Magnetic laminated film, magnetic memory element, magnetic memory and artificial intelligence system

Abstract

Provided are a magnetic laminated film capable of reducing the roughness of a heavy metal layer and reducing power consumption, and a magnetic memory element, a magnetic memory, and an artificial intelligence system using the magnetic laminated film. A magnetic laminated film 1 is for a magnetic memory element, and is provided with: an amorphous heavy metal layer 2 having a structure where first layers containing Hf and second layers containing a heavy metal excluding Hf are alternately laminated; and a recording layer 10 that includes a ferromagnetic layer having a reversible magnetizing direction and that is adjacent to the heavy metal layer 2.

Description

[Technical field]

[0001] The present invention relates to a magnetic laminated film, a magnetic memory element, a magnetic memory, and an artificial intelligence system. [Background technology]

[0002] As a next-generation non-volatile magnetic memory that can achieve high speed and high rewrite resistance, MRAM (Magnetic Random Access Memory) using a magnetoresistance effect element (Magnetic Tunnel Junction: MTJ) as a memory element is known. As next-generation magnetic memory elements to be used in MRAM, STT-MRAM (Spin Transfer Torque Random Access Memory) elements that use spin transfer torque to reverse the magnetization of a magnetic tunnel junction and SOT-MRAM (Spin-Orbit Torque Magnetic Random Access Memory) elements that use spin orbit torque to reverse the magnetization of an MTJ (see Patent Document 1) are attracting attention.

[0003] Of the above, the SOT-MRAM element has a structure in which an MTJ including a three-layer structure of a ferromagnetic layer / insulating layer / ferromagnetic layer is provided on a heavy metal layer. In the case of currently used Co-Fe type magnetic materials, SOT-MRAM elements have the property that the resistance of the element is higher when the magnetization directions of the recording layer and reference layer are in an antiparallel state, where the magnetization directions are antiparallel, than when they are in a parallel state, where the magnetization directions of the recording layer and reference layer are parallel, and data is recorded by corresponding the parallel state and antiparallel state to 0 and 1. In SOT-MRAM elements, a spin current is induced by spin-orbit interaction by passing a current through the heavy metal layer, and the spins polarized by the spin current flow into the recording layer, causing the magnetization of the recording layer to be reversed. This allows the SOT-MRAM element to switch between the parallel state and the antiparallel state and record data.

[0004] Also, for SOT-MRAM elements, an architecture has been proposed in which a large number of MTJs are arranged on a heavy metal layer in order to achieve high integration (see Patent Document 1). In the architecture of Patent Document 1, data is written to the MTJ by utilizing a mechanism in which the magnetic anisotropy of the MTJ can be controlled by applying a voltage to the MTJ. First, a voltage is applied to the MTJ to which data is to be written, lowering the magnetic anisotropy of the recording layer and putting the recording layer in a state in which magnetization reversal is easy to occur (also called a semi-selected state). Then, a write current is passed through the heavy metal layer to reverse the magnetization of the recording layer and write data. In this way, in the magnetic memory of Patent Document 1, the MTJ to which data is to be written can be selected by applying a voltage to the MTJ.

[0005] Furthermore, an electronic neuron using SOT-MRAM elements has been proposed (see Patent Document 2). In this configuration, the magnetization direction of the neuron is determined by the total synaptic current. A resistive crossbar array is used that functions as a synapse to generate a bipolar current that is a weighted sum of input signals. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2017-112351 A [Patent Document 2] US Patent Application Publication No. 2017 / 0330070 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when β-W is used as a heavy metal layer in SOT-MRAM elements, problems arise in that the high electrical resistivity of β-W results in high power consumption, and the large roughness on β-W results in large variations in MTJ characteristics. Therefore, there is a demand for reducing power consumption and reducing the roughness of the heavy metal layer.

[0008] Therefore, the present invention has been made in consideration of the above-mentioned problems, and aims to provide a magnetic laminated film that can reduce power consumption and the roughness of a heavy metal layer, and a magnetic memory element, a magnetic memory, and an artificial intelligence system that use the magnetic laminated film. [Means for solving the problem]

[0009] The magnetic laminated film according to the present invention is a laminated film for a magnetic memory element, and comprises an amorphous heavy metal layer having a structure in which a first layer containing Hf and a second layer containing a heavy metal other than Hf are alternately laminated, and a recording layer including a ferromagnetic layer whose magnetization direction is reversible and adjacent to the heavy metal layer.

[0010] The magnetic memory element according to the present invention comprises the above-mentioned magnetic laminated film, a barrier layer made of an insulator adjacent to the recording layer, and a reference layer adjacent to the barrier layer and having a fixed magnetization direction, and the magnetization direction of the ferromagnetic layer of the recording layer is reversed by a write current flowing through the heavy metal layer.

[0011] The magnetic memory according to the present invention comprises the above-mentioned magnetic memory element, a write unit having a write power supply that writes data into the magnetic memory element by passing the write current through the heavy metal layer, and a read unit having a read power supply that passes a read current that passes through the barrier layer, and a current detector that detects the read current that has passed through the barrier layer and reads the data written in the magnetic memory element.

[0012] In the artificial intelligence system according to the present invention, the above-mentioned magnetic memory element is used in an electronic neuron to which the weighted sum of a resistive crossbar network is input. Effect of the Invention

[0013] According to the present invention, the heavy metal layer is an amorphous layer having a structure in which a first layer containing Hf and a second layer containing a heavy metal other than Hf are alternately laminated, thereby making it possible to suppress power consumption and reduce roughness of the heavy metal layer. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view showing a magnetic memory element according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing a cross section of the magnetic memory element of FIG. 1 taken along a plane perpendicular to the y direction. [Diagram 3] FIG. 3 is a schematic cross-sectional view illustrating a method for writing data "0" to a magnetic memory element storing data "1", and shows an initial state. [Figure 4] FIG. 4 is a schematic cross-sectional view for explaining a method for writing data "0" to a magnetic memory element storing data "1", and shows a state in which data has been written by passing a write current. [Diagram 5] FIG. 5 is a schematic cross-sectional view illustrating a method for writing data "1" to a magnetic memory element storing data "0", and shows the initial state. [Figure 6] FIG. 6 is a schematic cross-sectional view for explaining a method for writing data "1" to a magnetic memory element storing data "0", and shows a state in which data has been written by passing a write current. [Figure 7] 10A to 10C are schematic cross-sectional views illustrating a method for reading data stored in a magnetic memory element. [Figure 8] FIG. 8 is a schematic perspective view showing the configuration of a sample for a verification experiment. [Figure 9] FIG. 9 is a schematic cross-sectional view of a sample of a comparative example. [Figure 10] FIG. 10 is a schematic cross-sectional view of the samples of Examples 1 and 2. [Figure 11] FIG. 11 is a schematic cross-sectional view of the sample of Example 3. [Figure 12] FIG. 12 is a TEM image of a cross section of the comparative sample. [Figure 13] FIG. 13 is a TEM image of a cross section of the magnetic laminated film of Example 1. [Figure 14] FIG. 14 is a TEM image of a cross section of the magnetic laminated film of Example 3. [Figure 15] FIG. 15 is a graph showing the dependence of conductance on the thickness of the heavy metal layer in verification experiment 2. [Figure 16] FIG. 16 is a graph showing the electrical resistivity in verification experiment 2. [Figure 17] FIG. 17 is a graph showing the magnetic field dependence of the electrical resistance in Verification Experiment 3 of the sample of Example 2. [Figure 18] FIG. 18 is a graph showing the magnetic field dependence of the electrical resistance in Verification Experiment 3 for the sample of Example 3. [Figure 19] FIG. 19 is a graph showing the film thickness dependence of the spin Hall magnetoresistance ratio in verification experiment 3. In FIG. [Figure 20] FIG. 20 is a graph showing the spin generation efficiency in verification experiment 4. [Figure 21] FIG. 21 is a graph showing the spin diffusion length in verification experiment 5. [Figure 22] FIG. 22 is a graph showing the film thickness dependency of the product of the magnetic anisotropy constant and the effective film thickness of the recording layer (ferromagnetic layer) in Verification Experiment 6. In FIG. [Figure 23A] FIG. 23A is a plan view showing a pillar-shaped MTJ as an example of the magnetic memory element according to the second embodiment of the present invention. [Figure 23B] FIG. 23B is a plan view showing a pillar-shaped MTJ as another example of the magnetic memory element according to the second embodiment of the present invention. [Figure 23C] FIG. 23C is a perspective view showing the magnetic memory element of FIG. 23A. [Figure 24] FIG. 24 is a schematic perspective view showing an example of a magnetic memory using an array of the magnetic memory elements of FIG. 23A. [Figure 25A] FIG. 25A is a plan view showing a pillar-shaped MTJ as another example of the magnetic memory element according to the second embodiment of the present invention. [Figure 25B] FIG. 25B is a plan view showing a pillar-shaped MTJ as another example of the magnetic memory element according to the second embodiment of the present invention. [Figure 26A] FIG. 26A is a plan view showing a pillar-shaped MTJ as another example of the magnetic memory element according to the second embodiment of the present invention. [Figure 26B]FIG. 26B is a plan view showing a pillar-shaped MTJ as another example of the magnetic memory element according to the second embodiment of the present invention. [Figure 27A] FIG. 27A is a plan view showing a pillar-shaped MTJ as an example of the magnetic memory element according to the third embodiment of the present invention. [Figure 27B] FIG. 27B is a perspective view showing a method of writing data to the magnetic memory element of FIG. 27A. [Figure 28] FIG. 28 is a timing chart of signals for writing data to the magnetic memory element of FIG. 27A. [Figure 29] FIG. 29 is a schematic perspective view showing an example of an AI system using the magnetic memory element according to the third embodiment of the present invention. [Diagram 30] FIG. 30 is a circuit diagram of an example of an AI system using a magnetic memory element. [Diagram 31] FIG. 31 is a schematic perspective view showing another example of an AI system using a magnetic memory element. [Diagram 32] FIG. 32 is a plan view of another example of an AI system using a magnetic memory element. [Diagram 33] FIG. 33 is a plan view of another example of an AI system using a magnetic memory element. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] (1) First embodiment (1-1) Overall Configuration of the Magnetic Laminated Film of the First Embodiment Hereinafter, a magnetic laminated film 1 according to an embodiment of the present invention will be described with reference to FIG. 1 and FIG. 2. FIG. 1 is a perspective view showing a magnetic memory element 100 produced using the magnetic laminated film 1. The magnetic memory element 100 is a perpendicular magnetization type SOT-MRAM element in which the magnetization directions of the recording layer 10 and the reference layer 12, each made of a ferromagnetic layer, are perpendicular to the film surface. In this specification, as shown in FIG. 1, the longitudinal direction (direction in which a write current, which will be described later, flows) of the heavy metal layer 2 is the x direction (the upper right direction of the paper is the +x direction), the lateral direction is the y direction (the upper left direction of the paper in the perspective view is the +y direction), and the direction perpendicular to the surface of the heavy metal layer 2 is the z direction (the upper direction of the paper is the +z direction). FIG. 2 is a schematic diagram showing a cross section of the magnetic memory element 100 on a plane perpendicular to the y direction. In this specification, the +z direction is also referred to as, for example, the upper side and the upper portion, and the -z direction is also referred to as, for example, the lower side and the lower portion.

