JP2010177218A - Tunnel type magnetic detection element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tunnel type magnetic detection element which can increase a resistance change ratio (ΔR/R) as compared to the conventional technique while especially suppressing increase of magnetic distortion λs of a free magnetic layer. <P>SOLUTION: An insulation barrier layer 5 is formed of Mg-O. The free magnetic layer 6 is constituted of an enhance layer 12, a first soft magnetic layer 13, a Co-Ta layer 14, and a second soft magnetic layer 15 which are layered from bottom in this order. Thus, by inserting the Co-Ta layer 14 between the soft magnetic layers 13 and 15, it is possible to increase the resistance change ratio (ΔR/R) as compared to the conventional technique while suppressing increase of magnetic distortion λs of the free magnetic layer 6. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  In particular, the present invention relates to a tunneling magnetic sensing element capable of increasing the rate of change in resistance (ΔR / R) as compared with the prior art while suppressing an increase in magnetostriction λs of a free magnetic layer.

  A tunnel-type magnetic sensing element (TMR element) changes its resistance by utilizing the tunnel effect. When the magnetization of the pinned magnetic layer and the magnetization of the free magnetic layer are antiparallel, the pinned magnetic layer and the free magnetic layer When the tunneling current hardly flows through the insulating barrier layer provided between the layers and the resistance value is maximized, the magnetization of the pinned magnetic layer and the magnetization of the free magnetic layer are most The tunnel current easily flows and the resistance value is minimized.

Using this principle, the electric resistance that changes due to the fluctuation of the magnetization of the free magnetic layer under the influence of an external magnetic field is detected as a voltage change, and a leakage magnetic field from the recording medium is detected.
JP 2000-101164 A JP-A-10-261824 Japanese Patent Laid-Open No. 10-154111 JP-A-8-167120

  When Mg—O (magnesium oxide) is used for the insulating barrier layer of the tunneling magnetic sensing element, the rate of change in resistance (ΔR / R) compared to the case where the insulating barrier layer is formed of Al—O or Ti—O. It is known that can be increased.

  However, in order to cope with the higher recording density, it is necessary to further increase the rate of change in resistance (ΔR / R).

  For example, as shown in an experiment to be described later, when a Ta layer is inserted into a Ni—Fe layer constituting the free magnetic layer, the rate of change in resistance (ΔR / R) is increased as compared with a configuration in which the Ta layer is not inserted. I understood it.

  However, since the magnetostriction λs of the free magnetic layer becomes very large due to the insertion of the Ta layer, there is a problem that the reproduction characteristics become unstable.

  In each of the above-mentioned patent documents, in the tunnel type magnetic sensing element using Mg—O (magnesium oxide) as the insulating barrier layer, the increase in the magnetostriction λs of the free magnetic layer is suppressed to a smaller value than the conventional one. The structure of the free magnetic layer for increasing the rate of change (ΔR / R) is not disclosed.

  Therefore, the present invention is to solve the above-described conventional problems, and in particular, it is possible to increase the rate of resistance change (ΔR / R) as compared with the conventional one while suppressing an increase in magnetostriction λs of the free magnetic layer. An object of the present invention is to provide a tunneling magnetic sensing element that can be used.

The tunneling magnetic sensing element of the present invention includes a pinned magnetic layer whose magnetization direction is fixed from the bottom, an insulating barrier layer, and a free magnetic layer whose magnetization direction varies with respect to an external magnetic field, or the free magnetic layer from below. A magnetic layer, the insulating barrier layer, and a laminate including a laminated portion laminated in order of the pinned magnetic layer;
The insulating barrier layer is formed of Mg-O;
The free magnetic layer includes a soft magnetic layer and an enhancement layer positioned between the soft magnetic layer and the insulating barrier layer and having a higher spin polarizability than the soft magnetic layer,
In the soft magnetic layer, a Co—Ta layer is inserted in a plane direction parallel to the interface of each layer constituting the laminate, and the soft magnetic layer has a film thickness through the Co—Ta layer. It is divided into a plurality of layers in the direction.

  This effectively increases the rate of change in resistance (ΔR / R) compared to the prior art while minimizing the increase in magnetostriction λs of the free magnetic layer in the tunnel type magnetic sensing element in which the insulating barrier layer is made of Mg—O. Can be made. The term “conventional” as used herein refers to a tunneling magnetic sensing element in which a Co—Ta layer is not provided in a free magnetic layer, and the free magnetic layer is a laminated structure of an enhancement layer and a soft magnetic layer, unlike the present invention. .

  In the present invention, it is preferable that the Ta composition ratio X of the Co—Ta layer is 10 at% or more and 40 at% or less because the Co—Ta layer can be formed of an amorphous magnetic layer.

  In the present invention, the average film thickness of the Co—Ta layer is preferably in the range of 2 to 20 mm. Thus, when compared with the comparative example in which the Ta layer is inserted in the soft magnetic layer, in the present invention, when the resistance change rate (ΔR / R) equivalent to the comparative example can be obtained, the magnetostriction is lower than that of the comparative example. When λs can be realized or magnetostriction λs equivalent to that of the comparative example can be obtained, a higher resistance change rate (ΔR / R) than that of the comparative example can be realized.

  In the present invention, the average film thickness of the Co—Ta layer is preferably in the range of 2 to 14 mm. Even if the average film thickness of the Co—Ta layer is thicker than 14 mm, the effect of increasing the rate of change in resistance (ΔR / R) remains unchanged, and the magnetostriction λs tends to increase slightly. Further, increasing the average film thickness of the Co—Ta layer increases the gap length (GL) between the upper and lower shield layers. Therefore, the preferable upper limit of the average film thickness of the Co—Ta layer is set to 14 mm.

