JP5814898B2 - Magnetoresistive element and manufacturing method thereof - Google Patents

Description

  Embodiments described herein relate generally to a magnetoresistive element that senses magnetism by causing a sense current to flow in a direction perpendicular to the film surface of the magnetoresistive film, and a method of manufacturing the same.

  In recent years, hard disk drives (HDDs) have been rapidly reduced in size and density, and further increases in density are expected in the future. By increasing the track density by narrowing the recording track width, it is possible to increase the density of the HDD. However, when the track width is narrowed, the magnitude of the recorded magnetization, that is, the recording signal becomes small, and it is necessary to improve the reproduction sensitivity of the MR head that reproduces the medium signal.

  Recently, a GMR head including a high-sensitivity spin-valve film using a giant magnetoresistive effect (GMR) has been adopted. The spin valve film is a laminated film having a sandwich structure in which a spacer layer is sandwiched between two ferromagnetic layers, and the laminated film structure site causing a resistance change is also called a spin-dependent scattering unit. The magnetization direction of one of the two ferromagnetic layers (referred to as “pinned layer” or “magnetization pinned layer”) is fixed by an antiferromagnetic layer or the like. The magnetization direction of the other ferromagnetic layer (referred to as “free layer” or “magnetization free layer”) can be changed by an external magnetic field. In the spin valve film, a large magnetoresistance effect is obtained by changing the relative angle of the magnetization direction of the two ferromagnetic layers.

  Examples of magnetoresistive elements using spin valve films include CIP (Current In Plane) -GMR elements, CPP (Current Perpendicular to Plane) -GMR elements, and TMR (Tunneling Magneto-Resistance) elements. In the CIP-GMR element, a sense current is passed in parallel to the surface of the spin valve film, and in the CPP-GMR and TMR elements, a sense current is passed in a direction substantially perpendicular to the surface of the spin valve film.

  In the method of energizing perpendicular to the film surface, an insulating layer is used as a spacer layer in a TMR element, and a metal layer is used as a spacer layer in a normal CPP-GMR.

  Here, in the metal CPP-GMR element in which the spin valve film is formed of a metal layer, a resistance change amount due to magnetization is small, and it is difficult to detect a weak magnetic field. In view of such a problem, in JP2003-133614A and JP2003-60263A, Cr, V, Ta, Nb, Sc, Ti, in the magnetization fixed layer and the magnetization free layer constituting the spin-dependent scattering unit, Mn, Cu, Zn, Ga, Ge, Zr, Hf, Y, Tc, Re, Ru, Rh, Ir, Pd, Pt, Ag, Au, B, Al, In, C, Si, Sn, Ca, Sr, Attempts have been made to increase the magnetoresistance effect by inserting a layer composed of at least one element selected from the group consisting of Ba, O, N, and F to increase the amount of change in resistance of the CPP-GMR. ing.

  On the other hand, apart from the above-described attempts, a CPP element in which the spacer layer constituting the CPP-GMR is not a simple metal layer but an oxide layer [NOL (nano-oxide layer)] including a current path in the thickness direction. Has been proposed (Japanese Patent Laid-Open No. 2002-208744). In this element, both the element resistance and the MR change rate can be increased by a current confinement [CCP (Current-confined-path)] effect. Such an element is called a CCP-CPP element.

JP 2003-133614 A JP 2003-60263 A JP 2002-208744 A

  The CCP-CPP element as described above is required to improve its sensitivity. As the sensitivity of the CCP-CPP element, an MR change rate can be given.

  In view of the above, an object of the present invention is to improve the MR change rate of a CCP-CPP element. It is another object of the present invention to provide a magnetic head, a magnetic disk device, and a magnetic memory using such a CCP-CPP element.

  The magnetoresistive effect element according to the embodiment includes a first electrode and a second electrode. Also, an antiferromagnetic layer provided between the first electrode and the second electrode, and a magnetization provided between the second electrode and the antiferromagnetic layer are substantially unidirectional. A pinned magnetic pinned layer; and a current confinement layer provided between the second electrode and the pinned magnetic layer and having an insulating layer and a conductor that allows current to pass through the insulating layer in the layer direction. Provided between a spacer layer, a magnetization free layer provided between the second electrode and the spacer layer, the magnetization of which changes with respect to an external magnetic field, and between the second electrode and the magnetization free layer With a thin film layer. Further, provided in at least one of the layer of the magnetization pinned layer, the layer of the magnetization free layer, the interface of the magnetization pinned layer and the spacer layer, and the interface of the magnetization free layer and the spacer layer, A functional layer containing one element selected from Mg, B, and Al, or one element selected from Si, Mg, B, and Al and one element selected from Co, Ni, and Fe With.

It is a perspective view showing an example of the basic composition of the magnetoresistive effect element of the present invention. It is a figure for demonstrating the MR improvement mechanism by functional layer insertion in the magnetoresistive effect element shown in FIG. It is sectional drawing which shows the modification of the magnetoresistive effect element shown in FIG. It is a schematic diagram which shows the outline of an example of the film-forming apparatus used for manufacture of the magnetoresistive effect element shown in FIG. It is a flowchart of the manufacturing process of the magnetoresistive effect element shown in FIG. FIG. 2 is a cross-sectional view showing a state in which the magnetoresistive element shown in FIG. Similarly, it is sectional drawing which shows the state which incorporated the magnetoresistive effect element shown in FIG. 1 in the magnetic head. It is a perspective view which shows an example of the magnetic recording / reproducing apparatus containing the magnetoresistive effect element of this invention. It is a figure which shows an example of the magnetic head assembly of this invention. It is a figure which shows an example of the magnetic memory matrix containing the magnetoresistive effect element of this invention. It is a figure which shows the other example of the magnetic memory matrix containing the magnetoresistive effect element of this invention. It is sectional drawing which shows the principal part of the magnetic memory which concerns on embodiment of this invention. It is sectional drawing which follows the A-A 'line of FIG.

  According to the magnetoresistive effect element of the embodiment, at least one of the magnetization pinned layer, the magnetization free layer, the magnetization pinned layer and the spacer layer interface, and the magnetization free layer and the spacer layer interface, A functional layer containing Si, Mg, B, and Al is provided. As will be described in detail below, this functional layer captures excess oxygen present in the spin-dependent scattering unit of the magnetoresistive effect element and suppresses diffusion of this excess oxygen into the magnetic pinned layer and the magnetic free layer. As a result, it is possible to suppress a decrease in spin-dependent scattering due to the presence in the magnetization free layer and at the interface. Further, since the functional layer is composed of an element having a small atomic number such as Si, Mg, B, and Al, the spin-polarized conduction electrons do not lose the spin polarization in the functional layer.

  The functional layer functions to suppress diffusion of Mn contained in the magnetization pinned layer and Ni contained in the magnetization free layer, thereby reducing the spin-dependent interface scattering caused by the element such as Ni. Can be suppressed. Furthermore, when the magnetization free layer has a bcc structure, the structure of the magnetization free layer can be stabilized by the presence of the functional layer described above. As a result, the MR change rate of the obtained magnetoresistive effect element, that is, the CCP-CPP element can be increased by the three actions described above.

  Note that the above-described three actions are based solely on the considerations of the present inventors, and do not affect the feasibility of this embodiment. The present embodiment is characterized in that in the so-called CCP-CPP element, the MR change rate can be improved by providing a functional layer that satisfies the above-described requirements.

  According to another aspect of the present invention, the spacer layer is adjacent to at least one of the current confinement layer, the magnetization fixed layer, and the magnetization free layer, for example, any one of Cu, Ag, and Au. A metal layer containing can be formed. When the metal layer is formed between the current confinement layer and the magnetization fixed layer, the metal layer functions as a supply source constituting a current path of the current confinement layer and , Function as a protective layer against oxides, nitrides, oxynitrides and the like contained in the current confinement layer. When the metal layer is formed between the current confinement layer and the magnetization free layer, the metal layer includes an oxide, a nitride, and an oxynitride included in the current confinement layer of the magnetization free layer. It functions as a protective layer against things.

  Hereinafter, other features of the present invention, a manufacturing method, and an application example to a magnetic head will be described with reference to the drawings.

(Magnetoresistive element: CCP-CPP element)
FIG. 1 is a perspective view showing an example of a magnetoresistive effect element (CCP-CPP element) of the present invention. Note that FIG. 1 and the subsequent drawings are all schematic views, and the ratio between the film thicknesses in the figure does not necessarily match the ratio between the actual film thicknesses.

  As shown in the figure, the magnetoresistive effect element according to the present embodiment includes a magnetoresistive effect film 10 and a lower electrode 11 and an upper electrode 20 that sandwich the magnetoresistive effect film 10 from above and below, and is configured on a substrate not shown. .

The magnetoresistive film 10 includes an underlayer 12, a pinning layer 13, a pin layer 14, a lower metal layer 15, a current confinement layer 16 (insulating layer 161, current path 162), an upper metal layer 17, a free layer 18, and a cap layer 19. Are sequentially stacked. Among these, the lower metal layer 15, the current confinement layer 16, and the upper metal layer 17 constitute a spacer layer, and the pin layer 14, the lower metal layer 15, the current confinement layer 16, the upper metal layer 17, and the free layer 18 This corresponds to a basic film configuration that exhibits a magnetoresistive effect in which a nonmagnetic spacer layer is sandwiched between two ferromagnetic layers, that is, a spin-dependent scattering unit (spin valve film). For ease of viewing, the current confinement layer 16 is shown in a state separated from its upper and lower layers (lower metal layer 15 and upper metal layer 17).
Hereinafter, components of the magnetoresistive element will be described.

<Electrode>
The lower electrode 11 is an electrode for energizing in the direction perpendicular to the spin valve film. When a voltage is applied between the lower electrode 11 and the upper electrode 20, a current flows through the inside of the spin valve film along the direction perpendicular to the film surface. By detecting a change in resistance caused by the magnetoresistive effect with this current, magnetism can be detected. For the lower electrode 11, a metal layer having a relatively small electric resistance is used in order to pass a current to the magnetoresistive effect element.

  Similar to the lower electrode, the upper electrode 20 is an electrode for energizing in the direction perpendicular to the spin valve film. When a voltage is applied between the lower electrode 11 and the upper electrode 20, a current in the vertical direction of the film flows in the spin valve film. The upper electrode 20 is made of an electrically low resistance material (for example, Cu, Au).

<Underlayer>
The underlayer 12 can be divided into, for example, a buffer layer 12a and a seed layer 12b. The buffer layer 12a is a layer for reducing the roughness of the surface of the lower electrode 11. The seed layer 12b is a layer for controlling the crystal orientation and crystal grain size of the spin valve film formed thereon.

  As the buffer layer 12a, Ta, Ti, V, W, Zr, Hf, Cr, or an alloy thereof can be used. The thickness of the buffer layer 12a is preferably about 1 to 10 nm, and more preferably about 2 to 5 nm. If the buffer layer 12a is too thin, the buffer effect is lost. On the other hand, if the buffer layer 12a is too thick, the series resistance that does not contribute to the MR change rate is increased. When the seed layer 12b formed on the buffer layer 12a has a buffer effect, the buffer layer 12a is not necessarily provided. As a preferred example, Ta [3 nm] can be used.

  The seed layer 12b may be any material that can control the crystal orientation of the layer formed thereon. As the seed layer 12b, an fcc structure (face-centered cubic structure), an hcp structure (hexagonal close-packed structure), or a bcc structure (body-centered cubic structure) A metal layer having a structure is preferable.

  For example, by using Ru having an hcp structure or NiFe having an fcc structure as the seed layer 12b, the crystal orientation of the spin valve film thereon can be changed to the fcc (111) orientation. Further, when the pinning layer 13 is IrMn, good fcc (111) orientation is realized, and when the pinning layer 13 is PtMn, a regular fct (111) structure (face-centered tetragonal structure) Is obtained. Further, when fcc metal is used as the magnetic layer, good fcc (111) orientation can be realized, and when bcc metal is used as the magnetic layer, good bcc (110) orientation can be obtained.

  In order to sufficiently exhibit the function as the seed layer 12b for improving the crystal orientation, the film thickness of the seed layer 12b is preferably 1 to 5 nm, more preferably 1.5 to 3 nm. As a preferred example, Ru [2 nm] can be used.

  The crystal orientation of the spin valve film and the pinning layer 13 can be measured by X-ray diffraction. Good orientation is obtained by setting the full width at half maximum of the rocking curve at the fcc (111) peak of the spin valve film, the fct (111) peak of the pinning layer 13 (PtMn), or the bcc (110) peak to 3.5 to 6 degrees. be able to. The orientation dispersion angle can also be determined from a diffraction spot using a cross-sectional TEM.

