Magnetizing rotation element, magnetoresistive effect element, and magnetic memory

Abstract

The present invention provides a magnetization rotation element, a magnetoresistive element, and a magnetic memory that can reduce the amount of current required for operation. [Solution] The magnetization rotation element 100 comprises a spin-orbit torque wiring 20 and a first ferromagnetic layer 1 laminated on the spin-orbit torque wiring, wherein the spin-orbit torque wiring contains a compound with a delafossite-type crystal structure. The delafossite-type crystal structure is one of oxides, oxynitrides, fluorides, and hydroxides.

Description

[Technical Field]

[0001] This disclosure relates to a magnetization rotation element, a magnetoresistive effect element, and a magnetic memory. [Background technology]

[0002] Giant magnetoresistance (GMR) elements, which consist of a multilayer film of a ferromagnetic layer and a non-magnetic layer, and tunnel magnetoresistance (TMR) elements, which use an insulating layer (tunnel barrier layer, barrier layer) in the non-magnetic layer, are known as magnetoresistive elements. Magnetoresistive elements 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 magnetoresistive elements. MRAM reads and writes data by utilizing the property that the resistance of the magnetoresistive elements changes when the direction of magnetization of the two ferromagnetic layers flanking the non-magnetic layer in the magnetoresistive element changes. The direction of magnetization of the ferromagnetic layers can be controlled, for example, by using the magnetic field generated by an electric current, or by using the spin transfer torque (STT) generated by passing an electric current in the stacking direction of the magnetoresistive elements.

[0004] When using STT to rewrite the magnetization direction of a ferromagnetic layer, current is passed in the direction of stacking of the magnetoresistive elements. The writing current can cause degradation of the characteristics of the magnetoresistive elements.

[0005] In recent years, attention has been focused on methods that do not require current to flow in the stacking direction of magnetoresistive elements during writing (for example, Patent Document 1). One such method is a writing method that utilizes spin-orbit torque (SOT). SOT is induced by a spin current generated by spin-orbit interaction or by the Rashba effect at the interface of dissimilar materials. The current required to induce SOT in a magnetoresistive element flows in a direction intersecting the stacking direction of the magnetoresistive elements. In other words, it is not necessary to flow current in the stacking direction of the magnetoresistive elements, and this is expected to extend the lifespan of the magnetoresistive elements. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2017-216286 [Overview of the project] [Problems that the invention aims to solve]

[0007] Magnetic memory has multiple integrated magnetoresistive elements. As the voltage applied to each magnetoresistive element increases, the power consumption of the magnetic memory increases. Therefore, it is necessary to reduce the voltage applied to each magnetoresistive element to suppress the power consumption of the magnetic memory.

[0008] This disclosure is made in view of the above circumstances and aims to provide a method for manufacturing a magnetization rotation element, a magnetoresistive effect element, a magnetic memory, and wiring that operate at a small voltage. [Means for solving the problem]

[0009] This disclosure provides the following means to solve the above problems.

[0010] A magnetization rotation element according to the first embodiment comprises a spin-orbit torque wiring and a first ferromagnetic layer laminated on the spin-orbit torque wiring, wherein the spin-orbit torque wiring contains a compound having a delafossite-type crystal structure. [Effects of the Invention]

[0011] The magnetization rotation element, magnetoresistive element, and magnetic memory described herein can reduce the amount of current required for operation. [Brief explanation of the drawing]

[0012] [Figure 1] This is a circuit diagram of a magnetic memory according to the first embodiment. [Figure 2]Cross-sectional view of a characteristic part of the magnetic memory according to the first embodiment. [Figure 3] Cross-sectional view of the magnetoresistive effect element according to the first embodiment. [Figure 4] Planar view of the magnetoresistive effect element according to the first embodiment. [Figure 5] Diagram showing the crystal structure of an oxide having a delafossite-type crystal structure. [Figure 6] Cross-sectional view of the magnetoresistive effect element according to the first modification. [Figure 7] Cross-sectional view of the magnetoresistive effect element according to the second modification. [Figure 8] Cross-sectional view of the magnetoresistive effect element according to the third modification. [Figure 9] Cross-sectional view of the magnetoresistive effect element according to the fourth modification. [Figure 10] Cross-sectional view of the magnetization rotation element according to the second embodiment.

Mode for Carrying Out the Invention

[0013] Hereinafter, this embodiment will be described in detail with appropriate reference to the drawings. The drawings used in the following description may show the characteristic parts enlarged for convenience of understanding the characteristics, and the dimensional ratios of the respective components may be different from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present disclosure is not limited thereto, and it can be appropriately changed and implemented within the range in which the effects of the present disclosure are achieved.

[0014] First, directions will be defined. One direction on one surface of the substrate Sub (see FIG. 2) to be described later is defined as the x direction, and the direction orthogonal to the x direction is defined as the y direction. The x direction is, for example, the direction from the first conductive layer 31 to the second conductive layer 32. The z direction is the direction orthogonal to the x direction and the y direction. The z direction is an example of the stacking direction in which the respective layers are stacked. Hereinafter, the +z direction may be expressed as "up" and the -z direction may be expressed as "down". The up and down do not necessarily coincide with the direction in which gravity acts.

