Magnetic element, magnetic memory, high-frequency oscillator, and method for producing same

Abstract

The present disclosure provides a magnetic element 10 comprising: a wiring layer 11 that has an amorphous structure and contains tungsten and additional element X; and a layered body 12 disposed on the wiring layer and having a magnetic tunnel junction. Also provided are a magnetic memory and a high-frequency oscillator.

Description

Magnetic element, magnetic memory, high frequency oscillator and manufacturing method thereof

[0001] The present disclosure relates to a magnetic element, a magnetic memory, a high-frequency oscillator, and a method for manufacturing the same.

[0002] Due to the explosive increase in the amount of information in recent years, attention has been focused on non-volatile memories that can retain information even when the power is turned off. One example of non-volatile memory is magnetic random access memory (MRAM), which uses the magnetization of micro-magnets as an information medium. As a representative example of a memory cell structure in MRAM, a spin transfer torque magnetoresistive element (STT-MRAM) has been developed, in which a current is applied directly to a magnetic tunnel junction (MTJ), which is a recording element (see, for example, Non-Patent Document 1).

[0003] STT-MRAM requires a large current to be applied to a high-resistance MTJ to write information. Since the read and write paths are the same, there are problems with rewrite durability. Also, high-speed operation is difficult because of the need to prevent erroneous writing.

[0004] As a new MRAM structure that solves these problems, a spin-orbit torque magnetic memory element (SOT-MRAM) that writes information without directly applying current to the MTJ has been proposed (see, for example, Patent Document 1 and Non-Patent Document 2). SOT-MRAM has the advantages of being more durable and capable of high-speed operation than STT-MRAM, and is expected to be applied to cache memories in large-scale integrated circuits.

[0005] SOT-MRAM utilizes the spin Hall effect of the wiring layer connected to the MTJ when writing information. The spin Hall effect is a phenomenon in which a flow of spin angular momentum (so-called spin current) occurs perpendicular to the direction of current when a current is passed through the wiring layer. Examples of spin Hall materials used in the wiring layer include platinum (Pt) and tungsten (W) (see, for example, Non-Patent Documents 3 to 5 and Patent Document 2).

[0006] JP 2022-507841 A JP 2021-150639 A

[0007] Y. Huai, AAPPS Bull., vol. 18, 633 (2008)L. Liu, et al., Science, vol. 336, pp555-558, (2012)IM Miron, et al., Nature, vol. 476, pp189-193, (2012)CF Pai, et al., Appl. Phys. Lett., vol. 101, 12404, (2012)S. Shi, et al., Phys. Rev. Appl. 9, 011002 (2018)

[0008] Platinum, a material used for the wiring layer, is poorly compatible with the crystal structure of the MTJ formed on it, resulting in a poor magnetoresistance effect. Tungsten, which is used as a material for the wiring layer, is considered a promising spin-Hall material because its β-phase (so-called β-W) with an A15 structure has a high spin-Hall effect and can maintain the magnetoresistance effect of the MTJ when an SOT-MRAM is formed. However, because β-W is in a metastable state, there is a problem in that it has poor heat treatment resistance in the semiconductor process of SOT-MRAM.

[0009] The present disclosure provides a magnetic element, a magnetic memory, a high-frequency oscillator, and a method for manufacturing the same, which have a wiring layer made of a new material that has a high spin Hall effect and is highly compatible with a stack having a magnetic tunnel junction formed thereon.

[0010] According to one aspect of the present disclosure, there are provided a magnetic element, a magnetic memory, and a high-frequency oscillator, each including an amorphous wiring layer containing tungsten and an additional element X, and a stack having a magnetic tunnel junction on the wiring layer.

[0011] According to the above aspect, the wiring layer having an amorphous structure containing tungsten and the additive element X has a high spin Hall effect, and since the wiring layer has an amorphous structure, the influence on the crystal structure of the laminate having a magnetic tunnel junction formed thereon is suppressed, thereby improving the compatibility between the wiring layer and the laminate, and making it possible to provide a magnetic element, a magnetic memory, and a high-frequency oscillator having a high magnetoresistance effect.

[0012] According to another aspect of the present disclosure, there is provided a method for manufacturing a magnetic element, the method including the steps of forming a wiring layer having an amorphous structure, the wiring layer being formed using a material source including tungsten and an additional element X, and forming a stack having a magnetic tunnel junction on the wiring layer.

[0013] According to the above aspect, the spin Hall effect is enhanced by forming an amorphous wiring layer containing tungsten and the additive element X, and since the wiring layer has an amorphous structure, the influence on the crystalline structure of the laminate formed thereon is suppressed, thereby providing a method for manufacturing a magnetic element having a high magnetoresistance effect.

[0014] FIG. 1 is a schematic configuration diagram of a magnetic element according to an embodiment; FIG. 2 is an explanatory diagram of the operation of the magnetic element according to an embodiment; FIG. 3 is a schematic configuration diagram of a magnetic element according to another embodiment; FIG. 4 is a schematic configuration diagram of a magnetic element according to a modified example; FIG. 5 is a schematic configuration diagram of a magnetic element according to another modified example; FIG. 6 is a flowchart of a method for manufacturing a magnetic element according to an embodiment; FIG. 7 is a conceptual diagram of co-sputtering using two sputter targets, one of a tungsten W sputter target and one of an additional element X; FIG. 8 is a conceptual diagram of alternate sputtering using two sputter targets, one of a tungsten W sputter target and one of an additional element X; FIG. 9 is a diagram showing an example of structural analysis by thin film X-ray diffraction of the wiring layer of Example 1 according to the magnetic element; FIG. 10 is a diagram showing an example of structural analysis by transmission electron microscope of Example 1; １００－ｙ (Ta ８２ B １８ ) ｙ 1 is a diagram showing the spin Hall effect of a magnetic element formed of a W-type wiring layer according to Example 3; FIG. 2 is a schematic diagram of a circuit for measuring spin current density; FIG. 3 is an example of a ferromagnetic resonance spectrum obtained by measuring spin current density; ９０ B １０ 10 is a graph showing the spin Hall effect when the wiring layer of the magnetic element according to Example 4 is formed of W. １００－ｙ (Mo ８０ B ２０ ) ｙFIG. 10 is a diagram showing the spin Hall effect when formed by the method of Example 10. FIG. 11 is a magnetization curve of Example 5 related to the magnetic element. FIG. 12 is a cross-sectional transmission electron microscope image of Example 6 related to the magnetic memory. FIG. 13 is a magnetoresistance curve of Example 6. FIG. 14 is a magnetoresistance curve of Example 7 related to the magnetic memory. FIG. 15 is a diagram for determining characteristic values ​​of Examples 6 and 7. FIG. 16 is a diagram showing characteristic values ​​of Examples 6 and 7. FIG. 17 is a diagram showing the anomalous Hall effect of Example 8 related to the magnetic memory. FIG. 18 is a schematic diagram of a high-frequency oscillator according to an embodiment. FIG. 19 is an oscillation signal V of Example 9 of the high-frequency oscillator. ＯＳＣ is the frequency spectrum of

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Elements common to multiple drawings are designated by the same reference numerals, and detailed descriptions of those elements will be omitted. The composition of the material of each layer is expressed in atomic percent (at%).

[0016] [Magnetic Element] FIG. 1 is a schematic diagram of a magnetic element according to one embodiment. Referring to FIG. 1 , the magnetic element 10 includes a wiring layer 11, a stack 12 having a magnetic tunnel junction on the wiring layer 11, and an electrode cap layer 13 on the stack 12. The stack 12 is formed by stacking, in order from the wiring layer 11 side, a magnetization free layer 14, a tunnel barrier layer 15, and a reference layer 16, forming a magnetic tunnel junction. When a pulse current is applied between the terminals 11a and 11b connected to the wiring layer 11, a flow of spin angular momentum, i.e., a spin-orbit torque type spin current, is generated in a direction perpendicular to the current direction. This spin current acts on the magnetization of the magnetization free layer 14 of the stack 12, reversing the magnetization direction of the magnetization free layer 14 depending on the polarity and magnetization direction of the spin current. This changes the magnetic resistance between the terminal 13a connected to the electrode cap layer 13 and the terminal 11a or 11b. The wiring layer 11 forms an amorphous alloy of tungsten (W) and an additional element (hereinafter also referred to as "additive element X"), and therefore has a large spin Hall effect, making it possible to reverse the magnetization of the magnetization free layer 14 with low power.

