JP4539876B2 - Method for manufacturing magnetoresistive element - Google Patents

Description

  The present invention relates to a method for manufacturing a magnetoresistive effect element in which a current for detecting a magnetic signal is caused to flow in a direction crossing the plane of each layer constituting the magnetoresistive effect element.

  In recent years, with the improvement of the surface recording density of magnetic disk devices, there has been a demand for improved performance of thin film magnetic heads. As a thin film magnetic head, a reproducing head having a magnetoresistive effect element for reading (hereinafter also referred to as MR (Magnetoresistive) element) and a recording head having an inductive electromagnetic transducer for writing are laminated on a substrate. A composite thin film magnetic head having the above structure is widely used.

  MR elements include an AMR element using an anisotropic magnetoresistive effect, a GMR element using a giant magnetoresistive effect, and a TMR element using a tunneling magnetoresistive effect. Etc.

  The characteristics of the reproducing head are required to be high sensitivity and high output. As a reproducing head that satisfies this requirement, GMR heads using spin-valve GMR elements have already been mass-produced. Recently, in order to cope with the further improvement of the surface recording density, development of a reproducing head using a TMR element has been advanced.

  In general, a spin valve type GMR element includes a free layer, a fixed layer, a nonmagnetic conductive layer disposed between them, and an antiferroelectric layer disposed on the opposite side of the fixed layer to the nonmagnetic conductive layer. And a magnetic layer. The free layer is a ferromagnetic layer whose magnetization direction changes according to the signal magnetic field. The fixed layer is a ferromagnetic layer whose magnetization direction is fixed. The antiferromagnetic layer is a layer that fixes the direction of magnetization in the fixed layer by exchange coupling with the fixed layer.

  By the way, the conventional GMR head has a structure in which a current for magnetic signal detection (hereinafter referred to as a sense current) flows in a direction parallel to the surface of each layer constituting the GMR element. Such a structure is called a CIP (Current In Plane) structure. On the other hand, development of a GMR head having a structure in which a sense current flows in a direction intersecting with the surface of each layer constituting the GMR element, for example, in a direction perpendicular to the surface of each layer constituting the GMR element is also in progress. Such a structure is called a CPP (Current Perpendicular to Plane) structure. Hereinafter, the GMR element used for the reproducing head having the CPP structure is called a CPP-GMR element, and the GMR element used for the reproducing head having the CIP structure is called a CIP-GMR element.

  The CPP-GMR element has an advantage that the resistance value is small compared with the TMR element, and therefore high frequency response is good. In addition, the CPP-GMR element has an advantage that a large output can be obtained when the track width is reduced as compared with the CIP-GMR element. On the other hand, since the CPP-GMR element has a small resistance value, it also has a drawback that a resistance change amount is small. Therefore, in order to obtain a large reproduction output using the CPP-GMR element, it is necessary to increase the voltage applied to the element. However, when the voltage applied to the element is increased, the following problems occur. In the CPP-GMR element, a current flows in a direction perpendicular to the surface of each layer. Then, spin-polarized electrons are injected from the free layer to the fixed layer or from the fixed layer to the free layer. The spin-polarized electrons generate a torque that rotates their magnetization in the free layer or the fixed layer. In the present application, this torque is referred to as spin torque. This spin torque is proportional to the current density. When the voltage applied to the CPP-GMR element is increased, the current density is increased, and as a result, the spin torque is increased. When the spin torque is increased, there arises a problem that the magnetization direction of the fixed layer changes.

  Therefore, a current confinement type CPP-GMR element is proposed in which the resistance value and the resistance change amount can be increased as compared with a general CPP-GMR element. This current confinement type CPP-GMR element is, for example, a spacer layer including an insulating part and a conductive part so as to be mixed in a cross section parallel to the surface instead of a nonmagnetic conductive layer in a general CPP-GMR element. It has. In this current confinement type CPP-GMR element, a current flows locally through the conductive portion in the spacer layer, so that a resistance value and a resistance change amount are larger than those of a general CPP-GMR element.

