Magnetoresistive effect element manufacturing method, magnetoresistive effect element, magnetic laminated film, magnetic memory, and magnetic sensor

Abstract

To provide a magnetoresistive element, a magnetic memory, and a magnetic sensor that are resistant to the influence of external forces such as heat and external magnetic fields and have high magnetization stability.SOLUTION: A magnetoresistive element includes a first ferromagnetic layer, a second ferromagnetic layer, a non-magnetic layer, and an underlayer. The non-magnetic layer is located between the first ferromagnetic layer and the second ferromagnetic layer. The first ferromagnetic layer is located between the underlayer and the non-magnetic layer. The underlayer contains Ta. The first ferromagnetic layer is expressed as CoαFeβXγPtδ, where X is boron or carbon, and α+β+γ+δ=1, α≥β>0, and δ≤0.3 are satisfied. The easy axis of magnetization of the first ferromagnetic layer is a first in-plane direction perpendicular to a stacking direction, and the anisotropy field of the first ferromagnetic layer in a second direction is 50 Oe or more. The second direction is perpendicular to the stacking direction and the first direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a magnetoresistive element, a magnetoresistive element, a magnetic laminated film, a magnetic memory, and a magnetic sensor. [Background technology]

[0002] A magnetoresistive element is an element whose resistance value changes in the stacking direction due to the magnetoresistive effect. A magnetoresistive element includes two ferromagnetic layers and a non-magnetic layer sandwiched between them. A magnetoresistive element that uses a conductor for the non-magnetic layer is called a giant magnetoresistive (GMR) element, and a magnetoresistive element that uses an insulating layer (tunnel barrier layer, barrier layer) for the non-magnetic layer is called a tunneling magnetoresistive (TMR) element. Magnetoresistive elements can be used in a variety of applications, including magnetic sensors, high-frequency components, magnetic heads, and non-volatile random access memories (MRAMs).

[0003] The resistance value of a magnetoresistive element changes depending on the difference in the relative angle between the magnetization directions of two magnetic films. Magnetic memories record the resistance value of this magnetoresistive element as data. Magnetic sensors use changes in the resistance value of this magnetoresistive element for sensing. If the resistance value of the magnetoresistive element changes unexpectedly due to the influence of heat, an external magnetic field, or the like, this resistance change becomes noise in the magnetic memory or magnetic sensor. To reduce noise, attempts have been made to increase the magnetization stability of the magnetoresistive element.

[0004] For example, Patent Document 1 describes that uniaxial magnetic anisotropy of a magnetic material is increased by orienting the crystal grain orientation of a nanocrystalline soft magnetic material. Also, for example, Patent Document 2 describes that uniaxial magnetic anisotropy is increased by ordering an FePt alloy. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-118040 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-311925 Summary of the Invention [Problem to be solved by the invention]

[0006] The uniaxial magnetic anisotropy of a ferromagnetic layer is determined by various factors. For example, the magnetic anisotropy of a ferromagnetic layer is affected by factors such as the anisotropy caused by the shape of the ferromagnetic layer (shape magnetic anisotropy), the anisotropy caused by the influence of the interface between the ferromagnetic layer and an adjacent layer (interface magnetic anisotropy), the anisotropy caused by the crystalline structure of the ferromagnetic layer (magnetocrystalline anisotropy), and the anisotropy induced by a magnetic field during the growth of the ferromagnetic layer (induced magnetic anisotropy). Depending on the application of the magnetoresistive element, there may be restrictions on the shape, etc., making it difficult to impart shape magnetic anisotropy to the ferromagnetic layer.

[0007] The present disclosure has been made in consideration of the above circumstances, and aims to provide a magnetoresistive effect element, a magnetic laminated film, a magnetic memory, and a magnetic sensor that are less susceptible to external forces such as heat and external magnetic fields and have high magnetization stability, as well as methods for manufacturing these. [Means for solving the problem]

[0008] To solve the above problems, the present disclosure provides the following means.

[0009] (1) A method for manufacturing a magnetoresistive element according to a first aspect includes a lamination step of laminating an underlayer, a first ferromagnetic layer, a non-magnetic layer, and a second ferromagnetic layer in this order, and a magnetic field application annealing step of annealing while applying a magnetic field in a first direction in a plane perpendicular to the lamination direction. The underlayer contains Ta. The first ferromagnetic layer contains Co. α Fe β X γ Pt δ where X is boron or carbon, and satisfies α+β+γ+δ=1, α≧β>0, and δ≦0.3.

[0010] (2) In the method for manufacturing a magnetoresistive element according to the above aspect, the annealing temperature in the magnetic field application annealing step may be 200° C. or higher.

[0011] (3) In the method for manufacturing a magnetoresistive element according to the above aspect, the annealing time in the magnetic field application annealing step may be 30 minutes or more.

[0012] (4) In the magnetic field application annealing step of the method for manufacturing a magnetoresistive element according to the above aspect, the strength of the magnetic field applied may be 1 kOe or more.

[0013] (5) In the method for manufacturing a magnetoresistive element according to the above aspect, γ may satisfy 0.05≦γ≦0.2.

[0014] (6) In the method for manufacturing a magnetoresistive element according to the above aspect, δ may satisfy the relationship 0.05≦δ≦0.3.

[0015] (7) In the method for manufacturing a magnetoresistive element according to the above aspect, the nonmagnetic layer may contain magnesium and oxygen.

[0016] (8) A magnetoresistive element according to a second aspect includes a first ferromagnetic layer, a second ferromagnetic layer, a non-magnetic layer, and an underlayer. The non-magnetic layer is located between the first ferromagnetic layer and the second ferromagnetic layer. The first ferromagnetic layer is located between the underlayer and the non-magnetic layer. The underlayer contains Ta. The first ferromagnetic layer contains Co. α Fe β X γ Pt δ where X is boron or carbon, and satisfies α+β+γ+δ=1, α≧β>0, and δ≦0.3. The easy axis of the first ferromagnetic layer is a first direction in a plane perpendicular to the stacking direction, and the anisotropy field of the first ferromagnetic layer in a second direction is 50 Oe or more. The second direction is perpendicular to the stacking direction and the first direction.

