JP2019047118A - Spin current magnetization reversing element, magnetoresistance effect element, magnetic memory, and magnetic device - Google Patents

Abstract

To provide a spin current magnetization reversing element, a magnetoresistance effect element, a magnetic memory, and a magnetic device that have a structure in which disconnection of a spin orbit torque wiring layer and deterioration of characteristics due to emission of heat are not easily caused.SOLUTION: A spin current magnetization reversing element 100 of the present invention includes: a spin orbit torque wiring layer 101 that extends in one direction; a first ferromagnetic layer 102 that is formed on a first surface 101a of the spin orbit torque wiring layer; and a first insulating layer 103 that is formed on a second surface 101b on a side opposite to a first ferromagnetic layer 102 side on the surface of the spin orbit torque wiring layer. The first insulating layer 103 contains boron nitride or aluminum nitride.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a spin current magnetization reversal element, a magnetoresistive effect element, a magnetic memory, and a magnetic device.

  A giant magnetoresistive (GMR) element comprising a multilayer film of a ferromagnetic layer and a nonmagnetic layer, and a tunnel magnetoresistive (TMR) element using an insulating layer (tunnel barrier layer, barrier layer) as the nonmagnetic layer are known. There is. In general, TMR elements have higher electrical resistance than GMR elements, but their magnetoresistance (MR) ratio is larger than GMR elements. Therefore, TMR elements have attracted attention as elements for magnetic sensors, high frequency components, magnetic heads, and nonvolatile random access memories (MRAMs).

  These magnetoresistive elements have a structure in which a nonmagnetic layer is sandwiched between two ferromagnetic layers different in coercive force, and the angle between the magnetization direction of one ferromagnetic layer and the magnetization direction of the other ferromagnetic layer is Accordingly, data can be read and written using the characteristic of changing the electrical resistance. As a writing method of the MRAM, writing is performed (magnetization reversal) using a magnetic field generated by a current, and writing is performed using spin transfer torque (STT) generated by flowing a current in the stacking direction of the magnetoresistive element. Methods (performing magnetization reversal) are known. Although the magnetization reversal of the TMR element using STT is efficient from the viewpoint of energy efficiency, the switching current density for causing the magnetization reversal is high. In order to improve the durability of the TMR element, the reversal current density is preferably low. The same applies to the GMR element.

  In recent years, it has been proposed that application of magnetization reversal using pure spin current generated by spin-orbit interaction is also possible (for example, Non-Patent Document 1). The spin-orbit interaction pure spin current induces spin-orbit torque (SOT) and causes magnetization reversal by SOT. The pure spin current is generated by the upward spin electrons and the downward spin electrons flowing in the same number and in the opposite direction to each other, and the charge flow associated with the pure spin current is offset. Therefore, the current flowing to the magnetoresistive element is zero, and the pure spin current does not damage the magnetoresistive element.

JP 2012-38815 A

S. Fukami, C. Zhang, S. Dutta Gupta, A. Kurenkov and H. Ohno, Nature materials (2016). DOI: 10.1038 / NMAT 4566

  The magnetoresistive effect element using SOT has a spin orbit torque wiring layer extending in one direction in order to generate a pure spin current. The spin track torque wiring layer is mainly made of heavy metal elements, but since it has a long shape, its electrical resistance is high, and the amount of heat generation accompanying the current increases. The heat generation in the spin orbit torque wiring layer may cause a break in itself, and while facilitating the magnetization reversal of the ferromagnetic layer, the nonmagnetic layer may be degraded or the wiring layer made of a low melting point metal may be used. It causes the characteristic deterioration such as dissolution or instability of magnetization of the fixed layer.

  Patent Document 1 discloses a configuration in which boron nitride known as an element having high heat dissipation is used as a side wall of a ferromagnetic layer. However, as described above, in the spin current magnetization reversal element using SOT, since the spin orbit torque wiring layer is one of the heat sources, even if the heat dissipation of the side wall of the ferromagnetic layer is enhanced, the spin orbit is It is difficult to sufficiently suppress the heat generation of the torque wiring layer.

  The present invention has been made in view of the above circumstances, and a spin current magnetization reversal element, a magnetoresistive effect element, a magnetic memory, and a magnetic device having a structure in which disconnection of the spin orbit torque wiring layer due to heat generation and characteristic deterioration do not easily occur. Intended to be provided.

