Magnetoresistive element, magnetoresistive magnetic head, magnetic recording device, magnetoresistive memory device, and magnetic sensor

Abstract

This magnetoresistive element comprises a multilayer film including two magnetic layers and a non-magnetic insulating layer disposed between the two magnetic layers, wherein: one among the two magnetic layers is a free magnetic layer and the other is a fixed magnetic layer; and at least one among the two magnetic layers contains a ferromagnetic material M-X represented by the formula M100-aXa, where M is at least one element selected from among Fe, Co, and Ni, X is represented by the formula X1 bX2 c, X1 is at least one element selected from among Ru, Rh, Pd, Ir, and Pt, X2 is at least one element selected from among Cr and Mn, and a, b, and c satisfy 5≤a≤60, 0≤b≤60, 0≤c≤30, and a=b+c.

Description

Magnetoresistive element, magnetoresistive magnetic head, magnetic recording device, magnetoresistive memory device and magnetic sensor

[0001] The present invention relates to a magnetoresistive element (hereinafter sometimes abbreviated as "MR element") and a magnetic device using the same. In particular, the MR element according to the present invention relates to a magnetoresistive magnetic head such as a magnetic recording / reproducing head that reads information from a medium such as a magnetic disk, a magneto-optical disk, or a magnetic tape, a magnetic recording device equipped with a magnetoresistive magnetic head, a magnetic sensor used in automobiles, robots, etc., and a magnetoresistive memory device such as a magnetic random access memory (hereinafter sometimes abbreviated as "MRAM").

[0002] Known magnetoresistive elements include multilayer structures in which at least two magnetic layers and at least one nonmagnetic insulating layer made of an insulating material are alternately stacked. Multilayer structures with such structures can produce a large magnetoresistance called the tunneling magnetoresistance (TMR) effect. The nonmagnetic insulating layers in multilayer structures are arranged between magnetic layers (e.g., magnetic layer / nonmagnetic insulating layer / magnetic layer / nonmagnetic insulating layer...). Magnetoresistance is a phenomenon in which electrical resistance changes depending on the relative difference in the magnetization direction between the magnetic layers.

[0003] As the insulating material for the non-magnetic insulating layer, magnesium oxide (MgO) is used (Non-Patent Document 1), magnesium fluoride (MgF ２ ) is known (Patent Document 1).

[0004] In addition, Non-Patent Document 2 describes an MgF FET with low leakage and in which the occurrence of pinholes is suppressed by the placement of a seed layer made of MgO. ２It is disclosed that an insulating layer is formed. However, the magnetoresistance change rate of the magnetoresistance element disclosed in Non-Patent Document 2 is less than 1% at room temperature and 10% at 4.2 K, resulting in extremely poor performance. When MgO is used as the material for the nonmagnetic insulating layer in a magnetoresistance element, the crystalline state of the magnetic layer and the nonmagnetic insulating MgO layer significantly affects the magnetoresistance change characteristics of the magnetoresistance element. To achieve high magnetoresistance change characteristics, it is important that both the magnetic layer and the nonmagnetic insulating MgO layer have good crystalline states. Both the magnetic layer and the nonmagnetic insulating layer in a magnetoresistance element are thin films. The thin films are formed, for example, by sputtering. However, it is difficult to stack metal thin films and oxide thin films in a good crystalline state, and crystalline defects are particularly likely to occur in the MgO layer. One known example of forming a metal thin film is to first form an amorphous thin film and then crystallize it to achieve a good crystalline state. However, crystalline defects are likely to occur in MgO layers not only when a crystalline film is directly formed, but also when an amorphous film is formed and then crystallized. It is important to suppress the occurrence of such crystal defects as much as possible in order to obtain high magnetoresistance characteristics.

[0005] Furthermore, Patent Document 2 discloses that by using MgO doped with fluorine as the material for the non-magnetic insulating layer and determining the amount of fluorine added, it is possible to realize a magnetoresistive element that exhibits high magnetoresistance change characteristics, and to suppress the occurrence of crystal defects in the non-magnetic insulating layer.

[0006] On the other hand, Non-Patent Document 3 discloses the effect of fluoride on the crystal growth of MgO. More specifically, when fluoride is added during sintering of bulk MgO ceramic from MgO powder, the crystal growth of MgF ２ The addition of MgF increases the grain size of MgO, but at temperatures below 900°C, ２It has been shown that the addition of MgO actually suppresses the crystal growth of MgO. However, there is no description of a magnetoresistive element having a suitable combination of a magnetic layer and a non-magnetic insulating layer that exhibits high magnetoresistive characteristics after heat treatment at 350°C to 450°C, and the magnetoresistive characteristics of such a magnetoresistive element are not well understood.

[0007] Furthermore, Patent Document 3 discloses the use of Al—O, Al—N, or Al—N—O as the material for the nonmagnetic insulating layer. Patent Document 3 also discloses knowledge about magnetic metals suitable for magnetic layers with excellent heat resistance. However, Patent Document 3 does not disclose any knowledge about the use of MgO or fluorine-added MgO as the material for the nonmagnetic insulating layer, as described above.

[0008] Japanese Patent Publication No. 2001-156357 Japanese Patent Publication No. 4945704 Japanese Patent Publication No. 2004-524708

[0009] "230% room-temperature magnetoresistance in CoFeB / MgO / CoFeB magnetic tunnel junctions", David D. Djayaprawira et al., APPLIED PHYSICS LETTERS 86, 092502 (2005). Received 25 October 2004; accepted 24 January 2005; published online 23 February 2005. S. Mitani et al., "Structure and tunnel magnetoresistance in Fe / MgF2 / Co junctions with an oxide seed layer on an Fe bottom electrode", Journal of Applied Physics, vol. 91 (2002), pp. 7200-7202. M. Mabo et al., "Effect of Fluoride Addition on Crystal Growth of MgO", Journal of the Ceramic Society of Japan, vol. 97 (1989), pp. 857-863.

[0010] In the future, magnetic devices using MR elements, such as magnetic heads, MRAM devices, and magnetic sensors, will be required to have even larger magnetoresistance change rates (MR ratios). In order for MR elements to achieve a large MR ratio in magnetic devices, it is also necessary to suppress degradation of their characteristics due to heat treatment. For example, research is progressing on fabricating MR elements on complementary metal-oxide-semiconductor (CMOS) devices to use as MRAM devices. The fabrication of semiconductor memories such as MRAM necessitates high-temperature heat treatment at approximately 350°C to 450°C in the semiconductor CMOS process. Furthermore, semiconductor mounting boards equipped with magnetic sensors are used in automobiles, etc., and high-temperature reflow heat treatment is also required when fabricating semiconductor mounting boards equipped with magnetic sensors.

[0011] The reason for the deterioration of the MR element due to heat treatment is not entirely clear at present, but it is possible that this is due to disturbance of the interface between the magnetic layer and the non-magnetic insulating layer caused by atomic diffusion or the like.

[0012] MR elements having a large MR ratio, especially those that maintain a high MR ratio even after heat treatment, are extremely important for practical use, and there is a demand for such MR elements, but conventional MR elements cannot adequately meet this demand.

[0013] For example, in the MR element having an MgO layer disclosed in Patent Document 1, crystal defects are likely to occur not only when a crystallized film of the MgO layer is directly formed, but also when an amorphous film is formed and then crystallized to form the MgO layer, which can easily cause deterioration in the characteristics of the MR element.

[0014] Furthermore, the MR element having an MgO layer doped with fluorine disclosed in Patent Document 2 can suppress the occurrence of crystal defects in the MgO layer, but Non-Patent Document 3 does not disclose or suggest the finding that heat treatment at 350°C to 450°C increases the crystallinity of the MgO layer and suppresses defects, and it is not well understood what MR elements have in combination with a suitable magnetic layer and a non-magnetic insulating layer that exhibit high magnetoresistance change characteristics even after heat treatment.

[0015] Furthermore, Patent Document 3 discloses an MR element having a nonmagnetic insulating layer made of Al—O, Al—N, or Al—N—O, but does not describe or suggest findings regarding the use of MgO or fluorine-added MgO as the material for the nonmagnetic insulating layer.

[0016] One aspect of the magnetoresistive element according to the present invention is a magnetoresistive element that operates after undergoing a heat treatment at least equal to or higher than 350° C., and includes a multilayer film including two magnetic layers and a non-magnetic insulating layer disposed between the two magnetic layers, wherein the magnetoresistive element has a resistance value that changes depending on a relative angle between magnetization directions in the two magnetic layers, one of the two magnetic layers is a free magnetic layer and the other of the two magnetic layers is a fixed magnetic layer, and the magnetization of the free magnetic layer is relatively more likely to rotate by an external magnetic field than the magnetization of the fixed magnetic layer, and the magnetoresistive element further includes an antiferromagnetic layer that suppresses the magnetization rotation of the fixed magnetic layer, and at least one of the two magnetic layers has a magnetization represented by the formula M １００－ａ X ａ The present invention includes a ferromagnetic material M-X represented by the formula: １ ｂ X ２ ｃ and X １ is at least one element selected from Ru, Rh, Pd, Ir, and Pt, and X ２ is at least one element selected from Cr and Mn, and a, b, and c are numerical values ​​that satisfy the following formulas: 5≦a≦60, 0≦b≦60, 0≦c≦30, a=b+c; and the nonmagnetic insulating layer is made of an insulating material whose main component is magnesium oxide.

