JP2009283661A - Magnetoresistive effect element, magnetic head, magnetic storage device, and magnetic memory device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure can prevent diffusion of an element such as Ge in a reference layer while keeping exchange coupling between the reference layer and other layer, in a spin valve film of a CPP magnetoresistive effect element. <P>SOLUTION: A diffusion prevention layer formed of an Al thin film is formed on at least either of a lower part and an upper part of the reference layer included in a spin valve layer of the CPP magnetoresistive effect element. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetoresistive effect element, a magnetic head, a magnetic storage device, and a magnetic memory device. The present invention also relates to a CPP type magnetoresistive element, a magnetic head using the same magnetoresistive element, and a magnetic storage device using the same magnetic head. The present invention further relates to a magnetic memory device using the magnetoresistive effect element.

  In recent years, a magnetoresistive element is used as a reproducing element for reproducing information recorded on a magnetic recording medium in a magnetic head of a magnetic storage device. The magnetoresistive effect element reproduces information recorded on the magnetic recording medium using a magnetoresistive effect that converts a change in the direction of the signal magnetic field leaking from the magnetic recording medium into a change in electrical resistance.

  With the increase in recording density of magnetic storage devices, those equipped with magnetoresistive effect elements having a spin valve film have become mainstream. In this spin valve film, a fixed magnetic layer whose magnetization is fixed in a predetermined direction, a nonmagnetic layer, and a free magnetic layer whose magnetization direction changes according to the direction and strength of the leakage magnetic field from the magnetic recording medium are laminated. is doing. In the spin valve film, the electric resistance value changes according to the angle formed by the magnetization of the fixed magnetization layer and the magnetization of the free magnetization layer. This change in electrical resistance value is detected as a voltage change by passing a constant sense current through the spin valve film. In this way, the bits recorded on the magnetic recording medium by the magnetoresistive effect element are reproduced.

  Conventionally, as a magnetoresistive effect element, a CIP (Current-In-Plane) type structure in which a sense current flows in the in-plane direction of the spin valve film has been adopted. Here, in order to further increase the recording density of the magnetic recording apparatus, it is necessary to increase the linear recording density and the track density on the magnetic recording medium. On the other hand, in the magnetoresistive effect element, it is necessary to reduce both the element width corresponding to the track width of the magnetic recording medium and the element height (element depth), that is, the element cross-sectional area. In this case, since the current density of the sense current is increased in the CIP type structure, there is a possibility that performance degradation may occur due to migration of a material constituting the spin valve film due to overheating.

  Therefore, a CPP (Current-Perpendicular-to-Plane, hereinafter the same) type structure in which a sense current flows in the stacking direction of the spin valve film, that is, the direction in which the fixed magnetic layer, the nonmagnetic layer, and the free magnetic layer are stacked. Things have been proposed. Since the CPP type spin valve film has a feature that the output hardly changes even when the element width is narrowed, it is suitable for increasing the recording density of the magnetic recording apparatus.

  The output of the CPP type spin valve film is determined by the amount of change in magnetoresistance when the external magnetic field applied to the spin valve film is swept from one direction to the opposite direction. This magnetoresistance change amount is the magnetoresistance change amount per unit area of the film surface perpendicular to the direction of the sense current. The magnetoresistance change amount per unit area is obtained by multiplying the magnetoresistance change amount of the spin valve film and the area of the film surface of the spin valve film. In order to increase the amount of change in magnetoresistance per unit area, it is necessary to use a material having a large product of the spin-dependent bulk scattering coefficient and the specific resistance for the free magnetic layer and the fixed magnetic layer. The spin-dependent bulk scattering coefficient indicates the degree to which conduction electrons are scattered in the free magnetic layer or the fixed magnetic layer depending on the spin direction of the conduction electrons. The greater the spin-dependent bulk scattering coefficient, the greater the magnetoresistance change.

As a material having a large spin-dependent bulk scattering coefficient, a magnetoresistive element using a soft magnetic alloy having a Heusler alloy composition for a free magnetic layer has been proposed.
JP-A-9-199768 Japanese Patent No. 3470952 JP-A-2005-116703 JP 2007-180470 A

  An object of the present invention is to provide a structure capable of preventing diffusion of elements such as Ge in a reference layer while maintaining exchange coupling between the reference layer and another layer in a spin valve film of a CPP type magnetoresistive effect element. To do.

  A diffusion prevention layer having a thin film of Al (aluminum is shown; the same applies hereinafter) is formed at the interface of the reference layer included in the spin valve layer of the CPP type magnetoresistive element.

  The diffusion preventing layer prevents diffusion of elements such as Ge in the reference layer. Even if the diffusion preventing layer is formed, exchange coupling between the reference layer and another layer via the diffusion preventing layer is maintained.

  It is possible to prevent diffusion of elements such as Ge in the reference layer while maintaining exchange coupling between the reference layer and other layers in the spin valve film, so that the magnetic field is detected with high reliability. A magnetoresistive element having good sensitivity and high output can be provided.

  The embodiment includes a magnetoresistive element, a magnetic head, a magnetic storage device, and a magnetic memory device for reproducing information in the magnetic storage device, as will be described later. Here, the magnetoresistive effect element has a CPP type structure in which a sense current flows in the stacking direction of the stacked films constituting the magnetoresistive effect element.

  This magnetoresistive effect element reproduces information recorded on the magnetic recording medium by utilizing a magnetoresistive effect that converts a change in the direction of the signal magnetic field leaking from the magnetic recording medium into a change in electrical resistance. The magnetoresistive element includes a spin valve film that can increase the recording density of the magnetic storage device. In a spin valve film, a fixed magnetization layer whose magnetization is fixed in a predetermined direction, a nonmagnetic layer, and a free magnetization layer whose magnetization direction changes according to the direction and strength of the leakage magnetic field from the magnetic recording medium are laminated. ing. In the spin valve film, the electric resistance value changes according to the angle formed by the magnetization of the fixed magnetization layer and the magnetization of the free magnetization layer. By detecting this change in electrical resistance value as a voltage change by passing a constant sense current through the spin valve film, it is possible to reproduce the bits recorded on the magnetic recording medium.

  That is, the embodiment is a CPP type magnetoresistive element having upper and lower electrode terminals for passing a sense current in a direction perpendicular to the film surface of the laminated film constituting the element. The magnetoresistive effect element has a magnetoresistive effect film. In the magnetoresistive film, an antiferromagnetic layer, a pinned layer, a nonmagnetic coupling layer, a reference layer, a nonmagnetic intermediate layer, and a free magnetic layer whose magnetization rotates according to an external magnetic field are stacked at least from below. That is, the magnetoresistive effect element has a spin valve structure. Further, a magnetic material containing Ge, Si, or Mn is used as the reference layer. Further, a diffusion preventing layer made of Al having an ultrathin structure is inserted between each of the nonmagnetic coupling layer and the nonmagnetic intermediate layer and the reference layer.

The composition of the material of the reference layer is (Co _x Fe _100-x ) M _y (where 0 ≦ x ≦ 100, 0 <y <30 atomic%, and M is Ge, Si or Mn) Also good. Alternatively, the composition of the reference layer may be (Co _x Mn _100-x ) M _y (where 0 ≦ x ≦ 100, 0 <y <30 atomic%, and M is Ge, Si, or Al). Alternatively, the composition of the reference layer is Co ₅₀ Fe ₂₅ Al _12.5 Si _12.5 , Co ₅₀ Fe ₂₅ Ge _12.5 Si _12.5 , Co ₅₀ Fe ₂₅ Ge _12.5 Al _12.5 , Co ₅₀ Fe ₂₅ Ge _12.5 Mn _12.5 , Co ₅₀ Fe ₂₅ Al _12.5 Mn _It may be _12.5 or Co ₅₀ Fe ₂₅ Si _12.5 Mn _12.5 .

  The film thickness of the diffusion prevention layer made of Al is preferably in the range of 0.1 to 1.0 [nm].

  Another embodiment is a CPP type magnetoresistive element having upper and lower electrode terminals for passing a sense current in a direction perpendicular to the film surface of the laminated film constituting the element. The magnetoresistive effect element has a magnetoresistive effect film. In this embodiment, the magnetoresistive film has the following laminated structure. That is, a lower antiferromagnetic layer, a lower pinned layer, a lower nonmagnetic coupling layer, a lower reference layer, and a lower nonmagnetic intermediate layer are stacked from the bottom. Furthermore, a free magnetic layer whose magnetization rotates according to an external magnetic field is laminated. Further, an upper nonmagnetic intermediate layer, an upper reference layer, an upper nonmagnetic coupling layer, an upper pinned layer, and an upper antiferromagnetic layer are laminated. That is, the magnetoresistive film has a so-called dual type spin valve structure. A magnetic material containing highly diffused Ge, Si, or Mn is used for the upper and lower reference layers. Between each of the upper nonmagnetic coupling layer and the upper nonmagnetic intermediate layer and the upper reference layer, a diffusion prevention layer made of Al having an ultrathin structure is inserted. Similarly, an anti-diffusion layer made of Al having an ultrathin structure is inserted between each of the lower magnetic coupling layer and the lower nonmagnetic intermediate layer and the lower reference layer. The diffusion prevention layer formed of these Al prevents the diffusion of each material, and the reproduction output, reliability, and sensitivity of the magnetic storage device or magnetic memory device using the magnetoresistive effect element are improved.