[0016] As shown in FIG. 1, the magnetic laminated film 1 includes an amorphous heavy metal layer 2 having a structure in which a first layer containing Hf and a second layer containing a heavy metal other than Hf are alternately laminated, and a recording layer 10 provided adjacent to the heavy metal layer 2. In this embodiment, the heavy metal layer 2 has a rectangular parallelepiped shape stretched in a first direction (x direction) and has a rectangular shape when viewed from above. The film thickness (length in the z direction) of the heavy metal layer 2 is 1.4 nm to 9 nm, preferably 1.8 nm to 7 nm. Since the diffusion length of electron spin is about 0.6 to 1.5 nm, it is desirable that the film thickness is 1.8 nm (three times the lower limit of the electron spin diffusion length, 0.6 nm) to 4.5 nm (three times the upper limit of the electron spin diffusion length, 1.5 nm). Moreover, since a film thickness six times the spin diffusion length is too thick to not contribute to spin inversion, the film thickness is 9 nm or less (six times the upper limit of the electron spin diffusion length, 1.5 nm), more preferably 7 nm or less, which is four to five times the spin diffusion length.

[0017] The heavy metal layer 2 is desirably rectangular with a length (length in the x direction) of about 10 nm to 260 nm and a width (length in the y direction) of about 5 nm to 150 nm. In this embodiment, the heavy metal layer 2 is designed so that its width in the y direction is larger than the width of the recording layer 10, but when fabricated by a self-alignment process, it is possible and more preferable to make them almost the same.

[0018] In addition, the length of the heavy metal layer 2 is preferably as short as possible as long as a current can flow therethrough. In this way, when a magnetic memory is manufactured using the magnetic memory element 100, the magnetic memory can be made dense. The width of the heavy metal layer 2 is preferably the same as the width of the MTJ, and in this way, the writing efficiency of the magnetic memory element 100 using the magnetic laminated film 1 is maximized. The shape of the heavy metal layer 2 is preferably as described above, but is not particularly limited. The length of the heavy metal layer 2 is a desirable length when the heavy metal layer 2 includes one recording layer 10, and is not limited to the case where one heavy metal layer 2 includes multiple recording layers 10 and multiple MTJs are arranged in the first direction, i.e., multiple magnetic memory elements 100 share one heavy metal layer 2.

[0019] The heavy metal layer 2 is formed of an amorphous layer having a structure in which a first layer containing Hf and a second layer containing a heavy metal other than Hf are alternately laminated, and is conductive. The second layer contains, for example, W or a W alloy, or one or more elements selected from Co, Fe and B. In addition, for example, the layer of the heavy metal layer 2 closest to the recording layer 10 is the first layer. The first layer (hereinafter also referred to as the Hf layer) is a thin film made of hafnium (Hf). By forming the heavy metal layer 2 with the above composition, the heavy metal layer has a spin generation efficiency (θ) equivalent to that of β-phase W (β-W). SH) can be ensured, and high spin reversal efficiency can be realized. Since the spin generation efficiency is inversely proportional to the write current density, when the spin generation efficiency increases, the write current density can be reduced, and the write efficiency of the magnetic memory element 100 using the magnetic laminated film 1 can be improved. The electric resistivity of the amorphous layer having a structure in which the first layer containing Hf and the second layer containing heavy metals other than Hf are alternately laminated is 160 to 200 μΩcm, which is lower than the electric resistivity of conventional β-W (approximately 210 μΩcm). Therefore, the voltage drop due to the read current in the heavy metal layer 2 can be reduced, and the delay in reading the magnetic memory element 100 can be suppressed, and power consumption can be reduced.

[0020] In this embodiment, such a heavy metal layer 2 is, for example, Si, SiO 2 Alternatively, it is provided on a substrate 5 made of SiN or the like. One surface of the substrate 5 is provided with a buffer layer 4 made of, for example, Ta and having a thickness of about 0.5 nm to 7.0 nm. The heavy metal layer 2 is provided adjacent to this buffer layer 4. The substrate 5 may be a circuit board such as a board on which FET type transistors, metal wiring, etc. are formed. In this case, a through hole is provided in the buffer layer 4 to contact the heavy metal layer 2 with the wiring, etc. formed on the substrate 5.

[0021] The recording layer 10 is formed adjacent to the surface of the heavy metal layer 2 opposite to the surface adjacent to the buffer layer 4. The recording layer 10 is formed of a ferromagnetic layer whose magnetization direction is reversible. The thickness of the recording layer 10 is 0.8 nm to 5.0 nm, preferably 1.0 nm to 3.0 nm. In this embodiment, the recording layer 10 is formed in a cylindrical shape, but the shape of the recording layer 10 is not limited.

[0022] The recording layer 10 is a ferromagnetic film formed of a ferromagnetic material. When the magnetic memory element 100 is manufactured, the material and thickness of the recording layer 10 are selected in consideration of the material and thickness of the barrier layer 11 so that interface magnetic anisotropy occurs at the interface between the recording layer 10 and the barrier layer 11 described later. Therefore, the recording layer 10 is magnetized in a direction perpendicular to the film surface (hereinafter simply referred to as the perpendicular direction) due to the interface magnetic anisotropy occurring at the interface between the recording layer 10 and the barrier layer 11. In FIG. 1 and FIG. 2, the magnetization of the recording layer 10 is represented by a white arrow as M10, and the direction of the arrow represents the magnetization direction. The two arrows, one pointing up and one pointing down, drawn on the recording layer 10 indicate that the magnetization of the recording layer 10 can be reversed in a direction perpendicular to the film surface. In reality, the recording layer 10 also includes components that are not oriented in the magnetization direction (the direction of the arrow). Hereinafter, when magnetization is represented by an arrow in the drawings of this specification, this is the same as the above.

[0023] In this way, in order to generate interface magnetic anisotropy in the recording layer 10, it is desirable that the recording layer 10 is formed of CoFeB, FeB, or CoB. The recording layer 10 can also be a multilayer film, in which case a CoFeB layer, FeB layer, or CoB layer is disposed at the interface with a barrier layer 11 such as MgO described later, and a multilayer film containing a Co layer, such as a Co / Pt multilayer film, a Co / Pd multilayer film, and a Co / Ni multilayer film, an ordered alloy such as Mn-Ga, Mn-Ge, and Fe-Pt, or an alloy containing Co, such as Co-Pt, Co-Pd, Co-Cr-Pt, Co-Cr-Ta-Pt, CoFeB, FeB, or CoB, is inserted between the heavy metal layer 2 and the CoFeB layer, FeB layer, or CoB layer. The number of layers and the thickness of these multilayer films and alloys are appropriately adjusted according to the size of the MTJ. The recording layer 10 may be a multi-layer film in which ferromagnetic layers and non-magnetic layers are alternately stacked, for example, a three-layer structure of ferromagnetic layer / non-magnetic layer / ferromagnetic layer, in which the magnetizations of the two ferromagnetic layers are coupled by interlayer interaction. In this case, the non-magnetic layer is made of a non-magnetic material such as Ta, W, Mo, Pt, Pd, Ru, Rh, Ir, Cr, Au, Cu, Os, or Re.

[0024] Although the recording layer 10 is magnetized in the perpendicular direction by the interface magnetic anisotropy, the recording layer 10 may be magnetized in the perpendicular direction by generating an easy axis of magnetization in the perpendicular direction by the crystal magnetic anisotropy or the shape magnetic anisotropy. In this case, the recording layer 10 is preferably an alloy containing at least one of Co, Fe, Ni, and Mn, for example. Specifically, the alloy containing Co is preferably an alloy such as Co-Pt, Co-Pd, Co-Cr-Pt, and Co-Cr-Ta-Pt, and in particular, it is preferable that these alloys are so-called Co-rich alloys containing more Co than other elements. The alloy containing Fe is preferably an alloy such as Fe-Pt and Fe-Pd, and in particular, it is preferable that these alloys are so-called Fe-rich alloys containing more Fe than other elements. The alloy containing Co and Fe is preferably an alloy such as Co-Fe, Co-Fe-Pt, and Co-Fe-Pd. The alloy containing Co and Fe may be Co-rich or Fe-rich. As the alloy containing Mn, alloys such as Mn-Ga and Mn-Ge are preferable. In addition, the alloy containing at least one of Co, Fe, Ni, and Mn described above may contain small amounts of elements such as B, C, N, O, P, Al, and Si.

[0025] When MgO is laminated on an amorphous metal layer, an MgO layer in which single crystals oriented in the (100) direction are predominant is formed, which makes it easier to form an MgO(100) barrier layer 11 adjacent to the recording layer 10, and the recording layer 10 may be an amorphous layer. In this way, the barrier layer 11 made of MgO(100) can be grown on the ferromagnetic material as a (100) highly oriented film with large grains in the in-plane direction, improving the in-plane uniformity of the orientation of MgO(100), and making it possible to improve the uniformity of the resistance change rate (MR change rate).

[0026] The Hf layer constituting the heavy metal layer 2 may contain zirconium (Zr). The recording layer 10 is formed adjacent to the Hf layer, so that the saturation magnetization Ms of the ferromagnetic layer 18 can be suppressed from increasing due to the heat treatment described later, and as a result, the increase in the write current density can also be suppressed, so that the write efficiency of the recording layer 10 can be improved. In addition, since the recording layer 10 is formed adjacent to the Hf layer, the magnetization of the recording layer 10 is reduced, so that the magnitude of the demagnetizing field is reduced, the perpendicular magnetic anisotropy is increased, and magnetization in the perpendicular direction becomes easier. In addition, an increase in the surface magnetic anisotropy constant was also observed at the heavy metal layer 2 / CoFeB interface of this embodiment, as described later. Therefore, the recording layer 10 can be magnetized perpendicularly up to a thicker thickness, so that the thermal stability of the recording layer 10 can be improved. The Hf layer is preferably formed to a thickness of 0.2 nm or more and 0.7 nm or less, more preferably 0.3 nm or more and 0.7 nm or less. To form the Hf layer in a layered form, a thickness of about 0.2 nm is required, and even if the thickness of the Hf layer is made thicker than 0.7 nm, the rate of increase in the spin generation efficiency saturates, and the writing efficiency does not improve much. The heavy metal layer 2 has a structure in which, for example, a 0.35 nm thick Hf layer and a 0.35 nm thick second layer are alternately laminated 2 to 10 times. The thickness of the heavy metal layer 2 when alternately laminated 2 times is 1.4 nm. The thickness of the heavy metal layer 2 when alternately laminated 10 times is 7.0 nm. Alternatively, the heavy metal layer 2 has a structure in which, for example, a 0.7 nm thick Hf layer and a 0.7 nm thick second layer are alternately laminated 1 to 7 times. The thickness of the heavy metal layer 2 when alternately laminated 1 time is 1.4 nm. The thickness of the heavy metal layer 2 when alternately laminated 5 times is 7.0 nm. The thickness of the heavy metal layer other than Hf is within the range of thickness in which the crystal structure remains amorphous, and is preferably 3 nm or less, more preferably 1 nm or less. For example, in the case of W, it was confirmed that the amorphous structure was maintained even in (Hf0.3nm / W3nm)n.