[0017] The magnetization free layer 14 is formed on the wiring layer 11 and is made of a ferromagnetic material. The ferromagnetic material of the magnetization free layer 14 is selected from, for example, Fe—B, Co—Fe—B, Co—Ni—B, Fe—Ni—B, etc. As for the composition, it is preferable that B is selected from the range of 10 at (atomic) % to 40 at %, in order to achieve an amorphous structure that promotes crystallization of the tunnel barrier layer 15. By using a Co—Fe—B film for the magnetization free layer 14, the magnetoresistance ratio of the magnetic element 10 can be made 100% or more. It is preferable that the thickness of the magnetization free layer 14 is set to 0.8 nm to 3 nm, in order to ensure the thermal stability of the magnetization free layer 14 while allowing for write control.

[0018] When no external magnetic field is applied, the magnetization direction of the magnetization free layer 14 may be parallel to the film surface, i.e., in-plane, or perpendicular to the film surface, i.e., perpendicular to the film surface. The magnetization direction of the magnetization free layer 14 is affected by the magnetic field from the magnetization of the magnetization fixed layer of the reference layer 16, exchange interaction, or in-plane shape anisotropy of the magnetization free layer 14, etc.

[0019] The tunnel barrier layer 15 is formed on the magnetization free layer 14 and is made of an insulating material, for example, MgO. The thickness of the tunnel barrier layer 15 is preferably set to 0.8 nm to 2.5 nm, in order to obtain a high magnetoresistance ratio and a high output.

[0020] Reference layer 16 is formed on tunnel barrier layer 15 and is made of a ferromagnetic material. Reference layer 16 is a magnetization fixed layer in which the direction of magnetization is approximately fixed. Examples of ferromagnetic materials that can be used for reference layer 16 include CoFe, Co—Fe—B, Fe—B, a CoPt laminated film, and a CoPd laminated film. The thickness of reference layer 16 is preferably set to 3 nm to 10 nm in order to ensure high thermal stability.

[0021] The electrode cap layer 13 is formed on the reference layer 16 from a conductive material, and is made of, for example, a laminate of a Ta layer and a Ru layer.

[0022] The wiring layer 11 is made of an amorphous alloy of tungsten (W) and an additional element X (hereinafter also referred to as a "W-X alloy"). The additional element X preferably contains at least one element of boron (B), phosphorus (P), and carbon (C) (hereinafter also referred to as an "element NM"), since this allows the wiring layer 11 to maintain an amorphous structure. The additional element X preferably contains at least one metal element of tantalum (Ta) and molybdenum (Mo) (hereinafter referred to as a "metal element M") in addition to at least one element of boron (B), phosphorus (P), and carbon (C) (element NM), since this provides a high spin-Hall angle. The spin-Hall angle is the ratio of the spin current density generated to the unit current density of the pulse current flowing between the terminals 11a and 11b of the wiring layer 11 (i.e., the current value relative to the cross-sectional area of ​​the wiring layer 11 perpendicular to the flow of the pulse current). The spin current density is the spin angular momentum with respect to the surface area in the stacking direction of the wiring layer 11, and can be measured by, for example, spin torque ferromagnetic resonance. The thickness of the wiring layer 11 is preferably set to 3 nm to 20 nm, in order to maximize the spin current injected into the magnetization free layer 14.

[0023] The content of the additional element X in the wiring layer 11 is preferably 5 at % or more, more preferably 10 at % or more, and 50 at % or less, more preferably 40 at % or less, in order to realize a high spin Hall effect against heat treatment. The wiring layer 11 may have a structure in which the content of the additional element X gradually changes from the bottom of the wiring layer 11 to the top, i.e., the magnetization free layer 14, within this preferred range, i.e., a composition gradient structure, and a structure in which the content of the additional element X gradually decreases from the bottom of the wiring layer 11 to the top is more preferable.

[0024] When the wiring layer 11 contains tungsten (W) and the element NM but does not contain the metal element M, it is preferable that the content of the element NM be 5 at% or more and 50 at% or less, in order to maintain an amorphous structure of the wiring layer 11. When the wiring layer 11 contains tungsten (W) and the element NM and the metal element M, it is preferable that the content of the element NM in the additional element X be 10 at% or more, more preferably 15 at% or more, and 50 at% or less, more preferably 45 at% or less, in order to achieve a high spin-Hall angle. Furthermore, in the W-X alloy film, it is preferable that the content of the element NM be 5 at% or more, in order to maintain an amorphous structure against heat treatment.

[0025] FIG. 2 is an explanatory diagram of the operation of a magnetic element according to one embodiment. This is an example in which the magnetic element is used as a magnetic memory. Referring to FIG. 2, the magnetic element 10 includes a wiring layer 11, a cylindrical stack 12 on the wiring layer 11, and an electrode cap layer 13. The wiring layer 11 has two terminals 11a and 11b at both ends in the direction in which a pulse current flows, and the electrode cap layer 13 has a terminal 13a. When reversing the magnetization direction of the magnetization free layer 14 of the stack 12 (e.g., when writing information), a current pulse is passed from one of the terminals 11a and 11b to the other. A spin current flowing perpendicular to the current pulse is generated from the current pulse flowing through the wiring layer 11 and flows upward through the stack 12. The spin current acts on the magnetization of the magnetization free layer 14, reversing the magnetization direction. In this way, information is written into the magnetization free layer 14 of the magnetic memory 10, and when the magnetization direction of the magnetization free layer 14 is the same as the magnetization direction of the reference layer 16 (i.e., parallel), the stack 12 exhibits the lower of the two magnetoresistance values, and when the magnetization direction is different (i.e., antiparallel), the stack 12 exhibits the higher of the two magnetoresistance values.

[0026] When reading information, a pulse current is passed from the terminal 13a, passes through the electrode cap layer 13 and the stack 12, and reaches, for example, the terminal 11b. Information on the magnetization direction of the magnetization free layer 14 is obtained based on the magnitude of the voltage drop between the terminal 13a and the terminal 11b. The operation when reading is the same as that of a conventional spin transfer torque magnetic memory (STT-MRAM).

[0027] 3 is a schematic diagram of a magnetic element according to another embodiment. Referring to FIG. 3 together with FIG. 1, the magnetic element 20 includes a wiring layer 11, a stack 22 having a magnetic tunnel junction on the wiring layer 11, and an electrode cap layer 13 on the stack 22. The stack 22 is formed by stacking, in order from the wiring layer 11 side, a magnetization free layer 14, a tunnel barrier layer 15, and a reference layer 26, forming a magnetic tunnel junction. The reference layer 26 is formed by stacking, in order from the tunnel barrier layer 15 side, a first ferromagnetic layer 31, a nonmagnetic spacer layer 32, a second ferromagnetic layer 33, and an antiferromagnetic layer 34. The magnetic element 20 is similar to the magnetic element 10 shown in FIG. 1, except for the configuration of the reference layer 26.

[0028] The reference layer 26 has a synthetic antiferromagnetic (SAF) structure in which a first ferromagnetic layer 31 and a second ferromagnetic layer 33 are antiferromagnetically coupled with a nonmagnetic spacer layer 32 sandwiched therebetween. The first ferromagnetic layer 31 is antiferromagnetically coupled to the second ferromagnetic layer 33, thereby substantially (practically) fixing the magnetization direction of the first ferromagnetic layer 31. Furthermore, an antiferromagnetic layer 34 is exchange-coupled to the second ferromagnetic layer 33, and the antiferromagnetic layer 34 applies an exchange bias magnetic field to the second ferromagnetic layer 33. This substantially fixes the magnetization direction of the second ferromagnetic layer 33, thereby fixing the magnetization direction of the first ferromagnetic layer 31. The antiferromagnetic layer 34 is not essential.

[0029] The first ferromagnetic layer 31 and the second ferromagnetic layer 33 are set to have a thickness of, for example, 1 nm to 5 nm, and may be made of a ferromagnetic material such as Co--Fe, Co--Fe--B, Fe--B, Co, or CoPt laminated film.

[0030] The nonmagnetic spacer layer 32 has a thickness set to, for example, 0.2 nm to 2 nm, and may be made of a nonmagnetic material such as V, Cr, Cu, Mo, Ru, Rh, Ta, W, Re, or Ir.

[0031] The antiferromagnetic layer 34 has a thickness set to, for example, 5 nm to 10 nm, and can be made of an antiferromagnetic material such as Ir—Mn or Pt—Mn.

