JP4962010B2 - Method for forming magnetoresistive effect element - Google Patents

Description

The present invention relates to a method for forming a magnetoresistive element that exhibits a giant magnetoresistive effect .

  In reproducing information from a magnetic recording medium such as a hard disk, a thin film magnetic head including an MR element exhibiting a magnetoresistive (MR) effect is widely used. In recent years, since the recording density of magnetic recording media has been increased, a thin film magnetic head using a giant magnetoresistive element (GMR element) exhibiting a giant magnetoresistive (GMR) effect is common. is there. An example of such a GMR element is a spin valve (SV) type GMR element.

  This SV type GMR element includes a magnetic layer (magnetization pinned layer) in which the magnetization direction is fixed in a fixed direction via a nonmagnetic intermediate layer, and a magnetic layer in which the magnetization direction changes in response to a signal magnetic field from the outside. (Magnetization free layer). A device configured such that a read current flows in the in-plane direction during the reproducing operation is particularly called a CIP (Current in Plane) -GMR element. Further, a thin film magnetic head provided with this is called a CIP-GMR head. In this case, the electrical resistance (that is, the voltage) changes when a read current is passed according to the relative angle of the magnetization direction in the two magnetic layers (the magnetization fixed layer and the magnetization free layer).

  Recently, a CPP having a CPP (Current Perpendicular to the Plane) -GMR element configured to allow a read current to flow in a direction perpendicular to the laminated surface during a reproducing operation in order to cope with further improvement in recording density. -Development of GMR heads is ongoing. Such a CPP-GMR head generally includes a GMR element and a pair of magnetic domain control layers disposed so as to face each other with the GMR element sandwiched in a direction corresponding to the track width direction via an insulating film. The upper and lower electrodes are formed so as to sandwich the GMR element and the pair of magnetic domain control layers along the stacking direction. The upper and lower electrodes also serve as upper and lower shield layers. The CPP-GMR head having such a configuration has an advantage that a high output can be obtained as compared with the CIP-GMR head when the dimension in the reproduction track width direction is reduced. That is, since the read current flows in the in-plane direction in the CIP-GMR head, as the size in the reproduction track width direction is narrowed, the magnetically sensitive portion through which the read current passes becomes minute and the amount of voltage change becomes small. . On the other hand, in the case of a CPP-GMR head, since a read current is passed in the stacking direction, there is little influence on the amount of voltage change due to narrowing in the reproduction track width direction. For this reason, the CPP-GMR head is more advantageous than the CIP-GMR head in terms of reducing the track density expressed by the number of tracks per inch (TPI; Tracks Per Inch). In addition, when compared with the CIP-GMR head, there is no need to provide an insulating layer between the CPP-GMR element and each of the upper shield film and the lower shield film. The expressed linear recording density can be reduced.

From such a background, the CPP-GMR head has been improved to cope with the further increase in recording density, and has, for example, a CPP-GMR element having a current-confined-path (CCP) structure. Have been proposed (see Patent Documents 1 and 2). This CCP-structured CPP-GMR element is a CCP layer in which an insulator such as aluminum oxide is dispersedly disposed on a base material made of a non-magnetic conductor such as copper, between the magnetization fixed layer and the magnetization free layer. Is provided. With such a structure, when a sense current flows in the stacking direction, a region in the in-plane direction through which the sense current flows is constricted in the CCP layer (a current confinement effect can be obtained), so that higher sensitivity can be obtained.
JP 2002-208744 A JP 2006-54257 A

  By the way, in forming the above-mentioned CPP-GMR element having the CCP structure, after forming a conductive layer such as copper, an oxide region is formed in a part thereof by performing an oxidation treatment by a natural oxidation method or a plasma oxidation method. The process of forming is generally necessary. However, the oxidation of the conductive layer often oxidizes a part of the underlying layer (for example, the magnetization pinned layer), and in such a case, the resistance change rate is deteriorated. . Therefore, a method capable of forming a CCP structure without adversely affecting the underlayer is desired.

  Further, when a CPP-GMR element having a CCP structure is exposed to, for example, a high temperature environment, the metal element moves from the adjacent magnetization fixed layer to the CCP layer. There is a possibility that the current confinement effect cannot be obtained. Therefore, a CPP-GMR element having a CCP structure capable of obtaining good sensitivity even in a high temperature environment is desired.

The present invention has been made in view of such problems, and a first object thereof is to provide a magnetoresistive effect element that can stably obtain a higher resistance change rate and can cope with higher recording density. It is an object of the present invention to provide a method of forming a magnetoresistive effect element that can be formed in a simple manner .

The magnetoresistive element forming method of the present invention includes a magnetization fixed layer having magnetization fixed in a fixed direction, an intervening layer having a base material made of copper, and a magnetization free whose magnetization direction changes according to an external magnetic field. A magnetoresistive effect element including a layer, and a step of forming a magnetization pinned layer using a material containing at least one of cobalt, iron, and nickel; A plurality of metal layers containing manganese and at least one of iridium, platinum, rhodium, and gold, which are less oxidizable than the base material and the magnetic pinned layer, and dispersed in the in-plane direction, and then cover the metal layer As described above, a first base material layer made of a base material, an oxide layer containing an oxide containing manganese and at least one of aluminum, silicon, chromium, titanium, and hafnium, and an oxide layer In It is obtained as a step of preparing an intervening layer by forming a second base layer made of wood in order.

  In the method of forming a magnetoresistive element of the present invention, a metal layer including a base material and a metal that is harder to oxidize than the magnetic pinned layer, a base material layer, and a metal that is more easily oxidized than the base material on the magnetic pinned layer. Since an intervening layer including an oxide layer containing in order is produced, when a sense current is passed in the stacking direction, a current confinement effect that restricts the amount of passage is obtained and exposed to a high temperature environment, for example. Even in this case, the metal layer prevents the metal element constituting the adjacent magnetization pinned layer from entering the inside of the intervening layer.