[0017] (9) In the magnetoresistive element according to the above aspect, γ may satisfy the relationship 0.05≦γ≦0.2.

[0018] (10) In the magnetoresistive element according to the above aspect, δ may satisfy the relationship 0.05≦δ≦0.3.

[0019] (11) In the magnetoresistive element according to the above aspect, the nonmagnetic layer may contain magnesium and oxygen.

[0020] (12) In the magnetoresistive element according to the above aspect, the first ferromagnetic layer may have a thickness of 2 nm or more and 20 nm or less.

[0021] (13) In the magnetoresistive element according to the above aspect, the first ferromagnetic layer has a uniaxial magnetic anisotropy energy of 2.0×10 4 erg / cm or more is acceptable.

[0022] (14) The magnetoresistive effect element according to the above aspect may further include a first electrode and a second electrode, wherein the first electrode is connected to a first end of the base layer, and the second electrode is connected to a second end of the base layer that is different from the first end.

[0023] (15) In the magnetoresistive effect element according to the above aspect, when viewed in a plane from the stacking direction, the width in the first direction of the first ferromagnetic layer may be 90% or more and 110% or less of the width in the second direction of the first ferromagnetic layer.

[0024] (16) A magnetic laminated film according to a third aspect includes an underlayer and a first ferromagnetic layer. The underlayer is in contact with one surface of the first ferromagnetic layer. The underlayer contains Ta. The first ferromagnetic layer contains Co. α Fe β X γ Pt δwhere X is boron or carbon, and satisfies α+β+γ+δ=1, α≧β>0, 0.05≦γ≦0.2, and 0.05≦δ≦0.3. The easy axis of the first ferromagnetic layer is a first direction in a plane perpendicular to the stacking direction, and the anisotropy field of the first ferromagnetic layer in a second direction is 50 Oe or more. The second direction is perpendicular to the stacking direction and the first direction.

[0025] (17) A magnetic memory according to a fourth aspect includes the magnetoresistive element according to the above aspect.

[0026] (18) A magnetic sensor according to a fifth aspect includes the magnetoresistive element according to the above aspect. [Effects of the Invention]

[0027] The magnetoresistive element, magnetic laminated film, magnetic memory, and magnetic sensor according to the present disclosure can reduce the influence of external forces. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a cross-sectional view of a magnetoresistive effect element according to a first embodiment. [Figure 2] FIG. 1 is a plan view of a magnetoresistive effect element according to a first embodiment. [Figure 3] 3A to 3C are diagrams illustrating a method for manufacturing the magnetoresistive effect element according to the first embodiment. [Figure 4] 3A to 3C are diagrams illustrating a method for manufacturing the magnetoresistive effect element according to the first embodiment. [Figure 5] FIG. 2 is a circuit schematic diagram of the magnetic memory according to the embodiment. [Figure 6] 1 is a cross-sectional view of a magnetoresistive element used in a magnetic memory according to an embodiment of the present invention. [Figure 7] FIG. 10 is a circuit schematic diagram of another example of the magnetic memory according to the embodiment. [Figure 8] FIG. 1 is a schematic diagram of a magnetic sensor according to an embodiment of the present invention. [Figure 9] 1 is a schematic diagram of a magnetic laminated film according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0029] The present embodiment will be described in detail below with reference to the drawings as appropriate. The drawings used in the following description may show characteristic portions enlarged for the sake of clarity, and the dimensional ratios of each component may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto. Appropriate changes can be made within the scope of the effects of the present invention.

[0030] First, let us define the directions. The stacking direction of each layer is the Z direction. The direction in the plane perpendicular to the Z direction is the X direction. The X direction is an example of the first direction. The direction perpendicular to the Z direction and the X direction is the Y direction. The Y direction is an example of the second direction. Regarding the Z direction, the direction from the underlayer to the first ferromagnetic layer is the +Z direction, and the opposite direction is the -Z direction. Hereinafter, the +Z direction may be expressed as "up" and the -Z direction as "down". Up and down do not necessarily coincide with the direction in which gravity is applied.

[0031] "Magnetoresistive element" 1 is a cross-sectional view of a magnetoresistive element 10 according to the first embodiment. The magnetoresistive element 10 has a first ferromagnetic layer 1, a second ferromagnetic layer 2, a non-magnetic layer 3, and an underlayer 4.

[0032] The magnetoresistive element 10 outputs a change in the relative angle between the magnetization of the first ferromagnetic layer 1 and the magnetization of the second ferromagnetic layer 2 as a change in resistance value or a change in output voltage. The magnetization of the first ferromagnetic layer 1 is, for example, more mobile than the magnetization of the second ferromagnetic layer 2. When a predetermined external force is applied, the direction of the magnetization of the second ferromagnetic layer 2 remains unchanged (is fixed), but the direction of the magnetization of the first ferromagnetic layer 1 changes. The resistance value of the magnetoresistive element 10 changes as the direction of the magnetization of the first ferromagnetic layer 1 changes relative to the direction of the magnetization of the second ferromagnetic layer 2. In this case, the second ferromagnetic layer 2 may be referred to as a magnetization fixed layer, and the first ferromagnetic layer 1 may be referred to as a magnetization free layer. In the following description, the second ferromagnetic layer 2 is described as a magnetization fixed layer and the first ferromagnetic layer 1 as a magnetization free layer, but this relationship may be reversed.

[0033] The difference in the mobility of the magnetization of the first ferromagnetic layer 1 and the magnetization of the second ferromagnetic layer 2 when a predetermined external force is applied is caused by the difference in the coercive force between the first ferromagnetic layer 1 and the second ferromagnetic layer 2. For example, if the thickness of the second ferromagnetic layer 2 is greater than that of the first ferromagnetic layer 1, the coercive force of the second ferromagnetic layer 2 is often greater than that of the first ferromagnetic layer 1. Furthermore, for example, by forming the second ferromagnetic layer 2 into a synthetic antiferromagnetic structure (SAF structure), the coercive force of the second ferromagnetic layer 2 can be made greater than that of the first ferromagnetic layer 1. A synthetic antiferromagnetic structure consists of two magnetic layers sandwiching a spacer layer. When the two magnetic layers sandwiching the spacer layer are antiferromagnetically coupled, the coercive force of the magnetic layer becomes greater than when they are not antiferromagnetically coupled. The spacer layer may contain at least one element selected from the group consisting of Ru, Ir, and Rh.