[0017] When magnesium oxide or magnesium oxide doped with fluorine is used as the main component material of the non-magnetic insulating layer laminated on the magnetic layer, a magnetoresistive element (MR element) or the like can be realized that has excellent heat resistance even after heat treatment at 350°C or higher.

[0018] FIG. 1 is a cross-sectional view showing a first example of a magnetoresistive element according to an embodiment. FIG. 2 is a cross-sectional view showing a second example of a magnetoresistive element according to an embodiment. FIG. 3 is a cross-sectional view showing a third example of a magnetoresistive element according to an embodiment. FIG. 4 is a cross-sectional view showing a fourth example of a magnetoresistive element according to an embodiment. FIG. 5 is a cross-sectional view showing a fifth example of a magnetoresistive element according to an embodiment. FIG. 6 is a cross-sectional view showing a sixth example of a magnetoresistive element according to an embodiment. FIG. 7 is a cross-sectional view showing a first example of a magnetic device according to an embodiment. FIG. 8 is a cross-sectional view showing a second example of a magnetic device according to an embodiment. FIG. 9 is a cross-sectional view showing a third example of a magnetic device according to an embodiment. FIG. 10 is a diagram showing an example of a magnetic recording apparatus according to an embodiment. FIG. 11 is a cross-sectional view showing a fourth example of a magnetic device according to an embodiment. FIG. 12A is a cross-sectional view showing a fifth example of a magnetic device according to an embodiment. FIG. 12B is a diagram showing an example of a bridge circuit used in the fifth example of a magnetic device according to an embodiment. FIG. 13A is a diagram showing the relationship between heat treatment temperature and MR ratio measured based on Table 2 in Example 1. FIG. 13B is a diagram showing the relationship between heat treatment temperature and MR ratio measured based on Table 2 in Example 1. FIG. 13C is a graph showing the relationship between the heat treatment temperature and the MR ratio measured based on Table 2 in Example 1. FIG. 13D is a graph showing the relationship between the heat treatment temperature and the MR ratio measured based on Table 2 in Example 1. FIG. 14A is a graph showing the relationship between the heat treatment temperature and the MR ratio measured based on Table 3 in Example 1. FIG. 14B is a graph showing the relationship between the heat treatment temperature and the MR ratio measured based on Table 3 in Example 1. FIG. 14C is a graph showing the relationship between the heat treatment temperature and the MR ratio measured based on Table 3 in Example 1. FIG. 14D is a graph showing the relationship between the heat treatment temperature and the MR ratio measured based on Table 3 in Example 1. FIG. 14E is a graph showing the relationship between the heat treatment temperature and the MR ratio measured based on Table 3 in Example 1. FIG. 15 is a graph showing the relationship between the heat treatment temperature and the MR ratio measured based on Table 4 in Example 2. FIG. 16 is a graph showing the relationship between the heat treatment temperature and the MR ratio measured based on Table 5 in Example 3.

[0019] Preferred embodiments of the present invention will now be described.

[0020] The magnetoresistive element (MR element) according to this embodiment includes a multilayer film including two magnetic layers and a nonmagnetic insulating layer disposed between the two magnetic layers. The MR element according to this embodiment has a resistance value that changes depending on the relative angle between the magnetization directions of the two magnetic layers, and the two magnetic layers are free magnetic layers or fixed magnetic layers. That is, one of the two magnetic layers is a free magnetic layer, and the other of the two magnetic layers is a fixed magnetic layer. The magnetization of the free magnetic layer is more likely to rotate due to an external magnetic field than the magnetization of the fixed magnetic layer. The MR element according to this embodiment further includes an antiferromagnetic layer that suppresses the magnetization rotation of the fixed magnetic layer, which is one of the magnetic layers.

[0021] In the MR element according to this embodiment, the main component of the insulating material constituting the non-magnetic insulating layer is magnesium oxide (MgO) or magnesium oxide (MgO) doped with fluorine (F). This embodiment provides a combination of magnetic materials suitable for use in the magnetic layer of a magnetoresistive element (MR element) that has excellent heat resistance when subjected to heat treatment at 350° C. or higher.

[0022] At least one of the two magnetic layers has the formula M １００－ａ X ａ In this embodiment, the ferromagnetic material M-X is represented by the formula M １００－ａ X ａ X in the formula X １ ｂ X ２ ｃ Therefore, the formula M １００－ａ X ａ is the formula M １００－ａ (X １ ｂ X ２ ｃ ) (a=b+c). The magnetic element M in the ferromagnetic material M-X is at least one element selected from Fe, Co, and Ni. The non-magnetic element X in the ferromagnetic material M-X is X １ , X ２ They are classified into two types and are to be used within appropriate ranges set according to their type.

[0023] Non-magnetic element １is a platinum group element (Ru, Rh, Pd, Ir, Pt) whose number of outer shell electrons (d electrons) is equal to or greater than that of Fe. In particular, platinum group elements have the property of exhibiting significant magnetism when added to the magnetic element M, resulting in a higher spin polarization than when other elements are used. This is advantageous for obtaining a high MR ratio. Furthermore, platinum group elements have large atomic diameters and are chemically stable, so they are also useful for achieving device process stability, i.e., high heat resistance, when obtaining a junction structure in an MR element.

[0024] Non-magnetic element ２ is an element selected from Cr and Mn. Addition of these elements to the magnetic element M also increases the spin polarization and improves the MR ratio.

[0025] Ferromagnetic material M-X to X １ ｂ , X ２ ｃ When at least one of the above is contained (b+c>0), an MR element having a high MR ratio can be obtained. １ ｂ , X ２ ｃ By including both (b>0, c>0), it is possible to obtain an MR element with a high MR ratio, excellent heat resistance, and controlled magnetic anisotropy.

[0026] The MR element according to this embodiment may be a spin-valve element. A spin-valve element includes a free magnetic layer and a pinned magnetic layer as magnetic layers, and the magnetization of the free magnetic layer is more likely to rotate relative to the magnetization of the pinned magnetic layer due to an external magnetic field. In this case, the ferromagnetic material may be included in at least one of the pinned magnetic layer and the free magnetic layer. When the free magnetic layer includes the ferromagnetic material M-X, it is easy to improve soft magnetic properties, such as reducing the shift field in the free magnetic layer, and to suppress deterioration of the soft magnetic properties due to heat treatment. When the pinned magnetic layer includes the ferromagnetic material M-X, the heat resistance of the MR characteristics is improved. In particular, in a spin-valve film including a Mn-based antiferromagnetic material, deterioration of the MR ratio caused by impurity diffusion is suppressed. In a preferred embodiment of this embodiment, a pinned magnetic layer including the ferromagnetic material M-X is disposed between an antiferromagnetic layer including Mn and a nonmagnetic insulating layer. In such an MR element, the adverse effects of Mn diffusion from the antiferromagnetic layer can be suppressed.

[0027] As described above, the MR element according to this embodiment further includes an antiferromagnetic layer that suppresses the magnetization rotation of the pinned magnetic layer. In this case, various antiferromagnetic materials can be used for the antiferromagnetic layer.

[0028] The magnetic layer containing the ferromagnetic material M-X may be a single-layer film or a multi-layer film. When the magnetic layer is a multi-layer film containing magnetic films, it is preferable that at least one of the magnetic films is a film made of the ferromagnetic material M-X. In particular, by making the magnetic film in contact with the non-magnetic insulating layer a magnetic film made of the ferromagnetic material M-X, heat resistance is greatly improved.

[0029] The magnetic layer may be a multilayer film including a nonmagnetic insulating layer and a pair of magnetic films sandwiching the nonmagnetic insulating layer. In particular, the magnetic layer may be a multilayer film including a nonmagnetic insulating layer and a pair of magnetic films antiferromagnetically or magnetostatically coupled via the nonmagnetic insulating layer. The magnetic layer may be a layer in which a nonmagnetic element X is added only to a portion of a layer made of a magnetic element M, for example, a multilayer film represented as M / M-X. The free magnetic layer may also be a multilayer film including a magnetic film made of M-X and a soft magnetic film having superior soft magnetic properties to the magnetic film made of M-X, stacked together with the soft magnetic film. This allows the magnetization of the free magnetic layer to rotate more easily. The magnetic layer may also include a nonmagnetic insulating layer or an interfacial magnetic film formed at the interface with the nonmagnetic insulating layer. The interfacial magnetic film is expected to increase the MR ratio. Examples of the interfacial magnetic film include Fe ３ O ４ , CrO ２ Examples of such films include those having a thickness in the range of about 0.5 to 2 nm.