  In the method for forming a magnetoresistive effect element of the present invention, it is desirable to form the metal layer so as to contain manganese (Mn) together with a metal that is more difficult to oxidize than the base material and the magnetization pinned layer. Moreover, after forming an easily oxidizable metal layer containing a metal that is more easily oxidized than the base material and the magnetization fixed layer on the base material layer, the oxide layer may be formed by oxidizing the metal film. In that case, it is desirable to use, for example, a plasma oxidation method or a natural oxidation method. Copper is used as the base material of the intervening layer, iridium, platinum, rhodium, gold, etc. are used as the metal that is harder to oxidize than the base material and the magnetic pinned layer. Aluminum, silicon, chromium, titanium, hafnium, or the like may be used.

According to the method for forming a magnetoresistive effect element of the present invention, a metal layer containing manganese and a metal that is harder to oxidize than the base material and the magnetization pinned layer is formed on the magnetization pinned layer, and then the metal layer is covered. In this manner, the intervening layer is formed by sequentially forming the first base material layer, the oxide layer containing manganese and manganese that are more easily oxidized than the base material and the magnetization fixed layer , and the second base material layer. As a result, it is possible to obtain a magnetoresistive element that is less likely to deteriorate the purity of the base material due to diffusion of a metal element constituting the adjacent magnetization pinned layer and that exhibits a higher rate of change in resistance. That is, higher sensitivity can be stably obtained over time, and a magnetoresistive effect element suitable for further higher recording density can be realized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  First, referring to FIG. 1 to FIG. 5, the configurations of a magnetoresistive effect element according to an embodiment of the present invention, and a thin film magnetic head, a head gimbal assembly, a head arm assembly, and a magnetic disk device having the same are described below. Explained.

FIG. 1 is a perspective view showing the internal configuration of the magnetic disk apparatus according to the present embodiment. As shown in FIG. 1, the magnetic disk device includes, for example, a magnetic recording medium 200 as a magnetic recording medium on which information is recorded, and information stored in the magnetic recording medium 200. A head arm assembly (HAA) 300 for recording and reproducing the information is provided. The HAA 300 includes a head gimbal assembly (HGA) 2, an arm 3 that supports the base of the HGA 2, and a drive unit 4 as a power source that rotates the arm 3. The HGA 2 includes a magnetic head slider (hereinafter simply referred to as “slider”) 2A having a thin film magnetic head 1 (described later) according to the present embodiment provided on one side surface, and a suspension having the slider 2A attached to one end. 2B. The other end of the suspension 2B (the end opposite to the slider 2A) is supported by the arm 3. The arm 3 is configured to be rotatable via a bearing 6 with a fixed shaft 5 fixed to the housing 100 as a central axis. The drive part 4 consists of a voice coil motor etc., for example. In general, the magnetic disk apparatus includes a plurality of magnetic recording media 200 as shown in FIG. 1, and sliders 2A are provided corresponding to the recording surfaces (front and back surfaces) of each magnetic recording medium 200, respectively. It has come to be. Each slider 2A can move in a direction (X direction) across the reproduction track in a plane parallel to the recording surface of each magnetic recording medium 200. On the other hand, the magnetic recording medium 200 rotates about a spindle motor 7 fixed to the housing 100 in a direction substantially orthogonal to the X direction. Information is recorded on the magnetic recording medium 200 by the rotation of the magnetic recording medium 200 and the movement of the slider 2A, or the recorded information is read out.

FIG. 2 shows the configuration of the slider 2A shown in FIG. The slider 2A has a block-shaped base 8 made of, for example, Altic (Al ₂ O ₃ · TiC). The base 8 is formed in, for example, a substantially hexahedron shape, and is disposed so that one surface thereof is close to and faces the recording surface of the magnetic recording medium 200. A surface facing the recording surface of the magnetic recording medium 200 is a recording medium facing surface (also referred to as an air bearing surface) 9, and air generated between the recording surface and the recording medium facing surface 9 when the magnetic recording medium 200 rotates. Due to the lift caused by the flow, the slider 2 </ b> A floats from the recording surface along the direction facing the recording surface (Y direction) so that a certain gap is formed between the recording medium facing surface 9 and the magnetic recording medium 200. It has become. A thin film magnetic head 1 is provided on one side of the substrate 8 with respect to the recording medium facing surface 9.

  FIG. 3 is an exploded perspective view showing the configuration of the thin film magnetic head 1. FIG. 4 is a cross-sectional view illustrating the structure in the direction of the arrows along the line IV-IV shown in FIG. As shown in FIGS. 3 and 4, the thin film magnetic head 1 includes a reproducing head unit 1 </ b> A for reproducing magnetic information recorded on the magnetic recording medium 200, and a recording for recording magnetic information on a recording track of the magnetic recording medium 200. The head portion 1B is integrally formed.

As shown in FIGS. 3 and 4, the reproducing head portion 1A includes a magnetoresistive effect element having a CPP (Current Perpendicular to the Plane) -GMR (Giant Magnetoresistive) structure in which a sense current flows in the stacking direction. (Hereinafter referred to as MR element) 10. Specifically, on the surface exposed to the recording medium facing surface 9, for example, the lower electrode 11, the MR film 20 and the pair of magnetic domain control films 12, the insulating film 13, and the upper electrode 14 are formed on the substrate 8. The structure is laminated in order. Although not shown in FIGS. 3 and 4, as will be described later, a pair of insulating films is provided between the pair of magnetic domain control films 12 and the MR film 20 and between the pair of magnetic domain control films 12 and the lower electrode 11. 15 is provided. The insulating film 13 is provided so as to surround the periphery of the MR film 20 excluding the recording medium facing surface 9 in the XY plane. Specifically, the insulating film 13 faces the MR film 20 across the X direction. It consists of two parts: a part 13A (see FIG. 3) and a second part 13B (see FIG. 4) occupying a region opposite to the recording medium facing surface 9 with the MR film 20 in between. For example, the lower electrode 11 and the upper electrode 14 each have a thickness of 1 μm to 3 μm and are made of a magnetic metal material such as nickel iron alloy (NiFe). The lower electrode 11 and the upper electrode 14 face each other with the MR film 20 sandwiched in the stacking direction (Z direction), and function so that the MR film 20 is not affected by an unnecessary magnetic field. Further, the lower electrode 11 is connected to the pad 11P, and the upper electrode 14 is connected to the pad 14P, and also has a function as a current path through which current flows in the stacking direction (Z direction) with respect to the MR film 20. . The MR film 20 has a spin valve (SV) structure in which a number of metal films containing a magnetic material are stacked, and has a function of reading magnetic information recorded on the magnetic recording medium 200. The pair of magnetic domain control films 12 are disposed so as to face each other with the MR film 20 interposed therebetween in a direction (X direction) corresponding to the reproduction track width direction of the magnetic recording medium 200. In the reproducing head unit 1A having such a configuration, recorded information is read by utilizing the fact that the electrical resistance of the MR film 20 changes according to the signal magnetic field from the magnetic recording medium 200. The detailed configuration of the MR film 20 will be described later. The insulating film 13 and the insulating layer 16 each have a thickness of 10 nm to 100 nm, for example, and are made of an insulating material such as aluminum oxide (Al ₂ O ₃ ) or aluminum nitride (AlN). The insulating film 13 is mainly for electrically insulating the lower electrode 11 and the upper electrode 14, and the insulating layer 16 is for electrically insulating the reproducing head portion 1A and the recording head portion 1B. It is.

