JP2010016408A - Magnetoresistive element and magnetic memory - Google Patents

Abstract

The present invention has a high magnetoresistance ratio and reduces a write current.
A magnetoresistive element includes a pinned layer having a magnetic anisotropy perpendicular to a film surface and having a pinned magnetization direction, and magnetic layers and nonmagnetic layers alternately laminated. A nonmagnetic material having a structure and having a magnetic anisotropy perpendicular to the film surface and having a changeable magnetization direction, and is provided between the fixed layer 15 and the recording layer 17. And an intermediate layer 16 made of. Of the magnetic layers constituting the recording layer 17, the magnetic layer 17A-1 in contact with the intermediate layer 16 is made of an alloy containing cobalt (Co) and iron (Fe), and the film thickness is not in contact with the intermediate layer 16. Greater than layer thickness.
[Selection] Figure 6

Description

  The present invention relates to a magnetoresistive element and a magnetic memory, and more particularly, to a magnetoresistive element capable of recording information by supplying current bidirectionally and a magnetic memory using the same.

  The magnetoresistive effect is applied to a hard disk drive (HDD), which is a magnetic storage device, and is currently in practical use. The magnetic head mounted on the HDD uses the GMR (Giant Magnetoresistive) effect or the TMR (Tunneling Magnetoresistive) effect, both of which utilize the resistance change that occurs when the magnetization directions of the two magnetic layers form an angle with each other. The magnetic field from the magnetic medium is detected.

  In recent years, various techniques have been proposed in order to realize a magnetic random access memory (MRAM) using a GMR element or a TMR element. As an example, there is a format in which “1” and “0” information is recorded according to the magnetization state of an MTJ (Magnetic Tunnel Junction) element, and this information is read out by resistance change due to the TMR effect. In this type of MRAM, a number of techniques have been proposed for practical use. Furthermore, the magnetization reversal due to the spin-polarized current is theoretically expected and confirmed by experiments, and an MRAM using the spin-polarized current has been proposed. According to this method, the magnetization reversal of the magnetic layer can be realized only by passing a spin-polarized current through the magnetic layer, and if the volume of the magnetic layer is small, fewer spin-polarized electrons are injected. It is expected to be compatible. However, the problem of thermal disturbance becomes obvious as miniaturization occurs.

  In order to ensure thermal disturbance resistance, it is necessary to increase the magnetic anisotropy energy density. In the in-plane magnetization type configuration mainly studied so far, it is common to use shape magnetic anisotropy. In this case, since the magnetic anisotropy is ensured by using the shape, the reversal current becomes sensitive to the shape, and there is a problem that the variation in reversal current increases with miniaturization. To increase the magnetic anisotropy energy density using shape magnetic anisotropy, it is considered to increase the aspect ratio of the MTJ element, increase the thickness of the magnetic layer, or increase the saturation magnetization of the magnetic layer. It is done.

  An increase in the aspect ratio of the MTJ element increases the cell area and is not suitable for increasing the capacity. An increase in the film thickness and saturation magnetization of the magnetic material is undesirable because it results in an increase in the current value necessary for magnetization reversal due to the spin-polarized current. When using magnetocrystalline anisotropy instead of shape magnetic anisotropy in the in-plane magnetization configuration, a material having a large magnetocrystalline anisotropy energy density (for example, Co-- When a Cr alloy material is used, the crystal axes are greatly dispersed in the plane, so that MR (Magnetoresistance) decreases or incoherent precession is induced, resulting in an increase in reversal current. .

  On the other hand, when the magnetocrystalline anisotropy is used in the perpendicular magnetization type configuration, it is possible to suppress the dispersion of the crystal axes, which is a problem in the in-plane magnetization type. For example, the crystal structure of the Co—Cr alloy material described above is a hexagonal crystal structure and has a uniaxial magnetocrystalline anisotropy with the c axis as the easy axis, so the crystal orientation is parallel to the direction perpendicular to the film surface. Control may be performed so that In the case of the in-plane magnetization type, it is necessary to align the c-axis with a single axis in the film surface, and the rotation of each crystal grain in the film surface becomes the rotation of the crystal axis and disperses the uniaxial direction. In the case of the perpendicular magnetization type, since the c-axis is in the direction perpendicular to the film surface, even if each crystal grain rotates in the film surface, the c-axis remains vertical and does not disperse.

Similarly, by controlling the c-axis in the vertical direction even in the tetragonal structure, it is possible to realize a perpendicular magnetization type MTJ configuration. Magnetic material tetragonal structure, for example, L1 ₀ type Fe-Pt ordered alloy having a crystal structure, Fe-Pd ordered alloy, Co-Pt ordered alloy, Fe-Co-Pt ordered alloy, Fe-Ni-Pt Rules An alloy, an Fe-Ni-Pd ordered alloy, etc. are mentioned. However, in order to make the L1 ₀ structure a perpendicular magnetization film, it is necessary to orient its crystal orientation to the (001) plane, and therefore an underlayer for controlling the crystal orientation and heat for ordering. It is necessary to develop the process in accordance with the magnetization reversal method using the spin-polarized current.

  On the other hand, it is conceivable to realize perpendicular magnetic anisotropy by utilizing magnetic anisotropy at the interface. As the perpendicular magnetization film using the magnetic anisotropy of the interface, for example, there is a so-called artificial lattice in which a magnetic layer and a nonmagnetic layer are repeatedly laminated. Also in this case, it is possible to suppress the dispersion of crystal axes, which was a problem with the in-plane magnetization type. In the case of a magnetic material composed of an artificial lattice, since the perpendicular magnetic anisotropy does not mainly include the magnetocrystalline anisotropy unlike an Fe—Pt ordered alloy or the like, the crystal orientation is comparatively hardly restricted. As a perpendicular magnetic anisotropic material of an artificial lattice, a system in which a magnetic layer is Co and a nonmagnetic layer is Pt and these are alternately stacked is well known.

  In consideration of the magnetization reversal method using the spin-polarized current, the recording layer material preferably has a smaller damping constant. However, when Pt is present as a nonmagnetic layer at the interface of the magnetic layer, there is a problem that the damping constant increases due to the spin pumping effect. In addition, in the artificial lattice, it is preferable that the magnetic layer is thinned to about 0.3 to 1.0 nm from the viewpoint of magnetic anisotropy energy density, but when the magnetic layer is thinned, the spin pumping effect becomes more remarkable. Since it works, there is a problem that the damping constant becomes large.

  To increase the capacity of the MRAM, a high magnetoresistance ratio is necessary from the viewpoint of reading. In recent years, there are many reports of MTJ using MgO as a barrier material exhibiting a high magnetoresistance ratio, and in order to realize a high magnetoresistance ratio, it is important that the (100) plane of MgO is oriented. . It is known that when CoFeB having a microcrystalline structure or an amorphous structure is formed on both interface sides of MgO as a magnetic layer, it is oriented in the (100) plane. There has been no report of using CoFeB as a magnetic layer in an artificial lattice, and CoFeB having no clear crystal structure is expected to have a significantly reduced perpendicular magnetic anisotropy compared to Co having a crystal structure.

  When the magnetization of the recording layer having perpendicular magnetic anisotropy is reversed by the spin injection method, the aspect ratio of the spin injection element may be 1, which is suitable for miniaturization. Therefore, if the magnetization reversal by the spin-polarized current can be realized by a perpendicular magnetization type spin injection device, it is possible to simultaneously satisfy the reduction of the write current, the resistance to the bit information thermal disturbance, and the reduction of the cell area. However, in order to form a spin injection device using an artificial lattice as a recording layer material, as described above, an increase in the damping constant due to the spin pumping effect and a high TMR are problems. A report example and a specific method of a spin injection device that uses an artificial lattice as a recording layer material and realizes a high damping ratio and a high magnetoresistance ratio have not been proposed so far.

  The present invention provides a magnetoresistive element and a magnetic memory having a high magnetoresistance ratio and capable of reducing a write current.

  A magnetoresistive element according to a first aspect of the present invention includes a first fixed layer having a magnetic anisotropy perpendicular to a film surface and having a fixed magnetization direction, and a magnetic layer and a nonmagnetic layer. Between a recording layer having a laminated structure in which layers are alternately laminated, having magnetic anisotropy perpendicular to the film surface, and capable of changing the magnetization direction, and the first fixed layer and the recording layer And a first intermediate layer made of a nonmagnetic material. Of the magnetic layers constituting the recording layer, the first magnetic layer in contact with the first intermediate layer is made of an alloy containing cobalt (Co) and iron (Fe), and the film thickness thereof is the first intermediate layer. It is larger than the thickness of the magnetic layer not in contact with the layer.

  A magnetic memory according to a second aspect of the present invention is provided with the magnetoresistive element according to the first aspect and the first and the first elements provided so as to sandwich the magnetoresistive element and energizing the magnetoresistive element. And a memory cell including a second electrode.

  According to the present invention, it is possible to provide a magnetoresistive element and a magnetic memory that have a high magnetoresistance ratio and can reduce a write current.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, elements having the same function and configuration are denoted by the same reference numerals, and redundant description will be given only when necessary.

[First Embodiment]
[1] Artificial lattice as a recording layer material When an artificial lattice is used as a recording layer constituting a spin injection type magnetoresistive element, ensuring perpendicular magnetic anisotropy, reducing a damping constant, and a high magnetoresistance ratio (MR ratio) Must be compatible at the same time. Known examples of using an artificial lattice as a recording layer include Patent Document 1: US2005 / 0185455A1, Patent Document 2: US2005 / 0104101A1. Patent Document 1 discloses Pt as a nonmagnetic layer constituting an artificial lattice, and this is expected to increase the damping constant. Patent Document 2 discloses Co / Pt, Co / Au, and Ni / Cu as artificial lattices, but can ensure all of perpendicular magnetic anisotropy, reduction of damping constant, and high MR ratio. No specific means are disclosed. As will be described later, the above condition cannot be satisfied only by stacking Co / Au.

  The inventors first considered the material of the nonmagnetic layer in order to realize a low damping constant in the form of an artificial lattice in which magnetic layers and nonmagnetic layers are alternately laminated. Platinum (Pt) and palladium (Pd) are generally known as nonmagnetic materials for realizing an artificial lattice having perpendicular magnetic anisotropy. However, the degree of increase in the damping constant due to the spin pumping effect is remarkably large in Pt, and is further increased by making the magnetic layer constituting the artificial lattice thin. Therefore, when considering magnetization reversal by spin injection, it is not preferable to use Pt from the viewpoint of the damping constant. Pd does not increase the damping constant more than Pt, but the magnetic material constituting the artificial lattice must be appropriately selected as will be described later.

  As candidates for nonmagnetic materials other than Pd, the inventors focused on copper (Cu), silver (Ag), and gold (Au), which have a low spin scattering effect. When an artificial lattice was formed using Co as a magnetic layer using these nonmagnetic materials, Cu and Ag became in-plane magnetization films, but Au became a perpendicular magnetization film and exhibited perpendicular magnetic anisotropy. It could be confirmed. Therefore, from the viewpoint of reducing the damping constant and ensuring the perpendicular magnetic anisotropy, it is preferable to select a material mainly composed of palladium (Pd) or gold (Au) as the nonmagnetic material.