As the seed layer 12b, a NiFe-based alloy (for example, Ni _x Fe _100-x (x = 90 to 50%, preferably 75 to 85%) or a third element X is added to NiFe instead of Ru. and the non-magnetic _{(Ni x Fe 100-x)} 100-y X y (X = Cr, V, Nb, Hf, Zr, Mo)) can also be used. In the NiFe-based seed layer 12b, it is relatively easy to obtain good crystal orientation, and the half-value width of the rocking curve measured in the same manner as described above can be 3 to 5 degrees.

  The seed layer 12b has not only a function of improving the crystal orientation but also a function of controlling the crystal grain size of the spin valve film. Specifically, the crystal grain size of the spin valve film can be controlled to 5 to 20 nm, and even when the size of the magnetoresistive element is reduced, a high MR change rate can be realized without causing variation in characteristics.

  The crystal grain size of the spin valve film can be determined by the grain size of the crystal grains of the layer disposed between the seed layer 12b and the spacer layer 16 (for example, it can be determined by a cross-sectional TEM or the like). For example, when the pinned layer 14 is a bottom type spin valve film positioned below the spacer layer 16, the pinning layer 13 (antiferromagnetic layer) or the pinned layer 14 ( It can be determined by the crystal grain size of the magnetization pinned layer.

  In a reproducing head compatible with high-density recording, the element size is surely a fine size of 100 nm or less. When the ratio of the crystal grain size to the element size is large, the characteristics of the element vary, and it is not preferable that the crystal grain size of the spin valve film is larger than 20 nm.

  When the number of crystal grains per element area decreases, it may cause variation in characteristics due to the small number of crystals, so it is not preferable to increase the crystal grain size. In particular, it is not preferable to increase the crystal grain size in a CCP-CPP element in which a current path is formed.

  On the other hand, when the crystal grain size is larger, there are fewer electron irregular reflections and inelastic scattering sites due to grain boundaries. For this reason, in order to realize a large MR change rate, it is preferable that the crystal grain size is large, and it is necessary that it is at least 5 nm or more. As described above, the requirements for the crystal grain size in terms of MR change rate and in terms of eliminating variations among elements are mutually contradictory and have a trade-off relationship. A preferable range of the crystal grain size in consideration of this trade-off relationship is 5 to 20 nm.

In order to obtain the crystal grain size of 5~20nm described above, as the seed layer 12b, Ru _{and, (Ni x Fe 100-x} ) 100-y X y (X = Cr, V, Nb, Hf, Zr, Mo )) In the case of a layer, the composition y of the third element X is preferably about 0 to 30% (including the case where y is 0%).

  As described above, the thickness of the seed layer 12b is preferably about 1 nm to 5 nm, and more preferably 1.5 to 3 nm. If the thickness of the seed layer 12b is too thin, effects such as crystal orientation control are lost. On the other hand, if the thickness of the seed layer 12b is too thick, the series resistance may be increased, and unevenness at the interface of the spin valve film may be caused.

  Note that materials other than those listed here may be used for the seed layer 12b as long as a good seed layer 12b with a fine crystal grain size can be realized.

<Pinning layer>
The pinning layer 13 has a function of fixing magnetization by imparting unidirectional anisotropy to a ferromagnetic layer to be a pinned layer 14 formed thereon. As a material of the pinning layer 13, an antiferromagnetic material such as PtMn, PdPtMn, IrMn, RuRhMn can be used. Of these, IrMn is advantageous as a material for a head corresponding to a high recording density. IrMn can apply unidirectional anisotropy with a film thickness smaller than that of PtMn, and is suitable for narrowing the gap necessary for high-density recording.

  In order to impart sufficient strength of unidirectional anisotropy, the film thickness of the pinning layer 13 is appropriately set. When the material of the pinning layer 13 is PtMn or PdPtMn, the thickness is preferably about 8 to 20 nm, and more preferably 10 to 15 nm. When the material of the pinning layer 13 is IrMn, unidirectional anisotropy can be imparted even with a thinner film thickness such as PtMn, preferably 4 to 18 nm, more preferably 5 to 15 nm. As a preferred example, IrMn [7 nm] can be used.

As the pinning layer 13, a hard magnetic layer can be used instead of the antiferromagnetic layer. As a hard magnetic layer, for _{example, CoPt (Co = 50~85%)} , (Co x Pt 100-x) 100-y Cr y (x = 50~85%, y = 0~40%), FePt (Pt = 40-60%) can be used. Since the hard magnetic layer (especially CoPt) has a relatively small specific resistance, an increase in the series resistance and the area resistance RA can be suppressed.

<Pin layer: Magnetized pinned layer>
The pinned layer 14 includes a lower pinned layer 141 (for example, Co ₉₀ Fe ₁₀ 3.5 nm), a magnetic coupling layer 142 (for example, Ru), and an upper pinned layer 143 (for example, Fe ₅₀ Co ₅₀ [1 nm] / Cu [0] .25 nm]) × 2 / Fe ₅₀ Co ₅₀ [1 nm]) is a preferred example. The pinning layer 13 (for example, IrMn) and the lower pinned layer 141 immediately above the pinning layer 13 are exchange-magnetically coupled so as to have unidirectional anisotropy. The lower pinned layer 141 and the upper pinned layer 143 above and below the magnetic coupling layer 142 are strongly magnetically coupled so that the magnetization directions are antiparallel to each other.

As a material of the lower pinned layer 141, for example, a Co _x Fe _100-x alloy (x = 0 to 100%), a Ni _x Fe _100-x alloy (x = 0 to 100%), or a nonmagnetic element is added thereto Can be used. Further, as the material of the lower pinned layer 141, a single element of Co, Fe, Ni or an alloy thereof may be used.

The magnetic film thickness (saturation magnetization Bs × film thickness t (Bs · t product)) of the lower pinned layer 141 is preferably substantially equal to the magnetic film thickness of the upper pinned layer 143. That is, it is preferable that the magnetic film thickness of the upper pinned layer 143 and the magnetic film thickness of the lower pinned layer 141 correspond. As an example, when the upper pinned layer 143 is (Fe ₅₀ Co ₅₀ [1 nm] / Cu [0.25 nm]) × 2 / Fe ₅₀ Co ₅₀ [1 nm], the saturation magnetization of Fe ₅₀ Co _{50 in} the thin film is about 2 Therefore, the magnetic film thickness is 2.2T × 3 nm = 6.6 Tnm. Since the saturation magnetization of Co ₉₀ Fe ₁₀ is about 1.8 T, the thickness t of the lower pinned layer 141 that gives the same magnetic thickness as above is 6.6 Tnm / 1.8T = 3.66 nm. Therefore, it is desirable to use Co ₉₀ Fe ₁₀ having a film thickness of about 3.6 nm. When Co ₇₅ Fe ₂₅ is used, the film thickness is preferably about 3.3 nm from the same calculation.

The thickness of the magnetic layer used for the lower pinned layer 141 is preferably about 2 to 5 nm. Based on the unidirectional anisotropic magnetic field strength due to the pinning layer 13 (eg, IrMn) and the antiferromagnetic coupling magnetic field strength between the lower pinned layer 141 and the upper pinned layer 143 via the magnetic coupling layer 142 (eg, Ru) . If the lower pinned layer 141 is too thin, the upper pinned layer 143 that affects the MR change rate must also be made thin, so the MR change rate becomes small. On the other hand, if the lower pinned layer 141 is too thick, it is difficult to obtain a sufficient unidirectional anisotropic magnetic field necessary for device operation. A preferred example is Co ₇₅ Fe ₂₅ having a thickness of 3.3 nm.

  The magnetic coupling layer 142 (for example, Ru) has a function of forming a synthetic pin structure by causing antiferromagnetic coupling in the upper and lower magnetic layers (lower pinned layer 141 and upper pinned layer 143). The film thickness of the Ru layer as the magnetic coupling layer 142 is preferably 0.8 to 1 nm. Note that any material other than Ru may be used as long as the material causes sufficient antiferromagnetic coupling in the upper and lower magnetic layers. Instead of the film thickness of 0.8 to 1 nm corresponding to the 2nd peak of RKKY (Ruderman-Kittel-Kasuya-Yosida) bond, the film thickness of 0.3 to 0.6 nm corresponding to the 1st peak of RKKY bond can also be used. . Here, as an example, 0.9 nm of Ru, which can stably obtain a highly reliable coupling, is obtained.

As described above, a magnetic layer such as (Fe ₅₀ Co ₅₀ [1 nm] / Cu [0.25 nm]) × 2 / Fe ₅₀ Co ₅₀ [1 nm] can be used as an example of the upper pinned layer 143. The upper pinned layer 143 forms part of the spin dependent scattering unit. The upper pinned layer 143 is a magnetic layer that directly contributes to the MR effect, and both the constituent material and the film thickness are important in order to obtain a large MR change rate. In particular, the magnetic material located at the interface with the spacer layer 16 is particularly important in that it contributes to spin-dependent interface scattering.

The effect of using the Fe ₅₀ Co ₅₀ having the bcc structure used here as the upper pinned layer 143 will be described. When a magnetic material having a bcc structure is used as the upper pinned layer 143, a large MR change rate can be realized because the spin-dependent interface scattering effect is large. Examples of the FeCo-based alloy having a bcc structure include Fe _x Co _100-x (x = 30 to 100%) and those obtained by adding an additive element to Fe _x Co _100-x . Among these, Fe ₄₀ Co ₆₀ to Fe ₈₀ Co ₂₀ satisfying all the characteristics are examples of easy-to-use materials.

  When the upper pinned layer 143 is formed of a magnetic layer having a bcc structure that easily realizes a high MR ratio, the total thickness of the magnetic layer is preferably 1.5 nm or more. This is to keep the bcc structure stable. Since the metal material used for the spin valve film often has an fcc structure or an fct structure, only the upper pinned layer 143 may have a bcc structure. For this reason, if the film thickness of the upper pinned layer 143 is too thin, it becomes difficult to keep the bcc structure stable, and a high MR ratio cannot be obtained.

Here, as the upper pinned layer 143, Fe ₅₀ Co ₅₀ including an ultrathin Cu stack is used. Here, the upper pinned layer 143 is made of FeCo having a total film thickness of 3 nm and Cu having a thickness of 0.25 nm stacked for every 1 nm of FeCo, and has a total film thickness of 3.5 nm.

  As the film thickness of the upper pinned layer 143 is larger, it is easier to obtain a large MR change rate. However, in order to obtain a large pinned magnetic field, a thinner film is preferable, and a trade-off relationship exists. For example, when an FeCo alloy layer having a bcc structure is used, it is necessary to stabilize the bcc structure, and thus a film thickness of 1.5 nm or more is preferable. Also, when a CoFe alloy layer having an fcc structure is used, a film thickness of 1.5 nm or more is also preferable in order to obtain a large MR ratio. On the other hand, in order to obtain a large pinned magnetic field, the thickness of the upper pinned layer 143 is preferably 5 nm or less, more preferably 4 nm or less. As described above, the film thickness of the upper pinned layer 143 is preferably 1.5 nm to 5 nm, and more preferably about 2.0 nm to 4 nm.

For the upper pinned layer 143, instead of a magnetic material having a bcc structure, a Co ₉₀ Fe ₁₀ alloy having an fcc structure widely used in a conventional magnetoresistive effect element, Co having an hcp structure, or a cobalt alloy is used. Can be used. As the upper pinned layer 143, any single metal such as Co, Fe, Ni, or an alloy material containing any one of these elements can be used. When the magnetic material of the upper pinned layer 143 is arranged from those advantageous for obtaining a large MR ratio, an FeCo alloy material having a bcc structure, a cobalt alloy having a cobalt composition of 50% or more, and an Ni composition of 50% or more are obtained. It becomes the order of nickel alloy.

Further, as the upper pinned layer 143, a Heusler magnetic alloy layer such as Co ₂ MnGe, Co ₂ MnSi, or Co ₂ MnAl can be used.

  In this example, the upper pinned layer 143 is formed by alternately laminating magnetic layers (FeCo layers) and nonmagnetic layers (ultra-thin Cu layers). In the upper pinned layer 143 having a laminated structure with such a nonmagnetic element material, a spin-dependent scattering effect called a spin-dependent bulk scattering effect can be improved by an ultrathin Cu layer.

  The “spin-dependent bulk scattering effect” is used as a paired term with the spin-dependent interface scattering effect. The spin-dependent bulk scattering effect is a phenomenon that manifests the MR effect inside the magnetic layer. The spin-dependent interface scattering effect is a phenomenon in which the MR effect is exhibited at the interface between the spacer layer and the magnetic layer.