[0032] 4A and 4B are schematic configuration diagrams of magnetic elements according to modifications of Fig. 1 and Fig. 3, respectively. Referring to Fig. 4A and Fig. 4B, magnetic elements 40 and 50 have the same configuration as the magnetic element 10 shown in Fig. 1 and the magnetic element 20 shown in Fig. 3, except that a thin film 41 containing a material other than the elements constituting the wiring layer 11 is formed between the wiring layer 11 and the magnetization free layer 14.

[0033] It is preferable that the thin film 41 contains at least one metal element or its oxide selected from the group consisting of Ti, V, Cr, Co—O, Fe—O, Ni—O, Cu, Zr, Nb, Pd, Hf, Ir, Pt, and Au, as this improves the magnetic properties of the magnetization free layer 14, for example, by reducing the anisotropy field, suppressing the magnetic damping constant, and achieving a high spin Hall angle.

[0034] In the magnetic elements 10, 20, 40, and 50, when a pulse current is passed between the terminals 11a and 11b of the wiring layer 11, a flow of spin angular momentum (i.e., spin current) occurs in a direction perpendicular to the current direction, which acts on the magnetization of the magnetization-free layer 14 of the stack 12 and generates a torque that rotates the magnetization. This torque generates a so-called spin-orbit torque. This torque rotates the magnetization of the magnetization-free layer 14 and settles it in an energetically stable direction. When the magnetization of the magnetization-free layer 14 is parallel to the film surface, i.e., the in-plane direction is energetically stable, when a pulse current flows through the wiring layer 11, depending on the polarity of the pulse current and the magnetization direction, the magnetization sometimes rotates 180 degrees (i.e., flips) to face another in-plane direction, or sometimes remains in the same in-plane direction. The wiring layer 11 of this embodiment forms an amorphous alloy of tungsten (W) and the additive element X, and therefore has a large spin Hall effect, making it possible to reverse the magnetization of the magnetization free layer 14 with low power.

[0035] In the magnetic elements 10, 20, 40, and 50, even when the magnetization of the magnetization free layer 14 is perpendicular to the film surface, i.e., the direction perpendicular to the film surface is energetically stable, a spin-orbit torque acts on the magnetization of the magnetization free layer 14, causing the magnetization direction to reverse. An example of the configuration of the magnetic element 10 in which the magnetization of the magnetization free layer 14 is perpendicular to the film surface is as follows. The thickness of each layer is within the preferred range. The example configuration is described in the order in which the layers are stacked on the substrate.

[0036] {Configuration Example 1} Wiring layer 11: W—X alloy, thickness 3 to 20 nm Free magnetization layer 14: Co—Fe—B, thickness 1 to 2 nm Tunnel barrier layer 15: MgO, thickness 0.8 to 2.0 nm Reference layer 26 is a laminate of the following: First ferromagnetic layer 31: Co—Fe—B, thickness 1 to 2 nm Non-magnetic spacer layer 32: W, thickness 0.15 nm Second ferromagnetic layer 33: Co / Pt multilayer film, thickness 2 to 5 nm Non-magnetic spacer layer: Ru or Ir, thickness 0.4 to 0.6 or 0.8 to 1.2 nm Third ferromagnetic layer: Co / Pt multilayer film, thickness 2 to 5 nm Electrode cap layer 13: Ru, Ta, or Pt, thickness 3 to 20 nm

[0037] {Configuration Example 2} Wiring layer 11: W-X alloy, thickness 3 to 20 nm Thin film: Hf, Mo, or Ti, thickness 0.5 to 1.0 nm Free magnetization layer 14: Co-Fe-B, thickness 1 to 2 nm Tunnel barrier layer 15: MgO, thickness 0.8 to 2.0 nm The reference layer 26 and the electrode cap layer 13 are the same as those in Configuration Example 1. The W-X alloy of wiring layer 11 may be a W-X alloy film, which will be described later in the manufacturing method, or a W / X multilayer film.

[0038] In the above configuration examples 1 and 2, the exchange interaction of the Co / Pt multilayer film of the reference layer 26 causes the magnetization of the first ferromagnetic layer 31 to be perpendicular to the film surface, and as a result, the magnetization of the magnetization free layer 14 to be perpendicular to the film surface.

[0039] In the above configuration examples 1 and 2, the magnetization free layer 14 is made of Co—Fe—B, but is not limited to this and may be made of Fe—B, for example. In the magnetic element 10, when the magnetization of the magnetization free layer 14 is perpendicular to the film surface, i.e., in the direction perpendicular to the surface (z direction or −z direction), and is energetically stable, a bias magnetic field may be applied to the magnetization free layer 14 in the direction (x direction) of the pulse current flowing through the wiring layer 11 or in the opposite direction (−x direction). This tilts the magnetization of the magnetization free layer 14 from the z direction or −z direction to the x direction or −x direction by a certain angle (for example, 5°). Depending on the direction of the pulse current flowing through the wiring layer 11, the magnetization of the magnetization free layer 14 reverses from one direction perpendicular to the surface (for example, the z direction) to the opposite direction (for example, the −z direction), or vice versa.

[0040] [Method of Manufacturing Magnetic Element] Fig. 5 is a flowchart of a method of manufacturing a magnetic element according to an embodiment. The method of manufacturing a magnetic element according to an embodiment will be described with reference to Fig. 5 together with Figs.

[0041] First, a substrate is prepared (S100). The substrate is made of a non-magnetic material, and is, for example, a silicon substrate, a silicon substrate with a thermal oxide film, or a gallium arsenide substrate, but is not particularly limited thereto.

[0042] Next, a wiring layer 11 is formed on the substrate (S110). Specifically, a material source containing tungsten and an additive element X, such as a sputtering target containing tungsten W and the additive element X, is prepared. The wiring layer 11 is formed by a sputtering method or the like (the wiring layer 11 formed in this manner is also referred to as a "W-X alloy film"). The additive element X preferably contains at least one element selected from boron (B), phosphorus (P), and carbon (C) (hereinafter also referred to as "element NM"), in order to maintain an amorphous structure of the wiring layer 11. The additive element X preferably contains at least one metal element selected from Ta and Mo in addition to at least one element selected from boron (B), phosphorus (P), and carbon (C) (element NM), in order to achieve a high spin-Hall angle. In the material source containing tungsten and the additive element X, the content of the additive element X is preferably 5 at% or more, more preferably 10 at% or more, and 50 at% or less, more preferably 40 at% or less, in order to achieve a high spin-Hall angle. When the material source contains tungsten (W) and the element NM but does not contain the metal element M, it is preferable that the content of the element NM be 5 at% or more and 50 at% or less, in order to maintain an amorphous structure of the wiring layer 11. When the material source contains tungsten (W) and the element NM and the metal element M, it is preferable that the content of the element NM in the additive element X be 10 at% or more, more preferably 15 at% or more, and 50 at% or less, more preferably 45 at% or less, in order to maintain an amorphous structure against heat treatment of the formed magnetic element. Furthermore, in the W-X alloy film, it is preferable that the content of the element NM be 5 at% or more, in order to maintain an amorphous structure against heat treatment.

[0043] When sputtering is used to form the wiring layer 11, a substrate temperature of 1°C to 50°C is preferable in terms of forming an amorphous structure. The atmospheric gas used is, for example, an inert gas, preferably krypton. The thickness of the wiring layer 11 is preferably set to 3 nm to 20 nm in terms of obtaining a high spin-Hall angle.

[0044] As an alternative method for forming the wiring layer 11 in S110, power may be supplied to two sputtering targets, one of which is a tungsten W sputtering target and the other of which is an additive element X, to simultaneously emit sputter particles from the two sputtering targets, thereby forming the wiring layer 11 (so-called co-sputtering). This allows the formation of a wiring layer 11 made of an amorphous alloy containing tungsten and the additive element X. Alternatively, the wiring layer 11 made of an amorphous alloy containing tungsten and the additive element X may be formed by alternately stacking sputtered particles of tungsten and sputtered particles of the additive element X.

[0045] 6A and 6B are conceptual diagrams for explaining an alternative method for forming the wiring layer 11. Fig. 6A is a conceptual diagram of co-sputtering using two sputter targets, one of which is a tungsten W sputter target and the other of which is an additive element X. Fig. 6B is a conceptual diagram of alternate sputtering using two sputter targets, one of which is a tungsten W sputter target and the other of which is an additive element X.