  Patent Document 1 discloses a current confinement type in which a spacer layer including a current control region for limiting the flow rate of a sense current and an insulator region for blocking the flow of the sense current is provided between a fixed layer and a free layer. CPP-GMR elements are described. Patent Document 1 describes a method of forming a spacer layer by locally irradiating a metal film with an ion beam and then oxidizing the metal film.

  Patent Document 2 includes a spacer layer composed of a lower nonmagnetic intermediate layer, a magnetic intermediate layer, an insulating layer, and an upper nonmagnetic intermediate layer arranged in order from the lower side between the fixed layer and the free layer. The current confinement type CPP-GMR element is described. In this CPP-GMR element, the insulating layer is formed with a portion through which electrons easily pass due to extremely fine non-uniformity such as the film quality of the insulating layer. Patent Document 2 describes a method of forming the insulating layer by oxidizing the surface of a magnetic intermediate layer.

  Patent Document 3 describes a current confinement type CPP-GMR element in which a spacer layer provided between a fixed layer and a free layer includes an insulating layer and a current path passing through the insulating layer. ing. In Patent Document 3, a second metal layer is formed on a first metal layer, a pretreatment of irradiating the second metal layer with a rare gas ion beam or RF plasma is performed, and then an oxidizing gas is used. Alternatively, a method is described in which the spacer layer is formed by supplying a nitriding gas to convert the second metal layer into an insulating layer.

JP 2005-136309 A JP 2004-207366 A JP 2006-54257 A

  As described in Patent Documents 1 to 3, in a conventional current confinement type CPP-GMR element, generally, an insulating portion in a spacer layer is formed using an oxidation process. In this case, since the variation in the oxidation state in the insulating portion becomes large, it is difficult to stably form the spacer layer. Therefore, the conventional current confinement type CPP-GMR element has a problem that the variation in characteristics becomes large.

  In addition, in a current confinement type CPP-GMR element having a configuration in which a fixed layer is disposed under a spacer layer, when oxidation treatment is performed at the time of forming the spacer layer, the oxidation treatment causes the interface between the fixed layer and the spacer layer. There is a possibility that a nearby portion is damaged and the magnetization of the portion disappears. The state of magnetization in the portion of the fixed layer in the vicinity of the interface with the spacer layer greatly affects the magnetoresistance change rate (hereinafter referred to as MR ratio), which is the ratio of magnetoresistance change to resistance in the MR element. Therefore, if the magnetization of the portion near the interface with the spacer layer in the fixed layer disappears due to the oxidation treatment, the MR ratio may be lowered.

  In addition, in the current confinement type CPP-GMR element in which the free layer is disposed under the spacer layer, if the oxidation process is performed at the time of forming the spacer layer, the soft magnetic characteristics of the free layer deteriorate due to the oxidation process, As a result, the MR ratio may be reduced.

  The present invention has been made in view of such a problem, and an object thereof is to include an insulating portion and a conductive portion so that the spacer layer is mixed in a cross section parallel to the surface, and a current for detecting a magnetic signal is generated. A method of manufacturing a magnetoresistive effect element that flows in a direction crossing the surface of each layer constituting the magnetoresistive effect element, which can suppress a decrease in the MR ratio of the magnetoresistive effect element, and the characteristics of the magnetoresistive effect element It is an object of the present invention to provide a method of manufacturing a magnetoresistive element capable of reducing the variation of the magnetoresistance effect.

  A magnetoresistive element manufactured by the method of manufacturing a magnetoresistive element of the present invention is disposed between a first magnetic layer, a second magnetic layer, and the first magnetic layer and the second magnetic layer. Spacer layer. One of the first magnetic layer and the second magnetic layer is a layer whose magnetization direction is fixed, and the other of the first magnetic layer and the second magnetic layer has a magnetization direction according to an external magnetic field. It is a changing layer. The spacer layer includes an insulating portion and a conductive portion so as to be mixed in a cross section parallel to the surface. In this magnetoresistive effect element, a current for detecting a magnetic signal is passed in a direction crossing the surface of each layer constituting the magnetoresistive effect element.