[0027] Such an Hf layer is highly effective when the recording layer 10 is made of a ferromagnetic material containing B (boron), for example, when it is made of CoFeB, FeB, or CoB, or when it is made of a ferromagnetic material containing an alloy of these. When the recording layer 10 has a multi-layer structure, it is preferable that the ferromagnetic layer adjacent to the Hf layer among the layers constituting the recording layer 10 is made of CoFeB, FeB, or CoB.

[0028] In this embodiment, the magnetic laminated film 1 is formed by depositing a buffer layer 4, a heavy metal layer 2, and a recording layer 10 in this order on a substrate 5 by a general film deposition method such as PVD (Physical Vapor Deposition). The heavy metal layer 2 is formed by alternately laminating a Hf layer and a second layer (e.g., a W layer) of a predetermined thickness. The laminated film of the Hf layer / second layer becomes an amorphous film by heat treatment during the manufacture of the magnetic memory element 100 described later. The thickness of the tungsten film and the tantalum film, the composition of the target, the deposition rate, and the like can be appropriately adjusted. Note that, although the term "film" is used for convenience in the above description, the film does not necessarily have to be formed on the entire surface. The recording layer 10 is formed by a known lithography technique.

[0029] (1-2) Magnetic memory element using the magnetic laminated film of the first embodiment 1 and 2, a magnetic memory element 100 using the magnetic laminated film 1 of the first embodiment will be described. The magnetic memory element 100 is a SOT-MRAM element type magnetic memory element including an MTJ having the recording layer 10, barrier layer 11, and reference layer 12 of the magnetic laminated film 1 adjacent to a heavy metal layer 2. In this embodiment, the MTJ is cylindrical in shape to match the shape of the recording layer 10, but the shape of the MTJ is not limited.

[0030] The heavy metal layer 2 and the recording layer 10 of the magnetic memory element 100 have been described above, so a description thereof will be omitted. The barrier layer 11 is formed adjacent to the recording layer 10. The barrier layer 11 is made of MgO, Al 2 O 3It is preferable that the barrier layer 11 is made of an insulator such as AlN or MgAlO, particularly MgO. The thickness of the barrier layer 11 is 0.1 nm to 2.5 nm, preferably 0.5 nm to 1.5 nm.

[0031] Although the reference layer 12 is shown as a single layer structure in the drawing, it is not limited thereto, and may have a three-layer laminated ferrimagnetic structure consisting of a three-layer laminated film in which a ferromagnetic layer, a nonmagnetic layer, and a ferromagnetic layer are laminated in this order. In this case, the magnetization direction of one ferromagnetic layer and the magnetization direction of the other ferromagnetic layer are antiparallel. The magnetization of one ferromagnetic layer is oriented in the -z direction, and the magnetization of the other ferromagnetic layer is oriented in the +z direction. In this specification, when the magnetization directions are said to be antiparallel, it means that the magnetization directions are approximately 180 degrees different, and when the magnetization is oriented in the +z direction, it is said to be upward, and when the magnetization is oriented in the -z direction, it is said to be downward.

[0032] In this embodiment, the material and thickness of the ferromagnetic layer of the reference layer 12 closest to the barrier layer 11 are selected so that interface magnetic anisotropy occurs at the interface between the ferromagnetic layer of the reference layer 12 closest to the barrier layer 11 and the barrier layer 11. This makes the magnetization direction of the ferromagnetic layer of the reference layer 12 closest to the barrier layer 11 perpendicular to the film surface. As described above, the reference layer 12 has a laminated ferrimagnetic structure, and the magnetization of one ferromagnetic layer of the reference layer 12 and the magnetization of the other ferromagnetic layer are antiferromagnetically coupled to each other, thereby pinning the magnetization of one ferromagnetic layer of the reference layer 12 and the magnetization of the other ferromagnetic layer in the perpendicular direction. In this way, the magnetization of the reference layer 12 is pinned in the perpendicular direction. Note that the magnetization of one ferromagnetic layer of the reference layer 12 and the magnetization of the other ferromagnetic layer may be antiferromagnetically coupled by interlayer interaction to pin the magnetization direction.

[0033] In this embodiment, the magnetization M12 of the reference layer 12 is fixed downward, but this is not limited thereto. The magnetization M12 of the reference layer 12 may be fixed upward. When the reference layer 12 has a laminated ferrimagnetic structure as described above, the magnetization of one ferromagnetic layer of the reference layer 12 may be fixed downward, and the magnetization of the other ferromagnetic layer may be fixed upward. Alternatively, the magnetization of one ferromagnetic layer of the reference layer 12 may be fixed upward, and the magnetization of the other ferromagnetic layer may be fixed downward. Furthermore, the magnetization directions of the one ferromagnetic layer and the other ferromagnetic layer of the reference layer 12 may be perpendicular by magnetocrystalline anisotropy or shape magnetic anisotropy, and the magnetization of the one ferromagnetic layer and the magnetization of the other ferromagnetic layer may be antiferromagnetically coupled by interlayer interaction to fix the magnetization direction, so that the magnetization directions of the one ferromagnetic layer and the other ferromagnetic layer may be fixed in the perpendicular direction.

[0034] One ferromagnetic layer and the other ferromagnetic layer of the reference layer 12 can be formed of the same material as the recording layer 10, and the nonmagnetic layer constituting the reference layer 12 can be formed of Ir, Rh, Ru, Os, Re, or alloys thereof such as RuIr, RuRh, RuFe, etc. The nonmagnetic layer is formed to a thickness of about 0.4 nm to 1.0 nm for Ru, 0.4 nm to 0.7 nm for Ir, 0.7 nm to 1.0 nm for Rh, 0.75 nm to 1.2 nm for Os, and 0.5 nm to 0.95 nm for Re. For example, the reference layer 12 is formed from the one ferromagnetic layer: barrier layer 11 side to a thickness of CoFeB(1.2 nm) / W(0.3 nm) / Co(0.5 nm) / (Pt(0.8 nm) / Co(0.25 nm)). 3 / (Pt(0.25nm) / Co(0.5nm)) 2 , non-magnetic layer: Ru (0.85 nm), other ferromagnetic layer: Co 0.5 nm / (Pt 0.25 nm / Co 0.5 nm) from the non-magnetic layer side 7 By using Co-Fe-B for one of the ferromagnetic layers, the magnetization direction of the other ferromagnetic layer can be made perpendicular due to the interface magnetic anisotropy. 3 " after the parentheses in the statement " 3" means that the Pt(0.8nm) / Co(0.25nm) bilayer film is laminated three times (i.e., a total of six layers). "(Pt(0.25nm) / Co(0.5nm) 2 " 2 ", (Pt0.25nm / Co0.5nm) 7 " 7 The same applies to ".

[0035] One ferromagnetic layer may be a three-layer film, as described above, in which a ferromagnetic layer (about 0.6 nm to 2.0 nm) made of CoFeB, FeB, CoB, etc., a nonmagnetic layer (1.0 nm or less) containing Ta, W, Mo, etc., and a ferromagnetic layer are laminated on the barrier layer 11 in this order. The ferromagnetic layers above and below the nonmagnetic layer are ferromagnetically coupled by interlayer interaction. One ferromagnetic layer is configured, for example, as follows: ferromagnetic layer: Co-Fe-B (1.5 nm) / nonmagnetic layer: Ta (0.5 nm) / ferromagnetic layer: crystalline ferromagnetic layer having perpendicular magnetic anisotropy. In this way, the magnetization direction of the ferromagnetic layer becomes perpendicular, and the magnetization direction of the ferromagnetic layer facing each other with the ferromagnetic layer and the nonmagnetic layer sandwiched therebetween also becomes perpendicular, so that the magnetization direction of one ferromagnetic layer can be made perpendicular.

[0036] The cap layer 13 is a layer of about 1.0 nm made of a conductive material such as Ta, and is formed adjacent to the reference layer 12. The magnetic memory element 100 does not necessarily have to have the cap layer 13. The cap layer 13 may be made of a non-magnetic layer such as MgO. In this case, for example, a tunnel current is caused to flow through the cap layer 13, so that a current flows from the third terminal T3 to the reference layer 12.

[0037] Such a magnetic memory element 100 is fabricated by laminating a barrier layer 11, a reference layer 12, and a cap layer 13 in this order on the recording layer 10 of the magnetic laminated film 1 by a general film formation method such as PVD (Physical Vapor Deposition), and then performing a heat treatment at a temperature of about 300° C. to 400° C. Alternatively, the recording layer 10, the barrier layer 11, the reference layer 12, and the cap layer 13 may be formed in this order on the entire surface of the heavy metal layer 2, and an MTJ may be formed by molding the MTJ by a lithography technique or the like.

[0038] Furthermore, three terminals (a first terminal T1, a second terminal T2, and a third terminal T3) are connected to the magnetic memory element 100 for performing write and read operations by applying a voltage or passing a current. The magnetic memory element 100 is a three-terminal element. The first terminal T1, the second terminal T2, and the third terminal T3 are members made of a conductive metal such as Cu, Al, W, or Au, and their shapes are not particularly limited.

[0039] The first terminal T1 and the second terminal T2 are provided at one end and the other end of the heavy metal layer 2 such that an MTJ is disposed between the two terminals. In this embodiment, the first terminal T1 is provided on the surface of one end of the heavy metal layer 2 in the first direction, and the second terminal T2 is provided on the surface of the other end of the heavy metal layer 2 in the first direction. A first transistor Tr1 of an FET type is connected to the first terminal T1, and the second terminal T2 is connected to the ground. The first transistor Tr1 has, for example, a drain connected to the first terminal T1 and a source connected to a first bit line, and is supplied with a write voltage V w The transistor 11 is connected to a write power supply that supplies a write current, and the gate is connected to a word line.

[0040] The write power supply supplies a voltage level to the write voltage V w By turning on the first transistor Tr1, the write voltage V w can be applied to the first terminal T1, and a write voltage V w The write current I w For example, the write voltage Vw By making the value of I higher than ground, a write current I flows from the first terminal T1 to the second terminal T2. w and write voltage V w By lowering the value of below ground, a write current I w In this manner, the first terminal T1 and the second terminal T2 are connected to the heavy metal layer 2 (one end and the other end), and a write current I w Flush.