  Still another embodiment is a CPP type magnetoresistive element having upper and lower electrode terminals for passing a sense current in a direction perpendicular to the film surface of the laminated film constituting the element. The magnetoresistive effect element has a magnetoresistive effect film. In this embodiment, the magnetoresistive film has the following laminated structure. That is, an antiferromagnetic layer, a pinned layer, a nonmagnetic coupling layer, a reference layer, an oxide layer, and a free magnetic layer whose magnetization rotates according to an external magnetic field are stacked at least from the bottom. This magnetoresistive film has a so-called spin valve structure. The reference layer uses a magnetic material containing Ge, Si, or Mn having a large diffusion, and is formed of Al having a very thin structure between the nonmagnetic coupling layer and the oxide layer and the reference layer. Insert a layer. These diffusion prevention layers formed of Al prevent the diffusion of each material, thereby improving the reproduction output, reliability, and sensitivity of the magnetic storage device or magnetic memory device using the magnetoresistive effect element.

  Still another embodiment is a magnetic head including the magnetoresistive element of any of the above embodiments.

  Still another embodiment is a magnetic storage device having a magnetic head including the magnetoresistive element and a magnetic recording medium on which information is recorded or information is read by the magnetic head.

  Yet another embodiment is a magnetic memory device having the magnetoresistive effect element according to any of the above embodiments.

  Here, when the magnetic layer containing Si, Ge or Mn is used as the reference layer as described above, the reproduction output, reliability, and sensitivity of the magnetoresistive effect film necessary for practical use are secured by diffusion of these elements. It was difficult to do. The magnetoresistive effect element of each of the above embodiments can prevent deterioration of characteristics due to these easily diffusing materials.

  That is, in each of the above embodiments, by providing a diffusion prevention layer made of Al, diffusion of each material can be prevented, and reproduction output, reliability, and sensitivity can be improved. Here, the diffusion of Si, Ge or Mn contained in the magnetic layer into the non-magnetic coupling layer is controlled by setting the film thickness of the diffusion prevention layer formed of Al as described above in the range of 0.1 to 1.0 nm. And the binding force between the pinned layer and the reference layer increases. Similarly, by inserting a diffusion prevention layer formed of Al between the nonmagnetic intermediate layer and the reference layer, deterioration of roughness due to diffusion of Si, Ge, or Mn atoms can be suppressed. As a result, the sensitivity of the free magnetic layer can be improved, and as a result, the reproduction output can be increased.

  Here, when the film thickness of the diffusion prevention layer made of Al is thicker than 1 nm, the exchange coupling between the pinned layer and the reference layer by the nonmagnetic coupling layer disappears. For this reason, the optimum range of the film thickness of the diffusion prevention layer formed of Al is from 0.1 nm to 1 nm that can be formed by sputtering.

  In addition, the magnetic head according to the above embodiment includes the magnetoresistive effect element in which the diffusion prevention layer formed of ultrathin Al is inserted at both interfaces of the reference layer. Since the magnetoresistive effect element according to the embodiment has high reliability, high sensitivity, and high output, the magnetic head has a configuration that can cope with magnetic recording with higher recording density.

  As another embodiment, a magnetic storage device including a magnetic head having any one of the above magnetoresistive elements and a magnetic recording medium can be considered. According to the magnetic recording apparatus, as described above, since the magnetoresistive effect element has a high output, the recording density of the magnetic storage apparatus can be increased.

As yet another embodiment, a magnetic memory using a CPP type magnetoresistive element having an antiferromagnetic layer, a pinned layer, a nonmagnetic coupling layer, a reference layer, a nonmagnetic intermediate layer, and a free magnetic layer as described above. A device is conceivable. Here, the reference layer has a large spin-dependent bulk scattering (Co _x Fe _100-x ) M _y (where 0 ≦ x ≦ 100, 0 <y <30 atomic%, and M is Ge, Si, or Mn. ). Alternatively, the reference layer has (Co _x Mn _100-X ) M _y (where 0 ≦ x ≦ 100, 0 <y <30 atomic%, and M is Ge, Si, or Al). Alternatively, the reference layer may be Co ₅₀ Fe ₂₅ Al _12.5 Si _12.5 , Co ₅₀ Fe ₂₅ Ge _12.5 Si _12.5 , Co ₅₀ Fe ₂₅ Ge _12.5 Al _12.5 , Co ₅₀ Fe ₂₅ Ge _12.5 Mn _12.5 , Co ₅₀ Fe ₂₅ Al _12.5 Mn _12.5 , or with a _{Co 50 Fe 25 Si 12.5 Mn 12.5} . Further, a diffusion prevention layer made of ultrathin Al is inserted between each of the nonmagnetic coupling layer and the nonmagnetic intermediate layer and the reference layer. As a result, the diffusion of each material can be prevented and the reproduction output, reliability, and sensitivity can be improved. Writing means is provided for applying a magnetic field to the magnetoresistive effect film having such a configuration to direct the magnetization of the free magnetic layer in a predetermined direction. Also provided is a reading means for detecting a resistance value by supplying a sense current to the magnetoresistive film. In this way, a magnetic memory device is obtained.

  According to each of the above embodiments, it is possible to provide a magnetoresistive effect element having high reliability, good sensitivity for detecting a magnetic field, and high output, and a magnetic head, a magnetic storage device, and a magnetic memory device using the magnetoresistive effect element. it can.

  Hereinafter, Example 1 will be described in detail with reference to the drawings. For convenience of explanation, unless otherwise specified, “magnetic resistance change amount ΔRA per unit area” is abbreviated as “magnetic resistance change amount ΔRA” or simply “ΔRA”.

A composite magnetic head provided with the magnetoresistive effect element of Example 1 and an inductive recording element will be described. FIG. 1 is a diagram showing the main part of the medium facing surface of a composite magnetic head. In FIG. 1, the direction of the arrow X indicates the moving direction of a magnetic recording medium (not shown) facing the magnetoresistive element. Referring to FIG. 1, a composite magnetic head 10 is roughly composed of a magnetoresistive effect element 20 formed on a flat ceramic substrate 11 such as Al ₂ O ₃ —TiC serving as a base of a head slider, It has an inductive recording element 13 formed thereon.

The inductive recording element 13 includes an upper magnetic pole 14 having a width corresponding to the track width of the magnetic recording medium on the medium facing surface, and a lower magnetic pole 16 facing the upper magnetic pole 14 with a recording gap layer 15 made of a nonmagnetic material interposed therebetween. Have The inductive recording element 13 further includes a yoke (not shown) that magnetically connects the upper magnetic pole 14 and the lower magnetic pole 16, and a coil (not shown) that is wound around the yoke and generates a recording magnetic field by a recording current. ). The upper magnetic pole 14, the lower magnetic pole 16, and the yoke are made of a soft magnetic material. Examples of the soft magnetic material include a material having a high saturation magnetic flux density in order to secure a recording magnetic field, such as Ni ₈₀ Fe ₂₀ , CoZrNb, FeN, FeSiN, FeCo, or CoNiFe. The configuration of the inductive recording element 13 is not limited to the above, and other known configurations can be used.

  The magnetoresistive effect element 20 includes a lower electrode 21, a magnetoresistive effect film 30 (hereinafter referred to as “GMR film 30”), an alumina film 25, an upper electrode on an alumina film 12 formed on the surface of the ceramic substrate 11. 22 has a laminated structure. The GMR film 30 is electrically connected to the lower electrode 21 and the upper electrode 22, respectively.

  A magnetic domain control film 24 is provided on both sides of the GMR film 30 via an insulating film 23. The magnetic domain control film 24 has, for example, a stacked structure of a Cr film and a ferromagnetic CoCrPt film. The magnetic domain control film 24 makes the free magnetic layer (shown in FIG. 2) included in the GMR film 30 a single magnetic domain and prevents the occurrence of Barkhausen noise. The lower electrode 21 and the upper electrode 22 have a function as a magnetic shield in addition to a function as a flow path of the sense current Is. Therefore, the lower electrode 21 and the upper electrode 22 are formed of a soft magnetic alloy such as NiFe or CoFe. Further, a conductive film such as a Cu film, a Ta film, or a Ti film may be provided at the interface between the lower electrode 21 and the GMR film 30. The magnetoresistive effect element 20 and the inductive recording element 13 are preferably covered with an alumina film, a hydrogenated carbon film, or the like in order to prevent corrosion or the like.

