WO2022123726A1

WO2022123726A1 - Magnetization rotation element, magnetoresistance effect element, magnetic memory, and production method for wiring

Info

Publication number: WO2022123726A1
Application number: PCT/JP2020/046050
Authority: WO
Inventors: 智生佐々木
Original assignee: Tdk株式会社
Priority date: 2020-12-10
Filing date: 2020-12-10
Publication date: 2022-06-16
Also published as: JP2022092571A

Abstract

This magnetization rotation element comprises spin-orbit torque wiring and a first ferromagnetic layer layered on the spin-orbit torque wiring, wherein the spin-orbit torque wiring includes a compound having a pyrochlore structure.

Description

Manufacturing method of magnetized rotating element, magnetoresistive element, magnetic memory and wiring

The present invention relates to a magnetization rotating element, a magnetoresistive element, a magnetic memory, and a method for manufacturing wiring.

Giant magnetoresistive (GMR) elements consisting of a multilayer film of a ferromagnetic layer and a non-magnetic layer, and tunnel magnetoresistive (TMR) elements using an insulating layer (tunnel barrier layer, barrier layer) as the non-magnetic layer are magnetic resistance. Known as an effect element. Magnetoresistive elements can be applied to magnetic sensors, high frequency components, magnetic heads and non-volatile random access memory (MRAM).

MRAM is a storage element in which a magnetoresistive element is integrated. The MRAM reads and writes data by utilizing the characteristic that the resistance of the magnetoresistive sensor changes when the direction of mutual magnetization of the two ferromagnetic layers sandwiching the non-magnetic layer in the magnetoresistive sensor changes. The direction of magnetization of the ferromagnetic layer is controlled by using, for example, a magnetic field generated by an electric current. Further, for example, the direction of magnetization of the ferromagnetic layer is controlled by utilizing the spin transfer torque (STT) generated by passing a current in the stacking direction of the magnetoresistive effect element.

When rewriting the direction of magnetization of the ferromagnetic layer using STT, a current is passed in the stacking direction of the magnetoresistive element. The write current causes deterioration of the characteristics of the magnetoresistive element.

In recent years, attention has been focused on a method in which a current does not have to flow in the stacking direction of the magnetoresistive element during writing (for example, Patent Document 1). One of the methods is a writing method using spin-orbit torque (SOT). SOT is induced by the spin current generated by spin-orbit interaction or the Rashba effect at the interface of dissimilar materials. The current for inducing SOT in the magnetoresistive element flows in the direction intersecting the stacking direction of the magnetoresistive element. That is, it is not necessary to pass a current in the stacking direction of the magnetoresistive element, and it is expected that the life of the magnetoresistive element will be extended.

Japanese Unexamined Patent Publication No. 2017-216286

The magnetic memory has a plurality of integrated magnetoresistive elements. As the amount of current applied to each magnetoresistive effect element increases, the power consumption of the magnetic memory increases. It is required to reduce the amount of current applied to each magnetoresistive effect element and suppress the power consumption of the magnetic memory.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a magnetization rotating element, a magnetoresistive element, a magnetic memory, and wiring that operate with a small current.

The present invention provides the following means for solving the above problems.

(1) The magnetizing rotating element according to the first aspect includes a spin-orbit torque wiring and a first ferromagnetic layer laminated on the spin-orbit torque wiring, and the spin-orbit torque wiring is a compound having a pyrochlor structure. including.

(2) In the magnetization rotating device according to the above aspect, the compound may be an oxide.

(3) In the magnetizing rotating element according to the above aspect, the oxide is represented by the composition formula of R ₂ Ir ₂ O ₇ in the stoichiometric composition, and R in the composition formula is Pr, Nd, Sm, Eu, It may be one or more elements selected from the group consisting of Gd, Tb, Dy and Ho.

(4) In the magnetization rotating element according to the above aspect, R in the composition formula contains a first element, and the first element may be at least one of Pr and Nd.

(5) In the magnetizing rotating element according to the above aspect, R in the composition formula contains a first element and a second element, and the first element is at least one of Pr and Nd, and the second element. The element may be one or more elements selected from the group consisting of Sm, Eu, Gd, Tb, Dy and Ho.

(6) In the magnetization rotating element according to the above aspect, the composition ratio of the second element may be smaller than the composition ratio of the first element.

(7) In the magnetization rotating element according to the above aspect, the oxide may be oxygen-deficient.

(8) In the magnetized rotating element according to the above aspect, the spin-orbit torque wiring may have an electrical resistivity of 1 mΩ · cm or more.

(9) In the magnetized rotating element according to the above aspect, the spin-orbit torque wiring may have an electrical resistivity of 10 mΩ · cm or less.

(10) The magnetizing rotating element according to the above aspect may have a first intermediate layer between the first ferromagnetic layer and the spin-orbit torque wiring, and the first intermediate layer is an atom from yttrium. Contains heavy metals with high numbers.

(11) The magnetizing rotating element according to the above aspect may have a second intermediate layer between the first ferromagnetic layer and the spin orbit torque wiring, and the second intermediate layer may be Cu, Al. , Si and one or more elements selected from the group consisting of Al.

(12) The magnetizing rotating element according to the above embodiment may have one or more first intermediate layers and two or more intermediate layers between the first ferromagnetic layer and the spin orbit torque wiring. The first intermediate layer contains a heavy metal having an atomic number larger than that of yttrium, and the second intermediate layer contains one or more elements selected from the group consisting of Cu, Al, Si and Al.

(13) The magnetic resistance effect element according to the second aspect is the magnetized rotating element according to the above aspect, a non-magnetic layer in contact with the first ferromagnetic layer of the magnetized rotating element, and the first ferromagnetic layer. A second ferromagnetic layer with a non-magnetic layer sandwiched between them is provided.