  Next, the configuration of the recording head unit 1B will be described. As shown in FIGS. 3 and 4, the recording head portion 1B is formed on the insulating layer 16 of the reproducing head portion 1A, and includes a lower magnetic pole 41, a recording gap layer 42, a pole tip 43, a coil 44, It has an insulating layer 45, a connecting portion 46 and an upper magnetic pole 47.

The lower magnetic pole 41 is made of a magnetic material such as NiFe and is formed on the insulating layer 16. The recording gap layer 42 is made of an insulating material such as Al ₂ O ₃ and is formed on the lower magnetic pole 41. The recording gap layer 42 has an opening 42A for forming a magnetic path at a position corresponding to the center of the coil 44 in the XY plane. On the recording gap layer 42, a pole tip 43, an insulating layer 45, and a connecting portion 46 are formed in the same plane in this order from the recording medium facing surface 9 side. A coil 44 is embedded in the insulating layer 45. The coil 44 is formed on the recording gap layer 42 with the opening 42A as the center, and is made of, for example, copper (Cu) or gold (Au). Both terminals of the coil 44 are connected to the electrodes 44S and 44E, respectively. The upper magnetic pole 47 is made of, for example, a magnetic material such as NiFe, and is formed on the recording gap layer 42, the pole tip 43, the insulating layer 45, and the connecting portion 46 (see FIG. 4). The upper magnetic pole 47 is in contact with the lower magnetic pole 41 through the opening 42A and is magnetically coupled. Although not shown, an overcoat layer made of Al ₂ O ₃ or the like is formed so as to cover the entire top surface of the recording head portion 1B.

  The recording head unit 1B having such a configuration generates a magnetic flux inside a magnetic path mainly constituted by the lower magnetic pole 41 and the upper magnetic pole 47 by a current flowing through the coil 44, and a signal generated in the vicinity of the recording gap layer 42. Information is recorded by magnetizing the magnetic recording medium 200 with a magnetic field.

  Next, a detailed configuration of the MR element 10 in the thin film magnetic head 1 of the present embodiment will be described with reference to FIG. 5 is a cross-sectional view showing the structure of the MR element 10 as viewed from the direction of the arrow V in FIG.

  As shown in FIG. 5, the MR element 10 includes, in order from the lower magnetic pole 11 side, an underlayer 21, an antiferromagnetic layer 22, a magnetization pinned layer 23, an intervening layer 24, a magnetization free layer 25, The MR film 20 is laminated with the protective layer 26. The underlayer (also referred to as a buffer layer) 21 has a structure in which, for example, a tantalum (Ta) layer having a thickness of 1 nm to 3 nm and a ruthenium (Ru) layer having a thickness of 1 nm to 3 nm are stacked. The antiferromagnetic layer 22 and the magnetization pinned layer 23 (more precisely, the second magnetization pinned film 233 described later) function so as to be favorably exchange-coupled. The antiferromagnetic layer 22 is made of a material exhibiting antiferromagnetism, such as platinum manganese alloy (PtMn) or iridium manganese alloy (IrMn), and has a thickness of 4 nm to 20 nm, for example. The antiferromagnetic layer 22 functions as a so-called pinning layer that fixes the magnetization direction of the magnetization pinned layer 23.

  The magnetization pinned layer 23 has a three-layer structure called a so-called synthetic structure, and the first magnetization pinned film 231 in order from the side far from the antiferromagnetic layer 22 (that is, from the side close to the magnetization free layer 25), A nonmagnetic film 232 and a second magnetization pinned film 233 are provided. The first magnetization fixed film 231 shows the magnetization J231 fixed in a fixed direction, and has a thickness of 2 nm to 4 nm, for example. The nonmagnetic film 232 is made of a nonmagnetic metal material such as copper, ruthenium, rhodium (Rh), or iridium (Ir), and has a thickness of, for example, 0.8 nm. Further, the second magnetization fixed film 233 shows the magnetization J233 fixed in the direction opposite to the magnetization J231, and has a thickness of 2 nm to 4 nm, for example. The first and second magnetization pinned films 231 and 233 form antiferromagnetic exchange coupling via the nonmagnetic film 232, and the directions of their magnetization J231 and J233 are pinned by the antiferromagnetic layer 22. Has been.