[0046] 6A, a W—X alloy film is formed by supplying power to two sputtering targets of tungsten and the additional element X, and depositing tungsten sputter particles and additional element X sputter particles by co-sputtering. The composition ratio of the W—X alloy film is controlled by adjusting the sputtering power supplied to each sputtering target.

[0047] Referring to FIG. 6B , tungsten layers and additional element X layers are alternately stacked n times (the wiring layer 11 formed in this manner is also referred to as a “W / X multilayer film”). The thickness of each of the tungsten layer and the additional element X layer is preferably 1.0 nm or less, since this allows the amorphous structure to be maintained during heat treatment. The ratio of the thickness of one additional element X layer to the sum of the thickness tw of one tungsten layer and the thickness tx of one additional element X layer (i.e., tx / (tw+tx)) is preferably 0.10 or more and 0.50 or less. The number of repeated stacking steps n is preferably 3 or more and 20 or less. Although FIG. 6 clearly depicts the boundary between the tungsten layer and the additional element X layer, the thickness of each of the tungsten layer and the additional element X layer in the wiring layer 11 after stacking is very thin and has an amorphous structure, making it difficult to measure the thicknesses tx and tx of each layer. The thicknesses tw and tx of each layer are preferably controlled by determining the deposition rate using a film thickness monitor and controlling the deposition time.

[0048] 5 , next, stacks 12 and 22 having magnetic tunnel junctions are formed on the wiring layer 11 (S120). Specifically, for example, by sputtering, in the example of the magnetic element 10 shown in FIG. 1 , the magnetization free layer 14, the tunnel barrier layer 15, and the reference layer 16 are deposited in this order on the wiring layer 11, and in the example of the magnetic element 20 shown in FIG. 3 , the magnetization free layer 14, the tunnel barrier layer 15, the first ferromagnetic layer 31, the nonmagnetic spacer layer 32, the second ferromagnetic layer 33, and the antiferromagnetic layer 34 of the reference layer 26 are deposited in this order on the wiring layer 11.

[0049] Next, an electrode cap layer is formed (S130). Specifically, a laminate of a Ta layer and a Ru layer is formed on the laminates 12 and 22 by, for example, sputtering.

[0050] Next, the magnetic element formed in S130 may be heat-treated (S140). Specifically, the heat treatment temperature is preferably, for example, 300°C to 420°C, since this improves the magnetic properties of the ferromagnetic layers, such as the magnetization free layer 14 and the reference layer 16, and prevents crystallization of the wiring layer 11. The heat treatment time is preferably 0.5 to 3 hours. The heat treatment may be performed continuously after the magnetic element formed in the steps up to S130, or may be performed after exposing it to the atmosphere. In this manner, the magnetic element is formed.

[0051] 7 is a diagram showing an example of a structure analysis by thin film X-ray diffraction of the wiring layer of Example 1 of the magnetic element, and is an example using the θ-2θ method of thin film X-ray diffraction. The chart of the wiring layer of Example 1 is shown by a solid line, and the chart of the wiring layer of the comparative example is shown by a dashed line. In Example 1, Ta ８０ B ２０ layer (thickness 1 nm), and a W ６７．９ (Ta ８２ B １８ ) ３２．１ (thickness 10 nm), Co—Fe—B (thickness 3 nm) as the magnetization free layer 14, MgO (thickness about 2 nm) as the tunnel barrier layer 15, and Ta—O layer (thickness 2 nm) as the electrode cap layer 13 were laminated in this order. ８０ B ２０ The wiring layer was formed by co-sputtering using a sputtering target of tungsten (W) and Ta. ８２ B １８ The composition ratio (67.9:32.1) of the reference layer 16 was controlled by the sputtering power of each sputtering target. The formation of the reference layer 16 was omitted because it does not affect the structure of the wiring layer. Comparative Example 1 was the same as Example 1, except that the wiring layer was a tungsten layer (crystalline) (thickness 5 nm) of metastable β phase (A15 structure) formed using a tungsten sputtering target.

[0052] Referring to Figure 7, the diffraction pattern of the wiring layer of Example 1 showed no diffraction peaks and a broad halo pattern over the 2θ range of 35° to 45°. This indicates that the wiring layer of Example 1 is in an amorphous state. On the other hand, the wiring layer of Comparative Example 1 shows a diffraction peak at 2θ of around 41°, indicating that it is crystalline. The X-ray diffraction device used was a Malvern Panalytical model X'Pert Pro. Cu-Kα X-rays were used.

[0053] 8A and 8B are diagrams showing an example of structural analysis by a transmission electron microscope in Example 1, which is an example using a transmission electron microscope (TEM). Fig. 8A is a cross-sectional TEM image of Example 1. Figs. 8B and 8C are nanobeam diffraction images of regions 1 and 2 of the wiring layer shown in Fig. 8A, respectively.

[0054] Referring to FIG. 8(a), no crystal planes were observed in the wiring layer of Example 1, and the cross-sectional TEM image showed that no nanocrystals were present. Referring to FIGS. 8(b) and 8(c), no clear disk-shaped diffraction images were observed in the nanobeam diffraction images of Regions 1 and 2 in the wiring layer of Example 1. These findings indicate that the wiring layer of Example 1 is in an amorphous state. The transmission electron microscope used was a NEOARM atomic resolution analytical electron microscope, model JEM-ARM200F, manufactured by JEOL Ltd. The nanobeam diffraction conditions were a camera length of 0.8 m, an acceleration voltage of 200 kV, and a beam diameter on the sample of approximately 5 nm.

[0055] Example 2 Example 2 is a method for forming a Ta film on a substrate. ８２ B １８ layer (thickness 1 nm), and a W １００－ｙ (Ta ８２ B １８ ) ｙ(thickness 5 nm) (y=16, 22.9, 32.1, 42.4, 50.1, 65.6, 77.9, 100), Co—Fe—B (thickness 3 nm) as the magnetization free layer 14, MgO (thickness about 2 nm) as the tunnel barrier layer 15, and Ta—O layer (thickness 2 nm) as the electrode cap layer 13 were laminated in this order. The fixed magnetization layer was omitted because the purpose was to measure the spin Hall effect. The wiring layer 11 was formed by sputtering a tungsten W target and Ta ８０ B ２０ The wiring layer 11 was formed by co-sputtering using a sputtering target of tungsten and Ta. ８２ B １８ The composition ratio (100-y:y) was controlled by the sputtering power. In the magnetic element of Comparative Example 2, the wiring layer 11 was a β-phase tungsten layer (crystalline) (thickness 5 nm), and the other layers were the same as in Example 2.

[0056] FIG. 9 shows a wiring layer of the magnetic element according to the second embodiment. １００－ｙ (Ta ８２ B １８ ) ｙ 9(a) is a graph showing the absolute value of the spin current density ξSHE per unit current density of the current passed through the wiring layer, as a function of the composition of the wiring layer. FIG. 9(b) is a graph showing the absolute value of the spin current density ξSHE per unit electric field of the wiring layer, as a function of the composition of the wiring layer. ＳＨＥ 1 is a diagram showing the absolute value of the spin current density ξ ＳＨＥ The larger the absolute value of , the larger the spin Hall effect, and the smaller the current or electric field required for spin injection into the free magnetization layer. In the figure, black circles (●) and black triangles (▲) represent Example 2, and white circles (○) and white triangles (△) represent Comparative Example 2.

[0057] Referring to FIG. 9A, in Example 2, when y is 16 to 60 at %, the spin current density ξ ＳＨＥ is about 20% or more, and is higher than that of Comparative Example 2 when y is 16 to 40 at %.

[0058] Referring to FIG. 9B, in Example 2, when y is 16 to 60 at %, the spin current density ξ ＳＨＥ The absolute value of is 1 (10 ３ Ω－１ cm －１ ) or more, and it can be seen that the smaller y, i.e., the more tungsten, the higher the value. It can be seen that Example 2 is higher than Comparative Example 2 when y is 16 to 40 at %.

[0059] Spin current density ξ ＳＨＥ was measured by a method using magnetic damping modulation using spin torque ferromagnetic resonance (see, for example, L. Liu et al., Phys. Rev. Lett. 106.036601 (2011)). ＳＨＥ In this study, an external magnetic field was applied at a predetermined angle to the film surface of the magnetization free layer, causing the magnetization of the magnetization free layer to undergo precession due to ferromagnetic resonance, and a direct current was passed through the wiring layer 11 to measure the spin current flowing from the wiring layer 11 to the magnetization free layer 14 from the degree of modulation of the resonance linewidth caused by the spin-orbit torque acting on the magnetization. More specifically, this is as follows.