(14) The magnetic memory according to the third aspect includes a plurality of magnetoresistive elements according to the above aspect.

(15) The method for manufacturing wiring according to the fourth aspect includes a first film forming step of forming an oxide layer containing a pyrochlore structure by DC sputtering of a metal at the same time as or after RF sputtering of an oxide.

(16) In the method for producing wiring according to the above aspect, the oxide is one selected from the group consisting of R ₂ O ₃ (R is Pr, Nd, Sm, Eu, Gd, Tb, Dy and Ho. The above elements), and the metal may be Ir.

(17) In the method for manufacturing wiring according to the above aspect, the first film forming step may be performed in an oxygen atmosphere.

(18) The method for manufacturing a wiring according to the above aspect may include a second film forming step of forming a heavy metal layer containing a heavy metal having a larger atomic number than yttrium after the film forming step. The gas pressure in the film forming step is higher than the gas pressure in the first film forming step.

(19) The method for manufacturing a wiring according to the above aspect is selected from a second film forming step of forming a heavy metal layer containing a heavy metal having a larger atomic number than yttrium and a group consisting of Cu, Al, Si and Al1. A third film forming step for forming a layer containing an element of a kind or more may be further provided after the first forming step, and the second forming step and the third forming step are alternately performed. To do.

The method for manufacturing a magnetization rotating element, a magnetoresistive effect element, a magnetic memory, and wiring according to the present invention can reduce the amount of current required for operation.

It is a circuit diagram of the magnetic memory which concerns on 1st Embodiment. It is sectional drawing of the characteristic part of the magnetic memory which concerns on 1st Embodiment. It is sectional drawing of the magnetic resistance effect element which concerns on 1st Embodiment. It is a top view of the magnetoresistive effect element which concerns on 1st Embodiment. It is a figure which shows the crystal structure of a pyrochlore structure. It is sectional drawing of the magnetic resistance effect element which concerns on the 1st modification. It is sectional drawing of the magnetic resistance effect element which concerns on the 2nd modification. It is sectional drawing of the magnetic resistance effect element which concerns on 3rd modification. It is sectional drawing of the magnetic resistance effect element which concerns on 4th modification. It is sectional drawing of the magnetization rotating element which concerns on 2nd Embodiment.

Hereinafter, this embodiment will be described in detail with reference to the figures as appropriate. In the drawings used in the following description, the featured portions may be enlarged for convenience in order to make the features easy to understand, and the dimensional ratio of each component may be different from the actual one. The materials, dimensions, and the like exemplified in the following description are examples, and the present invention is not limited thereto, and can be appropriately modified and carried out within the range in which the effects of the present invention are exhibited.

First, define the direction. One direction of one surface of the substrate Sub (see FIG. 2) 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, a direction from the first conductive layer 31 to the second conductive layer 32. The z direction is a direction orthogonal to the x direction and the y direction. The z direction is an example of the stacking direction in which each layer is laminated. Hereinafter, the + z direction may be expressed as “up” and the −z direction may be expressed as “down”. The top and bottom do not always match the direction in which gravity is applied.

As used herein, "extending in the x direction" means that, for example, the dimension in the x direction is larger than the smallest dimension among the dimensions in the x direction, the y direction, and the z direction. The same applies when extending in other directions. Further, the term "connection" as used herein is not limited to the case of being physically connected. For example, not only when two layers are physically in contact with each other, but also when two layers are connected by sandwiching another layer between them is included in "connection".

"First embodiment"
FIG. 1 is a configuration diagram of a magnetic memory 200 according to the first embodiment. The magnetic memory 200 includes a plurality of magnetoresistive elements 100, a plurality of write wiring WLs, a plurality of common wiring CLs, a plurality of read wiring RLs, a plurality of first switching elements Sw1, and a plurality of second switching elements. It includes Sw2 and a plurality of third switching elements Sw3. The magnetic memory 200 is, for example, a magnetic array in which the magnetoresistive effect elements 100 are arranged in an array.

Each write wiring WL electrically connects the power supply and one or more magnetoresistive elements 100. The common wiring CL is wiring used both when writing data and when reading data, respectively. Each of the common wiring CLs electrically connects the reference potential and one or more magnetoresistive elements 100. The reference potential is, for example, ground. The common wiring CL may be provided in each of the plurality of magnetoresistive elements 100, or may be provided across the plurality of magnetoresistive elements 100. The readout wiring RL electrically connects the power supply and one or more magnetoresistive elements 100, respectively. The power supply is connected to the magnetic memory 200 at the time of use.

Each magnetoresistive element 100 is connected to the first switching element Sw1, the second switching element Sw2, and the third switching element Sw3, respectively. The first switching element Sw1 is connected between the magnetoresistive effect element 100 and the write wiring WL. The second switching element Sw2 is connected between the magnetoresistive effect element 100 and the common wiring CL. The third switching element Sw3 is connected to the read wiring RL extending over the plurality of magnetoresistive element 100.

When the first switching element Sw1 and the second switching element Sw2 are turned on, a write current flows between the write wiring WL connected to the predetermined magnetoresistive effect element 100 and the common wiring CL. When the write current flows, data is written to the predetermined magnetoresistive element 100. When the second switching element Sw2 and the third switching element Sw3 are turned on, a read current flows between the common wiring CL connected to the predetermined magnetoresistive element 100 and the read wiring RL. When the read current flows, data is read from the predetermined magnetoresistive element 100.