[0041] The third terminal T3 is provided on the cap layer 13 in contact with the cap layer 13. In this embodiment, the third terminal T3 is a cylindrical thin film whose cross section cut in the in-plane direction has the same circular shape as the MTJ, is disposed on the upper surface of the MTJ (cap layer 13), covers the entire upper surface, and is electrically connected to the reference layer 12 via the cap layer 13. Also, in this embodiment, a third transistor Tr3 of an FET type is connected to the third terminal T3. The third transistor Tr3 has, for example, a drain connected to the third terminal T3 and a source connected to the second bit line to receive a read voltage V Read The read power supply supplies a voltage level to the second bit line, and the gate is connected to a read voltage line. Read By turning on the third transistor Tr3, the read voltage V Read can be applied.

[0042] In addition, by turning on the first transistor Tr1 and the third transistor Tr3, a read current I is generated between the first terminal T1 and the third terminal T3 to read the resistance value of the MTJ according to the potential difference between the first terminal T1 and the third terminal T3. r For example, V w V Read By setting it higher, a read current I r can be flushed.

[0043] In this embodiment, the first terminal T1 and the second terminal T2 are provided on the upper part of the heavy metal layer 2 (the surface on which the MTJ is provided) so that contact is made with the magnetic memory element 100 from above, but this is not limited thereto. For example, the first terminal T1 and the second terminal T2 may be provided adjacent to the buffer layer 4 provided on the lower part of the heavy metal layer 2 (adjacent to the surface behind the surface on which the MTJ is provided), so that contact is made with the magnetic memory element 100 from below. In addition, the second terminal T2 may be connected to a third bit line via a second transistor Tr2, rather than to the ground, and a write current I may be supplied in accordance with the potential difference between the first terminal T1 and the second terminal T2 connected to the first bit line. w In this case, for example, the first bit line is set to a high level, the third bit line is set to a low level, and the potential of the first terminal T1 is made higher than the potential of the second terminal T2, so that a write current I flows from the first terminal T1 to the second terminal T2. w Then, the first bit line is set to a low level, the third bit line is set to a high level, and the potential of the second terminal T2 is made higher than the potential of the first terminal T1, so that a write current I w During readout, the second transistor Tr2 is turned off, thereby preventing a readout current from flowing to the second terminal T2.

[0044] (1-3) Methods for writing and reading data from magnetic memory elements A method of writing to such a magnetic memory element 100 will be described with reference to FIGS. 3, 4, 5, and 6, in which the same components as those in FIG. 1 are assigned the same numbers. In the magnetic memory element 100, the resistance of the MTJ changes depending on whether the magnetization directions of the recording layer 10 and the reference layer 12 are parallel or antiparallel. When the reference layer 12 is a laminated film, the resistance of the MTJ changes depending on whether the magnetization direction of the recording layer 10 and the magnetization direction of the ferromagnetic layer of the reference layer 12 in contact with the barrier layer 11 are parallel or antiparallel. When the recording layer 10 is also a laminated film, the resistance of the MTJ changes depending on whether the magnetization direction of the ferromagnetic layer in contact with the barrier layer 11 of the recording layer 10 and the magnetization direction of the ferromagnetic layer in contact with the barrier layer 11 of the reference layer 12 are parallel or antiparallel.

[0045] In this specification, when it is said that the recording layer 10 and the reference layer 12 are in a parallel state, it also includes a state in which the recording layer 10 or the reference layer 12 is a laminated film, and the magnetization direction of the ferromagnetic layer in contact with the barrier layer 11 of the recording layer 10 is parallel to the magnetization direction of the ferromagnetic layer in contact with the barrier layer 11 of the reference layer 12. When it is said that the recording layer 10 and the reference layer 12 are in an antiparallel state, it refers to a state in which the recording layer 10 or the reference layer 12 is a laminated film, and the magnetization direction of the ferromagnetic layer in contact with the barrier layer 11 of the recording layer 10 is antiparallel to the magnetization direction of the ferromagnetic layer in contact with the barrier layer 11 of the reference layer 12.

[0046] In the magnetic memory element 100, the resistance value of the MTJ is different between the parallel state and the antiparallel state, and one bit of data, "0" and "1", is assigned to the parallel state and the antiparallel state to store data in the magnetic memory element 100. Since the magnetization direction of the recording layer 10 of the magnetic memory element 100 is reversible, the magnetization state of the MTJ is transitioned between the parallel state and the antiparallel state by reversing the magnetization direction of the recording layer 10, and "1" is stored in the MTJ (hereinafter also referred to as a bit) that has stored "0", and "0" is stored in the bit that has stored "1". In this specification, changing the resistance value of the MTJ by reversing the magnetization direction of the recording layer 10 in this manner is also referred to as writing data.

[0047] A more specific description will be given of the writing method of the magnetic memory element 100. In this embodiment, the heavy metal layer 2 is formed of an amorphous layer having a structure in which a first layer containing Hf and a second layer containing a heavy metal other than Hf are alternately laminated, and elements that are less than half, such as Hf, Ta, W, Re, Os or alloys thereof, have a negative spin Hall angle. Therefore, an example will be described in which the spin Hall angle of the heavy metal layer 2 is negative. In addition, an external magnetic field H is applied in the x direction (longitudinal direction of the heavy metal layer 2) by a magnetic field generating device (not shown). 0 can be applied.

[0048] First, a case where data "0" is written to the magnetic memory element 100 storing data "1" will be described. In this case, in the initial state, as shown in FIG. 3, the magnetic memory element 100 stores data "1", the magnetization direction of the recording layer 10 is upward, the magnetization direction of the ferromagnetic layer in contact with the barrier layer 11 of the reference layer 12 is downward, and the MTJ is in an anti-parallel state. Also, it is assumed that the first transistor Tr1 and the third transistor Tr3 are turned off. First, an external magnetic field H 0 is applied.

[0049] Next, as shown in FIG. 4 (which shows the magnetization direction of the recording layer 10 after writing), the first transistor Tr1 is turned on, and a write voltage V w At this time, the write voltage V w is set higher than the ground voltage, so that the write current I w flows from one end of the heavy metal layer 2 to the other end in the +x direction, and a write current I w Since the third transistor Tr3 is off, no current flows from the first terminal T1 to the third terminal T3 via the MTJ. In this embodiment, the write current I w flows between one end and the other end of the heavy metal layer 2. The write current I w is a pulse current, and the pulse width can be changed by adjusting the time that the first transistor Tr1 is turned on.

[0050] Write current I to heavy metal layer 2 w When this current flows, a spin current (flow of spin angular motion) is generated in the heavy metal layer 2 by the spin Hall effect due to spin-orbit interaction, and spins facing toward the front side of the page (-y direction in FIG. 1) flow toward the upper surface side (+z direction) of the heavy metal layer 2, while spins facing toward the back side of the page (+y direction in FIG. 1) and anti-parallel to the spins flow toward the lower surface side (-z direction) of the heavy metal layer 2, resulting in uneven distribution of spins in the heavy metal layer 2. Then, the spin current flowing through the heavy metal layer 2 causes the spins facing in the -y direction to flow into the recording layer 10.

[0051] At this time, in the ferromagnetic layer of the recording layer 10, a torque in the +x direction acts on the magnetization M10 due to the inflow of spins, and the magnetization M10 rotates in the +x direction due to the torque, and the upward magnetization M10 is reversed to a downward magnetization, and the MTJ becomes parallel. 0 is applied in the +x direction, so the external magnetic field H 0 The torque due to the spin is cancelled out by this, so that the magnetization M10 does not rotate any further and remains oriented in the -z direction. After that, by turning off the first transistor Tr1 and stopping the write current, the magnetization M10 is fixed in the -z direction and data "0" is stored.

[0052] Next, a case where data "1" is written to the magnetic memory element 100 storing data "0" will be described.

[0053] In this case, in the initial state, the magnetic memory element 100 stores data "0", the magnetization direction of the recording layer 10 is downward, the magnetization direction of the ferromagnetic layer in contact with the barrier layer 11 of the reference layer 12 is downward, and the MTJ is in a parallel state. The first transistor Tr1 and the third transistor Tr3 are turned off. First, an external magnetic field H 0 is applied.

[0054] Next, as shown in FIG. 6 (which shows the magnetization direction of the recording layer 10 after writing), the first transistor Tr1 is turned on, and a write voltage V w At this time, the write voltage V w is set lower than the ground voltage, the write current I w flows from one end of the heavy metal layer 2 to the other end in the -x direction, and a write current I w flows.

[0055] Write current I to heavy metal layer 2 wWhen this current flows, a spin current (flow of spin angular motion) is generated in the heavy metal layer 2 due to the spin Hall effect caused by spin-orbit interaction, and spins facing into the page (+y direction in Figure 1) flow toward the upper surface (+z direction) of the heavy metal layer 2, while spins that are anti-parallel to the spins and facing toward the front of the page (-y direction in Figure 1) flow toward the lower surface (-z direction) of the heavy metal layer 2. As a result, the spins are unevenly distributed within the heavy metal layer 2. The spin current flowing through the heavy metal layer 2 causes the spins facing in the +y direction to flow into the recording layer 10.

[0056] At this time, in the ferromagnetic layer of the recording layer 10, a torque in the -x direction acts on the magnetization M10 due to the inflow of spins, and the torque rotates the magnetization M10 in the -x direction, and the downward magnetization M10 is reversed to become upward, and the MTJ is in an anti-parallel state. 0 is applied in the +x direction, so the external magnetic field H 0 The torque due to the spin is cancelled out by this, so the magnetization M10 does not rotate any further and remains oriented in the +z direction. Then, by turning off the first transistor Tr1 and stopping the write current, the magnetization M10 is fixed in the +z direction and data "1" is stored. In this way, the write current I w By passing a current through the recording layer 10, the magnetization of the recording layer 10 is reversed, and data can be rewritten.

[0057] In this manner, in the magnetic memory element 100, a write current I w By passing a current, the magnetization direction of the recording layer 10 of the MTJ can be reversed, and data "0" or data "1" can be written.

[0058] In addition, the magnetic memory element 100 may be configured so that the magnetization M10 of the recording layer 10 is reversed by spins injected from the heavy metal layer 2 by applying a voltage between one end (first terminal T1) and the other end (second terminal T2) of the heavy metal layer 2 to pass a write current through the heavy metal layer 2, and by applying a voltage to the MTJ via the third terminal T3 to reduce the magnetic anisotropy of the ferromagnetic layer of the recording layer 10.

[0059] In the above example, an external magnetic field H 0 However, the present invention is not limited to this. For example, by devising the above-mentioned voltage application method or the shape of the MTJ described later, the external magnetic field generating device is not necessarily required.

[0060] Next, the read method will be explained with reference to FIG. 7. At this time, in the initial state, all the transistors are turned off. First, the write voltage V w Read out the voltage V Read Next, the read operation is performed by turning on the first transistor Tr1 and the third transistor Tr3 and applying the write voltage V w and the readout voltage V Read At this time, the write voltage V w is the read voltage V Read Since the read current I r The read current I r flows through the barrier layer 11. The read current I r is detected by a current detector (not shown). r Since the magnitude of the read current I r From the magnitude of the read current I, it is possible to determine whether the MTJ is in a parallel or antiparallel state, i.e., whether the MTJ is storing data "0" or data "1." r is a pulse current, and the pulse width is adjusted by adjusting the time when the third transistor Tr3 is turned on.