  In the present invention, the average film thickness of the Co—Ta layer is preferably in the range of 10 to 14 mm. Thereby, in the comparative example in which the Ta layer is inserted in the soft magnetic layer, the present invention is higher than the comparative example in comparison with the case where the Ta film thickness with the largest resistance change rate (ΔR / R) is selected. A resistance change rate (ΔR / R) can be obtained, and a low magnetostriction λs can be realized as compared with the comparative example.

  In the present invention, the average film thickness of the Co—Ta layer is preferably in the range of 2 to 8 mm. As a result, the rate of change in resistance (ΔR / R) of the present invention tends to be smaller than that of the comparative example in which the Ta layer is inserted in the soft magnetic layer, but the magnetostriction λs of the free magnetic layer is more reliably set than in the comparative example. Can be small. Therefore, it is possible to increase the rate of change in resistance (ΔR / R) more than before while suppressing the increase in magnetostriction λs of the free magnetic layer more effectively.

  In the present invention, the soft magnetic layer is made of Ni-Fe, and the enhancement layer is made of Co-Fe, so that the soft magnetic characteristics of the free magnetic layer can be kept good and the resistance change rate ( ΔR / R) can be increased, which is preferable.

  In the present invention, it is preferable that the pinned magnetic layer, the insulating barrier layer, and the free magnetic layer are laminated in this order from the bottom in order to effectively obtain a high rate of change in resistance (ΔR / R). is there.

  In the present invention, in the tunnel type magnetic sensing element in which the insulating barrier layer is formed of Mg—O, the resistance change rate (ΔR / R) is effectively reduced as compared with the conventional one while suppressing an increase in the magnetostriction λs of the free magnetic layer. Can be increased.

  FIG. 1 is a cross-sectional view of the tunnel type magnetic sensing element of the present embodiment cut along a plane parallel to the surface facing the recording medium, and FIG. 2 is mainly a free magnetism of the tunnel type magnetoresistive effect element shown in FIG. It is the elements on larger scale which expanded the part of the layer. In FIG. 1, the free magnetic layer is illustrated as having a single layer structure, but in actuality, it is formed in the laminated structure shown in FIG.

  The tunnel-type magnetic detection element is provided, for example, at the trailing end of a floating slider provided in a hard disk device, and detects a leakage magnetic field (recording magnetic field) from a magnetic recording medium. In the figure, the X direction is the track width direction, the Y direction is the direction of the leakage magnetic field from the magnetic recording medium (height direction), and the Z direction is the moving direction of the magnetic recording medium and each layer of the tunnel type magnetic sensing element. Is the stacking direction.

  The lowermost layer in FIG. 1 is a lower shield layer 21 made of, for example, Ni—Fe. A laminate 10 is formed on the lower shield layer 21. The tunnel-type magnetic detection element includes the stacked body 10, and an insulating layer 22, a hard bias layer 23, and a protective layer 24 formed on both sides of the stacked body 10 in the track width direction (X direction in the drawing). Configured.

  The lowermost layer of the laminate 10 is an underlayer 1 formed of one or more nonmagnetic elements among Ta, Hf, Nb, Zr, Ti, Mo, and W. A seed layer 2 is provided on the base layer 1. The seed layer 2 is formed of Ni—Fe—Cr, Cr, or Ru. The underlayer 1 may not be formed.

  The antiferromagnetic layer 3 formed on the seed layer 2 includes an element α (where α is one or more of Pt, Pd, Ir, Rh, Ru, and Os) and Mn. It is preferable to form with the antiferromagnetic material containing these.

  The antiferromagnetic layer 3 includes an element α and an element α ′ (where the element α ′ is Ne, Ar, Kr, Xe, Be, B, C, N, Mg, Al, Si, P, Ti, V, One or two of Cr, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, Cd, Sn, Hf, Ta, W, Re, Au, Pb, and rare earth elements It may be formed of an antiferromagnetic material containing the above elements) and Mn.

The antiferromagnetic layer 3 is made of, for example, Ir—Mn.
A pinned magnetic layer 4 is formed on the antiferromagnetic layer 3. The pinned magnetic layer 4 has a laminated ferrimagnetic structure in which a first pinned magnetic layer 4a, a nonmagnetic intermediate layer 4b, and a second pinned magnetic layer 4c are laminated in this order from the bottom. The first pinned magnetic layer 4a and the second pinned magnetic layer 4a are coupled to the second pinned magnetic layer 4a by the exchange coupling magnetic field (Hex) at the interface with the antiferromagnetic layer 3 and the antiferromagnetic exchange coupling magnetic field (RKKY interaction) via the nonmagnetic intermediate layer 4b. The magnetization directions of the pinned magnetic layer 4c are antiparallel to each other. By forming the pinned magnetic layer 4 with a laminated ferrimagnetic structure, the magnetization of the pinned magnetic layer 4 can be stabilized. The exchange coupling magnetic field generated at the interface between the pinned magnetic layer 4 and the antiferromagnetic layer 3 can be apparently increased. The first pinned magnetic layer 4a and the second pinned magnetic layer 4c are each formed of, for example, about 10 to 40 mm, and the nonmagnetic intermediate layer 4b is formed of about 8 to 10 mm.

  The first pinned magnetic layer 4a is formed of a ferromagnetic material such as Co—Fe, Ni—Fe, or Co—Fe—Ni. The second pinned magnetic layer 4c can be formed of the same material as the first pinned magnetic layer 4a, but more preferable materials will be described later. The nonmagnetic intermediate layer 4b is formed of a nonmagnetic conductive material such as Ru, Rh, Ir, Cr, Re, or Cu.

An insulating barrier layer 5 made of Mg—O (magnesium oxide) is formed on the pinned magnetic layer 4. Mg—O preferably has an Mg composition ratio in the range of 40 to 60 at%, and most preferably Mg _{50 at%} O _{50 at%} .