  The sense current Is flows, for example, from the upper electrode 22 through the GMR film 30 perpendicularly to the film surface and reaches the lower electrode 21. The electric resistance value of the GMR film 30, that is, the so-called magnetoresistance value changes in accordance with the intensity and direction of the signal magnetic field leaking from the magnetic recording medium. In the magnetoresistive effect element 20, a change in the magnetoresistance value of the GMR film 30 can be detected as a voltage change by passing a sense current Is of a predetermined current amount. In this manner, information recorded on the magnetic recording medium can be reproduced using the magnetoresistive effect element 20. The direction in which the sense current Is flows is not limited to the direction shown in FIG. In addition, the moving direction of the magnetic recording medium may be a direction opposite to the X direction.

  FIG. 2 is a cross-sectional view of the first example GMR film included in the magnetoresistive effect element of the first embodiment.

  Referring to FIG. 2, in the GMR film 30 of the first example, a base layer 31, an antiferromagnetic layer 32, a fixed magnetization stack 33, a nonmagnetic metal layer 37, a free magnetization layer 38, and a protective layer 39 are sequentially stacked. ing. The GMR film 30 has a so-called single spin valve structure. The underlayer 31 is formed on the surface of the lower electrode 21 shown in FIG. 1 by sputtering or the like. For example, a stacked body of a NiCr film, a Ta film (for example, a film thickness of 5 nm), and a NiFe film (for example, a film thickness of 5 nm). Etc. This NiFe film preferably has a Fe content in the range of 17 atomic% to 25 atomic%. By using the NiFe film having such a composition, the antiferromagnetic layer 32 is epitaxially grown on the surface of the (111) crystal plane which is the crystal growth direction of the NiFe film and the crystallographically equivalent crystal plane. Thereby, the crystallinity of the antiferromagnetic layer 32 can be improved.

  The antiferromagnetic layer 32 is formed of, for example, a Mn-TM alloy (TM includes at least one of Pt, Pd, Ni, Ir, and Rh) having a film thickness of 4 nm to 30 nm (preferably 4 nm to 10 nm). The Examples of the Mn-TM alloy include PtMn, PdMn, NiMn, IrMn, and PtPdMn. The antiferromagnetic layer 32 causes exchange interaction with the first pinned magnetic layer (that is, the pinned layer) 34 of the pinned magnetization stack 33 to pin the magnetization of the pinned layer 34 in a predetermined direction. The fixed magnetization stack 33 has a so-called stacked ferrimagnetic structure in which a pinned layer 34, a nonmagnetic coupling layer 35, and a reference layer 36 are stacked in this order from the antiferromagnetic layer 32 side. In the fixed magnetization stack 33, the magnetization of the pinned layer 34 and the magnetization of the reference 36 are antiferromagnetically exchange-coupled, and the magnetization directions are antiparallel to each other.

As a soft magnetic material suitable for the pinned layer 34, Co ₆₀ Fe ₄₀ or NiFe can be cited because of its low specific resistance. Here, since the magnetization of the pinned layer 34 is opposite to the magnetization direction of the reference layer 36, the pinned layer 34 acts to reduce the magnetoresistance change ΔRA. In such a case, the use of a ferromagnetic material having a low specific resistance as the pinned layer 34 can suppress a decrease in the magnetoresistance change ΔRA.

The reference layer 36 is formed of a ferromagnetic material containing at least one of Co, Ni, and Fe having a thickness of 1 to 10 nm. The composition of the reference 36 may be CoFe, CoFeB, CoFeAl, NiFe, FeCoCu, or CoNiFe. Alternatively, (CoxFe _100-X ) M _y (where 0 ≦ x ≦ ₁₀₀ , 0 <y <30 atomic%, M represents Ge, Si, or Mn) may be used. Alternatively, (Co _x Mn _100-x ) M _y (where 0 ≦ x ≦ 100, 0 <y <30 atomic%, M represents Ge, Si, or Al) may be used. Or Co ₅₀ Fe ₂₅ Al _12.5 Si _12.5 , Co ₅₀ Fe ₂₅ Ge _12.5 Si _12.5 , Co ₅₀ Fe ₂₅ Ge _12.5 Al _12.5 , Co ₅₀ Fe ₂₅ Ge _12.5 Mn _12.5 , Co ₅₀ Fe ₂₅ Al _12.5 Mn _12.5 , or Co ₅₀ Fe ₂₅ Si _12.5 Mn _12.5 or the like may be used. Note that each of the pinned layer 34 and the reference layer 36 may have a single-layer configuration or a stacked-layer configuration of two or more layers. In the case of a structure of a stacked body, materials having different composition ratios may be used for each layer included in the stacked body in the same combination of elements. Alternatively, a material in which different elements are combined may be used for each layer. Particularly preferable as the material of the reference layer 36 is (Co _x Fe _100-X ) M _y (where 0 ≦ x ≦ 100, 0 <y <30 atomic%, M represents Ge, Si or Mn). . Or a _{(Co x Mn 100-x)} M y (0 ≦ x ≦ 100,0 <y <30 at%, where, M denotes the Ge, Si or Al). Or Co ₅₀ Fe ₂₅ Al _12.5 Si _12.5 , Co ₅₀ Fe ₂₅ Ge _12.5 Si _12.5 , Co ₅₀ Fe ₂₅ Ge _12.5 Al _12.5 , Co ₅₀ Fe ₂₅ Ge _12.5 Mn _12.5 , Co ₅₀ Fe ₂₅ Al _12.5 Mn _12.5 or Co ₅₀ Fe ₂₅ Si _12.5 Mn _12.5 . This is due to the following reason. The spin-dependent bulk scattering coefficient of each of the above materials is comparable to the spin-dependent bulk scattering coefficient of CoFe, which is a soft magnetic material, and is relatively larger than other soft magnetic materials. For example, the spin-dependent bulk scattering coefficient of Co ₉₀ Fe ₁₀ is 0.55, whereas the spin-dependent bulk scattering coefficient of Co ₅₀ Fe ₂₅ Ge ₂₅ is 0.50. In terms of specific resistance, CoFeGe is much larger than CoFe, for example, Co ₉₀ Fe ₁₀ is 20 μΩcm, whereas Co ₅₀ Fe ₂₅ Ge ₂₅ is 130 μΩcm, which is 6 times or more. The amount of change in magnetoresistance depends on the product of the spin-dependent bulk scattering coefficient and the specific resistance. For this reason, CoFeGe and the like have a much larger magnetoresistance change ΔRA than CoFe. Therefore, the magnetoresistance change ΔRA can be significantly increased by using any of these materials for the reference layer 36.

  In addition, Al thin films, that is, diffusion preventing layers 1-1 and 1-2 made of Al, are inserted at the interface between the nonmagnetic layers 35 and 37 and the material of the reference layer 36. Alternatively, when the reference layer 36 has a layered structure as described above, an Al thin film, that is, a diffusion prevention layer formed of Al, is formed at the interface between each of the nonmagnetic layers 35 and 37 and the layered magnetic layer. 1-1 and 1-2 are inserted. In this case, the Mn, Si, and Ge materials effective in increasing the specific resistance are prevented from diffusing into the nonmagnetic layers 35 and 37. At this time, the film thickness of the diffusion preventing layers 1-1 and 1-2 formed of Al is preferably in the range of 0.1 nm to 1 nm which is a film thickness that can be sputtered as a film. The film thickness of the nonmagnetic coupling layer 35 is set in a range in which the first pinned magnetic layer (that is, the pinned layer) 34 and the second pinned magnetic layer (that is, the reference layer) 36 are antiferromagnetically exchange coupled. The range is 0.4 nm to 1.5 nm (preferably 0.4 nm to 0.9 nm). The nonmagnetic coupling layer 35 is formed of a nonmagnetic material such as Ru, Rh, Ir, Ru-based alloy, Rh-based alloy, or Ir-based alloy. As the Ru-based alloy, an alloy of Ru and any one of Co, Cr, Fe, Ni, and Mn is preferable. Alternatively, as this Ru-based alloy, an alloy of Ru and any two or more of Co, Cr, Fe, Ni, and Mn is also suitable.

  The nonmagnetic intermediate layer 37 is formed of, for example, a nonmagnetic conductive material having a thickness of 1.5 nm to 10 nm. Examples of the conductive material suitable for the nonmagnetic intermediate layer 37 include Cu, Al, and Cr.

  The free magnetic layer 38 is provided on the surface of the nonmagnetic intermediate layer 37 and is made of, for example, CoFe, NiFe, CoFeAl, or CoFeGe having a thickness of 2 nm to 12 nm.