  The present invention provides the following means in order to solve the above problems.

(1) A spin current magnetization reversal element according to one aspect of the present invention includes a spin orbit torque wiring layer extending in one direction, and a first ferromagnetic layer formed on the first surface of the spin orbit torque wiring layer. A first insulating layer formed on a second surface of the spin track torque wiring layer opposite to the first ferromagnetic layer, wherein the first insulating layer is boron nitride, or Contains aluminum nitride.

(2) In the spin current magnetization reversal element described in the above (1), a second insulating layer containing silicon nitride as a main component is formed on any surface other than the second surface of the spin track torque wiring layer. It may be

(3) In the spin current magnetization reversal element according to any one of the above (1) and (2), it is preferable that the first insulating layer contains silicon nitride as a main component.

(4) In the spin current magnetization reversal element according to any one of the above (1) to (3), the boron nitride or aluminum nitride forms particles, and a plurality of particles are distributed inside the first insulating film. Is preferred.

(5) In the spin current magnetization reversal element according to any one of the above (1) to (4), a surface of the spin orbit torque wiring layer opposite to the first insulating layer side and the surface It is preferable that a heat dissipation layer be formed on the surface opposite to the second insulating layer side.

(6) In the spin current magnetization reversal element according to any one of the above (1) to (5), the heat dissipation layer preferably contains a metal nitride as a main component.

(7) The magnetoresistive effect element according to an aspect of the present invention is the magnetoresistive effect element according to any one of the above (1) to (6), wherein the surface of the first ferromagnetic layer in the spin current magnetization reversal element is A nonmagnetic layer and a second ferromagnetic layer are further formed in order on the part opposite to the spin track torque wiring layer.

(8) In the magnetoresistive element described in (7) above, AB ₂ O ₄ (having MgO or a spinel structure on the surface of the second ferromagnetic layer opposite to the nonmagnetic layer side) It is preferable that a cap layer including A = Mg or Zn, B = Al, Ga, or In) be provided.

(9) In the magnetoresistive element according to any one of (7) and (8), a semiconductor element is further provided on the surface of the first insulating layer opposite to the spin track torque wiring layer side. Is preferably formed.

(10) A magnetic memory according to an aspect of the present invention includes the magnetoresistive element described in any one of the above (7) to (9).

(11) In the magnetic device according to an aspect of the present invention, the magnetic memory according to (10) is mounted on an LSI substrate as a built-in memory.

  In the present invention, a part of the surface of the spin orbit torque wiring layer constituting the spin current magnetization reversal element is covered with the first insulating layer whose heat dissipation is enhanced by containing boron nitride. Therefore, even when a large current flows in the spin track torque wiring layer, the heat generated with the current can be efficiently released to the outside through the first insulating layer. Therefore, according to the present invention, it is possible to obtain a spin current magnetization reversal element, a magnetoresistive effect element, a magnetic memory, and a magnetic device having a structure in which disconnection of the spin orbit torque wiring layer due to heat generation and characteristic deterioration do not easily occur.

FIG. 1 is a perspective view schematically showing a configuration of a spin current magnetization reversal element according to a first embodiment of the present invention. It is a schematic diagram for demonstrating the spin Hall effect. It is sectional drawing which shows typically the structure of the magnetoresistive effect element based on 1st Embodiment of this invention. (A)-(c) It is sectional drawing of a to-be-processed object in the manufacture process of the magnetoresistive effect element which concerns on 1st Embodiment of this invention. FIG. 1 is a plan view schematically showing a configuration of a magnetic memory according to a first embodiment of the present invention. It is a perspective view which shows typically the structure of the spin current magnetization inversion element which concerns on the modification 1 of 1st Embodiment of this invention.

  Hereinafter, the present invention will be described in detail with appropriate reference to the drawings. The drawings used in the following description may show enlarged features for convenience for the purpose of making the features of the present invention easier to understand, and the dimensional ratio of each component may be different from the actual one. is there. The materials, dimensions, and the like exemplified in the following description are merely examples, and the present invention is not limited to them, and can be appropriately modified and implemented within the scope of achieving the effects of the present invention. In the element of the present invention, other layers may be provided as long as the effects of the present invention are exhibited.