  A free magnetic layer 6 is formed on the insulating barrier layer 5. The configuration of the free magnetic layer 6 will be described later.

The track width Tw is determined by the width dimension of the free magnetic layer 6 in the track width direction (X direction in the drawing).
A protective layer 7 made of Ta or the like is formed on the free magnetic layer 6.

  Both side end surfaces 11, 11 in the track width direction (X direction in the drawing) of the laminate 10 are formed as inclined surfaces so that the width dimension in the track width direction gradually decreases from the lower side toward the upper side.

  As shown in FIG. 1, an insulating layer 22 is formed from the lower shield layer 21 spreading on both sides of the laminated body 10 to both side end surfaces 11 of the laminated body 10, and a hard bias layer 23 is formed on the insulating layer 22. Further, a protective layer 24 is formed on the hard bias layer 23. The protective layer 24 is made of a nonmagnetic material such as Ta.

  A bias underlayer (not shown) may be formed between the insulating layer 22 and the hard bias layer 23. The bias underlayer is formed of Cr, W, Ti, or the like.

The insulating layer 22 is made of an insulating material such as Al ₂ O ₃ or SiO ₂ . The insulating layer 22 insulates under the hard bias layer 23 so as to suppress the current flowing in the stack 10 in the direction perpendicular to the interface between the layers from being shunted to both sides of the stack 10 in the track width direction. To do. The hard bias layer 23 is made of, for example, Co—Pt or Co—Cr—Pt.

  An upper shield layer 26 made of Ni—Fe or the like is formed on the laminate 10 and the protective layer 24.

  In the embodiment shown in FIG. 1, the lower shield layer 21 and the upper shield layer 26 function as electrode layers for the stacked body 10, and are perpendicular to the film surface of each layer of the stacked body 10 (parallel to the Z direction in the drawing). Direction).

  The free magnetic layer 6 is magnetized in a direction parallel to the track width direction (X direction in the drawing) by receiving a bias magnetic field from the hard bias layer 23. On the other hand, the first pinned magnetic layer 4a and the second pinned magnetic layer 4c constituting the pinned magnetic layer 4 are magnetized in a direction parallel to the height direction (Y direction in the drawing). Since the pinned magnetic layer 4 has a laminated ferrimagnetic structure, the first pinned magnetic layer 4a and the second pinned magnetic layer 4c are magnetized antiparallel. The magnetization of the fixed magnetic layer 4 is fixed (the magnetization does not fluctuate due to an external magnetic field), but the magnetization of the free magnetic layer 6 fluctuates due to an external magnetic field.

  When the magnetization of the free magnetic layer 6 is fluctuated by an external magnetic field, the magnetization is provided between the second pinned magnetic layer 4c and the free magnetic layer 6 when the magnetizations of the second pinned magnetic layer 4c and the free magnetic layer are antiparallel. The tunnel current is less likely to flow through the insulating barrier layer 5 and the resistance value is maximized. On the other hand, when the magnetizations of the second pinned magnetic layer 4c and the free magnetic layer 6 are parallel, the tunnel current flows most easily and the resistance value is minimized.

  Using this principle, the electric resistance that changes due to the fluctuation of the magnetization of the free magnetic layer 6 under the influence of an external magnetic field is regarded as a voltage change, and a leakage magnetic field from the magnetic recording medium is detected. Yes.

The characteristic part of the tunnel type magnetic detection element in this embodiment will be described below.
As shown in FIG. 2, the free magnetic layer 6 is laminated in order of an enhancement layer 12, a first soft magnetic layer 13, a Co—Ta layer 14, and a second soft magnetic layer 15 from the bottom.

  The enhancement layer 12 is preferably made of a magnetic material having a higher spin polarizability than the first soft magnetic layer 13 and the second soft magnetic layer 15, and the enhancement layer 12 is preferably made of Co—Fe. It is. It is known that if the enhancement layer 12 is not formed, the rate of change in resistance (ΔR / R) is greatly reduced. Therefore, the enhancement layer 12 is an essential layer. A high resistance change rate (ΔR / R) can be obtained by increasing the Fe concentration of Co—Fe constituting the enhancement layer 12. The Fe concentration of Co—Fe is preferably in the range of 25 at% to 100 at%. More preferably, the upper limit of the Fe concentration is 80 at%.

  The first soft magnetic layer 13 and the second soft magnetic layer 15 are materials excellent in soft magnetic properties such as a lower coercive force and a lower anisotropic magnetic field than the enhancement layer 12. The first soft magnetic layer 13 and the second soft magnetic layer 15 may be formed of different soft magnetic materials, but are preferably formed of Ni-Fe. The Fe concentration of Ni—Fe is preferably in the range of 10 at% to 20 at%.

  The Co—Ta layer 14 is formed so that the first soft magnetic layer 13, the second soft magnetic layer 15, and the like are oriented in a plane direction (XY plane direction) parallel to the interface of each layer constituting the stacked body 10. Is inserted between.

  Conventionally, for example, the free magnetic layer 6 has a configuration in which an enhancement layer 12 and a soft magnetic layer are laminated. In the present embodiment, the Co—Ta layer 14 is inserted into the soft magnetic layer, so that the soft magnetic layer 6 is The layers are divided into the first soft magnetic layer 13 and the second soft magnetic layer 15 in the film thickness direction via the Co—Ta layer 14, and the soft magnetic layers 13 and 15 are formed with a small film thickness.