[0015] 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 to extensions in other directions. Furthermore, in this specification, "connection" is not limited to physical connections. For example, "connection" is not limited to cases where two layers are physically touching, but also includes cases where two layers are connected by another layer in between.

[0016] "First Embodiment" Figure 1 is a diagram of the configuration of a magnetic memory 200 according to the first embodiment. The magnetic memory 200 comprises a plurality of magnetoresistive elements 100, a plurality of write lines WL, a plurality of common lines CL, a plurality of read lines RL, a plurality of first switch elements Sw1, a plurality of second switch elements Sw2, and a plurality of third switch elements Sw3. The magnetic memory 200 is, for example, a magnetic array in which the magnetoresistive elements 100 are arranged in an array.

[0017] Each write wiring WL electrically connects the power supply to one or more magnetoresistive elements 100. Each common wiring CL is used both when writing and reading data. Each common wiring CL electrically connects a reference potential to one or more magnetoresistive elements 100. The reference potential is, for example, ground. The common wiring CL may be provided for each of the multiple magnetoresistive elements 100, or it may be provided across multiple magnetoresistive elements 100. Each read wiring RL electrically connects the power supply to one or more magnetoresistive elements 100. The power supply is connected to the magnetic memory 200 when in use.

[0018] Each magnetoresistive element 100 is connected to a first switch element Sw1, a second switch element Sw2, and a third switch element Sw3. The first switch element Sw1 is connected between the magnetoresistive element 100 and the write wiring WL. The second switch element Sw2 is connected between the magnetoresistive element 100 and the common wiring CL. The third switch element Sw3 is connected to the read wiring RL that spans multiple magnetoresistive elements 100.

[0019] When the first switch element Sw1 and the second switch element Sw2 are turned ON, a write current flows between the write wiring WL and the common wiring CL connected to the predetermined magnetoresistive element 100. As the write current flows, data is written to the predetermined magnetoresistive element 100. When the second switch element Sw2 and the third switch element Sw3 are turned ON, a read current flows between the common wiring CL and the read wiring RL connected to the predetermined magnetoresistive element 100. As the read current flows, data is read from the predetermined magnetoresistive element 100.

[0020] The first switch element Sw1, the second switch element Sw2, and the third switch element Sw3 are elements that control the flow of current. The first switch element Sw1, the second switch element Sw2, and the third switch element Sw3 are, for example, elements that utilize phase changes in the crystal layer, such as transistors and ovonic threshold switches (OTS), elements that utilize changes in band structure, such as metal-insulator transition (MIT) switches, elements that utilize breakdown voltage, such as Zener diodes and avalanche diodes, and elements whose conductivity changes with changes in atomic position.

[0021] In the magnetic memory 200 shown in Figure 1, the magnetoresistive elements 100 connected to the same wiring share a third switch element Sw3. The third switch element Sw3 may be provided on each magnetoresistive element 100. Alternatively, the third switch element Sw3 may be provided on each magnetoresistive element 100, and the first switch element Sw1 or the second switch element Sw2 may be shared among the magnetoresistive elements 100 connected to the same wiring.

[0022] Figure 2 is a cross-sectional view of a characteristic portion of the magnetic memory 200 according to the first embodiment. Figure 2 is a cross-section of the magnetoresistive element 100 cut by the xz plane passing through the center of the width in the y direction of the spin-orbit torque wiring 20, which will be described later.

[0023] The first and second switching elements Sw1 and Sw2 shown in Figure 2 are transistors Tr. The third switching element Sw3 is electrically connected to the readout wiring RL and is located, for example, at a different position in the y-direction in Figure 2. The transistor Tr is, for example, a field-effect transistor and has a gate electrode G, a gate insulating film GI, and a source S and drain D formed on the substrate Sub. The source S and drain D are defined by the direction of current flow and are in the same region. The positional relationship between the source S and drain D may be reversed. The substrate Sub is, for example, a semiconductor substrate.

[0024] The transistor Tr and the magnetoresistive element 100 are electrically connected via via wiring V, a first conductive layer 31, and a second conductive layer 32. The transistor Tr is also connected to the write wiring WL or the common wiring CL via via wiring V. The via wiring V extends, for example, in the z direction. The read wiring RL is connected to the laminate 10 via electrode E. The via wiring V, electrode E, the first conductive layer 31, and the second conductive layer 32 contain conductive materials.

[0025] The magnetoresistive element 100 and the transistor Tr are surrounded by an insulating layer In. The insulating layer In is an insulating layer that insulates between wirings in multilayer wiring and between elements. The insulating layer In is made of, for example, silicon oxide (SiO x ), silicon nitride (SiN x ), silicon carbide (SiC), chromium nitride (CrN), silicon carbonitride (SiCN), silicon oxynitride (SiON), aluminum oxide (Al2O3), zirconium oxide (ZrO3) x Examples include magnesium oxide (MgO), aluminum nitride (AlN), etc.