The first magnetization pinned film 231 is formed using a ferromagnetic material including, for example, iron (Fe), cobalt (Co), nickel (Ni), etc. as a base material, and has either a single layer structure or a multilayer structure. There may be. For example, a single layer made of CoFe or a structure in which CoFe and copper are alternately and repeatedly stacked may be used. As will be described later, since a magnetoresistive effect can be expected even at the interface between the magnetic material and the nonmagnetic material, the amount of resistance change due to the magnetoresistive effect is improved by forming a multilayer structure such as “CoFe / Cu” as described above. There is expected. The first magnetization pinned film 231 may include a Heusler alloy. Here, the Heusler alloy has an L ₂₁ structure or a B ₂ structure represented by a composition formula of X ₂ YZ (where X and Y are transition metal elements and Z is a semiconductor or a nonmagnetic metal). Or having a C1 ₂ structure whose composition formula is represented by X ₂ YZ. For example, iron, cobalt, nickel, copper, zinc (Zn) or the like is used as X, manganese (Mn), chromium (Cr) or the like is used as Y, and aluminum, silicon, gallium (Ga) is used as Z. , Germanium (Ge), indium (In), tin (Sn), thallium (Tl), lead (Pb), antimony (Sb), and the like are used.

  The second magnetization pinned film 233 is made of a ferromagnetic material containing, for example, at least one of iron, cobalt, and nickel as a base material. Furthermore, the second magnetization pinned film 233 may contain, for example, tantalum (Ta), chromium, vanadium (V), and the like as additive substances.

  The second magnetization pinned film 233 may also have a single layer structure or a laminated structure, like the first magnetization pinned layer 231. For example, it may be a single layer made of components such as cobalt iron tantalum alloy (CoFeTa), cobalt iron nickel chromium alloy (CoFeNiCr), cobalt iron chromium alloy (CoFeCr) or cobalt iron vanadium alloy (CoFeV), or CoFe, Ta A single layer composed of different components such as NiCr, FeCr or FeV may have a laminated structure (for example, “CoFe / Ta”, “CoFe / FeCr”, “CoFe / FeV”, etc.).

  The intervening layer 24 is based on a nonmagnetic metal material having high electrical conductivity (low electrical resistance), and has a thickness of 2 nm to 4 nm, preferably 3.0 nm, for example. The intervening layer 24 mainly disconnects the magnetic coupling between the magnetization free layer 25 and the magnetization pinned layer 23 (first magnetization pinned film 231), and also senses a sense current flowing in the stacking direction (Z direction) during the read operation. It functions to constrict. For example, the sense current passes from the lower electrode 11 through the first magnetization pinned film 231 and then passes through the intervening layer 24 to reach the magnetization free layer 25.

  FIG. 6 shows an enlarged cross-sectional configuration of the intervening layer 24 in the MR film 20 shown in FIG. As shown in FIG. 6, the intervening layer 24 includes a plurality of metal layers 241 that are dispersed in at least the in-plane direction on the upper surface of the magnetization fixed layer 23, and a first base material layer that covers the metal layer 241. 242A, a plurality of oxide layers 243 provided on the upper surface of the first base material layer 242A at least in the in-plane direction, and a second base material layer 242B covering the oxide layer 243. is doing. Here, the first and second base material layers 242A and 242B are both made of a base material such as copper. The metal layer 241 is a metal that is more difficult to oxidize than the constituent materials of the base material and the magnetization fixed layer 23 (that is, a metal having a standard electrode potential larger than that of the base material), specifically, iridium (Ir), platinum (Pt ), Rhodium (Rh) and gold (Au). The oxide layer 243 is non-conductive and is more easily oxidized than the constituent materials of the base material and the magnetization pinned layer 23 (that is, a metal having a standard electrode potential smaller than that of the base material), specifically aluminum ( It is made of an oxide such as Al), silicon (Si), chromium (Cr), titanium (Ti), and hafnium (Hf). The oxide layer 243 may contain manganese.

  The magnetization free layer 25 has a magnetization direction that changes in response to an external magnetic field, and is formed on the opposite side of the second magnetization pinned film 233 with the first magnetization pinned film 231 interposed therebetween. The magnetization free layer 25 has, for example, a two-layer structure of a first ferromagnetic film 251 made of nickel iron alloy (NiFe) and a second ferromagnetic film 252 made of cobalt iron alloy (CoFe). The thickness of the first ferromagnetic film 251 is desirably 2 nm to 6 nm, for example, and the thickness of the second ferromagnetic film 252 is desirably 0.5 nm to 2.5 nm, for example. In the magnetization free layer 25, the magnetizations of the first and second ferromagnetic films 251 and 252 change according to the direction and magnitude of an external magnetic field (in this embodiment, a signal magnetic field from the magnetic recording medium 200). It becomes. The magnetization free layer 25 may be a single layer made of a ferromagnetic material such as CoFe or NiFe. Further, the magnetization free layer 25 may include a Heusler alloy.

  The protective layer 26 has a thickness of, for example, 5 nm to 15 nm and is made of copper, tantalum, ruthenium, or the like, and functions to protect the MR element 10 after film formation in the manufacturing process.

The magnetic domain control film 12 is composed of a base layer 121 formed on the lower electrode 11 via an insulating film 15 and a magnetic domain control layer 122 formed thereon. The magnetic domain control film 12 is disposed so as to face the MR film 20 in the X direction (direction corresponding to the reproduction track width), and applies a longitudinal bias magnetic field to the magnetization free layer 25. More specifically, the underlayer 121 is made of, for example, chromium titanium alloy (CrTi) or tantalum, and functions to improve the growth of the magnetic domain control layer 122 in the manufacturing process. The magnetic domain control layer 122 is made of, for example, cobalt platinum alloy (CoPt) or the like, and functions to promote the formation of a single magnetic domain in the magnetization free layer 25 and suppress the generation of Barkhausen noise. Here, a pair of insulating films 15 are provided between the pair of magnetic domain control films 12 and the MR film 20 and between the pair of magnetic domain control films 12 and the lower magnetic pole 11. The pair of insulating films 15 is made of, for example, a material having electrical insulation properties such as Al ₂ O ₃ or AlN, and is formed so as to continuously cover from both end surfaces S20 of the MR film 20 to the upper surface S11 of the lower magnetic pole 11. Yes. Therefore, the pair of magnetic domain control films 12, the MR film 20, and the lower magnetic pole 11 are electrically insulated.

  As shown in FIG. 5, the lower and upper electrodes 11 and 14 are arranged to face each other so as to sandwich the MR film 20 having the above configuration in a direction (Z direction) perpendicular to the laminated surface. When reading the magnetic information of the medium 200, it functions as a current path for flowing a sense current in the Z direction with respect to the MR film 20.