  Here, the first soft magnetic layer 13 and the second soft magnetic layer 15 are not only completely (continuously) separated by the Co—Ta layer 14 but also intermittently separated. Including. For example, when the Co—Ta layer 14 is formed thin and pinholes are formed in the Co—Ta layer 14, the first soft magnetic layer 13 and the second soft magnetic layer are formed in the pinhole portion. Although the layer 15 contacts, such a form is also included. However, the rate of change in resistance (ΔR / R) is that the first soft magnetic layer 13 and the second soft magnetic layer 15 are completely (continuously) divided by the Co—Ta layer 14. It is suitable for increasing the value.

  In the tunnel magnetoresistive effect element in which the insulating barrier layer 5 is formed of Mg—O as in the present embodiment, the second pinned magnetic layer 4c / insulating barrier layer 5 / enhancement layer 12 are connected to the interface (XY plane). The resistance change rate (ΔR / R) is formed in a body-centered cubic structure (bcc structure) in which equivalent crystal planes typically represented as {100} planes are preferentially oriented in a plane direction parallel to It is important in improving.

  By the way, the Ni—Fe soft magnetic layer formed on the enhancement layer 12 is preferentially oriented in an equivalent crystal plane typically represented as a {111} plane in a plane direction parallel to the interface (XY plane). The face-centered cubic structure (fcc structure) is formed. For this reason, in the conventional structure in which a thick single-layer soft magnetic layer (Ni—Fe) is provided on the enhancement layer 12, the crystal structure of the enhancement layer 12 has a soft magnetic layer ( Crystal distortion is likely to occur due to the influence of the crystal structure of (Ni—Fe).

  On the other hand, in this embodiment, a Co—Ta layer 14 is interposed between the soft magnetic layers 13 and 15. Therefore, the film thickness of the first soft magnetic layer 13 in contact with the enhancement layer 12 is such that the first soft magnetic layer 13 and the second soft magnetic layer 15 are integrated without forming the Co—Ta layer 14. Can be thinner. Therefore, the crystal orientation of the first soft magnetic layer 13 itself in contact with the enhancement layer 12 can be weakened. Moreover, the Co—Ta layer 14 is an amorphous magnetic layer. Therefore, the crystal orientation between the second soft magnetic layer 15 and the first soft magnetic layer 13 is divided at the Co—Ta layer 14 portion. As a result, the influence of the soft magnetic layer on the crystal structure of the enhancement layer 12 can be weakened.

  Further, when Co—Ta having a negative magnetostriction λs in bulk is inserted as a Co—Ta layer 14 into the soft magnetic layer of the free magnetic layer 6, the conventional Co—Ta layer 14 is not inserted as shown in the experimental results described later. The magnetostriction λs of the free magnetic layer 6 is slightly larger than that of the example, but the increase in the magnetostriction λs of the free magnetic layer 6 is suppressed in this embodiment as compared with the comparative example in which the Ta layer is inserted in the soft magnetic layer. it can.

  As described above, in the present embodiment, the enhancement layer 12 is effectively represented on the insulating barrier layer 5 made of Mg—O, in a plane direction parallel to the interface (XY plane), typically { 100} planes can be formed with a body-centered cubic structure (bcc structure) in which equivalent crystal planes are preferentially oriented, and the rate of change in resistance (ΔR / R) is suppressed while suppressing an increase in magnetostriction λs of the free magnetic layer 6. Can be increased compared to the prior art.

  In addition, in the present embodiment, the total thickness obtained by adding the average thickness T2 of the first soft magnetic layer 13 and the average thickness T4 of the second soft magnetic layer 15 is a conventional soft magnetic layer formed as a single layer. Since the film thickness can be made equal to the film thickness, the soft magnetic characteristics of the free magnetic layer can be kept good.

  In the present embodiment, the Ta composition ratio X of the Co—Ta layer 14 is preferably 10 at% or more and 40 at% or less. Thereby, the Co—Ta layer 14 can be formed of an amorphous magnetic layer, and the resistance change rate (ΔR / R) can be effectively increased.

  In the present embodiment, the average film thickness T3 of the Co—Ta layer 14 is preferably in the range of 2 to 20 mm. Thereby, when comparing the comparative example in which the Ta layer is inserted in the soft magnetic layer and the present embodiment in which the Co—Ta layer 14 is inserted in the soft magnetic layer, the present embodiment and the comparative example are equivalent in magnetostriction. When λs can be obtained, the resistance change rate (ΔR / R) of the present embodiment can be increased as compared with the comparative example, or the resistance change rate (ΔR / R) of the present embodiment and the comparative example is equivalent. In this embodiment, the magnetostriction λs can be reduced compared to the comparative example.

  In this embodiment, the average film thickness T3 of the Co—Ta layer 14 is preferably in the range of 2 to 14 mm. Even if the average film thickness T3 of the Co—Ta layer 14 is thicker than 14 mm, the effect of increasing the rate of change in resistance (ΔR / R) remains the same, but rather the magnetostriction λs tends to increase slightly. Further, by increasing the average film thickness T3 of the Co—Ta layer 14, the gap length (GL) determined by the distance between the lower shield layer 21 and the upper shield layer 26 (= film thickness of the laminated body 10) increases. End up. Therefore, a preferable upper limit value of the average film thickness T3 of the Co—Ta layer 14 is set to 14 mm.

  In the present embodiment, the average film thickness T3 of the Co—Ta layer 14 is preferably in the range of 10 to 14 mm. Thereby, in the comparative example in which the Ta layer is inserted in the soft magnetic layer, the present embodiment is more effective than the comparative example in comparison with the case where the Ta film thickness with the largest resistance change rate (ΔR / R) is selected. A high resistance change rate (ΔR / R) can be obtained, and a low magnetostriction λs can be realized as compared with the comparative example.