  The protective layer 39 is formed of a nonmagnetic conductive material, for example, formed of a metal film containing any of Ru, Cu, Ta, Au, Al, and W, or formed of a laminate of these metal films. Is done. The protective layer 39 prevents the free magnetic layer 38 from being oxidized during the heat treatment for causing the antiferromagnetism of the antiferromagnetic layer 32 described below to appear.

  Next, a method for forming the GMR film 30 of the first example will be described with reference to FIG. First, each layer from the base layer 31 to the protective layer 39 is formed using the above-described materials by sputtering, vapor deposition, CVD, or the like.

  Next, the laminated body thus obtained is heat-treated in a magnetic field. Specifically, in a vacuum atmosphere, for example, the heating temperature is 250 ° C. to 320 ° C., the heating time is about 2 to 4 hours, and the applied magnetic field is set to 1592 kA / m. By this heat treatment, a part of the Mn-TM alloy described above becomes a regular alloy, and antiferromagnetism appears there. In addition, by applying a magnetic field in a predetermined direction during the heat treatment, the magnetization direction of the antiferromagnetic layer 32 is set to a predetermined direction, and the pinned layer 33 is pinned by the exchange interaction between the antiferromagnetic layer 32 and the pinned layer 33. The magnetization of the layer 33 can be fixed in a predetermined direction.

  Next, the GMR film 30 is obtained by patterning the stacked body from the base layer 31 to the protective layer 39 into a predetermined shape. Note that the GMR films of the second to third examples described below can also be formed by the same method as the GMR film 30 of the first example.

  Next, a second example GMR film as a GMR film included in the magnetoresistive effect element 20 of Example 1 will be described. In this case, the GMR film 40 of the second example is used instead of the GMR film 30 of the magnetoresistive effect element 20 shown in FIG. FIG. 3 is a cross-sectional view of a second example GMR film 40 as a GMR film included in the magnetoresistive effect element 20 according to the first embodiment. In the figure, portions corresponding to the portions described above are denoted by the same reference numerals, and description thereof is omitted.

  Referring to FIG. 3, the GMR film 40 of the second example includes an underlayer 31, a lower antiferromagnetic layer 32, a lower fixed magnetization stack 33, a lower nonmagnetic metal layer 37, a free magnetic layer 38, and an upper nonmagnetic metal. A layer 47, an upper pinned magnetization stack 43, an upper antiferromagnetic layer 42, and a protective layer 39. The GMR film 40 has a configuration in which the above layers are sequentially stacked. That is, in the GMR film 40, the upper nonmagnetic metal layer 47, the upper pinned magnetization stack 43, and the upper antiferromagnetic layer are provided between the free magnetic layer 38 and the protective layer 39 of the GMR film 30 of the first example shown in FIG. A layer 42 is provided. That is, the GMR film 40 of the second example has a so-called dual spin valve structure. Note that the lower antiferromagnetic layer 32, the lower pinned magnetization stack 33, and the lower nonmagnetic metal layer 34 are the antiferromagnetic layer 32, the pinned magnetization layer 33, the GMR film 30 of the first example shown in FIG. The same reference numerals are used because they have the same material and film thickness as the nonmagnetic metal layer 34. The upper nonmagnetic metal layer 47 and the upper antiferromagnetic layer 42 can be formed using the same materials as the lower nonmagnetic metal layer 37 and the lower antiferromagnetic layer 32, respectively. The film thicknesses of the upper nonmagnetic metal layer 47 and the upper antiferromagnetic layer 42 can also be set in the same range as the lower nonmagnetic metal layer 37 and the lower antiferromagnetic layer 32. The upper pinned magnetization stack 43 has a configuration in which an upper pinned layer 44, an upper nonmagnetic coupling layer 45, and an upper reference layer 46 are stacked in this order from the upper antiferromagnetic layer 42 side, that is, a so-called stacked ferrimagnetic structure. The upper pinned layer 44, the upper nonmagnetic coupling layer 45, and the upper reference layer 46 can be formed using the same materials as the lower pinned layer 34, the lower nonmagnetic coupling layer 35, and the lower reference layer 36, respectively. The film thicknesses of the upper pinned layer 44, upper nonmagnetic coupling layer 45, and upper reference layer 46 are set in the same ranges as the film thicknesses of the lower pinned layer 34, lower nonmagnetic coupling layer 35, and lower reference layer 36, respectively. Can do.

In the GMR film 40, each of the upper reference layer 46 and the lower reference layer 36 can be formed to have the same configuration as the reference layer 36 of the GMR film of the first example shown in FIG. That is, (Co _x Fe _100-x ) M _y (where 0 ≦ x ≦ 100, 0 <y <30 atomic%, M represents Ge, Si, or Mn) or (Co _x Mn _100-x ) M _y (Where 0 ≦ x ≦ 100, 0 <y <30 atomic%, M represents Ge, Si or Al). Or Co ₅₀ Fe ₂₅ Al _12.5 Si _12.5 , Co ₅₀ Fe ₂₅ Ge _12.5 Si _12.5 , Co ₅₀ Fe ₂₅ Ge _12.5 Al _12.5 , Co ₅₀ Fe ₂₅ Ge _12.5 Mn _12.5 , Co ₅₀ Fe ₂₅ Al _12.5 Mn _12.5 , or Co ₅₀ Fe ₂₅ Si _12.5 Mn _12.5 may be formed. Further, as shown in FIG. 3, an Al thin film, that is, Al is formed at the interface between each of the nonmagnetic layers 35, 37, 45, and 47 and each of the materials of the lower reference layer 36 and the upper reference layer 46. Diffusion prevention layers 1-1, 1-2, 1-3, and 1-4 are inserted. Alternatively, when each of the reference layers 46 and 36 has a laminated structure as described above, each of the nonmagnetic layers 35, 37 and 45, 47 and the respective laminated bodies as the reference layers 36, 46 At the interface, an Al thin film, that is, a diffusion preventing layer 1-1, 1-2, 1-3, and 1-4 formed of Al is inserted. In this case, the diffusion prevention layers 1-1, 1-2, 1-3, and 1-4 in which the Mn, Si, and Ge materials that are effective in increasing the specific resistance of the reference layers 36 and 46 are formed of Al. It is possible to diffuse into the nonmagnetic layers 35, 37, 45 and 47. At this time, the film thickness of each of the diffusion prevention layers 1-1, 1-2, 1-3, and 1-4 formed of Al is in a range of 0.1 nm to 1 nm that can be sputtered as a film. Is preferred. Due to such a laminated structure, the magnetoresistive effect element having the GMR film 40 of the second example has a large magnetoresistance change ΔRA for the same reason as that of the magnetoresistive effect element having the GMR film 30 of the first example. To have.

  Further, the GMR film 40 has a spin valve structure including a lower fixed magnetization stack 33, a lower nonmagnetic metal layer 37, and a free magnetization layer 38. Further, the GMR film 40 also has a spin valve structure including a free magnetic layer 38, an upper nonmagnetic metal layer 47, and an upper fixed magnetization stack 43. Therefore, in the GMR film 40, the magnetoresistance change amount ΔRA increases, and as a result, the GMR film 40 has a magnetoresistance change amount about twice the magnetoresistance change amount ΔRA of the GMR film 30 of the first example. . As a result, by using the GMR film 40 of the second example for the magnetoresistive effect element, it is possible to realize a magnetoresistive effect element with higher output than when the GMR film 30 of the first example is used. The method for forming the GMR film 40 is substantially the same as the method for forming the GMR film 30 of the first example described above, and a description thereof will be omitted.

6 to 8 are diagrams showing characteristics when a magnetic material containing Ge is used in the reference layer of the GMR film of Example 1 described above. FIG. 6 is a diagram showing the MR ratio representing the output with the Ge composition and thickness of the reference layer and the presence / absence of the diffusion prevention layer formed of Al as parameters. FIG. 7 is a diagram showing the sensitivity Hin of the reproducing element using the Ge composition and thickness of the reference layer and the presence / absence of a diffusion prevention layer formed of Al as parameters. FIG. 8 is a diagram showing Hua representing the reliability of the pinned layer using the Ge composition and thickness of the reference layer and the presence / absence of the diffusion prevention layer formed of Al as parameters. Here, the pinned layer refers to a laminated body of a pinned layer, a nonmagnetic coupling layer, and a reference layer (the same applies hereinafter). Here, each sample of Example 1 was produced as follows. On the silicon substrate on which the thermal oxide film was formed, a Cu (250 nm) / NiFe (50 nm) laminated film was formed as a lower electrode from the silicon substrate side. Next, do not heat the substrate using a sputtering apparatus in an ultrahigh vacuum (degree of vacuum: 2 × 10 ⁻⁶ Pa or less) layer of each of the laminated body from the base layer to the protective layer having the following composition and film thickness. Formed. Next, heat treatment was performed to make the antiferromagnetic layer appear antiferromagnetic. The heat treatment conditions were a heating temperature of 300 ° C., a treatment time of 3 hours, and an applied magnetic field of 1952 kA / m. Then, the thus obtained laminate was ground by ion milling, to produce a laminate, having six junction area in the range of 0.1μm ² ~0.6μm ^2. In addition, 40 laminated bodies were produced for each bonding area. Next, the laminated body thus obtained was covered with a silicon oxide film, then the protective layer was exposed by dry etching, and an upper electrode made of an Au film was formed so as to be in contact with the protective layer. The specific configuration of the GMR film of Example 1 is shown below. The numerical value in parentheses represents the film thickness. This also applies to the following embodiments.