First Embodiment
(Spin current magnetization reversal element)
FIG. 1 is a perspective view schematically showing the configuration of a spin current magnetization reversal element 100 according to a first embodiment of the present invention. The spin current magnetization reversal element 100 includes a spin orbit torque wiring layer 101 extending in one direction D ₁ , a first ferromagnetic layer 102 formed on the first surface 101 a of the spin orbit torque wiring layer, and a spin orbit torque wiring And a first insulating layer 103 formed on the second surface 101b opposite to the first ferromagnetic layer side 102 in the surface of the layer 101.

  The spin current magnetization reversal element 100 is an element that performs magnetization reversal of a ferromagnetic layer using spin orbit torque (SOT) by pure spin current, and can be incorporated into a magnetoresistive element or the like described later. On the other hand, the spin current magnetization reversal element 100 can also be used as an assist means or main means of magnetization reversal of a ferromagnetic metal layer in a conventional magnetoresistive element using STT. The spin current magnetization reversal element 100 can also be used alone as an anisotropic magnetic sensor or an optical element utilizing a magnetic Kerr effect or a magnetic Faraday effect.

  The first ferromagnetic layer 102 is made of a known material having ferromagnetism, for example, a metal selected from the group consisting of Cr, Mn, Co, Fe, Ni, and a ferromagnetic alloy containing one or more of these metals. Become. In addition, the first ferromagnetic layer 102 is an alloy containing these metals and at least one or more elements of B, C, and N (specifically, Co-Fe or Co-Fe-B). It may consist of etc.

Also, in order to obtain higher output, it is preferable to use a Heusler alloy such as Co ₂ FeSi. The Heusler alloy comprises an intermetallic compound having a chemical composition of X ₂ YZ. X is a transition metal element or noble metal element of Co, Fe, Ni or Cu group on the periodic table, Y is a transition metal of Mn, V, Cr or Ti group or the same element as X, Z is a typical element of Group III to Group V. Examples of the Heusler alloy include Co ₂ FeSi, Co ₂ MnSi, and Co ₂ Mn _1-a Fe _a Al _b Si _1-b .

  The first ferromagnetic layer 102 preferably has an insertion layer (not shown) containing at least one of Ta, W, Mo, Cr, Ru, Rh, Ir, Pd, and Pt inside. Since the insertion layer has a function of absorbing B, diffusion of B from the first ferromagnetic layer 102 to the spin orbit torque wiring layer 101 is prevented, and the composition ratio of the spin orbit torque wiring layer 101 is disturbed. It can prevent. The insertion layer can impart perpendicular magnetic anisotropy to the first ferromagnetic layer 102 due to its interface magnetic anisotropy.

  Furthermore, the insertion layer can also be an underlayer of the first ferromagnetic layer that greatly contributes to the magnetoresistance effect. The magnetoresistive effect can be enhanced by crystal orientation of the first ferromagnetic layer 102 through the insertion layer, rather than crystal orientation from the top of the amorphized or microcrystalline spin-orbit torque wiring layer.

  The insertion layer may be located at any position in the first ferromagnetic layer 102, or may be at the interface with the spin-orbit torque wiring layer 101, and has a thickness of 0.1 nm to 2.5 nm. Is preferred.

  FIG. 2 is a schematic view for explaining the spin Hall effect generated in the spin orbit torque wiring layer 101 of FIG. 1, and is a cross-sectional view when the spin orbit torque wiring layer 101 is cut along the x direction. The mechanism by which a pure spin current is generated by the spin Hall effect will be described based on FIG.

  As shown in FIG. 2, when the current I is applied in the extending direction (-x direction) of the spin orbit torque wiring layer 101, the first spin S1 oriented in the -y direction and the second spin S2 oriented in the + y direction are , Respectively, in a direction perpendicular to the direction of the current I. The normal Hall effect and the spin Hall effect are common in that moving (moving) charges (electrons) can bend the moving (moving) direction. However, the normal Hall effect occurs only in the presence of a magnetic field, whereas the spin Hall effect causes electrons to move only by the internal field generated from the collapse of the space inversion symmetry even in the absence of a magnetic field (the current It differs greatly in the point which occurs by flowing.

  Since the number of electrons in the first spin S1 is equal to the number of electrons in the second spin S2 in a nonmagnetic material (a material that is not a ferromagnetic material), the number of electrons in the first spin S1 going upward in the figure and downward The number of electrons of the second spin S2 to be directed is equal. Thus, the current as a net flow of charge is zero. The spin current without this current is especially called pure spin current.

