. Therefore, the third layer 23 preferably has a function other than generating a large number of spins.

[0083] Light metals exhibit superior electrical and thermal conductivity compared to heavy metals. Therefore, the third layer 23 preferably comprises a light metal. The third layer 23 may contain, for example, one or more of Ag, Al, Cu, Ge, and Si. The main element (third element) of the third layer 23 is preferably any one of these elements.

[0084] The first, second, and third elements are not arbitrarily selected from the aforementioned elements, but rather selected in such a way that the linear expansion coefficient of the second element is between the linear expansion coefficient of the first element and the linear expansion coefficient of the third element.

[0085] For example, the following combinations can be given: setting the first element as W, the second element as Ir, and the third element as Cu; setting the first element as W, the second element as Pt, and the third element as Cu; setting the first element as W, the second element as Ta, and the third element as Cu; and setting the first element as W, the second element as Hf, and the third element as Cu.

[0086] The sidewalls 20s of the spin-orbit torque wiring 20 are inclined, for example, relative to the z-direction. Therefore, the perimeter of the first layer 21 is shorter than that of the second layer 22 and the third layer 23, and the perimeter of the second layer 22 is shorter than that of the third layer 23. The perimeter is the perimeter of the upper surface of each layer away from the substrate Sub. If the width in the z-direction (x-direction) becomes shorter, the current flow between the first conductive layer 31 and the second conductive layer 32 becomes smoother. Because the sidewalls 20s are inclined relative to the z-direction, the surface area of ​​the spin-orbit torque wiring 20 increases, improving heat dissipation.

[0087] Furthermore, when the length of layer 1 (21) in the x-direction is shorter than that of layer 3 (23), according to the relationship α = 1 / ΔT × ΔL / L, the linear expansion coefficient of layer 1 (21) is larger than that of layer 3 (23). When the linear expansion coefficients of each layer satisfy the relationship "linear expansion coefficient of layer 3 (23)" > "linear expansion coefficient of layer 2 (22)" > "linear expansion coefficient of layer 1 (21)", the difference in linear expansion coefficients between the layers can be reduced.

[0088] The thickness of the second layer 22 is, for example, thinner than the thicknesses of the first layer 21 and the third layer 23. This can suppress the diffusion of spins generated in the third layer 23 into the second layer 22.

[0089] Furthermore, the thickness of the first layer 21 is, for example, greater than that of the third layer. Since the first layer 21 is in contact with the first ferromagnetic layer 1, a thicker layer increases the spin implantation efficiency into the first ferromagnetic layer 1.

[0090] In addition to magnetic metals, the layers constituting the spin-orbit torque wiring 20 may also contain topological insulators. Topological insulators are materials whose interior is an insulator or a high-resistivity material, but which exhibit spin polarization on their surface.

[0091] The first conductive layer 31 and the second conductive layer 32 are examples of conductive layers. The first conductive layer 31 and the second conductive layer 32 are each made of a material with excellent conductivity. Examples of the first conductive layer 31 and the second conductive layer 32 are Al, Cu, W, and Cr.

[0092] Next, the manufacturing method of the magnetoresistive element 100 will be described. The magnetoresistive element 100 is formed by a layer stacking process and a processing process of shaping a portion of each layer into a predetermined shape. The layer stacking can be performed using sputtering, chemical vapor deposition (CVD), electron beam evaporation (EB evaporation), atomic laser deposition, etc. The processing of each layer can be performed using photolithography, etc.

[0093] First, impurities are doped at designated locations on the substrate Sub to form the source (S) and drain (D). Next, a gate insulating film (GI) and a gate electrode (G) are formed between the source (S) and drain (D). The source (S), drain (D), gate insulating film (GI), and gate electrode (G) together form the transistor Tr.

[0094] Next, an insulating layer In is formed to cover the transistor Tr. Furthermore, by forming an opening in the insulating layer In and filling the opening with a conductor, a via wiring V, a first conductive layer 31, and a second conductive layer 32 are formed. Write wiring WL and common wiring CL are formed by forming a groove in the insulating layer In after stacking the insulating layer In to a predetermined thickness and filling the groove with a conductor.