Underlayer: Ru (4 nm)
Antiferromagnetic layer: IrMn (5 nm)
Pinned layer: Co ₆₀ Fe ₄₀ (2 nm)
Nonmagnetic coupling layer: Ru (0.72 nm)
Diffusion prevention layer: Al (0.25 nm)
Reference layer: CoFeGe (2-3 nm)
Diffusion prevention layer: Al (0.25 nm)
Nonmagnetic metal layer: Cu (3.5 nm)
Free magnetic layer: CoFeGe (4.5 nm)
Nonmagnetic metal layer: Cu (1.5 nm)
Protective layer: Ru (5 nm)
For these samples, the magnetoresistance change ΔR value was measured, and the average value of magnetoresistance change MR ratio (ΔRA / RA) was determined for each magnetoresistive effect element having the same junction area. The magnetoresistance change ΔR was measured as follows. That is, the current value of the sense current was set to 2 mA, and the external magnetic field was swept in the range of −79 kA / m to 79 kA / m parallel to the magnetization directions of the lower and upper second fixed magnetization layers (that is, the reference layer). Further, the voltage between the lower electrode and the upper electrode was measured with a digital voltmeter to obtain a magnetoresistance curve. Then, the magnetoresistance change ΔR was obtained from the difference between the maximum value and the minimum value of the magnetoresistance curve. Further, Hin and Hua described later were obtained from the hysteresis of the obtained magnetoresistance curve by sweeping the external magnetic field in the same direction as described above in the range of −7.9 kA / m to 7.9 kA / m. Here, as shown in FIG. 5, the term “Hin” represents the amount of magnetic field shift required for the change in resistance to respond when the direction of the external magnetic field changes. When the magnetic coupling force between the reference layer and the free magnetic layer is broken, the shift amount becomes small, and it becomes possible to react with sensitivity to an external magnetic field change. This Hin is mainly determined by the film thickness and roughness of the nonmagnetic intermediate layer. When the nonmagnetic intermediate layer is thin, or when the roughness is large and the reference layer and the free magnetic layer are partially magnetically coupled, the free magnetic layer can respond to the magnetic field from the medium with high sensitivity. Disappear. In such a case, a method of reducing Hin by increasing the thickness of the nonmagnetic intermediate layer is conceivable. However, in the case of the CPP type element, when the film thickness of the nonmagnetic intermediate layer is increased, the distance between the upper terminal and the lower terminal is increased, and the efficiency in the bit direction is lowered. For this reason, the thickness of the nonmagnetic intermediate layer is desirably 3.5 nm or less. Further, as a condition for functioning normally as a magnetoresistive effect element, it is required that at least Hin ≦ 15 [Oe]. Further, as shown in FIG. 5, Hua indicates the difference in magnetic field between the midpoint and the origin of the magnetoresistance curve when the resistance is lowered after the resistance is changed by changing the magnetic field from minus. . A large value Hua means that the magnetization curve is hardly affected by the external magnetic field. Therefore, it can be said that the higher the Hua, the more reliable the magnetoresistive film. Practically, Hua ≧ 2000 [Oe] is required.

FIG. 6 shows the result of actually creating a CPP-GMR element and measuring the MR ratio. The MR ratio increased when the Ge composition was increased from 20 atomic% to 30 atomic% regardless of whether or not a diffusion prevention layer formed of Al was inserted, and the MR ratio decreased when the Ge composition was increased to 35 atomic%. The decrease in MR at 30 atomic% or more is thought to be due to the fact that the magnetization of the magnetic layer suddenly decreased due to 35 atomic% of Ge and the MR decreased rather than the influence of diffusion. However, MR characteristics were improved by inserting a diffusion prevention layer made of Al under all conditions. In particular, the MR ratio was increased from 5.2% to 6.0% by inserting a diffusion prevention layer formed of Al under the condition of a film thickness of 3 nm of Co ₄₅ Fe ₂₅ Ge ₃₀ composition. FIG. 7 is a graph showing changes in Hin. Referring to the figure, when the thickness of the reference layer is 2 nm, the effect of the diffusion preventing layer formed of Al is not seen. However, in order to increase the MR ratio at Ge = 30 atomic%, when the reference layer was thickened to 3 nm and a diffusion prevention layer made of Al was used, Hin was reduced by about 30%. Conventionally, a reference layer of 3 nm at 30 atomic% showing a high MR ratio could not be realized due to the problem of roughness deterioration due to diffusion. On the other hand, it is possible to achieve both high MR and low Hin (≦ 15 [Oe]) by using the configuration of the embodiment.

  Further, with respect to Hua indicating the stability of the pinned layer, diffusion between the Ru layer and the CoFeGe layer is also prevented by using a diffusion prevention layer formed of Al, and 500 [Oe] is obtained under the film conditions of all reference layers. Increased. From this, the diffusion prevention layer formed of Al can compensate for a decrease in Hua due to an increase in the thickness of the reference layer, and Hua ≧ 2000 [Oe] can be achieved even under the condition where the thickness of the reference layer is increased. I understand.

  By inserting the diffusion prevention layer formed of Al between the reference layer and the adjacent layer as described above, CoFeGe that could not be applied to the magnetoresistive effect film due to the influence of element diffusion from the viewpoint of Hua and Hin. The composition and film thickness conditions can be applied to the magnetoresistive film. Further, by inserting the diffusion prevention layer formed of Al between the reference layer and the adjacent layer in this way, all the characteristics of MR ratio indicating output, Hin indicating sensitivity, and Hua indicating reliability are improved. It can be made. Further, in addition to Ge, a reference layer using an easily diffusing element such as Si or Mn is also effective for the diffusion prevention layer formed of Al.

  The magnetic head of Example 2 will be described below.

  The magnetic head of Example 2 has a tunnel magnetoresistance effect (hereinafter referred to as “TMR”) film as a magnetoresistance effect element. The configuration of the magnetic head of Example 2 is substantially the same as that of the magnetic head shown in FIG. 1 except that a TMR film is provided instead of the GMR film 30 in the magnetic head shown in FIG. Therefore, the description of the magnetic head itself is omitted.

  FIG. 4 is a sectional view of a TMR film 70 as a magnetoresistive effect element used in the magnetic head of the second embodiment. Referring to FIG. 4, the TMR film 70 is the same as the GMR film 30 except that the nonmagnetic metal layer 37 is replaced with a nonmagnetic insulating layer 37a formed of an insulating material in the GMR film 30 shown in FIG. It has the same configuration as.

  The nonmagnetic insulating layer 37a has a thickness of 0.2 nm to 2.0 nm, for example, and is formed of any one kind of oxide selected from the group consisting of Mg, Al, Ti, and Zr. Examples of such oxides include MgO, AlOx, TiOx, and ZrOx. Here, x in the above chemical formula can be any natural number other than 0. In particular, the nonmagnetic insulating layer 37a is preferably formed of crystalline MgO. In this case, it is preferable that the (001) surface of MgO is substantially parallel to the film surface, particularly in that the tunnel resistance change rate is increased. The nonmagnetic insulating layer 37a may be formed of any one nitride or oxynitride selected from the group consisting of Al, Ti, and Zr. Examples of such nitride include AlN, TiN, and ZrN. As a method for forming the nonmagnetic insulating layer 37a, the above materials may be directly formed using a sputtering method, a CVD method, or an evaporation method. Alternatively, after forming a metal film using a sputtering method, a CVD method or a vapor deposition method, an oxidation treatment or a nitriding treatment is performed to convert the metal film into an oxide film or a nitride film, thereby forming the nonmagnetic insulating layer 37a. Also good.

  The amount of change in tunnel resistance per unit area of the TMR film 70 of Example 2 can be measured in the same manner as the measurement of the amount of change in magnetoresistance ΔRA per unit area of the GMR film 30 of Example 1. The amount of change in tunnel resistance per unit area of the TMR film 70 of Example 2 increases as the polarizabilities of the free magnetic layer 38 and the pinned layer 36 increase. The polarizability is the polarizability of a ferromagnetic layer (free magnetic layer 38 and pinned layer 36) through an insulating layer (nonmagnetic insulating layer 37a). A magnetic material containing Ge, Si, or Mn is used for the reference layer 36, and a diffusion prevention film formed of ultrathin Al between each of the nonmagnetic coupling layer 35 and the nonmagnetic intermediate layer 37 and the reference layer 36. Insert. As a result, the output, sensitivity, and reliability obtained from the TMR film 70 are larger than those of NiFe and CoFe that have been conventionally used. Therefore, by using the same configuration as the reference layer 36 of the GRM film 30 of the first embodiment as the reference layer 36 of the TMR layer 40 of the second embodiment, characteristics similar to those of the GMR film 30 of the first embodiment are obtained. An improved magnetoresistive element can be obtained.