  The method of manufacturing a magnetoresistive element of the present invention includes a step of forming a first magnetic layer, a step of forming a spacer layer on the first magnetic layer, and a second magnetic layer on the spacer layer. Forming.

The step of forming the spacer layer includes
Forming a first nonmagnetic metal layer made of a nonmagnetic metal material on the first magnetic layer;
Forming a second nonmagnetic metal layer made of a nonmagnetic metal material on the first nonmagnetic metal layer so as to have an island-like structure or an upper surface having irregularities;
The laminated film composed of the first nonmagnetic metal layer and the second nonmagnetic metal layer is formed such that the second nonmagnetic metal layer is removed and irregularities are formed on the upper surface of the first nonmagnetic metal layer. A first etching step for etching the upper surface;
Forming an insulating layer made of an insulating material on the first nonmagnetic metal layer after the first etching step;
Etching a portion of the insulating layer by wet etching so that the convex portion on the upper surface of the first nonmagnetic metal layer is exposed and the insulating layer remains in the concave portion on the upper surface of the first nonmagnetic metal layer; Etching process.

  In the magnetoresistive effect element manufacturing method of the present invention, the insulating portion is formed by the insulating layer, and the conductive portion is formed by the first nonmagnetic metal layer.

  In the method of manufacturing a magnetoresistive element of the present invention, the nonmagnetic metal material constituting the first nonmagnetic metal layer is Cu, and the nonmagnetic metal material constituting the second nonmagnetic metal layer is Ag. Also good.

  In the method for manufacturing a magnetoresistive element of the present invention, the second nonmagnetic metal layer may be formed by a vacuum evaporation method.

  In the method of manufacturing a magnetoresistive effect element of the present invention, the step of forming the spacer layer may further include a step of forming a spacer layer on the first nonmagnetic metal layer and the insulating layer after the second etching step. A step of forming a third nonmagnetic metal layer made of the material may be included. In this case, the nonmagnetic metal material constituting the third nonmagnetic metal layer may be Cu.

  According to the method of manufacturing a magnetoresistive element of the present invention, a spacer layer including an insulating portion and a conductive portion can be formed without performing an oxidation treatment. Further, according to the method of manufacturing a magnetoresistive effect element of the present invention, the distribution of the insulating portion and the conductor portion is not determined by the oxidation treatment, but is determined by the shape of the second nonmagnetic metal layer. For these reasons, according to the present invention, it is possible to suppress a decrease in the MR ratio of the magnetoresistive effect element and to reduce variations in characteristics of the magnetoresistive effect element.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The magnetoresistive effect element manufacturing method according to the first embodiment of the present invention is applied to, for example, a magnetoresistive effect element included in a reproducing head in a thin film magnetic head.

  First, an example of the configuration of the thin film magnetic head will be described with reference to FIGS. 3 is a cross-sectional view showing a cross section perpendicular to the medium facing surface and the substrate of the thin film magnetic head, and FIG. 4 is a cross sectional view showing a cross section parallel to the medium facing surface of the magnetic pole portion of the thin film magnetic head.

The thin film magnetic head shown in FIGS. 3 and 4 includes a medium facing surface 20 that faces the recording medium. The thin film magnetic head has an insulating substrate 1 made of a ceramic material such as AlTiC (Al ₂ O ₃ .TiC) and an insulating material made of an insulating material such as alumina (Al ₂ O ₃ ) disposed on the substrate 1. A layer 2, a first shield layer 3 made of a magnetic material disposed on the insulating layer 2, an MR element 5 disposed on the first shield layer 3, and 2 of the MR element 5 Two bias magnetic field application layers 6 arranged so as to be adjacent to one side portion, and an insulating layer 7 arranged around the MR element 5 and the bias magnetic field application layer 6 are provided. The MR element 5 is disposed in the vicinity of the medium facing surface 20. The insulating layer 7 is made of an insulating material such as alumina.