[0095] Next, a metal layer, a ferromagnetic layer, a non-magnetic layer, a ferromagnetic layer, and a hard mask layer are sequentially stacked on one side of the insulating layer In, the first conductive layer 31, and the second conductive layer 32. Then, the hard mask layer is processed into a predetermined shape. The predetermined shape is, for example, the outline of the spin-orbit torque wiring 20. Next, the metal layer, ferromagnetic layer, non-magnetic layer, and ferromagnetic layer are processed into the predetermined shape in one pass through the hard mask layer. The metal layer becomes the spin-orbit torque wiring 20 by being processed into the predetermined shape.

[0096] Next, the unwanted portions in the x-direction of the hard mask layer are removed. The hard mask layer forms the shape of the stack 10. Then, via the hard mask layer, the unwanted portions in the x-direction of the stack formed on the spin-orbit torque wiring 20 are removed. The stack 10 is processed into a predetermined shape, becoming the stack 10. The hard mask layer becomes the electrode E. Next, the stack 10 and the area around the spin-orbit torque wiring 20 are filled with an insulating layer In to obtain the magnetoresistive effect element 100.

[0097] The magnetoresistive element 100 of the first embodiment mitigates thermal stress generated in the spin-orbit torque wiring 20 by having the coefficient of linear expansion of the material constituting the second layer 22 between that of the material constituting the first layer 21 and the material constituting the third layer 23. As a result, the magnetoresistive element 100 can suppress interlayer delamination, cracking, etc., caused by heat generated during writing, and can prevent deterioration of the spin-orbit torque wiring 20.

[0098] The above shows an example of the magnetoresistive effect element 100 of the first embodiment, but additions, omissions, substitutions and other changes to the structure can be made without departing from the spirit of the present invention.

[0099] Figure 5 This is a cross-sectional view of the magnetoresistive effect element 101 in the first modified example. Figure 5 It is the xz section at the center of the y-direction of the spin-orbit torque wiring 26. Figure 5 In the middle, to and Figure 3 The same structure is labeled with the same symbol, and the explanation is omitted.

[0100] The spin-orbit torque wiring 26 has a first layer 21, a second layer 22, a third layer 23, a fourth layer 24, and a fifth layer 25. The fourth layer 24 is located between the third layer 23 and the fifth layer 25. Figure 5 The example shown is of a single layer 4 (24) and a single layer 5 (25), but they can also be multiple layers. In the case of multiple layers 4 (24) and 5 (25), the layers 4 (24) and 5 (25) are stacked alternately in the order of layer 4 (24) and layer 5 (25) starting from the side closest to layer 3 (23).

[0101] Layer 4 24 contains the same material as layer 2 22. Layer 4 24 is, for example, made of the same material as layer 2 22. Layer 5 25 contains the same material as layer 1 21 or layer 3 23. Layer 5 25 is, for example, made of the same material as layer 1 21 or layer 3 23.

[0102] The magnetoresistive effect element 101 of the first modification can achieve the same effect as the magnetoresistive effect element 100 of the first embodiment. Furthermore, if the number of layers constituting the spin-orbit torque wiring 25 increases, current is shunted to each layer, thereby reducing the amount of current flowing in each layer. Therefore, heating in each layer can be suppressed, and the generation of thermal stress can be suppressed. In addition, by adding interfaces of different materials to the spin-orbit torque wiring 25, the Lashpa effect is amplified, and the magnetization reversal efficiency of the first ferromagnetic layer 1 can be improved.

[0103] Figure 6 This is a cross-sectional view of the magnetoresistive effect element 102 in the second modified example. Figure 6 It is the xz section at the center of the y-direction of the spin-orbit torque wiring 27. Figure 6 In the middle, to and Figure 3 The same structure is labeled with the same symbol, and the explanation is omitted.

[0104] The spin-orbit torque wiring 27 has a first layer 21, a second layer 22A, and a third layer 23. The second layer 22A differs from the second layer 22 in the first embodiment in that it is not a uniform continuous film, but a continuous film with multiple openings or a layer containing multiple constituent elements distributed in an island-like manner.

[0105] Figure 7 and Figure 8 This is a top view of the magnetoresistive effect element 102 in the second modified example. Figure 7 The second layer 22A shown is an example of a continuous membrane with multiple openings AP. Figure 8 The second layer 22A shown is an example of a layer containing multiple constituent elements EL distributed in an island-like pattern. When the film thickness of the second layer 22A is relatively thin, it may not sometimes become a uniform continuous film. The opening AP and the constituent elements EL are filled with material from the first layer 21 or the third layer 23.