The first switching element Sw1, the second switching element Sw2, and the third switching element Sw3 are elements that control the flow of current. The first switching element Sw1, the second switching element Sw2, and the third switching element Sw3 are, for example, a transistor, an element such as an Ovonic Threshold Switch (OTS) that utilizes a phase change of a crystal layer, and a metal insulator transition. An element such as a (MIT) switch that utilizes a change in band structure, an element that utilizes a breakdown voltage such as a Zener diode and an avalanche diode, and an element whose conductivity changes as the atomic position changes.

In the magnetic memory 200 shown in FIG. 1, the magnetoresistive element 100 connected to the same wiring shares the third switching element Sw3. The third switching element Sw3 may be provided in each magnetoresistive element 100. Further, a third switching element Sw3 may be provided in each magnetoresistive element 100, and the first switching element Sw1 or the second switching element Sw2 may be shared by the magnetoresistive element 100 connected to the same wiring.

FIG. 2 is a cross-sectional view of a characteristic portion of the magnetic memory 200 according to the first embodiment. FIG. 2 is a cross section of the magnetoresistive effect element 100 cut along the xz plane passing through the center of the width in the y direction of the spin-orbit torque wiring 20 described later.

The first switching element Sw1 and the second switching element Sw2 shown in FIG. 2 are transistor Trs. The third switching element Sw3 is electrically connected to the read wiring RL and is, for example, at a different position in the y direction in FIG. The transistor Tr is, for example, a field effect transistor, and has a gate electrode G, a gate insulating film GI, a source S formed on the substrate Sub, and a drain D. The source S and the drain D are defined by the current flow direction, and they are in the same region. The positional relationship between the source S and the drain D may be inverted. The substrate Sub is, for example, a semiconductor substrate.

The transistor Tr and the magnetoresistive sensor 100 are electrically connected via the via wiring V, the first conductive layer 31 and the second conductive layer 32. Further, the transistor Tr and the write wiring WL or the common wiring CL are connected by the via wiring V. The via wiring V extends in the z direction, for example. The read wiring RL is connected to the laminated body 10 via the electrode E. The via wiring V, the electrode E, the first conductive layer 31 and the second conductive layer 32 include a material having conductivity.

The periphery of the magnetoresistive effect element 100 and the transistor Tr is covered with an insulating layer In. The insulating layer In is an insulating layer that insulates between the wirings of the multilayer wiring and between the elements. The insulating layer In may be, for example, silicon oxide (SiO _x ), silicon nitride (SiN _x ), silicon carbide (SiC), chromium nitride, silicon carbide (SiCN), silicon oxynitride (SiON), aluminum oxide (Al ₂ O). ₃ ), zirconium oxide (ZrO _x ), magnesium oxide (MgO), aluminum nitride (AlN) and the like.

FIG. 3 is a cross-sectional view of the magnetoresistive effect element 100. FIG. 3 is a cross section of the magnetoresistive effect element 100 cut in the xz plane passing through the center of the width of the spin-orbit torque wiring 20 in the y direction. FIG. 4 is a plan view of the magnetoresistive effect element 100 as viewed from the z direction.

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 laminated body 10 is laminated on the spin-orbit torque wiring 20. Another layer may be provided 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. Another layer may be provided between each of the first conductive layer 31 and the second conductive layer 32 and the spin-orbit torque wiring 20. The first conductive layer 31 and the second conductive layer 32 are located at positions sandwiching the laminated body 10 when viewed from the z direction.

The resistance value of the laminated body 10 in the z direction changes when spin is injected into the laminated body 10 from the spin track torque wiring 20. The magnetoresistive effect element 100 is a magnetic element using spin orbit torque (SOT), and may be referred to as a spin orbit torque type magnetoresistive element, a spin injection type magnetoresistive element, or a spin current magnetic resistance effect element. ..

The laminated body 10 is sandwiched between the spin-orbit torque wiring 20 and the electrode E (see FIG. 2) in the z direction. The laminated body 10 is a columnar body. The plan view shape of the laminated body 10 from the z direction is, for example, a circle, an ellipse, or a quadrangle. The side surface of the laminated body 10 is inclined with respect to the z direction, for example.

The laminated body 10 has, 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, the spin-orbit torque wiring 20 and is laminated on the 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 receives spin-orbit torque (SOT) due to the injected spin, and the orientation direction changes. The first ferromagnetic layer 1 and the second ferromagnetic layer 2 sandwich the non-magnetic layer 3 in the z direction.

The first ferromagnetic layer 1 and the second ferromagnetic layer 2 each have magnetization. The magnetization of the second ferromagnetic layer 2 is less likely to change in the orientation direction than the magnetization of the first ferromagnetic layer 1 when a predetermined external force is applied. The first ferromagnetic layer 1 is sometimes referred to as a magnetization free layer, and the second ferromagnetic layer 2 is sometimes referred to as a magnetization fixed layer or a magnetization reference layer. In the laminated body 10 shown in FIG. 3, the magnetization fixing layer is on the side away from the substrate Sub, and is called a top pin structure. The resistance value of the laminated body 10 changes according to the difference in the relative angles of magnetization between the first ferromagnetic layer 1 and the second ferromagnetic layer 2 sandwiching the non-magnetic layer 3.

The first ferromagnetic layer 1 and the second ferromagnetic layer 2 include a ferromagnet. The ferromagnet 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, and at least one of these metals and B, C, and N. It is an alloy containing the element of. 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.

The first ferromagnetic layer 1 and the second ferromagnetic layer 2 may contain a Whistler alloy. Whisler alloys include intermetallic compounds with a chemical composition of XYZ or _X2YZ . X is a transition metal element or noble metal element of Group Co, Fe, Ni, or Cu on the periodic table, Y is a transition metal of Group Mn, V, Cr, or Ti, or an elemental species of X, and Z is Group III. It is a typical element of Group V. The Whisler alloy is, for example, Co ₂ FeSi, Co ₂ FeGe, Co ₂ FeGa, Co ₂ MnSi, Co ₂ Mn _1-a Fe _a Al _b Si _1-b , Co ₂ FeGe _1-c Ga _c and the like. Whisler alloys have a high spin polarizability.