  The thin-film magnetic head is further disposed on the second shield layer 8 and the second shield layer 8 made of a magnetic material disposed on the MR element 5, the bias magnetic field applying layer 6 and the insulating layer 7. A separation layer 18 made of a nonmagnetic material such as alumina and a lower magnetic pole layer 19 made of a magnetic material disposed on the separation layer 18 are provided. The magnetic material used for the second shield layer 8 and the bottom pole layer 19 is a soft magnetic material such as NiFe, CoFe, CoFeNi, FeN or the like. Instead of the second shield layer 8, the separation layer 18, and the lower magnetic pole layer 19, a second shield layer that also serves as the lower magnetic pole layer may be provided.

  The thin film magnetic head further includes a recording gap layer 9 made of a nonmagnetic material such as alumina and disposed on the lower magnetic pole layer 19. A contact hole 9 a is formed in the recording gap layer 9 at a position away from the medium facing surface 20.

  The thin film magnetic head further includes a first layer portion 10 of a thin film coil disposed on the recording gap layer 9. The first layer portion 10 is made of a conductive material such as copper (Cu). In FIG. 3, reference numeral 10 a represents a connection portion of the first layer portion 10 that is connected to a second layer portion 15 of a thin film coil to be described later. The first layer portion 10 is wound around the contact hole 9a.

  The thin film magnetic head further includes an insulating layer 11 made of an insulating material arranged to cover the first layer portion 10 of the thin film coil and the recording gap layer 9 therearound, an upper magnetic pole layer 12 made of a magnetic material, and a connection. And a connection layer 13 made of a conductive material disposed on the portion 10a. The connection layer 13 may be made of a magnetic material. Each edge part of the outer periphery and the inner periphery of the insulating layer 11 has a rounded slope shape.

  The top pole layer 12 includes a track width defining layer 12a, a coupling portion layer 12b, and a yoke portion layer 12c. The track width defining layer 12 a is disposed on the recording gap layer 9 and the insulating layer 11 in a region from the slope portion on the medium facing surface 20 side to the medium facing surface 20 side of the insulating layer 11. The track width defining layer 12a is formed on the recording gap layer 9, and is formed on the tip portion serving as the magnetic pole portion of the upper magnetic pole layer 12 and the slope portion on the medium facing surface 20 side of the insulating layer 11, and the yoke portion. And a connection portion connected to the layer 12c. The width of the tip is equal to the recording track width. The width of the connection part is larger than the width of the tip part.

  The coupling portion layer 12b is disposed on the lower magnetic pole layer 19 at a position where the contact hole 9a is formed. The yoke portion layer 12c connects the track width defining layer 12a and the connecting portion layer 12b. The end of the yoke portion layer 12 c on the medium facing surface 20 side is disposed at a position away from the medium facing surface 20. The yoke portion layer 12c is connected to the lower magnetic pole layer 19 through the coupling portion layer 12b.

  The thin film magnetic head further includes a coupling portion layer 12b and an insulating layer 14 made of an inorganic insulating material such as alumina disposed around the coupling portion layer 12b. The top surfaces of the track width defining layer 12a, the coupling portion layer 12b, the connection layer 13 and the insulating layer 14 are flattened.

  The thin film magnetic head further includes a second layer portion 15 of a thin film coil disposed on the insulating layer 14. The second layer portion 15 is made of a conductive material such as copper (Cu). In FIG. 3, reference numeral 15 a represents a connection portion of the second layer portion 15 that is connected to the connection portion 10 a of the first layer portion 10 of the thin film coil via the connection layer 13. The second layer portion 15 is wound around the coupling portion layer 12b.

  The thin film magnetic head further includes an insulating layer 16 disposed so as to cover the second layer portion 15 of the thin film coil and the insulating layer 14 therearound. Each edge part of the outer periphery and the inner periphery of the insulating layer 16 has a rounded slope shape. A part of the yoke portion layer 12 c is disposed on the insulating layer 16.

  The thin film magnetic head further includes an overcoat layer 17 disposed so as to cover the upper magnetic pole layer 12. The overcoat layer 17 is made of alumina, for example.