  When current flows in the ferromagnetic material, the first spin S1 and the second spin S2 are the same in that they are bent in opposite directions. On the other hand, it is a state in which one of the first spin S1 and the second spin S2 is more in the ferromagnetic material, and as a result, a net flow of charge is generated (a voltage is generated). Therefore, as the material of the spin orbit torque wiring layer 101, one made of only a ferromagnetic material is not used.

Here, the flow of the spins of the first spin S1 J _↑, if the flow of the spin of the second spin S2, and J _↓, spin current _{J S is} defined by _J S = _{J ↑} -J _↓. In FIG. 2, the spin current J _S flows upward in the figure as a pure spin current. Here, the spin current J _S is represented as a flow of pure spins with a polarizability of 100%.

  As shown in FIG. 1, when the ferromagnetic material (first ferromagnetic layer 102) is brought into contact with the upper surface of the spin orbit torque wiring layer 101, the pure spin current diffuses and flows into the ferromagnetic material (spin is injected ).

  Thus, the spin current magnetization reversal element 100 according to the present embodiment causes a current to flow through the spin orbit torque wiring layer 101 to generate a pure spin current, and the pure spin current is brought into contact with the spin orbit torque wiring layer 101. The diffusion in the ferromagnetic layer 102 causes the magnetization reversal of the first ferromagnetic layer 102 along with the spin orbit torque (SOT) effect due to the pure spin current.

  From the viewpoint of pure spin current generation efficiency, the material of the spin orbital torque wiring layer 101 includes a heavy metal element having an atomic number of 39 or more, which has d electrons or f electrons in the outermost shell and has large spin orbital interaction. (Alloys, intermetallic compounds, metal borides, metal carbides, metal silicides, metal phosphides, etc.) are preferable. When current is applied to a metal with a small atomic number, all internal electrons move in the opposite direction to the current regardless of the direction of each spin. On the other hand, when current is supplied to a nonmagnetic metal with a large atomic number having d electrons or f electrons in the outermost shell, the direction of movement of electrons is different due to the spin Hall effect because of the large spin-orbit interaction. Depending on the direction of spin, and a pure spin current is likely to occur.

  The first insulating layer 103 contains at least boron nitride or aluminum nitride. The first insulating layer 103 can be formed, for example, by simultaneously sputtering boron nitride or aluminum nitride and an element to be contained elsewhere by an ion beam method.

In the case where the first insulating layer 103 contains boron nitride as a main component, the insulating property is slightly low, which makes it difficult to manufacture a general semiconductor process. Boron nitride synthesized by a low temperature or vapor phase method tends to have a disordered laminated structure, and grain growth of boron nitride causes voids between grains of boron nitride, which is not sufficient insulation and Become. Also, in order to produce dense boron nitride, there is known a method of reacting boron trichloride (BCl ₃ ) and ammonia at a high temperature, etc. The cause of deterioration of the magnetic characteristics of the magnetoresistive element by this reaction It can also be In particular, in the TMR element, there is a concern that the nonmagnetic tunnel barrier layer causing the tunnel current is chemically affected to significantly deteriorate the output characteristics.

  Although it is not impossible to use the first insulating layer 103 containing boron nitride as a main component, it is not usually used because of the above-mentioned circumstances. Therefore, it is preferable that the first insulating layer 103 further contains silicon nitride as a main component. In this case, the area content of boron nitride in the first insulating layer 103 is preferably 3% or more and 30% or less. The area content of silicon nitride, which is the main component, is preferably 70% or more and 97% or less, and more preferably 75% or more and 90% or less.

  If the area content of boron nitride is too large, the insulating properties deteriorate, and the spin orbit torque wiring layer 101 can not function as an insulating layer. Therefore, it is necessary to contact the silicon nitride mainly around the boron nitride grains and maintain sufficient insulation properties. The area content of boron nitride in the first insulating layer 103 is obtained by mapping the cross section of the spin current magnetization reversal element 100 by EDS (energy dispersive X-ray analysis), and boron is contained in the first insulating layer 103. It can also be determined from the area ratio of the portion to the portion containing silicon.

  In the case where the first insulating layer 103 contains aluminum nitride as a main component, the first insulating layer 103 has good insulating properties and can be easily applied to a general semiconductor process. For example, it can be formed by film formation by reactive ion beam sputtering using nitrogen gas or metal organic chemical vapor deposition (MOCVD) using an aluminum nitride target.