The non-magnetic layer 3 contains a non-magnetic material. When the non-magnetic layer 3 is an insulator (when it is a tunnel barrier layer), for example, Al ₂ O ₃ , SiO ₂ , MgO, MgAl ₂ O ₄ and the like can be used as the material thereof. In addition to these, a material or the like in which a part of Al, Si, and Mg is replaced with Zn, Be, or the like can also be used. Among these, _MgO and _MgAl2O4 are materials that can realize a coherent tunnel, so that spin can be efficiently injected. When the non-magnetic layer 3 is a metal, Cu, Au, Ag or the like can be used as the material. Further, when the non-magnetic layer 3 is a semiconductor, Si, Ge, CuInSe ₂ , CuGaSe ₂ , Cu (In, Ga) Se ₂ and the like can be used as the material.

The laminated body 10 may have a layer other than the first ferromagnetic layer 1, the second ferromagnetic layer 2, and the non-magnetic 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 enhances the crystallinity of each layer constituting the laminated body 10. Further, for example, the cap layer may be provided on the uppermost surface of the laminated body 10.

Further, the laminated body 10 may be provided with a ferromagnetic layer via a spacer layer on the surface of the second ferromagnetic layer 2 opposite to the non-magnetic layer 3. The second ferromagnetic layer 2, the spacer layer, and the ferromagnetic layer have a synthetic antiferromagnetic structure (SAF structure). The synthetic antiferromagnetic structure consists of two magnetic layers sandwiching the non-magnetic layer. The antiferromagnetic coupling between the second ferromagnetic layer 2 and the ferromagnetic layer increases the coercive force of the second ferromagnetic layer 2 as compared with the case without the ferromagnetic layer. The ferromagnetic layer is, for example, IrMn, PtMn or the like. The spacer layer contains, for example, at least one selected from the group consisting of Ru, Ir, Rh.

For example, the spin-orbit torque wiring 20 has a length in the x direction longer than the y direction when viewed from the z direction, and extends in the x direction. The write current flows in the x direction of the spin-orbit torque wiring 20. At least a part of the spin-orbit torque wiring 20 sandwiches the first ferromagnetic layer 1 together with the non-magnetic layer 3 in the z direction.

The spin-orbit torque wiring 20 generates a spin current by the spin Hall effect when the current I flows, and injects spin into the first ferromagnetic layer 1. The spin-orbit torque wiring 20 gives, for example, a spin-orbit torque (SOT) sufficient to reverse the magnetization of the first ferromagnetic layer 1 to the magnetization of the first ferromagnetic layer 1. The spin Hall effect is a phenomenon in which a spin current is induced in a direction orthogonal to the direction in which a current flows, based on the spin-orbit interaction when a current is passed. The spin Hall effect is common to the normal Hall effect in that the moving (moving) charge (electron) can bend the moving (moving) direction. In the normal Hall effect, the direction of motion of charged particles moving in a magnetic field is bent by Lorentz force. On the other hand, in the spin Hall effect, even in the absence of a magnetic field, the direction of spin movement is bent only by the movement of electrons (only the flow of current).

For example, when a current flows through the spin-orbit torque wiring 20, the first spin oriented in one direction and the second spin oriented in the direction opposite to the first spin spin in directions orthogonal to the direction in which the current I flows. It is bent by the Hall effect. For example, the first spin oriented in the −y direction is bent in the + z direction, and the second spin oriented in the + y direction is bent in the −z direction.

In a non-magnetic material (material that is not a ferromagnet), the number of electrons in the first spin and the number of electrons in the second spin generated by the spin Hall effect are equal. That is, the number of electrons in the first spin in the + z direction is equal to the number of electrons in the second spin in the −z direction. The first spin and the second spin flow in the direction of eliminating the uneven distribution of spins. In the movement of the first spin and the second spin in the z direction, the charge flows cancel each other out, so that the amount of current becomes zero. Spin currents without current are especially called pure spin currents.

When the electron flow of the first spin is J _↑ , the electron flow of the second spin is J _↓ , and the spin flow is J _S , it is defined as J _S = J _↑ -J _↓ . The spin current _JS occurs in the z direction. The first spin is injected into the first ferromagnetic layer 1 from the spin-orbit torque wiring 20.

The spin-orbit torque wiring 20 contains a compound having a pyrochlore structure. The spin-orbit torque wiring 20 may be made of a compound having a pyrochlore structure.

The compound having a pyrochlore structure is, for example, an oxide, an oxynitride, a fluoride, or a hydroxide. The compound having a pyrochlore structure is, for example, an oxide. Oxides are easy to handle. In addition, oxides with a pyrochlore structure have higher electrical resistivity than metals. When a high voltage can be applied between the first conductive layer 31 and the second conductive layer 32, the efficiency of injecting spins from the spin-orbit torque wiring 20 into the first ferromagnetic layer 1 is increased.

The oxide represented by the composition formula of R ₂ Ir ₂ O ₇ is an example of an oxide having a pyrochlore structure. R in the composition formula is one or more elements selected from the group consisting of Pr, Nd, Sm, Eu, Gd, Tb, Dy and Ho. Although the above composition formula is described as a stoichiometric composition, deviation from the stoichiometric composition is allowed within a range in which the crystal structure can be maintained. For example, oxides with a pyrochlore structure may be oxygen deficient. The conductivity of the spin-orbit torque wiring 20 can be adjusted according to the degree of oxygen deficiency.