Hereinafter, the improvement of the bulk scattering effect by the laminated structure of the magnetic layer and the nonmagnetic layer will be described.
In the CCP-CPP element, since the current is confined in the vicinity of the spacer layer 16, the contribution of resistance in the vicinity of the interface of the spacer layer 16 is very large. That is, the ratio of the resistance at the interface between the spacer layer 16 and the magnetic layer (the pinned layer 14 and the free layer 18) to the resistance of the entire magnetoresistive element is large. This indicates that the contribution of the spin-dependent interface scattering effect is very large and important in the CCP-CPP element. That is, the selection of the magnetic material positioned at the interface of the spacer layer 16 has a very important meaning as compared with the case of the conventional CPP element. This is the reason why an FeCo alloy layer having a bcc structure with a large spin-dependent interface scattering effect is used as the upper pinned layer 143, as described above.

  However, the use of a material having a large spin-dependent bulk scattering effect cannot be ignored, and is still important for obtaining a higher MR change rate. The film thickness of the ultrathin Cu layer for obtaining the spin-dependent bulk scattering effect is preferably 0.1 nm to 1 nm, and more preferably 0.2 nm to 0.5 nm. When the Cu layer is too thin, the effect of improving the spin-dependent bulk scattering effect is weakened. If the Cu layer is too thick, the spin-dependent bulk scattering effect may be reduced, and the magnetic coupling of the upper and lower magnetic layers via the nonmagnetic Cu layer becomes weak, and the characteristics of the pinned layer 14 are insufficient. It becomes. Therefore, in a preferable example, 0.4 nm of Cu was used.

  As a material for the nonmagnetic layer between the magnetic layers, Hf, Zr, Ti, or the like may be used instead of Cu. On the other hand, when these ultra-thin nonmagnetic layers are inserted, the film thickness of one magnetic layer such as FeCo is preferably 0.5 nm to 2 nm, more preferably about 1 nm to 1.5 nm.

As the upper pinned layer 143, a layer obtained by alloying FeCo and Cu may be used instead of the alternately laminated structure of the FeCo layer and the Cu layer. Examples of such an FeCoCu alloy include (Fe _x Co _100-x ) _100-y Cu _y (x = 30 to 100%, y = about 3 to 15%), but other composition ranges are used. May be. Here, as an element added to FeCo, other elements such as Hf, Zr, and Ti may be used instead of Cu.

The upper pinned layer 143 may be a single layer film made of Co, Fe, Ni, or an alloy material thereof. For example, as the upper pinned layer 143 having the simplest structure, a 2 to 4 nm Co ₉₀ Fe ₁₀ single layer that has been widely used in the past may be used. Other elements may be added to this material.

  In the present embodiment, as shown in FIG. 1, the functional layer 21 containing Si, Mg, B, and Al is inserted (formed) into the lower pinned layer 141 and the upper pinned layer 143. This functional layer has a function different from the improvement of the spin-dependent bulk scattering effect by the nonmagnetic insertion layer made of Cu or the like shown in Patent Documents 1 and 2, for example. Only when the functional layer 21 is inserted into the CCP-GMR film of the CCP-CPP element as shown in the present embodiment, a large MR change rate can be achieved. Details of the functional layer 21 will be described later.

  The functional layer 21 is formed inside the lower pinned layer 141 and the upper pinned layer 143, but is not necessarily required to be formed on both, and can be formed on either one. Further, it is not formed inside the lower pinned layer 141 and the upper pinned layer 143, but is formed between the surface portions, for example, the upper pinned layer 143 and the lower metal layer 15 of the spacer layer described below. You can also. Furthermore, the functional layer 21 may be formed only in the free layer and / or the cap layer as described below without being formed in the pinned layer.

<Spacer layer>
The lower metal layer 15 is used for forming the current path 162 and is a supply source of the current path 162. The lower metal layer 15 also has a function as a stopper layer that suppresses oxidation of the upper pinned layer 143 located in the lower portion when the upper insulating layer 161 is formed.

  When the constituent material of the current path 162 is Cu, the constituent material of the lower metal layer 15 is preferably the same (Cu). When the constituent material of the current path 162 is a magnetic material, this magnetic material may be the same as or different from the magnetic material of the pinned layer 14. As a constituent material of the current path 162, Au, Ag, or the like may be used in addition to Cu.

  The current confinement layer 16 includes an insulating layer 161 and a current path 162. The insulating layer 161 is made of oxide, nitride, oxynitride, or the like. In order to exhibit the function as the spacer layer, the thickness of the insulating layer 161 is preferably 1 nm to 3 nm, and more preferably 1.5 nm to 2.5 nm.

  The current path 162 is a path (path) through which current flows perpendicularly to the film surface of the current confinement layer 16 and is used to confine the current. It functions as a conductor that allows current to pass in the direction perpendicular to the film surface of the insulating layer 161, and can be composed of, for example, a metal layer such as Cu. That is, the current confinement layer 16 has a current confinement structure (CCP structure), and the MR change rate can be increased by the current confinement effect. Examples of the material forming the current path 162 (CCP) include Au, Ag, Ni, Co, Fe, or an alloy layer including at least one of these elements, in addition to Cu. As an example, the current path 162 can be formed of an alloy layer containing Cu. An alloy layer such as CuNi, CuCo, or CuFe can also be used. Here, a composition having 50% or more of Cu is preferable in order to reduce the high MR ratio and the interlayer coupling field (Hin) between the pinned layer 14 and the free layer 18.

  The current path 162 is a region where the contents of oxygen and nitrogen are significantly smaller than those of the insulating layer 161 (there is a difference in the content of oxygen and nitrogen at least twice) and is a crystalline phase. Since the crystalline phase has a smaller resistance than the amorphous phase, it easily functions as the current path 162.

The upper metal layer 17 serves as a barrier layer for suppressing diffusion of oxygen and nitrogen constituting the current confinement layer 16 into the free layer 18 and as a seed layer for promoting good crystal growth of the free layer 18. Function. Specifically, the upper metal layer 17 protects the free layer 18 formed thereon from being oxidized or nitrided in contact with the oxide / nitride / oxynitride of the current confinement layer 16. That is, the upper metal layer 17 limits the direct contact between oxygen in the oxide layer of the current path 162 and the free layer 18. Further, the upper metal layer 17 improves the crystallinity of the free layer 18. For example, when the material of the insulating layer 161 is amorphous (for example, Al ₂ O ₃ ), the upper metal layer 17 has a metal layer formed thereon. Although the crystallinity deteriorates, the crystallinity of the free layer 18 can be remarkably improved by disposing an extremely thin seed layer (for example, a Cu layer) that improves the crystallinity.

  The material of the upper metal layer 17 is preferably the same as the material (for example, Cu) of the current path 162 of the current confinement layer 16. When the material of the upper metal layer 17 is different from the material of the current path 162, the interface resistance is increased. However, if both are the same material, the interface resistance is not increased. When the constituent material of the current path 162 is a magnetic material, this magnetic material may be the same as or different from the magnetic material of the free layer 18. As a constituent material of the upper metal layer 17, Au, Ag, or the like can be used in addition to Cu.

<Free layer: Magnetization free layer>
The free layer 18 is a layer having a ferromagnetic material whose magnetization direction is changed by an external magnetic field. For example, a two-layer configuration of Co ₉₀ Fe ₁₀ [1 nm] / Ni ₈₃ Fe ₁₇ [3.5 nm] using NiFe with CoFe inserted at the interface is an example of the free layer 18. In this case, it is preferable to provide a CoFe alloy at the interface with the current confinement layer 16 rather than a NiFe alloy in order to realize a large MR ratio. In order to obtain a high MR ratio, selection of the magnetic material of the free layer 18 located at the interface of the current confinement layer 16 is important. In the case where the NiFe layer is not used, a Co ₉₀ Fe ₁₀ [4 nm] single layer can also be used. Further, a free layer 18 having a three-layer structure such as CoFe / NiFe / CoFe may be used. Further, as will be described later, an amorphous alloy layer such as CoZrNb may be used as a part of the free layer 18.

Among the CoFe alloys, Co ₉₀ Fe ₁₀ is preferable because the soft magnetic characteristics are stable. When a CoFe alloy near Co ₉₀ Fe ₁₀ is used, the film thickness is preferably 0.5 nm to 4 nm. In addition, Co _x Fe _100-x (x = 70 to 90) is a preferable composition range that can be used.

  Alternatively, a free layer 18 may be used in which a CoFe layer or Fe layer of 1 nm to 2 nm and an ultrathin Cu layer of about 0.1 nm to 0.8 nm are alternately stacked.

Of the materials forming the current confinement layer 16, when the current path layer 162 through which a current flows is formed of a Cu layer, as in the pinned layer 14, the bcc FeCo layer is replaced with the current confinement layer 16 in the free layer 18. When used as an interface material, the MR change rate increases. As an interface material with the current confinement layer 16, a bcc FeCo alloy may be used instead of the fcc CoFe alloy. In this case, Fe _x Co _100-x (x = 30 to 100) in which a bcc layer is easily formed, or a material obtained by adding an additive element thereto can be used. For example, Co ₅₀ Fe ₅₀ [1 nm] / Ni ₈₅ Fe ₁₅ [3.5 nm] can be used.

  Further, an amorphous magnetic layer such as CoZrNb may be used as a part of the free layer 18. However, even when an amorphous magnetic layer is used, it is necessary to use a magnetic layer having a crystal structure at the interface in contact with the spacer layer 16 that greatly affects the MR ratio. The structure of the free layer 18 can be configured as follows when viewed from the spacer layer 16 side. That is, the structure of the free layer 18 may be (1) crystal layer only, (2) crystal layer / amorphous layer stack, (3) crystal layer / amorphous layer / crystal layer stack, and the like. What is important here is that in any of (1) to (3), the crystal layer is always in contact with the interface with the spacer layer 16.

  In this embodiment, a functional layer 21 containing Si, Mg, B, and Al is inserted (formed) in the free layer 18 as shown in FIG. As described in the case of the pinned layer, this functional layer has a function different from the improvement of the spin-dependent bulk scattering effect by the nonmagnetic insertion layer made of Cu or the like shown in Patent Documents 1 and 2, for example. doing. Only when the functional layer 21 is inserted into the CCP-GMR film of the CCP-CPP element as shown in the present embodiment, a large MR change rate can be achieved. Details of the functional layer 21 will be described later.

  Although the functional layer 21 is formed inside the free layer 18, it is formed between the surface portion, for example, the free layer 18 and the upper metal layer 17 of the spacer layer described below. You can also Furthermore, the functional layer 21 can be formed only in the cap layer as described below without being formed in the free layer, and can be formed only in the pinned layer as described above. .

<Cap layer>
The cap layer 19 has a function of protecting the spin valve film. The cap layer 19 can have, for example, a plurality of metal layers, for example, a two-layer structure of a Cu layer and a Ru layer (Cu [1 nm] / Ru [10 nm]). As the cap layer 19, a Ru / Cu layer in which Ru is disposed on the free layer 18 side can also be used. In this case, the film thickness of Ru is preferably about 0.5 to 2 nm. The cap layer 19 having this configuration is particularly desirable when the free layer 18 is made of NiFe. This is because Ru has a non-solid relationship with Ni, so that magnetostriction of the interface mixing layer formed between the free layer 18 and the cap layer 19 can be reduced.

  When the cap layer 19 is Cu / Ru or Ru / Cu, the thickness of the Cu layer is preferably about 0.5 to 10 nm, and the thickness of the Ru layer can be about 0.5 to 5 nm. . Since Ru has a high specific resistance value, it is not preferable to use a very thick Ru layer.

  As the cap layer 19, another metal layer may be provided instead of the Cu layer or the Ru layer. The configuration of the cap layer 19 is not particularly limited, and other materials may be used as long as the cap can protect the spin valve film. However, care should be taken because the MR ratio and long-term reliability may change depending on the selection of the cap layer. Cu and Ru are examples of desirable cap layer materials from these viewpoints.

  In the present embodiment, a functional layer 21 containing Si, Mg, B, and Al is inserted (formed) into the cap layer 19 as shown in FIG. As described in the case of the pinned layer, this functional layer has a function different from the improvement of the spin-dependent bulk scattering effect by the nonmagnetic insertion layer made of Cu or the like shown in Patent Documents 1 and 2, for example. doing. Only when the functional layer 21 is inserted into the CCP-GMR film of the CCP-CPP element as shown in the present embodiment, a large MR change rate can be achieved. Details of the functional layer 21 will be described later.

  The functional layer 21 is formed inside the cap layer 19, but may be formed on the surface portion thereof, for example, between the free layer 18 and the cap layer 17. Furthermore, the functional layer 21 can be formed only on the pinned layer and / or the free layer as described above without being formed on the cap layer.