  Next, a magnetic storage device according to a third embodiment will be described with reference to the drawings.

  FIG. 9 is a plan view showing the main part of the magnetic storage device 90 of the third embodiment. Referring to FIG. 9, the magnetic storage device 90 has a housing 91. The housing 91 includes a hub 92 driven by a spindle (not shown), a magnetic recording medium 93 fixed to the hub 92 and rotated by the spindle, and an actuator unit 94. In the housing 91, an arm 95 and a suspension 96 supported by the actuator unit 94 and driven in the radial direction of the magnetic recording medium 93, and a magnetic head 98 supported by the suspension 96 are provided. The magnetic recording medium 93 may be either a longitudinal magnetic recording system or a perpendicular magnetic recording system, or a recording medium having oblique anisotropy. The magnetic recording medium 93 is not limited to a magnetic disk but may be a magnetic tape.

As shown in FIG. 1, the magnetic head 98 is formed of a magnetoresistive effect element 20 formed on the ceramic substrate 11 and an inductive recording element 13 formed thereon. The inductive recording element 13 may be a ring-type recording element for in-plane recording, a single-pole recording element for perpendicular magnetic recording, or another known recording element. The magnetoresistive element 20 includes any one of the GMR film of the first example and the second example of the first embodiment described above or the TMR film of the second embodiment. Therefore, the magnetoresistive effect element 20 has a large magnetoresistance change amount ΔRA per unit area or a tunnel resistance change amount per unit area, and the magnetoresistive effect element 20 has a high output. Therefore, the magnetic storage device 90 having such a magnetoresistive effect element 20 is suitable for high recording density recording. The basic configuration of the magnetic storage device 90 according to the third embodiment is not limited to that shown in FIG.

  Next, a magnetic memory device according to a first example of Embodiment 4 will be described with reference to the drawings.

  10A is a cross-sectional view of the magnetic memory device 100 of the first example of the fourth embodiment, and FIG. 10B is a diagram showing the configuration of the GMR film 30 shown in FIG. FIG. 12 is an equivalent circuit diagram of one memory cell 101 in the magnetic memory device 100 of the first example of the fourth embodiment. Note that in FIG. 10A, orthogonal coordinate axes are also shown to indicate directions. Among these, the Y1 and Y2 directions are directions perpendicular to the paper surface, the Y1 direction is a direction toward the back of the paper surface, and the Y2 direction is a direction toward the front of the paper surface. In the following description, for example, simply referring to the X direction indicates that either the X1 direction or the X2 direction may be used, and the same applies to the Y direction and the Z direction. In the figure, the same reference numerals are assigned to the portions corresponding to the portions described above, and the description thereof is omitted.

  Referring to FIGS. 10A, 10B, and 12, the magnetic memory device 100 includes a plurality of memory cells 101 arranged in a matrix, for example. The memory cell 101 includes a magnetoresistive effect (GMR) film 30 and a MOS field effect transistor (FET) 102. As the MOS FET 102, a p-channel MOS type FET or an n-channel MOS type FET can be used. Here, an n-channel MOS FET in which electrons are carriers will be described as an example of the MOS FET 102. The MOS type FET 102 has a p well region 104 containing a p type impurity formed in the silicon substrate 103. The MOS type FET 102 also has impurity diffusion regions 105 a and 105 b in which n type impurities are introduced apart from each other in the vicinity of the surface of the silicon substrate 103 in the p well region 104. Here, one impurity diffusion region 105a is a source S, and the other impurity diffusion region 105b is a drain D. In the MOS type FET 102, a gate electrode G is provided on the surface of the silicon substrate 103 between the two impurity diffusion regions 105a and 105b via a gate insulating film 106.

  The source S of the MOS type FET 102 is electrically connected to one side of the GMR film 30, for example, the base layer 31 through the vertical wiring 114 and the intralayer wiring 115. In addition, the plate line 108 is electrically connected to the drain D of the MOS FET 102 via the vertical wiring 114. The gate electrode G of the MOS FET 103 is electrically connected to the read word line 109. In this case, the gate electrode G may also serve as the read word line 109. The bit line 101 is electrically connected to the other side of the GMR film 30, for example, the protective film 39. A write word line 111 is provided below the GMR film 30 at a distance. The GMR film 30 has the same configuration as the GMR film 30 shown in FIG. In this GMR film 30, the direction of the easy axis of the free magnetic layer 38 is set along the X-axis direction shown in FIG. 10A, and the direction of the hard axis is set along the Y direction. The direction of the easy axis of magnetization may be formed by heat treatment or by shape anisotropy. When the easy magnetization axis is formed in the X-axis direction due to shape anisotropy, the cross-sectional shape parallel to the film surface of the GMR film 30 (the cross-sectional shape parallel to the XY plane) is set in the X direction rather than the side in the Y direction. A rectangle with a long side.

  In the magnetic memory device 100, the surface of the silicon substrate 103 and the gate electrode G are covered with an interlayer insulating film 113 such as a silicon nitride film or a silicon oxide film. Further, the GMR film 30, the plate line 108, the read word line 109, the bit line 110, the write word line 111, the vertical wiring 114, and the intra-layer wiring 115 are the interlayer insulating film 113 except for the electrical connection described above. Are electrically insulated from each other.

  In the magnetic memory device 100, information is held in the GMR film 30. In this case, information is held depending on whether the magnetization direction of the free magnetic layer 38 is parallel to or anti-parallel to the magnetization direction of the second pinned magnetic layer 36.

  Next, write and read operations of the magnetic memory device 100 will be described.

  The information write operation to the GMR film 30 of the magnetic memory device 100 is performed by the bit lines 110 and the write word lines 111 arranged above and below the GMR film 30. The bit line 110 extends along the X direction above the GMR film 30. By passing a current through the bit line 110, a magnetic field in the Y direction is applied to the GMR film 30. The write word line 111 extends along the Y direction below the GMR film 30. By passing a current through the write word line 111, a magnetic field in the X direction is applied to the GMR film 30. When the magnetic field is not substantially applied, the magnetization of the free magnetic layer 38 of the GMR film 30 faces the X direction (for example, the X2 direction), and the magnetization direction is stable.

  When information is written to the GMR film 30, a current is simultaneously applied to the bit line 110 and the write word line 111. For example, when the magnetization of the free magnetic layer 38 is directed in the X1 direction, a current in the Y1 direction is passed as a current passed through the write word line 111. Thereby, the magnetic field applied to the GMR film 30 becomes a magnetic field in the X1 direction. At this time, the direction of the current flowing through the bit line 110 may be either the X1 direction or the X2 direction. The magnetic field generated by the current flowing through the bit line 110 becomes a magnetic field in the Y1 direction or the Y2 direction in the GMR film 30, and functions as part of the magnetic field for the magnetization of the free magnetic layer 38 to cross the barrier of the hard axis. That is, a magnetic field in the X1 direction and a magnetic field in the Y1 direction or the Y2 direction are simultaneously applied to the free magnetic layer 38. As a result, the magnetization of the free magnetic layer 38 facing the X2 direction is reversed in the X1 direction. Even after the magnetic field is removed, the magnetization of the free magnetic layer 38 is in the X1 direction, and the direction of this magnetic field is stable unless a magnetic field for the next write operation or a magnetic field for erasure is applied.

  In this manner, information of “1” or “0” can be recorded in the GMR film 30 according to the magnetization direction of the free magnetic layer 38. For example, when the magnetization direction of the second pinned magnetic layer 36 is the X1 direction, information of “1” is recorded when the magnetization direction of the free magnetic layer 38 is the X1 direction (the tunnel resistance value is low). Treat as. In this case, similarly, when the magnetization direction of the free magnetic layer 38 is the X2 direction (the state where the tunnel resistance value is high), it is treated that information of “0” is recorded. Note that the magnitude of the current supplied to the bit line 110 and the write word line 111 during the write operation is such that the free magnetization is applied even if the current flows only in either the bit line 110 or the write word line 111. The size of the layer 38 is set so as not to cause reversal of magnetization. As a result, information is recorded only for the magnetization of the free magnetic layer 38 of the GMR film 30 at the intersection of the bit line 110 supplied with current and the write word line 111 supplied with current. During the write operation, the source S side is set to high impedance so that no current flows through the GMR film 30 when a current is passed through the bit line 110.