  Or in this embodiment, it is preferable that the average film thickness T3 of the said Co-Ta layer 14 exists in the range of 2 to 8 mm. Thereby, although the resistance change rate (ΔR / R) of the present embodiment is likely to be smaller than that of the comparative example in which the Ta layer is inserted in the soft magnetic layer, the magnetostriction λs of the free magnetic layer 6 is smaller than that of the comparative example. Can be surely small. Therefore, it is possible to increase the rate of change in resistance (ΔR / R) more than before, while suppressing the increase in magnetostriction λs of the free magnetic layer 6 more effectively.

  Since the Co—Ta layer 14 is a magnetic material, the first soft magnetic layer 13 / Co—Ta layer 14 / second soft magnetic layer even if the average film thickness T3 of the Co—Ta layer 14 is increased. The 15 stacked portions are magnetically coupled. That is, for example, in a comparative example in which a nonmagnetic Ta layer is inserted between the first soft magnetic layer 13 and the second soft magnetic layer 15, when the thickness of the Ta layer is approximately 5 mm or more, Since the magnetic coupling between the magnetic layer 13 and the second soft magnetic layer 15 is easily broken and there is a problem in the stability of reproduction characteristics, it is considered necessary to make the thickness of the Ta layer very thin. In this embodiment, it is possible to make the average film thickness T3 of the Co—Ta layer 14 larger than, for example, 5 mm without considering the disconnection of the magnetic coupling. Therefore, in the present embodiment, the average film thickness T3 of the preferred Co—Ta layer 14 can be defined without considering the disconnection of the magnetic coupling.

  As shown in FIG. 2, the average thickness of the enhancement layer 12 is T1, the average thickness of the first soft magnetic layer 13 is T2, and the average thickness of the second soft magnetic layer 15 is T4. is there.

  In order to effectively increase the rate of change in resistance (ΔR / R), the average film thickness T1 of the enhancement layer 12 is preferably 2 to 30 mm. The average film thickness T1 of the enhancement layer 12 is more preferably 10 to 30 mm.

The average thickness T2 of the first soft magnetic layer 13 is preferably 5 mm or more and 30 mm or less. The average thickness T2 of the first soft magnetic layer 13 is more preferably 15 mm or more and 25 mm or less. Thereby, it is possible to effectively increase the resistance change rate (ΔR / R).
By providing the first soft magnetic layer 13 between the enhancement layer 12 and the Co—Ta layer 14, diffusion of Ta into the insulating barrier layer 17 can be suppressed, thereby increasing the rate of change in resistance (R / R). Can be expected.

  The average film thickness T4 of the second soft magnetic layer 15 is adjusted so that the total film thickness combined with the average film thickness T2 of the first soft magnetic layer 13 is in the range of 40 mm to 70 mm. Thereby, the soft magnetic characteristics represented by the coercive force Hc of the free magnetic layer 6 can be kept good.

  In the form shown in FIGS. 1 and 2, the antiferromagnetic layer 3, the pinned magnetic layer 4, the insulating barrier layer 5, the free magnetic layer 6 and the protective layer 7 are stacked in this order from the bottom. The layer 6, the insulating barrier layer 5, the pinned magnetic layer 4, the antiferromagnetic layer 3, and the protective layer 7 may be laminated in this order.

  In this case, as shown in FIG. 3, the free magnetic layer 6 is laminated in order of the second soft magnetic layer 15, the Co—Ta layer 14, the first soft magnetic layer 13 and the enhancement layer 12 from the bottom. An insulating barrier layer 5 is formed on the layer 6. The thickness and material of each layer constituting the free magnetic layer 6 are as described above.

  Alternatively, the lower antiferromagnetic layer, the lower pinned magnetic layer, the lower insulating barrier layer, the free magnetic layer, the upper insulating barrier layer, the upper pinned magnetic layer, and the upper antiferromagnetic layer are sequentially stacked from the bottom. A dual-type tunneling magnetic detection element may be used.

  In this case, as shown in FIG. 4, the free magnetic layer 6 is laminated in order of the enhancement layer 12, the soft magnetic layer 28, the Co—Ta layer 14, the soft magnetic layer 25, and the enhancement layer 27 from the bottom. The lower insulating barrier layer 17 is formed below the enhancement layer 12 below the free magnetic layer 6, and the upper insulating barrier layer 18 is formed on the enhancement layer 27 above the free magnetic layer 6. . The film thickness and material of each layer constituting the free magnetic layer 6 are as described above. The soft magnetic layers 25 and 28 are both formed with the same film thickness as the first soft magnetic layer 13 shown in FIG.

  In each of the embodiments shown in FIGS. 2 to 4, the Co—Ta layer 14 inserted into the soft magnetic layer of the free magnetic layer 6 is a single layer, but may be two or more layers. When the Co—Ta layer 14 is two or more layers, a laminated structure of soft magnetic layer / Co—Ta layer / soft magnetic layer / Co—Ta layer / soft magnetic layer is formed.

  However, if the number of the Co—Ta layers 14 is increased, the entire thickness of the free magnetic layer 6 is increased, and a sufficient increase in resistance change rate (ΔR / R) cannot be expected. The magnetostriction λs of the magnetic layer 6 is also likely to increase, and when the number of the Co—Ta layers 14 is more than one, it is preferably between 2 and 8 layers.

In the present embodiment, in order to obtain an effective high rate of change in resistance (ΔR / R), the second pinned magnetic layer 4c has a single layer structure of Co—Fe—B, or Co—Fe—B and Co—. It is preferable to form a laminated structure with Fe (Co—Fe is on the insulating barrier layer 5 side). Co-Fe-B constituting the second fixed magnetic layer 4c, the composition formula is made of _{(Co β Fe 100-β)} 100-γ B γ, the atomic ratio beta, 5 to 75, the gamma compositional ratio 10 It is preferably formed at ˜30 at%. Thus, the insulating barrier layer 5 and the enhancement layer 12 formed on the second pinned magnetic layer 4c are appropriately {100} planes in a plane direction parallel to the film plane (XY plane). It is possible to form a body-centered cubic structure (bcc structure) in which equivalent crystal planes expressed as are preferentially oriented, and a high resistance change rate (ΔR / R) can be obtained.