  The first insulating layer 103 in the case of containing silicon nitride as a main component can be formed, for example, by simultaneously sputtering silicon nitride and boron nitride by an ion beam method.

  In the first insulating layer 103 thus formed, boron nitride or aluminum nitride forms a plurality of grains having a particle diameter of about 0.5 to 10 nm in the film of silicon nitride which is the main component, and the spin orbit torque wiring layer 101 It is distributed (dottedly) substantially uniformly in a direction substantially parallel to the interface 103a with it. In the direction substantially perpendicular to the interface 103a of the first insulating layer 103, it may be distributed at least in the vicinity (a range of about 5 nm) of the interface 103a in contact with the spin track torque wiring layer 101. It may be distributed so as to decrease continuously or intermittently.

  By containing granular boron nitride or aluminum nitride, the first insulating layer 103 can maintain adhesion with the spin track torque wiring layer 101 when heat treatment is performed, and suppress the occurrence of film peeling. Can. This is because boron nitride or aluminum nitride has a low coefficient of thermal expansion, and even if there is a temperature difference between the spin orbit torque wiring layer 101 containing the metal element and the first insulating layer 103, the adhesion between the two is large. It is because it does not change.

(Magnetoresistance effect element)
FIG. 3 is a cross-sectional view schematically showing the configuration of the magnetoresistance effect element 110 according to the present embodiment. The magnetoresistive effect element 110 has a structure in which at least the nonmagnetic layer 104 and the second ferromagnetic layer 105 are sequentially stacked on the first ferromagnetic layer 102 in the spin current magnetization reversal element 100 of FIG. Have. Hereinafter, the first ferromagnetic layer 102 will be described as a free layer capable of changing the direction of magnetization, and the second ferromagnetic layer 105 will be described as a fixed layer in which the direction of magnetization is fixed.

For the nonmagnetic layer 104, known materials can be used. For example, when the nonmagnetic layer 104 is made of an insulator, Al ₂ O ₃ , SiO ₂ , MgO, MgAl ₂ O ₄ or the like can be used as the material. In addition to these materials, materials in which a part of Al, Si, and Mg is substituted with Zn, Be, and the like can also be used. Among these, MgO and MgAl ₂ O ₄ are materials that realize coherent tunneling, so spins can be injected efficiently. When the nonmagnetic layer 104 is made of metal, Cu, Au, Ag or the like can be used as the material.

  The magnetoresistance effect element 110 corresponds to a tunneling magnetoresistance (TMR) element when the nonmagnetic layer 104 is made of an insulator, and a giant magnetoresistance (when the nonmagnetic layer 104 is made of a metal). GMR corresponds to a Giant Magnetoresistance (device) element.

  The second ferromagnetic layer 105 is made of a known material (preferably a soft magnetic material) having ferromagnetism, for example, a metal selected from the group consisting of Cr, Mn, Co, Fe, Ni, and one of these metals. It consists of a ferromagnetic alloy etc. which contain above. Also, the second ferromagnetic layer 105 is an alloy containing these metals and at least one or more elements of B, C, and N (specifically, Co-Fe or Co-Fe-B). It may consist of etc.

Also, in order to obtain higher output, it is preferable to use a Heusler alloy such as Co ₂ FeSi. The Heusler alloy comprises an intermetallic compound having a chemical composition of X ₂ YZ. X is a transition metal element or noble metal element of Co, Fe, Ni or Cu group on the periodic table, Y is a transition metal of Mn, V, Cr or Ti group or the same element as X, Z is a typical element of Group III to Group V. Examples of the Heusler alloy include Co ₂ FeSi, Co ₂ MnSi, and Co ₂ Mn _1-a Fe _a Al _b Si _1-b .

  By selecting a material having a coercive force larger than that of the first ferromagnetic layer 102 as the material of the second ferromagnetic layer 105, the magnetization of the second ferromagnetic layer 105 is reversed compared to that of the first ferromagnetic layer 102. It becomes difficult. In this case, the second ferromagnetic layer 105 can be treated as a magnetization fixed layer, and the first ferromagnetic layer 102 can be treated as a magnetization free layer.