  Next, an operation of reading information from the GMR film 30 of the magnetic memory device 100 will be described. Information is read by applying a negative voltage with respect to the source S to the bit line 110 and applying a voltage (positive voltage) higher than the threshold voltage of the MOS FET 102 to the read word line 109, that is, the gate electrode G. As a result, the MOS FET 102 is turned on, and electrons flow from the bit line 110 to the plate line 108 via the GMR film 30, the source S, and the drain D. By electrically connecting a current value detector 118 such as an ammeter to the plate line 108, a magnetoresistance value corresponding to the magnetization direction of the free magnetic layer 38 relative to the magnetization direction of the second pinned magnetic layer 36 is detected. be able to. Thereby, “1” or “0” information held by the GMR film 30 can be read.

  In the magnetic memory device 100 of the first example of Example 4, a magnetic material containing Ge, Si or Mn is used for the reference layer 36 of the GMR film 30. Further, diffusion preventing layers 1-1 and 1-2 made of ultrathin Al are inserted between the nonmagnetic coupling layer 35 and the nonmagnetic intermediate layer 37 of the GMR film 30 and the reference layer 36, respectively. As a result, the output, sensitivity, and reliability of the GMR film 30 are large. Therefore, in the magnetic memory device 100 using the GMR film 30, when information is read out, the information is accurately determined by the difference between the magnetoresistive values corresponding to the retained “0” information and “1” information. Can be read out. Note that the GMR film 30 included in the magnetic memory device 100 may be replaced with any one of the GMR films 40 and 50 shown in FIGS.

  FIG. 12 is a configuration diagram of the TMR film 70 included in the magnetic memory device according to a modification of the magnetic memory device 100 according to the first example. Referring to FIG. 12 together with FIG. 10A, in the magnetic memory device of the modification shown in FIG. 12, the TMR film 70 is used instead of the GMR film 30 included in the magnetic memory device 100 shown in FIG. . The TMR film 70 has the same configuration as the TMR film 70 of the first example included in the magnetoresistive effect element of Example 2 described above. For the TMR film 70, for example, the base layer 31 is in contact with the in-layer wiring 115 and the protective film 39 is in contact with the bit line 110. Further, the easy axis of the free magnetic layer 38 of the TMR film 70 is set in the same manner as in the GMR film 30 described above. Since the write operation and the read operation of the magnetic memory device using the TMR film 70 are the same as the write operation and the read operation of the magnetic memory device using the GMR film 30 described above, description thereof is omitted.

  The TMR film 70 exhibits a tunnel resistance effect as described in the second embodiment. A magnetic material containing Ge, Si, or Mn is used as the reference layer 36 of the TMR film 70, and is formed of ultrathin Al between each of the nonmagnetic coupling layer 35 and the nonmagnetic intermediate layer 37 and the reference layer 36. Diffusion prevention layers 1-1 and 1-2 are inserted. As a result, the output, sensitivity, and reliability of the TMR film 70 are large. Therefore, in the magnetic memory device using the TMR film 70, when the information is read, the amount of change in the tunnel resistance corresponding to each of “0” and “1” held is large, so that accurate reading can be performed.

  FIG. 13 is a cross-sectional view of the magnetic memory device of the second example of the fourth embodiment. In the figure, portions corresponding to the portions described above are denoted by the same reference numerals, and description thereof is omitted. Referring to FIG. 13, the magnetic memory device 120 according to the fourth embodiment is different from that in the magnetic memory device 100 according to the first example described above with reference to FIG.

  The memory cell of the magnetic memory device 120 has the same configuration as the memory cell 101 shown in FIGS. 10A and 10B except that the write word line 111 is not provided. Hereinafter, description will be made with reference to FIG.

  In the case of this magnetic memory device 120, the write operation is different from that in the case of the magnetic memory device 100 of the first example. In the case of the magnetic memory device 120, a polarized spin current Iw is injected into the GMR film 30, and the magnetization direction of the free magnetic layer 38 is parallel to the magnetization direction of the second pinned magnetic layer 36 depending on the direction of the current. Invert from state to antiparallel state. Alternatively, the magnetization direction of the free magnetic layer 38 is inverted from the antiparallel state to the parallel state with respect to the magnetization direction of the second pinned magnetic layer 36 according to the current direction of the polarized spin current Iw. The polarized spin current Iw is an electron flow composed of electrons in one of two spin directions that can be taken by electrons. By causing the polarized spin current Iw to flow in the Z1 direction or the Z2 direction of the GMR film 30, torque is generated in the magnetization of the free magnetic layer, and so-called spin injection magnetization reversal is caused. The amount of the polarized spin current Iw is appropriately selected according to the film thickness of the free magnetic layer 38, and is about several mA to 20 mA. In this case, the amount of the polarized spin current Iw is smaller than the amount of current flowing through the bit line 110 and the write word line 111 during the write operation of the magnetic memory device 100 of the first example of FIG. . Therefore, power consumption can be reduced.

  The polarized spin current can be generated by flowing a current perpendicularly to a stacked body having a structure substantially similar to that of the GMR film 30 and sandwiching a Cu film between two ferromagnetic layers. In this case, the direction of electron spin can be controlled by setting the magnetization directions of these two ferromagnetic layers to be parallel or antiparallel. The reading operation of the magnetic memory device 120 is the same as the reading operation of the magnetic memory device 100 of the first example of FIG.

  The magnetic memory device 120 of the second example has the same effect as that of the magnetic memory device 100 of the first example. Furthermore, the magnetic memory device 120 of the second example can reduce the power consumption as described above compared to the magnetic memory device 100 of the first example. In the magnetic memory devices 100 and 120 of the first example and the second example of the fourth embodiment, the current direction during the write operation and the read operation is controlled by the MOS type FET 102, but by other known means. This current direction control may be performed.

  Although the preferred embodiments have been described in detail, the present invention is not limited to these specific embodiments, and various modifications and changes can be made. For example, in the third embodiment, the case where the magnetic recording medium is in the form of a disk has been described as an example. Further, the magnetic head including the magnetoresistive effect element and the recording element has been described as an example, but a magnetic head including only the magnetoresistive effect element may be used. Furthermore, a magnetic head in which a plurality of magnetoresistive elements are arranged may be used.

  Next, with reference to FIG. 14, as a description of the basis for using Al as the material of the diffusion prevention layer formed of Al used in each example, the results compared with the case where other elements are used will be described.

FIG. 14 shows the experimental results of CPP-GMR characteristics when various nonmagnetic metals other than Al are used for the intermediate layer X. The film configuration in the experiment is as follows.

NiCr (4nm)
IrMn (5 nm)
Co ₆₀ Fe (4 nm)
Ru (0.7 nm)
Fe ₆₀ Co (4 nm)
X (3nm)
Fe ₆₀ Co ₄₀ (7nm)
X (3nm)
Fe ₆₀ Co (4 nm)
Ru (0.7 nm)
Co ₆₀ Fe ₄₀ (4.5nm)
IrMn (5 nm)
Ru (5 nm)
(X represents Cu, Mg, Ti, Ru, Ta, Hf, NiCr or Rh)

FIG. 14 shows that when the magnetic alloy and these metals Cu, Mg, Ti, Ru, Ta, Hf, NiCr, or Rh are adjacent to each other, the MR ratio is greatly reduced. Therefore, it can be seen that when a layer made of these alloys is used in place of the diffusion prevention layer formed of Al, the magnetoresistance effect itself does not occur and is inappropriate.

  Next, the reason why Al is suitable as a diffusion preventing layer in each of the above embodiments will be further described with reference to FIG.

  FIG. 15 shows diffusion coefficients (Cu is self-diffusion) with respect to Cu of Ge, Si, Mn, which are limited as diffusing elements, and Co, Fe used as a magnetic material in each example (metal material data). Book Maruzen). Each diffusion coefficient value shown in the figure is a value at a pin annealing temperature of 300 ° C. of the antiferromagnetic layer. FIG. 15 shows that Al is an element that has a very small diffusion coefficient of 1/3 to 1/9 compared with other elements forming the reference layer, and is difficult to diffuse. From the value of the atomic radius of each element shown in FIG. 15, it can be seen that Al has a relatively large radius of 1.4 mm among nonmagnetic metals other than transition metals. Thus, the large difference between the atomic radius of Al and the atomic radius of Cu as the intermediate layer is considered to be a cause of a small Al diffusion coefficient, that is, Al is difficult to diffuse. It can also be seen that the difference in atomic radius between Al and the easily diffusing element Mn, Ge or Si is larger than the difference in atomic radius between Al and Cu. Therefore, it is considered that the penetration of Mn, Ge, or Si having an atomic radius close to that of Cu can be prevented by inserting a diffusion prevention layer made of Al at the interface with the intermediate layer Cu.

  Next, the basis of the composition of the reference layer 36 in each of the above embodiments will be described with reference to FIG.