  Next, an outline of a method for manufacturing the thin film magnetic head shown in FIGS. 3 and 4 will be described. In this manufacturing method, first, the insulating layer 2 is formed on the substrate 1 by a sputtering method or the like to a thickness of 0.2 to 5 μm, for example. Next, the first shield layer 3 is formed in a predetermined pattern on the insulating layer 2 by plating or the like. Next, although not shown, an insulating layer made of alumina, for example, is formed on the entire surface. Next, the insulating layer is polished by chemical mechanical polishing (hereinafter referred to as CMP) until the first shield layer 3 is exposed, and the upper surfaces of the first shield layer 3 and the insulating layer are planarized.

  Next, the MR element 5, the two bias magnetic field application layers 6, and the insulating layer 7 are formed on the first shield layer 3. Next, the second shield layer 8 is formed on the MR element 5, the bias magnetic field applying layer 6 and the insulating layer 7. The second shield layer 8 is formed by, for example, a plating method or a sputtering method. Next, the separation layer 18 is formed on the second shield layer 8 by sputtering or the like. Next, the lower magnetic pole layer 19 is formed on the separation layer 18 by, for example, plating or sputtering.

  Next, the recording gap layer 9 is formed to a thickness of, for example, 50 to 300 nm on the lower magnetic pole layer 19 by sputtering or the like. Next, in order to form a magnetic path, the recording gap layer 9 is partially etched at the center portion of a thin film coil to be formed later to form a contact hole 9a.

  Next, the first layer portion 10 of the thin film coil is formed on the recording gap layer 9 to a thickness of 2 to 3 μm, for example. The first layer portion 10 is wound around the contact hole 9a.

  Next, an insulating layer 11 made of an organic insulating material having fluidity when heated, such as a photoresist, is formed in a predetermined pattern so as to cover the first layer portion 10 of the thin film coil and the recording gap layer 9 around the first layer portion 10. . Next, heat treatment is performed at a predetermined temperature in order to flatten the surface of the insulating layer 11. By this heat treatment, the edge portions of the outer periphery and inner periphery of the insulating layer 11 become rounded slope shapes.

  Next, the track width of the upper magnetic pole layer 12 is defined on the recording gap layer 9 and the insulating layer 11 in a region from the slope portion on the medium facing surface 20 side to be described later to the medium facing surface 20 side in the insulating layer 11. Layer 12a is formed.

  When the track width defining layer 12a is formed, at the same time, the coupling portion layer 12b is formed on the lower magnetic pole layer 19 at the position where the contact hole 9a is formed, and the connection layer 13 is formed on the connection portion 10a. To do.

  Next, magnetic pole trimming is performed. In other words, in the peripheral region of the track width defining layer 12a, at least a part of the magnetic gap portions of the recording gap layer 9 and the lower magnetic pole layer 19 on the recording gap layer 9 side is etched using the track width defining layer 12a as a mask. As a result, as shown in FIG. 3, a trim structure is formed in which the widths of at least a part of the magnetic pole portions of the upper magnetic pole layer 12, the magnetic gap portions of the recording gap layer 9 and the lower magnetic pole layer 19 are aligned. The According to this trim structure, an increase in effective track width due to the spread of magnetic flux in the vicinity of the recording gap layer 9 can be prevented.

  Next, the insulating layer 14 is formed to a thickness of, for example, 3 to 4 μm on the entire top surface of the laminate formed by the steps so far. Next, the insulating layer 14 is polished and planarized by CMP, for example, to reach the surfaces of the track width defining layer 12a, the coupling portion layer 12b, and the connection layer 13.

  Next, the second layer portion 15 of the thin film coil is formed on the planarized insulating layer 14 to a thickness of, for example, 2 to 3 μm. The second layer portion 15 is wound around the connection portion layer 12b.

  Next, an insulating layer 16 made of an organic insulating material having fluidity when heated, such as a photoresist, is formed in a predetermined pattern so as to cover the second layer portion 15 of the thin film coil and the insulating layer 14 therearound. Next, heat treatment is performed at a predetermined temperature in order to flatten the surface of the insulating layer 16. By this heat treatment, the edge portions of the outer periphery and the inner periphery of the insulating layer 16 have a rounded slope shape. Next, the yoke portion layer 12c is formed on the track width defining layer 12a, the insulating layers 14 and 16, and the coupling portion layer 12b.