[0060] 10A is a schematic diagram of a measurement circuit for spin current density. Referring to FIG. 10A, the measurement circuit supplies a DC current I to a thin-wire element 62 formed by shaping a stack of layers to be measured via a bias tee 61. ＤＣ (Keysight Model: B2902A) and microwave current I ＲＦ (Microwave generator: Keysight Model: 5173B EXG-Series) Microwave current I ＲＦ induces ferromagnetic resonance in the free magnetic layer. The ferromagnetic resonance in the free magnetic layer is detected by measuring the voltage VFMR on the DC port side of the bias tee 61 by utilizing the spin torque diode effect. ＦＭＲ In order to improve the measurement accuracy of the microwave current I ＲＦ The voltage was measured using a lock-in amplifier (Stanford Research, Model SR830 DSP Digital Lock-in Amplifier).

[0061] Figure 10B shows an example of a ferromagnetic resonance spectrum obtained by measuring the spin current density. The horizontal axis represents the external magnetic field μH applied in the in-plane direction (μ is the magnetic permeability in a vacuum), and the vertical axis represents the voltage VFMR. The black circles (●) represent the case where a +2 mA DC current is passed through the wiring layer, and the white circles (◯) represent the case where a -2 mA DC current is passed through the wiring layer.

[0062] Referring to FIG. 10B, the ferromagnetic resonance of the magnetization free layer is generated by a rectified voltage V ＦＭＲ is found, and V ＦＭＲ The resonance linewidth W was calculated from the spectral shape of the AC current. ＤＣ flows, and DC current I ＤＣ The change in the resonance linewidth depending on to the spin current density ξ per unit current density ＳＨＥ The spin current density ξ per unit current density was calculated. ＳＨＥ The absolute value of was calculated using the following formula: The above formula are the elementary charge, Dirac constant, gyromagnetic ratio, frequency of the applied AC current (8 GHz), saturation magnetization of the magnetization free layer, film thickness of the magnetization free layer, in-plane angle of the external magnetic field applied to the longitudinal direction of the thin-wire element, resonant magnetic field of the magnetization free layer, effective demagnetizing field of the magnetization free layer 14, thin-wire width of the thin-wire element (3 μm), film thickness of the wiring layer 11, and current split ratio in the wiring layer 11. ξ of the spin current density per unit electric field Ｅ ＳＨＥ The absolute value of was calculated using the following formula: Here, ρ represents the resistivity of the wiring layer.

[0063] Example 3 Example 3 is a method for forming a Ta film on a substrate. ８２ B １８ layer (thickness 1 nm), and a W ９０ B １０ (thickness 5 nm), Co—Fe—B (thickness 3 nm) as the magnetization free layer 14, MgO (thickness about 2 nm) as the tunnel barrier layer 15, and Ta—O layer (thickness 2 nm) as the electrode cap layer 13 were laminated in this order, and then heat-treated at 350° C. for 1 hour. The fixed magnetization layer was omitted because the purpose was to measure the spin Hall effect. The wiring layer 11 was made of W ９０ B１０ The film was formed by sputtering using a sputtering target of the above formula.

[0064] FIG. 11 shows the wiring layer of the magnetic element according to the third embodiment. ９０ B １０ 11A shows the spin Hall effect when the current density ξ per unit current density of the current flowing through the wiring layer is ＳＨＥ 11B is a graph showing the absolute value of the spin current density ξ per unit electric field in the wiring layer. ＳＨＥ 11 shows Comparative Example 2 for comparison.

[0065] Referring to FIG. 11A, in Example 3, the spin current density ξ ＳＨＥ 11B, the absolute value of the spin current density ξ per unit electric field in Example 3 is approximately 31%, which is a high value equivalent to that in Comparative Example 2. ＳＨＥ The absolute value of is 1.5 (10 ３ Ω －１ cm －１ ), which shows a high value equivalent to that of Comparative Example 2. From these, it can be seen that Example 3 has excellent heat resistance to heat treatment and can obtain a high spin Hall angle by forming the wiring layer from a material in which B is added to W.

[0066] Example 4 FIG. 12 shows a wiring layer of a magnetic element according to Example 4. １００－ｙ (Mo ８０ B ２０ ) ｙ 12(a) shows the spin Hall effect when the wiring layer is formed by the composition of the wiring layer, and the spin current density ξ per unit current density of the current passed through the wiring layer. ＳＨＥ 12B is a graph showing the absolute value of the spin current density ξ per unit electric field of the wiring layer as a function of the composition of the wiring layer. ＳＨＥ FIG.

[0067] In Example 4, a W wiring layer 11 was formed on a substrate for measuring the spin Hall effect. １００－ｙ (Mo ８０ B ２０ ) ｙ(thickness 8 nm) (y=10, 14, 20, 25, 30, 35), Co—Fe—B (thickness 3 nm) as the magnetization free layer 14, MgO (thickness about 2 nm) as the tunnel barrier layer 15, and Ta—O layer (thickness 2 nm) as the electrode cap layer 13 were laminated in this order. The fixed magnetization layer was omitted. The wiring layer 11 was formed by sputtering a tungsten (W) target with a Mo ( ８０ B ２０ The wiring layer 11 was formed by co-sputtering a sputtering target of tungsten and Mo. ８０ B ２０ The composition ratio (100-y:y) was controlled by the sputtering power of each sputtering target.

[0068] Referring to FIG. 12(a), in Example 4, when y is 10 to 35 at %, the spin current density ξ ＳＨＥ It can be seen that the absolute value of is about 30% or more.

[0069] Referring to FIG. 12B, in Example 4, when y is 10 to 35 at %, the spin current density ξ ＳＨＥ The absolute value of is 1 (10 ３ Ω －１ cm －１ ) and it can be seen that the smaller y, i.e., the more tungsten there is, the higher the tendency is.

[0070] Example 5 is an example of a magnetic element in which the magnetization of the magnetization free layer is perpendicular to the film surface. Example 5 is an example of a magnetic element in which a wiring layer 11: W is formed on a substrate by a sputtering method. ６７．９ (Ta ８２ B １８ ) ３２．１ (thickness 8 nm), magnetization free layer 14: Fe ８０ B ２０ (thickness 1 nm), tunnel barrier layer 15: MgO (thickness approximately 1.5 nm), first ferromagnetic layer 31: (Fe ９１ Co ９ ) ８０ B ２０(thickness 1 nm), non-magnetic spacer layer 32: W (thickness 0.2 nm), second ferromagnetic layer 33: Co (thickness 0.4 nm) / Pt (thickness 1 nm) and Co (thickness 0.4 nm) / Pt (thickness 0.6 nm) multilayer film (repeated lamination number 3) and Co (thickness 0.3 nm), non-magnetic spacer layer: Ru (thickness 0.47 nm), third ferromagnetic layer: Co (thickness 0.4 nm) / Pt (thickness 0.6 nm) and Co (thickness 0.24 nm) / Pt (thickness 0.36 nm) multilayer film (repeated lamination number 8), electrode cap layer 13: Pt (thickness 3 nm) / Ru (thickness 5 nm) were laminated in this order. The wiring layer 11 was formed by sputtering a tungsten (W) target and a Ta (Ta) target. ８０ B ２０ The sputtering targets were co-sputtered to obtain the desired composition ratio.

[0071] FIG. 13 shows the magnetization curve of the magnetic element of Example 5. The magnetization curve was obtained by applying a magnetic field perpendicular to the film surface of Example 5 and sweeping between -0.4 T and 0.4 T using a vibrating sample magnetometer (VSM, Tamagawa Seisakusho Co., Ltd., Model TM-VSM-211483-HGC). The horizontal axis represents the applied magnetic field, and the vertical axis represents the magnetization. Referring to FIG. 13, the magnetization curve shows a nearly rectangular hysteresis when the applied magnetic field is near 0 T. This indicates that the magnetization of the magnetization free layer of Example 5 is perpendicular to the film surface, and the magnetization is reversed.