  In the present embodiment, the first soft magnetic layer 13 and the second soft magnetic layer 15 are formed of Ni—Fe, and the enhancement layer 12 is formed of Co—Fe, so that a high resistance change rate (ΔR / R). And the soft magnetic properties of the free magnetic layer 6 can be kept good.

  In addition, as in the case of the experimental layer configuration described later, the effect of applying this embodiment to a tunneling magnetic sensing element in which the pinned magnetic layer 4, the insulating barrier layer 5, and the free magnetic layer 6 are stacked in this order from the bottom. Therefore, it is possible to obtain a higher resistance change rate (ΔR / R) than in the prior art.

  A method for manufacturing the tunneling magnetic sensing element of this embodiment will be described. 5 to 8 are partial cross-sectional views of the tunnel-type magnetic sensing element during the manufacturing process, and all show a cross-section at the same position as the tunnel-type magnetoresistive effect element shown in FIG. 6 to 8, the free magnetic layer is illustrated as a single layer structure, but in actuality, the free magnetic layer is formed to have a laminated structure shown in FIG.

  In the process shown in FIG. 5, the underlayer 1, the seed layer 2, the antiferromagnetic layer 3, the first pinned magnetic layer 4a, the nonmagnetic intermediate layer 4b, and the second pinned magnetic layer are formed on the lower shield layer 21 in order from the bottom. The layer 4c and the insulating barrier layer 5 are continuously formed in the same vacuum.

  In this embodiment, the insulating barrier layer 5 is formed of Mg—O (magnesium oxide). The insulating barrier layer 5 is obtained, for example, by sputtering Mg—O on the second pinned magnetic layer 4 c using an Mg—O target formed at a predetermined composition ratio.

  Next, as shown in FIG. 6, a free magnetic layer 6 and a protective layer 7 are continuously formed on the insulating barrier layer 5 in the same vacuum as in FIG.

In the present embodiment, as shown in FIG. 2, the free magnetic layer 6 is laminated from the bottom in the order of the enhancement layer 12, the first soft magnetic layer 13, the Co—Ta layer 14, and the second soft magnetic layer 15. Preferably, the enhancement layer 12 is formed of a Co—Fe alloy, and the first soft magnetic layer 13 and the second soft magnetic layer 15 are formed of a Ni—Fe alloy.
In this way, the laminate 10 in which the layers from the underlayer 1 to the protective layer 7 are laminated is formed.

  Next, a lift-off resist layer 30 is formed on the laminate 10, and both end portions in the track width direction (X direction in the drawing) of the laminate 10 not covered with the lift-off resist layer 30 are etched. (See FIG. 7).

  Next, the insulating layer 22, the hard bias layer 23, and the protective layer 24 are stacked in this order on the lower shield layer 21 on both sides in the track width direction (X direction in the drawing) of the stacked body 10 (see FIG. 8).

  Then, the lift-off resist layer 30 is removed, and an upper shield layer 26 is formed on the stacked body 10 and the protective layer 24.

  In the present embodiment, the Co—Ta layer 14 is interposed between the first soft magnetic layer 13 and the second soft magnetic layer 15, so that the first soft magnetic layer 13 in contact with the enhancement layer 12 is thin. Can be formed. When the first soft magnetic layer 13 is formed of Ni—Fe, the first soft magnetic layer 13 is typically represented as a {111} plane in a plane direction parallel to the interface (XY plane). An equivalent crystal plane is formed with a face-centered cubic structure (fcc structure) in which preferential orientation is performed.

  In the tunnel-type magnetic sensing element in which the insulating barrier layer 5 is formed of Mg—O, the second pinned magnetic layer 4c / insulating barrier layer 5 / enhancement layer 12 are in a plane direction parallel to the interface (XY plane). It is important to improve the rate of change in resistance (ΔR / R) that an equivalent crystal plane typically represented as a {100} plane is formed with a body-centered cubic structure (bcc structure) preferentially oriented. However, since the first soft magnetic layer 13 in contact with the enhancement layer 12 can be formed thin as described above, the crystal orientation of the first soft magnetic layer 13 itself can be weakened. Moreover, since the Co—Ta layer 14 is an amorphous magnetic layer, the crystal orientation between the first soft magnetic layer 13 and the second soft magnetic layer 15 can be divided. As a result, the enhancement layer 12 is effectively formed as a {100} plane on the insulating barrier layer 5 made of Mg—O in a plane direction parallel to the interface (XY plane). It can be formed with a body-centered cubic structure (bcc structure) in which equivalent crystal planes represented are preferentially oriented.

  Further, when Co—Ta having a negative magnetostriction λs in bulk is inserted as a Co—Ta layer 14 into the soft magnetic layer of the free magnetic layer 6, the conventional Co—Ta layer 14 is not inserted as shown in the experimental results described later. The magnetostriction λs of the free magnetic layer 6 is slightly larger than that of the example, but the increase in the magnetostriction λs of the free magnetic layer 6 is suppressed in this embodiment as compared with the comparative example in which the Ta layer is inserted in the soft magnetic layer. it can.

  As described above, in this embodiment, it is possible to easily and appropriately manufacture a tunnel type magnetic sensing element capable of increasing the rate of change in resistance (ΔR / R) as compared with the conventional one while suppressing an increase in magnetostriction λs of the free magnetic layer 6.

  In the above-described method for manufacturing a tunneling magnetic sensing element, a heat treatment is included after the stacked body 10 is formed. A typical heat treatment is a heat treatment for generating an exchange coupling magnetic field (Hex) between the antiferromagnetic layer 3 and the first pinned magnetic layer 4a.