  Next, the reproducing operation of the MR element 10 and the thin film magnetic head 1 configured as described above will be described with reference to FIGS.

  In the thin film magnetic head 1, information recorded on the magnetic recording medium 200 is read by the reproducing head unit 1A. When reading recorded information, the recording medium facing surface 9 faces the recording surface of the magnetic recording medium 200, and in this state, the signal magnetic field from the magnetic recording medium 200 reaches the MR element 10. At this time, a sense current is passed through the MR film 20 in advance in the stacking direction (Z direction) via the lower electrode 11 and the upper electrode 14. That is, a sense current is passed through the MR film 20 in the order of the underlayer 21, the antiferromagnetic layer 22, the magnetization pinned layer 23, the intervening layer 24, the magnetization free layer 25, and the protective layer 26, or vice versa. ing. In the MR film 20, a magnetization free layer 25 whose magnetization direction is changed by a signal magnetic field and a magnetization fixed layer 23 whose magnetization direction is fixed to a substantially constant direction by the antiferromagnetic layer 22 and not affected by the signal magnetic field. Thus, the relative magnetization direction changes. As a result, a change in spin-dependent scattering of conduction electrons occurs, and a change occurs in the electrical resistance of the MR film 20. This change in electrical resistance causes a change in output voltage, and the recording information of the magnetic recording medium 200 is read by detecting this change in current. Further, by providing the pair of insulating films 15, the sense current flowing between the lower shield 11 and the upper shield 14 is less likely to leak into the pair of magnetic domain control films 12. That is, since the sense current passes through the MR film 20 without being spread in the X direction, the resistance change of the sense current due to the change in the magnetization direction of the magnetization free layer 25 is detected with higher sensitivity. can do.

  Further, the intervening layer 24 has an oxide layer 243 embedded in the conductive first and second base material layers 242A and 242B, and this oxide layer 243 serves as a so-called current confinement (CCP) layer. Since the function is exhibited and a current confinement effect that restricts the passage amount of the sense current flowing in the stacking direction (Z direction) is brought about, the resistance change rate is improved. On the other hand, since the metal layer 241 made of a metal that is harder to oxidize than the constituent material of the substrate and the magnetization pinned layer 23 is provided at the interface between the intervening layer 24 and the first magnetization pinned film 231, for example, in a high temperature environment Even if the metal layer 241 is exposed to the metal layer 241, the metal element constituting the magnetization pinned layer 23 is prevented from entering the inside of the intervening layer 24. By such an action, the resistance change rate can be improved while suppressing the deterioration of the purity of the base material due to the diffusion of different metals. As a result, the magnetic disk device including the thin film magnetic head 1 having the MR element 10 can stably exhibit higher sensitivity over time. Therefore, it can be said that it is suitable for further higher recording density.

  Next, a method for manufacturing the thin film magnetic head 1 will be described with reference to FIGS. Here, the part which mainly forms MR element 10 is demonstrated in detail.

  In the method of manufacturing the thin film magnetic head according to the present embodiment, the step of forming the lower electrode 11 on the substrate 8 and the antiferromagnetic layer 22 and the magnetization fixed layer on the lower electrode 11 from the lower electrode 11 side are provided. A step of forming a multilayer film 20Z including a structure in which an intermediate layer 23, an intervening layer 24, and a magnetization free layer 25 are disposed in order, and a region corresponding to a portion defining the element width is protected on the multilayer film 20Z. The step of selectively forming the photoresist pattern 61, the step of forming the MR element 10 by selectively etching the multilayer film 20Z using the photoresist pattern 61 as a mask, After selectively forming the magnetic film, the step of forming the pair of magnetic domain control films 12 via the insulating film 15 by removing the photoresist pattern 61 and the pair of magnetic domain control films 1 Forming an insulating film 13 on the, after removing the photoresist pattern 61, it is intended to include forming an upper electrode 14 over the entire surface. Hereinafter, each step will be described in detail.

  First, as shown in FIG. 7, a multilayer film 20Z is formed over the entire surface of the lower electrode 11 formed on one side surface of the substrate 8. Specifically, the underlayer 21, the antiferromagnetic layer 22, the magnetization pinned layer 23, the intervening layer 24, the magnetization free layer 25, and the protective layer 26 are sequentially stacked by sputtering or the like. This multilayer film 20Z will become the MR film 20 later. In FIGS. 7 and 10 to 13, illustration of the internal structure of the MR film 20 and the multilayer film 20 </ b> Z in the formation process thereof is omitted, but both correspond to the MR film 20 shown in FIG. 5 described above. Has an internal structure.

  Here, with reference to FIG. 8 and FIG. 9, the formation process of the intervening layer 24 is demonstrated in detail.

  First, as shown in FIG. 8, iridium, platinum, rhodium, which is a metal that is harder to oxidize than copper and the constituent material of the magnetization pinned layer 23, on the magnetization pinned layer 23 (first magnetization pinned film 231). An alloy layer 241Z made of an alloy containing at least one kind of gold and manganese is formed so as to have a thickness of 0.1 nm to 1.0 nm, for example. In FIG. 8 and the like, the alloy layer 241Z is formed discontinuously in the in-plane direction, but it is desirable to use a continuous layer if possible. In practice, however, such a thickness is generally discontinuous. After forming the alloy layer 241Z, aluminum, silicon, chromium, titanium, which is a metal that is easier to oxidize than the constituent material of the first base material layer 242A made of copper or the like and copper and the magnetization pinned layer 23 so as to cover the alloy layer 241Z And an easily oxidizable metal layer 243Z made of hafnium or the like is formed in order. About 1st base material layer 242A, it forms so that it may become thickness of about 1.0 nm-1.5 nm, for example. On the other hand, the easily oxidizable metal layer 243Z is formed to have a thickness of, for example, about 0.1 nm to 0.4 nm so as to be a discontinuous layer.