[0034] The first ferromagnetic layer 1 is located between the underlayer 4 and the non-magnetic layer 3. The first ferromagnetic layer 1 is made of Co α Fe β X γ Pt δ The ferromagnetic layer satisfies α+β+γ+δ=1. Co α Fe β X γ Pt δ The first ferromagnetic layer 1 has an induced magnetic anisotropy in the in-plane direction. The first ferromagnetic layer 1 has, for example, a cubic crystal (bcc) structure.

[0035] α represents the composition ratio of Co, and β represents the composition ratio of Fe. α and β satisfy the relationship α≧β>0. When α>β, the first ferromagnetic layer 1 becomes a Co-rich ferromagnetic layer. Co is a material that tends to have a hexagonal crystal structure and is more likely to exhibit uniaxial anisotropy than Fe, which tends to have a cubic crystal structure. Therefore, a first ferromagnetic layer 1 whose Co composition ratio is richer than that of Fe has a larger uniaxial magnetic anisotropy.

[0036] X is boron (B) or carbon (C), and is preferably boron (B). γ represents the composition ratio of X. γ preferably satisfies the relationship 0.05≦γ≦0.2. When γ satisfies this range, the lattice matching between the first ferromagnetic layer 1 and the nonmagnetic layer 3 is high, and the uniaxial magnetic anisotropy of the first ferromagnetic layer 1 is increased. The lattice matching between the first ferromagnetic layer 1 and the nonmagnetic layer 3 is, for example, within 10%, preferably within 5%. The lattice matching represents the degree of difference in the lattice constant of one of the two layers sandwiching the interface when the lattice constant of the other is used as a reference. The lower the lattice matching, the higher the lattice matching between the two layers sandwiching the interface. When the lattice constant of the nonmagnetic layer 3 is used as a reference, the lattice constant of the first ferromagnetic layer 1 is, for example, 90% to 110% of the lattice constant of the nonmagnetic layer 3.

[0037] δ represents the composition ratio of Pt. δ≦0.3 is satisfied. δ=0 is also acceptable. When δ=0, the first ferromagnetic layer 1 is composed of Co. α Fe β X γ It is expressed as follows. It is preferable that δ satisfies 0.05≦δ≦0.3. When δ>0, the uniaxial magnetic anisotropy of the first ferromagnetic layer 1 becomes large. It is believed that the uniaxial magnetic anisotropy of the first ferromagnetic layer 1 becomes large because the first ferromagnetic layer 1 contains Pt, which has a large spin-orbit coupling.

[0038] The first ferromagnetic layer 1 has an easy axis of magnetization in the X direction. The anisotropy field in the Y direction of the first ferromagnetic layer 1 is 50 Oe or more. The anisotropy field in the Y direction of the first ferromagnetic layer 1 is preferably 70 Oe or more, more preferably 100 Oe or more, even more preferably 200 Oe or more, and particularly preferably 280 Oe or more. The first ferromagnetic layer 1 has a large magnetic anisotropy in one direction in the XY plane. This large magnetic anisotropy is achieved by performing annealing in a magnetic field, which will be described later.

[0039] The thickness of the first ferromagnetic layer 1 is, for example, 2 nm to 20 nm. When the thickness of the first ferromagnetic layer 1 is in this range, the uniaxial magnetic anisotropy of the first ferromagnetic layer 1 is large.

[0040] FIG. 2 is a plan view of the magnetoresistive effect element 10 according to the first embodiment, viewed from the Z direction. The shape of the first ferromagnetic layer 1 in the plan view from the Z direction is, for example, circular or rectangular. The shape of the first ferromagnetic layer 1 in the plan view from the Z direction is, for example, isotropic. The width Wx of the first ferromagnetic layer 1 in the X direction is, for example, 90% to 110% of the width Wy of the first ferromagnetic layer 1 in the Y direction. The width of the first ferromagnetic layer 1 in the major axis direction is, for example, 110% or less of the width of the first ferromagnetic layer 1 in the minor axis direction. When the shape in the plan view is isotropic, shape magnetic anisotropy hardly affects the first ferromagnetic layer 1. By performing annealing in a magnetic field, which will be described later, a large uniaxial magnetic anisotropy can be achieved even in a first ferromagnetic layer 1 whose shape in the plan view from the Z direction is approximately isotropic.

[0041] The shape of the first ferromagnetic layer 1 in a planar view in the Z direction may be anisotropic. For example, the width Wx of the first ferromagnetic layer 1 in the X direction may be, for example, more than 110% of the width Wy of the first ferromagnetic layer 1 in the Y direction. The width of the first ferromagnetic layer 1 in the major axis direction may be, for example, more than 110% of the width of the first ferromagnetic layer 1 in the minor axis direction, and is preferably 150% or more. When the major axis of the first ferromagnetic layer 1 is in the X direction, shape magnetic anisotropy acts on the magnetization of the first ferromagnetic layer 1, further enhancing the uniaxial magnetic anisotropy of the first ferromagnetic layer 1. In this case, the anisotropy field in the Y direction of the first ferromagnetic layer 1 can be 350 Oe or more.

[0042] The uniaxial magnetic anisotropy energy of the first ferromagnetic layer 1 is, for example, 2.0×10 4 erg / cm or more, preferably 5.0 × 10 4 erg / cm or more, and more preferably 1.0 × 10 5 erg / cm or higher.

[0043] The second ferromagnetic layer 2 faces the first ferromagnetic layer 1 with a nonmagnetic layer 3 sandwiched therebetween. Similar to the first ferromagnetic layer 1, the second ferromagnetic layer 2 is an in-plane magnetized film whose magnetization is oriented in one direction within the XY plane.