[0030] When a current is passed perpendicular to the film surface, the MR element may further include a pair of electrode layers disposed so as to sandwich the multilayer film of magnetic layer / non-magnetic insulating layer.

[0031] The magnetic element M is represented by the formula Fe １－ｐ－ｑ Co ｐ Ni ｑ Therefore, an element represented by the formula M １００－ａ X ａ The ferromagnetic material M-X represented by the composition formula [Fe １－ｐ－ｑ Co ｐ Ni ｑ ] １００－ａ [X １ ｂ X ２ ｃ X ３ ｄ ] ａ Here, p and q are adjusted in the ranges of 0≦p≦1, 0≦q≦1, and p+q≦1.

[0032] In this case, when the magnetic element M in the ferromagnetic material M-X is a ternary system (0<p<1, 0<q<1, p+q<1), p and q are preferably in the ranges of 0<p<1, 0<q≦0.9 (for example, 0<q≦0.65), respectively. Also, when the magnetic element M is a binary system of Fe and Ni (p=0, 0<q<1; Fe １－ｑ Ni ｑ ), q is preferably in the range of 0<q≦0.95. When the magnetic element M is a binary system of Fe and Co (q=0, 0<p<1; Fe １－ｐ Co ｐ ), p is preferably in the range of 0<p≦0.95.

[0033] When the magnetic film containing the ferromagnetic material M-X is a Co-Fe-B layer, the formula M １００－ａ X １ ｂ X ２ ｃ In the ferromagnetic material M-X represented by the formula {Co （１－ｘ） Fe ｘ} ０．８ B ０．２ It is preferable to configure the alloy so as to have a Co—Fe—B alloy represented by the formula: where x is a value that satisfies the formula 0.25≦x≦0.5, and the formula M １００－ａ X １ ｂ X ２ ｃ In the formula, a, b, and c preferably satisfy the following conditions: 5≦a≦20, 0≦b≦20, 0≦c≦10, and a=b+c.

[0034] Since Pt is an element that can achieve both a high MR ratio and excellent heat resistance, it is preferable to use Pt as the non-magnetic element X in the ferromagnetic material M-X. When Pt is used as the non-magnetic element X, it is preferable to set a in the range of 5 to 50 (5≦a≦50) and c=0. In this case, when the magnetic element M is represented by the formula Fe １－ｑ Ni ｑ When the magnetic element M is represented by the formula Fe, q is set within the range of 0<q≦0.9. １－ｐ Co ｐ When the magnetic element M is expressed by the formula (1), it is preferable to limit p to the range of 0<p≦0.9. The magnetic element M used together with Pt may be Fe.１００－ａ Pt ａ When using a magnetic material having a large reversal magnetic field, a high MR ratio, and excellent heat resistance, it is preferable that a is in the range of 0.05≦a<20.

[0035] Other preferred examples of the non-magnetic element X are Pd, Rh, and Ir. When using these elements, it is also preferable that a is in the range of 5 to 50 and c=0.

[0036] The non-magnetic element X may be at least two elements selected from Cr, Mn, Ru, Rh, Pd, Ir, and Pt.

[0037] The ferromagnetic material M-X may have a composition gradient in the thickness direction. The details of the composition gradient are not particularly limited. The ratio of the magnetic element M to the non-magnetic element X may increase or decrease monotonically in the thickness direction, or may vary periodically.

[0038] Next, specific embodiments of the present invention will be described with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present invention. Therefore, the numerical values, shapes, materials, components, component placement positions, connection forms, etc. shown in the following embodiments are merely examples and are not intended to limit the present invention. Therefore, among the components in the following embodiments, components that are not recited in the independent claims will be described as optional components.

[0039] Note that each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, the scales and the like do not necessarily match in each figure. Furthermore, in each figure, the same reference numerals are used for substantially the same configurations, and redundant explanations will be omitted or simplified.

[0040] First, the MR element according to this embodiment and a magnetic device (magnetoresistive head, MRAM, etc.) using this MR element will be described.

[0041] FIG. 1 is a cross-sectional view showing an example of an MR element according to an embodiment.

[0042] 1, the MR element 100 includes two magnetic layers, a first magnetic layer 1 and a second magnetic layer 3, stacked with a non-magnetic insulating layer 2 interposed therebetween. That is, the first magnetic layer 1, the non-magnetic insulating layer 2, and the second magnetic layer 3 are stacked in this order.

[0043] The first magnetic layer 1 and the second magnetic layer 3 have different magnetization reversal fields (coercive forces). Specifically, the coercive force of the first magnetic layer 1 is greater than the coercive force of the second magnetic layer 3. In this embodiment, the first magnetic layer 1, which has a relatively large coercive force, is the pinned magnetic layer, and the second magnetic layer 3, which has a relatively small coercive force, is the free magnetic layer.

[0044] The nonmagnetic insulating layer 2 is made of a material whose main component is magnesium oxide, or a material whose main component is magnesium oxide that partially contains fluorine. When the main component material of the nonmagnetic insulating layer 2 is magnesium oxide that partially contains fluorine, the amount of fluorine added is preferably 0.005 atm% or more and 0.15 atm% or less, and further, for example, 0.005 atm% or more and 0.05 atm% or less.

[0045] The first magnetic layer 1, which is the pinned magnetic layer, may be a single layer or a multilayer film. When the first magnetic layer 1 is a multilayer film, the first magnetic layer 1 may be, for example, a multilayer film made up of a ferromagnetic material M-X layer / Co-Fe-B layer, or a multilayer film made up of a magnetic layer with a relatively large coercive force / ferromagnetic material M-X layer / Co-Fe-B layer.

[0046] The second magnetic layer 3, which is the free magnetic layer, may also be a single layer or a multilayer film. An example of a single layer second magnetic layer 3 is a ferromagnetic material Co—Fe—B layer. When the second magnetic layer 3 is a multilayer film, the second magnetic layer 3 may be a multilayer film composed of a Co—Fe—B layer / magnetic layer with a relatively small coercive force, a multilayer film composed of a ferromagnetic material Co—Fe—B layer / M-X layer, or a multilayer film composed of a Co—Fe—B layer / ferromagnetic material M-X layer / magnetic layer with a relatively small coercive force.

[0047] The magnetic layer having a relatively large coercive force is made of, for example, Co—Pt, Co—Cr—Pt, Co—Ta—Pt, Co—Sm, Fe—Tb, etc. The coercive force of the magnetic layer having a relatively large coercive force is preferably 100 Oe or more (approximately 7.96 kA / m or more).

[0048] The magnetic layer having a relatively small coercive force is made of, for example, a Ni--Co--Fe alloy. ｓ Co ｔ Fe ｕ When s is 0.6≦s≦0.9, 0≦t≦0.4, 0≦u≦0.3, a Ni-rich soft magnetic film is suitable, or when s is 0.4, 0.2≦t≦0.95, 0≦u≦0.5, a Co-rich soft magnetic film is suitable.

[0049] By using the ferromagnetic material M--X, it is possible to obtain a larger MR ratio and improved heat resistance than conventional MR elements that use magnetic layers made only of Fe, Co, Ni or alloys thereof.

[0050] More specifically, the reason for the high MR achieved by the ferromagnetic material M-X is believed to be due to the following multiple effects. The first effect is that the density of states of the Fermi surface of the magnetic element M is changed by the nonmagnetic element X, thereby increasing the spin polarization near the Fermi surface. The second effect is that the nonmagnetic element X causes changes in the interatomic distance and electron configuration of the magnetic atoms that make up the magnetic element M, thereby changing the band structure and increasing the spin polarization. The third effect is that the above material improves the junction at the interface between the nonmagnetic layer and the magnetic layer at the atomic level, thereby reducing scattering that does not contribute to magnetoresistance.

[0051] As mentioned above, the reason for the improvement in heat resistance due to the ferromagnetic material M-X is not entirely clear at present, but it is speculated that the addition of the nonmagnetic element X not only alleviates the effects of atomic diffusion at the interface between the magnetic layer and the nonmagnetic insulating layer, but also stabilizes the interface through an appropriate combination of the magnetic layer and the nonmagnetic insulating layer, resulting in an MR element with excellent heat resistance. For this reason, MR elements with excellent heat resistance are suitable for application to various magnetic devices.

[0052] In addition to the above-mentioned effects, the ferromagnetic material M-X can also provide the effects of reducing the demagnetizing field and suppressing the shift magnetic field. A magnetic layer containing the ferromagnetic material M-X has a lower saturation magnetization than a conventional magnetic layer made only of the element M, and therefore the demagnetizing field is smaller. A small demagnetizing field is particularly useful in a finely processed MR element (for example, an element area of ​​50 μm ２ In particular, the element area is 10 μm ２ This has the effect of reducing the magnetization reversal field (i.e., switching field) in the MR element described below. A low switching field is advantageous for reducing power consumption in devices such as MRAM.