[0026] Figure 3 is a cross-sectional view of the magnetoresistive element 100. Figure 3 is a cross-section of the magnetoresistive element 100 obtained by cutting it through the xz plane passing through the center of the width in the y direction of the spin-orbit torque wiring 20. Figure 4 is a plan view of the magnetoresistive element 100 as seen from the z direction.

[0027] The magnetoresistive element 100 comprises, 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 laminated on the spin-orbit torque wiring 20. Other layers may 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 be present between each of the first conductive layer 31 and the second conductive layer 32 and the spin-orbit torque wiring 20. The laminate 10 is located in the middle of the current path between the first conductive layer 31 and the second conductive layer 32. The first conductive layer 31 and the second conductive layer 32 are, for example, positioned on either side of the laminate 10 when viewed from the z direction.

[0028] The resistance of the laminate 10 in the z-direction changes as spin is injected into the laminate 10 from the spin-orbit torque wiring 20. The magnetoresistive element 100 is a magnetic element that utilizes spin-orbit torque (SOT), and is sometimes called a spin-orbit torque type magnetoresistive element, spin-injection type magnetoresistive element, or spin-current magnetoresistive element.

[0029] The laminate 10 is sandwiched in the z-direction between the spin-orbit torque wiring 20 and the electrode E (see Figure 2). The laminate 10 is columnar. The shape of the laminate 10 in plan view from the z-direction is, for example, circular, elliptical, or quadrilateral. The side surface of the laminate 10 is, for example, inclined with respect to the z-direction.

[0030] The laminate 10 includes, for example, a first ferromagnetic layer 1, a second ferromagnetic layer 2, and a non-magnetic layer 3. The first ferromagnetic layer 1 is in contact with, for example, a spin-orbit torque wiring 20 and is laminated on the spin-orbit torque wiring 20. Spins are injected into the first ferromagnetic layer 1 from the spin-orbit torque wiring 20. The magnetization of the first ferromagnetic layer 1 changes its orientation direction due to the spin-orbit torque (SOT) caused by the injected spins. The first ferromagnetic layer 1 and the second ferromagnetic layer 2 are sandwiched in the z direction by the non-magnetic layer 3.

[0031] The first ferromagnetic layer 1 and the second ferromagnetic layer 2 each have magnetization. When a predetermined external force is applied, the magnetization direction of the second ferromagnetic layer 2 is less likely to change than that of the first ferromagnetic layer 1. The first ferromagnetic layer 1 is called a magnetization free layer, and the second ferromagnetic layer 2 may be called a magnetization fixed layer or a magnetization reference layer. In the laminate 10 shown in FIG. 3, the magnetization fixed layer is on the side away from the substrate Sub and is called a top pin structure. The resistance value of the laminate 10 changes according to the difference in the relative angle of magnetization between the first ferromagnetic layer 1 and the second ferromagnetic layer 2 sandwiching the non-magnetic layer 3.

[0032] The first ferromagnetic layer 1 and the second ferromagnetic layer 2 contain a ferromagnetic material. The ferromagnetic material is, for example, a metal selected from the group consisting of Cr, Mn, Co, Fe, and Ni, an alloy containing one or more of these metals, an alloy containing at least one element of B, C, and N and these metals, etc. The ferromagnetic material is, for example, Co-Fe, Co-Fe-B, Ni-Fe, Co-Ho alloy, Sm-Fe alloy, Fe-Pt alloy, Co-Pt alloy, CoCrPt alloy.

[0033] The first ferromagnetic layer 1 and the second ferromagnetic layer 2 may contain a Heusler alloy. The Heusler alloy contains an intermetallic compound having a chemical composition of XYZ or X2YZ. 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 species of X, and Z is a typical element of Group III to Group V. The Heusler alloy is, for example, Co2FeSi, Co2FeGe, Co2FeGa, Co2MnSi, Co2Mn 1-a Fe a Al b Si 1-b , Co2FeGe 1-c Ga c etc. The Heusler alloy has a high spin polarization rate.

[0034] The non-magnetic layer 3 contains a non-magnetic material. When the non-magnetic layer 3 is an insulator (a tunnel barrier layer), materials such as Al2O3, SiO2, MgO, and MgAl2O4 can be used. In addition to these, materials in which some of Al, Si, and Mg are substituted with Zn, Be, etc., can also be used. Among these, MgO and MgAl2O4 are materials that can realize coherent tunneling, and therefore spin can be efficiently injected. When the non-magnetic layer 3 is a metal, materials such as Cu, Au, and Ag can be used. Furthermore, when the non-magnetic layer 3 is a semiconductor, materials such as Si, Ge, CuInSe2, CuGaSe2, and Cu(In,Ga)Se2 can be used.

[0035] The laminate 10 may have layers other than the first ferromagnetic layer 1, the second ferromagnetic layer 2, and the non-magnetic layer 3. For example, there may be an underlayer between the spin-orbit torque wiring 20 and the first ferromagnetic layer 1. The underlayer enhances the crystallinity of each layer constituting the laminate 10. Alternatively, for example, there may be a cap layer on the uppermost surface of the laminate 10.