  When the material of the second ferromagnetic layer 105 is selected to have the same coercive force as the material of the first ferromagnetic layer 102, a pinning layer is provided on the surface or in the inside of the second ferromagnetic layer 105, and The magnetization of the magnetic layer 105 is fixed. As a pinning layer, the layer of anti-ferromagnetic materials, such as IrMn and PtMn, is mentioned, for example. Since the magnetization of the second ferromagnetic layer 105 is more strongly fixed by the exchange coupling with the magnetization of the antiferromagnetic layer, also in this case, the second ferromagnetic layer 105 is the first ferromagnetic layer. As compared with 102, magnetization reversal becomes difficult.

  Furthermore, the second ferromagnetic layer 105 is preferably a laminated film containing Co and Pt when the direction of magnetization is perpendicular to the laminated surface. As a specific layer configuration, for example, [Co (0.24 nm) / Pt (0.16 nm)] 6 / Ru (0.9 nm) / [Pt (0.16 nm) / Co (0.16 nm)] 4 / Ta (0.2 nm) / FeB (1.0 nm) can be mentioned. The numerical values in parentheses indicate the film thickness.

  The second ferromagnetic layer 105 may be an in-plane magnetization film whose magnetization direction is parallel to the surface of each layer, or may be a perpendicular magnetization film perpendicular to the surface.

Of the surface of the second ferromagnetic layer 105, an oxide, for example, MgO or AB ₂ O having a spinel structure is formed on the opposite side to the nonmagnetic layer 104 (the upper side of the second ferromagnetic layer 103 in FIG. 1). It is preferable that a cap layer 106 including ₄ (A is any of Mg and Zn and B is any of Al, Ga and In) is provided.

When the second ferromagnetic layer 105 is a perpendicular magnetization film, the magnetic element in the second ferromagnetic layer 105 and the oxygen in the nonmagnetic layer 104 at the interface between the second ferromagnetic layer 105 and the nonmagnetic layer 104. Perpendicular magnetization is generated by bonding with elements. When the cap layer 106 is provided, further, at the interface between the second ferromagnetic layer 105 and the cap layer 106, the magnetic element in the second ferromagnetic layer 105 is bonded to the oxygen element in the cap layer 106. Perpendicular magnetization also occurs by doing this. That is, the cap layer 106 has a role to reinforce the magnetization in the vertical direction (stacking direction) D ₂ of the second ferromagnetic layer 105.

  Furthermore, of the surface of the cap layer 105, on the side opposite to the second ferromagnetic layer 105 (the upper side of the cap layer 106 in FIG. 1), a heavy metal element such as Ta or an element having high hardness such as TiN or TaN. The mask layer 107 may be provided. The mask layer 107 plays a role of protecting a portion left as a magnetoresistive element when etching.

  Unlike the resist which is easily scraped, the mask layer 107 can be formed thinner because it is not necessary to consider excessive scraping because the mask layer 107 is made of a heavy metal element. Therefore, even in the case where the magnetoresistive effect element is manufactured with a high degree of integration, the influence of the shadow effect by the mask layer at the time of etching can be avoided. When the degree of integration of the magnetoresistive effect elements is not increased, a resist may be used for the mask layer.

  Since the mask layer 107 made of heavy metal element easily absorbs boron, for example, when the first ferromagnetic layer 102 and the second ferromagnetic layer 105 contain boron, the boron is induced to the mask layer 107. And diffusion to other parts can be suppressed.

  The outer peripheral portions of the first ferromagnetic layer 102, the nonmagnetic layer 104, and the second ferromagnetic layer 105 may be covered with the second insulating layer 108. In that case, the second insulating layer 108 is preferably made of a film containing a nitride such as SiN, TiN, TaN, NbN, or ZrN as a main component. Here, the main component preferably means that the second insulating layer 108 contains 70% or more and 97% or less of the nitride.

  The oxide in the cap layer 106 tends to be in the state of being deficient in oxygen by the annealing treatment, and tends to deprive oxygen from the surrounding film if it contains oxygen so as to compensate for the deficient portion. As a result, the electrical conductivity of the film deprived of oxygen is increased, and the electrical characteristics deviate from the design values. However, in the present embodiment, since the second insulating layer 108 covering the outer peripheral portion of the cap layer 106 is formed of a film containing nitride as a main component, such a problem can be avoided.

(Manufacturing method of magnetoresistance effect element)
An example of the manufacturing method of the magnetoresistive effect element 110 is demonstrated using FIG.4 (a)-(c).