[0053] Furthermore, the use of the ferromagnetic material M-X also makes it possible to reduce the so-called shift magnetic field. The shift magnetic field (Hint) is generated by local ferromagnetic coupling (orange peel coupling) of the magnetic poles between the first magnetic layer 1 and the second magnetic layer 3, which are stacked via the nonmagnetic insulating layer 2, and this local ferromagnetic coupling is induced by unevenness at the interface. By using the above ferromagnetic material as the material for the free magnetic layer or the pinned magnetic layer, the magnetic poles are weakened and the interface is smoothed compared to when a conventional magnetic layer consisting only of the element M is used, resulting in the suppression of the shift magnetic field.

[0054] In order to improve the soft magnetic properties by reducing the demagnetizing field and suppressing the shift magnetic field, it is preferable that the atomic ratio a of the non-magnetic element is in the range of 5 to 60. From the viewpoint of reducing the demagnetizing field, the atomic ratio a is particularly preferably in the range of 15 to 60, and from the viewpoint of suppressing the shift magnetic field, it is advantageous to set the range of 10 to 60.

[0055] In the MR element, the number of stacked magnetic layers and non-magnetic insulating layers is not particularly limited. For example, non-magnetic insulating layers and magnetic layers may be stacked alternately in the configuration of the MR element 100 shown in FIG. 1. Even when the number of stacked magnetic layers and non-magnetic insulating layers is increased, the effect of improving characteristics can be obtained by using the ferromagnetic material M-X as a part of at least one magnetic layer.

[0056] Furthermore, an antiferromagnetic layer may be stacked on the magnetic layer to increase the magnetization reversal field of the magnetic layer. For example, as shown in FIG. 2, an MR element 100A may be configured by adding an antiferromagnetic layer 8 to the MR element 100 shown in FIG. 1. In this case, the antiferromagnetic layer 8 is provided in contact with the first magnetic layer 1, which is the pinned magnetic layer. The exchange bias magnetic field between the first magnetic layer 1 and the antiferromagnetic layer 8 causes the first magnetic layer 1, which is the pinned magnetic layer, to exhibit anisotropy in one direction, increasing its reversal field. In this way, the difference between parallel and antiparallel magnetization of the magnetic layer becomes clear, making it possible to obtain a stable output.

[0057] The antiferromagnetic layer 8 is preferably made of an Mn-based antiferromagnetic material (an Mn-containing antiferromagnetic material) such as Pt—Mn, Pd—Pt—Mn, Fe—Mn, Ir—Mn, or Ni—Mn. Ta, Nb, Hf, Zr, Cr, Pt, Cu, or Pd may also be used as an underlayer for the antiferromagnetic layer 8. In this case, Ni—Fe, Ni—Fe—Cr, or the like may be disposed as an underlayer to enhance the crystal orientation of the antiferromagnetic layer 8.

[0058] 3, the first magnetic layer 1B, which is the pinned magnetic layer, may be a multilayer film formed by stacking a first magnetic film 11, a second magnetic film 13, a non-magnetic film 14, and a third magnetic film 15 in this order, as viewed from the non-magnetic insulating layer 2 side. By appropriately adjusting the thickness of the non-magnetic film 14, antiferromagnetic exchange coupling occurs between the second magnetic film 13 and the third magnetic film 15. A multilayer film in which magnetic films are antiferromagnetically exchange coupled via a non-magnetic film is called a synthetic ferrimagnetic film. The non-magnetic film 14 in the synthetic ferrimagnetic film is preferably made of at least one material selected from Cr, Cu, Ag, Au, Ru, Ir, Re, Os, and alloys and oxides thereof. The thickness of the non-magnetic film 14 is preferably 0.2 to 1.2 nm.

[0059] 3, the first magnetic layer 1B, which is the pinned magnetic layer, may be a multilayer film configured of a third magnetic film 15, which is a ferromagnetic material M-X layer, a non-magnetic film 14, which is a laminated ferrimagnetic non-magnetic layer, a second magnetic film 13, which is a magnetic layer with a relatively large coercive force, and a first magnetic film 11, which is a Co—Fe—B layer; or a multilayer film configured of the third magnetic film 15, which is a ferromagnetic material M-X layer (a magnetic layer with a relatively large coercive force), a non-magnetic film 14, which is a laminated ferrimagnetic non-magnetic layer, and a first magnetic film 11, which is a Co—Fe—B layer, excluding the second magnetic film 13; or a multilayer film configured of the third magnetic film 15, which is a magnetic layer with a relatively large coercive force, a non-magnetic film 14, which is a laminated ferrimagnetic non-magnetic layer, a second magnetic film 13, which is a ferromagnetic material M-X layer, and a first magnetic film 11, which is a Co—Fe—B layer.

[0060] As described above, by using a multilayer film in which two magnetic films are stacked with a non-magnetic film sandwiched between them, and the magnetization directions of the magnetic films facing each other via the non-magnetic film are anti-parallel in zero magnetic field, the demagnetizing field can be reduced when the MR element is miniaturized, resulting in good magnetic field response.

[0061] 3, a high-coercivity magnetic film may be used in place of the second magnetic film 13, the non-magnetic film 14, and the third magnetic film 15. As the high-coercivity magnetic film, it is preferable to use a material with a coercivity of 100 Oe or more (approximately 7.96 kA / m or more), such as Co—Pt, Co—Cr—Pt, Co—Ta—Pt, Co—Sm, or Fe—Tb.

[0062] Alternatively, the MR element may be a spin-valve element using a synthetic ferrimagnetic pinned layer, such as the MR element 100C shown in Fig. 4. The MR element 100C shown in Fig. 4 has a configuration in which an antiferromagnetic layer 8 is stacked on the first magnetic layer 1B, which is the pinned magnetic layer shown in Fig. 3. This MR element 100C can achieve a stronger bias magnetic field than an MR element including only the antiferromagnetic layer 8.

[0063] The second magnetic film 13 and the third magnetic film 15 may be magnetostatically coupled rather than antiferromagnetically coupled. When the second magnetic film 13 and the third magnetic film 15 are magnetostatically coupled, the material of the non-magnetic film 14 is not particularly limited as long as it is a non-magnetic material, but the film thickness of the non-magnetic film 14 usually needs to be 2 nm or more (e.g., 3 nm or less).

[0064] The MR element may also have a dual spin valve structure in which pinned magnetic layers are disposed on both sides of the free magnetic layer. Specifically, as shown in FIG. 5 , the MR element 100D may have a structure in which a first magnetic layer 1 and a third magnetic layer 5 are disposed on both sides of a second magnetic layer 3, which is a free magnetic layer. A nonmagnetic insulating layer 2 is disposed between the first magnetic layer 1 and the second magnetic layer 3, and a nonmagnetic insulating layer 4 is disposed between the second magnetic layer 3 and the third magnetic layer 5. The nonmagnetic insulating layers 2 and 4 are tunnel insulating layers. The MR element 100D further includes antiferromagnetic layers 8a and 8b to fix the magnetization directions of the first magnetic layer 1 and the third magnetic layer 5.

[0065] In this way, the MR element 100D in which the nonmagnetic insulating layers 2 and 4 are made of tunnel insulating layers has a dual spin valve structure, and although the MR ratio does not change significantly, the presence of two barriers improves the bias voltage dependency.

[0066] As described above, the second magnetic layer 3, which is the free magnetic layer, may be a single layer or a multilayer film. When the second magnetic layer 3 is a multilayer film, the second magnetic layer 3 may be a multilayer film composed of a Co—Fe—B layer (or Co—Fe—B layer) / a magnetic layer with a relatively small coercive force, as viewed from the nonmagnetic insulating layer 2 side, a multilayer film composed of a ferromagnetic material Co—Fe—B layer / M-X layer, or a multilayer film composed of a Co—Fe—B layer / a ferromagnetic material M-X layer / a magnetic layer with a relatively small coercive force.

[0067] The second magnetic layer 3, which is the free magnetic layer, may be a multilayer film having a synthetic ferrimagnetic structure. In this case, the second magnetic layer 3 may be a multilayer film configured, as viewed from the nonmagnetic insulating layer 2 side, of a Co—Fe—B layer / synthetic ferrimagnetic nonmagnetic layer / magnetic layer with low coercivity, or a multilayer film configured of a Co—Fe—B layer / magnetic layer with low coercivity / synthetic ferrimagnetic nonmagnetic layer / ferromagnetic material M-X layer, or a multilayer film configured of a Co—Fe—B layer / ferromagnetic material M-X layer / synthetic ferrimagnetic nonmagnetic layer / magnetic layer with low coercivity.