  In the present embodiment, the functional layer 21 containing Si, Mg, B, and Al is inserted into at least one of the lower pinned layer 141, the upper pinned layer 143, the free layer 18 and the cap layer 19 described above, so that FIG. The MR ratio of the magnetoresistive effect element (CCP-CPP element) having the configuration shown in FIG. As described above, the techniques disclosed in Patent Documents 1 and 2 improve spin-dependent bulk scattering by forming an insertion layer similar to the functional layer, and as a result, increase the MR ratio. However, in the functional layer of the present embodiment (the present invention), as described below, the MR change rate is not increased by conventional spin-dependent bulk scattering.

(Details of functional layer)
The present inventors insert a functional layer made of Si into at least one of the lower pinned layer 141, the upper pinned layer 143, the free layer 18 or the cap layer 19 of the magnetoresistive effect element shown in FIG. I found that the rate of change improved. The film configuration of the magnetoresistive film that has been confirmed to improve the MR ratio is shown below. The film configuration of a CCP-GMR film without insertion of a Si functional layer is shown.

・ Lower electrode 11
・ Underlayer 12: Ta [5 nm] / Ru [2 nm]
Pinning layer 13: Ir ₂₂ Mn ₇₈ [7 nm]
Pinned layer 14: Co ₇₅ Fe ₂₅ [3.3 nm] / Ru [0.9 nm] / (Fe ₅₀ Co ₅₀ [1 nm] / Cu [0.25 nm]) × 2 / Fe ₅₀ Co ₅₀ [1 nm]
Metal layer 15: Cu [0.6 nm]
Current confinement layer 16: Al ₂ O ₃ insulating layer 161 and Cu current path 162 Metal layer 17: Cu [0.25 nm]
Metal layer 17: Cu [0.4nm]
Free layer 18: Fe ₄₀ Co ₆₀ [2 nm] / Si [0.25 nm] / Ni ₈₃ Fe ₁₇ [3.5 nm]
Cap layer 19: Cu [1 nm] / Ta [2 nm] / Ru [15 nm]
-Upper electrode 20

The MR ratio of the CCP-GMR film having the above-described film configuration was 11%. The MR ratio is 9.5% when Fe ₄₀ Co ₆₀ [2 nm] / Ni ₈₃ Fe ₁₇ [3.5 nm] in which no Si functional layer is inserted in the free layer 18 of the CCP-GMR film is used. is there. From the above results, it was confirmed that the MR ratio was improved by 1.5% by inserting the Si layer into the free layer 18 of the CCP-GMR film.

  In the above film configuration, improvement in MR change rate was confirmed by inserting Si into the free layer 18, but improvement in MR change rate was also confirmed in the same manner even when Si was inserted into the cap layer 19 and the pinned layer 14. Details of these results are given in the examples.

  Hereinafter, the reason why the structure of the magnetoresistive film of this embodiment is excellent in MR will be described in detail. However, at the present time, there is a part where the mechanism of improving MR has not been fully understood.

A. Consideration of mechanism for improving MR and reliability by inserting functional layer As a cause of improving MR and improving reliability by inserting a functional layer, the effect of trapping excess oxygen can be considered. FIG. 2A shows a cross-sectional view of a conventional CCP-GMR film in which no functional layer is inserted. In the film configuration of FIG. 2, since Al ₂ O ₃ is used as the insulating layer 161, surplus oxygen generated during the formation of Al ₂ O ₃ diffuses into the adjacent pinned layer 14 and free layer 18.

  Such diffusion of excess oxygen from the current confinement layer 16 to the pinned layer 14 and the free layer 18 causes oxidation of the magnetic materials Co, Fe, and Ni used in the pinned layer and the free layer. When CoO, FeO, and NiO generated by oxidation are present in the pinned layer 14 and the free layer 18, the spin-dependent bulk scattering is reduced. Further, if CoO, FeO, or NiO is present at the interface between the pinned layer 14 and the lower metal layer 15 or the interface between the upper metal layer 17 and the free layer 18, the spin-dependent interface scattering is lowered. Both of these phenomena lead to a decrease in MR. The conventional CCP-GMR film cannot exhibit the full potential of the GMR effect for the reasons described above, and in order to be mounted on a magnetic head for a magnetic recording apparatus having a higher recording density in the future, the insulating layer 162 is used. It is an effective means to prevent the diffusion of excess oxygen from.

  FIG. 2B shows a cross-sectional view when a functional layer is inserted into the CCP-GMR film shown in FIG. In FIG. 2B, Si is inserted as the functional layer 21 into the upper pinned layer 143 and Si is inserted as the functional layer 21 into the free layer 18. Table 1 shows a list of oxide formation energies of various elements. In Table 1, the lower the oxide formation energy, the easier it is to oxidize. From Table 1, Si is more easily oxidized than Co, Fe, and Ni used for the pinned layer 14 and the free layer 18. Therefore, oxygen in the free layer and the pinned layer collects in the inserted Si, causing reduction of Co, Fe, and Ni, and oxidation of Si. By inserting an element made of Si into the upper pinned layer 143 and the free layer 18 as a functional layer, formation of CoO, FeO, and NiO can be suppressed, and spin-dependent bulk scattering and spin-dependent interface scattering can be reduced. Can be suppressed. As a result, a high MR change rate can be obtained by exhibiting the full potential of the GMR effect.

  Here, the effect of improving the MR ratio cannot be obtained unless the elements used in the functional layer are appropriately selected. As shown in Table 1, in addition to Si, there are many elements that are more easily oxidized than Co, Fe, and Ni. For example, even when an element having a large atomic number such as Ta or Hf is inserted into the pinned layer or free layer, it is considered that the function of capturing excess oxygen is exhibited in the same manner as the Si element described above. However, when an element having a large atomic number, such as Ta or Hf, is used as a functional layer, the spin-polarized conduction electrons pass through the Ta, Hf layer having a large atomic number, and thus, spin-independent scattering due to spin-orbit interaction. Will cause. That is, even when magnetic elements such as Co, Ni, and Fe can exhibit the full potential of the GMR effect due to excess oxygen capture in the Ta and Hf layers, the conduction electrons lose spin polarization in the Ta and Hf layers, The spin-polarized conduction electrons do not efficiently reach the magnetic element, and as a result, the GMR effect is hindered, resulting in a decrease in MR change rate.

  On the other hand, since Si, which has been confirmed to improve MR in the present invention, is an element having a relatively small atomic number, scattering of electrons not dependent on spin does not occur as significantly as Ta and Hf, and does not inhibit the GMR effect. . That is, since the demerit of electron scattering independent of spin is not caused, and only the merit of the trapping effect of surplus oxygen can be enjoyed, the MR change rate of the CCP-GMR film can be improved. For the above reasons, Mg, B, and Al are listed as elements having a relatively small atomic number other than Si and being more easily oxidized than Co, Fe, and Ni. These elements can also be expected to improve the MR change rate of the CCP-GMR film by trapping excess oxygen, similar to Si.

In addition to the surplus oxygen trapping effect by the insertion layer, there is a possibility that the diffusion preventing effect has an effect on the improvement of the MR ratio by the functional layer insertion. When Mn contained in the pinning film 13 or Ni contained in the upper free layer diffuses in the vicinity of the current confinement layer, the specific resistance of the current path increases and the spin-dependent interface scattering decreases. Both of these phenomena lead to a decrease in MR change rate. For example, in the magnetoresistive film of FIG. 1, by inserting a functional layer made of Si into the upper pinned layer 143, diffusion of Mn contained in the pinning layer 13 to the vicinity of the current confinement layer 16 is suppressed, and the functional layer It is conceivable that the MR change rate due to the insertion of is improved. Further, for example, when Fe ₄₀ Co ₆₀ [2 nm] / Ni ₈₃ Fe ₁₇ [35 nm] is used as the free layer 18 in the magnetoresistive film of FIG. 1, Fe ₄₀ Co ₆₀ [2 nm] and Ni ₈₃ Fe ₁₇ [ In the case where Si [0.25 nm] is provided as a functional layer with respect to 35 nm], the diffusion of Ni into the current confinement layer 16 in the free layer 18 is suppressed, and the MR ratio is improved. .

  However, as will be described later, even when Si is inserted into the cap layer 19 as a functional layer, the effect of improving the MR ratio can be confirmed. Since the functional layer in this case is not disposed between the pinning layer and the current confinement layer, or between the Ni-containing layer and the current confinement layer inside the free layer, the role of the diffusion preventing layer of Mn and Ni is Not played. From this result, it is considered that the above-described effect of preventing diffusion of Mn and Ni is not at least the main cause of the improvement in MR ratio by the functional layer insertion of the present invention.

  As another mechanism for improving the MR ratio by insertion of the functional layer, stabilization of the bcc structure of the free layer 18 can be considered.

When a magnetic material having a bcc structure is used on the spacer layer interface side of the free layer 18, a large MR change rate can be realized because the spin-dependent interface scattering effect is large. However, if the free layer 18 is, for example, a single layer of Fe ₅₀ Co ₅₀ having a bcc structure, it is not preferable from the viewpoint of soft magnetic properties, and practically Fe ₅₀ Co ₅₀ [2 nm] / Ni ₉₀ Fe ₁₀ [3. 5 nm], it is desirable to have a laminated structure with a NiFe alloy having excellent soft magnetic properties. However, when such a laminated _structure, for Fe 50 _{Co 50} layers 1nm _thin, influenced by fcc structure of the NiFe alloy is provided on top of Fe 50 _{Co 50,} the Fe 50 _{Co 50} layers The bcc structure becomes unstable. Here, an Si layer is formed between the Fe ₅₀ Co ₅₀ having the bcc structure and the NiFe alloy having the fcc structure, such as Fe ₅₀ Co ₅₀ [2 nm] / Si [0.25 nm] / Ni ₉₀ Fe ₁₀ [3.5 nm]. It can be considered that the bcc structure of the Fe ₅₀ Co ₅₀ layer is stabilized by cutting the lattice matching between the Fe ₅₀ Co ₅₀ and the NiFe alloy.

  However, as described above, since the MR improvement effect has been confirmed even when the Si layer is inserted into the cap layer 19, the above-described bcc structure stabilization is considered to be at least not the main cause.

As described above, it is highly possible that the MR change rate improvement effect due to the functional layer insertion confirmed in the present invention is due to the capture of surplus oxygen from CCP-NOL. However, when the Si functional layer is inserted into the free layer 18 such that Fe ₅₀ Co ₅₀ [2 nm] / Si [0.25 nm] / Ni ₉₀ Fe ₁₀ [3.5 nm], the above-described Ni diffusion prevention is performed. The effect and the bcc stabilizing effect of the Fe ₅₀ Co ₅₀ layer may also function in addition to the excess oxygen trapping effect. For the above reason, the MR ratio can be improved by inserting the functional layer 21 in the CCP-GMR film.

B. Structure of functional layer In addition to Si, the functional layer 21 of the present embodiment can also use elements having lower oxidation energy and lower atomic number than Co, Ni, and Fe such as Mg, B, and Al. Magnetic coupling in the pinned layer 14 or the free layer 18 (that is, the upper and lower magnetic layers via the functional layer 21) by inserting Si, Mg, B, and Al, which are nonmagnetic materials, as the functional layer 21 May be disrupted. In order to keep the magnetic coupling through the functional layer 21 at a sufficiently large value, the thickness of the functional layer 21 is preferably 0.05 nm to 1 nm, more preferably 0.1 nm to 0.7 nm.

  On the other hand, when the functional layer 21 is used for the cap layer 19, there is no need to consider a problem such as the breaking of magnetic coupling. However, if it is too thick, the series resistance is increased, so 0.05 nm to 3 nm, more preferably 0.1 nm to 1 nm is desirable.

When the functional layer 21 is used in the pinned layer 14 and the free layer 18, a mixed layer of the magnetic elements Co, Ni, Fe and Si, Mg, B, Al may be used. For example, when a functional layer is inserted into the free layer 18 having a structure of Fe ₅₀ Co ₅₀ [2 nm] / Ni ₉₀ Fe ₁₀ [3.5 nm], an alloy layer obtained by adding Si to Fe ₅₀ Co ₅₀ or Ni ₉₀ Fe ₁₀ An alloy layer to which Si is added can be inserted as a functional layer. Here, when the mixed layer with the magnetic element is used as the functional layer, Si atoms spread in the film thickness direction as compared with the functional layer of the Si single layer. Therefore, the effect of locally capturing excess oxygen is Si. Weaker than single layer. However, as described above, even if the ability to capture surplus oxygen in one place is lower than that of the Si single layer, the MR ratio can be improved as compared with the case where no functional layer is inserted. In addition, when a mixed layer with a magnetic element is used as a functional layer, there is a merit that magnetic coupling between the upper and lower magnetic layers through the functional layer is easier than when using a single Si layer. A mixed layer of Fe and Si, Mg, B, or Al may be used.