[0072] [Magnetic Memory] A magnetic memory according to one embodiment has a configuration similar to that of the magnetic elements 10, 20, 40, and 50 according to the above-described embodiments, i.e., the magnetic elements 10, 20, 40, and 50 shown in FIGS. 1, 3, 4A, and 4B. That is, the magnetic elements 10, 20, 40, and 50 can be used as magnetic memories, and are referred to as magnetic memories 10, 20, 40, and 50, respectively. Referring to FIGS. 1 and 3, the magnetic memory according to the embodiment uses the magnetization free layer 14 of the magnetic elements 10, 20, 40, and 50 shown in FIGS. 1, 3, 4A, and 4B as a recording layer. When writing information to the magnetic memories 10, 20, 40, and 50, a pulse current is passed between the terminals 11a and 11b connected to the wiring layer 11, causing a spin current to flow through the stack 12 and affect the magnetization of the magnetization free layer 14. The magnetization direction of the magnetization free layer 14 is reversed depending on the polarity and magnetization direction of the spin current. This changes the magnetic resistance between the terminal 13a connected to the electrode cap layer 13 and the terminal 11a or 11b, thereby recording information. The magnetic memories 10, 20, 40, and 50 have the same effects as the above-mentioned magnetic elements 10, 20, 40, and 50. The magnetic memories 10, 20, 40, and 50 are manufactured in the same manner as the magnetic elements shown in FIG. 5 and its description.

[0073] As examples of the magnetic memory, examples 6 and 7 were formed. Example 6 In example 6, a W wiring layer 11 was formed on a substrate by sputtering. ６７．９ (Ta ８２ B １８ ) ３２．１ film (thickness 8 nm), and Co as the magnetization free layer 14 １５ Fe ６０ B ２５ film (thickness 1.8 nm), a MgO film (thickness 1.0 to 1.8 nm) as the tunnel barrier layer 15, a first ferromagnetic layer 31: a Co—Fe—B film (thickness 2 nm), a nonmagnetic spacer layer 32: a W film (thickness 0.15 nm), and a second ferromagnetic layer 33: Co ７０ Fe ３０ (thickness 2.0 nm) / Ru (thickness 0.85 nm) / Co ７０ Fe ３０ (thickness 2.5 nm) as a laminate, and Ir as an antiferromagnetic layer 34 ２０ Mn８０ A film (thickness 7 nm) was formed as the electrode cap layer 13, and a laminate of Ru (thickness 3 nm) / Ta (thickness 1 nm) / Ru (thickness 1.5 nm) / Pt (thickness 2 nm) was formed in this order. ６７．９ (Ta ８２ B １８ ) ３２．１ The film is made of W and Ta. ８０ B ２０ The composition ratio (67.9:32.1) was controlled by the sputtering power of each sputtering target.

[0074] Example 7 In Example 7, a W wiring layer 11 was formed on a substrate by sputtering. ６７．９ (Ta ８２ B １８ ) ３２．１ film (thickness 8 nm), and Co as the magnetization free layer 14 １５ Fe ６０ B ２５ film (thickness 1.8 nm), a MgO film (thickness 1.0 to 1.8 nm) as the tunnel barrier layer 15, and a reference layer consisting of a first ferromagnetic layer 31: Co—Fe—B film (thickness 2 nm) / a nonmagnetic spacer layer 32: W film (thickness 0.15 nm) / a second ferromagnetic layer 33: Co ７０ Fe ３０ (thickness 2.0 nm) / Ru (thickness 0.85 nm) / Co ７０ Fe ３０ A stack of Ru (thickness 1.5 nm) / Ta (thickness 4 nm) / Ru (thickness 1.5 nm) / Pt (thickness 2 nm) was formed in this order as the electrode cap layer 13. ７６ (Ta ８０ B ２０ ) ２４ The film is made of W and Ta. ８０ B ２０ The composition ratio (76:24) was controlled by the sputtering power of each sputtering target.

[0075] 14A and 14B are cross-sectional transmission electron microscope images of Example 6 relating to the magnetic memory. FIG. 14A is a cross-sectional transmission electron microscope image of the entire Example 6, and FIG. 14B is a cross-sectional transmission electron microscope image of the wiring layer of Example 6. Referring to FIG. 14A, it can be seen that the reference layer has a crystalline structure, with crystal planes appearing. On the other hand, referring to FIG. 14B, it can be seen that the wiring layer has an amorphous structure, with atoms arranged randomly.

[0076] 15A and 15B show magnetoresistance curves of Example 6. FIG. 15A shows the magnetoresistance value R of the magnetic tunnel junction when the applied magnetic field is swept in the in-plane direction of the magnetization free layer of Example 6. ＭＴＪ 15(b) shows the magnetoresistance curve of the magnetic tunnel junction measured by changing the magnitude of the pulse current flowing through the wiring layer of Example 6. ＭＴＪ The pulse width of the pulse current was set to 100 μsec.

[0077] 15(a), when the applied magnetic field is swept between −4 mT and 4 mT, the magnetoresistance curve of the magnetic tunnel junction of Example 6 changes from A to B to C to D to A. At B (2.6 mT) and D (−1.6 mT), the magnetization free layer 14 (Co １５ Fe ６０ B ２５ It can be seen that the magnetization direction of the free magnetization layer 14, i.e., the recording layer, is reversed, and the magnetoresistance value changes to a low resistance value (13.9 kΩ) and a high resistance value (33.0 kΩ), respectively. This shows that information can be recorded depending on the magnetization direction of the free magnetization layer 14, i.e., the recording layer. Referring to FIG. 15(b), when the current density of the pulse current applied to the wiring layer 11 of Example 6 is −4.8×10 ６ A / cm ２ and 4.4 x 10 ６ A / cm ２ When the magnetic resistance is changed between F (3.3×10), the magnetoresistance curve of the magnetic tunnel junction of Example 6 changes from E to F to G to H to E. ６ A / cm ２ ) and H(-2.7 × 10 ６ A / cm ２ ), the magnetization free layer 14 (Co １５ Fe ６０ B ２５It can be seen that the magnetization direction of the free magnetization layer 14 (film) is reversed, and the magnetoresistance value changes to a high resistance value (33.0 kΩ) and a low resistance value (13.9 kΩ), respectively. This shows that the magnetization of the free magnetization layer 14, i.e., the recording layer, can be reversed by applying a pulse current to the wiring layer 11, thereby recording information.

[0078] 16A and 16B show magnetoresistance curves of the magnetic memory according to Example 7. FIG. 16A shows the magnetoresistance value R of the magnetic tunnel junction when the applied magnetic field is swept in the in-plane direction of the magnetization free layer of Example 7. ＭＴＪ 16(b) shows the magnetoresistance curve of the magnetic tunnel junction measured by changing the magnitude of the pulse current flowing through the wiring layer of Example 7. ＭＴＪ The pulse width of the pulse current was set to 100 μsec.

[0079] 16(a), when the applied magnetic field is swept between −4 mT and 4 mT, the magnetoresistance curve of the magnetic tunnel junction of Example 7 changes from A to B to C to D to A. At B (1.2 mT) and D (−1.5 mT), the magnetization free layer 14 (Co １５ Fe ６０ B ２５ It can be seen that the magnetization direction of the free magnetization layer 14, i.e., the recording layer, is reversed, and the magnetoresistance value changes to a low resistance value (6.1 kΩ) and a high resistance value (14.1 kΩ), respectively. This shows that information can be recorded depending on the magnetization direction of the free magnetization layer 14, i.e., the recording layer. Referring to FIG. 16(b), when the current density of the pulse current applied to the wiring layer 11 of Example 7 is −8×10 ６ A / cm ２ and 8 x 10 ６ A / cm ２ When the magnetic resistance is changed between F (4.7×10), the magnetoresistance curve of the magnetic tunnel junction of Example 7 changes from E to F to G to H to E. ６ A / cm ２ ) and H(-4.3 × 10 ６ A / cm ２ ), the magnetization free layer 14 (Co １５ Fe ６０ B ２５It can be seen that the magnetization direction of the free magnetization layer 14, i.e., the recording layer, is reversed, and the magnetoresistance value changes to a high resistance value (14.1 kΩ) and a low resistance value (6.1 kΩ), respectively. This shows that the magnetization of the free magnetization layer 14, i.e., the recording layer, can be reversed by applying a pulse current to the wiring layer 11, thereby recording information.