[0036] 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, via a spacer layer. The second ferromagnetic layer 2, the spacer layer, and the ferromagnetic layer form a synthetic antiferromagnetic structure (SAF structure). The synthetic antiferromagnetic structure consists of two magnetic layers sandwiching a non-magnetic layer. The antiferromagnetic coupling between the second ferromagnetic layer 2 and the ferromagnetic layer increases the coercivity of the second ferromagnetic layer 2 compared to the case without a ferromagnetic layer. The ferromagnetic layer is, for example, IrMn, PtMn, etc. The spacer layer includes, for example, at least one selected from the group consisting of Ru, Ir, and Rh.

[0037] The spin-orbit torque wiring 20, for example, has a length in the x-direction greater than the length in the y-direction when viewed from the z-direction, and extends in the x-direction. The writing current flows through the spin-orbit torque wiring 20 in the x-direction. 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.

[0038] 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. The spin-orbit torque wiring 20, for example, imparts a spin-orbit torque (SOT) to the magnetization of the first ferromagnetic layer 1 sufficient to reverse its magnetization. The spin Hall effect is a phenomenon in which, when an electric current flows, a spin current is induced in a direction perpendicular to the direction of the current flow, based on spin-orbit interaction. The spin Hall effect is similar to the ordinary Hall effect in that the direction of motion (movement) of moving charges (electrons) is bent. In the ordinary Hall effect, the direction of motion of charged particles moving in a magnetic field is bent by the Lorentz force. In contrast, in the spin Hall effect, the direction of spin movement is bent simply by the movement of electrons (simply by the flow of current), even without a magnetic field.

[0039] For example, when current flows through the spin-orbit torque wiring 20, the first spin, which is oriented in one direction, and the second spin, which is oriented in the opposite direction to the first spin, are both bent by the spin Hall effect in directions perpendicular to the direction of the current I. For example, the first spin, which is oriented in the -y direction, is bent in the +z direction, and the second spin, which is oriented in the +y direction, is bent in the -z direction.

[0040] In non-magnetic materials (materials that are not ferromagnetic), the number of electrons in the first spin and the number of electrons in the second spin, which are generated by the spin Hall effect, are equal. That is, the number of electrons in the first spin moving in the +z direction is equal to the number of electrons in the second spin moving in the -z direction. The first and second spins flow in a direction that eliminates the uneven distribution of spins. In the movement of the first and second spins in the z direction, the flow of charge cancels each other out, so the amount of current is zero. A spin current that does not produce an electric current is specifically called a pure spin current.

[0041] The flow of electrons in the first spin is J ↑ , the flow of electrons with second spin is J ↓ , spin current J S Expressed as, J S =J ↑ -J ↓ It is defined as: Spin current J SThis occurs in the z direction. The first spin is injected into the first ferromagnetic layer 1 from the spin-orbit torque wiring 20.

[0042] The spin-orbit torque wiring 20 contains a compound with a delafossite-type crystal structure. The spin-orbit torque wiring 20 may consist of a compound with a delafossite-type crystal structure.

[0043] Compounds with a delafossite-type crystal structure are, for example, oxides, oxynitrides, fluorides, or hydroxides. Oxides are an example of a compound with a delafossite-type crystal structure. Oxides are easy to handle.

[0044] Oxides with a delafoscite-type crystal structure are represented by the empirical formula ABO2. In the empirical formula, A is one or more elements selected from the group consisting of Cu, Ag, Pt, Pd, and Au. In the empirical formula, B is one or more trivalent metal elements selected from the group consisting of Al, Ga, In, Tl, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Rh, Ir, La, Nd, Sm, and Eu. The above empirical formula is described in terms of stoichiometric composition, but deviations from stoichiometric composition are permitted as long as the crystal structure is maintained.

[0045] For example, an oxide with a delafossite-type crystal structure may have oxygen vacancies. Oxygen vacancies in the oxide reduce the spatial symmetry of the spin-orbit torque wiring 20. When the symmetry within the spin-orbit torque wiring 20 is low, a strong spin-orbit interaction occurs between conduction electrons and localized electrons, increasing the amount of spin injected into the first ferromagnetic layer 1. Furthermore, the conductivity of the spin-orbit torque wiring 20 can be adjusted by the degree of oxygen vacancies in the oxide.

[0046] Figure 5 shows the crystal structure of an oxide having a delafossite-type crystal structure. The delafossite-type crystal structure is a layered structure in which A faces and BO2 faces formed by BO6 octahedra sharing edges are alternately stacked.

[0047] Because the delafossite crystal structure has an A-plane that extends in the in-plane direction, compounds with a delafossite crystal structure exhibit high electrical conductivity. For example, oxides with a delafossite crystal structure exhibit electrical conductivity comparable to that of elemental metals. At room temperature, the electrical resistivity is, for example, 2.6 μΩcm for PdCoO2, 8.1 μΩcm for PdCrO2, 9.1 μΩcm for PdRhO2, and 2.3 μΩcm for PtCoO2.