  Next, the overcoat layer 17 is formed so as to cover the entire top surface of the laminate formed by the steps so far. Next, wiring, terminals, and the like are formed on the overcoat layer 17. Finally, the slider including the above layers is machined to form the medium facing surface 20 to complete a thin film magnetic head including a recording head and a reproducing head.

  The thin film magnetic head manufactured in this way includes a medium facing surface 20 facing the recording medium, a reproducing head, and a recording head. The reproducing head is disposed in the vicinity of the medium facing surface 20 in order to detect a signal magnetic field from the recording medium. The configuration of the reproducing head will be described in detail later.

  The recording head includes magnetic pole portions facing each other on the medium facing surface 20 side, and is magnetically coupled to the lower magnetic pole layer 19 and the upper magnetic pole layer 12, and the magnetic pole portion of the lower magnetic pole layer 19 and the upper magnetic pole layer 12. A recording gap layer 9 provided between the magnetic pole portion and the thin film coil 10 disposed at least partially between the lower magnetic pole layer 19 and the upper magnetic pole layer 12 in an insulated state. 15. In this thin film magnetic head, as shown in FIG. 2, the length from the medium facing surface 20 to the end of the insulating layer 11 on the medium facing surface 20 side is the throat height TH. The throat height refers to the length (height) from the medium facing surface 20 to a position where the distance between the two pole layers starts to increase. 3 and 4 show the longitudinal magnetic recording system recording head, but in the thin film magnetic head to which the present embodiment is applied, the recording head is a perpendicular magnetic recording system recording head. Also good.

  Next, the configuration of the reproducing head will be described in detail with reference to FIG. 1 and FIG. FIG. 1 is a cross-sectional view showing a cross section parallel to the medium facing surface of the read head, and FIG. 2 is a cross sectional view showing a cross section perpendicular to the medium facing surface and the substrate of the read head. As shown in FIGS. 1 and 2, the reproducing head includes a first shield layer 3 and a second shield layer 8 that are arranged at a predetermined interval, and a first shield layer 3 and a second shield. And an MR element 5 arranged between the layer 8. The MR element 5 and the second shield layer 8 are stacked on the first shield layer 3.

  The reproducing head is further arranged adjacent to the two sides of the MR element 5, two bias magnetic field application layers 6 for applying a bias magnetic field to the MR element 5, the first shield layer 3 and the MR element. An insulating layer 4 is provided between the element 5 and the bias magnetic field applying layer 6.

  The bias magnetic field application layer 6 is configured using a hard magnetic layer (hard magnet), a laminated body of a ferromagnetic layer and an antiferromagnetic layer, or the like. Specifically, the bias magnetic field application layer 6 is formed of, for example, CoPt or CoCrPt. The insulating layer 4 is made of alumina, for example.

  The MR element 5 is a current confinement type CPP-GMR element. In this MR element 5, a sense current, which is a magnetic signal detection current, intersects with the surface of each layer constituting the MR element 5, for example, a direction perpendicular to the surface of each layer constituting the MR element 5. Washed away. The first shield layer 3 and the second shield layer 8 are configured so that the sense current is directed to the MR element 5 in a direction intersecting with the surfaces of the layers constituting the MR element 5, for example, the surfaces of the layers constituting the MR element 5. It also serves as a pair of electrodes for flowing in a direction perpendicular to the direction. A pair of electrodes may be provided above and below the MR element 5 separately from the first shield layer 3 and the second shield layer 8. The resistance value of the MR element 5 changes according to an external magnetic field, that is, a signal magnetic field from a recording medium. The resistance value of the MR element 5 can be obtained from the sense current. In this way, the information recorded on the recording medium can be reproduced by the reproducing head.