  First, as shown in FIG. 4A, a known film forming method such as a physical vapor deposition (PVD) method or a chemical vapor deposition (CVD) method is used on the one surface 10a of the base material 10, Films 103A, 101A, 102A, 104A, 105A, 106A, which constitute the first insulating layer, spin track torque wiring layer, first ferromagnetic layer, nonmagnetic layer, second ferromagnetic layer, cap layer, and mask layer 107A are formed in order. Examples of physical vapor deposition include resistance heating evaporation, electron beam evaporation, molecular beam epitaxy (MBE), ion plating, ion beam deposition, and sputtering. Examples of the chemical vapor deposition include thermal CVD, photo CVD, plasma CVD, metal organic chemical vapor deposition (MOCVD), atomic layer deposition (ALD) and the like. When the magnetoresistive effect element 110 is formed on a semiconductor element having a predetermined function, the semiconductor element plays a role of the substrate 10.

  In the case where the functional part configured of the first ferromagnetic layer, the nonmagnetic layer, and the second ferromagnetic layer is a TMR element, the nonmagnetic layer is a tunnel barrier layer. The tunnel barrier layer is formed, for example, by the following procedure. First, sputtering is performed on the first ferromagnetic layer to form a metal thin film composed of about 0.4 to 2.0 nm of magnesium, aluminum and divalent cations of a plurality of nonmagnetic elements. Subsequently, natural oxidation is performed by plasma oxidation or oxygen introduction, and a heat treatment is performed thereafter to obtain a tunnel barrier layer.

  Since the layer formed by reactive sputtering is amorphous and needs to be crystallized, it is preferable to anneal the obtained functional part.

  The functional portion obtained by the annealing treatment has an improved magnetoresistance ratio as compared with the functional portion obtained without the annealing treatment. It is considered that this is because the annealing process improves the uniformity and the orientation of the crystal size of the nonmagnetic layer (tunnel barrier layer).

  As annealing treatment, after heating for 5 minutes or more and 100 minutes or less in a temperature range of 300 ° C. or more and 500 ° C. or less in an inert atmosphere such as Ar, 100 ° C. with a magnetic field of 2 kOe or more and 10 kOe or less applied. It is preferable to heat at a temperature of at least 500 ° C. for a time of at least 1 hour and at most 10 hours.

  Next, as shown in FIG. 4B, the five formed films 102A, 104A, 105A, 106A, and 107A are not required to be used by photolithography, ion milling, reactive ion etching (RIE) or the like. It is processed so that it will become a desired shape by removing a portion.

  Next, as shown in FIG. 4C, the spin track torque wiring layer 101, the first ferromagnetic layer 102, the nonmagnetic layer 104, the second ferromagnetic layer 105, the cap layer 106, and the mask are formed using the CVD method. A second insulating layer 108 containing silicon nitride as a main component is formed to cover the exposed portion of the layer 107. By this process, a second insulating layer containing silicon nitride as a main component is formed on any surface of the spin track torque wiring layer other than the second surface.

  Further, the outermost surface of the formed second insulating layer 108 is planarized by CMP. This CMP process may be performed until the outermost surface of the second insulating layer 108 is exposed until the mask layer 107 is exposed (up to the position of the broken line in FIG. 4C), but the silicon nitride film remains on the mask layer 107 You may stop in the state.

  The magnetoresistive effect element 110 of the present embodiment can be obtained through the steps described above. The base material 10 used here may be removed or may be left depending on the application of the magnetoresistive effect element 110.

(Magnetic memory)
The magnetoresistive effect element 110 reads and writes data using the characteristic that the element resistance changes in accordance with the angle between the magnetization direction of the first ferromagnetic layer 102 and the magnetization direction of the second ferromagnetic layer 105. Can be operated as In this case, the semiconductor element that performs operations of the magnetic memory and its peripheral circuits is formed on the first insulating layer 103 side (under the first insulating layer 103 in FIG. 3) from the viewpoint of increasing the degree of integration. Is preferred.

  As shown in FIG. 5, in the magnetic memory 120, one wiring layer of each magnetoresistance effect element 110 is connected by source lines (bit lines) SL1, SL2, SL3, ..., and the other wiring layers are connected to each other. The word lines WL1, WL2, WL3,... Are connected. By mounting a plurality of such magnetic memories as a built-in memory on an LSI substrate, it is possible to obtain a magnetic device in which the influence of the delay proportional to the distance between the magnetoresistive elements 110 is reduced.