[0044] The second ferromagnetic layer 2 is, for example, a metal selected from the group consisting of Cr, Mn, Co, Fe, and Ni, an alloy containing one or more metals selected from this group, or an alloy containing one or more metals selected from these and at least one element selected from B, C, and N. The second ferromagnetic layer 2 is, for example, a Co-Fe, Co-Fe-B, Ni-Fe, a Co-Ho alloy (CoHo2), a Sm-Fe alloy (SmFe 12 The second ferromagnetic layer 2 may be a ferromagnetic material having the same composition as the first ferromagnetic layer 1. The second ferromagnetic layer 2 may also be a Heusler alloy.

[0045] The nonmagnetic layer 3 is located between the first ferromagnetic layer 1 and the second ferromagnetic layer 2. The nonmagnetic layer 3 has a thickness of, for example, 1 nm to 10 nm. The nonmagnetic layer 3 inhibits magnetic coupling between the first ferromagnetic layer 1 and the second ferromagnetic layer 2.

[0046] The nonmagnetic layer 3 is made of, for example, a nonmagnetic insulator. Examples of nonmagnetic insulators include Al2O3, SiO2, MgO, MgAl2O4, and materials in which part of the Al, Si, and Mg in these materials are substituted with Zn, Be, or the like. These materials have a wide band gap and excellent insulating properties. The nonmagnetic layer 3 contains, for example, magnesium and oxygen. The nonmagnetic layer 3 is, for example, MgO or MgAl2O4. The nonmagnetic layer 3 containing magnesium and oxygen has excellent lattice matching with the first ferromagnetic layer 1 and the second ferromagnetic layer 2 adjacent to the nonmagnetic layer 3. The lattice matching between the second ferromagnetic layer 2 and the nonmagnetic layer 3 is, for example, within 10%, and preferably within 5%.

[0047] The non-magnetic layer 3 may be a non-magnetic metal or semiconductor. The non-magnetic metal is, for example, a metal or alloy containing any element selected from the group consisting of Cu, Au, Ag, Al, and Cr. Metals or alloys containing these elements have excellent conductivity and reduce the area resistance (hereinafter referred to as RA) of the magnetoresistive element 10. The non-magnetic semiconductor is, for example, Si, Ge, CuInSe2, CuGaSe2, Cu(In,Ga)Se2, etc.

[0048] The underlayer 4 sandwiches the first ferromagnetic layer 1 together with the nonmagnetic layer 3. The first ferromagnetic layer 1 is, for example, stacked on the underlayer 4. The underlayer 4 enhances the crystal orientation of the first ferromagnetic layer 1 and the second ferromagnetic layer 2.

[0049] The underlayer 4 contains Ta. The underlayer 4 may be made of Ta. The underlayer 4 containing Ta absorbs boron or carbon contained in the first ferromagnetic layer 1 by annealing in a magnetic field, which will be described later. When the boron or carbon contained in the first ferromagnetic layer 1 is absorbed, the crystallinity of the first ferromagnetic layer 1 is improved, and the uniaxial magnetic anisotropy of the first ferromagnetic layer 1 is also improved.

[0050] "Method of manufacturing a magnetoresistive element" 3 and 4 are diagrams illustrating a method for manufacturing the magnetoresistive effect element 10 according to the first embodiment. The method for manufacturing the magnetoresistive effect element 10 includes a stacking step, a magnetic field application annealing step, and a processing step.

[0051] 3 is a diagram illustrating the lamination process. In the lamination process, an underlayer 94, a first ferromagnetic layer 91, a non-magnetic layer 93, and a second ferromagnetic layer 92 are laminated in this order. The layers can be laminated by sputtering, chemical vapor deposition (CVD), electron beam evaporation (EB evaporation), atomic laser deposition, or the like.

[0052] The underlayer 94 corresponds to the underlayer 4 and contains Ta. The first ferromagnetic layer 91 corresponds to the first ferromagnetic layer 1 and contains Co. α Fe β X γ Pt δ In the composition formula, α, β, γ, δ, and X are the same as those in the first ferromagnetic layer 1. The nonmagnetic layer 93 corresponds to the nonmagnetic layer 3 and contains, for example, magnesium and oxygen. The second ferromagnetic layer 92 corresponds to the second ferromagnetic layer 2.

[0053] Before the magnetic field application annealing process, the first ferromagnetic layer 91 is an in-plane magnetized film due to the influence of shape magnetic anisotropy, whereas before the magnetic field application annealing process, the magnetization of the first ferromagnetic layer 91 is oriented isotropically in-plane and does not have uniaxial magnetic anisotropy.

[0054] 4 is a diagram for explaining magnetic field application annealing. In the magnetic field application annealing step, annealing is performed while applying a magnetic field H in the X direction.

[0055] In the magnetic field application annealing step, the annealing temperature is preferably 200° C. or higher. If the annealing temperature during application of the magnetic field H is high, the crystals of the first ferromagnetic layer 91 are more likely to move under the influence of the magnetic field H, and the magnetization is more likely to be oriented in one direction.

[0056] In the magnetic field application annealing step, the annealing time is preferably 30 minutes or more, and the magnetic field strength is preferably 1 kOe or more. By applying a magnetic field of sufficient strength, magnetization can be easily oriented in one direction.

[0057] In the magnetic field application annealing step, the easy axis of magnetization of the first ferromagnetic layer 1 is the X direction even before the processing step. The anisotropy magnetic field of the first ferromagnetic layer 1 in the Y direction is 50 Oe or more due to the magnetic field application annealing step.

[0058] Next, a processing step is performed. The processing step can be performed using, for example, photolithography. The laminated film is processed into a predetermined shape to obtain the magnetoresistive element 10. The underlayer 94 becomes the underlayer 4, the first ferromagnetic layer 91 becomes the first ferromagnetic layer 1, the nonmagnetic layer 93 becomes the nonmagnetic layer 3, and the second ferromagnetic layer 92 becomes the second ferromagnetic layer 2. Here, the processing step is performed after the magnetic field application annealing step, but the processing step may be performed before the magnetic field application annealing step.