[0048] The magnetization of the first ferromagnetic layer 1 reverses when the current density in the spin-orbit torque wiring 20 exceeds the reversal current density. If the electrical conductivity of the spin-orbit torque wiring 20 is high, a large current can flow through the spin-orbit torque wiring 20 even with a small potential difference, thereby reducing the power consumption required for the operation of the magnetoresistive element.

[0049] Furthermore, the delafossite crystal structure has A-planes and BO2-planes in the c-axis direction, resulting in low spatial symmetry in the c-axis direction. In addition, even between adjacent A-planes and adjacent BO2-planes, the sites are shifted in the a-axis and b-axis directions, resulting in low spatial symmetry in the a-axis and b-axis directions. Low symmetry within the spin-orbit torque wiring 20 leads to strong spin-orbit interaction between conduction electrons and localized electrons, increasing the amount of spin injected into the first ferromagnetic layer 1. In other words, if the spin-orbit torque wiring 20 has a delafossite crystal structure, more spins can be injected into the first ferromagnetic layer 1 with the same amount of current as when it does not have a delafossite crystal structure, thereby reducing the power consumption required for the operation of the magnetoresistive element.

[0050] In the composition formula, A may be at least one of Pt and Pd. When A is Pt or Pd, the electrical resistivity of the spin-orbit torque wiring 20 is lower compared to when A is any other element. As a result, the power consumption required for the operation of the magnetoresistive element can be further reduced.

[0051] In the composition formula, A may be at least one of Cu and Ag. Cu and Ag generally have long spin diffusion lengths. When the A surface is Cu or Ag, the diffusion of spins generated within the spin-orbit torque wiring 20 across the A surface can be suppressed. By suppressing spin diffusion within the spin-orbit torque wiring 20, spins can be injected into the first ferromagnetic layer 1 more efficiently.

[0052] In the composition formula, B may be at least one of Rh and Ir. Rh and Ir have large atomic radii and electrons tend to be localized. These elements create strong spin-orbit interactions between conduction electrons and localized electrons. When B contains Rh or Ir, the amount of spin injected into the first ferromagnetic layer 1 can be increased.

[0053] Examples of compounds with a delafossite-type crystal structure include PdCoO2, PdFeO2, PdNiO2, PdCrO2, PdRhO2, PdIrO2, PtCoO2, PtFeO2, PtNiO2, PtCrO2, PtRhO2, PtIrO2, CuCoO2, CuFeO2, CuNiO2, CuCrO2, CuRhO2, CuIrO2, AgCoO2, AgCrO2, AgFeO2, AgNiO2, AgRhO2, AgIrO2, etc.

[0054] The thickness of the spin-orbit torque wiring 20 is, for example, 2 nm or more. The thickness of the spin-orbit torque wiring 20 may also be, for example, 20 nm or less.

[0055] The spin-orbit torque wiring 20 may also contain a magnetic metal or a topological insulator. A topological insulator is a material in which the interior is an insulator or a high-resistance material, but a spin-polarized metallic state is generated on its surface.

[0056] 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 made of materials with excellent conductivity. The first conductive layer 31 and the second conductive layer 32 are, for example, Al, Cu, W, and Cr.

[0057] Next, a method for manufacturing the magnetoresistive element 100 will be described. The magnetoresistive element 100 is formed by a layer stacking process and a processing process in which a portion of each layer is processed into a predetermined shape. For the layer stacking, sputtering, chemical vapor deposition (CVD), electron beam deposition (EB deposition), atomic layer deposition (ALD), ion beam deposition (IBD), molecular beam epitaxy (MBE), etc., can be used. For processing each layer, photolithography or the like can be used.

[0058] First, impurities are doped into predetermined positions 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 the drain D. The source S, drain D, gate insulating film GI, and gate electrode G form the transistor Tr.

[0059] Next, an insulating layer In is formed to cover the transistor Tr. An opening is also formed in the insulating layer In, and a conductive material is filled into the opening to form a via wiring V, a first conductive layer 31, and a second conductive layer 32. The writing wiring WL and common wiring CL are formed by laminating the insulating layer In to a predetermined thickness, then forming grooves in the insulating layer In and filling the grooves with a conductive material.