[0061] The read current I r is the read current I r When the MTJ current I r It is desirable to set the current to a level low enough that the recording layer 10 does not undergo spin-transfer magnetization reversal due to the write voltage V w and the read voltage V ReadBy appropriately adjusting the potential difference, the read current I r Also, the first transistor Tr1 is turned on to adjust the magnitude of the write voltage V w Then, turn on the third transistor Tr3 to generate the read voltage V Read In this way, it is possible to prevent a current from flowing from the third terminal T3 through the MTJ to the second terminal T2, and it is possible to prevent a current other than the read current from flowing through the MTJ.

[0062] Then, after the third transistor Tr3 is turned off, the first transistor Tr1 is turned off. By turning off the first transistor Tr1 after the third transistor Tr3, that is, the write voltage V w Read out the voltage V Read By turning it off later, a read voltage V Read Therefore, the magnetic memory element 100 can protect the barrier layer 11, further reduce the thickness of the barrier layer 11, and further suppress the read disturbance caused by the current flowing through the MTJ changing the magnetization state of the recording layer 10.

[0063] (1-4) Action and Effects As described above, the magnetic laminated film 1 of the first embodiment is a laminated film for a magnetic memory element, and is configured to include an amorphous heavy metal layer having a structure in which a first layer containing Hf and a second layer containing a heavy metal other than Hf are alternately laminated, and a recording layer including a ferromagnetic layer whose magnetization direction is reversible and adjacent to the heavy metal layer.

[0064] Therefore, in the magnetic laminated film 1, the heavy metal layer 2 is composed of an amorphous layer having a structure in which a first layer containing Hf and a second layer containing a heavy metal other than Hf are alternately laminated, so that the electrical resistivity of the heavy metal layer can be made lower than that of β-W, and power consumption can be suppressed. Also, the roughness of the heavy metal layer can be made smaller than that of β-W, and the variation in MTJ characteristics can be suppressed.

[0065] (Verification experiment) (Preparation of Example Samples and Comparative Example Samples) In order to carry out the following verification experiment, a sample having a magnetic laminated film 1S with the configuration shown in FIG. 8 was created. The magnetic laminated film 1S is a film in which a substrate 5, a buffer layer 4, a heavy metal layer 2, a recording layer 10, a barrier layer 11, and a conductive layer 20 are laminated, and has an x-direction extending portion and three y-direction extending portions intersecting the x-direction extending portion. The width of each portion is 5.8 μm, and the interval (pitch) between the multiple y-direction extending portions is 205 μm. As shown in FIG. 8, when an external magnetic field is applied, a magnetic field Hy in the y direction or a magnetic field Hz in the z direction is applied. A current is passed between both ends of the x-direction extending portion, and a predetermined voltage V is measured at the ends of the y-direction extending portions at the center and at the ends.

[0066] FIG. 9 is a schematic cross-sectional view of a sample of a comparative example. FIG. 10 is a schematic cross-sectional view of samples of Examples 1 and 2. FIG. 11 is a schematic cross-sectional view of a sample of Example 3. As the magnetic laminated film 1S constituting the samples according to Examples 1 to 3 or the comparative example, a high resistance Si substrate was used as the substrate 5, and Ta (thickness 0.5 nm) was formed as the buffer layer 4. In the sample of Example 1, an amorphous film (W / Hf) (thickness 1.4 nm to 7.0 nm) was formed as the heavy metal layer 2 by alternately stacking a first layer (thickness 0.35 nm) of Hf and a second layer (thickness 0.35 nm) of W. In the sample of Example 2, an amorphous film (W / Hf) (thickness 1.4 nm to 7.0 nm) was formed as the heavy metal layer 2 by alternately stacking a first layer (thickness 0.7 nm) of Hf and a second layer (thickness 0.7 nm) of W. In the sample of Example 3, an amorphous film (W-Ta / Hf) (thickness 1.4 nm to 7.0 nm) was formed as the heavy metal layer 2, in which a first layer of Hf (thickness 0.7 nm) and a second layer of W-Ta (thickness 0.7 nm) were alternately laminated. In the sample of the comparative example, a β-phase W film (β-W) (thickness 1.4 nm to 7.0 nm) was formed as the heavy metal layer 2a. In Examples 1 to 3 and the comparative example, CoFeB (1.5 nm) was formed as the recording layer 10, and further an MgO layer (1.0 nm) was formed as the barrier layer 11, and further a Ta layer (1.0 nm) was formed as the conductive layer 20.

[0067] In the magnetic laminated film 1S of Examples 1 to 3 and Comparative Example, MgO is formed as a barrier layer on the CoFeB layer as the recording layer, creating a state similar to that when used as a magnetic memory element. Furthermore, a conductive layer made of Ta equivalent to a cap layer is formed on the MgO layer to prevent the state of the MgO layer from changing due to oxygen in the atmosphere, etc. Such magnetic laminated film 1S of Examples 1 to 3 and Comparative Example has a natural oxide film of SiO 2 The layers were fabricated by successively depositing each layer on a Si substrate with layers formed thereon by rf magnetron sputtering.

[0068] The heavy metal layer 2 in each of Examples 1 and 2 is an amorphous layer (W / Hf) produced by alternately laminating a hafnium layer (formed at an argon gas pressure of 0.3 Pa) as an Hf layer (first layer) and a tungsten layer (formed at two conditions of argon gas pressures of 2.55 Pa and 0.3 Pa) as a W layer (second layer), laminating a conductive layer made of a Ta layer, and then heat treating the layer at 300°C. The heavy metal layer 2 in Example 3 is an amorphous layer (W-Ta / Hf) produced by forming a W-Ta layer instead of the W layer (second layer) in the above-mentioned method for forming the heavy metal layer 2. The heavy metal layer 2a in the comparative example is β-phase W (β-W) produced by forming only the W layer (second layer) at an argon gas pressure of 2.55 Pa without forming the Hf layer (first layer) in the above-mentioned method for forming the heavy metal layer 2.

[0069] Furthermore, the (W / Hf) was produced under two different conditions, with the W gas pressure being changed, and both were confirmed to be amorphous by cross-sectional TEM, and the properties shown below were found to match within the margin of error. By being sandwiched between amorphous Hf, heavy metals other than Hf, such as W and W-Ta, also become amorphous, and it is believed that the properties are the same because the same substances are produced regardless of the gas pressure.

[0070] (Verification experiment 1) In verification experiment 1, TEM images of the cross sections of the samples of Example 1, Example 3, and Comparative Example were taken. FIG. 12 is a TEM image of the cross section of the sample of the Comparative Example. A buffer layer (Ta), a heavy metal layer (W), a recording layer (CoFeB), a barrier layer (MgO), and a conductive layer (Ta) are laminated on a substrate (Substrate). The heavy metal layer (W) is β-phase W (β-W). If the thickness of the heavy metal layer (W) exceeds 3 nm, the roughness becomes worse. The thickness of the heavy metal layer (W) shown in FIG. 12 is 7 nm. Since the roughness of the heavy metal layer (W) is poor, the roughness of the interface of the layer above the heavy metal layer (W) becomes worse. It can be seen that the barrier layer (MgO) also has a low (100) crystal orientation.

[0071] FIG. 13 is a TEM image of a cross section of the sample of Example 1. A buffer layer (Ta), a heavy metal layer (W / Hf), a recording layer (CoFeB), a barrier layer (MgO), and a conductive layer (Ta) are laminated on a substrate (Substrate). The heavy metal layer (W / Hf) is amorphous. The thickness of the heavy metal layer (W / Hf) is about 7 nm, which is more than 3 nm, but compared to FIG. 12, the surface roughness of the heavy metal layer (W / Hf) is good and the flatness is high. Since the roughness of the heavy metal layer (W / Hf) is good, the interface roughness of the layer above the heavy metal layer (W / Hf) is also good and the flatness is high. At this time, the recording layer (CoFeB) is amorphous. The barrier layer (MgO) was formed assuming a film thickness of 1.0 nm, but was actually 0.9 nm. It can be seen that it is a crystalline film showing a clear MgO (100) crystal orientation.

[0072] FIG. 14 is a TEM image of a cross section of the sample of Example 3. A buffer layer (Ta), a heavy metal layer (W-Ta / Hf), a recording layer (CoFeB), a barrier layer (MgO), and a conductive layer (Ta) are laminated on a substrate (Substrate). The heavy metal layer (W-Ta / Hf) is amorphous. The thickness of the heavy metal layer (W-Ta / Hf) is about 7 nm, which is more than 3 nm, but compared to FIG. 12, the surface roughness of the heavy metal layer (W-Ta / Hf) is good and the flatness is high. Since the roughness of the heavy metal layer (W-Ta / Hf) is good, the interface of the layer above the heavy metal layer (W-Ta / Hf) is also good and the flatness is high. At this time, the recording layer (CoFeB) is amorphous. The barrier layer (MgO) was formed assuming a film thickness of 1.0 nm, but was actually 0.9 nm. It is clear that the film is crystalline and exhibits a clear MgO(100) crystal orientation.

[0073] (Verification experiment 2) In verification experiment 2, samples with different heavy metal layer thicknesses t (nm) were prepared for Example 1, Example 2, Example 3, and Comparative Example, and their conductance G XX (Ω -1 ) was measured and the dependence on the thickness t (nm) of the heavy metal layer was calculated. XX (Ω -1 ) on the thickness t (nm) of the heavy metal layer, the electrical resistivity ρ XX (Ωcm) was calculated.

[0074] FIG. 15 is a graph showing the dependence of conductance on the thickness of the heavy metal layer in verification experiment 2. In FIG. 15, the conductance of each of Example 1 (Hf(0.35 nm) / W(0.35 nm), symbol ◯), Example 2 (Hf(0.7 nm) / W(0.7 nm), symbol ◇), Example 3 (Hf(0.7 nm) / W-Ta(0.7 nm), symbol ■) and Comparative Example (β-W, symbol △) is shown. It was confirmed that the slope of the graphs of Examples 1 to 3 was larger than the slope of the graph of the Comparative Example. The samples of Example 1, Example 2, Example 3 and Comparative Example, which have different heavy metal layer thicknesses t (nm), have a common structure in the parts other than the heavy metal layer, so the difference between the graphs of Examples 1 to 3 and the graph of the Comparative Example is the characteristics brought about by the heavy metal layer.

[0075] The electrical resistivity ρ of the heavy metal layer of each sample in Example 1, Example 2, Example 3, and Comparative Example was calculated by calculating the reciprocal of the slope of the graph showing the dependence of the conductance on the thickness of the heavy metal layer in Verification Experiment 2 in FIG. XX (μΩcm) was obtained. FIG. 16 is a graph showing the electrical resistivity of verification experiment 2. The electrical resistivity of the heavy metal layer (β-W) of the comparative example was 217.2 μΩcm. The electrical resistivity of the heavy metal layer (Hf(0.35nm) / W(0.35nm)) of Example 1 was 176.3 to 181.2 μΩcm. The electrical resistivity of the heavy metal layer (Hf(0.7nm) / W(0.7nm)) of Example 2 was 184.0 μΩcm. The electrical resistivity of the heavy metal layer (Hf(0.7nm) / W-Ta(0.7nm)) of Example 3 was 187.7 μΩcm. It was confirmed that the samples of Examples 1 to 3 all had lower electrical resistivity than the sample of the comparative example.