[0106] The magnetoresistive element 102 in the second modification can achieve the same effect as the magnetoresistive element 100 in the first embodiment. Furthermore, the in-plane stress generated between the opening AP and the constituent element EL is mitigated. As a result, deterioration of the spin-orbit torque wiring 26 can be prevented.

[0107] Figure 9 This is a cross-sectional view of the magnetoresistive effect element 103 in the third modified example. Figure 9 It is the xz section at the center of the y-direction of the spin-orbit torque wiring 20. Figure 9 In the middle, to and Figure 3 The same structure is labeled with the same symbol, and the explanation is omitted.

[0108] The magnetoresistive effect element 103 differs from the magnetoresistive effect element 100 of the first embodiment in that it has an intermediate layer 40. The intermediate layer 40 is located between the first conductive layer 31 and the spin-orbit torque wiring 20, and between the second conductive layer 32 and the spin-orbit torque wiring 20. The intermediate layer 40 may also be located only between the first conductive layer 31 and the spin-orbit torque wiring 20 and between the second conductive layer 32 and the spin-orbit torque wiring 20.

[0109] The coefficient of linear expansion of the material constituting the intermediate layer 40 is, for example, between the coefficient of linear expansion of the third layer 23 and the first conductive layer 31 or the second conductive layer 32. When the fourth layer 40 is in contact with the first layer 21, the coefficient of linear expansion of the material constituting the fourth layer 40 is, for example, between the coefficient of linear expansion of the first layer 21 and the first conductive layer 31 or the second conductive layer 32.

[0110] The magnetoresistive effect element 103 of the third modification can achieve the same effect as the magnetoresistive effect element 100 of the first embodiment. In addition, the intermediate layer 40 mitigates the thermal stress difference between the first conductive layer 31 or the second conductive layer 32 and the spin-orbit torque wiring 20, and can suppress delamination at their interface.

[0111] Figure 10 This is a cross-sectional view of the magnetoresistive effect element 104 in the fourth variation. Figure 10 It is the xz section at the center of the y-direction of the spin-orbit torque wiring 28. Figure 10 In the middle, to and Figure 3 The same structure is labeled with the same symbol, and the explanation is omitted.

[0112] Figure 10 The stack 10 shown is a bottom pin structure in which the magnetization fixing layer (second ferromagnetic layer 2) is located near the substrate Sub. The spin-orbit torque wiring 28 is stacked in the order of layer 1 21, layer 22, and layer 3 23, starting from the side closest to the substrate Sub.

[0113] The spin-orbit torque distribution 28 is located, for example, on the laminate 10. The side 28s of the spin-orbit torque distribution 28 is inclined, for example, relative to the z-direction. Therefore, the perimeter of the first layer 21 is longer than the perimeters of the second layer 22 and the third layer 23, and the perimeter of the second layer 22 is longer than the perimeter of the third layer 23. In this case, the length of the first layer 21 in the x-direction is longer than the length of the third layer 23 in the x-direction. Therefore, when the linear expansion coefficients of each layer satisfy the relationship "linear expansion coefficient of the first layer 21" > "linear expansion coefficient of the second layer 22" > "linear expansion coefficient of the third layer 23", the difference in linear expansion coefficients of each layer can be reduced.

[0114] The magnetoresistive effect element 104 in the fourth modification differs only in the positional relationship of its various structures, yet it achieves the same effect as the magnetoresistive effect element 100 in the first embodiment. Furthermore, by tilting the sidewall 28s relative to the z-direction, the surface area of ​​the spin-orbit torque wiring 28 increases, improving heat dissipation.

[0115] <Second Implementation Method>

[0116] Figure 11 This is a cross-sectional view of the magnetized rotating element 105 according to the second embodiment. Figure 1 In this embodiment, the magnetizing rotating element 105 is replaced with the magnetoresistive effect element 100 of the first embodiment.