  FIG. 1 and FIG. 2 show an example of the configuration of the MR element 5. The MR element 5 includes a free layer 25 that is a ferromagnetic layer whose magnetization direction changes in response to a signal magnetic field, a fixed layer 23 that is a ferromagnetic layer whose magnetization direction is fixed, and the free layer 25 and the fixed layer. And a spacer layer 24 disposed therebetween. In the present embodiment, of the fixed layer 23 and the free layer 25, the fixed layer 23 is disposed at a position closer to the first shield layer 3. The MR element 5 further includes an antiferromagnetic layer 22 disposed on the side of the fixed layer 23 opposite to the spacer layer 24, and an underlayer disposed between the first shield layer 3 and the antiferromagnetic layer 22. 21 and a protective layer 26 disposed between the free layer 25 and the second shield layer 8. In the MR element 5 shown in FIGS. 1 and 2, an underlayer 21, an antiferromagnetic layer 22, a fixed layer 23, a spacer layer 24, a free layer 25, and a protective layer 26 are disposed on the first shield layer 3 in this order. Are stacked. In the present embodiment, the fixed layer 23 corresponds to the first magnetic layer in the present invention, and the free layer 25 corresponds to the second magnetic layer in the present invention.

  The antiferromagnetic layer 22 is a layer that fixes the magnetization direction in the fixed layer 23 by exchange coupling with the fixed layer 23. The underlayer 21 is provided to improve the crystallinity and orientation of each layer formed thereon, and in particular to improve exchange coupling between the antiferromagnetic layer 22 and the fixed layer 23. The protective layer 26 is a layer for protecting each layer below it.

  The thickness of the foundation layer 21 is 2 to 8 nm, for example. As the underlayer 21, for example, a stacked body of a Ta layer and a NiFeCr layer is used.

The thickness of the antiferromagnetic layer 22 is, for example, 5 to 30 nm. The antiferromagnetic layer 22 is, for example, Pt, consists Ru, Rh, Pd, Ni, Cu, Ir, and at least one M _II selected from the group consisting of Cr and Fe, the antiferromagnetic material containing Mn ing. Among these, the content of Mn is preferably 35 atomic% or more and 95 atomic% or less, and the content of the other element M _II is preferably 5 atomic% or more and 65 atomic% or less. This antiferromagnetic material exhibits antiferromagnetism without heat treatment, and exhibits non-heat treatment antiferromagnetic material that induces an exchange coupling magnetic field with the ferromagnetic material, and exhibits antiferromagnetism by heat treatment. There is a heat treatment type antiferromagnetic material. The antiferromagnetic layer 22 may be composed of either of them. Non-heat-treatment type antiferromagnetic materials include Mn alloys having a γ phase, and specifically, RuRhMn, FeMn, IrMn, and the like. The heat-treated antiferromagnetic material includes a Mn alloy having a regular crystal structure, and specifically includes PtMn, NiMn, PtRhMn, and the like.

  Note that a hard magnetic layer made of a hard magnetic material such as CoPt may be provided as a layer for fixing the magnetization direction in the fixed layer 23 instead of the antiferromagnetic layer 22 as described above. In this case, Cr, CrTi, TiW or the like is used as the material for the underlayer 21.

  In the fixed layer 23, the magnetization direction is fixed by exchange coupling at the interface with the antiferromagnetic layer 22. The fixed layer 23 in the present embodiment has an outer layer 31, a nonmagnetic intermediate layer 32, and an inner layer 33 that are sequentially stacked on the antiferromagnetic layer 22, and is a so-called synthetic fixed layer. The outer layer 31 and the inner layer 33 include, for example, a ferromagnetic layer made of a ferromagnetic material containing at least Co in the group consisting of Co and Fe. The outer layer 31 and the inner layer 33 are antiferromagnetically coupled, and the magnetization directions are fixed in opposite directions. The outer layer 31 has a thickness of 3 to 7 nm, for example. The thickness of the inner layer 33 is, for example, 3 to 10 nm.