[0059] The magnetoresistive element 10 according to this embodiment is highly stable because the magnetization of the first ferromagnetic layer 1 is strongly oriented in the X direction. The magnetoresistive element 10 according to this embodiment is unlikely to undergo unexpected magnetization reversal due to external force, even when heat or an external magnetic field is applied.

[0060] The magnetoresistive element 10 according to this embodiment can be used as, for example, a magnetic memory or a magnetic sensor.

[0061] 5 is a circuit schematic diagram of a magnetic memory 110 according to this embodiment. The magnetic memory 110 includes a plurality of magnetoresistive effect elements 11, a plurality of first wirings L1, a plurality of second wirings L2, a plurality of third wirings L3, a plurality of first switches 101, a plurality of second switches 102, and a plurality of third switches 103. In the magnetic memory 110, for example, the magnetoresistive effect elements 11 are arranged in an array.

[0062] Each of the first wirings L1 electrically connects a power supply to one or more magnetoresistive effect elements 11. Each of the second wirings L2 is a wiring used both when writing and reading data. Each of the second wirings L2 electrically connects a reference potential to one or more magnetoresistive effect elements 11. The reference potential is, for example, ground. Each of the third wirings L3 electrically connects a power supply to one or more magnetoresistive effect elements 11. The power supply is connected to the magnetic memory 110 during use.

[0063] Each magnetoresistive effect element 11 is connected to a first switch 101, a second switch 102, and a third switch 103, respectively. The first switch 101 is connected between the magnetoresistive effect element 11 and a first wiring L1. The second switch 102 is connected between the magnetoresistive effect element 11 and a second wiring L2. The third switch 103 is connected between the magnetoresistive effect element 11 and a third wiring L3. Any of the first switch 101, the second switch 102, and the third switch 103 may be shared by the magnetoresistive effect elements 11 connected to the same wiring. Each of the first switch 101, the second switch 102, and the third switch 103 can be a known element such as a transistor.

[0064] 6 is a cross-sectional view of a magnetoresistive effect element 11 used in a magnetic memory 110 according to this embodiment. The magnetoresistive effect element 10 includes a first ferromagnetic layer 1, a second ferromagnetic layer 2, a non-magnetic layer 3, an underlayer 5, a first electrode 6, and a second electrode 7. The magnetoresistive effect element 11 is a magnetoresistive effect element that performs magnetization reversal using spin orbit torque (SOT), and may be called a spin orbit torque type magnetoresistive effect element, a spin injection type magnetoresistive effect element, or a spin current magnetoresistive effect element.

[0065] The first ferromagnetic layer 1, the second ferromagnetic layer 2, and the non-magnetic layer 3 are the same as those described above. The top surface of the second ferromagnetic layer 2 is connected to the third wiring L3. The underlayer 5 is the same as the underlayer 4, except that its length in the X direction is longer than its length in the Y direction. The first electrode 6 is connected to a first end of the underlayer 5. The first electrode 6 is also connected to the first wiring L1. The second electrode 7 is connected to a second end of the underlayer 5. The second electrode 7 is also connected to the second wiring L2. The first electrode 6 and the second electrode 7 are conductors.

[0066] The magnetoresistive element 11 is an element that records and stores data. The magnetoresistive element 11 records data as a resistance value in the z direction. The resistance value in the z direction of the magnetoresistive element 11 changes when a write current is applied along the underlayer 5 and spins are injected from the underlayer 5 into the first ferromagnetic layer 1. The resistance value in the z direction of the magnetoresistive element 11 can be read by applying a read current between the second ferromagnetic layer 2 and the first electrode 6 or the second electrode 7.

[0067] Spins are injected into the first ferromagnetic layer 1 from the underlayer 5. The underlayer 5 induces a spin current by spin-orbit interaction and the interfacial Rashba effect, and injects spins into the first ferromagnetic layer 1. The underlayer 5 applies a spin-orbit torque (SOT) to the magnetization of the first ferromagnetic layer 1 that is sufficient to reverse the magnetization of the first ferromagnetic layer 1, for example.

[0068] The spin Hall effect is a phenomenon in which, when an electric current is passed through it, a spin current is induced in a direction perpendicular to the direction of the electric current due to the spin-orbit interaction. The spin Hall effect is similar to the standard Hall effect in that the direction of movement of moving charges (electrons) is bent. In the standard Hall effect, the direction of movement 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 can be bent simply by moving electrons (current flow) even in the absence of a magnetic field.

[0069] For example, when a current flows along the underlayer 5, the first spins polarized in one direction and the second spins polarized in the opposite direction to the first spins are bent by the spin Hall effect in directions perpendicular to the direction of the current flow. For example, the first spins polarized in the -y direction are bent from the x direction, which is the direction of travel, to the +z direction, and the second spins polarized in the +y direction are bent from the x direction, which is the direction of travel, to the -z direction.

[0070] In non-magnetic materials (materials that are not ferromagnetic), the number of electrons with the first spin, which is generated by the spin Hall effect, is equal to the number of electrons with the second spin. In other words, the number of electrons with the first spin in the +z direction is equal to the number of electrons with the second spin in the -z direction. The first and second spins flow in a direction that eliminates the spin imbalance. When the first and second spins move in the z direction, the flow of charge cancels each other out, so the amount of current is zero. Spin current that does not involve current is specifically called pure spin current.

[0071] The flow of electrons with the first spin is called J ↑ , the flow of electrons of the second spin is J ↓ , the spin current is J S Then, J S =J ↑ -J ↓ is defined as the spin current J S The first spins are injected from the underlayer 5 into the first ferromagnetic layer 1 in the z direction.

[0072] The magnetization of the first ferromagnetic layer 1 is subjected to spin-orbit torque (SOT) by the injected spins, and the orientation direction changes. The underlayer 5 contains Ta. Ta generates strong spin-orbit interaction, allowing a large number of spins to be injected into the first ferromagnetic layer 1.