[0060] Next, a compound with a delafossite-type crystal structure is deposited on one surface of the insulating layer In, the first conductive layer 31, and the second conductive layer 32. For example, an oxide with a delafossite-type crystal structure can be produced by simultaneously sputtering elements A and B in an oxygen atmosphere. Alternatively, an oxide with a delafossite-type crystal structure can be produced by simultaneously sputtering elements A and B, followed by plasma oxidation or oxidation by oxygen introduction. Alternatively, an oxide with a delafossite-type crystal structure can be produced by sputtering an alloy consisting of elements A and B, followed by plasma oxidation or oxidation by oxygen introduction. Alternatively, an oxide with a delafossite-type crystal structure can be produced by sputtering element A, then sputtering element B, and then performing plasma oxidation or oxidation by oxygen introduction. In this case, the order of sputtering element A, sputtering element B, and oxidation may be changed as appropriate, or the sequence "sputtering element A, sputtering element B, and oxidation" may be repeated multiple times. For example, an oxide with a delafossite-type crystal structure is an oxide composed of elements A and B, such as ABO x It can be fabricated by sputtering. Also, for example, an oxide with a delafossite-type crystal structure is an oxide (BO) composed of element A and element B. x ), can be fabricated by simultaneous sputtering. Also, for example, an oxide with a delafossite-type crystal structure can be made from element A into an oxide (AO x ) and element B can be produced by simultaneously sputtering them. In either case, heat treatment may be performed as appropriate. The preferred heat treatment temperature is between 200°C and 400°C. This prevents unwanted element diffusion while ensuring a uniform composition of the oxide with a delafossite-type crystal structure within the film.

[0061] Next, a ferromagnetic layer, a non-magnetic layer, a ferromagnetic layer, and a hard mask layer are sequentially stacked on a layer containing a compound with a delafossite-type crystal structure. Then, the hard mask layer is processed into a predetermined shape. The predetermined shape is, for example, the outer shape of the spin-orbit torque wiring 20. Next, the layer containing the compound with a delafossite-type crystal structure, the ferromagnetic layer, the non-magnetic layer, and the ferromagnetic layer are processed into a predetermined shape all at once via the hard mask layer. The layer containing the compound with a delafossite-type crystal structure becomes the spin-orbit torque wiring 20 when processed into the predetermined shape.

[0062] Next, the unnecessary portion of the hard mask layer in the x-direction is removed. The hard mask layer becomes the outer shape of the laminate 10. Then, the unnecessary portion of the laminate formed on the spin-orbit torque wiring 20 in the x-direction is removed through the hard mask layer. The laminate 10 is processed into a predetermined shape and becomes the laminate 10. The hard mask layer becomes the electrode E. Then, the area around the laminate 10 and the spin-orbit torque wiring 20 is filled with an insulating layer In to obtain the magnetoresistive element 100.

[0063] The magnetoresistive element 100 according to the first embodiment has high electrical conductivity in the spin-orbit torque wiring 20, allowing a large current to flow even with a small potential difference. The magnetoresistive element 100 according to the first embodiment can reduce the writing potential required to reverse the magnetization of the first ferromagnetic layer 1. When the writing potential difference of each element is small, the overall power consumption of the magnetic memory 200 can be reduced.

[0064] The reason why a large current can flow through the spin-orbit torque wiring 20 with a small potential difference is that the spin-orbit torque wiring 20 has a delafossite-type structure. It is thought that the A-plane of the delafossite-type structure acts as a conduction path for conduction electrons, thereby increasing the electrical conductivity of the spin-orbit torque wiring.

[0065] An example of a magnetoresistive element 100 according to the first embodiment has been shown above, but additions, omissions, substitutions, and other modifications to the configuration are possible without departing from the spirit of this disclosure.

[0066] (First variation) Figure 6 is a cross-sectional view of the magnetoresistive element 101 according to the first modified example. Figure 6 is an xz cross-section passing through the center in the y direction of the spin-orbit torque wiring 20. In Figure 6, components identical to those in Figure 3 are denoted by the same reference numerals and their descriptions are omitted.

[0067] The magnetoresistive element 101 according to the first modified example has a first intermediate layer 40 between the spin-orbit torque wiring 20 and the first ferromagnetic layer 1. The first intermediate layer 40 is, for example, located on the spin-orbit torque wiring 20.

[0068] The first intermediate layer 40 contains a heavy metal in the non-magnetic layer. The heavy metal is a metal having an atomic number (specific gravity) greater than or equal to yttrium (Y). A non-magnetic heavy metal is, for example, a non-magnetic metal with a large atomic number of 39 or more that has d or f electrons in its outermost shell. The first intermediate layer 40 contains, for example, one or more of the following: Au, Bi, Hf, Ir, Mo, Pd, Pt, Rh, Ru, Ta, and W. The main element of the first intermediate layer 40 is preferably one of these elements, for example.

[0069] The nonmagnetic heavy metal constituting the first intermediate layer 40 exhibits stronger spin-orbit interaction than other metals. Therefore, the writing current flowing through the first intermediate layer 40 also generates a spin current. Furthermore, the Rashba effect occurs at the interface between the first intermediate layer 40 and the spin-orbit torque wiring 20. By providing the first intermediate layer 40 between the spin-orbit torque wiring 20 and the first ferromagnetic layer 1, more spins can be injected into the first ferromagnetic layer 1.

[0070] The first intermediate layer 40 does not have to be a perfectly continuous layer; for example, it may be a continuous film having multiple openings or a layer containing multiple components scattered in an island-like manner. Even when the first intermediate layer 40 is present, the spin-orbit torque wiring 20 and the first ferromagnetic layer 1 are in direct contact in some areas, which further suppresses the diffusion of spins generated in the spin-orbit torque wiring 20 in the first intermediate layer 40 before they reach the first ferromagnetic layer 1.