  Next, the magnetic material constituting the artificial lattice was examined. An artificial lattice was formed using Pd as the nonmagnetic material, and the perpendicular magnetic anisotropy energy density and the composition dependence of the Co—Fe alloy were measured. As the amount of iron (Fe) increased, the perpendicular magnetic anisotropy decreased. I found out that On the other hand, considering the Co—Fe alloy from the viewpoint of the damping constant, it is known that the damping constant decreases as the Fe concentration increases.

  The inventors have assumed that palladium (Pd) and gold (Au), which are nonmagnetic materials that newly form artificial lattices, are assumed to be a laminate of Au / Co—Fe / Au and Pd / Co—Fe / Pd. Each film was formed, and the dependence of the damping constant on the composition of the Co—Fe alloy and the dependence of the damping constant on the film thickness were examined. In the description of the laminated film, the left side of “/” represents the upper layer, and the right side represents the lower layer (substrate side).

  As a result, it has been found that the dependency of the composition of the Co—Fe alloy varies greatly depending on the thickness of the Co—Fe alloy (see FIG. 1). It can be seen that when the film thickness of the Co—Fe alloy is about 3 nm, the damping constant is the smallest when the Fe concentration is in the vicinity of 20 at% when both the nonmagnetic materials are Pd and Au. Note that “at%” represents atomic (number) percent. When the film thickness of the Co—Fe alloy is reduced to about 1 nm, when the nonmagnetic material is Pd, the damping constant is minimized when the Co concentration is around 80 at% (that is, the Fe concentration is 20 at%). There is no significant difference compared to the case where the concentration is 50 at%.

  When the nonmagnetic material is Au, the damping constant is smaller when the Fe concentration is 50 at% than when 20 at%. In other words, the damping constant is small near the Co concentration of 80 at% (that is, the Fe concentration is 20 at%), but when the Co—Fe alloy is thinned, the Fe concentration is 50 at% and the damping constant depends on the film thickness. Because of the looseness of the properties, the damping constants of Fe at 20 at% and 50 at% are almost the same at a certain film thickness, and when the film thickness is further reduced, the damping constant tends to be smaller at Fe 50 at%.

  When Fe is 0 at%, that is, when Co is 100 at%, the film thickness dependence of the damping constant is remarkable. From the viewpoint of reducing the damping constant, an artificial lattice in which the magnetic material is cobalt (Co) is recorded by the spin injection method. It is not preferable to use it as a layer material. Therefore, in order to reduce the damping constant while maintaining the perpendicular magnetic anisotropy, an artificial lattice is formed by using a Co—Fe alloy containing Fe at 20 at% or more (that is, Co 80% or less) as a magnetic material. It is preferable to form. As is clear from FIG. 1, if the film thickness is the same, Au is more preferable than Pd as a nonmagnetic material from the viewpoint of the damping constant.

Therefore, a Pd—Au alloy was examined as a nonmagnetic material for forming an artificial lattice. FIG. 2 shows the dependency of the damping constant on the composition of the Pd—Au alloy in the stacked structure of Pd—Au / Co ₈₀ Fe ₂₀ / Pd—Au. However, the film thickness of Co ₈₀ Fe ₂₀ is about 3 nm. As can be seen from FIG. 2, the damping constant can be reduced by increasing the Au concentration relative to Pd. Therefore, when a Pd—Au alloy is used as the nonmagnetic material for forming the artificial lattice, it is preferable that 50 at% or more of Au is included from the viewpoint of only the damping constant.

Next, the magnitude of perpendicular magnetic anisotropy was examined in an artificial lattice using a Pd—Au alloy as a nonmagnetic material. On the thermal oxidation substrate, Ta having a thickness of about 5 nm, Ru having a thickness of about 10 nm, Pd having a thickness of about 1 nm, Au having a thickness of about 4 nm, [Co ₈₀ Fe ₂₀ 0.5 nm / Pd-Au 1 nm] The dependence of the magnetic anisotropy energy density on the composition of the Pd—Au alloy was measured using a laminated structure in which Co ₈₀ Fe _{20 having} a thickness of about 0.5 nm and Au having a thickness of about 3 nm were sequentially formed. The results are shown in FIG.

  As can be seen from FIG. 3, the anisotropic energy density tends to be saturated when Pd is about 50 at%. From this result, from the viewpoint of damping constant and perpendicular magnetic anisotropy, when a Pd—Au alloy is used as a nonmagnetic material, the composition of Au is most preferably about 50 at%. A particularly excellent effect can be obtained in the range where the Au composition is 45 at% or more and 55 at% or less. When this nonmagnetic material is applied to the nonmagnetic layer of the recording layer, it is possible to significantly reduce the damping constant while maintaining the perpendicular magnetic anisotropy.

  Of the magnetic layers forming an artificial lattice as the recording layer, the damping constant of the first magnetic layer in contact with the first intermediate layer is preferably particularly small. Since the first magnetic layer is in contact with the first intermediate layer, spin-polarized electrons flow first and are susceptible to spin torque. When the first magnetic layer is made of Co—Fe or Co—Fe—B, the Co—Fe composition is as described above. However, in view of the spin pumping effect, the thickness of the first magnetic layer is vertical. A thicker one within the range where the magnetization can be maintained is preferable because the damping constant can be reduced.

Furthermore, as a magnetic material having a small damping constant, a magnetic material having a composition of Co ₂ XY can be used as the first magnetic layer. Here, X is one or more elements of vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), and copper (Cu), and Y is aluminum (Al ), Gallium (Ga), indium (In), silicon (Si), germanium (Ge), tin (Sn), and antimony (Sb). Alloys of these compositions exhibit an L2 ₁ structure when they form ordered alloys. The structure in which the X and Y irregularly substitutions are B2 structure, is the polarization ratio is small compared to the L2 ₁ structure. When Co, X, and Y are substituted irregularly, an A2 structure (body-centered cubic structure) is obtained. The first magnetic layer is preferably an L2 ₁ structure or a B2 structure from the viewpoint of a damping constant and a polarizability.

  Usually, in a GMR (Giant Magnetoresistive) film, copper (Cu) is often used as a spacer material (intermediate layer). However, from the results of FIG. 3, when forming a perpendicular magnetization type GMR element, it is easier to ensure perpendicular magnetic anisotropy when using gold (Au) as a spacer material than copper (Cu). I understood. As described above, when using cobalt (Co) as a magnetic material and copper (Cu), silver (Ag), and gold (Au) as nonmagnetic materials, an artificial lattice is formed, respectively. It can also be seen from the fact that Au showed perpendicular magnetic anisotropy.

  Therefore, a spin injection type GMR element having a layer structure as shown in FIG. 4 was formed. The layer structure of FIG. 4 is on the Si substrate 11 with a thermal oxide film, Ta / Cu / Ta as the low resistance layer 12, Ta about 5 nm thick as the adhesion layer 13 with the low resistance layer 12, and the adhesion layer 13 Ru of about 10 nm thickness as the underlayer 14, Pd of about 1 nm thickness of Pd and Co of about 0.3 nm thickness of 8 are stacked as the fixed layer 15, and the magnetic layer Co of the ninth cycle is about 2 nm thick. The artificial lattice Co 2 nm / Pd 1 nm / [Co 0.3 nm / Pd 1 nm] 8, Au having a thickness of about 4 nm as the spacer layer 16, Co having a thickness of about 0.5 nm and Pd having a thickness of about 1 nm as the recording layer 17 As the protective layer 18, Au1 nm / Co0.5 nm / Pd1 nm / Co0.5 nm with the nonmagnetic layer (the uppermost layer) in contact with the magnetic layer farthest from the spacer layer 16 from the laminated artificial lattice being Au1 nm It is successively formed with the structure of thickness 5nm approximately Ru. On the hard mask 19 necessary for element processing, Ru having a film thickness of about 35 nm and Ta having a film thickness of about 60 nm were sequentially formed.

FIG. 5 shows an MR-H curve of a GMR element processed to an element diameter of 80 nm. In FIG. 5, the vertical axis represents the MR ratio (%), and the horizontal axis represents the magnetic field H (Oe). As shown in FIG. 5, the GMR element shows a clear coercive force difference type loop. On the other hand, when the IH phase diagram was created and the reversal current was evaluated, the reversal current density in which the magnetization arrangement of the fixed layer 15 and the recording layer 17 changed from anti-parallel to parallel. Was 120 MA / cm ² , and the inversion current density from parallel to antiparallel was 120 MA / cm ² . However, the coercive force when no current was applied was 2.4 kOe from the IH phase diagram.

On the other hand, when the nonmagnetic layer of the recording layer 17 is made of Au 1 nm / Co 0.5 nm / Au 1 nm / Co 0.5 nm in which Pd 1 nm is changed to Au 1 nm, the reversal current density from the antiparallel to the parallel is 4. 8MA / cm ^2, the inversion current density to anti-parallel from the parallel was 4.4mA / cm ^2. However, from the IH phase diagram, the coercive force when no current was applied was 130 Oe. As expected from the damping constant, the current density normalized by the coercive force is lower when all the nonmagnetic layers are made of Au.

In addition, when the magnetic layer of the recording layer 17 is changed from Co to Co ₈₀ Fe ₂₀ , the structure is Au 1 nm / Co ₈₀ Fe ₂₀ 0.5 nm / Pd 1 nm / Co ₈₀ Fe ₂₀ 0.5 nm, and the magnetization arrangement is antiparallel to parallel. The reversal current density to 2.7 was MA / cm ² , and the reversal current density from parallel to antiparallel was 6.1 MA / cm ² . However, the coercive force when no current was applied was 1.8 kOe from the IH phase diagram. As expected from the damping constant, when the magnetic layer is changed from Co to Co ₈₀ Fe ₂₀ , the current density normalized by the coercive force is lowered, so it can be said that a reduction in current is realized.

  As described above, an artificial lattice is formed using Au as the nonmagnetic material and CoFe as the magnetic material, and this artificial lattice is used for the recording layer, thereby realizing a GMR element capable of low current density spin injection inversion.

Next, the inventors conducted intensive studies with an MTJ structure as shown in FIG. 6 in order to achieve a high magnetoresistance ratio. The stacked structure of FIG. 6 has a thermal oxide film-provided Si substrate 11 on which Ta layer having a film thickness of about 5 nm is formed as an adhesion layer 13 with the underlayer 14, Co ₄₀ Fe ₄₀ B _{20 having} a film thickness of about 3 nm as the underlayer 14 MgO having a thickness of about 0.5 nm, TiN having a thickness of about 20 nm, and Pd having a thickness of about 3 nm were sequentially formed. On the underlayer 14, FePtB having a thickness of about 10 nm and Co ₄₀ Fe ₄₀ B ₂₀ having a thickness of about 2 nm were sequentially formed as the fixed layer 15. FePtB was formed by heating at 400 ° C. On the fixed layer 15, MgO having a thickness of about 1 nm was sequentially formed as a tunnel barrier layer 16, a recording layer 17 made of an artificial lattice described later, and Ru having a thickness of about 5 nm were formed as a protective layer 18. Ta having a film thickness of about 100 nm was formed on the hard mask 19 necessary for element processing.