  Here, when the case where it is added to the magnetic layer constituting the pinned layer 14 and the entire magnetic layer constituting the free layer 18 is considered, for example, a laminated magnetic layer such as FeCo / NiFe used as the free layer 18 is used. When Si is added as a whole, the free layer 18 of FeCoSi / NiFeSi is obtained. In this case, since Si that captures surplus oxygen is present in the entire free layer 18, the effect of collecting oxygen in one place when inserted as a functional layer is lost. That is, the insertion of Si in the present embodiment (the present invention) is meaningful only for insertion as a functional layer, and the effect of the present invention cannot be obtained even when used as an additive element to the entire magnetic layer.

  As the position where the functional layer 21 is disposed, it is not desirable to dispose it at a position far away from the spacer layer. The reason for this is that if the pinned layer 14 and the free layer 18 are disposed at a position far away from the spacer layer, excess oxygen in the portion close to the spacer layer cannot be trapped, and the current confinement layer 16 in which current confinement is performed. This is because surplus oxygen remains in the magnetic layer that most contributes to MR in the vicinity. The functional layer 21 is inserted into the pinned layer 14 in a region within 10 nm from the interface between the pinned layer 14 and the spacer layer to the film surface in the direction of the pinned layer 14, or the free layer 18. When inserted into the cap layer 19, it is desirable to dispose in a region within 10 nm from the interface between the spacer layer and the free layer 18 in the direction of the free layer 18 with respect to the film surface.

The functional layer 21 may be inserted into a plurality of layers such as the pinned layer 14, the free layer 18, and the cap layer 19. In such a case, for example, when a plurality of layers are inserted into the free layer 18, Fe ₅₀ Co ₅₀ [1 nm] / functional layer first layer Si [0.25 nm] / Ni ₉₀ Fe ₁₀ [1.5 nm] / function Second layer Si [0.25 nm] / Ni ₉₀ Fe ₁₀ [1.0 nm] / Functional layer third layer Si [0.25 nm] / Ni ₉₀ Fe ₁₀ [1.0 nm]. The distance between the first layer and the second layer, or the distance between the second layer and the third layer is preferably about 1 nm to 2 nm.

  As an advantage of using a plurality of functional layers 21, there is a point of enhancing the effect of capturing excess oxygen in the functional layers. A plurality of functional layers 21 may be inserted in the case of the pinned layer 14 or in the case of the free layer 18 and the cap layer 19. A plurality of layers may be inserted into both the pinned layer 14 and the free layer 18.

  As a demerit of using a plurality of functional layers 21, there is a possibility that magnetic characteristics are deteriorated due to weak magnetic coupling between the magnetic layers via the functional layer 21. In order to prevent the deterioration of the magnetic characteristics, it is preferable that the total thickness of the functional layer 21 in the pinned layer 14 and the free layer 18 is in the same thickness range as that of one layer. In addition, as described above, the distance between the plurality of functional layers 21 in one magnetic layer is preferably 1 to 2 nm.

The amount of increase in MR due to the insertion of the functional layer 21 differs depending on the material of the magnetic layer, and is large when the Fe composition is high. For example, in the following film configuration:
・ Lower electrode 11
・ Underlayer 12: Ta [5 nm] / Ru [2 nm]
Pinning layer 13: Ir ₂₂ Mn ₇₈ [7 nm]
Pinned layer 14: Co ₇₅ Fe ₂₅ [3.3 nm] / Ru [0.9 nm] / (Fe ₅₀ Co ₅ [1 nm] / Cu [0.25 nm]) × 2 / Fe ₅₀ Co ₅₀ [1 nm]
Lower metal layer 15: Cu [0.6 nm]
Current confinement layer 16: Al ₂ O ₃ insulating layer 161 and Cu current path 162
-Upper metal layer 17: Cu [0.4nm]
Free layer 18: described later Cap layer 19: Cu [1 nm] / Ta [2 nm] / Ru [15 nm]
-Upper electrode 20
The structure of the free layer 18 is Fe—Co [2 nm] / Si [0.25 nm] / Ni ₈₃ Fe ₁₇ [3.5 nm] (with a functional layer 21), and Fe—Co [2 nm] / Ni ₈₃ Fe ₁₇ [3 .5 nm] (with no functional layer 21), the composition of the Fe—Co alloy at the interface with the spacer layer in the free layer 18 and the amount of increase in MR due to Si insertion are compared, and the Fe composition is 10 [at.%]. ] Was improved by 0.5%, Fe composition was improved by 1.5% at 40 [at.%], And Fe composition was improved by 2.2% at 50 [at.%].

  From this result, it can be seen that when the Fe composition of the Fe—Co alloy disposed on the spacer layer interface side of the free layer 18 is large, the MR improvement due to Si insertion is large. Therefore, when the functional layer 21 is inserted into the magnetic layer, it is desirable that the Fe composition in the region within 1 nm from the spacer layer within the magnetic layer is 10 at% or more in order to obtain the MR improvement effect by inserting the functional layer 21, More preferably, it is 40 at% or more.

  In the magnetic layer having a high Fe composition, the difference in the oxidation energy of the magnetic element can be considered as the cause of the large MR increase due to the insertion of the functional layer 21. Among Co, Fe, and Ni, Fe has the lowest oxidation energy and is easily oxidized. When a magnetic material having a high Fe composition is used for the pinned layer 14 and the free layer 18, oxidation by surplus oxygen from CCP-NOL occurs easily, and surplus oxygen for the full potential of the GMR effect in the absence of surplus oxygen. The amount of MR degradation affected by the above is large. In such a magnetic layer in which the MR deterioration amount due to surplus oxygen is large, the MR recovery amount due to the trapping effect of surplus oxygen due to Si insertion is also large, so that the MR increase amount due to Si insertion is large. Among Co, Fe, and Ni, oxidation energy increases in the order of Fe, Ni, and Co. Therefore, the MR increase amount by the functional layer 21 is the highest in the magnetic layer having a large Fe content, and then Ni, Co It becomes the order of.

  The structure of the magnetoresistive film 10 in which the functional layer as described above is inserted can be confirmed by a three-dimensional atom probe. As the three-dimensional atom probe, for example, Local Electrode Atom Probe manufactured by Imago Scientific Instruments can be used.

  The three-dimensional atom probe microscope is a measurement method capable of mapping composition information in the atomic order of a material in three dimensions. Specifically, a high voltage is applied to a sample to be measured processed into a needle-shaped post having a radius of curvature of the tip of 30 to 100 nm and a height of about 100 μm. Then, the position of the atom that has been electrolytically evaporated from the tip of the sample to be measured is detected by a two-dimensional detector. Obtaining depth information in the z direction (x, y, z) by following the time course (time axis) of the position information of the atoms in the two-dimensional plane (x, y) detected by the two-dimensional detector A three-dimensional structure can be observed.

  In addition to the apparatus of Imago Scientific Instruments, it is also possible to analyze using Oxford Instruments, Cameca, or a three-dimensional atom probe having an equivalent function. In general, a voltage pulse is applied to cause electrolytic evaporation, but a laser pulse may be used instead of the voltage pulse. In either case, a DC voltage is used to add a bias field. In the case of voltage pulses, the voltage ignites the electric field required for field evaporation. In the case of a laser pulse, electric field evaporation is caused by raising the temperature locally so that electric field evaporation is likely to occur.

  The structure of the magnetoresistive film 10 with the functional layer inserted as described above can also be specified by locally performing elemental analysis by EDX in the cross-sectional TEM image.

In the present embodiment, FIG. 1 shows a bottom type CCP-GMR film, but a top type CCP-GMR film is formed, and according to the above-described method (form), A functional layer can be inserted as appropriate. FIG. 3 shows a cross-sectional view of a top type CCP-GMR film provided with a functional layer 21. In the case of the top type, instead of inserting the functional layer 21 into the cap layer 19 on the bottom side, the functional layer 21 can be inserted into the base layer 12.
Next, the CCP-CPP element of this embodiment will be described in comparison with other reference examples.

C. Comparison with the case where Si is inserted into the metal CPP-GMR film In the metal CPP-GMR film, the technology that enhances the spin-dependent bulk scattering and improves the MR ratio by inserting Cu into the magnetic layer is not patented. It is published in Document 1 (Non-Patent Document 1: H. Yuasa et al., J. Appl. Phys. 92 (5), 2646 (2002)). Further, in Patent Document 1 (Japanese Patent Laid-Open No. 2003-133614) and Patent Document 2 (Japanese Patent Laid-Open No. 2003-60263) described above, an insertion layer formed of B, Al, Si or the like in addition to Cu is a metal CPP- It is shown to be effective in enhancing the resistance change amount of the GMR film. The difference between the case where Si is inserted into the CCP-GMR film of the present invention and the case where Si is inserted into the metal CPP-GMR film will be described below.

  In the metal CPP-GMR film, the use of the insertion layer increases the MR change rate due to the enhancement of the spin bulk scattering effect. The element most effective in enhancing spin-dependent bulk scattering is Cu, and Si, Al, B, and Mg mentioned in the present invention have a lower enhancement effect than Cu, and Cu is inserted in a metal CPP-GMR film. In this case, the MR change rate can be enhanced most. Specifically, the MR increase amount when Si, B, and Al are inserted into the metal CPP-GMR film is ¼ or less of the MR increase amount when Cu is inserted into the metal CPP-GMR film. .

Also in the CCP-GMR film, the effect of enhancing bulk scattering by inserting the insertion layer is effective. Actually, also in this embodiment, the upper pinned layer 143 is made of Fe ₅₀ Co ₅₀ [1 nm] / Cu [2.5 nm] / Fe ₅₀ Co ₅₀ [1 nm] / Cu [2.5 nm] / Fe ₅₀ Co ₅₀ [1 nm]. By inserting Cu as described above, the enhancement effect of spin-dependent bulk scattering is utilized. However, the MR increase amount of the CCP-GMR film due to the Cu insertion was about 1%, whereas the MR increase amount due to the Si insertion was 1.5% or more. This relationship is completely reversed from the case of insertion into the metal CPP-GMR film. Therefore, it is shown that the cause of MR improvement when Si is inserted into the CCP-GMR film is different from the cause of MR improvement when inserted into the metal CPP-GMR film. It can be seen that a large improvement in MR change rate due to insertion is a peculiar phenomenon in the CCP-GMR film.

  Another reason why the MR improvement effect due to Si insertion into the CCP-GMR film of the present invention is different from the MR improvement effect due to Si insertion into the metal CPP-GMR film is that Si is inserted into the cap layer 19 of the CCP-GMR film. Even in this case, there is an effect of improving MR. Even if Si is inserted into the cap layer of the metal CPP-GMR, the enhancement of the spin-dependent bulk scattering does not occur, so that the MR change rate does not increase at all.

  As described above, even if Si is inserted into the magnetic layer of the metal CPP-GMR film, the reason why the large MR improvement as in the case of inserting Si into the CCP-GMR film is not observed is that the metal CPP-GMR This is probably because the film does not have CCP-NOL as a supply source of surplus oxygen, so there is no surplus oxygen in the magnetic layer, and the full potential of the spin-dependent scattering of the bulk and the interface can be exhibited originally. On the other hand, in the CCP-GMR film, since the full potential of the spin-dependent scattering of the bulk and the interface cannot be exhibited due to the surplus oxygen from the CCP-NOL, the effect of recovering the spin-dependent scattering due to the capture of the surplus oxygen by Si insertion As a result, it is considered that a large MR improvement is caused by a specific effect of trapping excess oxygen by the Si functional layer in the CCP-GMR film.

  In this way, by using the unique effect of capturing excess oxygen by inserting a functional layer made of Si, Mg, B, and Al into the CCP-GMR film, a large effect is obtained on the MR change rate of the CCP-GMR film. be able to.

D. Application of Functional Layer to TMR Film Even if the functional layer of the present invention is applied to a TMR film, an effect of improving MR can be expected.
The TMR film has a structure in which the lower metal layer 15 + current confinement layer 16 + upper metal layer 17 used as the spacer layer of the CCP-GMR film shown in FIG. 1 is replaced with an insulating layer. For the insulating layer of the TMR film, an oxide such as MgO or Al ₂ O ₃ is used. In the TMR film, the spin polarizabilities of the pinned layer 14 and the free layer 18 are used to discuss MR. This spin polarizability is lowered by the diffusion of excess oxygen from MgO or Al ₂ O ₃ to the pinned layer 14 and the free layer 18. Therefore, also in the TMR film, it is effective in improving the MR ratio to suppress the decrease in the spin polarizability due to the diffusion of excess oxygen. That is, even when the functional layer of the present invention is applied to the pinned layer 14, the free layer 18, and the cap layer 19 of the TMR film, an improvement in MR ratio can be expected.