[0068] 6 , the MR element may have a structure in which a synthetic ferrimagnetic pinned magnetic layer is disposed adjacent to the antiferromagnetic layer, and a synthetic ferrimagnetic free magnetic layer is disposed on the opposite side of the synthetic ferrimagnetic pinned magnetic layer with a non-magnetic insulating layer sandwiched therebetween (i.e., a synthetic ferrimagnetic structure is also provided on the free magnetic layer side). Specifically, as in the MR element 100E shown in FIG. 6 , a structure in which a first magnetic layer 1B, which is a synthetic ferrimagnetic pinned magnetic layer composed of a first magnetic film 11, a second magnetic film 13, a non-magnetic film 14, and a third magnetic film 15, is stacked adjacent to the antiferromagnetic layer 8, and a second magnetic layer 3E, which is a synthetic ferrimagnetic free magnetic layer composed of a fourth magnetic film 16, a fifth magnetic film 17, a non-magnetic film 18, and a sixth magnetic film 19, is stacked on the opposite side of the first magnetic layer 1B (synthetic ferrimagnetic pinned magnetic layer) with a non-magnetic insulating layer 2 sandwiched therebetween. In the MR element 100E, the magnetization directions of the magnetic films that face each other via a non-magnetic film are anti-parallel in zero magnetic field, so that the demagnetizing field can be reduced when the MR element 100E is miniaturized, resulting in even better magnetic field response.

[0069] A laminated ferrimagnetic free magnetic layer using a soft magnetic material with low saturation magnetization, such as NiFe, may be used as part of the second magnetic layer 3E, which is a free magnetic layer. Also, the MR element 100D, which is a dual spin-valve element shown in FIG. 5, may be configured to include the laminated ferrimagnetic free magnetic layer shown in FIG.

[0070] The thin films constituting the MR element can be formed by various sputtering methods, molecular beam epitaxy (MBE), ion plating, or the like.

[0071] Examples of sputtering methods include pulsed laser deposition (PLD), ion beam deposition (IBD), cluster ion beam, radio frequency (RF), direct current (DC), electron cyclotron resonance (ECR), helicon, inductively coupled plasma (ICP), facing targets, etc. Note that instead of these physical vapor deposition (PVD) methods, chemical vapor deposition (CVD), plating, sol-gel methods, etc. may also be used.

[0072] As an example, a method for producing a ferromagnetic material M-X will be described using a sputtering method. In this case, the ferromagnetic material M-X can be produced by depositing a film on an alloy target whose composition is determined taking into account the deviation from the desired composition of the magnetic element M. The target for the magnetic element M and the target for the non-magnetic element X may be sputtered simultaneously or alternately. Alternatively, reactive sputtering may be performed by introducing a portion of the non-magnetic element X in a gaseous state into the sputtering apparatus. The ferromagnetic material M-X may also be produced using an alloy target whose composition is determined taking into account the deviation from the desired composition that depends on the film-forming conditions (sputtering gas type, gas pressure, input power, etc.).

[0073] Next, a method for producing a non-magnetic insulating layer mainly composed of MgO or a non-magnetic insulating layer mainly composed of fluorine-added MgO with a controlled amount of fluorine will be described using a sputtering method as an example. In this case, two types of sputtering cathodes are used in the same vacuum chamber, and a pure MgO target is placed on one sputtering cathode and an MgF target is placed on the other sputtering cathode. ２ On-chip MgO target (MgF on a pure MgO target) ２ The RF cathode power was 0 to 150 W in an Ar gas atmosphere, and the input power of the pure MgO target was changed in the range of 0 to 150 W. ２ By varying the input power of the on-chip MgO target in the range of 0 W to 50 W, a non-magnetic insulating layer containing fluorine-added MgO as its main component can be produced.

[0074] Furthermore, to fabricate a magnetic device including an MR element that passes a current perpendicular to the film surface, microfabrication can be performed by combining physical or chemical etching methods such as ion milling, RIE (Reactive Ion Etching), and FIB (Focused Ion Beam), and photolithography techniques using a stepper for forming fine patterns, EB (Electron Beam) method, and the like.

[0075] As described above, the MR element according to this embodiment can realize a magnetoresistive element (MR element) that exhibits excellent heat resistance even after heat treatment at 350° C. or higher when MgO or fluorine-added MgO is used as the main component material of the nonmagnetic insulating layer laminated on the magnetic layer. In other words, the MR element according to this embodiment exhibits excellent heat-resistant MR characteristics even after high-temperature heat treatment. The reason for this is not entirely clear at present, but it is thought that the addition of nonmagnetic element X to the magnetic layer and fluorine to the nonmagnetic insulating layer not only mitigates the effects of atomic diffusion at the magnetic layer / nonmagnetic insulating layer interface, but also stabilizes the interface through a favorable combination with the nonmagnetic insulating layer.

[0076] An MR element having such characteristics is suitable for application to various magnetic devices. Magnetic devices including MR elements of various configurations according to the above embodiments will now be described with reference to FIGS. 7 to 12B.

[0077] First, a magnetic device 200, which is an MR element with electrodes arranged thereon, will be described with reference to Fig. 7. The magnetic device 200 shown in Fig. 7 includes a substrate 21, and a lower electrode 22, an MR element 23, and an upper electrode 24 arranged on the substrate 21. The lower electrode 22, the MR element 23, and the upper electrode 24 are stacked in this order on the substrate 21. An interlayer insulating film 25 is also arranged around the element between the lower electrode 22 and the upper electrode 24. In this magnetic device 200, a current is passed through the MR element 23 sandwiched between the upper electrode 24 and the lower electrode 22, and a voltage is read.

[0078] Furthermore, in the case of a magnetic device having an MR element in which a current flows in a direction perpendicular to the film surface, it is advisable to further arrange a pair of electrode layers sandwiching the magnetic device in this direction.

[0079] It is advisable to flatten the surfaces of the electrodes and the like included in the magnetic device by polishing such as CMP (Chemical Mechanical Polishing) or by cluster ion beam etching.

[0080] Suitable materials for the lower electrode 22 and the upper electrode 24 include low-resistance metals such as Pt, Au, Cu, Ru, and Al. Suitable insulating materials for the interlayer insulating film 25 include Al. ２ O ３ , SiO ２ Materials with excellent insulating properties such as the above are suitable.

[0081] Next, an example of a magnetic device 200A, which is a magnetoresistive magnetic head using the MR element according to the above embodiment, will be described with reference to FIG. 8. The magnetoresistive magnetic head shown in FIG. 8 includes an upper shield 35 and a lower shield 31 as two magnetic shields made of magnetic material, and an MR element 33. The upper shield 35 and the lower shield 31 restrict the introduction of magnetic fields other than the magnetic field to be detected by the MR element 33 into the MR element 33. The MR element 33 is disposed within the read gap length of the upper shield 35 and the lower shield 31. Also disposed within the read gap length of the upper shield 35 and the lower shield 31 are a pair of electrodes 32 and 34 sandwiching the MR element 33 therebetween.

[0082] Recording and reproducing magnetic information using the magnetic device 200A (magnetoresistive magnetic head) configured as described above is performed as follows: A current is passed through the winding 37, and a signal is written to the recording medium by a leakage magnetic field from the recording gap between the recording pole 38 and the upper shield 35. This allows magnetic information to be recorded. An insulating film 36 is formed in the recording gap, and the gap length corresponds to the film thickness of the insulating film 36. Reproduction is performed by reading the signal magnetic field from the recording medium with the MR element 33 provided in the reproduction gap (shield gap).

[0083] The read head may have a narrow gap by omitting electrodes from the MR element 33 by configuring the upper shield 35 and the lower shield 31 to also serve as the upper and lower electrodes of the MR element 33 .

[0084] Furthermore, the MR element 43 may be applied to a magnetoresistive magnetic head having a magnetic flux guide (yoke) made of a magnetic material, as in the magnetic device 200B shown in Fig. 9. In the magnetic device 200B shown in Fig. 9, yokes 41a and 41b introduce the magnetic field to be detected into the MR element 43. The yoke 41a is an upper yoke located above the MR element 43, and the yoke 41b is a lower yoke located below the MR element 43. The yokes 41a and 41b also serve as magnetic shields. The lower yoke, yoke 41b, also serves as a lower lead.

[0085] In the magnetic device 200B, a current for detecting a signal magnetic field flows between the upper lead 44 and the yoke 41b, which also serves as the lower lead. Note that the entire free layer of the MR element 43 or a part thereof may also serve as the yokes 41a and 41b.

[0086] The magnetic devices 200A and 200B, which are magnetoresistive magnetic heads shown in Figures 8 and 9, can be applied to magnetic recording devices such as HDDs. As shown in Figure 10, for example, an HDD includes a magnetic head 71, an arm 72 that supports the magnetic head, a drive unit 73 that drives the arm 72 and the disk, a signal processing unit 74, and a magnetic recording medium (magnetic disk) 75 that records / reproduces signals using the magnetic head 71.