  The recording layer 17 is an artificial lattice [Pd 1 nm / Co 0.3 nm] in which CoFeB with a thickness of about 1 nm and Pd with a thickness of about 1 nm, and Co with a thickness of about 0.3 nm and Pd with a thickness of about 1 nm are stacked in two periods. 2 / Pd 1 nm / CoFeB 1 nm. Specifically, the recording layer 17 includes CoFeB having a thickness of about 1 nm as the first magnetic layer 17A-1, Pd having a thickness of about 1 nm as the first nonmagnetic layer 17B-1, and the second magnetic layer 17A-. 2 is about 0.3 nm thick Co, the second nonmagnetic layer 17B-2 is about 1 nm thick Pd, the third magnetic layer 17A-3 is about 0.3 nm thick Co, The magnetic layer 17B-3 is an artificial lattice in which Pd with a thickness of about 1 nm is sequentially stacked.

  As the tunnel barrier layer 16, an insulator having a NaCl structure and oriented in the (100) plane is used. In order to realize a high magnetoresistance ratio, it is important that MgO as the tunnel barrier layer 16 is oriented in the (100) plane. MgO has a NaCl structure. As a formation process of the recording layer 17, after forming the fixed layer 15 and the tunnel barrier layer 16, CoFeB 1 nm as the first magnetic layer 17A-1 of the recording layer 17 is formed, and annealed in vacuum at 300 ° C. for 2 hours, A high MR ratio is realized by forming a crystal orientation relationship of CoFeB (100) / MgO (100) / CoFeB (100). Then, after this annealing treatment, formation is performed again from the nonmagnetic material constituting the artificial lattice. With the MTJ structure configured as described above, an MR ratio of 100% could be realized. The crystal orientation of CoFeB (100) / MgO (100) / CoFeB (100) is preferably realized over the entire film. For example, there are sites with different orientations such as crystal grains with different orientation planes and stacking faults. The MR ratio may be included in a range that does not greatly deteriorate the MR ratio.

Similarly, the recording layer 17 is formed by laminating two periods of CoFeB having a thickness of about 1 nm, Pd having a thickness of about 1 nm, Co ₈₀ Fe ₂₀ having a thickness of about 0.3 nm, and a Pd—Au alloy having a thickness of about 1 nm. Artificial lattice [Pd—Au 1 nm / CoFe 0.3 nm] 2 / Pd 1 nm / CoFeB 1 nm. Specifically, the recording layer 17 includes CoFeB having a thickness of about 1 nm as the first magnetic layer 17A-1, Pd having a thickness of about 1 nm as the first nonmagnetic layer 17B-1, and the second magnetic layer 17A-. 2, Co ₈₀ Fe _{20 with} a film thickness of about 0.3 nm, Pd—Au alloy with a film thickness of about 1 nm as the second nonmagnetic layer 17B-2, and a film thickness of about 0.3 nm as the third magnetic layer 17A-3. Co ₈₀ Fe ₂₀ and the third nonmagnetic layer 17B-3 are made of an artificial lattice in which Pd—Au alloys having a thickness of about 1 nm are sequentially stacked. With the MTJ structure configured as described above, an MR ratio of 90% could be realized.

  Since the recording layer 17 is formed of CoFeB 1 nm as a magnetic layer in contact with the tunnel barrier layer 16 so as to realize a high MR ratio, perpendicular magnetic anisotropy can be realized when Au is used as the nonmagnetic layer. difficult. For this reason, Pd is used for the nonmagnetic layer on CoFeB. Further, the nonmagnetic layer thereon is made of an Au—Pd alloy to which Pd is added at 50 at% in order to further reduce the damping constant. That is, it is difficult to achieve a high MR ratio simply by using Co / Au, and it is necessary to appropriately set each magnetic material and film thickness and non-magnetic material and film thickness constituting the artificial lattice.

  The nonmagnetic layer in contact with the magnetic layer (CoFeB in the above example) in contact with the intermediate layer (tunnel barrier layer) is not limited to Pd, and a Pd—Au alloy may be used. In this case, the Pd composition of the Pd—Au alloy in the nonmagnetic layer in contact with the magnetic layer may be made larger than the Pd composition of the Pd—Au alloy in the nonmagnetic layer not in contact. For example, the Pd composition of the nonmagnetic layer in contact with the magnetic layer can be in the range of 20 at% to 90 at%, and the Pd composition of the nonmagnetic layer not in contact can be in the range of 10 at% to 55 at%. Even in such a range, it is possible to achieve a desired MR ratio while maintaining perpendicular magnetic anisotropy.

In order to realize a high magnetoresistance ratio, the first magnetic layer 17A-1 in contact with the tunnel barrier layer 16 should have a cubic structure or a tetragonal structure and be oriented in the (100) plane. desirable. For this reason, the first magnetic layer 17A-1 is configured by adding boron (B) to a CoFe alloy. If the concentration of boron (B) is too large, the perpendicular magnetic anisotropy deteriorates, and therefore it is preferably 30 at% or less. Specifically, in consideration of the above-described concentration of iron (Fe), the first magnetic layer 17A-1 includes an alloy (Co _100-x ) containing cobalt (Co), iron (Fe), and boron (B). -fe _x) consists _{100-y B y, x ≧} 20at%, is set to 0 <y ≦ 30at%.

  In order to achieve both a high perpendicular magnetic anisotropy and a high MR ratio, the first magnetic layer 17A-1 in contact with the tunnel barrier layer 16 is formed of a magnetic layer (17A-2, 17A-3) is set larger than the film thickness. Specifically, the film thickness of the first magnetic layer 17A-1 in contact with the tunnel barrier layer 16 while satisfying the above relationship is set to 0.5 to 1 from the viewpoint of perpendicular magnetic anisotropy and high MR ratio. It is preferably about 5 nm. The film thickness of the magnetic layers (17A-2, 17A-3) not in contact with the tunnel barrier layer 16 may be appropriately adjusted depending on the balance of perpendicular magnetic anisotropy and damping constant, but is in the range of 0.2 to 1 nm. Preferably there is. If the film thickness of the nonmagnetic layers (17B-1, 17B-2, and 17B-3) is too thick, it is not preferable because the exchange coupling between the magnetic materials becomes weak, and is about 0.5 to 1.5 nm. It is preferable that

[2] Magnetoresistive element (MTJ element)
An MTJ (Magnetic Tunnel Junction) element 10 used for a memory or the like can be configured using the recording layer 17 composed of the artificial lattice described above. Hereinafter, an embodiment in which the recording layer 17 composed of an artificial lattice is applied to an MTJ element will be described.

[2-1] Single Pin Structure FIG. 7 is a schematic diagram of the MTJ element 10 having a single pin structure according to the first embodiment. The arrows in FIG. 7 indicate the magnetization direction. The single pin structure is a structure in which a recording layer and a fixed layer are laminated via an intermediate layer.

  As shown in FIG. 7, the MTJ element 10 includes a fixed layer (also referred to as a pinned layer) 15 made of a magnetic material, a recording layer (also referred to as a free layer) 17 made of a magnetic material, a fixed layer 15 and a recording layer 17. It has a laminated structure having an intermediate layer (nonmagnetic layer) 16 sandwiched between them. In the so-called perpendicular magnetization type MTJ element 10, the fixed layer 15 and the recording layer 17 have perpendicular magnetic anisotropy, and the magnetization directions of the fixed layer 15 and the recording layer 17 are perpendicular to the film surface. . In addition, the direction of magnetization (or spin) of the fixed layer 15 is fixed. The recording layer 17 can change (reverse) the magnetization direction.

In the MTJ element 10, the nonmagnetic layer 16 is an insulator and has a TMR (Tunneling Magnetoresistive) effect. Here, when the nonmagnetic layer 16 is an insulator, magnesium oxide (MgO), aluminum oxide (AlO _x ), or the like is used. When the nonmagnetic layer 16 is a metal, it is a GMR element and has a GMR (Giant Magnetoresistive) effect. When the nonmagnetic layer 16 is a metal, gold (Au), silver (Ag), copper (Cu), or the like is used. In this embodiment, when the nonmagnetic layer 16 is a metal, Au is most preferable as described above. By using Au for the nonmagnetic layer 16, the damping constant can be reduced and the reversal current density can be reduced.

(Operation)
The MTJ element 10 is a spin injection type magnetoresistive element. Accordingly, when data is written to the MTJ element 10 or when data is read from the MTJ element 10, the MTJ element 10 is energized in both directions in a direction perpendicular to the film surface (or the laminated surface). In the MTJ element 10, the magnetization arrangement of the two magnetic layers (the recording layer 17 and the fixed layer 15) is a parallel arrangement or an anti-parallel arrangement. The MTJ element 10 can be used as a storage element by associating information of “0” and “1” with the resistance value of the MTJ element 10 that changes depending on the magnetization arrangement.

  Specifically, when electrons are supplied from the fixed layer 15 side (that is, electrons traveling from the fixed layer 15 to the recording layer 17), the electrons that are spin-polarized in the same direction as the magnetization direction of the fixed layer 15 are recorded. Injected into. In this case, the magnetization direction of the recording layer 17 is aligned with the same direction as the magnetization direction of the fixed layer 15. Thereby, the magnetization directions of the fixed layer 15 and the recording layer 17 are arranged in parallel. In this parallel arrangement, the resistance value of the MTJ element 10 is the smallest, and this case is defined as, for example, data “0”.

  On the other hand, when electrons are supplied from the recording layer 17 side (that is, electrons traveling from the recording layer 17 to the fixed layer 15), the electrons are reflected by the fixed layer 15 to be spin-polarized in the direction opposite to the magnetization direction of the fixed layer 15. Electrons are injected into the recording layer 17. In this case, the magnetization direction of the recording layer 17 is aligned with the direction opposite to the magnetization direction of the fixed layer 15. Thereby, the magnetization directions of the fixed layer 15 and the recording layer 17 are antiparallel. In this antiparallel arrangement, the MTJ element 10 has the largest resistance value, and this case is defined as, for example, data “1”.

(Magnetic material)
In the MTJ element 10, a high-performance MTJ element 10 is realized by using a magnetic layer having a large magnetization reversal current as the fixed layer 15 and using a magnetic layer having a smaller magnetization reversal current than the fixed layer 15 as the recording layer 17. Can do. When the magnetization reversal is caused by the spin-polarized current, the reversal current is proportional to the saturation magnetization, the anisotropic magnetic field, and the volume. Therefore, the reversal current between the recording layer 17 and the fixed layer 15 is adjusted appropriately. You can make a difference.

In the present embodiment, the recording layer 17 is composed of an artificial lattice, but the fixed layer 15 can be appropriately selected from the materials shown below. As a magnetic material constituting the fixed layer 15 that realizes perpendicular magnetization, for example, a material having a magnetocrystalline anisotropy energy density of 5 × 10 ⁵ erg / cc or more is desirable, and specific examples are given below.