[0071] The thickness of the first intermediate layer 40 is, for example, less than or equal to the spin diffusion length of the material constituting the layer. Furthermore, the thickness of the first intermediate layer 40 is, for example, less than five times the bonding radius of the elements constituting the first intermediate layer 40. The bonding radius is half the distance between adjacent atoms in the crystal of the elements constituting the first intermediate layer 40. The thinness of the first intermediate layer 40 suppresses the diffusion of spins generated in the spin-orbit torque wiring 20 before they reach the first ferromagnetic layer 1. The first intermediate layer 40 can be deposited by sputtering.

[0072] The magnetoresistive element 101 according to the first modified example has a spin-orbit torque wiring 20 containing a compound with a delafossite-type crystal structure, and therefore produces the same effect as the magnetoresistive element 100 described above.

[0073] (Second variation) Figure 7 is a cross-sectional view of the magnetoresistive element 102 according to the second modified example. Figure 7 is an xz cross-section passing through the center in the y direction of the spin-orbit torque wiring 20. In Figure 7, components identical to those in Figure 3 are denoted by the same reference numerals and their descriptions are omitted.

[0074] The magnetoresistive element 102 according to the second modified example has a second intermediate layer 50 between the spin-orbit torque wiring 20 and the first ferromagnetic layer 1. The second intermediate layer 50 is, for example, located on the spin-orbit torque wiring 20.

[0075] The second intermediate layer 50 contains one or more elements selected from the group consisting of Cu, Al, Si, and Al. For example, the second intermediate layer 50 consists of one or more elements selected from the group consisting of Cu, Al, Si, and Al. These elements have excellent conductivity. Therefore, the resistance of the entire wiring, including the second intermediate layer 50 and the spin-orbit torque wiring 20, can be further reduced. Furthermore, these elements have a long spin diffusion length. Therefore, the second intermediate layer 50 does not easily diffuse spin. The spins generated in the spin-orbit torque wiring 20 are efficiently supplied to the first ferromagnetic layer 1, even through the second intermediate layer 50.

[0076] Furthermore, when the second intermediate layer 50 is provided, an interface between dissimilar materials is created between the second intermediate layer 50 and the spin-orbit torque wiring 20. At the interface between dissimilar materials, the Rashba effect occurs, increasing the amount of spin injected into the first ferromagnetic layer 1.

[0077] The second intermediate layer 50 does not have to be a perfectly continuous layer; for example, it may be a continuous film having multiple openings or a layer containing multiple components scattered in an island-like manner. The thickness of the second intermediate layer 50 is, for example, less than or equal to the spin diffusion length of the material constituting the layer. The second intermediate layer 50 can be deposited by sputtering.

[0078] The magnetoresistive element 102 according to the second modified example has a spin-orbit torque wiring 20 containing a compound with a delafossite-type crystal structure, and therefore exhibits the same effects as the magnetoresistive element 100 described above. Furthermore, by splitting the writing current between the second intermediate layer 50 and the spin-orbit torque wiring 20, heat generation in the spin-orbit torque wiring 20 can be suppressed. In addition, the overall resistance of the wiring can be reduced.

[0079] (Third variation) Figure 8 is a cross-sectional view of the magnetoresistive element 103 according to the third modified example. Figure 8 is an xz cross-section passing through the center in the y direction of the spin-orbit torque wiring 21. In Figure 8, components identical to those in Figure 3 are denoted by the same reference numerals and their descriptions are omitted.

[0080] The spin-orbit torque wiring 21 of the magnetoresistive element 103 according to the third modified example differs from the spin-orbit torque wiring 20 of the magnetoresistive element 100 in that it consists of multiple layers. The spin-orbit torque wiring 21 consists of, for example, a first layer 21A, a second layer 21B, a third layer 21C, and a fourth layer 21D. Here, we illustrate the case where the spin-orbit torque wiring 21 has four layers, but the number of layers constituting the spin-orbit torque wiring 21 is not particularly limited.

[0081] Each of the first layer 21A, second layer 21B, third layer 21C, and fourth layer 21D contains a compound with a delafossite-type crystal structure. Two adjacent layers among the first layer 21A, second layer 21B, third layer 21C, and fourth layer 21D have different compositions. Because each of the first layer 21A, second layer 21B, third layer 21C, and fourth layer 21D contains a compound with a delafossite-type crystal structure, they have excellent electrical conductivity and generate strong spin-orbit interaction. Furthermore, the interfaces of each layer are interfaces of different materials, generating the Rashba effect.

[0082] The magnetoresistive element 103 according to the third modified example has a spin-orbit torque wiring 21 containing a compound with a delafossite-type crystal structure, and therefore exhibits the same effects as the magnetoresistive element 100 described above. Furthermore, because the spin-orbit torque wiring 21 has multiple layers, the amount of spin injected into the first ferromagnetic layer 1 can be increased by the Rashba effect.