[0087] Next, an example of a magnetic device 200C, which is a memory element using the MR element according to the above embodiment, will be described with reference to FIG. 11 . The magnetic device 200C shown in FIG. 11 is an MRAM and includes an MR element 61, a plurality of bit lines 62 (sense lines), and a plurality of word lines 63. The MR elements 61 are arranged at each intersection of the bit lines 62 and the word lines 63. Therefore, the MR elements 61 are arranged in a matrix. The bit lines 62 and the word lines 63 are metal lines made of a metal material such as Cu or Al. The bit lines 62 are information read conductor lines that read information recorded in the MR elements 61, and the word lines 63 are information recording conductor lines that record information in the MR elements 61. A signal is recorded in the MR element 61 by a composite magnetic field generated when a signal current is passed through the bit lines 62 and the word lines 63. Specifically, the signal is recorded in an element (MR element 61a in FIG. 11) arranged at the intersection of the lines where the transistors are turned on (two-current coincidence method).

[0088] Next, an example of a magnetic device 200D, which is a magnetic sensor using the MR element according to the above embodiment, will be described with reference to FIGS. 12A and 12B. As shown in FIG. 12A, the magnetic device 200D, which is a magnetic sensor, includes an MR element. In the magnetic device 200D (magnetic sensor), the MR element detects the rotation of a magnetic rotating body 80. For example, if the magnetic rotating body 80 has a magnet, the MR element detects changes in the magnetic field of the magnet in response to the rotation of the magnetic rotating body 80. In other words, the MR element is rotated relative to the magnet that generates the magnetic field. Although not shown, the magnetic device 200D may be provided with a yoke for guiding the magnetic field to the MR element.

[0089] Furthermore, the magnetic device 200D, which is a magnetic sensor, has a detection means for detecting the rotation of the magnetic rotating body 80 (i.e., a detection means for detecting the magnetic field). An example of such a detection means is the bridge circuit 300 shown in FIG. 12B. It is preferable to arrange the MR elements of the above-described embodiment in at least some of the four bridge resistor sections 90, 91, 92, and 93 that make up the bridge circuit 300. It is also possible to arrange MR elements in all of the bridge resistor sections. In the bridge circuit 300, an output signal indicating a change in the magnetic field is measured via a differential amplifier 94.

[0090] Examples The MR element according to the present embodiment will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the following examples, MR elements having the configurations described in each example were fabricated on a silicon substrate (φ3 inches) with a thermal oxide film by multi-target magnetron sputtering, and the MR characteristics and the like were investigated.

[0091] (Example 1) First, Example 1 will be described. In Example 1, an MR stacked film was formed, which was composed of a thermally oxidized Si substrate / Ta(3) / Cu(200) / Ta(3) / Pt-Mn(30) / Co-Fe(1) / ferromagnetic material M-X(2) / Co-Fe-B(3) / Mg-O-F(2.0) / Co-Fe-B(2) / Co-Fe(3) / Ta(15). Here, the numbers in parentheses indicate the film thickness. The unit of film thickness is "nm" (hereinafter, film thickness will be expressed in the same manner).

[0092] First, a metal multilayer film of Ta / Cu / Ta / Pt—Mn / Co—Fe / MX / Co—Fe—B was formed on a Si substrate with a thermal oxide film (hereinafter simply referred to as “substrate”) by the following procedure.

[0093] First, the substrate surface was subjected to ultrasonic cleaning using pure water and ultraviolet (UV) ozone cleaning. Ultrasonic cleaning removes dust (particles originating from the substrate) generated during substrate separation. UV ozone cleaning removes organic matter adhering to the substrate. Ultrasonic cleaning and UV ozone cleaning were repeated two or more times. By performing these processes two or more times, it is possible to achieve cleaning with little variation. Furthermore, reverse sputtering was performed on the substrate surface. This removes impurities adhering to the substrate surface and improves adhesion between the substrate and the metal multilayer film formed on the substrate.

[0094] Next, the substrate was set in a magnetron sputtering device (manufactured by Hirano Koon Co., Ltd.), and the vacuum level was set to 5×10 －７ The pressure in the chamber was reduced to below 100 Torr. Next, Ar gas was introduced into the chamber as a working gas at a flow rate of 60 ccm, and the chamber was maintained in an Ar atmosphere at a pressure of 10 mTorr. In this state, RF power (30 W) was applied to the substrate, and the substrate was reverse sputtered for 5 minutes. During this process, positive Ar ions generated in the chamber collided with the surface of the substrate, thereby reverse sputtering the substrate surface.

[0095] Next, a metal multilayer film was formed on the reverse sputtering surface of the substrate using a four-target magnetron sputtering device (manufactured by Hirano Koon Co., Ltd.) and a nine-target helicon magnetron sputtering device (manufactured by ULVAC, Inc.).

[0096] Specifically, first, Ta / Cu / Ta were formed in this order on a substrate using a magnetron sputtering device. The Ta film was formed in an Ar atmosphere at a pressure of 4 mTorr, using a metallic Ta target, and RF input power to the target was 100 W. The Cu film was formed in an Ar atmosphere at a pressure of 2 mTorr, using a metallic Cu target, and DC applied voltage to the target was 425 V and target current was 0.21 A.

[0097] Next, the Ta film was etched by 2 nm by electron cyclotron resonance (ECR) cleaning. The ECR cleaning was performed under the following conditions: the Ar gas flow rate for generating Ar ions was 2 ccm; the microwave power for converting Ar into a plasma state was 300 W (detector output current 150 μA); the voltage for extracting and accelerating Ar ions was 100 V, and the voltage for controlling the ion spread was 500 V.

[0098] Next, a PtMn / Co antiferromagnetic layer was formed on the Ta film, which was the top layer of the Ta / Cu / Ta metal multilayer film. ９０ Fe １０ / M-X / Co ４０ Fe ４０ B ２０ The above metal multilayer films were formed in this order.

[0099] Each film in this metal multilayer film was formed under the following conditions.

[0100] Ta film: Ar atmosphere with a pressure of 0.8 Pa, metal Ta target, RF coil output of 5 W, RF cathode output of 65 W PtMn film: Ar atmosphere with a pressure of 1.01 Pa, PtMn target, DC cathode voltage of 450 V Co ９０ Fe １０ Film: Ar atmosphere at a pressure of 0.8 Pa, Co ９０ Fe １０ Target, DC cathode voltage 400V M-X film: Ar atmosphere with a pressure of 0.8 Pa, various M-X targets, DC cathode voltage 400V Co ４０ Fe ４０ B ２０ Film: Ar atmosphere at a pressure of 0.8 Pa, Co ４０ Fe ４０ B２０ Target, RF coil output 50W, DC cathode voltage 400V Next, PtMn / Co ９０ Fe １０ / M-X / Co ４０ Fe ４０ B ２０ On the metal multilayer film, a MgO insulator layer (tunnel barrier) with a controlled amount of fluorine was formed as a non-magnetic insulating layer. ２ The non-magnetic insulating layer was formed using an "on-chip target" with a chip attached. At this time, the surface uniformity of the non-magnetic insulating layer was improved by rotating the substrate. ２ Three chips (manufactured by Kojundo Chemical Laboratory Co., Ltd., size 5 mm x 5 mm x thickness 2 mm) were attached and used as targets.

[0101] As an example of the conditions for forming the nonmagnetic insulating layer, an RF coil output of 50 W, an RF cathode power of 0 to 150 W, and an Ar gas atmosphere with a pressure of 4.05 Pa were used. As shown in Table 1, the amount of fluorine in the nonmagnetic insulating layer was controlled by varying the power input to the pure MgO target in the range of 0 W to 150 W and by varying the power input to the on-chip target in the range of 0 W to 50 W. As a result, as shown in Table 1 below, it is possible to form a nonmagnetic insulating layer made of only MgO with no fluorine added (pattern X1 in Table 1), and also to form nonmagnetic insulating layers made of fluorine-added MgO with different amounts of fluorine (patterns X2 to X5 in Table 1).

[0102]

[0103] Next, Co--Fe--B / Co--Fe / Ta was formed on the non-magnetic insulating layer in the same manner as in the above-mentioned metal multilayer film.

[0104] The MR stacked film was then processed into a mesa shape as shown in Figure 7, followed by the formation of a Cu(150) / Ta(3) upper electrode to fabricate an MR element. The MR element was then heat-treated at 280°C in a 5 kOe magnetic field for 3 hours to impart unidirectional anisotropy to the Pt-Mn in the MR element. The element area of ​​the MR element thus obtained was, for example, 2 μm x 3 μm, but MR elements with sizes ranging from 2 μm x 2 μm to 32 μm x 32 μm were also fabricated.

[0105] This MR element is a spin-valve type TMR element having a configuration similar to that shown in Figure 2, and a ferromagnetic material M-X is used in part of the first magnetic layer 1, which is the pinned magnetic layer. A magnetic field of up to 5 kOe was applied to this MR element, and the MR characteristics were examined using the DC four-terminal method. The MR ratio was calculated using the following equation.

[0106] MR ratio={(Rmax−Rmin) / Rmin}×100(%) where Rmax is the maximum resistance value and Rmin is the minimum resistance value (the same applies hereinafter).