(1) Irregular alloy Irregular alloy is mainly composed of cobalt (Co), chromium (Cr), tantalum (Ta), niobium (Nb), vanadium (V), tungsten (W), hafnium (Hf), It is composed of an alloy containing one or more elements of titanium (Ti), zirconium (Zr), platinum (Pt), palladium (Pd), iron (Fe), and nickel (Ni). Examples thereof include CoCr, CoPt, CoCrTa, CoCrPt, CoCrPtTa, and CoCrNb. These alloys can adjust the magnetic anisotropy energy density and saturation magnetization by increasing the proportion of nonmagnetic elements.

(2) Ordered Alloy The ordered alloy is composed of one or more elements of iron (Fe), cobalt (Co), and nickel (Ni), and one or more elements of palladium (Pd) and platinum (Pt). it is composed of a, and a ferromagnetic alloy crystal structure L1 ₀ structure (ordered alloy). Examples thereof include Fe ₅₀ Pt ₅₀ , Fe ₅₀ Pd ₅₀ , Co ₅₀ Pt ₅₀ , Fe ₃₀ Ni ₂₀ Pt ₅₀ , Co ₃₀ Fe ₂₀ Pt ₅₀ , and Co ₃₀ Ni ₂₀ Pt ₅₀ . These ordered alloys are not limited to the above composition ratio. By adding an impurity element such as Cu (copper), chromium (Cr), silver (Ag), or an alloy thereof, or an insulator to these ordered alloys, the magnetic anisotropy energy density and the saturation magnetization can be adjusted to be low.

(3) Artificial lattice The artificial lattice can be used as a fixed layer by appropriately adjusting the magnetic anisotropy energy density and saturation magnetization. One or more elements of iron (Fe), cobalt (Co), and nickel (Ni), or an alloy containing one element, chromium (Cr), platinum (Pt), palladium (Pd), iridium (Ir) , Rhodium (Rh), ruthenium (Ru), osmium (Os), rhenium (Re), gold (Au), and copper (Cu) are laminated alternately with one element or an alloy containing one element. A structure can be used. Examples thereof include artificial lattices such as Co / Pt, Co / Pd, CoCr / Pt, Co / Ru, Co / Os, Co / Au, and Ni / Cu. These artificial lattices can adjust the magnetic anisotropy energy density and the saturation magnetization by adding an element to the magnetic layer or adjusting the film thickness ratio of the magnetic layer to the nonmagnetic layer.

(4) Ferrimagnetic material As the ferrimagnetic material, an alloy of a rare earth metal and a transition metal is used. Specifically, an amorphous alloy composed of terbium (Tb), dysprosium (Dy), or gadolinium (Gd) and one or more elements of transition metals is used. Examples of such ferrimagnetic materials include TbFe, TbCo, TbFeCo, DyTbFeCo, GdTbCo, and the like. These alloys can adjust magnetic anisotropy energy density and saturation magnetization by adjusting the composition.

The magnetic layer may have a structure in which the magnetic part and the non-magnetic part are separated by segregation of the non-magnetic part. For example, oxides, nitrides, and carbides such as silicon oxide (SiO ₂ ), magnesium oxide (MgO), silicon nitride (SiN), and silicon carbide (SiC) may be used as the non-magnetic part. An alloy such as a nonmagnetic CoCr alloy that is as large as% or more may be used.

  Further, at the interface of the magnetic layers (recording layer 17 and fixed layer 15) in contact with the nonmagnetic layer 16 of the MTJ element 10, iron (Fe), cobalt (Co), and nickel (Ni) are used as high polarizability materials. A magnetic metal layer made of one or more elements or an alloy containing one element may be arranged to increase the magnetoresistance ratio. However, since this magnetic metal layer usually has in-plane magnetization in a single layer, the magnetic film thickness ratio with the perpendicular magnetic anisotropic material laminated on the magnetic metal layer is not impaired so as not to impair the stability of perpendicular magnetization. Need to be adjusted.

  In addition, each of the recording layer 17 and the fixed layer 15 may have a structure in which magnetic layers are stacked, and one of the magnetic layers may have a so-called granular structure in which a magnetic material is dispersed.

  A specific example of the MTJ element 10 having a single pin structure will be described below.

(A) Specific example 1-1
In the MTJ element 10 of Specific Example 1-1, the fixed layer 15 and the recording layer 17 are each composed of an artificial lattice. FIG. 8 is a cross-sectional view showing a configuration of the MTJ element 10 according to Example 1-1.

As shown in FIG. 8, the MTJ element 10 has a thermal oxide film-attached Si substrate 11, Ta having a thickness of about 5 nm as an adhesion layer 13 with the base layer 14, Ru having a thickness of about 10 nm as the base layer 14, An artificial lattice CoFeB1 in which Pt having a thickness of about 1 nm and Co having a thickness of about 0.3 nm are stacked as the fixed layer 15 on the ground layer 14 for eight periods, and the magnetic layer in the ninth period is CoFeB having a thickness of about 1.5 nm. .5nm / Pt1nm / [Co0.3nm / Pt1nm ] 8, the film thickness 1nm about MgO as a tunnel barrier layer 16, _Co 50 having a thickness of about 0.5nm as the recording layer 17 _{Fe 50} and the thickness 1nm about Pd, further An artificial lattice [Pd1 nm / CoFe0.3 nm] 2 / Pd1 nm / CoFe0.5 nm, in which Co ₈₀ Fe ₂₀ with a thickness of about 0.3 nm and Pd with a thickness of about 1 nm are stacked in two cycles. Ru having a thickness of about 5 nm was sequentially formed as the protective layer 18. Ta having a film thickness of about 100 nm was formed on the hard mask 19 necessary for element processing. The adhesion layer 13 also functions as a lower electrode, and the hard mask 19 also functions as an upper electrode.

  As the formation process of the recording layer 17, after forming the fixed layer 15 and the tunnel barrier layer 16, the first magnetic layer CoFe 0.5 nm of the recording layer 17 is formed and annealed in vacuum at 300 ° C. for 2 hours to obtain CoFe (100 ) / MgO (100) / CoFeB (100) relationship is formed to achieve a high MR ratio. Then, after this annealing treatment, formation is started again from the nonmagnetic material constituting the artificial lattice. In the MTJ element 10 of the specific example 1-1 configured as described above, an MR ratio of 50% was realized.

  The configuration of Specific Example 1-1 described above has a so-called bottom pin structure in which the fixed layer 15 is disposed on the lower side (substrate side) and the recording layer 17 is disposed on the upper side with respect to the tunnel barrier layer 16. A configuration similar to that of Example 1-1 may be a so-called top pin structure in which the fixed layer 15 is disposed on the upper side and the recording layer 17 is disposed on the lower side (substrate side) with respect to the tunnel barrier layer 16. .

  In both the bottom pin structure and the top pin structure, an antiferromagnetic layer may be provided adjacent to fix the fixed layer 15 in one direction. The antiferromagnetic layer includes manganese (Mn), iron (Fe), nickel (Ni), platinum (Pt), palladium (Pd), ruthenium (Ru), osmium (Os), or iridium (Ir). FeMn, NiMn, PtMn, PtPdMn, RuMn, OsMn, IrMn, and the like that are alloys of the above can be used.

(B) Specific example 1-2
MTJ element 10 of the embodiment 1-2, except the fixed layer 15 of the embodiment 1-1 is a FePt ordered alloy L1 ₀ structure has almost the same structure as in example 1-1.

MTJ element 10 has a magnetoresistance ratio on Si substrate 11 with a thermal oxide film, FePtB having a thickness of about 10 nm as adhesion layer 13 with base layer 14 and about 10 nm as a fixed layer 15 on base layer 14. In order to increase the thickness, Co ₄₀ Fe ₄₀ B ₂₀ having a thickness of about 2 nm is laminated. The FePtB of the fixed layer 15 is formed while heating the substrate at 400 ° C. On the fixed layer 15, MgO having a thickness of about 1 nm as the tunnel barrier layer 16, Co ₄₀ Fe ₄₀ B ₂₀ having a thickness of about 1 nm and Pd having a thickness of about 1 nm as the recording layer 17, and further having a thickness of about 0.3 nm. An artificial lattice [Pd 1 nm / CoFe 0.3 nm] 2 / Pd 1 nm / CoFeB 1 nm, in which Co ₈₀ Fe ₂₀ and Pd having a thickness of about 1 nm are laminated, and Ru having a thickness of about 5 nm were sequentially formed as the protective layer 18. A 100 nm thick Ta film was formed on the hard mask 19 required for device processing.

  As the formation process of the recording layer 17, after forming the fixed layer 15 and the tunnel barrier layer 16, the first magnetic layer CoFeB 1 nm of the recording layer 17 is formed and annealed in vacuum at 300 ° C. for 2 hours to obtain CoFeB (100) / A high MR ratio is realized by forming a crystal orientation relationship of MgO (100) / CoFeB (100). Then, after this annealing treatment, formation is started again from the nonmagnetic material constituting the artificial lattice.

In the MTJ element 10 of the specific example 1-2 configured as described above, an MR ratio of 90% was realized. Further, by using the ordered alloy in the fixed layer 15 having an L1 ₀ structure, it is possible to configure the fixed layer 15 having a good vertical magnetic anisotropy.

[2-2] Dual Pin Structure FIG. 9 is a schematic diagram of the MTJ element 10 having a dual pin structure according to the first embodiment. The dual pin structure is a structure in which two fixed layers are disposed on both sides of the recording layer via intermediate layers.

  As shown in FIG. 9, the MTJ element 10 includes a recording layer 17 made of a magnetic material, first and second fixed layers 15 and 22 made of a magnetic material, and a recording layer 17 and a first fixed layer 15. The laminated structure includes an intermediate layer (nonmagnetic layer) 16 sandwiched and an intermediate layer (nonmagnetic layer) 21 sandwiched between the recording layer 17 and the second pinned layer 22. In the so-called perpendicular magnetization type MTJ element 10, the magnetization directions of the fixed layers 15 and 22 and the recording layer 17 are perpendicular to the film surface. Here, the first and second fixed layers 15 and 22 have an antiparallel arrangement in which the magnetizations are directed in opposite directions.

As the nonmagnetic layers 16 and 21, an insulator such as magnesium oxide (MgO) and aluminum oxide (AlO _x ), a metal such as gold (Au), silver (Ag), and copper (Cu), or an alloy thereof is used. It is done. In the present embodiment, Au is most preferable when the nonmagnetic layer is a metal. By using Au for the nonmagnetic layer, the reversal current density can be reduced.

  Here, in the MTJ element 10 having the dual pin structure, two magnetic layers (the recording layer 17 and the fixed layer 15) sandwiching the nonmagnetic layer 16 and two magnetic layers (the recording layer 17 and the fixed layer) sandwiching the nonmagnetic layer 21 are interposed. 22) takes a parallel or anti-parallel arrangement. However, since the parallel arrangement and the antiparallel arrangement exist at the same time when viewed as the entire MTJ element 10, it is necessary to provide a difference in the MR ratio via the nonmagnetic layers 16 and 21.