FIG. 5 is a diagram showing a crystal structure of a pyrochlore structure. FIG. 5 is a crystal structure of Nd ₂ Ir ₂ O ₇ . In FIG. 5, oxygen is omitted. The pyrochlore structure is a structure in which two cations (Nd ion and Ir ion) are arranged along the plane orientation <110>. The pyrochlore structure has a structure in which R atoms form a regular tetrahedron, and the regular tetrahedrons are three-dimensionally connected while sharing vertices.

In a regular tetrahedron with a pyrochlore structure, magnetic frustration occurs when the magnetic interaction between the closest atoms is antiferromagnetic. Magnetic frustration disrupts the magnetic balance within a substance and increases spin fluctuations. The pyrochlore structure does not have a long-range correlation between magnetic ions at room temperature, and has paramagnetism or magnetic properties similar to paramagnetism.

The spin-orbit torque wiring 20 having a compound having a pyrochlore structure can generate a large spin current. It is considered that the magnetic frustration disturbs the symmetry in the spin-orbit torque wiring 20, so that a strong spin-orbit interaction occurs between the conduction electron and the localized electron.

R in the composition formula may contain at least one element of Pr and Nd. These elements are referred to as first elements. The pyrochlore structure containing the first element has a lower electrical resistivity than the case where R in the composition formula is another element. Therefore, the operating voltage of the magnetoresistive effect element 100 can be lowered.

In addition, the pyrochlore structure containing the first element has a resistance value that behaves like a metal with respect to temperature. The metallic behavior of the resistance value is that the higher the temperature, the larger the resistance value. In this case, the higher the temperature of the spin-orbit torque wiring 20, the more difficult it is for the current to flow. In other words, the amount of spin injected from the spin-orbit torque wiring 20 into the first ferromagnetic layer 1 decreases as the temperature rises. By the way, the magnetization of the first ferromagnetic layer 1 is more likely to be reversed as the temperature is higher. If the amount of spin injected into the first ferromagnetic layer 1 is small at a high temperature at which magnetization reversal is likely to occur, and the amount of spin injected into the first ferromagnetic layer 1 at a low temperature at which magnetization reversal is difficult is large, the magnetoresistive sensor 100 as a whole The temperature dependence of is small.

Further, R in the composition formula may contain a first element and one or more elements selected from the group consisting of Sm, Eu, Gd, Tb, Dy and Ho. One or more elements selected from the group consisting of Sm, Eu, Gd, Tb, Dy and Ho are referred to as a second element.

The pyrochlore structure containing the second element has a resistance value that behaves like a semiconductor with respect to temperature. The semiconductor behavior of the resistance value is that the resistance value decreases as the temperature rises.

When the compound having a pyrochlor structure has both the first element and the second element, the metallic behavior and the semiconductor-like behavior of the resistance value cancel each other out, and the influence of the temperature on the spin-orbit torque wiring 20 is reduced. ..

Further, the composition ratio of the second element contained in the pyrochlore structure is smaller than, for example, the composition ratio of the first element. In this case, the resistance value of the spin-orbit torque wiring 20 exhibits metallic behavior with respect to temperature. By including the second element, the spin-orbit torque wiring 20 can avoid exhibiting an extreme metallic behavior in resistance value. Further, as the magnetoresistive element 100 as a whole, the spin-orbit torque wiring 20 exhibits metallic behavior, so that the temperature dependence becomes small.

The electrical resistivity of the spin-orbit torque wiring 20 is, for example, 1 mΩ · cm or more. The electrical resistivity of the spin-orbit torque wiring 20 is, for example, 10 mΩ · cm or less. When the electrical resistivity of the spin-orbit torque wiring 20 is high, a high voltage can be applied to the spin-orbit torque wiring 20. When the potential of the spin-orbit torque wiring 20 becomes high, spin can be efficiently supplied from the spin-orbit torque wiring 20 to the first ferromagnetic layer 1. Further, since the spin-orbit torque wiring 20 has a certain level of conductivity or more, a current path flowing along the spin-orbit torque wiring 20 can be secured, and a spin flow associated with the spin Hall effect can be efficiently generated.

The thickness of the spin-orbit torque wiring 20 is, for example, 4 nm or more. The thickness of the spin-orbit torque wiring 20 may be, for example, 20 nm or less.

When the spin-orbit torque wiring 20 is made of metal, by reducing the thickness of the spin-orbit torque wiring 20, a current having a current density equal to or higher than the inverting current density can flow along the spin-orbit torque wiring 20. However, it is difficult to form a thinner film more uniformly. The inverting current density is the current density required to reverse the magnetization of the magnetoresistive effect element 100, and the magnetoresistive sensor 100 operates by reversing the magnetization.

On the other hand, when the electrical resistivity of the spin track torque wiring 20 is high, the current density of the current flowing along the spin track torque wiring 20 can be made higher than the inverting current density even if the spin track torque wiring 20 is thick. When the spin-orbit torque wiring 20 is thick, the spin-orbit torque wiring 20 can be easily formed uniformly, and the variation among the plurality of magnetoresistive elements 100 can be reduced.

The spin-orbit torque wiring 20 may also contain a magnetic metal or a topological insulator. A topological insulator is a substance in which the inside of the substance is an insulator or a high resistance substance, but a metallic state in which spin polarization occurs on the surface thereof.

Each of the first conductive layer 31 and the second conductive layer 32 is an example of the conductive layer. Each of the first conductive layer 31 and the second conductive layer 32 is made of a material having excellent conductivity. The first conductive layer 31 and the second conductive layer 32 are, for example, Al, Cu, W, and Cr.