  After that, the oxide layer 243 (FIG. 9) is formed by oxidizing the oxidizable metal layer 243Z using a plasma oxidation method or a natural oxidation method. At this time, not only the easily oxidizable metal layer 243Z but also the first base material layer 242A and the alloy layer 241Z which are lower layers thereof are affected by oxygen gas and oxygen plasma. However, since manganese contained in the alloy layer 241Z moves to the oxidizable metal layer 243Z and forms an oxide together with the metal (aluminum, silicon, chromium, titanium, hafnium, etc.) constituting the original oxidizable metal layer 243Z, The first base material layer 242A itself can be prevented from being oxidized. After the oxide layer 243 is formed, the second base material layer 242B is formed so as to cover the whole, whereby the intervening layer 24 having the configuration shown in FIG. 6 is completed. Note that the alloy layer 241Z, the first base material layer 242A, the easily oxidizable metal layer 243Z, and the second base material layer 242B are all preferably formed by a sputtering method.

  Subsequently, as shown in FIG. 10, a photoresist pattern 61 is selectively formed on the multilayer film 20Z so as to have a width W corresponding to a portion defining the element width. In this case, the end portion of the photoresist pattern 61 may be partially removed using a predetermined solvent to form an undercut.

  Next, the multilayer film 20Z is selectively removed using dry etching such as ion milling or RIE using the photoresist pattern 61 as a mask. In this case, dry etching is performed until the lower electrode 11 is reached. As a result, as shown in FIG. 11, the MR film 20 having the width Tw is formed. This width Tw is an average element width of the MR film 20. After the MR film 20 is formed, as shown in FIG. 12, a pair of insulating films 15 and a pair of magnetic domain control films 12 are formed so as to be adjacent to both sides of the MR film 20 in the X direction. Specifically, for example, the insulating film 15, the base layer 121, and the magnetic domain control layer 122 are sequentially formed over the entire surface by sputtering or the like. Further, an insulating film 13 is formed on the magnetic domain control film 12 by sputtering. Next, the photoresist pattern 61 is lifted off, so that the MR film 20, a pair of insulating films 15 that are opposed to each other, and a pair of magnetic domain control films 12 including a base layer 121 and a magnetic domain control layer 122 appear.

  After removing the photoresist pattern 61, the upper electrode 14 is formed over the entire surface as shown in FIG. Thereby, the MR element 10 is completed once. Thereafter, as shown in FIGS. 3 and 4, the insulating layer 16 is formed over the entire surface, thereby completing the reproducing head portion 1A. Subsequently, the lower magnetic pole 41 and the recording gap layer 42 are sequentially formed on the reproducing head portion 1A, and the coil 44 is selectively formed on the recording gap layer 42. Thereafter, a part of the recording gap layer 42 is etched to form an opening 42A. Next, an insulating layer 45 is formed so as to cover the coil 44, and a pole tip 43 and a connecting portion 46 are sequentially formed. Finally, the upper magnetic pole 47 is formed so as to cover the whole, thereby completing the recording head portion 1B. Thereafter, the thin film magnetic head 1 is completed through a predetermined process such as machining the slider 2A to form the recording medium facing surface 2F.

  As described above, in the present embodiment, the alloy layer 241Z containing manganese and a metal that is harder to oxidize than the constituent material of the base material (for example, copper) and the magnetization pinned layer 23 on the first pinned film 231; Since the first base material layer 242A and the easily oxidizable metal layer 243Z are formed in this order and then the oxidation treatment is performed, the oxide layer 243 is formed while preventing the first base material layer 242A from being oxidized. can do. On the other hand, since the metal layer 241 remains on the surface of the first magnetization pinned film 231, the metal element constituting the magnetization pinned layer 23 enters the first and second base material layers 242A and 242B as impurities. Can be suppressed. As a result, the purity of the base material constituting the first and second base material layers 242A and 242B is not lowered, and a CCP structure that exhibits a good current confinement effect is obtained. Therefore, it is possible to realize an MR element that can stably exhibit good sensitivity.

  In particular, when the first magnetization pinned film 231 is formed using a Heusler alloy containing manganese, the presence of the metal layer 241 is effective in suppressing a decrease in magnetoresistance effect rate. This is because, when manganese as a metal enters the intervening layer 24, a negative effect of canceling spin information of spin electrons included in the sense current is exhibited. In addition, it is thought that manganese does not show such a negative effect when constituting an oxide.

  Next, specific examples of the present invention will be described.

In the examples of the present invention described below, samples of the MR element 10 including the MR film 20 having the cross-sectional structure shown in FIGS. 5 and 6 are manufactured based on the manufacturing method described in the above embodiment. The characteristics of this sample were investigated. Hereinafter, each example will be described with reference to Tables 1 to 5. In each example, the formation area of the MR film 20 was 0.04 μm ² (0.2 μm × 0.2 μm).

(Examples 1-1 to 1-7)
Here, the MR film 20 was fabricated so as to have the configuration shown in Table 1 below. However, as shown in Table 2 (described later), an alloy layer having a thickness of 0.03 nm to 1.00 nm was produced using IrMn in the production stage, and finally a metal layer made of iridium (Ir) was formed. I tried to get it. In forming the oxide layer, an easily oxidizable metal layer is formed using aluminum, and plasma is formed by plasma oxidation using argon (Ar) gas and oxygen gas (O ₂ ). The oxidizable metal layer was oxidized for 60 seconds at an input power of 30 watts (W) or less. Further, the contents of aluminum and manganese in the oxide layer were changed as shown in Table 2 by changing the thickness of the alloy layer. Here, the content means the weight of aluminum with respect to the total weight of aluminum and manganese [Al / (Al + Mn)], or the weight of manganese with respect to the total weight of aluminum and manganese [Mn / (Al + Mn)]. About each Example obtained in this way, resistance change rate (%) and sheet resistance (ohm * micrometer < ² >) were measured. The results are shown in Table 2.

  In addition, as Comparative Example 1-1 with respect to Examples 1-1 to 1-7, MR elements having the same configuration except that the metal layer in the intervening layer was not provided were manufactured, and the same investigation was performed. The results are also shown in Table 2.