[0107] The MR ratio varies depending on the material, manufacturing method, and film thickness of the non-magnetic insulating layer, which is the tunnel insulating layer. It is also affected by the material and film thickness of the films that make up the MR element, as well as the manufacturing process of the MR element. Therefore, the characteristics of the MR element are evaluated based on the characteristics of a conventional element manufactured in the same manner except that a material containing only the magnetic element M in the ferromagnetic material M-X is used. This also applies to the following examples. Table 2 below shows the measurement results of the MR ratio for various samples of ferromagnetic material M-X with different materials and compositions.

[0108]

[0109] Although not specified in Table 2, MR elements other than the conventional and comparative examples are considered examples (the same applies hereinafter). Specifically, in Table 2, sample a01 is the conventional example, and samples a02, a10, a16, and a21 are comparative examples. The other samples a03 to a09, a11 to a15, a17 to a20, and a22 to a27 are examples.

[0110] As shown in Table 2, all of the MR elements of the examples can achieve a higher MR ratio than the conventional sample a01. It can also be seen that some of the MR elements of the examples achieve an extremely high MR ratio of 50% or more. The reason for this increase in MR ratio is thought to be that the addition of a nonmagnetic element to Fe increases the spin polarization.

[0111] Next, the prepared samples a01 to a27 were subjected to heat treatment. Specifically, the samples were subjected to vacuum heat treatment (1×10 －６ Each sample was heated to 450°C under a pressure of 1000kJ / cm² (less than 1000kJ / cm²). The temperature profile was as follows: First, the sample was heated from room temperature to the target heat treatment temperature over a period of 2 hours, the target heat treatment temperature (450°C) was maintained for 1.5 hours, and then the sample was cooled to room temperature over a period of approximately 5 hours.

[0112] The results of the heat treatment of each sample are shown in Figures 13A to 13D. In Figures 13A to 13D, the horizontal axis represents temperature (°C) and the vertical axis represents the relative value of the MR ratio.

[0113] 13A to 13D, it can be seen that the MR ratio of sample a01 of the conventional example decreased rapidly with increasing heat treatment temperature, and that the MR ratio of sample a02 of the comparative example also decreased rapidly with increasing heat treatment temperature, as shown in FIG.

[0114] In contrast, as shown in Figures 13A to 13D, the samples of the example exhibited excellent thermal stability. １００－ａ X １ ａ Among these, X １ It can be seen that when the content exceeds 60, the thermal stability is suddenly lost. １ It is clear that the addition of elements improves stability against heat treatment, particularly at high temperatures. １ The content of the element is preferably 0.05 or more, more preferably 5 or more. １It was found that by setting the content of the element within the range of 1 to 60, the decrease in the MR ratio during heat treatment up to 450°C was suppressed.

[0115] Next, for each of the above samples a06, a07, a13, a18, and a24, samples were prepared by using MgO with different amounts of fluorine added as the nonmagnetic insulating layer, and the samples were similarly evaluated.

[0116] The structure of each sample is shown in Table 3 below. In sample a06, samples b01, b02, b03, and b04 are obtained by adding fluorine to MgO, in sample a07, samples b05 and b06 are obtained by adding fluorine to MgO, in sample a13, samples b07 and b08 are obtained by adding fluorine to MgO, in sample a18, samples b09 and b10 are obtained by adding fluorine to MgO, and in sample a24, samples b11 and b12 are obtained by adding fluorine to MgO.

[0117]

[0118] The results of the heat treatment for each sample shown in Table 3 are shown in FIGS. 14A to 14E.

[0119] 14A to 14E, it was found that even in samples in which fluorine-doped MgO was used as the nonmagnetic insulating layer, a preferable combination of the nonmagnetic insulating layer and the ferromagnetic material M-X made it possible to suppress a decrease in the MR ratio even when heat treatment was performed at temperatures up to 450° C. Furthermore, the effective amount of fluorine added obtained by combining with the ferromagnetic material M-X was 0.005 atm % or more and 0.15 atm % or less, and more preferably 0.005 atm % or more and 0.05 atm % or less.

[0120] Example 2 Next, Example 2 will be described. In Example 2, an MR stacked film was formed consisting of a thermally oxidized Si substrate / Ta(3) / Cu(200) / Ta(3) / Pt—Mn(20) / Co—Fe(1) / ferromagnetic material M-X(2) / Ru(0.9) / Co—Fe—B(2) / Mg—O—F(2.0) / Co—Fe—B(2) / ferromagnetic material M-X(1) / Ru(0.9) / Ni—Fe(5) / Ta(15). The fluorine content of the Mg—O—F layer was 0.5 atm %.

[0121] The MR element was fabricated by processing the MR laminated film into a mesa shape and then forming a Cu(150) / Ta(3) upper electrode on the mesa, as in Example 1. The MR element was then heat-treated at 280°C in a 5 kOe magnetic field for 3 hours to impart unidirectional anisotropy to the Pt—Mn in the MR element.

[0122] The MR element thus obtained is a spin-valve type TMR element having a pinned magnetic layer and a free magnetic layer with a laminated ferrimagnetic structure according to Fig. 6. The ferromagnetic materials M-X of three types of samples c01, c02, and c03 relating to this MR element are shown in Table 4.

[0123]

[0124] The MR ratios of the MR elements of these three samples were examined in the same manner as in Example 1, and the results are shown in FIG.

[0125] As shown in Figure 15, by using the ferromagnetic material M-X for the pinned magnetic layer and free magnetic layer of the laminated ferrimagnetic structure and by using fluorine-added MgO for the non-magnetic insulating layer, it was found that an MR element with excellent MR characteristics can be obtained even after heat treatment up to 450°C by using an appropriate combination of the two.

[0126] Example 3 Next, Example 3 will be described. In Example 3, an MR stacked film was formed, which was composed of a thermally oxidized Si substrate / Ta(3) / Cu(200) / Ta(3) / Pt—Mn(20) / Co—Fe(2) / ferromagnetic material M-X(3) / Mg—O—F(2.0) / ferromagnetic material M-X(2) / Ni—Fe(3) / Ta(15). The fluorine content of the Mg—O—F layer was set to 0.5 atm %.

[0127] The MR element was fabricated by processing the MR laminated film into a mesa shape, followed by forming a Cu(150) / Ta(3) upper electrode, as in Example 1. The MR element was then heat-treated at 280°C in a 5 kOe magnetic field for 3 hours to impart unidirectional anisotropy to the Pt-Mn.

[0128] The MR element thus obtained is a spin-valve type TMR element according to Fig. 2. Table 5 shows the ferromagnetic materials M-X of three samples d01, d02, and d03 relating to this MR element.

[0129]

[0130] The MR ratios of the MR elements of these three samples were examined in the same manner as in Example 1, and the results are shown in FIG.

[0131] As shown in FIG. 16, by using the ferromagnetic material M-X for the pinned magnetic layer and the free magnetic layer, and by using fluorine-doped MgO for the non-magnetic insulating layer, it was found that an MR element having excellent MR characteristics can be obtained even after heat treatment up to 450°C by using an appropriate combination of the two.

[0132] Example 4 Next, Example 4 will be described. In Example 4, a magnetoresistive magnetic head having a yoke structure shown in FIG. 8 was fabricated using an MR laminated film (TMR film) of the samples a06 and b02 of the example fabricated in Example 1 and the conventional sample a01. The material of the upper shield 35 and the lower shield 31 was Ni. ０．８ Fe ０．２ A plated alloy was used. In Example 4, after the Ni--Fe constituting the bottom shield 31 was polished by CMP, the TMR film structure was formed in a manner opposite to that of the above embodiment. Specifically, a Co--Fe film was formed, and finally a Pt--Mn film was formed, and an electrode film (Au) was formed on top of this. The element size of the read head was 1 μm×1.5 μm. After the element was formed, a vacuum heat treatment (1×10 －６ A direct current was passed through the fabricated magnetic head as a sense current, and an alternating current signal magnetic field of about 50 Oe was applied to evaluate the output of the magnetic head. The results are shown in Table 6.

[0133]

[0134] As shown in Table 6, it was found that the output of the magnetic head using samples a06 and b02 was approximately 10 times larger than the output of the magnetic head using sample a01 of the conventional example.

[0135] (Example 5) Next, Example 5 will be described. In Example 5, an integrated memory was fabricated by integrating MR elements (memory elements) as shown in FIG. 11 on a CMOS substrate. The MR elements were arranged in eight blocks, each block consisting of 16 x 16 MR elements. After the memory element formation, the element was subjected to vacuum heat treatment at 400°C (1 x 10 －６ Torr or less) was carried out. The TMR elements used were the sample a06 of the embodiment fabricated in Example 1 and the sample a01 of the conventional example. The cross-sectional area of ​​the memory element of each sample was 1 μm × 1.5 μm. Furthermore, one of the memory elements in each block was a dummy element to cancel the wiring resistance, the minimum element resistance, and the FET resistance. The word lines and bit lines were Cu wiring made of Cu.