  The structure in which the free magnetic layer 6, the insulating barrier layer 5, and the pinned magnetic layer 4 are stacked in this order from the bottom described with reference to FIG. 3, and the dual structure described with reference to FIG. Manufactured according to

  The tunnel-type magnetic detection element of this embodiment can be used as an MRAM (magnetoresistance memory) or a magnetic sensor in addition to the use as a magnetic head built in a hard disk device.

  As shown in FIG. 2, a tunnel-type magnetic including the following laminated body having a free magnetic layer laminated in the order of an enhancement layer 12 / first soft magnetic layer 13 / Co—Ta layer 14 / second soft magnetic layer 15 from the bottom. A detection element was formed.

From the bottom, the laminated body is formed from underlayer 1; Ta (30) / seed layer 2; Ru (40) / antiferromagnetic layer 3; Ir _{20 at%} Mn _{80 at%} (80) / pinned magnetic layer 4 [first pinned magnetic layer Layer 4a; Fe _{30 at%} Co _{70 at%} (22) / nonmagnetic intermediate layer 4 b; Ru (9.1) / second pinned magnetic layer 4 c; [{Co ₅₀ Fe ₅₀ } _{70 at%} B _{30 at%} (18) / Co _{50 at%} Fe _{50 at%} (8)]] / insulating barrier layer 5; Mg _{50 at%} O _{50 at%} (11.2) / free magnetic layer 6 [enhanced layer 12; Fe _{50 at%} Co _{50 at%} (10) / first soft Magnetic layer 13; Ni _{87 at%} Fe _{13 at%} (15) / Co-Ta layer 14; Co _{75 at%} Ta _{25 at%} / second soft magnetic layer 15; Ni _{87 at%} Fe _{13 at%} (35)] / protective layer 7; Ru (20 / Were stacked in the order of Ta (180)].
The numerical value in the parenthesis of each layer in the above laminate shows the average film thickness and the unit is Å.

In the experiment, a plurality of samples (examples) in which the Co—Ta layer 14 composed of Co _{75 at%} Ta _{25 at%} was formed with different average film thicknesses in the range of 2 to 20 mm.
After forming the laminate, heat treatment was performed at 270 ° C. for 3 hours and 40 minutes.

[Conventional example]
Of the laminate of the above example, a sample in which the Co—Ta layer 14 is not formed and a soft magnetic layer having a single layer structure of Ni _{87 at%} Fe _{13 at% with} an average thickness of 50 _mm is formed on the enhancement layer. The sample was prepared and used as a conventional example.
After forming the laminate of the conventional example, the same heat treatment as in the example was performed.

[Comparative example]
In the laminated body of the above-described example, a sample in which a Ta layer having an average film thickness of 2 mm, 4 mm, or 6 mm is inserted between the first soft magnetic layer and the second soft magnetic layer instead of the Co-Ta layer 14 is manufactured. These samples were used as comparative examples. After forming the laminate of the comparative example, the same heat treatment as in the example was performed.

In the experiment, the magnetostriction λs, the resistance change rate (ΔR / R), and the like of the free magnetic layers of the examples, the conventional examples, and the comparative examples were measured.
The experimental results are shown in Table 1 below.

  FIG. 9 is a graph showing the experimental results showing the magnetostriction λs of the free magnetic layer of each example, conventional example, and each comparative example.

  As shown in FIG. 9, it was found that the magnetostriction λs of the free magnetic layer gradually increased as the thickness of the Co—Ta layer of the example was increased. In order to stabilize the reproduction characteristics, it is desirable that the magnetostriction λs of the free magnetic layer is as close to 0 as possible.

  In the example, although the magnetostriction λs of the free magnetic layer is larger than that of the conventional example, the increase of the magnetostriction λs of the free magnetic layer can be suppressed smaller than that of the comparative example in which the Ta layer is inserted in the soft magnetic layer. I understood.

  FIG. 10 is a graph showing experimental results showing the rate of change in resistance (R / R) of each example, conventional example, and each comparative example.

  As shown in FIG. 10, it was found that the example can increase the rate of change in resistance (ΔR / R) more than the conventional example. It was also found that the rate of resistance change (R / R) gradually increased as the thickness of the Co—Ta layer of the example was increased.

  Further, it was found that even in the comparative example in which the Ta layer was inserted into the soft magnetic layer, the resistance change rate (ΔR / R) could be increased by increasing the thickness of the Ta layer.

  FIG. 11 is a graph showing the relationship between the magnetostriction λs of the free magnetic layer and the rate of change in resistance (ΔR / R) in Examples, Conventional Examples, and Comparative Examples based on the experimental results shown in Table 1, FIG. 9 and FIG. .

  The following can be derived from the results of this experiment. That is, in the example and the comparative example, when the film thickness of the Co—Ta layer in the example and the film thickness of the Ta layer in the comparative example are selected so that the magnetostriction λs of the free magnetic layer is equal, the example is better. The film thickness of the Co—Ta layer in the examples can be made larger than that of the comparative example, or the resistance change rate (R / R) can be equal in the examples and comparative examples. And when the film thickness of the Ta layer in the comparative example was selected, it was found that the magnetostriction λs of the free magnetic layer can be made smaller in the example than in the comparative example.

  Based on the experimental results shown in FIGS. 9 to 11, in this example, the average film thickness of the Co—Ta layer was set to 2 to 20 mm.

  Further, as shown in FIG. 10, even when the thickness of the Co—Ta layer is made larger than 14 mm, the rate of change in resistance (ΔR / R) remains unchanged, and as shown in FIG. 9, the thickness of the Co—Ta layer is Since the magnetostriction λs of the free magnetic layer further increases when the thickness is larger than 14 mm, the upper limit value of the average film thickness of the Co—Ta layer is set to 14 mm.