[0117] The magnetization rotation element 105, for example, incident light onto the first ferromagnetic layer 1 and evaluates the light reflected by the first ferromagnetic layer 1. When the orientation direction of magnetization changes due to the magneto-optical Kerr effect, the deflection state of the reflected light changes. The magnetization rotation element 105 can be used, for example, as an optical element in an image display device that utilizes the difference in the deflection state of light.

[0118] In addition, the magnetized rotating element 105 can also be used independently as an anisotropic magnetic sensor, an optical element utilizing the magnetic Faraday effect, etc.

[0119] The spin-orbit torque wiring 20 of the magnetized rotating element 105 has a first layer 21, a second layer 22 and a third layer 23.

[0120] The magnetized rotating element 105 of the second embodiment removes only the non-magnetic layer 3 and the second ferromagnetic layer 2 from the magnetoresistive effect element 100, and can obtain the same effect as the magnetoresistive effect element 100 of the first embodiment.

[0121] Thus far, preferred embodiments of the present invention have been illustrated based on the first embodiment, the second embodiment, and the modifications, but the present invention is not limited to these embodiments. For example, the characteristic structures in the various embodiments and modifications can also be applied to other embodiments.

[0122] Explanation of symbols:

[0123] 1…First ferromagnetic layer, 2…Second ferromagnetic layer, 3…Nonmagnetic layer, 10…Laminated structure, 20, 26, 27, 28…Spin-orbit torque wiring, 21…First layer, 22, 22A…Second layer, 23…Third layer, 24…Fourth layer, 25…Fifth layer, 31…First conductive layer, 32…Second conductive layer, 40…Fourth layer, 100, 101, 102, 103, 104…Magnetic reluctance element, 105…Magnetic rotating element, 200…Magnetic array, CL…Common wiring, RL…Readout wiring, WL…Write wiring.

Claims

1. A magnetized rotating element, wherein, have: Spin-orbit torque wiring; and The first ferromagnetic layer is connected to the spin-orbit torque distribution line. The spin-orbit torque wiring has three layers, namely a first layer, a second layer, and a third layer, starting from the side closest to the first ferromagnetic layer. The first layer contains the first element as the main element. The second layer contains a second element that is different from the first element, serving as the main element. The third layer contains a third element, different from the first and second elements, as the main element. The first element is W, the second element is any one of Ir, Pt, Ta, and Hf, and the third element is Cu. The coefficient of linear expansion of the material constituting the second layer is between that of the material constituting the first layer and that of the material constituting the third layer.

2. The magnetized rotating element as claimed in claim 1, wherein, The linear expansion coefficient of the second element is between that of the first element and the third element.

3. The magnetized rotating element as described in claim 1 or 2, wherein, The perimeter of the first layer is shorter than the perimeters of the second and third layers. The perimeter of the second layer is shorter than the perimeter of the third layer.

4. The magnetized rotating element as described in claim 1 or 2, wherein, The perimeter of the first layer is longer than the perimeters of the second and third layers. The perimeter of the second layer is longer than that of the third layer.

5. The magnetized rotating element as described in claim 1 or 2, wherein, It also has: A fourth layer comprising the same material as the second layer; and A fifth layer comprising the same material as the first or third layer. The fourth layer is located between the fifth layer and the third layer.

6. The magnetized rotating element as claimed in claim 1 or 2, wherein, The second layer is thinner than the first and third layers.

7. The magnetized rotating element as claimed in claim 1 or 2, wherein, The second layer is a continuous membrane with multiple openings or a layer containing multiple constituent elements distributed in an island-like pattern.

8. The magnetized rotating element as claimed in claim 1 or 2, wherein, It also has: The intermediate layer, which is connected to the spin-orbit torque wiring; and A conductive layer, which is connected to the spin-orbit torque wiring via the intermediate layer. The coefficient of linear expansion of the material constituting the intermediate layer is between the coefficient of linear expansion of the layer in contact with the intermediate layer and the coefficient of linear expansion of the conductive layer.

9. A magnetoresistive effect element, wherein, have: The magnetized rotating element according to any one of claims 1 to 8; A non-magnetic layer, which is in contact with the first ferromagnetic layer of the magnetized rotating element; and The second ferromagnetic layer, together with the first ferromagnetic layer, sandwiches the non-magnetic layer in between.

10. A magnetic storage device, wherein, It has multiple magnetoresistive effect elements as described in claim 9.

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