[0076] (Verification experiment 3) In the verification experiment 3, the electrical resistance R of the samples of Example 1, Example 2, Example 3, and Comparative Example XX The dependence of the resistance (Ω) on the external magnetic field H (Oe) was obtained. FIG. 17 is a graph showing the dependence of the resistance of the sample of Example 2 (Hf(0.7 nm) / W(0.7 nm) on the external magnetic field. The external magnetic field H is a magnetic field Hy in the y direction or a magnetic field Hz in the z direction. As the external magnetic field H increases from 0 in the y direction or z direction, the electrical resistance R XXbecomes larger. Here, the external magnetic field dependence of the resistance shows anisotropy with respect to the direction of the external magnetic field. That is, the external magnetic field dependence of the resistance differs when the direction of the external magnetic field is the y direction and when the direction of the external magnetic field is the z direction. In FIG. 17, the symbol ◆ indicates the external magnetic field dependence when the direction of the external magnetic field is the z direction. Also, in FIG. 17, the symbol ◇ indicates the external magnetic field dependence when the direction of the external magnetic field is the y direction. FIG. 18 shows the external magnetic field dependence of the resistance of the sample of Example 3 (Hf(0.7 nm) / W-Ta(0.7 nm)), where the symbol ◆ indicates the external magnetic field dependence when the direction of the external magnetic field is the z direction and the symbol ◇ indicates the external magnetic field dependence when the direction of the external magnetic field is the y direction.

[0077] Electrical resistance R of the samples of Example 1, Example 2, Example 3 and Comparative Example XX From the dependence of the external magnetic field H(Oe) on the spin Hall magnetoresistance ratio (ΔR XX / R XX H=0 ) (%) is obtained. The spin Hall magnetoresistance ratio (ΔR XX / R XX H=0 ) is the difference in resistance ΔR when an external magnetic field is applied in the y and z directions. XX The electrical resistance R when the external magnetic field is zero XX H=0 The ratio (%) of the spin Hall magnetoresistance ratio (ΔR XX / R XX H=0 19 is a graph showing the dependence of the spin Hall magnetoresistance ratio (%) on the thickness t (nm) of the heavy metal layer. In Fig. 19, the spin Hall magnetoresistance ratios of Example 1 (Hf(0.35nm) / W(0.35nm), symbol ◯), Example 2 (Hf(0.7nm) / W(0.7nm), symbol ◇), Example 3 (Hf(0.7nm) / W-Ta(0.7nm), symbol ■) and Comparative Example (β-W, symbol △) are shown. In Examples 1 to 3, the peak position is on the thinner side of the film thickness, indicating that the spin diffusion length is shorter.

[0078] (Verification experiment 4) In verification experiment 4, the spin generation efficiency θ of the samples of Example 1, Example 2, Example 3, and Comparative Example was calculated by fitting the data of FIG. 19 with the equation of the diffusion model. SHThe solid line and various dotted lines in FIG. 19 are the results of fitting, and it can be seen that they reproduce the data well. FIG. 20 is a graph showing the spin generation efficiency. The vertical axis of FIG. 20 is the absolute value of the spin generation efficiency |θ SH It was confirmed that the spin generation efficiency of the sample of Comparative Example (β-W) was about 0.2, whereas the spin generation efficiency of the samples of Examples 1 to 3 was a high value comparable to that of the Comparative Example.

[0079] (Verification experiment 5) In verification experiment 5, the spin diffusion lengths λ of the samples of Example 1, Example 2, Example 3, and Comparative Example were S 21 is a graph showing the spin diffusion length in Verification Experiment 5. The spin diffusion length in the heavy metal layer (β-W) of the sample of the comparative example was about 1 nm, but the spin diffusion length in the samples of Examples 1 to 3 was about 0.6 nm.

[0080] (Verification experiment 6) In the verification experiment 6, the magnetic anisotropy constant K eff and the effective thickness of the recording layer (ferromagnetic layer) t * The product of was evaluated using a VSM (Vibrating Sample Magnetometer). The magnetic anisotropy constant K eff and effective film thickness t * The results of the product are shown in Fig. 22. In Fig. 22, the horizontal axis is the thickness t (nm) of the recording layer (ferromagnetic layer). In Fig. 22, graphs of Example 1 (Hf (0.35 nm) / W (0.35 nm), symbol ◯), Example 2 (Hf (0.7 nm) / W (0.7 nm), symbol ◇), Example 3 (Hf (0.7 nm) / W-Ta (0.7 nm), symbol ■), and Comparative Example (β-W, symbol △) are shown.

[0081] In FIG. 22, the magnetic anisotropy constant K eff and the effective thickness of the recording layer (ferromagnetic layer) t * In the region where the product of is positive, the magnetization direction is perpendicular to the magnetic field. eff and the effective thickness of the recording layer (ferromagnetic layer) t *In the region where the product is negative, it indicates that the ferromagnetic layer has an in-plane magnetization direction. From FIG. 22, it was confirmed that in the comparative example, the film thickness of the recording layer (ferromagnetic layer) must be thinned to 1 nm or less in order to obtain a film that can be magnetized in the perpendicular direction. The graphs of Examples 1 to 3 are shifted in the positive direction of the vertical axis compared to the graph of the comparative example. In other words, it is shown that a film that can be magnetized in the perpendicular direction can be obtained even if the film thickness of the recording layer (ferromagnetic layer) is thickened to about 1.4 nm.

[0082] In each of the above verification experiments, the electrical resistivity (μΩcm), spin generation efficiency (spin Hall angle) proportional to 1 / Js, and relative power consumption (when the comparative example β-W is set to 1) for each heavy metal layer material are summarized in Table 1. The heavy metal layer materials are Example 1 (Hf (0.35 nm) / W (0.35 nm)), Example 2 (Hf (0.7 nm) / W (0.7 nm)), Example 3 (Hf (0.7 nm) / W-Ta (0.7 nm)), and the comparative example (β-W).

[0083] [Table 1]

[0084] (2) Second embodiment (2-1) Overall configuration of the magnetic memory element according to the second embodiment With reference to Fig. 23A, a magnetic memory element 100A according to a second embodiment of the present invention will be described. Fig. 23A is a plan view showing a columnar MTJ as an example of a magnetic memory element. The MTJ of the magnetic memory element 100A is substantially cylindrical, and a notch portion NA is provided in a portion from the outer circumferential surface of the substantially cylindrical shape to the inside. As shown in Fig. 23A, the notch portion NA has a shape in the plan view of the MTJ that is suitable for the write current I wThe cutout portion NA is provided at a position asymmetrical with respect to any line along the direction. The surface of the MTJ at the cutout portion NA has a shape that is convex in the circumferential direction of a substantially cylindrical shape. FIG. 23B is a plan view showing a columnar MTJ of another example of the magnetic memory element according to the second embodiment of the present invention. As in the magnetic memory element 100A shown in FIG. 23A, the cutout portion NA may be sized to be provided in a range from the third quadrant to the second quadrant and the fourth quadrant, or as in the magnetic memory element 100AX shown in FIG. 23B, the cutout portion NA may be sized to be provided only in the third quadrant. Although an example in which the cutout portion NA is mainly missing in the third quadrant is shown in FIGS. 23A and 23B, any one of the first quadrant, the second quadrant, the third quadrant, and the fourth quadrant may be missing.

[0085] FIG. 23C is a perspective view showing the magnetic memory element 100A shown in FIG. 23A. As shown in FIG. 23C, the magnetic laminated film 1A includes an amorphous heavy metal layer 2 having a structure in which a first layer containing Hf and a second layer containing a heavy metal other than Hf are alternately laminated, and a recording layer 10A provided adjacent to the heavy metal layer 2. In this embodiment, the heavy metal layer 2 has a rectangular parallelepiped shape stretched in the first direction (x direction) and has a rectangular shape when viewed from above. The configuration of the heavy metal layer 2 is the same as that of the first embodiment. The magnetic memory element 100AX shown in FIG. 23B also has a similar configuration, so the magnetic memory element 100A will be representatively described below.

[0086] In this embodiment, the heavy metal layer 2 is, for example, Si or SiO 2 The heavy metal layer 2 is provided on a substrate 5 formed of, for example, Ta. The substrate 5 has a buffer layer 4 formed of, for example, Ta, provided on one surface. The heavy metal layer 2 is provided adjacent to this buffer layer 4.

[0087] The recording layer 10A is formed adjacent to the surface of the heavy metal layer 2 opposite to the surface adjacent to the buffer layer 4. The recording layer 10A is formed of a ferromagnetic layer whose magnetization direction is reversible. Adjacent to the surface of the recording layer 10A opposite to the surface adjacent to the heavy metal layer 2, a barrier layer 11A, a reference layer 12A, and a conductive layer 13A are laminated in this order, and a third terminal T3A is provided connected to the conductive layer 13A. In addition, a first terminal T1 and a second terminal T2 are provided and connected to the heavy metal layer 2. The laminate of the recording layer 10A, the barrier layer 11A, the reference layer 12A, the conductive layer 13A, and the third terminal T3A has a substantially cylindrical shape with a notch portion NA.

[0088] As described above, the shape of the stack of the recording layer 10A, the barrier layer 11A, and the reference layer 12A, as viewed from the opposite side to the heavy metal layer 2, is w The materials and film thicknesses of the recording layer 10A, the barrier layer 11A, the reference layer 12A, the conductive layer 13A and the third terminal T3A are the same as those in the first embodiment.

[0089] The writing and reading methods of the magnetic memory element 100A can be performed in the same manner as in the first embodiment. Here, the shape of the stack of the recording layer 10A, the barrier layer 11A, and the reference layer 12A as described above, as viewed from the opposite side of the heavy metal layer 2, is w By being asymmetric with respect to any line along the direction, it is possible to reverse the magnetization direction during writing even in the absence of an external magnetic field.

[0090] (2-2) Overall configuration of magnetic memory 24 is a schematic perspective view showing an example of a magnetic memory using an array of the magnetic memory elements 100A of FIG. 1 Five magnetic memory elements M 11 ~M 51 Common substrate SA 1 is a laminate of a substrate 5, a buffer layer 4 and a heavy metal layer 2, and five magnetic memory elements M 11 ~M 51 The substrate is common to the five magnetic memory elements M11 ~M 51 Each of the common substrates SA is formed of a laminate of a recording layer 10A, a barrier layer 11A, a reference layer 12A, a conductive layer 13A, and a third terminal T3A, and has a substantially cylindrical shape with a notch. 1 The common substrate SA has a first terminal (not shown) at one end in the longitudinal direction to which a write voltage can be applied via a transistor, and a second terminal (not shown) at the other end is connected to ground via a transistor. 2 Five magnetic memory elements M 12 ~M 52 Also, a common substrate SA 3 Five magnetic memory elements M 13 ~M 53 Common substrate SA 1 ~SA 3 are arranged in parallel. This is an array in which 5 × 3 magnetic memory elements are integrated. Although the drawing shows an array of 5 × 3 magnetic memory elements, this is not limited to this, and the present invention can be applied to an array in which m × n magnetic memory elements are integrated.