  As described above, in the present embodiment, a portion of the surface of the spin track torque wiring layer constituting the spin current magnetization reversal element is covered with the first insulating film whose heat dissipation is enhanced by containing boron nitride. There is. Therefore, even when a large current flows in the spin track torque wiring layer, the heat generated with the current can be efficiently released to the outside through the first insulating film. Therefore, according to the present embodiment, it is possible to obtain a spin current magnetization reversal element, a magnetoresistive effect element, a magnetic memory, and a magnetic device having a structure in which characteristic degradation due to heat generation hardly occurs.

(Modification 1)
FIG. 6 is a perspective view schematically showing the configuration of the spin current magnetization reversal element 130 according to the first modification of the present embodiment.

In the spin current magnetization reversal element 100 of the present embodiment described above, the heat conductivity of the second insulating layer 108 is limited to that due to lattice vibration, so the heat dissipation of the second insulating layer 108 itself is low. On the other hand, in the spin current magnetization reversal element 130 of the first modification, the second insulating layer 138 is thinly formed in a range in which the insulation can be maintained, and the heat dissipation is further made of a metallic material such as metal nitride. The layer 139 is formed and has a structure with high heat dissipation.
In the heat dissipation layer 139 containing metal nitride as a main component, the area content of the metal nitride is preferably 70% or more and 100% or less, and more preferably 75 or more and 97 or less. Specifically, silicon nitride, aluminum nitride, or the like can be used as the metal nitride.

  There is no limitation on the shape, size, and the like of the heat dissipation layer 139, but from the viewpoint of increasing the amount of heat dissipation, the larger the area covered by the second insulating layer 138, the better. The configuration other than the heat dissipation layer 139 is similar to that of the spin current magnetization reversal element 100.

100, 130 · · · spin current magnetization reversal element 101, 131 · · · spin track torque wiring layer 101a, 131a · · · first surface 101b, 131b · · · second surface 102, 132 · · · first ferromagnetic Layers 103, 133: first insulating layers 103a, 133a: interfaces 104, 134: nonmagnetic layers 105, 135: second ferromagnetic layers 106, 136: cap layers 107, 137 ... Mask layer 108, 138 Second insulating layer 110 Magnetoresistance effect element 120 Magnetic memory 139 Heat dissipation layer D ₁ Extension direction D ₂ Layering direction

Claims (11)

A spin track torque wiring layer extending in one direction;
A first ferromagnetic layer formed on the first surface of the spin track torque wiring layer;
And a first insulating layer formed on a second surface of the spin track torque wiring layer opposite to the first ferromagnetic layer.
The spin current magnetization reversal element, wherein the first insulating layer contains boron nitride or aluminum nitride.   2. The spin current magnetization reversal according to claim 1, wherein a second insulating layer containing silicon nitride as a main component is formed on any surface other than the second surface of the spin track torque wiring layer. element.   The spin current magnetization reversal element according to claim 1, wherein the first insulating layer contains silicon nitride as a main component.   The spin current magnetization reversal element according to any one of claims 1 to 3, wherein the boron nitride or the aluminum nitride forms particles, and a plurality of particles are distributed inside the first insulating film.   A heat dissipation layer is formed on the surface opposite to the first insulating layer side and the surface opposite to the second insulating layer side among the surfaces of the spin track torque wiring layer. The spin current magnetization reversal element according to any one of 1 to 4.   The spin current magnetization reversal element according to any one of claims 1 to 5, wherein the heat dissipation layer contains a metal nitride as a main component.   A nonmagnetic layer, a surface of the first ferromagnetic layer in the spin current magnetization reversal element according to any one of claims 1 to 6, further on a portion opposite to the spin orbit torque wiring layer, 2. A magnetoresistive element characterized in that two ferromagnetic layers are formed in order. Of the surface of the second ferromagnetic layer, AB ₂ O ₄ (A = Mg or Zn, B = Al, Ga or In) having MgO or a spinel structure on the surface opposite to the nonmagnetic layer side The magnetoresistive effect element according to claim 7, further comprising: a cap layer.   9. The magnetic resistance according to claim 7, wherein a semiconductor element is further formed on a surface of the first insulating layer opposite to the spin track torque wiring layer side. Effect element.   A magnetic memory comprising the magnetoresistive element according to any one of claims 7 to 9.   A magnetic device characterized in that the magnetic memory according to claim 10 is mounted on an LSI substrate as a built-in memory.

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