Next, a method for manufacturing the magnetoresistive sensor 100 will be described. The magnetoresistive sensor 100 is formed by a laminating step of each layer and a processing step of processing a part of each layer into a predetermined shape. For the lamination of each layer, a sputtering method, a chemical vapor deposition (CVD) method, an electron beam vapor deposition method (EB vapor deposition method), an atomic laser deposit method, or the like can be used. The processing of each layer can be performed by using photolithography or the like.

First, impurities are doped at a predetermined position on the substrate Sub to form the source S and the 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 serve as a transistor Tr.

Next, the insulating layer In is formed so as to cover the transistor Tr. Further, by forming an opening in the insulating layer In and filling the opening with a conductor, the via wiring V, the first conductive layer 31 and the second conductive layer 32 are formed. The write wiring WL and the common wiring CL are formed by laminating the insulating layer In to a predetermined thickness, forming a groove in the insulating layer In, and filling the groove with a conductor.

Next, an oxide layer is laminated on one surface of the insulating layer In, the first conductive layer 31 and the second conductive layer 32. The step of forming an oxide layer is referred to as a first film forming step. The oxide layer contains an oxide having a pyrochlore structure. In the first film forming step, the metal is DC sputtered at the same time as or after the RF sputtering of the oxide. The first film forming step is performed, for example, in an oxygen atmosphere. By adjusting the oxygen partial pressure, the composition ratio of oxygen in the oxide of the pyrochlore structure can be adjusted.

The RF sputtering oxide is, for example, R ₂ O ₃ (R is one or more elements selected from the group consisting of Pr, Nd, Sm, Eu, Gd, Tb, Dy and Ho). The metal sputtered by DC is, for example, Ir. By migrating the target oxide and metal on the film-deposited surface, an oxide layer containing an oxide having a pyrochlore structure can be obtained.

Next, the ferromagnetic layer, the non-magnetic layer, the ferromagnetic layer, and the hard mask layer are laminated in order on the oxide layer. Next, 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 oxide layer, the ferromagnetic layer, the non-magnetic layer, and the ferromagnetic layer are processed into a predetermined shape at once via the hard mask layer. The oxide layer is processed into a predetermined shape to form a spin-orbit torque wiring 20.

Next, the unnecessary part of the hard mask layer in the x direction is removed. The hard mask layer has the outer shape of the laminated body 10. Next, the unnecessary portion in the x direction of the laminate formed on the spin-orbit torque wiring 20 is removed via the hard mask layer. The laminated body 10 is processed into a predetermined shape to become the laminated body 10. The hard mask layer serves as an electrode E. Next, the periphery of the laminated body 10 and the spin-orbit torque wiring 20 is filled with the insulating layer In to obtain the magnetoresistive element 100.

The magnetoresistive effect element 100 according to the first embodiment can efficiently generate a spin current in the spin-orbit torque wiring 20, and efficiently spins from the spin-orbit torque wiring 20 to the first ferromagnetic layer 1. Can be injected into. Therefore, the magnetoresistive element 100 according to the first embodiment can reduce the amount of write current required to reverse the magnetization of the first ferromagnetic layer 1. When the amount of write current of each element is small, the power consumption of the entire magnetic memory 200 can be reduced.

This is because the spin-orbit torque wiring 20 has a pyrochlore structure. The magnetic frustration that occurs in the pyrochlor structure disturbs the symmetry in the spin-orbit torque wiring 20 and efficiently creates a spin current in the spin-orbit torque wiring 20. The generated spin current is efficiently injected into the first ferromagnetic layer 1 according to the potential difference between the spin-orbit torque wiring 20 and the first ferromagnetic layer 1.

Although an example of the magnetoresistive sensor 100 according to the first embodiment has been shown above, it is possible to add, omit, replace, and otherwise change the configuration within a range that does not deviate from the gist of the present invention.

(First modification)
FIG. 6 is a cross-sectional view of the magnetoresistive effect element 101 according to the first modification. FIG. 6 is an xz cross section passing through the center of the spin-orbit torque wiring 20 in the y direction. In FIG. 6, the same components as those in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted.

The magnetoresistive element 101 according to the first modification 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, on the spin-orbit torque wiring 20.

The first intermediate layer 40 contains a heavy metal of a non-magnetic layer. Heavy metals are metals having an atomic number (specific gravity) of yttrium (Y) or higher. The non-magnetic heavy metal is, for example, a non-magnetic metal having a d-electron or an f-electron in the outermost shell and having an atomic number of 39 or more and a large atomic number. The first intermediate layer 40 includes, for example, any one or more of Au, Bi, Hf, Ir, Mo, Pd, Pt, Rh, Ru, Ta, and W. The main element of the first intermediate layer 40 is preferably, for example, any of these elements.

The first intermediate layer 40 does not have to be a completely continuous layer, and may be, for example, a continuous film having a plurality of openings or a layer containing a plurality of components scattered in an island shape.

The thickness of the first intermediate layer 40 is, for example, less than or equal to the spin diffusion length of the substance constituting the layer. The thickness of the first intermediate layer 40 is, for example, five times or less the bond radius of the elements constituting the first intermediate layer 40. The bond radius is a value that is half the distance between the re-adjacent atoms of the crystal of the element constituting the first intermediate layer 40. Since the thickness of the first intermediate layer 40 is thin, it is possible to suppress the spin generated in the spin-orbit torque wiring 20 from diffusing before reaching the first ferromagnetic layer 1.

The first intermediate layer 40 is formed in the second film forming step. The second film forming step is performed after the first film forming step. The second film forming step is a step of forming a heavy metal layer containing a heavy metal having an atomic number larger than that of yttrium on the oxide layer formed in the first film forming step.

The gas pressure in the chamber in the second film forming step is, for example, higher than the gas pressure in the chamber in the first film forming step. That is, the degree of vacuum in the second film forming step is made worse than that in the first film forming step.