  As shown in FIG. 10, when the average thickness of the Ta layer is about 4 mm, the resistance change rate (ΔR / R) can be maximized in the comparative example.

  On the other hand, in this example, when the average film thickness of the Co—Ta layer is set to 10 mm or more and 14 mm or less, the resistance change rate (ΔR / R) larger than the maximum resistance change rate (ΔR / R) in the comparative example. It was found that the magnetostriction λs of the free magnetic layer can be made smaller than that of the comparative example.

  Further, as shown in Table 1 and FIG. 9, when the average film thickness of the Co—Ta layer is in the range of 2 mm or more and 8 mm or less, compared with the comparative example in which the Ta layer is inserted in the soft magnetic layer. The magnetostriction λs of the free magnetic layer can be effectively reduced.

  At this time, as shown in FIG. 10, the rate of change in resistance (ΔR / R) tends to be smaller in the example than in the comparative example, but the average film thickness of the Co-Ta layer is 2 mm or more and 8 mm or less. If it is within the range, the resistance change rate (ΔR / R) can be increased as compared with the prior art while keeping the increase in magnetostriction λs of the free magnetic layer very small when viewed from the conventional example. It becomes possible.

  In the example shown in Table 1, RA (element resistance R × element area A), coercive force Hc of the free magnetic layer, and interlayer coupling magnetic field Hin acting between the free magnetic layer and the fixed magnetic layer are substantially equal to those of the conventional example. I understood that I can do it.

Sectional drawing which cut | disconnected the tunnel type | mold magnetic detection element in the surface direction parallel to the opposing surface with a recording medium, The partial expanded sectional view cut | disconnected from the same surface direction as FIG. 1 which shows the structure of the tunnel type magnetic sensing element of 1st Embodiment, The partial expanded sectional view cut | disconnected from the same surface direction as FIG. 1 which shows the structure of the tunnel type magnetic sensing element of 2nd Embodiment, The partial expanded sectional view cut | disconnected from the same surface direction as FIG. 1 which shows the structure of the tunnel type magnetic sensing element of 3rd Embodiment, FIG. 1 is a cross-sectional view of a tunnel-type magnetic sensing element during a manufacturing process cut from the same direction as FIG. One process diagram (cross-sectional view) performed after FIG. One process diagram (cross-sectional view) performed after FIG. One process diagram (cross-sectional view) performed next to FIG. Example in which a Co—Ta layer was inserted into a soft magnetic layer (Ni—Fe) of a free magnetic layer (experiment with a plurality of samples having different thicknesses of the Co—Ta layer), and a soft magnetic layer of a free magnetic layer A conventional example in which the Co—Ta layer is not inserted in (Ni—Fe) and a comparative example in which a Ta layer is inserted in the soft magnetic layer (Ni—Fe) of the free magnetic layer (a plurality of different Ta layer thicknesses) A graph showing the magnetostriction λs of the free magnetic layer of the experiment) Graph showing resistance change rate (ΔR / R) of Examples, Conventional Examples and Comparative Examples, The graph which shows the relationship of magnetostriction (lambda) and resistance change rate ((DELTA) R / R) of the free magnetic layer of an Example, a prior art example, and a comparative example,

Explanation of symbols

3 Antiferromagnetic layer 4 Pinned magnetic layer 4a First pinned magnetic layer 4b Nonmagnetic intermediate layer 4c Second pinned magnetic layer 5 Insulating barrier layer 6 Free magnetic layers 7 and 24 Protective layer 10 Stack 12 and 27 Enhance layer 13 First Soft magnetic layer 14 Co-Ta layer 15 Second soft magnetic layer 17 Lower insulating barrier layer 18 Upper insulating barrier layer 22 Insulating layer 23 Hard bias layers 25 and 28 Soft magnetic layer 30 Resist layer

Claims (8)

A pinned magnetic layer whose magnetization direction is fixed from below, an insulating barrier layer, and a free magnetic layer whose magnetization direction varies with respect to an external magnetic field, or from below, the free magnetic layer, the insulating barrier layer, and Having a laminate comprising laminated portions laminated in the order of the pinned magnetic layers;
The insulating barrier layer is formed of Mg-O;
The free magnetic layer includes a soft magnetic layer and an enhancement layer positioned between the soft magnetic layer and the insulating barrier layer and having a higher spin polarizability than the soft magnetic layer,
In the soft magnetic layer, a Co—Ta layer is inserted in a plane direction parallel to the interface of each layer constituting the laminate, and the soft magnetic layer has a film thickness through the Co—Ta layer. A tunnel-type magnetic detection element characterized by being divided into a plurality of layers in a direction.   2. The tunneling magnetic sensing element according to claim 1, wherein a Ta composition ratio X of the Co—Ta layer is 10 at% or more and 40 at% or less.   3. The tunneling magnetic sensing element according to claim 1, wherein an average film thickness of the Co—Ta layer is in a range of 2 to 20 mm.   4. The tunneling magnetic sensing element according to claim 3, wherein an average film thickness of the Co—Ta layer is in a range of 2 to 14 mm.   4. The tunneling magnetic sensing element according to claim 3, wherein an average film thickness of the Co—Ta layer is in a range of 10 to 14 mm.   4. The tunneling magnetic sensing element according to claim 3, wherein an average film thickness of the Co—Ta layer is in a range of 2 to 8 mm.   The tunnel magnetic sensing element according to claim 1, wherein the soft magnetic layer is made of Ni—Fe, and the enhancement layer is made of Co—Fe.   The tunneling magnetic sensing element according to any one of claims 1 to 7, wherein the pinned magnetic layer, the insulating barrier layer, and the free magnetic layer are laminated in this order from the bottom.

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