  Therefore, when the nonmagnetic layer 16 is a tunnel barrier layer and the nonmagnetic layer 21 is a metal (spacer layer), the MR ratio generated in the tunnel barrier layer 16 is larger than the MR ratio generated in the nonmagnetic layer 21. . Therefore, the magnetization arrangement of the two magnetic layers (the recording layer 17 and the fixed layer 15) sandwiching the tunnel barrier layer 16 is made to correspond to information of “0” and “1”.

  As the material for the recording layer 17 and the fixed layers 15 and 22, the same material as the single pin structure can be used.

(Operation)
The operation of the dual pin structure MTJ element 10 will be described. When writing data to the MTJ element 10 or reading data from the MTJ element 10, the MTJ element 10 is energized in both directions in a direction perpendicular to the film surface (or laminated surface).

  When electrons are supplied from the fixed layer 15 side (that is, electrons traveling from the fixed layer 15 to the recording layer 17), the electrons that are spin-polarized in the same direction as the magnetization direction of the fixed layer 15 are reflected by the fixed layer 22. As a result, electrons that are spin-polarized in the direction opposite to the magnetization direction of the fixed layer 22 are injected into the recording layer 17. In this case, the magnetization direction of the recording layer 17 is aligned with the same direction as the magnetization direction of the fixed layer 15. Thereby, the magnetization directions of the fixed layer 15 and the recording layer 17 are arranged in parallel. Thereby, the magnetization directions of the fixed layer 15 and the recording layer 17 are arranged in parallel. In this parallel arrangement, the resistance value of the MTJ element 10 is the smallest, and this case is defined as, for example, data “0”.

  On the other hand, when electrons are supplied from the fixed layer 22 side (that is, electrons traveling from the fixed layer 22 to the recording layer 17), electrons that are spin-polarized in the same direction as the magnetization direction of the fixed layer 22 are reflected by the fixed layer 15. As a result, electrons spin-polarized in the direction opposite to the magnetization direction of the fixed layer 15 are injected into the recording layer 17. In this case, the magnetization direction of the recording layer 17 is aligned with the direction opposite to the magnetization direction of the fixed layer 15. In this antiparallel arrangement, the MTJ element 10 has the largest resistance value, and this case is defined as, for example, data “1”.

  As described above, since the MTJ element 10 has a dual pin structure in which the fixed layers 15 and 22 are arranged on both sides of the recording layer 17, the effect of reflection of spin-polarized electrons can be used more. Furthermore, the magnetization reversal current can be reduced.

  A specific example of the MTJ element 10 having a dual pin structure will be described below.

(A) Specific example 2-1
In the MTJ element 10 of Specific Example 2-1, the fixed layers 15 and 22 and the recording layer 17 are each composed of an artificial lattice. FIG. 10 is a cross-sectional view illustrating a configuration of the MTJ element 10 according to Specific Example 2-1.

The MTJ element 10 is formed on a Si substrate 11 with a thermal oxide film, Ta having a thickness of about 5 nm as an adhesion layer 13 with the base layer 14, Ru having a thickness of about 10 nm as the base layer 14, and a fixed layer 15 on the base layer 14. As an artificial lattice CoFeB1.5 nm / Pd1 nm / [Co0, in which Pd having a thickness of about 1 nm and Co having a thickness of about 0.3 nm are stacked for eight periods, and the magnetic layer in the ninth period is CoFeB having a thickness of about 1.5 nm. .3 nm / Pd1 nm] 8, MgO with a thickness of about 1 nm as the tunnel barrier layer 16, Co ₄₀ Fe ₄₀ B ₂₀ with a thickness of about 1 nm and Pd with a thickness of about 1 nm as the recording layer 17, and a thickness of about 0.3 nm An artificial lattice [Pd1 nm / CoFe0.3 nm] 2 / Pd1 nm / CoFeB1 nm in which Co ₈₀ Fe ₂₀ and Pd having a thickness of about 1 nm were stacked in two cycles was sequentially formed.

  As the formation process of the recording layer 17, after forming the fixed layer 15 and the tunnel barrier layer 16, the first magnetic layer CoFeB 1 nm of the recording layer 17 is formed and annealed in vacuum at 300 ° C. for 2 hours to obtain CoFeB (100) / A high MR ratio is realized by forming a crystal orientation relationship of MgO (100) / CoFeB (100). After this annealing, Pd and [Pd 1 nm / CoFe 0.3 nm] 2 having a thickness of about 1 nm constituting the artificial lattice are sequentially formed.

  On the recording layer 17, an artificial lattice [CoFe 0.5 nm / min, in which Au of about 4 nm thickness as the spacer layer 21 and CoFe of about 0.5 nm thickness and Pt of about 1 nm thickness are laminated as the fixed layer 22. Pt 1 nm] and a protective layer 18 were formed of Ru having a thickness of about 5 nm. Ta having a film thickness of about 100 nm was formed on the hard mask 19 necessary for element processing.

  The coercive force of the fixed layer 22 is larger than the coercive force of the fixed layer 15, and the magnetization arrangement of the fixed layer 15 and the fixed layer 22 can be set antiparallel using the difference in coercive force. That is, it is sufficient to perform magnetization twice. First, by the first magnetic field application, the magnetization of the fixed layer 15 and the magnetization of the recording layer 17 and the fixed layer 22 are arranged in the same direction. Thereafter, the second magnetic field application is performed in the opposite direction to the first. The second applied magnetic field is set larger than the coercive force of the fixed layer 15 and smaller than the coercive force of the fixed layer 22. Thereby, the magnetization directions of the recording layer 17 and the fixed layer 15 are opposite to the magnetization direction of the fixed layer 22. In this way, a magnetization arrangement as shown in FIG. 10 can be realized.

In the configuration of the specific example 2-1, the change in magnetoresistance through the MgO of the tunnel barrier layer 16 is larger than the change in magnetoresistance through the Au of the spacer layer 21. Information is stored by the magnetization arrangement of the fixed layer 15 and the magnetization arrangement of the recording layer 17 and the fixed layer 22. Note that a magnetic material having a high polarizability may be provided as an interface layer at the interface between the recording layer 17 and the tunnel barrier layer 16 and at the interface between the recording layer 17 and the spacer layer 21. The spacer layer 21 may be made of an insulator such as magnesium oxide (MgO) or aluminum oxide (AlO _x ). In this case, if the resistance and MR ratio of the spacer layer 21 are made smaller than that of the tunnel barrier layer 16, there is no problem in operation.

Similarly, in the MTJ element 10 described above, the fixed layer 22 may be composed of two layers of Tb ₃₀ (Co ₈₀ Fe ₂₀ ) ₇₀ having a thickness of about ₃₀ nm and Fe having a thickness of about 2 nm. Here, Tb ₂₄ (Co ₈₀ Fe ₂₀ ) ₇₆ is the compensation composition. In this case, the fixed layer 22 has a large magnetic moment of the rare earth metal (RE), and even when combined with the laminated Fe, the magnetic moment of the RE is large as a whole. In this case, a magnetic field arrangement equivalent to the magnetization arrangement of the fixed layers 15 and 22 in FIG. 10 can be realized by magnetizing only once in one direction. That is, the magnetic moment of the transition metal (TM) in the fixed layer 22 is smaller than the magnetic moment of the RE, and the magnetic moment of the transition metal (TM) is opposite to the magnetic moment of the RE. Face the opposite direction.

  In addition, as described in the specific examples 1-1 and 1-2, the fixed layers 15 and 22 can be appropriately selected from ordered alloys, irregular alloys, artificial lattices, ferrimagnetic materials, and the like.

  In order to fix the magnetizations of the fixed layers 15 and 22 in one direction, an antiferromagnetic layer may be provided adjacently. The antiferromagnetic layer includes manganese (Mn), iron (Fe), nickel (Ni), platinum (Pt), palladium (Pd), ruthenium (Ru), osmium (Os), or iridium (Ir). FeMn, NiMn, PtMn, PtPdMn, RuMn, OsMn, IrMn, and the like that are alloys of the above can be used.

(A) Specific example 2-2
MTJ element 10 of the embodiment 2-2 has been fixed layer 15 is composed of FePt ordered alloy having the L1 ₀ structure, also has TMR structure on the lower side (substrate side), a GMR structure on the upper side . FIG. 11 is a cross-sectional view illustrating a configuration of the MTJ element 10 according to Specific Example 2-2.

The MTJ element 10 is formed on a Si substrate 11 with a thermal oxide film, Ta having a thickness of about 10 nm as an adhesion layer 13 with the base layer 14, Ru having a thickness of about 10 nm as the base layer 14, and a fixed layer 15 on the base layer 14. FePtB having a thickness of about 10 nm, Co ₄₀ Fe ₄₀ B _{20 having} a thickness of about 2 nm as the interface layer 15A for increasing the magnetoresistance ratio, MgO having a thickness of about 2 nm as the tunnel barrier layer 16, and a thickness of about 1 nm as the recording layer 17. An artificial lattice [Pd1 nm / CoFe0.3 nm] 2 / Pd1 nm / CoFeB1 nm in which two periods of CoFeB, Pd having a thickness of about 1 nm, Co ₈₀ Fe ₂₀ having a thickness of about 0.3 nm, and Pd having a thickness of about 1 nm are stacked. Sequentially formed.

Since the fixed layer 15 and the interface layer 15A are exchange-coupled, they behave as one magnetic layer (fixed layer). In order to realize a high magnetoresistance ratio, it is desirable that the interface layer 15A in contact with the tunnel barrier layer 16 has a cubic or tetragonal structure and is oriented in the (100) plane. Therefore, the interface layer 15A is configured by adding boron (B) to a CoFe alloy. If the concentration of boron (B) is too large, the perpendicular magnetic anisotropy deteriorates, and therefore it is preferably 30 at% or less. Specifically, the interface layer 15A is comprised of cobalt (Co), iron (Fe), and an alloy _{(Co 100-x -Fe x)} 100-y B y containing boron (B), x ≧ 20at% , 0 <y ≦ 30 at% is set.

  As the formation process of the recording layer 17, after forming the fixed layer 15, the interface layer 15A, and the tunnel barrier layer 16, the first magnetic layer CoFeB 1 nm of the recording layer 17 is formed, and annealed in vacuum at 300 ° C. for 2 hours to obtain CoFeB. A high MR ratio is realized by forming a crystal orientation relationship of (100) / MgO (100) / CoFeB (100). After this annealing, Pd and [Pd 1 nm / CoFe 0.3 nm] 2 having a thickness of about 1 nm are sequentially formed.

  On the recording layer 17, an artificial lattice [Co 0.3 nm / Co, in which Au having a thickness of about 4 nm as the spacer layer 21 and Pt having a thickness of about 1 nm and Co having a thickness of about 0.3 nm are stacked as the fixed layer 22. Pt 1 nm] and a protective layer 18 were formed of Ru having a thickness of about 5 nm. On the hard mask 19 necessary for element processing, Ru having a film thickness of about 35 nm and Ta having a film thickness of about 60 nm were sequentially formed.