Examples of applying the functional layer of the present invention to the TMR film include the following film configurations.
Ta [5 nm] / Ru [2 nm] / Ir ₂₂ Mn ₇₈ [7 nm] / Co ₈₀ Fe ₂₀ [2 nm] / Ru [0.9 nm] / (Co ₈₀ Fe ₂₀ ) ₈₀ B ₂₀ [2.4 nm] / MgO [ 1.5 nm] / Co ₈₀ Fe ₂₀ [1 nm] / Si [0.25 nm] / Ni ₈₅ Fe ₁₅ [3.5 nm] / Cu [1 nm] / Ta [2 nm] / Ru [1 nm]
The above film configuration is an example in which Si [0.25 nm] is used as a functional layer for the free layer of the TMR film.

Examples of applying the functional layer of the present invention to the TMR film include the following film configurations.
_{Ta [5nm] / Ru [2nm} ] / Ir 22 Mn 78 [7nm] / Co 80 Fe 20 [2nm] / Ru [0.9nm] / (Co 80 Fe 20) 80 B 20 [0.8nm] / Si [ 0.125 nm] / (Co ₈₀ Fe ₂₀ ) ₈₀ B ₂₀ [1.6 nm] / MgO [1.5 nm] / Co ₈₀ Fe ₂₀ [1 nm] / Ni ₈₅ Fe ₁₅ [3.5 nm] / Cu [1 nm] / Ta [2 nm] / Ru [1 nm]
The above film configuration is an example in which Si [0.125 nm] is used as a functional layer for the pinned layer of the TMR film.

Examples of applying the functional layer of the present invention to the TMR film include the following film configurations.
Ta [5 nm] / Ru [2 nm] / Ir ₂₂ Mn ₇₈ [7 nm] / Co ₈₀ Fe ₂₀ [2 nm] / Ru [0.9 nm] / (Co ₈₀ Fe ₂₀ ) ₈₀ B ₂₀ [2.4 nm] / MgO [ 1.5 nm] / Co ₈₀ Fe ₂₀ [1 nm] / Ni ₈₅ Fe ₁₅ [3.5 nm] / Si [0.5 nm] / Cu [0.5 nm] / Ta [2 nm] / Ru [1 nm]
The above film configuration is an example when Si [0.5 nm] is inserted as a functional layer into the cap layer of the TMR film.

In the above, the application example in the case of using MgO as the insulating spacer layer has been shown. If the material used for the insulating spacer layer is a material containing oxygen, an effect of improving MR by inserting a functional layer can be expected. As a specific material for the insulating spacer layer, MgO, Al ₂ O ₃ , or TiO ₂ can be used.

(Apparatus used for manufacturing magnetoresistive effect element)
FIG. 4 is a schematic diagram showing an outline of an example of a film forming apparatus used for manufacturing the magnetoresistive effect element of the present embodiment.

  As shown in FIG. 4, a load lock chamber 51, a pre-cleaning chamber 52, a first metal film forming chamber (MC1) 53, and a second metal film forming chamber (MC2) 54 are centered on a transfer chamber (TC) 50. The oxide layer / nitride layer forming chamber (OC) 60 is provided via a gate valve. In this film forming apparatus, the substrate can be transported in vacuum between the chambers connected via the gate valve, so that the surface of the substrate is kept clean.

  The metal film forming chambers 53 and 54 have multi-targets (5 to 10 yuan). Examples of the film forming method include sputtering methods such as DC magnetron sputtering and RF magnetron sputtering, ion beam sputtering methods, vapor deposition methods, CVD (Chemical Vapor Deposition) methods, and MBE (Molecular Beam Epitaxy) methods.

(Method for producing magnetoresistive film)
Next, an example of the manufacturing method of the magnetoresistive effect element in this embodiment is demonstrated in detail.
FIG. 5 shows a flowchart of the manufacturing process of the magnetoresistive effect element. The basic manufacturing process is as follows. On the substrate (not shown), the lower electrode 11, the base layer 12, the pinning layer 13, the pin layer 14, the lower metal layer 15, the spacer layer 16, the upper metal layer 17, the free layer 18, A cap layer 19 and an upper electrode 20 are sequentially formed. At this time, the substrate is set in the load lock chamber 51, and metal film formation is performed in the metal film formation chambers 53 and 54, and oxidation is performed in the oxide layer / nitride layer formation chamber 60. The ultimate vacuum of the metal film forming chamber is preferably 1 × 10 ⁻⁸ Torr or less, and generally about 5 × 10 ⁻¹⁰ Torr to 5 × 10 ⁻⁹ Torr. The ultimate vacuum of the transfer chamber 50 is on the order of 10 ⁻⁹ Torr. The ultimate vacuum of the oxide layer / nitride layer forming chamber 60 is 8 × 10 ⁻⁸ Torr or less.
Next, the manufacturing process of each layer will be described.

(1) Formation of base layer 12 (step S11)
A lower electrode 11 is previously formed on a substrate (not shown) by a microfabrication process.
On the lower electrode 11, for example, Ta [5 nm] / Ru [2 nm] is formed as the base layer 12. As described above, Ta is the buffer layer 12a for reducing the roughness of the lower electrode. Ru is a seed layer 12b for controlling the crystal orientation and crystal grain size of the spin valve film formed thereon.

(2) Formation of pinning layer 13 (step S12)
A pinning layer 13 is formed on the underlayer 12. As a material of the pinning layer 13, an antiferromagnetic material such as PtMn, PdPtMn, IrMn, RuRhMn can be used.

(3) Formation of pinned layer 14 (and functional layer 21) (step S13)
A pinned layer 14 is formed on the pinning layer 13. The pinned layer 14 can be, for example, a synthetic pinned layer including a lower pinned layer 141 (Co ₉₀ Fe ₁₀ ), a magnetic coupling layer 142 (Ru), and an upper pinned layer 143 (Co ₉₀ Fe ₁₀ [4 nm]). .

Here, for example, the functional layer 21 can be formed by changing the material to be deposited during the deposition of the upper pinned layer 143. Specifically, the functional layer 21 made of Si is formed in the upper pinned layer 143 by switching the film forming material from Co ₉₀ Fe ₁₀ to Si and then returning it to Co ₉₀ Fe ₁₀ again. In addition, when switching from Co ₉₀ Fe ₁₀ to Si and not switching to Co ₉₀ Fe ₁₀ again, the functional layer 21 is formed on the surface of the upper pinned layer 143.

(4) Formation of spacer layers 15 to 17 (step S14)
Next, spacer layers 15 to 17 including the current confinement layer 16 having a current confinement structure (CCP structure) are formed. In order to form the spacer layers 15 to 17, an oxide layer / nitride layer forming chamber 60 is used.

In order to form the current confinement layer 16, the following method is used. Here, a case where a current confinement layer including a current path 162 made of Cu having a metal crystal structure is formed in an insulating layer 161 made of Al ₂ O ₃ having an amorphous structure will be described as an example.

  1) A lower metal layer 15 (for example, Cu) serving as a current path supply source is formed on the upper pinned layer 143 (or the functional layer 21), and then converted to an insulating layer on the lower metal layer 15 A metal layer (for example, AlCu or Al) is formed. Next, pretreatment is performed by irradiating the metal layer to be oxidized with an ion beam of a rare gas (eg, Ar). This pretreatment is called PIT (Pre-ion Treatment). As a result of this PIT, a part of the lower metal layer is sucked and invaded into the metal layer to be oxidized.

2) Oxidizing material is oxidized by supplying an oxidizing gas (for example, O ₂ ). By this oxidation, the metal layer to be oxidized is converted into an insulating layer 161 made of Al ₂ O _3, and a current path 162 penetrating the insulating layer 161 is formed to form the current confinement layer 16. For example, the oxidized metal layer can be oxidized by supplying an oxidizing gas (for example, oxygen) while irradiating an ion beam of a rare gas (Ar, Xe, Kr, He, etc.). This method is called IAO (Ion Assisted Oxidation). By this oxidation treatment, the current confinement layer 16 in a form in which Al ₂ O _{3 as} the insulating layer 161 and Cu as the current path 162 are separated is formed. This is a process that utilizes the difference in oxidation energy that Al is easily oxidized and Cu is not easily oxidized. Next, an upper metal layer 17 (for example, Cu) is formed on the current confinement layer 16.

(5) Formation of free layer 18 (and functional layer 21) (step S15)
On the upper metal layer 17, for example, Co ₉₀ Fe ₁₀ [1 nm] / Ni ₈₃ Fe ₁₇ [3.5 nm] is deposited as the free layer 18. Here, the functional layer 21 can be formed by changing the material to be formed during the formation of the free layer 18. Specifically, the functional layer 21 made of Si is formed in the free layer 18 by switching the film forming material from Co ₉₀ Fe ₁₀ to Si and then to Ni ₈₃ Fe ₁₇ . In addition, when switching from Co ₉₀ Fe ₁₀ to Si and not switching to Ni ₈₃ Fe ₁₇ , the functional layer 21 is formed on the surface of the free layer 18.

(6) Formation of cap layer 19 (and functional layer 23) and upper electrode 20 (step S16)
On the free layer 18, for example, Cu [1 nm] / Ru [10 nm] is laminated as the cap layer 19. Here, the functional layer 22 can be formed by changing the material to be formed during the film formation of the cap layer 19. Specifically, the functional layer 21 made of Si can be formed in the cap layer 19 by switching the film forming material from Cu to Si and then switching to Cu.

  Next, the upper electrode 20 is formed on the cap layer 19 to vertically apply current to the spin valve film.

(Example 1)
Examples of the present invention will be described below. The basic film configuration of the magnetoresistive film according to the embodiment of the present invention is shown below.
・ Lower electrode 11
・ Underlayer 12: Ta [5 nm] / Ru [2 nm]
Pinning layer 13: Ir ₂₂ Mn ₇₈ [7 nm]
Pinned layer 14: Co ₇₅ Fe ₂₅ [3.3 nm] / Ru [0.9 nm] / (Fe ₅₀ Co ₅₀ [1 nm] / Cu [0.25 nm]) × 2 / Fe ₅₀ Co ₅₀ [1 nm]
Lower metal layer 15: Cu [0.6 nm]
Current confinement layer 16: Al ₂ O ₃ insulating layer 161 and Cu current path 162
-Upper metal layer 17: Cu [0.4nm]
Free layer 18: described later Cap layer 19: Cu [1 nm] / Ta [2 nm] / Ru [15 nm]
-Upper electrode 20

  In this example, the characteristics of the magnetoresistive effect film were compared depending on whether or not the functional layer was inserted into the free layer 18. The result of evaluating the characteristics of the free layer structure of Example 1 in which the functional layer is provided in the free layer 18 and the comparative example 1 in which the functional layer is not provided, and the magnetoresistive effect film of Example 1 and Comparative Example 1 are as follows. It is shown below.

The magnetoresistive film of Example 1 was confirmed to have an improvement in MR of 1.5% with respect to Comparative Example 1. This improvement in MR is thought to be because the inserted Si layer captures excess oxygen diffused into the free layer 18 from Al ₂ O ₃ of CCP-NOL. Further, when the magnetoresistive film according to Example 1 was observed with a three-dimensional atom probe, it was confirmed that Si was formed in a layer shape as a functional layer inside the free layer 18.

(Example 2)
In this example, the functional layer was inserted into various portions of the free layer 18 and the cap layer 19 for comparison. The basic film configuration of Example 2 is shown below.
・ Lower electrode 11
・ Underlayer 12: Ta [5 nm] / Ru [2 nm]
Pinning layer 13: Ir ₂₂ Mn ₇₈ [7 nm]
Pinned layer 14: Co ₇₅ Fe ₂₅ [3.9 nm] / Ru [0.9 nm] / (Fe ₅₀ Co ₅₀ [1.8 nm] / Cu [0.25 nm] / Fe ₅₀ Co ₅₀ [1.8 nm]
Metal layer 15: Cu [0.6 nm]
Current confinement layer 16: Al ₂ O ₃ insulating layer 161 and Cu current path 162 Metal layer 17: Cu [0.25 nm]
Metal layer 17: Cu [0.4nm]
Free layer 18: described later Cap layer 19: described later Upper electrode 20

  The basic film configuration of the second embodiment is different from the basic film configuration of the first embodiment in the thickness of the pinned layer 14. By increasing the thickness of the pinned layer 14, the crystallinity of the upper pinned layer 143 is improved, and the spin-dependent bulk scattering effect can be used more effectively, so that a high MR ratio can be obtained. The structures of the free layer 18 and the cap layer 19 produced in this example are shown in Table 3 below. Also in this example, as Comparative Example 2, an element in which no functional layer was inserted was also produced. Table 3 shows the results of evaluating the characteristics of the magnetoresistive films of Examples 2A, 2B, and 2C and Comparative Example 2.