[0083] (Fourth variation) Figure 9 is a cross-sectional view of the magnetoresistive element 104 according to the fourth modified example. Figure 9 is an xz cross-section passing through the center in the y direction of the spin-orbit torque wiring 20. In Figure 9, components identical to those in Figure 3 are denoted by the same reference numerals and their descriptions are omitted.

[0084] The laminate 10 shown in Figure 9 has a bottom-pin structure in which the magnetization fixed layer (second ferromagnetic layer 2) is located near the substrate Sub. When the magnetization fixed layer is on the substrate Sub side, the stability of the magnetization of the magnetization fixed layer is increased, and the MR ratio of the magnetoresistive element 104 is increased. The spin-orbit torque wiring 20 is, for example, located on the laminate 10. The first conductive layer 31 and the second conductive layer 32 are located on the spin-orbit torque wiring 20.

[0085] The magnetoresistive element 104 according to the fourth modified example differs only in the positional relationship of its components, and the same effect as the magnetoresistive element 100 according to the first embodiment can be obtained.

[0086] "Second Embodiment" Figure 10 is a cross-sectional view of the magnetization rotation element 105 according to the second embodiment. In Figure 1, the magnetization rotation element 105 is replaced with the magnetoresistive effect element 100 according to the first embodiment.

[0087] The magnetization rotation element 105 evaluates the light reflected by the first ferromagnetic layer 1 after light is incident on it. When the orientation direction of the magnetization changes due to the magnetic 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 a video display device or the like, by utilizing the difference in the deflection state of light.

[0088] In addition, the magnetization rotation element 105 can be used independently as an anisotropic magnetic sensor, an optical element utilizing the magnetic Faraday effect, and the like.

[0089] The spin-orbit torque wiring 20 of the magnetization rotation element 105 has a compound with a delafossite-type crystal structure.

[0090] The magnetization rotation element 105 according to the second embodiment is simply a magnetoresistive element 100 with the non-magnetic layer 3 and the second ferromagnetic layer 2 removed, and the same effects as the magnetoresistive element 100 according to the first embodiment can be obtained.

[0091] While preferred embodiments of the present disclosure have been illustrated based on the first embodiment, the second embodiment, and variations, the present disclosure is not limited to these embodiments. For example, characteristic configurations in each embodiment and variation may be applied to other embodiments and variations. [Explanation of Symbols]

[0092] 1…First ferromagnetic layer, 2…Second ferromagnetic layer, 3…Non-magnetic layer, 10…Laminate, 20, 21…Spin-orbit torque wiring, 31…First conductive layer, 32…Second conductive layer, 40…First intermediate layer, 50…Second intermediate layer, 100, 101, 102, 103, 104…Magnetoresistive effect element, 105…Magnetization rotation element, 200…Magnetic memory, CL…Common wiring, RL…Read wiring, WL…Write wiring, In…Insulating layer

Claims

1. Spin orbit torque wiring, The spin-orbit torque wiring comprises a first ferromagnetic layer laminated on the spin-orbit torque wiring, The spin-orbit torque wiring is a magnetized rotation element containing a compound with a delafossite-type crystal structure.

2. The magnetization rotation element according to claim 1, wherein the compound is an oxide.

3. The aforementioned oxide has a stoichiometric composition of ABO ２ It is represented by the chemical formula, In the above compositional formula, A is one or more elements selected from the group consisting of Cu, Ag, Pt, Pd, and Au. The magnetization rotation element according to claim 2, wherein B in the composition formula is one or more trivalent metal elements selected from the group consisting of Al, Ga, In, Tl, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Rh, Ir, La, Nd, Sm, and Eu.

4. The magnetization rotation element according to claim 3, wherein A in the above composition formula is at least one of Pt and Pd.

5. The magnetization rotation element according to claim 3, wherein A in the above composition formula is at least one of Cu and Ag.

6. The magnetization rotation element according to claim 3, wherein B in the composition formula is at least one of Rh and Ir.

7. The magnetization rotation element according to claim 2, wherein the oxide is oxygen-deficient.

8. A first intermediate layer is provided between the first ferromagnetic layer and the spin-orbit torque wiring, The magnetization rotation element according to claim 1, wherein the first intermediate layer contains a heavy metal with an atomic number greater than yttrium.

9. A second intermediate layer is provided between the first ferromagnetic layer and the spin-orbit torque wiring. The magnetization rotation element according to claim 1, wherein the second intermediate layer contains one or more elements selected from the group consisting of Cu, Al, Si, and Al.

10. The spin-orbit torque wiring has multiple layers, The magnetization rotation element according to claim 1, wherein each of the plurality of layers comprises a compound having a delafossite-type crystal structure.

11. The magnetization rotation element according to claim 1, A non-magnetic layer in contact with the first ferromagnetic layer of the magnetization rotation element, A magnetoresistive element comprising: a first ferromagnetic layer and a second ferromagnetic layer sandwiching the non-magnetic layer between them.

12. A magnetic memory comprising a plurality of magnetoresistive elements as described in claim 11.

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