In this manner, by using the ferromagnetic alloy having an L1 ₀ structure as a fixed layer 15 (ordered alloy), it is possible to configure the fixed layer 15 having a good vertical magnetic anisotropy. Further, the fixed layer 22 may be constituted by ordered alloy having the L1 ₀ structure. Furthermore, in order to fix the magnetization of the fixed layers 15 and 22 in one direction, an antiferromagnetic layer may be provided adjacently.

(C) Specific example 2-3
The MTJ element 10 of Example 2-3 has a configuration in which a TMR structure having a tunnel barrier layer is disposed on the upper side and a GMR structure having a spacer layer is disposed on the lower side (substrate side). FIG. 12 is a cross-sectional view illustrating a configuration of the MTJ element 10 according to Specific Example 2-3.

After the formation up to the fixed layer 15 as in Example 2-1, the spacer layer 16 is about 4 nm thick Au, the recording layer 17 is about 0.5 nm thick CoFe, the thickness is about 1 nm Au—Pd, and the film thickness. Co ₄₀ Fe ₄₀ B ₂₀ having a thickness of about 1 nm was sequentially formed. On the recording layer 17, MgO having a film thickness of about 1 nm was formed as the tunnel barrier layer 21, and the configuration subsequent to the tunnel barrier layer 21 was sequentially formed in the same configuration as in Example 2-1.

  As described in the specific examples 1-1 and 1-2, the fixed layers 15 and 22 can be appropriately selected from ordered alloys, irregular alloys, artificial lattices, ferrimagnetic materials, and the like. In order to fix the magnetization of the fixed layers 15 and 22 in one direction, an antiferromagnetic layer may be provided adjacent to them.

(D) Specific Example 2-4
In the MTJ element 10 of Specific Example 2-4, the intermediate layers (nonmagnetic layers) 16 and 21 are made of an insulator, and both the lower side (substrate side) and the upper side have a TMR structure. FIG. 13 is a cross-sectional view illustrating a configuration of the MTJ element 10 of Specific Example 2-4. The MTJ element 10 of the specific example 2-4 is the same as the specific example 2-2 except that the nonmagnetic layer 21 is an insulator and the fixed layer 22 has a stacked structure of CoFeB and TbCoFe.

After the formation up to the recording layer 17 in the same manner as in Example 2-2, on the recording layer 17, MgO having a thickness of about 1 nm as the tunnel barrier layer 21 and Co ₄₀ Fe ₄₀ B ₂₀ having a thickness of about 2 nm as the fixed layer 22 are formed. A laminated structure with Tb ₃₀ (Co ₈₀ Fe ₂₀ ) ₇₀ having a thickness of about 30 nm was sequentially formed. Here, Tb ₂₄ (Co ₈₀ Fe ₂₀ ) ₇₆ is the compensation composition.

  On the fixed layer 22, Ru having a film thickness of about 5 nm was formed as the protective layer 18, and Ru having a film thickness of about 35 nm and Ta having a film thickness of about 60 nm were sequentially formed as the hard mask 19 required for device processing. In order to fix the magnetizations of the fixed layers 15 and 22 in one direction, an antiferromagnetic layer may be provided adjacent to them.

  In the MTJ element 10 of Example 2-4, the tunnel barrier layer 16 is MgO having a thickness of about 2 nm, while the MgO of the tunnel barrier layer 21 is 1 nm in thickness, the resistance difference is large, and the magnetoresistance ratio is The tunnel barrier layer 16 becomes dominant.

(E) Specific Example 2-5
FIG. 14 is a cross-sectional view showing the configuration of the MTJ element 10 of Specific Example 2-5. The MTJ element 10 of Example 2-5 has the same configuration as that of Example 2-1 except that the fixed layer 22 has a SAF (Synthetic Anti-Ferromagnet) structure, and the TMR structure is on the lower side (substrate side). ), The GMR structure is arranged on the upper side. The SAF structure is a structure in which two magnetic layers are exchange-coupled antiferromagnetically. The pinned layer 22 includes a first magnetic layer 22-1, a second magnetic layer 22-3, and a nonmagnetic layer 22-sandwiched between the first and second magnetic layers 22-1 and 22-3. 2 and has a SAF structure in which the first and second magnetic layers 22-1 and 22-3 are exchange-coupled antiferromagnetically.

  In this case, since the magnetization arrangements of the first and second magnetic layers 22-1 and 22-3 are antiparallel, the leakage magnetic fields from the first and second magnetic layers 22-1 and 22-3 are canceled out. As a result, there is an effect of reducing the leakage magnetic field of the fixed layer 22. Further, the exchange-coupled magnetic layer improves thermal disturbance resistance as an effect of increasing the volume. Examples of the material of the nonmagnetic layer 22-2 include one element or an alloy containing one or more elements of ruthenium (Ru), osmium (Os), rhenium (Re), and rhodium (Rh).

  The layer configuration of the MTJ element 10 of Specific Example 2-5 will be described below. The configuration from the substrate 11 to the recording layer 17 is the same as that of Example 1-1.

  After Au having a thickness of about 4 nm is formed on the recording layer 17 as the spacer layer 21, the fixed layer 22 is formed with Pt having a thickness of about 1 nm and Co having a thickness of about 0.3 nm as the first magnetic layer 22-1. After forming the artificial lattice [Pt / Co] 4 laminated in four periods, Ru having a film thickness of about 0.9 nm is formed as the nonmagnetic layer 22-2 in order to realize antiferromagnetic exchange coupling. As the magnetic layer 22-3, an artificial lattice [Co / Pt] 5 in which Co having a thickness of about 0.3 nm and Pt having a thickness of about 1 nm were stacked for five periods was formed.

  Note that antiferromagnetic coupling can also be realized when the first and second magnetic layers 22-1 and 22-3 are made of a RE-TM alloy ferrimagnetic material. In this case, the nonmagnetic layer 22-2 is not necessarily used. An example thereof will be described with reference to FIGS. 15 and 16.

  The RE-TM alloy is in a state where the magnetic moment of the rare earth metal (RE) and the magnetic moment of the transition metal (TM) are antiferromagnetically coupled. It is known that when RE-TM alloys are laminated, REs and TMs are ferromagnetically coupled. In this case, since the magnetic moments of RE and TM cancel each other, the magnetic moment of the RE-TM alloy can be adjusted by the composition.

  For example, as shown in FIG. 15, in the case of the RE-TM alloy layer 22-1 in which the RE magnetic moment 41 is larger than the TM magnetic moment 42, the remaining magnetic moment 43 is in the same direction as the RE magnetic moment 41. When the RE-TM alloy layer 22-3 having a RE magnetic moment 44 larger than the TM magnetic moment 45 is laminated on the RE-TM alloy layer 22-1, the RE magnetic moments 41 and 44 and the TM magnetic moment are combined. 42 and 45 are in the same direction, and the magnetic moments 43 and 46 of the two RE-TM alloy layers 22-1 and 22-3 are in the same direction and are in a parallel state.

  On the other hand, when the RE-TM alloy layer 22-3 having a RE magnetic moment 44 smaller than the TM magnetic moment 45 is laminated on the RE-TM alloy layer 22-1, as shown in FIG. The magnetic moments 43 and 46 of the TM alloy layers 22-1 and 22-3 are in an antiparallel state.

For example, a Tb—Co alloy has a so-called compensation composition in which Tb is 22 at%, the magnetic moment of Tb is the same as the magnetic moment of Co, and the magnetic moment is almost zero. When Tb ₂₅ Co ₇₅ with a thickness of about 10 nm and Tb ₂₀ Co ₈₀ with a thickness of about 10 nm are stacked, their magnetic moments are antiparallel.

By using such a form, the fixed layer 22 in which the two magnetic layers 22-1 and 22-3 are coupled in antiparallel can be produced. For example, the first magnetic layer 22-1 constituting the fixed layer 22 is made of Tb ₂₆ (Fe ₇₁ Co ₂₉ ) ₇₄ having a thickness of about 15 nm, and the second magnetic layer 22-3 is Tb _{22 having a} thickness of about 20 nm. (Fe ₇₁ Co ₂₉ ) ₇₈ . Here, Tb ₂₄ (Fe ₇₁ Co ₂₉ ) ₇₆ is the compensation composition.

  In the MTJ element 10 having such a configuration, the same magnetization arrangement as that of the fixed layers 15 and 22 shown in FIG. 9 can be realized by magnetization only once in one direction. That is, the TM magnetic moment of the fixed layer 22 is smaller than the RE magnetic moment, and the TM magnetic moment is opposite to the RE magnetic moment, so the magnetization of the fixed layer 22 is opposite to the magnetized direction.

  Further, when the first and second magnetic layers 22-1 and 22-3 are made of RE-TM alloy, the nonmagnetic layer 22-2 is interposed between the first and second magnetic layers 22-1 and 22-3. It is also possible to realize antiferromagnetic coupling by providing. An example thereof will be described with reference to FIGS.

  The TM magnetic moments 42 and 45 of the first and second magnetic layers 22-1 and 22-3 shown in FIG. 17 are considered to be exchange-coupled through the nonmagnetic layer 22-2. Similarly, the TM magnetic moments 42 and 45 of the first and second magnetic layers 22-1 and 22-3 shown in FIG. 18 are considered to be exchange-coupled via the nonmagnetic layer 22-2.

  For example, as shown in FIG. 17, when a metal that anti-ferromagnetically couples Co is used as the nonmagnetic layer 22-2, the RE magnetic moment 41 of the RE-TM alloy layer 22-1 is changed to TM magnetic. On the other hand, the RE magnetic moment 44 of the RE-TM alloy layer 22-3 is set larger than the TM magnetic moment 45. That is, when the nonmagnetic layer 22-2 contributes to the antiferromagnetic coupling, the magnitude relationship between the TM magnetic moment 42 and the RE magnetic moment 41 and the magnitude relationship between the TM magnetic moment 45 and the RE magnetic moment 44 are as follows. If they are set to the same value, the magnetic moments of TM and RE cancel each other, and the magnetic moments 43 and 46 become antiparallel. The material of the nonmagnetic layer 22-2 for antiferromagnetically coupling Co is one element or one of ruthenium (Ru), osmium (Os), rhenium (Re), and rhodium (Rh). Examples include alloys containing the above elements.

  In addition, as shown in FIG. 18, when the metal that ferromagnetically couples Co is used as the nonmagnetic layer 22-2, the RE magnetic moment 41 of the RE-TM alloy layer 22-1 is changed to the TM magnetic moment. The RE magnetic moment 44 of the RE-TM alloy layer 22-3 is made smaller than the TM magnetic moment 45. That is, when the nonmagnetic layer 22-2 contributes to the ferromagnetic coupling, the magnitude relationship between the TM magnetic moment 42 and the RE magnetic moment 41 is reversed from the magnitude relationship between the TM magnetic moment 45 and the RE magnetic moment 44. Is set, the magnetic moments of TM and RE cancel each other, and the magnetic moments 43 and 46 become antiparallel. Note that examples of the material of the nonmagnetic layer 22-2 that ferromagnetically couples Co include platinum (Pt) and palladium (Pd). One or more elements or an alloy containing one or more elements can be used. .