If the degree of vacuum in the second film formation step is low, non-magnetic heavy metals will grow. When the non-magnetic heavy metal grows in grains, the first intermediate layer 40 becomes a continuous film having a plurality of openings or a layer containing a plurality of components scattered in an island shape. In this case, the spin-orbit torque wiring 20 and the first ferromagnetic layer 1 are partially in direct contact with each other, and the first intermediate layer is formed before the spin generated by the spin-orbit torque wiring 20 reaches the first ferromagnetic layer 1. It is possible to further suppress the diffusion at 40.

The write current flows along the wiring in which the first intermediate layer 40 and the spin-orbit torque wiring 20 are combined. The write current flowing through the wiring is divided into the first intermediate layer 40 and the spin-orbit torque wiring 20. By dividing a part of the current, it is possible to suppress heat generation in the spin-orbit torque wiring 20 in which the current is difficult to flow. Moreover, the resistance of the wiring as a whole can be reduced.

Further, the non-magnetic heavy metal constituting the first intermediate layer 40 has a stronger spin-orbit interaction than other metals. Therefore, the write current flowing in the first intermediate layer 40 also produces a spin current.

Further, when the first intermediate layer 40 is provided, an interface of different substances is formed between the first intermediate layer 40 and the spin-orbit torque wiring 20. At the interface between different substances, the Rashba effect occurs and the amount of spin injected into the first ferromagnetic layer 1 increases.

(Second modification)
FIG. 7 is a cross-sectional view of the magnetoresistive effect element 102 according to the second modification. FIG. 7 is an xz cross section passing through the center of the spin-orbit torque wiring 20 in the y direction. In FIG. 7, the same components as those in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted.

The magnetoresistive element 102 according to the first modification 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, on the spin-orbit torque wiring 20.

The second intermediate layer 50 contains one or more elements selected from the group consisting of Cu, Al, Si and Al. The second intermediate layer 50 is made of one or more elements selected from the group consisting of, for example, Cu, Al, Si and Al. These elements are excellent in conductivity. Therefore, the resistance of the entire wiring of the second intermediate layer 50 and the spin-orbit torque wiring 20 can be further reduced. In addition, these elements have a long spin diffusion length. Therefore, the second intermediate layer 50 is difficult to diffuse the spin. The spin generated in the spin-orbit torque wiring 20 is efficiently supplied to the first ferromagnetic layer 1 even through the second intermediate layer 50.

The second intermediate layer 50 does not have to be a completely continuous layer, and may be, for example, a continuous film having a plurality of openings or a layer containing a plurality of components scattered in an island shape. The thickness of the second intermediate layer 50 is, for example, equal to or less than the spin diffusion length of the substance constituting the layer.

The second intermediate layer 50 is formed in the third film forming step. The third film forming step is performed after the first film forming step. The third film forming step is a step of forming a layer containing one or more elements selected from the group consisting of Cu, Al, Si and Al on the oxide layer formed in the first forming step. Is.

The write current flows along the wiring in which the second intermediate layer 50 and the spin-orbit torque wiring 20 are combined. The write current flowing through the wiring is divided into the second intermediate layer 50 and the spin-orbit torque wiring 20. By dividing a part of the current, it is possible to suppress heat generation in the spin-orbit torque wiring 20 in which the current is difficult to flow. Moreover, the resistance of the wiring as a whole can be reduced.

Further, when the second intermediate layer 50 is provided, an interface of different substances is formed between the second intermediate layer 50 and the spin-orbit torque wiring 20. At the interface between different substances, the Rashba effect occurs and the amount of spin injected into the first ferromagnetic layer 1 increases.

(Third modification example)
FIG. 8 is a cross-sectional view of the magnetoresistive effect element 103 according to the third modification. FIG. 8 is an xz cross section passing through the center of the spin-orbit torque wiring 20 in the y direction. In FIG. 8, the same components as those in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted.

The magnetoresistive element 103 according to the third modification has a first intermediate layer 40 and a second intermediate layer 50 between the spin-orbit torque wiring 20 and the first ferromagnetic layer 1. The first intermediate layer 40 and the second intermediate layer 50 each have one or more layers. The first intermediate layer 40 and the second intermediate layer 50 are laminated alternately, for example. The stacking order of the first intermediate layer 40 and the second intermediate layer 50 does not matter. When the layer in contact with the first ferromagnetic layer 1 is the first intermediate layer 40, the spin generated in the first intermediate layer 40 can be efficiently injected into the first ferromagnetic layer 1.

The first intermediate layer 40 is the same as the first modification. The second intermediate layer 50 is the same as that of the second modification. The number of layers of the first intermediate layer 40 and the second intermediate layer 50 does not matter. The first intermediate layer 40 and the second intermediate layer 50 are formed by repeating the second film forming step and the third film forming step after the first film forming step. These layers are formed on the oxide layer formed in the first film forming step.

By having the first intermediate layer 40 and the second intermediate layer 50, the magnetoresistive effect element 103 can reduce the resistance of the wiring as a whole. Further, since there are a plurality of different types of interfaces between the first ferromagnetic layer 1 and the spin-orbit torque wiring 20, the amount of spin injected into the first ferromagnetic layer 1 can be increased due to the Rashba effect.

(Fourth modification)
FIG. 9 is a cross-sectional view of the magnetoresistive effect element 104 according to the fourth modification. FIG. 9 is an xz cross section passing through the center of the spin-orbit torque wiring 20 in the y direction. In FIG. 9, the same components as those in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted.

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

The magnetoresistive sensor 104 according to the fourth modification is different only in the positional relationship of each configuration, and the same effect as the magnetoresistive element 100 according to the first embodiment can be obtained.