[0136] The combined magnetic field from the word line and bit line simultaneously reversed the magnetization of the free magnetic layer in each of the eight memory elements in the eight blocks, recording eight bits of data. Next, the gates of the CMOS-fabricated FETs were turned on for one memory element in each block, allowing a sense current to flow. The voltages generated in the bit line, memory element, and FET in each block were compared with a dummy voltage by a comparator, and eight bits of information were simultaneously read from the output voltages of each memory element. The output of the memory element using the TMR element of the example was approximately 20 times that of the TMR element of the comparative example.

[0137] Example 6 Next, Example 6 will be described. In Example 6, an MR element was fabricated using an MR stacked film (TMR film) of Example sample a06 fabricated in Example 1 and Conventional sample a01. This MR element was incorporated into the bridge circuit shown in FIG. 12B. In this case, the MR element was provided on a Si substrate with a thermal oxide film, and bridge resistors 90, 91, 92, and 93 were composed of the same MR element and wired on a board to form a bridge circuit. A magnetic sensor having such a bridge circuit was placed close to the magnetic rotating body 80 shown in FIG. 12A in an arrangement where an AC signal magnetic field of approximately 50 Oe was applied, and the output of the magnetic sensor was evaluated. The output of the magnetic sensor constructed with Example sample a06 was approximately twice the output of the magnetic sensor constructed with Conventional sample a01. In addition, after fabrication of the MR element, a vacuum heat treatment (1×10) was performed at 400°C in a magnetic field-free environment. －６ Torr or less), the magnetic sensor made of sample a06 of the embodiment produced approximately 10 times the output of the magnetic sensor made of sample a01 of the conventional example.

[0138] The above describes the magnetoresistive element according to the present embodiment and the magnetic device using the magnetoresistive element based on the embodiments and examples, but the present invention is not limited to the above embodiments and examples.

[0139] For example, the present invention also includes forms obtained by making various modifications to the above embodiments that a person skilled in the art would think of, and forms realized by arbitrarily combining the components and functions of the embodiments within the scope that does not deviate from the spirit of the present invention.

[0140] In addition, any combination of two or more claims from among the multiple claims described in the claims at the time of filing of this application, to the extent that there is no technical contradiction, is also included in the present invention. For example, when a dependent-form claim described in the claims at the time of filing of this application is made into a multiple claim or multiple multiple claim that cites all of the higher claims to the extent that there is no technical contradiction, all combinations of claims included in that multiple claim or multiple multiple claim are also included in the present invention. Note that all modifications that are equivalent in meaning and scope to the claimed invention are included in the present invention.

[0141] The magnetoresistive element of the present invention has a large MR ratio and excellent heat resistance compared to conventional magnetoresistive elements, and can be widely applied to various magnetic devices such as magnetoresistive magnetic heads, magnetic recording devices including such magnetoresistive magnetic heads, high-density magnetic memories (MRAMs), and magnetic sensors that detect external magnetic fields.

[0142] 1, 1B First magnetic layer 2, 4 Non-magnetic insulating layer 3, 3E Second magnetic layer 5 Third magnetic layer 8, 8a, 8b Antiferromagnetic layer 11 First magnetic film 13 Second magnetic film 14 Non-magnetic film 15 Third magnetic film 16 Fourth magnetic film 17 Fifth magnetic film 18 Non-magnetic film 19 Sixth magnetic film 21 Substrate 22 Lower electrode 23 MR element 24 Upper electrode 25 Interlayer insulating film 31 Lower shield 32, 34 Electrode 33 MR element 35 Upper shield 36 Insulating film 37 Winding portion 38 Recording pole 41a, 41b Yoke 43 MR element 44 Upper lead 61, 61a MR element 62 Bit line 63 Word line 71 Magnetic head 72 Arm 73 Drive portion 74 Signal processing unit 75 Magnetic recording medium (magnetic disk) 80 Magnetic rotating body 90, 91, 92, 93 Bridge resistor unit 94 Differential amplifier 100, 100A, 100B, 100C, 100D, 100E MR element (magnetoresistive element) 200, 200A, 200B, 200C, 200D Magnetic device 300 Bridge circuit

Claims

1. A magnetoresistance element that operates after undergoing a heat treatment at least equal to or higher than 350° C., comprising a multilayer film including two magnetic layers and a non-magnetic insulating layer disposed between the two magnetic layers, the magnetoresistance element has a resistance value that changes according to a relative angle between the magnetization directions in the two magnetic layers, one of the two magnetic layers is a free magnetic layer and the other of the two magnetic layers is a fixed magnetic layer, the magnetization of the free magnetic layer is relatively more likely to rotate by an external magnetic field than the magnetization of the fixed magnetic layer, the magnetoresistance element further comprises an antiferromagnetic layer that suppresses the magnetization rotation of the fixed magnetic layer, and at least one of the two magnetic layers is represented by the formula M １００－ａ X ａ The present invention includes a ferromagnetic material M-X represented by the formula: １ ｂ X ２ ｃ and X １ is at least one element selected from Ru, Rh, Pd, Ir, and Pt; X ２ a is at least one element selected from Cr and Mn, and a, b, and c are numerical values ​​satisfying the following formulae: 5≦a≦60, 0≦b≦60, 0≦c≦30, a=b+c, ​​and the nonmagnetic insulating layer is made of an insulating material containing magnesium oxide as a main component.

2. The magnetoresistance element according to claim 1, wherein the insulating material is composed mainly of magnesium oxide containing fluorine as a part of it.

3. The magnetoresistance element according to claim 2, wherein the amount of fluorine added in said nonmagnetic insulating layer is not less than 0.005 atm % and not more than 0.15 atm %.

4. The magnetoresistance element according to claim 2, wherein the amount of fluorine added in said nonmagnetic insulating layer is not less than 0.005 atm % and not more than 0.05 atm %.

5. X １ 5. The magnetoresistance element according to claim 1, wherein: is Pt; a is a value that satisfies 5≦a≦50; and c=0.

6. X １ 5. The magnetoresistance element according to claim 1, wherein is at least one selected from the group consisting of Pd, Rh and Ir, a is a value that satisfies 5≦a≦50, and c=0.

7. X １ is Pt, and X ２ The magnetoresistance element according to any one of claims 1 to 4, wherein b and c are numerical values ​​that satisfy the following formulae: 0<b<50, 0<c≦20, and 5≦a≦50.

8. The magnetoresistance element according to claim 1, wherein the free magnetic layer includes the ferromagnetic material M-X.

9. The magnetoresistance element according to claim 1, wherein the pinned magnetic layer includes the ferromagnetic material M-X.

10. A magnetoresistance element according to any one of claims 1 to 4, wherein the magnetic layer containing the ferromagnetic material M-X of the two magnetic layers is a multilayer film, at least one magnetic film contained in the multilayer film contains the ferromagnetic material M-X, and the magnetic film in contact with the non-magnetic insulating layer is made of a Co-Fe-B alloy.

11. Formula M １００－ａ X １ ｂ X ２ ｃ In the ferromagnetic material M-X represented by the formula {Co （１－ｘ） Fe ｘ } ０．８ B ０．２ 5. The magnetoresistance element according to claim 1, which is made of a Co-Fe-B alloy represented by the formula: where x is a value that satisfies the formula: 0.25≦x≦0.5, 5≦a≦20, 0≦b≦20, 0≦c≦10, and a=b+c.

12. A magnetoresistance element according to any one of claims 1 to 4, wherein the magnetic layer containing the ferromagnetic material M-X of the two magnetic layers includes a nonmagnetic metal layer and a pair of magnetic films sandwiching the nonmagnetic metal layer.

13. A magnetoresistance element according to any one of claims 1 to 4, further comprising a pair of electrode layers for passing a current perpendicular to the film surface.

14. The magnetoresistance element according to any one of claims 1 to 4, wherein the magnetoresistance element is operated after undergoing a heat treatment at least at 400°C or higher.

15. A magnetoresistive magnetic head comprising: a magnetoresistive element according to any one of claims 1 to 4; and a magnetic shield for restricting the introduction of magnetic fields other than the magnetic field to be detected by said magnetoresistive element into said magnetoresistive element.

16. A magnetoresistive magnetic head comprising: a magnetoresistive element according to any one of claims 1 to 4; and a yoke for introducing a magnetic field to be detected into said magnetoresistive element.

17. A magnetic recording device comprising the magnetoresistive magnetic head according to claim 15.

18. A magnetoresistive memory device comprising: a magnetoresistive element according to any one of claims 1 to 4; an information recording conductor wire for recording information in said magnetoresistive element; and an information reading conductor wire for reading out said information.

19. A magnetic sensor comprising the magnetoresistance element according to any one of claims 1 to 4, the magnetoresistance element being arranged rotated relative to a magnet that generates a magnetic field.

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