[0091] The magnetic memory is a magnetic memory element M 11 ~M 53 The write section has a write power source for writing data to the heavy metal layer 2. The write section supplies a write current I w By passing the current through the magnetic memory element M 11 ~M 53 Write data to.

[0092] The magnetic memory includes a read power supply and a current detector, and includes a magnetic memory element M 11 ~M 53 The read power supply supplies a read current I r The current detector detects a read current I r Detecting the magnetic memory element M 11 ~M 53 Read the data written in

[0093] The above magnetic memory element M 11 ~M 53 A method of writing data to the recording layer 10A of each MTJ will be described below. Here, a case will be described in which the ground is directly connected to the second terminal T2 of the heavy metal layer 2, but the second terminal T2 may be connected to the ground via a transistor. In the initial state, the transistors connected to the first terminal T1 of the heavy metal layer 2 and the transistors connected to the third terminal T3A of each MTJ are all off. First, all the transistors connected to the third terminal T3A of each MTJ are turned on to reduce the magnetic anisotropy of the recording layer 10A of each MTJ. Next, a write voltage V w is set to a positive voltage, turning on the transistor connected to the first terminal T1 and causing a write current I w is passed from the first terminal T1 to the second terminal T2. This causes 0 to be written to all MTJs at once. After that, all the transistors connected to the third terminal T3A of each MTJ are turned off, and the transistor connected to the first terminal T1 is turned off.

[0094] Next, the transistor connected to the third terminal T3A of the MTJ to which 1 is to be written is turned on to select the MTJ to be written. Then, the write voltage V w is set to a negative voltage, the transistor connected to the first terminal is turned on, and a write current I w flows. Only the MTJ with the transistor connected to the third terminal T3A turned on has small magnetic anisotropy in the recording layer 10A, and so magnetization is reversed. As a result, a 1 is written only to the selected MTJ. After that, all transistors connected to the third terminal T3A are turned off, and the transistor connected to the first terminal T1 is turned off to end the write operation. Note that after 1s are written to all MTJs at once, a 0 may be written only to the selected MTJ. In addition, a read operation is performed by turning on the transistor connected to the first terminal T1, then turning on the transistor connected to the third terminal T3A of the MTJ to be read, and passing a read current I r The subsequent read operation is the same as in the first embodiment, and therefore will not be described.

[0095] As described above, the magnetic laminated film 1A of the second embodiment is a laminated film for a magnetic memory element, and is configured to include an amorphous heavy metal layer having a structure in which a first layer containing Hf and a second layer containing a heavy metal other than Hf are alternately laminated, and a ferromagnetic layer whose magnetization direction is reversible, and a recording layer adjacent to the heavy metal layer.

[0096] Therefore, in the magnetic laminated film 1A, the heavy metal layer 2 is composed of an amorphous layer having a structure in which a first layer containing Hf and a second layer containing a heavy metal other than Hf are alternately laminated, so that the electrical resistivity of the heavy metal layer can be made lower than that of β-W, and power consumption can be suppressed. Also, the roughness of the heavy metal layer can be made smaller than that of β-W, and the variation in MTJ characteristics can be suppressed.

[0097] (Variation 1) 25A is a plan view showing a columnar MTJ of another example of the magnetic memory element according to the second embodiment of the present invention. In the columnar MTJ of the other example of the magnetic memory element shown in FIGS. 23A to 23C, the surface of the MTJ at the notch portion NA has a shape that is convex in the outer circumferential direction of a substantially cylindrical shape, but the present invention is not limited to this. As in the magnetic memory element 100B shown in FIG. 25A, the notch portion NB may be a flat surface. Even in this configuration, the shape of the notch portion NB in ​​the plan view of the MTJ is such that the write current I w The notch NB is provided at a position that is asymmetric with respect to any line in the direction along the line. Fig. 25B is a plan view showing a columnar MTJ of another example of the magnetic memory element according to the second embodiment of the present invention. As in the magnetic memory element 100B shown in Fig. 25A, the notch NB may be sized to be provided in a range from the third quadrant to the second and fourth quadrants, or as in the magnetic memory element 100BX shown in Fig. 25B, the notch NB may be sized to be provided only in the third quadrant.

[0098] 26A is a plan view showing a columnar MTJ of another example of the magnetic memory element according to the second embodiment of the present invention. As in the magnetic memory element 100C shown in FIG. 26A, the surface of the MTJ at the notch portion NC may have a shape that is concave in the outer circumferential direction of a substantially cylindrical shape. Even in this configuration, the notch portion NC has a shape in the plan view of the MTJ that is in line with the write current I w The cutout portion NC may be provided in a position that is asymmetric with respect to any line in the direction along the line 100. As in the magnetic memory element 100C shown in Fig. 26A, the cutout portion NC may be provided in a range from the third quadrant to the second and fourth quadrants, or may be provided only in the third quadrant as in the magnetic memory element 100CX shown in Fig. 26B.

[0099] (3) Third embodiment (3-1) Overall configuration of the magnetic memory element according to the third embodiment Hereinafter, a magnetic memory element 100D according to a third embodiment of the present invention will be described with reference to Figs. 27A and 27B. Fig. 27A is a plan view showing a columnar MTJ as an example of a magnetic memory element. The MTJ of the magnetic memory element 100D is substantially cylindrical. Unlike the MTJ shown in Figs. 23A and 23B, no notch is provided. As shown in Fig. 27A, the shape of the MTJ in the plan view corresponds to the write current I w In Fig. 27A, the shape of the MTJ in a plan view is a circle, and the MTJ is symmetrical with respect to a line passing through the center of the circle.

[0100] Fig. 27B is a perspective view showing the magnetic memory element 100D shown in Fig. 27A. As shown in Fig. 27B, the magnetic laminated film 1D includes an amorphous heavy metal layer 2 having a structure in which a first layer containing Hf and a second layer containing a heavy metal other than Hf are alternately laminated, and a recording layer 10D provided adjacent to the heavy metal layer 2. In this embodiment, the heavy metal layer 2 has a rectangular parallelepiped shape stretched in the first direction (x direction) and has a rectangular shape when viewed from above. The configuration of the heavy metal layer 2 is the same as that of the first embodiment.

[0101] In this embodiment, the heavy metal layer 2 is, for example, Si or SiO 2The heavy metal layer 2 is provided on a substrate 5 formed of, for example, Ta. The substrate 5 has a buffer layer 4 formed of, for example, Ta, provided on one surface. The heavy metal layer 2 is provided adjacent to this buffer layer 4.

[0102] The recording layer 10D is formed adjacent to the surface of the heavy metal layer 2 opposite to the surface adjacent to the buffer layer 4. The recording layer 10D is formed of a ferromagnetic layer whose magnetization direction is reversible. Adjacent to the surface of the recording layer 10D opposite to the surface adjacent to the heavy metal layer 2, a barrier layer 11D, a reference layer 12D, and a conductive layer 13D are laminated in this order, and a third terminal T3D is provided connected to the conductive layer 13D. In addition, a first terminal T1 and a second terminal T2 are provided and connected to the heavy metal layer 2. The laminate of the recording layer 10D, the barrier layer 11D, the reference layer 12D, the conductive layer 13D, and the third terminal T3D has an approximately cylindrical shape.

[0103] As described above, the shape of the stack of the recording layer 10D, the barrier layer 11D, and the reference layer 12D, as viewed from the opposite side to the heavy metal layer 2, is w The materials and film thicknesses of the recording layer 10D, the barrier layer 11D, the reference layer 12D, the conductive layer 13D and the third terminal T3D are the same as those in the first embodiment.

[0104] A method of writing to the magnetic memory element 100D will be described. Here, a method of writing to the magnetic memory element 100D when applied to an artificial intelligence system as described later will be described. In the initial state, the transistors connected to the first terminal T1 of the heavy metal layer 2 and the transistors connected to the third terminals T3D of each MTJ are all off. The write voltage V w is set to a positive voltage, turning on the transistor connected to the first terminal T1 and causing a write current I w is applied from the first terminal T1 to the second terminal T2. As a result, since the magnetic anisotropy constant of the MTJ is small, the recording layer 10 having perpendicular magnetization rotates and the axis of easy magnetization is not determined in a stable direction. Next, all the transistors connected to the third terminal T3D of each MTJ are turned on to supply the write auxiliary current I WAis passed, and writing is performed only at each of the passed locations. After that, all the transistors connected to the third terminals T3D of the MTJs are turned off, and the transistors connected to the first terminals T1 are turned off.

[0105] Next, the write voltage V w is set to a negative voltage, the transistor connected to the first terminal T1 is turned on, and a write current I w When the magnetic anisotropy constant Δ of the recording layer 10D is set to a value in the range of 5 to 15, the write current I w When the write auxiliary current I WA When a write assist current I WA When the element is used as a cross-point memory of a crossbar network, the magnetic anisotropy constant Δ of the recording layer 10D is set to a value in the range of 5 to 15, and the write current I w When a current flows, the recording layer 10D having perpendicular magnetization rotates and the axis of easy magnetization is not determined in a stable direction, but this is written by the annular magnetic field application wiring described later. In this case, since the magnetic anisotropy constant Δ of the recording layer 10D is small at 5 to 15, it is possible to write with a small current magnetic field.

[0106] 28 is a timing chart of a signal for writing data to the magnetic memory element 100D. w and the write auxiliary current I WA is a pulse current. As shown in FIG. 28, the write current I w Pulse and write auxiliary current I WA The pulses of the write current I w The pulse is turned on first, and the write current I w Before the pulse is turned off, the write auxiliary current I WAAfter this, the write current I w The pulse is turned off and the write auxiliary current I WA The pulse is turned off.

[0107] Alternatively, after writing 1 to all MTJs at once, 0 may be written to only the selected MTJ. In addition, the read operation is performed by turning on the transistor connected to the first terminal T1, turning on the transistor connected to the third terminal T3D of the MTJ to be read, and supplying a read current I r This is done by pouring the water.

[0108] The method of reading from the magnetic memory element 100D is the same as in the first embodiment, and therefore a description thereof will be omitted.

[0109] As described above, the magnetic laminated film 1D of the third embodiment is a laminated film for a magnetic memory element, and is configured to include an amorphous heavy metal layer having a structure in which a first layer containing Hf and a second layer containing a heavy metal other than Hf are alternately laminated, and a ferromagnetic layer whose magnetization direction is reversible, and a recording layer adjacent to the heavy metal layer.