  As shown in Table 2, in Examples 1-1 to 1-7, it is possible to obtain a higher resistance change rate than Comparative Example 1-1 while maintaining a sheet resistance substantially equivalent to that of Comparative Example 1-1. did it. In particular, an alloy layer made of IrMn is formed with a thickness of 0.1 nm to 8.0 nm and the manganese content in the oxide layer is changed from 19.4% to 63.1%, thereby improving the resistance change rate. It turns out to be more effective. Such a result shows that during the oxidation treatment, manganese moves from IrMn constituting the alloy layer to the easily oxidizable metal layer, and forms AlMnOx together with aluminum, thereby oxidizing the copper constituting the first base material layer. It is presumed that the effect of preventing was manifested. At the same time, it is considered that iridium as a metal layer remaining on the surface of the first magnetization pinned film 231 has an effect of suppressing the oxidation of the first magnetization pinned film 231. In Example 1-7, since the thickness of the alloy layer is large, manganese contained in the alloy layer is not sufficiently oxidized and remains in the metal layer, causing a slight decrease in resistance change rate. It is considered a thing.

(Examples 2-1 to 2-6)
Here, except for using PtMn as the alloy layer, the MR element 1 including the MR film 20 having the configuration shown in Table 1 was manufactured in the same manner as in Examples 1-1 to 1-7. In this example, the same evaluation as in Examples 1-1 to 1-7 was performed. The results are as shown in Table 2. Also in the present example, a resistance change rate higher than that of Comparative Example 1-1 could be obtained while maintaining a sheet resistance substantially equivalent to that of Comparative Example 1-1. In particular, an alloy layer made of PtMn is formed with a thickness of 0.3 nm to 1.0 nm and the content of manganese in the oxide layer is changed from 34.3% to 60.7% to improve the resistance change rate. It turns out to be more effective.

(Examples 3-1 and 4-1)
Here, except for using RhMn or AuMn as the alloy layer, the MR element 1 including the MR film 20 having the configuration shown in Table 1 was manufactured in the same manner as in Examples 1-1 to 1-7. In Examples 3-1 and 4-1, evaluations similar to those in Examples 1-1 to 1-7 were performed. The results are as shown in Table 2. Also in this example, it was possible to obtain a higher resistance change rate than Comparative Example 1-1 while maintaining a sheet resistance substantially equivalent to that of Comparative Example 1-1.

(Examples 5-1 and 5-2)
Here, the MR film 20 was fabricated so as to have the configuration shown in Table 3 below. Specifically, the configuration of the first magnetization pinned film 231 is the same as that of Examples 1-1 to 1-7 except that the configuration of the first magnetization pinned film 231 is a three-layer structure including a Heusler alloy as shown in Table 3. Thus, the MR element 1 provided with the MR film 20 was produced. As the Heusler alloy, Co ₂ MnGe (Example 5-1) and Co ₂ MnSi (Example 5-2) were employed. Furthermore, as Comparative Example 5-1 with respect to Examples 5-1 and 5-2, the first magnetization pinned film 231 was a single layer made of FeCo having a thickness of 4 nm, and the metal layer in the intervening layer was not provided. Except for, MR elements having the same configuration as in Examples 5-1 and 5-2 were manufactured. Further, as Comparative Example 5-2 with respect to Example 5-1, an MR element having the same configuration as that of Example 5-1 was manufactured except that the metal layer in the intervening layer was not provided. These Examples 5-1 and 5-2 and Comparative Examples 5-1 and 5-2 were also evaluated in the same manner as in Examples 1-1 to 1-7. The results are shown in Table 4.

  As shown in Table 4, Examples 5-1 and 5-2, when compared with Comparative Example 5-1, developed a higher rate of resistance change while maintaining substantially the same area resistance, When compared with Comparative Example 5-2, it was found that a higher resistance change rate was exhibited while reducing the sheet resistance. Therefore, even when the first magnetization pinned film 231 has a three-layer structure including a Heusler alloy, as in Examples 1-1 to 1-7, during the oxidation treatment, IrMn constituting the alloy layer is changed to manganese. Is transferred to the easily oxidizable metal layer, and by forming AlMnOx together with aluminum, the effect of preventing the oxidation of copper constituting the first base material layer is obtained, and the surface of the first magnetization pinned film 231 is obtained. It is considered that the iridium as the remaining metal layer also has an effect of suppressing the oxidation of the first magnetization pinned film 231.

(Examples 6-1 to 6-6)
Here, MR element 1 provided with MR film 20 having the same configuration (Table 1) as Examples 1-1 to 1-7 was manufactured. However, as shown in Table 5, the time for performing the oxidation treatment was changed in the range of 30 seconds to 300 seconds. In this example, the same evaluation as in Examples 1-1 to 1-7 was performed, and the results are shown in Table 5. Further, as Comparative Examples 6-1 to 6-6 for this example, MR elements were similarly manufactured except that the alloy layer was not provided, and the same investigation was performed. It was. Further, Table 5 shows a comparative example 6-7 in which the same investigation was performed on the MR element manufactured without performing the oxidation treatment after preparing the alloy layer made of IrMn.

  As shown in Table 5, when Examples 6-1 to 6-6 and Comparative Examples 6-1 to 6-6 were respectively compared, in each Example, the oxidation treatment time was up to 60 seconds. Almost the same area resistance was exhibited, and when the oxidation treatment time was longer than that, the area resistance was smaller than in each comparative example. Furthermore, in each Example, the resistance change rate higher than each comparative example was able to be obtained. This is because in each comparative example in which no alloy layer was provided, the resistance change rate decreased and the sheet resistance increased because the first magnetization pinned film and the like were affected by oxygen plasma during the oxidation process. Probably because. In Comparative Example 6-7, although an alloy layer made of IrMn was provided, the oxidation treatment was not performed, so that manganese remained in the metal layer in a metal state, resulting in a decrease in resistance change rate. It seems to have resulted.