[0080] 17 is a diagram for determining the characteristic values ​​of Examples 6 and 7. The horizontal axis of FIG. 17 represents the value (τp / τ0) obtained by dividing the pulse width τp of the pulse current applied to the wiring layer by the reciprocal τ0 of the attempt frequency of 1 GHz. τ0 was set to 1 ns. The vertical axis represents the magnetization free layer 14 (Co １５ Fe ６０ B ２５ The reversal current density j is the density of the pulse current when the magnetization of the film is reversed. ＳＷ In the figure, triangles (△, ▲) represent Example 6, and circles (◯, ●) represent Example 7. ＳＷ and (τp / τ0) can be expressed by the following relational expression. Here, j ｃ０ corresponds to the threshold of the intrinsic switching current density and is an index showing power saving operation. Δ is the thermal stability index of the magnetization free layer, which indicates thermal stability. k Ｂ is the Boltzmann constant, and T is the measurement environment temperature, which is room temperature (300 K) in the measurements of Examples 6 and 7. Referring to FIG. 17, it can be seen that the data points of Examples 6 and 7 can be well fitted to a straight line. From this straight line, j ｃ０ and Δ / (k Ｂ T) was sought.

[0081] FIG. 18 is a diagram showing the characteristic values ​​of Examples 6 and 7. Referring to FIG. 18, in Examples 6 and 7, the jc0 is comparable to that of Non-Patent Documents 5 and 6, in which the wiring layer is made of β-W. The thermal stability index is higher than that of Non-Patent Documents 5 and 6. Furthermore, the heat treatment temperatures are 360°C and 400°C, respectively, which are more than 100°C higher than that of Non-Patent Documents 5 and 6. This shows that Examples 6 and 7 have extremely excellent heat resistance in the semiconductor manufacturing process.

[0082] Example 8 Example 8 of the magnetic memory is an example in which the magnetization of the magnetization free layer is perpendicular to the film surface. Measurement of the anomalous Hall effect showed that the magnetization of the magnetization free layer, which is perpendicular to the film surface, is reversed by the spin flow of a pulse current applied to the wiring layer.

[0083] In Example 8, a W wiring layer 11 was formed on a substrate by sputtering. ６７．９ (Ta ８２ B １８ ) ３２．１ film (thickness 8 nm), and Fe as the magnetization free layer 14 ８０ B ２０ A Ta (thickness 1.4 nm) / Ru (thickness 3 nm) stack was formed in this order as the tunnel barrier layer 15, a MgO film (thickness 1.0-1.2 nm) as the tunnel barrier layer 15, and an electrode cap layer 13. In Example 8, the phenomenon of the magnetization free layer reversal was possible by measuring the anomalous Hall effect even when the reference layer was omitted. However, the reference layer is essential for a magnetic memory. In measuring the anomalous Hall effect, the in-plane direction of the magnetization free layer was the x-direction, the direction in which the wiring layer 11 extended, the y-direction in the same plane perpendicular to the x-direction, and the z-direction perpendicular to the film surface of the magnetization free layer. The Hall coefficient was determined by measuring the voltage in the y-direction.

[0084] 19 is a diagram showing the anomalous Hall effect of Example 8 of the magnetic memory. Figure 19(a) shows the magnetic moment m / S (mA) per unit area relative to the magnitude of the applied magnetic field μH when a magnetic field (Hx) is swept in the in-plane direction (x direction) of the magnetization free layer (dashed line) and when a magnetic field (Hz) is swept in the direction perpendicular to the film surface of the magnetization free layer (z direction) (solid line). Referring to Figure 19(a), when the magnetic field (Hx) is swept in the in-plane direction (x direction) of the magnetization free layer (dashed line), the curve shows a magnetic field applied to the hard axis of magnetization, while when the magnetic field (Hz) is swept in the direction perpendicular to the film surface of the magnetization free layer (z direction), the curve shows a magnetic field applied to the easy axis of magnetization. This shows that the magnetization of the magnetization free layer is perpendicular to the film surface.

[0085] 19(b) shows the Hall coefficient curve when the applied magnetic field (Hz) is swept in the direction perpendicular to the film surface of the magnetization free layer (z direction). Referring to FIG. 19(b), when the magnetic field is applied and swept in the direction perpendicular to the film surface of the magnetization free layer, the hysteresis loop shows high and low Hall coefficients. This shows that the magnetization of the magnetization free layer is perpendicular to the film surface, and the direction is reversed by the application of the magnetic field.

[0086] 19(c) shows the Hall coefficient curve measured by changing the magnitude of the pulse current applied to the wiring layer of Example 8, where a bias magnetic field of 10 mT is applied in the in-plane direction (x direction) of the film surface of the magnetization free layer. Application of the bias magnetic field tilts the magnetization of the magnetization free layer from the z direction to the x direction in the x-z plane. Referring to FIG. 19(c), when the current density of the pulse current applied to the wiring layer 11 of Example 8 is changed to -1.7×10 １１ A / cm ２ and 1.7 x 10 １１ A / cm ２ When the voltage is changed between B (1.16×10), the Hall coefficient curve of the magnetic memory of Example 8 changes from A to B to C to D to A. １１ A / cm ２ ) and D(-0.97 × 10 １１ A / cm ２ ), the magnetization direction of the magnetization free layer is reversed, and the Hall coefficients change to 0.30Ω and −0.30Ω, respectively. This shows that the magnetization of the magnetization free layer, i.e., the recording layer, can be reversed by applying a pulse current to the wiring layer 11, and information can be recorded.

[0087] 19(d) shows the Hall coefficient curve measured by changing the magnitude of the pulse current applied to the wiring layer of Example 8, where a bias magnetic field of 10 mT is applied in the in-plane direction (-x direction) of the film surface of the magnetization free layer. Application of the bias magnetic field tilts the magnetization of the magnetization free layer from the z direction to the -x direction in the x-z plane. Referring to FIG. 19(d), when the current density of the pulse current applied to the wiring layer of Example 8 is changed to -1.7×10 １１ A / cm ２ and 1.7 x 10 １１ A / cm ２When the voltage is changed between F (1.25×10), the Hall coefficient curve of the magnetic memory of Example 8 changes from E to F to G to H to E. １１ A / cm ２ ) and H(-1.17 × 10 １１ A / cm ２ ), the magnetization direction of the magnetization free layer is reversed, and the Hall coefficients change to −0.30Ω and 0.30Ω, respectively. This shows that the magnetization of the magnetization free layer, i.e., the recording layer, can be reversed by applying a pulse current to the wiring layer 11, and information can be recorded.

[0088] [High-Frequency Oscillator] Fig. 20 is a schematic diagram of a high-frequency oscillator according to one embodiment. Referring to Fig. 20, the high-frequency oscillator 60 according to one embodiment is formed by stacking a wiring layer 11, a magnetization free layer 14, a tunnel barrier layer 15, a reference layer 66, and an electrode cap layer 13 on the wiring layer 11. The reference layer 66 is formed by stacking, from the tunnel barrier layer 15 side, a first ferromagnetic layer 31, a non-magnetic spacer layer 32, and a second ferromagnetic layer 33. The high-frequency oscillator 60 has a configuration similar to that of the magnetic elements 10 and 20 according to the above-described embodiments, i.e., the magnetic elements 10 and 20 shown in Figs. 1 and 3. That is, the magnetic elements 10 and 20 can be used as the high-frequency oscillator 60. The high-frequency oscillator 60 has a current I between terminals 11a and 11b connected to the wiring layer 11. ＳＨＥ When current flows through the wiring layer 11, torque due to magnetic damping occurring during precession and spin orbit torque due to the spin current generated by the current flowing through the wiring layer 11 act on the magnetization of the magnetization free layer 14, causing self-oscillation of the magnetization of the magnetization free layer 14. As a result, in the high-frequency oscillator 60, the voltage between the terminal 13a and the terminal 11a or 11b oscillates, and the oscillation signal V ＯＳＣ The high frequency oscillator 60 is manufactured in the same manner as the magnetic element shown in FIG.

[0089] Example 9 Example 9 of the high frequency oscillator was formed under the same film configuration and forming conditions as Example 1 of the magnetic memory. A direct current of −0.8 mA was applied to the wiring layer 11, and an oscillation signal V ＯＳＣ21 shows the frequency spectrum of the oscillation signal V OSC of the high-frequency oscillator according to Example 9. The horizontal axis represents frequency, and the vertical axis represents the oscillation signal V ＯＳＣ 21, the ninth embodiment is a power spectrum density of the oscillation signal V ＯＳＣ It can be seen that the main wavelength component of 1.26 GHz is included.