[0110] Therefore, in the magnetic laminated film 1D, the heavy metal layer 2 is composed of an amorphous layer having a structure in which a first layer containing Hf and a second layer containing a heavy metal other than Hf are alternately laminated, so that the electrical resistivity of the heavy metal layer can be made lower than that of β-W, and power consumption can be suppressed. Also, the roughness of the heavy metal layer can be made smaller than that of β-W, and the variation in MTJ characteristics can be suppressed.

[0111] (3-2) Overall structure of the artificial intelligence (AI) system FIG. 29 is a schematic perspective view showing an example of an AI system using the magnetic memory element according to the third embodiment of the present invention. 1 ···S n ) and a plurality of second wirings (B 1 B m ) and the first wiring (S 1 ···Sn ) and the second wiring (B 1 B m ) at each intersection with the first wiring (S 1 ···S n ) and the second wiring (B 1 B m ) and the cross point memory (CM 11 ···CM mn ) is provided. Crosspoint memory (CM 11 ···CM mn ) is composed of memory elements such as ReRAM (resistance change memory), PCM (phase change memory), MTJ, etc. In this way, a resistive crossbar network is provided.

[0112] The first wiring (S 1 ···S n ) is connected to an input line INPUT, and the other end is connected to an electronic neuron (NR 1 ··NR n ) are connected. Electronic neurons (NR 1 ··NR n ) is a neuronal substrate (SA NR1 ···SA NRn ) on the neuronal substrate (SA NR1 ···SA NRn ) is a laminate of a substrate 5, a buffer layer 4 and a heavy metal layer 2. 1 ··NR n ) has the same configuration as the magnetic memory element 100D. NR1 ···SA NRn ) is connected to the output line OUTPUT.

[0113] The magnetic memory element 100D described above is an electronic neuron (NR 1 ··NR n ) is used in the neuronal substrate (SA NR1 ···SA NRnThe heavy metal layer 2 provided in the crosspoint memory (CM) is composed of an amorphous layer having a structure in which a first layer containing Hf and a second layer containing heavy metals other than Hf are alternately laminated. The above-mentioned resistive crossbar network is regarded as one stage, and multiple stages are connected, so that the output of the resistive crossbar network in the previous stage is input to the resistive crossbar network in the next stage. In this manner, the AI ​​system of this embodiment is constructed. The above-mentioned crosspoint memory (CM) is composed of an amorphous layer having a structure in which a first layer containing Hf and a second layer containing heavy metals other than Hf are alternately laminated. The above-mentioned resistive crossbar network is regarded as one stage, and multiple stages are connected, so that the output of the resistive crossbar network in the previous stage is input to the resistive crossbar network in the next stage. 11 ···CM mn )(CM 11 ···CM mn ) corresponds to the synapse in an AI system.

[0114] Crosspoint Memory (CM 11 ···CM mn ) stores data in a pair of memories corresponding to a pair of second wirings. For example, when an input is received from the previous stage resistive crossbar network, the second wiring B 1 VS is input to the second wire B 2 In response to this, the cross point memory CM 11 and cross point memory CM 21 The data is stored in the cross point memory CM. 31 and crosspoint memory CM 41 The subsequent crosspoint memories also store data according to the input from the previous stage resistive crossbar network. 11 ···CM m1 The same first wiring S 1 Cross point memory CM 11 ···CM m1 The signal is the weighted sum of the data stored in each cross point memory CM 11 ···CM m1 The signal corresponding to the sum of the read currents from the electronic neuron NR 1 The other second wiring B m Similarly, in the crosspoint memory CM 1n ···CMmn The data is stored in the cross point memory CM 1n ···CM mn The signal of the weighted sum of the data stored in the electronic neuron NR n The output is stored in the electronic neuron (NR 1 ··NR n ) is configured to be input to the next stage of the resistive crossbar network.

[0115] FIG. 30 is a circuit diagram of an example of an AI system using a magnetic memory element. n The reference element REF is connected in series with the electronic neuron NR n The reference element REF is a transistor TR SIG Through the power supply voltage V DD is input, and the electronic neuron NR n is connected to ground. A read enable signal SIG is input to the transistor TR SIG When turned on, the reference element REF is supplied with the power supply voltage V DD is entered.

[0116] In the above configuration, the electronic neuron NR n When the value of 1 is stored and the resistance is high, the electronic neuron NR n The output from the connection point of the reference element REF becomes high potential, and the high potential signal passes through the amplifier AMP and is input to the transistor TR +VS and transistor TR -VS The +VS and -VS signals are input to the next stage resistor crossbar network NW n+1 is entered into

[0117] In the above configuration, the electronic neuron NR n When the value of 0 is stored and the resistance is low, the electronic neuron NR n The output from the connection point of the reference element REF becomes low potential, and the low potential signal passes through the amplifier AMP to the transistor TR +VSand transistor TR -VS As a result, the +VS and -VS signals are input to the next stage resistive crossbar network NW n+1 is not entered.

[0118] As described above, the magnetic memory element of this embodiment is used to configure an AI system in which the output of a previous stage resistive crossbar network is input to a next stage resistive crossbar network.

[0119] (Variation 2) FIG. 31 is a schematic perspective view showing another example of an AI system using a magnetic memory element. Electronic Neuron (NR 1 ··NR n ) has the same configuration as the magnetic memory element 100D, and in addition, 11 ···CM mn The cross point memory (CM) has the same configuration as the magnetic memory element 100D. 11 ···CM mn The first wiring on which the SA 1 ···SA n ) and is composed of a laminate of a substrate 5, a buffer layer 4 and a heavy metal layer 2. 1 ···SA n The heavy metal layer 2 provided on the substrate 1 is composed of an amorphous layer having a structure in which a first layer containing Hf and a second layer containing a heavy metal other than Hf are alternately laminated.

[0120] As described above, the magnetic memory element of this embodiment is used to configure an AI system in which the output of a previous stage resistive crossbar network is input to a next stage resistive crossbar network.

[0121] (Variation 3) FIG. 32 is a plan view of another example of an AI system using magnetic memory elements. In the array of magnetic memory elements constituting the AI ​​system of the third embodiment described above, magnetic field application electrodes (CL1, CL2, . . .) that can select a specific row for writing and apply a specific magnetic field to the selected row may be provided. 1 ~SA n ) at the position where the magnetic memory element to be written is located, and a write current I w When a voltage is applied to the magnetic element, the thermal stability constant is small, so the magnetic element is in a state where "1" and "0" are not defined. In this state, for example, a current is passed in a specified direction through the magnetic field application electrodes (CL1, CL2, ...), which are circular wiring, to generate a magnetic field in a specified direction in the inner region of the ring, thereby performing writing. Figure 32 shows the structure of the common substrate (SA 1 ···SA n ) and Cross Point Memory CM 11 ,CM 21 ···CM 1n ,CM 2n In order to clarify the arrangement of the magnetic field applying electrodes (CL1, CL2, . . . ) relative to the positions of the second wiring and the magnetic field applying electrodes (CL2, CL3, . . . ) the drawings have been simplified by omitting the illustration of other members such as the second wiring.

[0122] FIG. 33 is a plan view of another example of an AI system using magnetic memory elements. In FIG. 32, the magnetic field applying electrodes (CL1, CL2, etc.) are all circular wirings closed at the left side of the drawing, but the configuration is not limited to this. As shown in FIG. 33, the configuration may include a magnetic field applying electrode CL1 which is a circular wiring closed at the left side of the drawing, and a magnetic field applying electrode CL2A which is a circular wiring closed at the right side of the drawing. Both the magnetic field applying electrode CL1 and the magnetic field applying electrode CL2A generate a magnetic field in a predetermined direction in the inner region of the ring by passing a current in a predetermined direction. FIG. 33 shows a configuration of an AI system using magnetic memory elements, in which a common substrate (SA 1 ···SA n ) and cross point memory (CM 11 ,CM 21 ···CM 1n ,CM 2nIn order to clarify the arrangement of the magnetic field applying electrodes (CL1, CL2A...) relative to the positions of the second wiring and the magnetic field applying electrodes (CL2A...), the drawings have been simplified by omitting the illustration of other members such as the second wiring. [Explanation of symbols]

[0123] 1 Magnetic laminated film 2 Heavy metal layer 10 Recording layer 11 Barrier Layer 12 Reference layer 100 Magnetic memory element I w Write Current I r Read Current

Claims

1. A laminated film for a magnetic memory element, an amorphous heavy metal layer having a structure in which a first layer containing Hf and a second layer containing a heavy metal other than Hf are alternately laminated; a recording layer including a ferromagnetic layer whose magnetization direction is reversible and adjacent to the heavy metal layer; Equipped Magnetic laminated film.

2. The second layer contains W or a W alloy. The magnetic laminated film according to claim 1 .

3. The second layer contains one or more elements selected from Co, Fe, and B. The magnetic laminated film according to claim 1 .

4. The layer closest to the recording layer among the heavy metal layers is the first layer.

4. The magnetic laminated film according to claim 1.

5. The thickness of the heavy metal layer is 1.4 nm or more and 9 nm or less.

5. The magnetic laminated film according to claim 1.

6. A magnetic laminated film according to any one of claims 1 to 5, a barrier layer adjacent to the recording layer and made of an insulator; a reference layer adjacent to the barrier layer and having a fixed magnetization direction; Equipped with A write current flowing through the heavy metal layer reverses the magnetization direction of the ferromagnetic layer of the recording layer. Magnetic memory element.

7. a first terminal provided at one end of the heavy metal layer in a longitudinal direction and capable of introducing a current into the heavy metal layer; a second terminal provided at the other end of the heavy metal layer in the longitudinal direction and capable of introducing a current into the heavy metal layer; a third terminal electrically connected to the reference layer; Equipped with The write current flows between the first terminal and the second terminal through the heavy metal layer. The magnetic memory element according to claim 6 .

8. The ferromagnetic layer of the recording layer is magnetized in a direction perpendicular to the film surface.

8. A magnetic memory element according to claim 6 or 7.

9. A magnetic memory element according to any one of claims 6 to 8, a write unit including a write power supply that writes data into the magnetic memory element by passing the write current through the heavy metal layer; a read section including a read power supply that passes a read current that passes through the barrier layer, and a current detector that detects the read current that passes through the barrier layer and reads data written in the magnetic memory element; A magnetic memory comprising:

10. The shape of the stack of the recording layer, the barrier layer and the reference layer, as viewed from the opposite side to the heavy metal layer, is asymmetric with respect to any line along the direction of the write current.

10. The magnetic memory according to claim 9.

11. The magnetic memory element according to any one of claims 6 to 8 is used in an electronic neuron to which the weighted sum of a resistive crossbar network is input. Artificial intelligence system.

12. The magnetic memory elements are further used in the cross-point memory of a resistive crossbar network.

12. The artificial intelligence system of claim 11.

13. The shape of the stack of the recording layer, the barrier layer, and the reference layer, as viewed from the opposite side to the heavy metal layer, is symmetrical with respect to any line in the direction along the write current.

13. An artificial intelligence system according to claim 11 or 12.

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