"Second embodiment"
FIG. 10 is a cross-sectional view of the magnetization rotating element 105 according to the second embodiment. In FIG. 1, the magnetization rotating element 105 is replaced with the magnetoresistive effect element 100 according to the first embodiment.

The magnetizing rotating element 105, for example, incidents light on 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-optic Kerr effect, the deflection state of the reflected light changes. The magnetization rotating element 105 can be used, for example, as an optical element for, for example, an image display device that utilizes a difference in the deflection state of light.

In addition, the magnetization rotating element 105 can be used alone as an anisotropic magnetic sensor, an optical element utilizing the magnetic Faraday effect, and the like.

The spin-orbit torque wiring 20 of the magnetizing rotating element 105 has a compound having a pyrochlore structure.

In the magnetization rotating element 105 according to the second embodiment, only the non-magnetic layer 3 and the second ferromagnetic layer 2 are removed from the magnetoresistive effect element 100, and the magnetoresistive element 100 according to the first embodiment is used. A similar effect can be obtained.

Up to this point, preferred embodiments of the present invention have been exemplified based on the first embodiment, the second embodiment, and modifications, but the present invention is not limited to these embodiments. For example, the characteristic configurations in each embodiment and modification may be applied to other embodiments and modifications.

1 ... 1st ferromagnetic layer, 2 ... 2nd ferromagnetic layer, 3 ... non-magnetic layer, 10 ... laminate, 20 ... spin track torque wiring, 31 ... first conductive layer, 32 ... second conductive layer, 40 ... 1st intermediate layer, 50 ... 2nd intermediate layer, 100, 101, 102, 103, 104 ... Magnetic resistance effect element, 105 ... Magnetized rotating element, 200 ... Magnetic memory, CL ... Common wiring, RL ... Read wiring, WL ... Write wiring, In ... Insulation layer

Claims

Spin-orbit torque wiring and
A first ferromagnetic layer laminated on the spin-orbit torque wiring is provided.
The spin-orbit torque wiring is a magnetized rotating element containing a compound having a pyrochlore structure.
The magnetization rotating element according to claim 1, wherein the compound is an oxide.
The oxide is represented by the composition formula of R 2 Ir 2 O 7 in the stoichiometric composition.
The magnetization rotating element according to claim 2, wherein R in the composition formula is one or more elements selected from the group consisting of Pr, Nd, Sm, Eu, Gd, Tb, Dy and Ho.
R in the composition formula contains the first element and contains.
The magnetization rotating element according to claim 3, wherein the first element is at least one of Pr and Nd.
R in the composition formula includes a first element and a second element, and contains.
The first element is at least one of Pr and Nd, and is
The magnetization rotating element according to claim 4, wherein the second element is one or more elements selected from the group consisting of Sm, Eu, Gd, Tb, Dy and Ho.
The magnetization rotating element according to claim 5, wherein the composition ratio of the second element is smaller than the composition ratio of the first element.
The magnetization rotating element according to any one of claims 2 to 6, wherein the oxide is oxygen-deficient.
The magnetized rotating element according to any one of claims 1 to 7, wherein the spin-orbit torque wiring has an electrical resistivity of 1 mΩ · cm or more.
The magnetized rotating element according to any one of claims 1 to 8, wherein the spin-orbit torque wiring has an electrical resistivity of 10 mΩ · cm or less.
A first intermediate layer is provided between the first ferromagnetic layer and the spin-orbit torque wiring.
The magnetization rotating element according to any one of claims 1 to 9, wherein the first intermediate layer contains a heavy metal having an atomic number larger than that of yttrium.
A second intermediate layer is provided between the first ferromagnetic layer and the spin-orbit torque wiring.
The magnetization rotating element according to any one of claims 1 to 10, wherein the second intermediate layer contains one or more elements selected from the group consisting of Cu, Al, Si and Al.
A first intermediate layer and a second intermediate layer are provided between the first ferromagnetic layer and the spin-orbit torque wiring, respectively.
The first intermediate layer contains a heavy metal having an atomic number larger than that of yttrium.
The magnetization rotating element according to any one of claims 1 to 11, wherein the second intermediate layer contains one or more elements selected from the group consisting of Cu, Al, Si and Al.
The magnetizing rotating element according to any one of claims 1 to 12,
A non-magnetic layer in contact with the first ferromagnetic layer of the magnetization rotating element,
A magnetoresistive sensor comprising the first ferromagnetic layer and a second ferromagnetic layer sandwiching the non-magnetic layer.
A magnetic memory provided with a plurality of magnetoresistive elements according to claim 13.
A method for manufacturing wiring, which comprises a first film forming step of forming an oxide layer containing a pyrochlore structure by DC sputtering of a metal at the same time as or after RF sputtering of an oxide.
The oxide is R 2 O 3 (R is one or more elements selected from the group consisting of Pr, Nd, Sm, Eu, Gd, Tb, Dy and Ho).
The method for manufacturing wiring according to claim 15, wherein the metal is Ir.
The method for manufacturing wiring according to claim 15 or 16, wherein the first film forming step is performed in an oxygen atmosphere.
After the first film forming step, there is a second film forming step of forming a heavy metal layer containing a heavy metal having an atomic number larger than that of yttrium.
The method for manufacturing wiring according to any one of claims 15 to 17, wherein the gas pressure in the second film forming step is higher than the gas pressure in the first film forming step.
A second film forming step for forming a heavy metal layer containing a heavy metal having an atomic number larger than that of yttrium, and
A third film forming step for forming a layer containing one or more elements selected from the group consisting of Cu, Al, Si and Al is further provided after the first film forming step.
The method for manufacturing wiring according to any one of claims 15 to 17, wherein the second film forming step and the third film forming step are alternately performed.