The magnetoresistive films of Example 2A, Example 2B, and Example 2C were all confirmed to have an improvement in MR of 1.5%, 1.3%, and 1.2% with respect to Comparative Example 2, respectively. . This improvement in MR is thought to be because the inserted Si layer captures excess oxygen diffused into the free layer 18 from Al ₂ O ₃ of CCP-NOL. The reason why the MR ratio of Comparative Example 2 is higher than that of Comparative Example 1 is that the film thickness of the pinned layer 14 is larger than that of Comparative Example 1. From this result, it was confirmed that the insertion of the functional layer made of Si into the CCP-GMR film had an MR improvement effect when inserted into the free layer 18 and the cap layer 19. Example 2B and Example 2C have less MR improvement than Example 2A. As a cause of this, in Example 2B and Example 2C, compared with Example 2A, the insertion position of the functional layer is arranged at a position away from the spacer layer. It is thought that the capture of surplus oxygen is inferior compared to Example 2A. When the magnetoresistive effect films according to Examples 2A, 2B, and 2C were observed with a three-dimensional atom probe, it was confirmed that Si was formed as a functional layer inside the free layer 18.

(Example 3)
In this example, a comparison was made when a functional layer was further inserted into the pinned layer 14 of Example 2. The basic film configuration of Example 3 is shown below.
・ Lower electrode 11
・ Underlayer 12: Ta [5 nm] / Ru [2 nm]
Pinning layer 13: Ir ₂₂ Mn ₇₈ [7 nm]
Pin layer 14: described later Lower metal layer 15: Cu [0.6 nm]
Current confinement layer 16: Al ₂ O ₃ insulating layer 161 and Cu current path 162
-Upper metal layer 17: Cu [0.4nm]
Free layer 18: described later Cap layer 19: Cu [1 nm] / Ta [2 nm] / Ru [15 nm]
-Upper electrode 20

  The configurations of the pinned layer 14 and the free layer 18 of Example 3 are shown in the following table. Example 3 is different from Example 2A in that the functional layer Si is inserted into the upper pinned layer 143. The same Table 4 shows the results of evaluating the characteristics of the magnetoresistive film.

  The magnetoresistive film of Example 3 was confirmed to have an improvement in MR of 2.0% with respect to Comparative Example 2. In addition, an MR improvement of 0.5% was confirmed with respect to Example 2A. From the above results, it was confirmed that there was an MR improvement effect when a functional layer made of Si was inserted into the pinned layer 14 of the CCP-GMR film. When the magnetoresistive film according to Example 3 was observed with a three-dimensional atom probe, it was confirmed that Si was formed as a functional layer in the free layer 18 as a functional layer.

Example 4
In this example, a comparison was made when the thickness of the functional layer was changed. The basic film configuration of Example 3 is shown below.
・ Lower electrode 11
・ Underlayer 12: Ta [5 nm] / Ru [2 nm]
Pinning layer 13: Ir ₂₂ Mn ₇₈ [7 nm]
Pinned layer 14: Co ₇₅ Fe ₂₅ [3.9 nm] / Ru [0.9 nm] / (Fe ₅₀ Co ₅₀ [1.8 nm] / Cu [0.25 nm] / Fe ₅₀ Co ₅₀ [1.8 nm]
Lower metal layer 15: Cu [0.6 nm]
Current confinement layer 16: Al ₂ O ₃ insulating layer 161 and Cu current path 162
-Upper metal layer 17: Cu [0.4nm]
Free layer 18: described later Cap layer 19: Cu [1 nm] / Ta [2 nm] / Ru [15 nm]
-Upper electrode 20

  In this example, the characteristics of the magnetoresistive effect film in which the film thickness of the Si layer inserted into the free layer 18 was changed were compared.

The magnetoresistive film of Example 4 has a thicker Si layer than that of Example 1. The magnetoresistive film of Example 4 was confirmed to have an improvement in MR of 1.5% with respect to Comparative Example 2. The amount of increase in MR was equivalent to the amount of increase in MR with respect to Comparative Example 1 in Example 1. Therefore, this improvement in MR is considered to be due to the inserted Si layer capturing excess oxygen diffused into the free layer 18 from Al ₂ O ₃ of CCP-NOL. When the magnetoresistive film according to Example 3 was observed with a three-dimensional atom probe, it was confirmed that Si was formed as a functional layer in the free layer 18 as a functional layer.

(Example 5)
In this example, a comparison was made when Si was inserted into the free layer 18 having a different configuration. The basic film configuration of Example 2 is shown below.
・ Lower electrode 11
・ Underlayer 12: Ta [5 nm] / Ru [2 nm]
Pinning layer 13: Ir ₂₂ Mn ₇₈ [7 nm]
Pinned layer 14: Co ₇₅ Fe ₂₅ [3.9 nm] / Ru [0.9 nm] / (Fe ₅₀ Co ₅₀ [1.8 nm] / Cu [0.25 nm] / Fe ₅₀ Co ₅₀ [1.8 nm]
Lower metal layer 15: Cu [0.6 nm]
Current confinement layer 16: Al ₂ O ₃ insulating layer 161 and Cu current path 162 Metal layer 17: Cu [0.25 nm]
-Upper metal layer 17: Cu [0.4nm]
Free layer 18: described later Cap layer 19: Cu [1 nm] / Ta [2 nm] / Ru [15 nm]
-Upper electrode 20

  The structure of the free layer 18 produced in this example is shown in the following table. Here, Comparative Examples 3, 2, and 4 change the composition of the Fe—Co alloy at the interface of the spacer layer in the free layer 18, and the Fe composition is 50 [at.%], 40 [at.%], 10 [at.%]. Examples 5A, 2A, and 5B have a structure in which Si is inserted into Comparative Examples 3, 2, and 4, respectively. Table 6 shows the results of evaluating the characteristics of the magnetoresistive film of this example. From the following results, a comparison can be made when Si is inserted into different free layer configurations.

The magnetoresistance effect film of Example 5A was confirmed to have an improvement in MR of 2.0% with respect to Comparative Example 3. The magnetoresistive effect film of Example 5B was confirmed to have an MR improvement of 0.5% with respect to Comparative Example 4. This improvement in MR is considered to be due to the capture of the Si layer into which excess oxygen diffused into the free layer 18 from Al ₂ O ₃ of CCP-NOL was captured. Here, comparing the composition of the Fe—Co alloy at the interface of the spacer layer in the free layer 18 with the increase in MR due to Si insertion, the Fe composition is improved by 0.5% at 10 [at.%], And the Fe composition is increased. The improvement is 1.5% at 40 [at.%], And the improvement is 2.2% at 50 [at.%] Fe composition. From this result, it can be seen that when the Fe composition of the Fe—Co alloy disposed on the spacer layer interface side of the free layer 18 is large, the MR improvement due to Si insertion is large.

  A possible cause is the difference in oxidation energy between Fe and Co. From Table 1, Fe has lower oxidation energy than Co and is easily oxidized, so that the free layer having a high Fe composition is more likely to be oxidized by surplus oxygen. That is, the MR degradation amount due to excess oxygen when Si is not inserted is larger in the free layer having a high Fe composition. In such a free layer where the amount of MR degradation due to surplus oxygen is large, it is considered that the amount of MR recovery due to the trapping effect of surplus oxygen due to Si insertion is also large.

  When the magnetoresistive effect films according to Examples 5A and 5B were observed with a three-dimensional atom probe, it was confirmed that Si was formed as a functional layer in the free layer 18 as a functional layer.

(Application of magnetoresistive effect element)
Hereinafter, application of the magnetoresistive effect element (CCP-CPP element) according to the embodiment of the present invention will be described.

In an embodiment of the present invention, the element resistance RA of the CPP element, from the viewpoint of high density corresponding, preferably 500Emuomegamyuemu ² or less, 300Emuomegamyuemu ² or less being more preferred. In calculating the element resistance RA, the resistance R of the CPP element is multiplied by the effective area A of the energized portion of the spin valve film. Here, the element resistance R can be directly measured. On the other hand, since the effective area A of the energized portion of the spin valve film is a value depending on the element structure, it needs to be carefully determined.

For example, when the entire spin valve film is patterned as an effective sensing region, the effective area A is the area of the entire spin valve film. In this case, from the viewpoint of setting the appropriate element resistance, the area of the spin valve film at least 0.04 .mu.m ² below, to 0.02 [mu] m ² or less in the above recording density 200 Gbpsi. However, when the lower electrode 11 or the upper electrode 20 having a smaller area than the spin valve film is formed in contact with the spin valve film, the area of the lower electrode 11 or the upper electrode 20 becomes the effective area A of the spin valve film. When the area of the lower electrode 11 or the upper electrode 20 is different, the area of the smaller electrode is the effective area A of the spin valve film. In this case, from the viewpoint of appropriately setting the element resistance, the area of the smaller electrode is set to at least 0.04 μm ² or less.

  In the embodiment shown in FIGS. 6 and 7 to be described in detail later, the portion where the area of the spin valve film 10 is the smallest in FIG. 6 is the portion in contact with the upper electrode 20, so the width is considered as the track width Tw. Regarding the height direction, the portion in contact with the upper electrode 20 in FIG. 7 is the smallest, so the width is considered as the height length D. The effective area A of the spin valve film is considered as A = Tw × D.

  In the magnetoresistive effect element according to the embodiment of the present invention, the resistance R between the electrodes can be 100Ω or less. This resistance R is, for example, a resistance value measured between two electrode pads of a reproducing head unit attached to the tip of a head gimbal assembly (HGA).

  In the magnetoresistive effect element according to the embodiment of the present invention, when the pinned layer 14 or the free layer 18 has an fcc structure, it is desirable to have fcc (111) orientation. When the pinned layer 14 or the free layer 18 has a bcc structure, it is desirable to have bcc (110) orientation. When the pinned layer 14 or the free layer 18 has an hcp structure, it is desirable to have hcp (001) orientation or hcp (110) orientation.

  The crystal orientation of the magnetoresistive effect element according to the embodiment of the present invention is preferably 4.0 degrees or less, more preferably 3.5 degrees or less, and further preferably 3.0 degrees or less in terms of the orientation variation angle. This is calculated | required as a half value width of the rocking curve in the peak position obtained by (theta) -2 (theta) measurement of X-ray diffraction. Further, it can be detected as a dispersion angle of the spot at the nano-diffraction spot from the element cross section.

  Although depending on the material of the antiferromagnetic film, since the lattice spacing is generally different between the antiferromagnetic film and the pinned layer 14 / spacer layer 16 / free layer 18, the orientation variation angle in each layer is different. Can be calculated. For example, platinum manganese (PtMn) and pinned layer 14 / spacer layer 16 / free layer 18 often have different lattice spacings. Since platinum manganese (PtMn) is a relatively thick film, it is a suitable material for measuring variation in crystal orientation. Regarding the pinned layer 14 / spacer layer 16 / free layer 18, the pinned layer 14 and the free layer 18 may have different crystal structures such as a bcc structure and an fcc structure. In this case, the pinned layer 14 and the free layer 18 have different crystal orientation dispersion angles.

(Magnetic head)
6 and 7 show a state in which the magnetoresistive effect element according to the embodiment of the present invention is incorporated in a magnetic head. FIG. 6 is a cross-sectional view of the magnetoresistive element cut in a direction substantially parallel to a medium facing surface facing a magnetic recording medium (not shown). FIG. 7 is a cross-sectional view of the magnetoresistive element cut in a direction perpendicular to the medium facing surface ABS.

  The magnetic head illustrated in FIGS. 6 and 7 has a so-called hard abutted structure. The magnetoresistive film 10 is the CCP-CPP film described above. A lower electrode 11 and an upper electrode 20 are provided above and below the magnetoresistive effect film 10, respectively. In FIG. 6, a bias magnetic field application film 41 and an insulating film 42 are laminated on both sides of the magnetoresistive film 10. As shown in FIG. 7, a protective layer 43 is provided on the medium facing surface of the magnetoresistive film 10.