[0073] The magnetoresistive element 11 has high magnetization stability because the first ferromagnetic layer 1 is oriented in the in-plane X direction. Therefore, the magnetic memory 110 having this magnetoresistive element 11 is highly reliable, with data being less likely to be rewritten by unexpected external forces.

[0074] 7 is a circuit diagram of another example of the magnetic memory according to this embodiment. The magnetic memory 111 shown in FIG. 7 includes a plurality of magnetoresistive elements 10, a plurality of fourth wirings L4, a plurality of fifth wirings L5, and a plurality of fourth switches 104.

[0075] The magnetoresistive effect elements 10 are arranged, for example, in a matrix form, and each of the magnetoresistive effect elements 10 is connected to a fourth wiring L4 and a fifth wiring L5.

[0076] The flow of current to the magnetoresistive element 10 is controlled by a fourth switch 104. Data is written to and read from the magnetoresistive element 10 by turning on the fourth switch 104. Data is written to the magnetoresistive element 10 using spin transfer torque by causing a current to flow in the stacking direction. The fourth switch 104 is similar to the first switch 101 and the like.

[0077] The magnetic memory 111 has a magnetoresistive effect element 10 including a first ferromagnetic layer 1 in which magnetization is strongly oriented in one in-plane direction, and therefore data is less likely to be rewritten by unexpected external forces, resulting in excellent reliability.

[0078] 8 is a schematic diagram of a magnetic sensor 120 according to this embodiment. The magnetic sensor 120 includes a magnetoresistive element 10 and a detector 105.

[0079] The detector 105 detects a change in resistance of the magnetoresistive element 10. A first end of the detector 105 is connected to the underlayer 4, and a second end of the detector 105 is connected to the second ferromagnetic layer 2. When a magnetic field to be detected is applied to the first ferromagnetic layer 1 of the magnetoresistive element 10, the magnetization of the first ferromagnetic layer 1 precesses. When the magnetization of the first ferromagnetic layer 1 precesses, the relative angle between the magnetizations of the first ferromagnetic layer 1 and the second ferromagnetic layer 2 changes, and the resistance value of the magnetoresistive element 10 changes. For example, when the magnetic sensor 120 detects a leakage magnetic field from the magnetization written in a magnetic recording medium, the magnetic sensor 120 functions as a magnetic head.

[0080] The magnetic sensor 120 has a magnetoresistive element 10 including a first ferromagnetic layer 1 whose magnetization is strongly oriented in one in-plane direction, and therefore data is less likely to be rewritten by unexpected external forces, resulting in excellent reliability.

[0081] "Magnetic laminated film" 9 is a cross-sectional view of a magnetic laminated film according to this embodiment. The magnetic laminated film 20 has an underlayer 4 and a first ferromagnetic layer 1. The first ferromagnetic layer 1 is laminated on the underlayer 4. An intermediate layer may be present between the first ferromagnetic layer 1 and the underlayer 4.

[0082] The first ferromagnetic layer 1 and the underlayer 4 are the same as those of the magnetoresistive element 10. The underlayer 4 may contain Ta or may be made of Ta. The first ferromagnetic layer 1 is made of Co α Fe β X γ Pt δ where X is boron or carbon and satisfies α+β+γ+δ=1, α≧β>0, 0.05≦γ≦0.2, and 0.05≦δ≦0.3. The easy axis of magnetization of the first ferromagnetic layer is in the X direction, and the anisotropy magnetic field of the first ferromagnetic layer in the Y direction is 50 Oe or more.

[0083] In the magnetic laminated film according to this embodiment, the first ferromagnetic layer 1 is strongly oriented in one in-plane direction (X direction), and therefore the magnetization is highly stable.

[0084] The magnetic laminated film according to this embodiment can also be used as an anisotropic magnetic sensor, or an optical element that utilizes the magnetic Kerr effect or the magnetic Faraday effect.

[0085] Although several embodiments have been described above as examples of preferred aspects of the present invention, the present invention is not limited to these embodiments. For example, the characteristic features of each embodiment may be applied to other embodiments. [Example]

[0086] "Example 1" In Example 1, a magnetoresistive element having the following configuration was fabricated. Base layer: Ta First ferromagnetic layer: 3 nm thick Co 0.4 Fe 0.4 B 0.2 Non-magnetic layer: MgO Second ferromagnetic layer: Co 0.2 Fe 0.6 B 0.2 Planar shape: Square with 10 mm length in the X and Y directions

[0087] The magnetoresistive element according to Example 1 was fabricated by sequentially stacking an underlayer, a first ferromagnetic layer, a non-magnetic layer, and a second ferromagnetic layer, annealing the layers under a magnetic field, and then processing the layers into a predetermined shape. The annealing was performed under the following conditions: an annealing temperature of 350°C, an annealing time of 60 minutes, and a magnetic field strength of 10 kOe.

[0088] The magnetization of the first ferromagnetic layer of the magnetoresistive element of Example 1 was oriented in the in-plane X-direction in the absence of a magnetic field. The anisotropy field in the Y-direction of the first ferromagnetic layer was 50 Oe. The uniaxial magnetic anisotropy energy of the first ferromagnetic layer was 3.6×10 4 erg / cm.

[0089] "Example 2" In Example 2, the composition of the first ferromagnetic layer was Co 0.5 Fe 0.3 B 0.2Example 2 differs from Example 1 in that α>β. Other conditions were the same as in Example 1, and measurements similar to those in Example 1 were carried out.

[0090] The magnetization of the first ferromagnetic layer of the magnetoresistive element of Example 2 was oriented in the in-plane X-direction in the absence of a magnetic field. The anisotropy field of the first ferromagnetic layer in the Y-direction was 63 Oe. The uniaxial magnetic anisotropy energy of the first ferromagnetic layer was 4.5×10 4 erg / cm.

[0091] "Comparative Example 1" In Comparative Example 1, the composition of the first ferromagnetic layer was Co 0.2 Fe 0.6 B 0.2 Comparative Example 1 differs from Example 1 in that α<β. The other conditions were the same as in Example 1, and measurements similar to those in Example 1 were carried out.