  FIG. 16 shows the experimental results of the relationship between the Al composition range and Bs (magnetic flux density) in the CoMnAl composition. From this experimental result, it can be seen that when Al is mixed up to 35 atomic% in the composition of CoMnAl, the magnetic flux density in that case is reduced to about half that when Al is mixed at 15 atomic%. Since the strength of the magnetic moment of the magnetic layer is expressed by film thickness × Bs, when Bs is halved in this way, twice the film thickness is necessary to maintain predetermined characteristics. Become. In the CPP-GMR film, the increase in the film thickness leads to an increase in the read gap, which goes against the future high recording density. Therefore, it can be seen that application to a magnetic head having a nonmagnetic metal composition of 30 atomic% or more is difficult. Therefore, the upper limit of the Al composition range in the CoMnAl composition is set to 30 atomic%.

FIG. 3 is a diagram illustrating a main part of a medium facing surface of the magnetic head according to the first embodiment. 3 is a cross-sectional view of a first example GMR film included in the magnetoresistive element of Example 1. FIG. 6 is a cross-sectional view of a second example GMR film included in the magnetoresistive element of Example 1. FIG. 6 is a cross-sectional view of a TMR film of a first example included in a magnetoresistive element of Example 2. FIG. It is a schematic diagram showing Hin and Hua in the curve of a magnetoresistive effect. It is a figure which shows MR ratio when the composition of the reference layer of Example 1, film thickness, and the presence or absence of the diffusion prevention layer formed with Al are used as parameters. It is a figure which shows Hin when the composition of the reference layer of Example 1, a film thickness, and the presence or absence of the diffusion prevention layer formed with Al are used as parameters. It is a figure which shows Hua when the composition of the reference layer of Example 1, the film thickness, and the presence or absence of the diffusion prevention layer formed of Al are used as parameters. FIG. 6 is a plan view showing a main part of a magnetic storage device according to a third embodiment. (A) is sectional drawing of the magnetic memory device of the 1st example of Example 4, (B) is a block diagram of the GMR film | membrane shown to (A). FIG. 4 is an equivalent circuit diagram of one memory cell in the magnetic memory device of the first example. It is a block diagram of the TMR film | membrane which the modification of the magnetic memory device of a 1st example has. 6 is a sectional view of a magnetic memory device according to a second example of Example 4. FIG. It is a figure which shows MR ratio at the time of using various nonmagnetic metals for an intermediate | middle layer. It is a figure which shows the diffusion coefficient and atomic radius of each nonmagnetic metal with respect to Cu. _(Co 2 _Mn) is a diagram showing a Bs of Al composition dependency of _100-x Al _x.

Explanation of symbols

1-1, 1-2, 1-3, 1-4 Diffusion preventive layer formed of Al 10, 98 Magnetic head 20 Magnetoresistive element 30, 40 GMR film 32 Antiferromagnetic layer (lower antiferromagnetic layer)
34 Pinned layer (lower pinned layer)
35 Nonmagnetic coupling layer (lower nonmagnetic coupling layer)
36 Reference layer (lower reference layer)
37 Nonmagnetic intermediate layer (lower nonmagnetic intermediate layer)
37a Nonmagnetic insulating layer 38 Free magnetic layer 42 Upper antiferromagnetic layer 44 Upper pinned layer 45 Upper nonmagnetic coupling layer 46 Upper reference layer 47 Upper nonmagnetic intermediate layer 70 TMR film 90 Magnetic storage device 93 Magnetic recording medium 100, 120 Magnetic Memory device 101 Memory cell

Claims (8)

An antiferromagnetic layer;
A pinned layer formed on top of the diamagnetic layer;
A nonmagnetic coupling layer formed on the pinned layer;
A reference layer formed on the nonmagnetic coupling layer;
A nonmagnetic intermediate layer formed on the reference layer;
A free magnetic layer formed on the nonmagnetic intermediate layer,
The antiferromagnetic layer, the pinned layer, the nonmagnetic coupling layer, the reference layer, the nonmagnetic intermediate layer, and the free magnetic layer form a spin valve structure,
The reference layer has a magnetic material containing at least one element of Ge, Si and Mn,
Further, a first diffusion prevention layer formed below the reference layer and above the nonmagnetic coupling layer, and a second diffusion formed above the reference layer and below the nonmagnetic intermediate layer. Having at least one diffusion preventing layer of the preventing layers,
The CPP type magnetoresistive effect element, wherein the at least one diffusion preventing layer has an Al thin film. The reference layer is (Co _x Fe _100-x ) My (where 0 ≦ x ≦ ₁₀₀ , 0 <y <30 atomic%, and M represents any element of Ge, Si, and Mn) , (Co _x Mn _100-x ) My (where 0 ≦ x ≦ ₁₀₀ , 0 <y <30 atomic%, M represents one of Ge, Si and Al), Co ₅₀ Fe ₂₅ Al _12.5 Si _12.5 , Co ₅₀ Fe ₂₅ Ge _12.5 Si _12.5 , Co ₅₀ Fe ₂₅ Ge _12.5 Al _12.5 , Co ₅₀ Fe ₂₅ Ge _12.5 Mn _12.5 , Co ₅₀ Fe ₂₅ Al _12.5 Mn _12.5 or Co ₅₀ Fe ₂₅ Si _12.5 Mn _12.5 The magnetoresistive effect element according to claim 1, comprising: 3. The magnetoresistive element according to claim 1, wherein a thickness of an Al thin film included in the at least one diffusion prevention layer is in a range of 0.1 to 1.0 [nm]. A lower antiferromagnetic layer,
A lower pinned layer formed on the lower antiferromagnetic layer;
A lower nonmagnetic coupling layer formed on the lower pinned layer;
A lower reference layer formed on the lower nonmagnetic coupling layer;
A lower nonmagnetic intermediate layer formed on the lower reference layer;
A free magnetic layer formed on the lower nonmagnetic intermediate layer;
An upper nonmagnetic intermediate layer formed on the free magnetic layer;
An upper reference layer formed on top of the upper nonmagnetic intermediate layer;
An upper nonmagnetic coupling layer formed on the upper reference layer;
An upper pinned layer formed on the upper nonmagnetic coupling layer;
An upper antiferromagnetic layer formed on the upper pinned layer;
The lower antiferromagnetic layer, the lower pinned layer, the lower nonmagnetic coupling layer, the lower reference layer, the lower nonmagnetic intermediate layer, the free magnetic layer, and the upper nonmagnetic intermediate layer, The upper reference layer, the upper nonmagnetic coupling layer, the upper pinned layer, and the upper antiferromagnetic layer form a dual type spin valve structure,
Each of the lower reference layer and the upper reference layer includes a magnetic material containing at least one element of Ge, Si, and Mn,
A first diffusion prevention layer formed below the lower reference layer and above the lower nonmagnetic coupling layer; and a first diffusion prevention layer formed above the lower reference layer and below the lower nonmagnetic intermediate layer. An anti-diffusion layer, a third anti-diffusion layer formed below the upper reference layer and above the upper nonmagnetic intermediate layer, and an upper portion of the upper reference layer and the upper nonmagnetic coupling layer. Having at least one diffusion preventing layer of the fourth diffusion preventing layer formed in the lower part;
The CPP type magnetoresistive effect element, wherein the at least one diffusion preventing layer has an Al thin film. An antiferromagnetic layer;
A pinned layer formed on top of the diamagnetic layer;
A nonmagnetic coupling layer formed on the pinned layer;
A reference layer formed on the nonmagnetic coupling layer;
An oxide layer formed on the reference layer;
A free magnetic layer formed on the oxide layer,
The antiferromagnetic layer, the pinned layer, the nonmagnetic coupling layer, the reference layer, the oxide layer, and the free magnetic layer form a spin valve structure,
The reference layer has a magnetic material containing at least one element of Ge, Si and Mn,
Further, a first diffusion prevention layer formed below the reference layer and above the nonmagnetic coupling layer, and a second diffusion prevention layer formed above the reference layer and below the oxide layer. Having at least one anti-diffusion layer of
The CPP type magnetoresistive effect element, wherein the at least one diffusion preventing layer has an Al thin film. A magnetic head for recording information on a magnetic recording medium or reproducing information from the magnetic recording medium in a magnetic storage device,
A magnetic head comprising the magnetoresistive effect element according to claim 1. A magnetic recording medium for recording information;
A magnetic head for recording information on the magnetic recording medium or reproducing information from the magnetic recording medium,
A magnetic storage device according to claim 6, wherein the magnetic head is a magnetic head. A magnetoresistive effect element according to any one of claims 1 to 5,
Magnetic field applying means for applying a magnetic field from the outside to the magnetoresistive effect element,
A magnetic memory device for recording information by changing a magnetization direction of the free magnetic layer of the magnetoresistive effect element by applying a magnetic field by the magnetic field applying means.

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