  The sense current for the magnetoresistive effect film 10 is energized in a direction substantially perpendicular to the film surface as indicated by the arrow A by the lower electrode 11 and the upper electrode 20 arranged above and below the magnetoresistive effect film 10. A bias magnetic field is applied to the magnetoresistive film 10 by a pair of bias magnetic field application films 41, 41 provided on the left and right. By this bias magnetic field, the magnetic anisotropy of the free layer 18 of the magnetoresistive effect film 10 is controlled to form a single magnetic domain, thereby stabilizing the magnetic domain structure and suppressing Barkhausen noise due to the domain wall movement. can do. Since the S / N ratio of the magnetoresistive film 10 is improved, high sensitivity magnetic reproduction is possible when applied to a magnetic head.

(Hard disk and head gimbal assembly)
The magnetic head shown in FIGS. 6 and 7 can be incorporated into a recording / reproducing integrated magnetic head assembly and mounted on a magnetic recording / reproducing apparatus.

  FIG. 8 is a main part perspective view illustrating a schematic configuration of such a magnetic recording / reproducing apparatus. That is, the magnetic recording / reproducing apparatus 150 of this embodiment is an apparatus of a type using a rotary actuator. In the figure, a magnetic disk 200 is mounted on a spindle 152 and rotated in the direction of arrow A by a motor (not shown) that responds to a control signal from a drive device control unit (not shown). The magnetic recording / reproducing apparatus 150 of this embodiment may include a plurality of magnetic disks 200.

  A head slider 153 that records and reproduces information stored in the magnetic disk 200 is attached to the tip of a thin-film suspension 154. The head slider 153 has a magnetic head including the magnetoresistive effect element according to any one of the above-described embodiments mounted near its tip.

  When the magnetic disk 200 rotates, the medium facing surface (ABS) of the head slider 153 is held with a predetermined flying height from the surface of the magnetic disk 200. Alternatively, a so-called “contact traveling type” in which the slider contacts the magnetic disk 200 may be used.

  The suspension 154 is connected to one end of the actuator arm 155. A voice coil motor 156, which is a kind of linear motor, is provided at the other end of the actuator arm 155. The voice coil motor 156 includes a drive coil (not shown) wound around a bobbin portion, and a magnetic circuit including a permanent magnet and a counter yoke arranged so as to sandwich the coil.

  The actuator arm 155 is held by ball bearings (not shown) provided at two positions above and below the spindle 157, and can be freely rotated and slid by a voice coil motor 156.

  FIG. 9 is an enlarged perspective view of the head gimbal assembly ahead of the actuator arm 155 as viewed from the disk side. That is, the assembly 160 has an actuator arm 155, and a suspension 154 is connected to one end of the actuator arm 155. A head slider 153 including a magnetic head including the magnetoresistive effect element according to any one of the above-described embodiments is attached to the tip of the suspension 154. The suspension 154 has a lead wire 164 for writing and reading signals, and the lead wire 164 and each electrode of the magnetic head incorporated in the head slider 153 are electrically connected. In the figure, reference numeral 165 denotes an electrode pad of the assembly 160.

  According to the present embodiment, by providing the magnetic head including the magnetoresistive element described above, it is possible to reliably read information magnetically recorded on the magnetic disk 200 at a high recording density.

(Magnetic memory)
Next, a magnetic memory equipped with the magnetoresistive effect element according to the embodiment of the present invention will be described. That is, by using the magnetoresistive effect element according to the embodiment of the present invention, a magnetic memory such as a random access magnetic memory (MRAM) in which memory cells are arranged in a matrix can be realized.

  FIG. 10 is a diagram showing an example of a matrix configuration of the magnetic memory according to the embodiment of the present invention. This figure shows a circuit configuration when memory cells are arranged in an array. In order to select one bit in the array, a column decoder 350 and a row decoder 351 are provided, and the switching transistor 330 is turned on by the bit line 334 and the word line 332 to be uniquely selected and detected by the sense amplifier 352. As a result, the bit information recorded in the magnetic recording layer (free layer) in the magnetoresistive film 10 can be read. When writing bit information, a magnetic field generated by applying a write current to a specific write word line 332 and bit line 334 is applied.

  FIG. 11 is a diagram showing another example of the matrix configuration of the magnetic memory according to the embodiment of the present invention. In this case, bit lines 322 and word lines 334 wired in a matrix are selected by decoders 360 and 361, respectively, and specific memory cells in the array are selected. Each memory cell has a structure in which a magnetoresistive element 10 and a diode D are connected in series. Here, the diode D has a role of preventing the sense current from bypassing in the memory cells other than the selected magnetoresistive effect element 10. Writing is performed by a magnetic field generated by supplying a write current to the specific bit line 322 and the write word line 323, respectively.

  FIG. 12 is a cross-sectional view showing the main part of the magnetic memory according to the embodiment of the present invention. FIG. 13 is a cross-sectional view taken along the line A-A ′ of FIG. 12. The structures shown in these drawings correspond to 1-bit memory cells included in the magnetic memory shown in FIG. This memory cell has a memory element portion 311 and an address selection transistor portion 312. The memory element portion 311 includes the magnetoresistive effect element 10 and a pair of wirings 322 and 324 connected thereto. The magnetoresistive effect element 10 is the magnetoresistive effect element (CCP-CPP element) according to the above-described embodiment.

  On the other hand, the address selection transistor portion 312 is provided with a transistor 330 connected via a via 326 and a buried wiring 328. The transistor 330 performs a switching operation according to the voltage applied to the gate 332, and controls opening and closing of a current path between the magnetoresistive effect element 10 and the wiring 334. Further, below the magnetoresistive effect element 10, a write wiring 323 is provided in a direction substantially orthogonal to the wiring 322. These write wirings 322 and 323 can be formed of, for example, aluminum (Al), copper (Cu), tungsten (W), tantalum (Ta), or an alloy containing any of these.

  In the memory cell having such a configuration, when writing bit information to the magnetoresistive effect element 10, a write pulse current is supplied to the wirings 322 and 323, and a composite magnetic field induced by these currents is applied to thereby apply the magnetoresistive effect element. The magnetization of the recording layer is appropriately reversed. When reading bit information, a sense current is passed through the wiring 322, the magnetoresistive effect element 10 including the magnetic recording layer, and the lower electrode 324, and the resistance value of the magnetoresistive effect element 10 or a change in the resistance value is measured. To do.

  The magnetic memory according to the embodiment of the present invention uses the magnetoresistive effect element (CCP-CPP element) according to the embodiment described above to reliably control the magnetic domain of the recording layer even if the cell size is reduced. Reliable writing can be ensured and reading can be performed reliably.

(Other embodiments)
Embodiments of the present invention are not limited to the above-described embodiments, and can be expanded and modified. The expanded and modified embodiments are also included in the technical scope of the present invention. The specific structure of the magnetoresistive film, and other shapes and materials of the electrode, bias application film, insulating film, etc., are appropriately implemented by those skilled in the art, and the present invention is similarly implemented. The effect of can be obtained.

  For example, when applying a magnetoresistive element to a reproducing magnetic head, the detection resolution of the magnetic head can be defined by providing magnetic shields above and below the element.

  The embodiment of the present invention can be applied not only to a longitudinal magnetic recording system but also to a perpendicular magnetic recording system magnetic head or magnetic reproducing apparatus. Furthermore, the magnetic reproducing apparatus of the present invention may be a so-called fixed type having a specific recording medium constantly provided, or a so-called “removable” type in which the recording medium can be replaced.

  In addition, all magnetoresistive elements, magnetic heads, magnetic storage / reproduction devices, and magnetic memories that can be appropriately designed and implemented by those skilled in the art based on the magnetic head and magnetic storage / reproduction device described above as embodiments of the present invention Are also within the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Magnetoresistance effect film | membrane 11 Lower electrode 12 Underlayer 13 Pinning layer 14 Pin layer 15 Lower (nonmagnetic) metal layer 16 Current confinement layer 17 Upper (nonmagnetic) metal layer 18 Free layer 19 Cap layer 20 Upper electrode 21 Functional layer 150 Magnetic recording / reproducing apparatus 152 Spindle 153 Head slider 154 Suspension 155 Actuator arm 156 Voice coil motor 157 Spindle 160 Magnetic head assembly 164 Lead wire 200 Magnetic recording magnetic disk 311 Storage element portion 312 Address selection transistor portion 312 Selection transistor portion 321 Magnetoresistance Effect element 322 Bit line 322 Wiring 323 Word line 323 Wiring 324 Lower electrode 326 Via 328 Wiring 330 Switching transistor 332 Gate 332 Word line 334 Bit line 33 4 Word line 350 Column decoder 351 Row decoder 352 Sense amplifier 360 Decoder

Claims (18)

A first electrode;
A second electrode;
An antiferromagnetic layer provided between the first electrode and the second electrode;
A magnetization pinned layer provided between the second electrode and the antiferromagnetic layer and having magnetization substantially pinned in one direction;
A spacer layer provided between the second electrode and the magnetization pinned layer and including an insulating layer having an oxide and a current confinement layer having a conductor through which current flows through the insulating layer in a layer direction;
A magnetization free layer provided between the second electrode and the spacer layer, the magnetization of which changes with respect to an external magnetic field;
A thin film layer provided between the second electrode and the magnetization free layer;
Layers of pre Symbol magnetization free layer, and the provided at least one portion of the interface of the free layer and the spacer layer, Si, Mg, and is selected from B oxide formation free energy one lower than Fe A functional layer composed of elements;
A magnetoresistive effect element comprising: The magnetoresistive effect element according to claim 1 , wherein the functional layer contains Si. Wherein the film thickness of the functional layer is 0.1nm or 10nm or less, magnetoresistance effect element according to claim 1 or 2. The spacer layer, said current confinement layer, said characterized in that it comprises at least one metal layer formed so as to be adjacent magnetization pinned layer and the magnetization free layer, any one of claims 1 to 3 The magnetoresistive effect element described in 1. The magnetoresistive effect element according to claim 4 , wherein the metal layer includes any one of Cu, Ag, and Au. The magnetoresistive effect element according to any one of claims 1 to 5 , wherein the conductor constituting the current confinement layer contains Cu, Ag, or Au as a main component. Wherein at least one of the magnetization pinned layer and the magnetization free layer is characterized by containing Fe, magnetoresistance effect element according to any one of claims 1 to 6. Fe content of 10 [at.%] Or more in at least one of the magnetization pinned layer in the region within 1 nm from the interface of the spacer layer and the region in the magnetization free layer within 1 nm from the interface of the spacer layer The magnetoresistive effect element according to claim 7 , wherein: Fe content is 40 [at.%] Or more in at least one of the magnetization pinned layer within 1 nm from the spacer layer interface and the magnetization free layer within 1 nm from the spacer layer interface. The magnetoresistive effect element according to claim 8 , wherein: A first electrode;
A second electrode;
An antiferromagnetic layer provided between the first electrode and the second electrode;
A magnetization pinned layer provided between the second electrode and the antiferromagnetic layer and having magnetization substantially pinned in one direction;
An insulating spacer layer provided between the second electrode and the magnetization pinned layer, having an oxide and through which a tunnel current passes;
A magnetization free layer provided between the second electrode and the insulating spacer layer, the magnetization of which changes with respect to an external magnetic field;
A thin film layer provided between the second electrode and the magnetization free layer;
Layers of pre Symbol magnetization free layer, and the provided at least one portion of the interface of the free layer and the spacer layer, Si, Mg, and is selected from B oxide formation free energy one lower than Fe A functional layer composed of elements;
A magnetoresistive effect element comprising: The magnetoresistive effect element according to claim 10 , wherein the functional layer contains Si. The magnetoresistive effect element according to claim 10 or 11 , wherein the functional layer has a thickness of 0.1 nm or more and 10 nm or less. The magnetoresistive effect element according to any one of claims 10 to 12 , wherein at least one of the magnetization pinned layer and the magnetization free layer contains Fe. In at least one of the region of the magnetization pinned layer within 1 nm from the interface of the insulating spacer layer and the region of the magnetization free layer within 1 nm from the interface of the insulating spacer layer, the Fe content is 10 [at.%]. The magnetoresistive effect element according to claim 13 , wherein Fe content is 40 [at.%] Or more in at least one of the magnetization pinned layer within 1 nm from the spacer layer interface and the magnetization free layer within 1 nm from the spacer layer interface. The magnetoresistive effect element according to claim 14 , wherein: Magnetic head is characterized in that it comprises a magnetoresistive device according to any one of claims 1 to 15 A magnetic recording / reproducing apparatus comprising a magnetic recording medium and the magnetic head according to claim 16 . Magnetic memory, characterized by comprising a magnetoresistance effect element according to any one of claims 1 to 15.

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