  In addition, the fixed layer 22 may be configured by stacking a RE-TM alloy in which the RE magnetic moment is larger than the TM magnetic moment and a metal or alloy mainly composed of a transition metal.

  As described above in detail, in the first embodiment, the recording layer 17 is formed of an artificial lattice in which magnetic layers and nonmagnetic layers are alternately stacked. Then, the magnetic layer constituting the recording layer 17 is formed of an alloy containing cobalt (Co) and iron (Fe), and at least one of the nonmagnetic layers constituting the recording layer 17 is palladium (Pd) and gold (Au). It is comprised with the alloy containing. The magnetic layer 17A-1 in contact with the tunnel barrier layer 16 among the magnetic layers constituting the recording layer 17 is made of an alloy containing cobalt (Co), iron (Fe), and boron (B). The film thickness of the magnetic layer in contact is set larger than the film thickness of the magnetic layer not in contact with the tunnel barrier layer 16. As a result, it is possible to configure the recording layer 17 that can ensure the perpendicular magnetic anisotropy, reduce the damping constant (that is, reduce the write current), and achieve a high magnetoresistance ratio.

  Further, an insulator having a NaCl structure typified by MgO is used as the tunnel barrier layer 16, and includes cobalt (Co), iron (Fe), and boron (B) between the tunnel barrier layer 16 and the fixed layer 15. An interface layer 15A made of an alloy is disposed. Thereby, since the relationship of crystal orientation of CoFeB (100) / MgO (100) / CoFeB (100) can be formed, it becomes possible to realize a high magnetoresistance ratio.

  Further, as the magnetic layer constituting the recording layer 17, a Co—Fe alloy containing an iron (Fe) concentration of 20 at% or more is used. Thereby, the damping constant can be reduced while maintaining the perpendicular magnetic anisotropy of the recording layer 17.

Further, by using the ordered alloy in the fixed layer 15 having an L1 ₀ structure, it is possible to configure the fixed layer 15 having a good vertical magnetic anisotropy.

  When the artificial lattice is used as the recording layer, gold (Au) is used for the spacer layer provided between the recording layer and the fixed layer. As a result, a GMR structure capable of low current density spin injection inversion can be realized.

[Second Embodiment]
The second embodiment shows an example in which an MRAM is configured using the MTJ element 10 shown in the first embodiment.

  FIG. 19 is a circuit diagram showing a configuration of an MRAM according to the second embodiment of the present invention. The MRAM includes a memory cell array 50 having a plurality of memory cells MC arranged in a matrix. In the memory cell array 50, a plurality of bit line pairs BL, / BL are arranged so as to extend in the column direction. In the memory cell array 50, a plurality of word lines WL are arranged so as to extend in the row direction.

  Memory cells MC are arranged at the intersections between the bit lines BL and the word lines WL. Each memory cell MC includes an MTJ element 10 and a selection transistor 51 including an N-channel MOS transistor. One end of the MTJ element 10 is connected to the bit line BL. The other end of the MTJ element 10 is connected to the drain terminal of the selection transistor 51. The gate terminal of the selection transistor 51 is connected to the word line WL. The source terminal of the selection transistor 51 is connected to the bit line / BL.

  A row decoder 52 is connected to the word line WL. A write circuit 54 and a read circuit 55 are connected to the bit line pair BL, / BL. A column decoder 53 is connected to the write circuit 54 and the read circuit 55. Each memory cell MC is selected by the row decoder 52 and the column decoder 53.

  Data is written to the memory cell MC as follows. First, in order to select a memory cell MC for data writing, the word line WL connected to the memory cell MC is activated. As a result, the selection transistor 51 is turned on.

  Here, a bidirectional write current Iw is supplied to the MTJ element 10 in accordance with the write data. Specifically, when the write current Iw is supplied to the MTJ element 10 from left to right, the write circuit 54 applies a positive voltage to the bit line BL and applies a ground voltage to the bit line / BL. When supplying the write current Iw from the right to the left to the MTJ element 10, the write circuit 54 applies a positive voltage to the bit line / BL and applies a ground voltage to the bit line BL. In this way, data “0” or data “1” can be written in the memory cell MC.

  Next, data reading from the memory cell MC is performed as follows. First, the selection transistor 51 of the selected memory cell MC is turned on. The read circuit 55 supplies the MTJ element 10 with a read current Ir that flows from right to left, for example. Then, the read circuit 55 detects the resistance value of the MTJ element 10 based on the read current Ir. In this way, data stored in the MTJ element 10 can be read.

  Next, the structure of the MRAM will be described. FIG. 20 is a cross-sectional view showing the configuration of the MRAM centered on the memory cell MC.

  An element isolation insulating layer is provided in the surface region of the P-type semiconductor substrate 61, and the surface region of the semiconductor substrate 61 in which this element isolation insulating layer is not provided becomes an element area (active area) for forming an element. The element isolation insulating layer is configured by, for example, STI (Shallow Trench Isolation). For example, silicon oxide is used as the STI.

The element region of the semiconductor substrate 61 is provided with a source region S and a drain region D that are separated from each other. Each of the source region S and the drain region D is composed of an N ⁺ type diffusion region formed by introducing a high concentration N ⁺ type impurity into the semiconductor substrate 61. A gate electrode 51B is provided on the semiconductor substrate 61 between the source region S and the drain region D via a gate insulating film 51A. The gate electrode 51B functions as the word line WL. In this way, the selection transistor 51 is provided on the semiconductor substrate 61.

  A wiring layer 63 is provided on the source region S via a contact 62. The wiring layer 63 functions as a bit line / BL.

  On the drain region D, a lead line 65 is provided via a contact 64. An MTJ element 10 sandwiched between the lower electrode 13 and the upper electrode 19 is provided on the lead line 65. A wiring layer 66 is provided on the upper electrode 19. The wiring layer 66 functions as the bit line BL. The space between the semiconductor substrate 61 and the wiring layer 66 is filled with an interlayer insulating layer 67 made of, for example, silicon oxide.

  As described above in detail, the MRAM can be configured using the MTJ element 10 shown in the first embodiment. The MTJ element 10 can be used not only for a spin injection type magnetic memory but also for a domain wall motion type magnetic memory.

  Further, the MRAM shown in the second embodiment can be applied to various devices. Several application examples of MRAM are described below.

(Application example 1)
FIG. 21 shows an extracted DSL data path portion of a digital subscriber line (DSL) modem. The modem includes a programmable digital signal processor (DSP) 100, an analog-digital (A / D) converter 110, a digital-analog (D / A) converter 120, a transmission driver 130, a receiver amplifier 140, and the like. It is configured to include.

  In FIG. 21, the band-pass filter is omitted, and instead, a line code program (encoded subscriber line information executed by the DSP, transmission conditions, etc. (line codes: QAM, CAP, RSK, FM, The MRAM 170 and the EEPROM 180 of this embodiment are shown as various types of optional memories for holding a program for selecting and operating a modem according to AM, PAM, DWMT, etc.).

  In this application example, two types of memories, MRAM 170 and EEPROM 180, are used as memories for holding the line code program. However, EEPROM 180 may be replaced with MRAM. That is, it is possible to use only MRAM instead of using two types of memories.

(Application example 2)
FIG. 22 shows a mobile phone terminal 300 as another application example. A communication unit 200 that realizes a communication function includes a transmission / reception antenna 201, an antenna duplexer 202, a reception unit 203, a baseband processing unit 204, a DSP 205 used as an audio codec, a speaker (receiver) 206, a microphone (transmitter) 207, A transmission unit 208, a frequency synthesizer 209, and the like are provided.

  In addition, the mobile phone terminal 300 is provided with a control unit 220 that controls each unit of the mobile phone terminal. The control unit 220 is a microcomputer formed by connecting a CPU 221, a ROM 222, an MRAM 223 of the present embodiment, and a flash memory 224 via a bus 225. The ROM 222 stores necessary data such as programs executed in the CPU 221 and display fonts.

  The MRAM 223 is mainly used as a work area, and the CPU 221 stores data being calculated during execution of the program as needed, and temporarily stores data exchanged between the control unit 220 and each unit. It is used when doing. Further, the flash memory 224 stores, for example, the immediately previous setting conditions and the like even when the power of the mobile phone terminal 300 is turned off. The setting parameters are stored. Thereby, even if the power of the mobile phone terminal 300 is turned off, the stored setting parameters are not lost.

  Further, the cellular phone terminal 300 is provided with an audio reproduction processing unit 211, an external output terminal 212, an LCD controller 213, a display LCD (liquid crystal display) 214, a ringer 215 that generates a ringing tone, and the like. The audio reproduction processing unit 211 reproduces audio information input to the mobile phone terminal 300 (or audio information stored in an external memory 240 described later). The reproduced audio information can be taken out by transmitting it to headphones or a portable speaker via the external output terminal 212. Thus, by providing the audio reproduction processing unit 211, it is possible to reproduce audio information. The LCD controller 213 receives, for example, display information from the CPU 221 via the bus 225, converts it into LCD control information for controlling the LCD 214, and drives the LCD 214 to perform display.

  The cellular phone terminal 300 is provided with interface circuits (I / F) 231, 233, 235, an external memory 240, an external memory slot 232, a key operation unit 234, an external input / output terminal 236, and the like. An external memory 240 such as a memory card is inserted into the external memory slot 232. The external memory slot 232 is connected to the bus 225 via an interface circuit (I / F) 231. As described above, by providing the slot 232 in the mobile phone terminal 300, information inside the mobile phone terminal 300 is written in the external memory 240, or information (eg, audio information) stored in the external memory 240 is stored in the mobile phone terminal. It is possible to input to 300.

  The key operation unit 234 is connected to the bus 225 via an interface circuit (I / F) 233. Key input information input from the key operation unit 234 is transmitted to the CPU 221, for example. The external input / output terminal 236 is connected to the bus 225 via an interface circuit (I / F) 233, and inputs various information from the outside to the mobile phone terminal 300, or sends information from the mobile phone terminal 300 to the outside. It functions as a terminal for output.

  In this application example, the ROM 222, the MRAM 223, and the flash memory 224 are used. However, the flash memory 224 may be replaced with an MRAM, and the ROM 222 may be replaced with an MRAM.

(Application example 3)
FIGS. 23 to 27 show examples in which the MRAM is applied to a card (MRAM card) that stores media contents such as smart media.

  As shown in FIG. 23, an MRAM chip 401 is built in the MRAM card main body 400. In the card body 400, an opening 402 is formed at a position corresponding to the MRAM chip 401, and the MRAM chip 401 is exposed. The opening 402 is provided with a shutter 403 so that the MRAM chip 401 is protected by the shutter 403 when the MRAM card is carried. The shutter 403 is made of a material having an effect of shielding an external magnetic field, for example, ceramic. When transferring data, the shutter 403 is opened and the MRAM chip 401 is exposed. The external terminal 404 is for taking out content data stored in the MRAM card to the outside.