[0090] Although the preferred embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the present disclosure as defined in the claims.

[0091] The following supplementary notes are further disclosed in relation to the above-described embodiments. (Supplementary Note 1) A magnetic element comprising: a wiring layer having an amorphous structure containing tungsten and an additional element X; and a stacked body having a magnetic tunnel junction on the wiring layer. (Supplementary Note 2) The magnetic element according to Supplementary Note 1, wherein the content of the additional element X in the wiring layer is 5 at% or more and 50 at% or less. (Supplementary Note 3) The magnetic element according to Supplementary Note 1, wherein the additional element X includes at least one element NM selected from B, P, and C. (Supplementary Note 4) The magnetic element according to Supplementary Note 3, wherein the content of the element NM in the wiring layer is 5 at% or more and 50 at% or less. (Supplementary Note 5) The magnetic element according to Supplementary Note 1, wherein the additional element X includes at least one metal element M selected from Ta and Mo, and at least one element NM selected from B, P, and C. (Supplementary Note 6) The magnetic element according to Supplementary Note 5, wherein the content of the element NM in the additional element X in the wiring layer is 10 at% or more and 50 at% or less. (Supplementary Note 7) The magnetic element according to any one of Supplementary Notes 1 to 6, wherein the stack having the magnetic tunnel junction includes a magnetization free layer, and the direction of magnetization of the magnetization free layer is parallel or perpendicular to the film plane of the magnetization free layer when no magnetic field is applied from outside the magnetic element. (Supplementary Note 8) The magnetic element according to Supplementary Note 7, wherein the magnetization free layer is formed directly on the wiring layer or via a thin film containing a material other than the wiring layer. (Supplementary Note 9) The magnetic element according to Supplementary Note 8, wherein the thin film contains at least one metal element or oxide of Ti, V, Cr, Co—O, Fe—O, Ni—O, Cu, Zr, Nb, Pd, Hf, Ir, Pt, and Au. (Supplementary Note 10) A magnetic memory comprising the magnetic element according to any one of Supplementary Notes 1 to 9. (Supplementary Note 11) A high-frequency oscillator comprising the magnetic element according to any one of Supplementary Notes 1 to 9. (Supplementary Note 12) A method for manufacturing a magnetic element, comprising: forming a wiring layer having an amorphous structure, the wiring layer being formed using a material source containing tungsten and an additional element X; and forming a stacked body having a magnetic tunnel junction on the wiring layer. (Supplementary Note 13) The method for manufacturing a magnetic element according to Supplementary Note 12, wherein the additional element X includes at least one element NM selected from the group consisting of B, P, and C.(Supplementary Note 14) The method for manufacturing a magnetic element according to Supplementary Note 12, wherein the additional element X includes at least one metal element M of Ta and Mo, and at least one element NM of B, P, and C. (Supplementary Note 15) The method for manufacturing a magnetic element according to any one of Supplementary Notes 12 to 14, wherein in the step of forming the wiring layer, a first material source including tungsten and a second material source including the additional element X are used. (Supplementary Note 16) The method for manufacturing a magnetic element according to any one of Supplementary Notes 15 to 14, wherein in the step of forming the wiring layer, the wiring layer is formed by simultaneously or alternately releasing and depositing component elements from a first material source including tungsten and a second material source including the additional element X. (Supplementary Note 17) The method for manufacturing a magnetic element according to Supplementary Note 16, wherein in the step of forming the wiring layer, a first material source containing tungsten and a second material source containing the additional element X are alternately released and deposited to form a multilayer film structure in which first layers containing tungsten and second layers containing the additional element X are alternately stacked, and the film thickness of each of the first layer and the second layer is 1.0 nm or less. (Supplementary Note 18) The method for manufacturing a magnetic element according to Supplementary Note 17, wherein a film thickness ratio of the film thickness of the second layer to the sum of the film thickness of the first layer and the film thickness of the second layer, i.e., film thickness ratio = (film thickness of the second layer) / {(film thickness of the first layer) + (film thickness of the second layer)} is 0.10 or more and 0.50 or less. (Supplementary Note 19) A method for manufacturing a magnetic memory, comprising manufacturing the magnetic element according to any one of Supplementary Notes 12 to 18. (Supplementary Note 20) A method for manufacturing a high-frequency oscillator, comprising manufacturing a magnetic element according to any one of Supplementary Notes 12 to 18. This application claims priority to Japanese Patent Application No. 2023-164022, filed September 26, 2023, and Japanese Patent Application No. 2023-212929, filed December 18, 2023. The contents of the specifications and drawings of these applications are incorporated herein by reference in their entirety.

[0092] 10, 20, 40, 50 Magnetic element, magnetic memory 11 Wiring layer 12, 22 Stacked body 14 Magnetization free layer 15 Tunnel barrier layer 16, 26, 66 Reference layer 41 Thin film 60 High frequency oscillator

Claims

1. A magnetic element comprising: a wiring layer having an amorphous structure containing tungsten and an additive element X; and a stack having a magnetic tunnel junction on the wiring layer.

2. The magnetic element according to claim 1, wherein the content of said additional element X in said wiring layer is 5 at % or more and 50 at % or less.

3. The magnetic element according to claim 1, wherein said additional element X includes at least one element NM selected from the group consisting of B, P and C.

4. The magnetic element according to claim 3, wherein the content of said element NM in said wiring layer is 5 at % or more and 50 at % or less.

5. The magnetic element according to claim 1, wherein said additional element X includes at least one metallic element M selected from the group consisting of Ta and Mo, and at least one element NM selected from the group consisting of B, P and C.

6. The magnetic element according to claim 5, wherein the content of said element NM in said additional element X in said wiring layer is 10 at % or more and 50 at % or less.

7. The magnetic element according to claim 1, wherein the stack having the magnetic tunnel junction includes a magnetization free layer, and the direction of magnetization of the magnetization free layer is parallel or perpendicular to the film surface of the magnetization free layer when no magnetic field is applied from outside the magnetic element.

8. The magnetic element according to claim 7, wherein the free magnetization layer is formed directly on the wiring layer or via a thin film containing a material other than the wiring layer.

9. The magnetic element according to claim 8, wherein the thin film contains at least one metal element or oxide of Ti, V, Cr, Co--O, Fe--O, Ni--O, Cu, Zr, Nb, Pd, Hf, Ir, Pt and Au.

10. A magnetic memory comprising a magnetic element according to any one of claims 1 to 9.

11. A high-frequency oscillator comprising a magnetic element according to any one of claims 1 to 9.

12. A method for manufacturing a magnetic element, comprising: a step of forming a wiring layer having an amorphous structure, the step of forming the wiring layer using a material source containing tungsten and an additive element X; and a step of forming a stack having a magnetic tunnel junction on the wiring layer.

13. The method of manufacturing a magnetic element according to claim 12, wherein the additional element X includes at least one element NM selected from the group consisting of B, P and C.

14. The method of manufacturing a magnetic element according to claim 12, wherein the additional element X includes at least one metal element M selected from the group consisting of Ta and Mo, and at least one element NM selected from the group consisting of B, P and C.

15. The method for manufacturing a magnetic element according to claim 12, wherein in the step of forming the wiring layer, a first material source containing tungsten and a second material source containing the additional element X are used.

16. The method for manufacturing a magnetic element according to claim 15, wherein in the step of forming the wiring layer, the wiring layer is formed by simultaneously or alternately releasing and depositing component elements from a first material source containing tungsten and a second material source containing the additive element X.

17. A method for manufacturing a magnetic element as described in claim 16, wherein in the step of forming the wiring layer, a first material source containing tungsten and a second material source containing the additive element X are alternately released and deposited to form a multilayer film structure in which a first layer containing tungsten and a second layer containing the additive element X are alternately laminated, and the film thickness of each of the first layer and the second layer is 1.0 nm or less.

18. A method for manufacturing a magnetic element as described in claim 17, wherein a thickness ratio of the thickness of the second layer to the sum of the thicknesses of the first layer and the second layer, i.e., thickness ratio = (thickness of the second layer) / {(thickness of the first layer) + (thickness of the second layer)}, is 0.10 or more and 0.50 or less.

19. A method for manufacturing a magnetic memory, comprising manufacturing a magnetic element according to any one of claims 12 to 18.

20. A method for producing a high frequency oscillator, comprising producing a magnetic element according to any one of claims 12 to 18.

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