[0092] The magnetization of the first ferromagnetic layer of the magnetoresistive element of Comparative Example 1 was oriented in the in-plane X direction in the absence of a magnetic field. The anisotropy magnetic field of the first ferromagnetic layer in the Y direction was 25 Oe. The uniaxial magnetic anisotropy energy of the first ferromagnetic layer was 1.7×10 4 erg / cm.

[0093] "Example 3" In Example 3, the composition of the first ferromagnetic layer was Co 0.36 Fe 0.36 B 0.13 Pt 0.15 Example 3 differs from Example 1 in that δ=0.15 and the first ferromagnetic layer 1 contains Pt. The other conditions were the same as in Example 1, and measurements similar to those in Example 1 were carried out.

[0094] The magnetization of the first ferromagnetic layer of the magnetoresistive element of Example 3 was oriented in the in-plane X-direction in the absence of a magnetic field. The anisotropy field of the first ferromagnetic layer in the Y-direction was 64 Oe. The uniaxial magnetic anisotropy energy of the first ferromagnetic layer was 3.6×10 4 erg / cm.

[0095] Example 4 In Example 4, the composition of the first ferromagnetic layer was Co 0.33 Fe 0.33 B 0.13 Pt 0.21 Example 4 differs from Example 3 in that δ=0.21. Other conditions were the same as in Example 3, and measurements similar to those in Example 3 were carried out.

[0096] The magnetization of the first ferromagnetic layer of the magnetoresistive element of Example 4 was oriented in the in-plane X-direction in the absence of a magnetic field. The anisotropy field in the Y-direction of the first ferromagnetic layer was 127 Oe. The uniaxial magnetic anisotropy energy of the first ferromagnetic layer was 6.9×10 4 erg / cm.

[0097] "Example 5" In Example 5, the composition of the first ferromagnetic layer was Co 0.31 Fe 0.31 B 0.12 Pt 0.26 Example 5 differs from Example 3 in that δ=0.26. Other conditions were the same as in Example 3, and measurements similar to those in Example 3 were carried out.

[0098] The magnetization of the first ferromagnetic layer of the magnetoresistive element of Example 5 was oriented in the in-plane X-direction in the absence of a magnetic field. The anisotropy field of the first ferromagnetic layer in the Y-direction was 145 Oe. The uniaxial magnetic anisotropy energy of the first ferromagnetic layer was 6.3×10 4 erg / cm.

[0099] "Example 6" In Example 6, the composition of the first ferromagnetic layer was Co 0.46 Fe 0.27 B 0.14 Pt 0.13 Example 6 differs from Example 2 in that δ=0.13 and the first ferromagnetic layer 1 contains Pt. The other conditions were the same as in Example 2, and measurements similar to those in Example 2 were carried out.

[0100] The magnetization of the first ferromagnetic layer of the magnetoresistive element of Example 6 was oriented in the in-plane X-direction in the absence of a magnetic field. The anisotropy field of the first ferromagnetic layer in the Y-direction was 100 Oe. The uniaxial magnetic anisotropy energy of the first ferromagnetic layer was 5.7×10 4 erg / cm.

[0101] "Example 7" In Example 7, the composition of the first ferromagnetic layer was Co 0.41 Fe 0.26 X 0.13 Pt 0.20 Example 7 differs from Example 6 in that δ=0.20. Other conditions were the same as in Example 6, and measurements similar to those in Example 6 were carried out.

[0102] The magnetization of the first ferromagnetic layer of the magnetoresistive element of Example 7 was oriented in the in-plane X direction in the absence of a magnetic field. The anisotropy field of the first ferromagnetic layer in the Y direction was 125 Oe. The uniaxial magnetic anisotropy energy of the first ferromagnetic layer was 6.6×10 4 erg / cm.

[0103] "Example 8" In Example 8, the composition of the first ferromagnetic layer was Co 0.38 Fe 0.24 X 0.12 Pt 0.26 Example 8 differs from Example 6 in that δ=0.26. Other conditions were the same as in Example 6, and measurements similar to those in Example 6 were carried out.

[0104] The magnetization of the first ferromagnetic layer of the magnetoresistive element of Example 8 was oriented in the in-plane X direction in the absence of a magnetic field. The anisotropy field of the first ferromagnetic layer in the Y direction was 187 Oe. The uniaxial magnetic anisotropy energy of the first ferromagnetic layer was 7.7×10 4 erg / cm.

[0105] "Example 9" Example 9 differs from Example 7 in that the thickness of the first ferromagnetic layer was set to 2 nm. The other conditions were the same as in Example 7, and measurements similar to those in Example 7 were carried out.

[0106] The magnetization of the first ferromagnetic layer of the magnetoresistive element of Example 9 was oriented in the in-plane X direction in the absence of a magnetic field. The anisotropy field in the Y direction of the first ferromagnetic layer was 89 Oe. The uniaxial magnetic anisotropy energy of the first ferromagnetic layer was 3.8×10 4 erg / cm.

[0107] "Example 10" Example 10 differs from Example 7 in that the thickness of the first ferromagnetic layer was set to 8 nm. The other conditions were the same as in Example 7, and measurements similar to those in Example 7 were carried out.

[0108] The magnetization of the first ferromagnetic layer of the magnetoresistive element of Example 10 was oriented in the in-plane X direction in the absence of a magnetic field. The anisotropy field of the first ferromagnetic layer in the Y direction was 233 Oe. The uniaxial magnetic anisotropy energy of the first ferromagnetic layer was 1.4×10 5 erg / cm.

[0109] "Example 11" Example 11 differs from Example 7 in that the thickness of the first ferromagnetic layer was set to 20 nm. The other conditions were the same as in Example 7, and measurements similar to those in Example 7 were carried out.

[0110] The magnetization of the first ferromagnetic layer of the magnetoresistive element of Example 11 was oriented in the in-plane X direction in the absence of a magnetic field. The anisotropy field of the first ferromagnetic layer in the Y direction was 145 Oe. The uniaxial magnetic anisotropy energy of the first ferromagnetic layer was 8.2×10 4 erg / cm.