  24 and 25 show a top view and a cross-sectional view of a card insertion type transfer device 500 for transferring data to the MRAM card.

  The data transfer device 500 includes a storage unit 500a. The storage unit 500a stores the first MRAM card 550. The storage unit 500 a is provided with an external terminal 530 that is electrically connected to the first MRAM card 550, and the data of the first MRAM card 550 is rewritten using the external terminal 530.

  The second MRAM card 450 used by the end user is inserted from the insertion portion 510 of the transfer device 500 as indicated by an arrow, and is pushed in until it stops at the stopper 520. The stopper 520 also functions as a member for aligning the first MRAM 550 and the second MRAM card 450. When the second MRAM card 450 is arranged at a predetermined position, a control signal is supplied from the first MRAM data rewrite control unit to the external terminal 530, and the data stored in the first MRAM 550 is transferred to the second MRAM card 450.

  FIG. 26 shows a fitting type transfer device. This transfer device is a type that is placed so as to fit the second MRAM card 450 on the first MRAM 550 with the stopper 520 as a target, as indicated by an arrow. Since the transfer method is the same as that of the card insertion type, the description is omitted.

  FIG. 27 shows a slide type transfer device. In this transfer device, similarly to the CD-ROM drive and DVD drive, a tray slide 560 is provided in the transfer device 500, and the tray slide 560 moves as indicated by an arrow. When the tray slide 560 moves to the position of the broken line, the second MRAM card 450 is placed on the tray slide 560 and the second MRAM card 450 is conveyed into the transfer device 500. The point that the tip of the second MRAM card 450 is brought into contact with the stopper 520 and the transfer method are the same as those of the card insertion type, and thus the description thereof is omitted.

  The present invention is not limited to the above-described embodiment, and can be embodied by modifying the components without departing from the scope of the invention. In addition, various inventions can be configured by appropriately combining a plurality of constituent elements disclosed in the embodiments. For example, some constituent elements may be deleted from all the constituent elements disclosed in the embodiments, or constituent elements of different embodiments may be appropriately combined.

The figure which shows the relationship between a damping constant and the composition of a Co-Fe alloy. The figure which shows the relationship between a damping constant and a composition of Pd-Au alloy. The figure which shows the relationship between a magnetic anisotropic energy density and a composition of a Pd-Au alloy. FIG. 3 is a cross-sectional view showing the configuration of the GMR element according to the first embodiment. The figure which shows the MR-H curve of the GMR element shown in FIG. Sectional drawing of the MTJ structure which concerns on 1st Embodiment. 1 is a schematic view of an MTJ element 10 having a single pin structure according to a first embodiment. Sectional drawing which shows the structure of the MTJ element 10 which concerns on the specific example 1-1. 1 is a schematic diagram of an MTJ element 10 having a dual pin structure according to a first embodiment. Sectional drawing which shows the structure of the MTJ element 10 concerning the specific example 2-1. Sectional drawing which shows the structure of the MTJ element 10 concerning the specific example 2-2. Sectional drawing which shows the structure of the MTJ element 10 concerning the specific example 2-3. Sectional drawing which shows the structure of the MTJ element 10 of the specific example 2-4. Sectional drawing which shows the structure of the MTJ element 10 of the specific example 2-5. The figure explaining the other structural example of the fixed layer 22. FIG. The figure explaining the other structural example of the fixed layer 22. FIG. The figure explaining the other structural example of the fixed layer 22. FIG. The figure explaining the other structural example of the fixed layer 22. FIG. The circuit diagram which shows the structure of MRAM which concerns on the 2nd Embodiment of this invention. FIG. 3 is a cross-sectional view showing a configuration of an MRAM centered on a memory cell MC. The block diagram which shows the DSL data path part of the modem for digital subscriber lines (DSL) based on the application example 1 of MRAM. The block diagram which shows the mobile telephone terminal 300 which concerns on the application example 2 of MRAM. The top view which shows the MRAM card | curd 400 which concerns on the application example 3 of MRAM. The top view which shows the transfer apparatus 500 for transferring data to an MRAM card. Sectional drawing which shows the transfer apparatus 500 for transferring data to an MRAM card. FIG. 3 is a cross-sectional view showing a fitting type transfer device 500 for transferring data to an MRAM card. Sectional drawing which shows the slide-type transfer apparatus 500 for transferring data to an MRAM card.

  DESCRIPTION OF SYMBOLS 10 ... MTJ element, 11 ... Substrate, 12 ... Low resistance layer, 13 ... Adhesion layer (lower electrode), 14 ... Underlayer, 15 ... Fixed layer, 15A ... Interface layer, 16 ... Tunnel barrier layer, 17 ... Recording layer, 17A ... magnetic layer, 17B ... nonmagnetic layer, 18 ... protective layer, 19 ... hard mask (upper electrode), 21 ... spacer layer, 22 ... fixed layer, 22-1, 22-3 ... magnetic layer, 22-2 ... Nonmagnetic layer, 50 ... memory cell array, 51 ... select transistor, 51A ... gate insulating film, 51B ... gate electrode, 52 ... row decoder, 53 ... column decoder, 54 ... write circuit, 55 ... read circuit, 61 ... semiconductor substrate, 62, 64 ... contact, 63, 66 ... wiring layer, 65 ... lead-out line, 67 ... interlayer insulating layer, MC ... memory cell, BL ... bit line, WL ... word line, S ... source region, D ... drain region , 100 ... DSP, 110 ... A / D converter, 120 ... D / A converter, 130 ... transmission driver, 140 ... receiver amplifier, 170 ... MRAM, 180 ... EEPROM, 200 ... communication unit, 201 ... transmission / reception antenna, 202 ... Antenna duplexer 203 ... receiving unit 204 ... baseband processing unit 205 ... DSP, 206 ... speaker, 207 ... microphone, 208 ... transmitting unit, 209 ... frequency synthesizer, 211 ... audio reproduction processing unit, 212 ... external output terminal 213 ... LCD controller, 214 ... LCD, 215 ... linger, 220 ... control unit, 221 ... CPU, 222 ... ROM, 223 ... MRAM, 224 ... flash memory, 225 ... bus, 231,233,235 ... interface circuit, 232 ... External memory slot, 232 ... 234 ... Key operation unit, 236 ... External input / output terminal, 240 ... External memory, 300 ... Mobile phone terminal, 400 ... MRAM card body, 401 ... MRAM chip, 402 ... Opening, 403 ... Shutter, 404 ... External Terminals, 450 ... MRAM card, 500 ... transfer device, 510 ... insertion section, 520 ... stopper, 530 ... external terminal, 550 ... MRAM, 560 ... dish slide.

Claims (20)

A first fixed layer having magnetic anisotropy perpendicular to the film surface and having a fixed magnetization direction;
A recording layer having a laminated structure in which magnetic layers and nonmagnetic layers are alternately laminated, having a magnetic anisotropy perpendicular to the film surface, and capable of changing the magnetization direction;
A first intermediate layer provided between the first fixed layer and the recording layer and made of a nonmagnetic material;
Of the magnetic layers constituting the recording layer, the first magnetic layer in contact with the first intermediate layer is made of an alloy containing cobalt (Co) and iron (Fe), and the film thickness thereof is the first intermediate layer. A magnetoresistive element having a thickness greater than that of a magnetic layer not in contact with the layer. Claim wherein at least one layer of the magnetic layers constituting the recording layer, which consists of an alloy _{Co 100-x} -Fe x containing cobalt (Co) and iron (Fe), characterized in that it is a x ≧ 20at% 1. The magnetoresistive element according to 1. It said first magnetic layer is comprised of cobalt (Co), iron (Fe), and an alloy _{(Co 100-x -Fe x)} 100-y B y containing boron (B), x ≧ 20at% , 0 < The magnetoresistive element according to claim 1, wherein y ≦ 30 at%. The first magnetic layer is made of an alloy containing cobalt (Co) and having a composition of Co ₂ XY, where X is vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni) and one or more elements of copper (Cu), Y is aluminum (Al), gallium (Ga), indium (In), silicon (Si), germanium (Ge), tin (Sn) And at least one element selected from antimony (Sb).   5. The magnetoresistive element according to claim 1, wherein at least one of the nonmagnetic layers constituting the recording layer is made of an alloy containing palladium (Pd) and gold (Au).   6. The magnetoresistance according to claim 1, wherein a nonmagnetic layer farthest from the first intermediate layer among the nonmagnetic layers constituting the recording layer is made of gold (Au). element.   The magnetoresistive element according to claim 1, wherein the first intermediate layer has a NaCl structure and is oriented in a (100) plane.   The magnetoresistive element according to claim 1, wherein the first intermediate layer is made of magnesium oxide.   9. The magnetoresistive element according to claim 1, wherein the first magnetic layer has a cubic structure or a tetragonal structure, and is oriented in a (100) plane. Said first pinned layer, the magnetoresistive element according to any one of claims 1 to 9, characterized in that it comprises a ferromagnetic alloy having an L1 ₀ structure.   The first fixed layer includes one or more elements of iron (Fe), cobalt (Co), and nickel (Ni), and one or more elements of palladium (Pd) and platinum (Pt). The magnetoresistive element according to claim 1, comprising: Further comprising an interface layer provided between the first fixed layer and the first intermediate layer;
The interfacial layer is comprised of cobalt (Co), iron (Fe), and alloys containing boron _{(B) (Co 100-x} -Fe x) consists _{100-y B y, x ≧} 20at%, 0 <y ≦ 30at The magnetoresistive element according to claim 1, wherein the magnetoresistive element is%.   The magnetoresistive element according to claim 12, wherein the interface layer has a cubic structure or a tetragonal structure and is oriented in a (100) plane. A second pinned layer having magnetic anisotropy perpendicular to the film surface and having a fixed magnetization direction;
12. The magnetism according to claim 1, further comprising a second intermediate layer provided between the second pinned layer and the recording layer and made of a nonmagnetic material. Resistance element.   The magnetoresistive element according to claim 14, wherein the second intermediate layer is made of gold (Au). At least one of the first pinned layer and the second pinned layer is between the second magnetic layer, the third magnetic layer, and the second magnetic layer and the third magnetic layer. And a first nonmagnetic layer provided on
The magnetoresistive element according to claim 14 or 15, wherein the second magnetic layer and the third magnetic layer are antiferromagnetically coupled to each other.   The first nonmagnetic layer includes a metal composed of one element out of ruthenium (Ru), osmium (Os), rhenium (Re), and rhodium (Rh), or at least one of these elements. The magnetoresistive element according to claim 16, which is made of an alloy.   18. The magnetoresistive element according to claim 1, and first and second electrodes provided so as to sandwich the magnetoresistive element and energizing the magnetoresistive element. A magnetic memory comprising a memory cell. A first wiring electrically connected to the first electrode;
A second wiring electrically connected to the second electrode;
The magnetic circuit according to claim 18, further comprising a writing circuit electrically connected to the first wiring and the second wiring and supplying a current to the magnetoresistive element bidirectionally. memory.   The magnetic memory according to claim 19, wherein the memory cell includes a selection transistor electrically connected between the second electrode and the write circuit.

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