(Examples 7-1 to 7-4)
Here, in the production stage, instead of an alloy layer such as IrMn, iridium (Example 7-1), platinum (Example 7-2), rhodium (Example 7-3) or gold (Example), which is a single metal, is used. 7-4), except that the metal layer 241 is formed on the magnetization pinned layer 23, and the configuration shown in Table 6 below is the same as in Examples 1-1 to 1-7. The MR element 1 provided with the MR film 20 was prepared. The thickness of each metal layer 241 was 0.5 nm. These Examples 7-1 to 7-4 were also evaluated in the same manner as in Examples 1-1 to 1-7. The results are shown in Table 7 together with Comparative Example 1-1.

  As shown in Table 7, in Examples 7-1 to 7-4, it is possible to obtain a resistance change rate higher than that of Comparative Example 1-1 while maintaining approximately the same area resistance as that of Comparative Example 1-1. did it. As a result, it was confirmed that iridium, platinum, rhodium and gold as the metal layer provided on the surface of the first magnetization pinned film 231 exhibited an effect of suppressing the oxidation of the first magnetization pinned film 231. .

  Although the present invention has been described with reference to the embodiments and some examples, the present invention is not limited to these embodiments and examples and can be variously modified. For example, in the present embodiment and examples, the MR element having the bottom type synthetic spin valve structure has been described as an example, but the present invention is not limited to this, and the top type may be used. In the present embodiment and example, a single spin valve MR element having one synthetic magnetization pinned layer has been described as an example. However, the present invention is not limited to this, and the synthetic magnetization pinned layer is not limited to this. It is also possible to provide a dual spin valve type MR element having two. In this case, an intervening layer is provided above and below the magnetization free layer. The above-described intervening layer is formed according to the configuration of the present invention, or by producing the intervening layer by the manufacturing method of the present invention, the above-mentioned. The effects of the present invention can be obtained.

  In the above embodiment, the insulating film 13A is provided on the magnetic domain control film 12, but the insulating film 13A may be omitted.

It is a perspective view showing the structure of the actuator arm provided with the thin film magnetic head which concerns on one embodiment of this invention. It is a perspective view showing the structure of the slider in the actuator arm shown in FIG. 1 is an exploded perspective view showing a configuration of a thin film magnetic head according to an embodiment of the invention. It is sectional drawing showing the structure of the arrow direction along the IV-IV line of the thin film magnetic head shown in FIG. FIG. 5 is a cross-sectional view illustrating a configuration of a main part when viewed from the direction of arrow V of the thin film magnetic head illustrated in FIG. 4. FIG. 6 is an enlarged cross-sectional view showing a main part of the MR element shown in FIG. 5 in an enlarged manner. FIG. 3 is a cross-sectional view of a principal part showing one step in the method of manufacturing the thin film magnetic head shown in FIG. 1. FIG. 8 is an enlarged cross-sectional view of a main part for explaining details of one step in the method of manufacturing the thin film magnetic head shown in FIG. 7. It is principal part sectional drawing showing the 1 process following FIG. It is principal part sectional drawing showing the 1 process following FIG. It is principal part sectional drawing showing the 1 process following FIG. FIG. 12 is an essential part cross-sectional view illustrating a process following FIG. 11. It is principal part sectional drawing showing the 1 process following FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Thin film magnetic head, 2 ... Head gimbal assembly (HGA), 2A ... Slider, 2B ... Suspension, 3 ... Arm, 4 ... Drive part, 5 ... Fixed shaft, 6 ... Bearing, 7 ... Spindle motor, 8 ... Base | substrate, DESCRIPTION OF SYMBOLS 9 ... Recording medium opposing surface, 10 ... Magnetoresistive effect (MR) element, 11 ... Lower electrode, 12 ... Magnetic domain control film, 13, 15 ... Insulating film, 14 ... Upper electrode, 16 ... Insulating layer, 20 ... MR film, DESCRIPTION OF SYMBOLS 21 ... Underlayer, 22 ... Antiferromagnetic layer, 23 ... Magnetization fixed layer, 231 ... 1st magnetization fixed film, 232 ... Nonmagnetic film, 233 ... 2nd magnetization fixed film, 24 ... Intervening layer, 241 ... Metal Layer, 241Z ... alloy layer, 242A ... first substrate layer, 242B ... second substrate layer, 243 ... oxide layer, 243Z ... easily oxidizable metal layer, 25 ... magnetization free layer, 26 ... protective layer, 41 ... bottom pole, 42 ... recording gap layer, 43 ... Ruchippu, 44 ... coil, 45 ... insulating layer, 46 ... connecting unit, 47 ... upper pole, 100 ... housing, 200 ... magnetic recording medium, 300 ... head arm assembly (HAA).

Claims (4)

Magnetoresistive effect comprising a magnetization pinned layer having magnetization pinned in a fixed direction, an intervening layer having a base material made of copper (Cu), and a magnetization free layer whose magnetization direction changes in response to an external magnetic field A method of forming an element, comprising:
Forming the magnetization pinned layer using a material containing at least one of cobalt (Co), iron (Fe), and nickel (Ni);
On the magnetization pinned layer, at least one of iridium (Ir), platinum (Pt), rhodium (Rh) and gold (Au), which is less oxidized than the base material and the magnetization pinned layer, and manganese (Mn) A first base material layer made of the base material, aluminum (Al), silicon (Si), and so as to cover the metal layer. An oxide layer containing an oxide containing at least one of chromium (Cr), titanium (Ti), and hafnium (Hf) and manganese and a second base material layer made of the base material are sequentially formed. And a step of forming the intervening layer. A method of forming a magnetoresistive element, comprising: After forming an easily oxidizable metal layer containing at least one of aluminum (Al), silicon (Si), chromium (Cr), titanium (Ti) and hafnium (Hf) on the first base material layer. The method for forming a magnetoresistive element according to claim 1 , wherein the oxide layer is formed by oxidizing the oxidizable metal layer. The method for forming a magnetoresistive element according to claim 2, wherein the oxide layer is formed by oxidizing the easily oxidizable metal layer using a plasma oxidation method or a natural oxidation method. The method of forming a magnetoresistive element according to any one of claims 1 to 3 , wherein the magnetization pinned layer is formed so as to contain manganese.

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