[0111] "Example 12" Example 12 differs from Example 11 in that the annealing temperature was set to 300° C. The other conditions were the same as in Example 11, and measurements similar to those in Example 11 were carried out.

[0112] The magnetization of the first ferromagnetic layer of the magnetoresistive element of Example 12 was oriented in the in-plane X direction in the absence of a magnetic field. The anisotropy field of the first ferromagnetic layer in the Y direction was 271 Oe. The uniaxial magnetic anisotropy energy of the first ferromagnetic layer was 1.5×10 5 erg / cm.

[0113] "Example 13" Example 13 differs from Example 11 in that the annealing temperature was set to 250° C. The other conditions were the same as in Example 11, and measurements similar to those in Example 11 were carried out.

[0114] The magnetization of the first ferromagnetic layer of the magnetoresistive element of Example 13 was oriented in the in-plane X direction in the absence of a magnetic field. The anisotropy field in the Y direction of the first ferromagnetic layer was 173 Oe. The uniaxial magnetic anisotropy energy of the first ferromagnetic layer was 9.9×10 4 erg / cm.

[0115] The above results are summarized in the table below.

[0116] [Table 1]

[0117] As shown in Table 1 above, Examples 1 to 12 have larger uniaxial anisotropy than Comparative Example 1. Therefore, the magnetoresistive effect elements of Examples 1 to 12 have excellent magnetization stability. [Explanation of symbols]

[0118] 1, 91 first ferromagnetic layer 2, 92 second ferromagnetic layer 3, 93 nonmagnetic layer 4, 5, 94 Base layer 6 1st electrode 7 Second electrode 10, 11 Magnetoresistive element 20 Magnetic laminated film 101 First Switch 102 Second Switch 103 Third Switch 104 4th Switch 105 detector 110, 111 Magnetic memory 120 Magnetic Sensor L1 First wiring L2 Second wiring L3 Third wiring L4 4th wiring L5 5th wiring Wx, Wy width

Claims

1. a lamination step of laminating an underlayer, a first ferromagnetic layer, a non-magnetic layer, and a second ferromagnetic layer in this order; a magnetic field application annealing step of annealing while applying a magnetic field in a first direction in a plane perpendicular to the stacking direction, the underlayer contains Ta, The first ferromagnetic layer is made of Co α Fe β X γ Pt δ is expressed as X is boron or carbon; A method for manufacturing a magnetoresistive element that satisfies α+β+γ+δ=1, α≧β>0, and δ≦0.

3.

2. 2. The method for manufacturing a magnetoresistive element according to claim 1, wherein the annealing temperature in the magnetic field application annealing step is 200[deg.] C. or higher.

3. 2. The method for manufacturing a magnetoresistive element according to claim 1, wherein the annealing time in the magnetic field application annealing step is 30 minutes or more.

4. 2. The method for manufacturing a magnetoresistive element according to claim 1, wherein the strength of the magnetic field applied in the magnetic field application annealing step is 1 kOe or more.

5. 2. The method for manufacturing a magnetoresistive element according to claim 1, wherein γ satisfies 0.05≦γ≦0.

2.

6. 2. The method for manufacturing a magnetoresistive element according to claim 1, wherein δ satisfies 0.05≦δ≦0.

3.

7. The method for manufacturing a magnetoresistive element according to claim 1 , wherein the non-magnetic layer contains magnesium and oxygen.

8. a first ferromagnetic layer, a second ferromagnetic layer, a non-magnetic layer, and an underlayer; the nonmagnetic layer is located between the first ferromagnetic layer and the second ferromagnetic layer, the first ferromagnetic layer is located between the underlayer and the nonmagnetic layer, the underlayer contains Ta, The first ferromagnetic layer is made of Co α Fe β X γ Pt δ is expressed as X is boron or carbon; The following conditions are satisfied: α+β+γ+δ=1, α≧β>0, and δ≦0.3; the first ferromagnetic layer has an easy axis of magnetization in a first direction in a plane perpendicular to the stacking direction; the anisotropy magnetic field of the first ferromagnetic layer in the second direction is 50 Oe or more; The second direction is perpendicular to the stacking direction and the first direction.

9. 9. The magnetoresistive element according to claim 8, wherein γ satisfies 0.05≦γ≦0.

2.

10. 9. The magnetoresistive element according to claim 8, wherein δ satisfies 0.05≦δ≦0.

3.

11. 9. The magnetoresistive element according to claim 8, wherein the nonmagnetic layer contains magnesium and oxygen.

12. 9. The magnetoresistive element according to claim 8, wherein the first ferromagnetic layer has a thickness of 2 nm or more and 20 nm or less.

13. The first ferromagnetic layer has a uniaxial magnetic anisotropy energy of 2.0×10 ４ 9. The magnetoresistive element according to claim 8, wherein the resistivity is erg / cm or more.

14. Further comprising a first electrode and a second electrode; the first electrode is connected to a first end of the underlayer; The magnetoresistive element according to claim 8 , wherein the second electrode is connected to a second end of the underlayer that is different from the first end.

15. 9. The magnetoresistive effect element according to claim 8, wherein, in a planar view from the stacking direction, the width of the first ferromagnetic layer in the first direction is 90% or more and 110% or less of the width of the first ferromagnetic layer in the second direction.

16. an underlayer and a first ferromagnetic layer; the underlayer is in contact with one surface of the first ferromagnetic layer, the underlayer contains Ta, The first ferromagnetic layer is made of Co α Fe β X γ Pt δ is expressed as X is boron or carbon; The following conditions are satisfied: α+β+γ+δ=1, α≧β>0, 0.05≦γ≦0.2, and 0.05≦δ≦0.3; the first ferromagnetic layer has an easy axis of magnetization in a first direction in a plane perpendicular to the stacking direction; the anisotropy magnetic field of the first ferromagnetic layer in the second direction is 50 Oe or more; The magnetic laminated film, wherein the second direction is perpendicular to the lamination direction and the first direction.

17. A magnetic memory comprising the magnetoresistive element according to claim 8 .

18. A magnetic sensor comprising the magnetoresistive element according to claim 8 .

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