  The thickness of the nonmagnetic intermediate layer 32 is, for example, 0.35 to 1.0 nm. The nonmagnetic intermediate layer 32 is made of, for example, a nonmagnetic material including at least one selected from the group consisting of Ru, Rh, Ir, Re, Cr, Zr, and Cu. The nonmagnetic intermediate layer 32 is for generating antiferromagnetic exchange coupling between the inner layer 33 and the outer layer 31 and fixing the magnetization of the inner layer 33 and the magnetization of the outer layer 31 in opposite directions. is there. The magnetization of the inner layer 33 and the magnetization of the outer layer 31 are opposite to each other not only when the directions of these two magnetizations differ from each other by 180 °, but also when the directions of the two magnetizations differ by 180 ° ± 20 °. including.

  As will be described in detail later, the spacer layer 24 in the present embodiment includes an insulating portion and a conductive portion so as to be mixed in a cross section parallel to the surface.

  The thickness of the free layer 25 is, for example, 2 to 10 nm. The free layer 25 is composed of a ferromagnetic layer having a small coercive force. The free layer 25 may include a plurality of laminated ferromagnetic layers.

  The thickness of the protective layer 26 is, for example, 0.5 to 20 nm. As the protective layer 26, for example, a stacked body of a Cu layer and a Ru layer is used.

  Note that at least one of the inner layer 33 and the free layer 25 may include a Heusler alloy layer.

  Next, the operation of the thin film magnetic head according to the present embodiment will be described. The thin film magnetic head records information on a recording medium with a recording head, and reproduces information recorded on the recording medium with a reproducing head.

  In the reproducing head, the direction of the bias magnetic field by the bias magnetic field application layer 6 is orthogonal to the direction perpendicular to the medium facing surface 20. In the MR element 5, when there is no signal magnetic field, the magnetization direction of the free layer 25 is aligned with the direction of the bias magnetic field. On the other hand, the magnetization direction of the fixed layer 23 is fixed in a direction perpendicular to the medium facing surface 20.

  In the MR element 5, the magnetization direction of the free layer 25 changes in accordance with the signal magnetic field from the recording medium, whereby the relative angle between the magnetization direction of the free layer 25 and the magnetization direction of the fixed layer 23 is changed. As a result, the resistance value of the MR element 5 changes. The resistance value of the MR element 5 can be obtained from the potential difference between the shield layers 3 and 8 when a sense current is passed through the MR element 5 by the first and second shield layers 3 and 8. In this way, the information recorded on the recording medium can be reproduced by the reproducing head.

  In MR element 5 in the present embodiment, spacer layer 24 includes an insulating portion and a conductive portion so as to be mixed in a cross section parallel to the surface. Therefore, in MR element 5 in the present embodiment, current locally flows through the conductive portion in spacer layer 24. Thereby, in the MR element 5 in the present embodiment, the area resistance, the resistance value, and the resistance change amount of the MR element 5 are reduced as compared with the general CPP-GMR element in which the spacer layer is configured only by the nonmagnetic conductive layer. While being able to enlarge, the influence of a spin torque can be suppressed.

  Next, a method for manufacturing the MR element 5 according to the present embodiment will be described. In the manufacturing method of the MR element 5 according to the present embodiment, the base layer 21, the antiferromagnetic layer 22, the fixed layer 23, the spacer layer 24, the free layer 25, and the protective layer 26 are sequentially formed on the first shield layer 3. Each process to form is provided. Each layer other than the spacer layer 24 is formed by sputtering, for example. Here, the step of forming the fixed layer 23 corresponds to the step of forming the first magnetic layer in the present invention, and the step of forming the free layer 25 corresponds to the step of forming the second magnetic layer in the present invention. .

  Hereinafter, a method for forming the spacer layer 24 in the present embodiment will be described in detail with reference to FIGS. 9 to 14 are cross-sectional views of the stacked body in the formation process of the spacer layer 24, respectively.

  In the method of forming the spacer layer 24 in the present embodiment, first, as shown in FIG. 9, the first nonmagnetic metal layer 41 made of a nonmagnetic metal material is formed on the fixed layer 23. As the nonmagnetic metal material constituting the first nonmagnetic metal layer 41, for example, Cu is used. The first nonmagnetic metal layer 41 is formed by sputtering, for example. In addition, the thickness of the first nonmagnetic metal layer 41 at the initial formation is set to 2 nm, for example.

  Next, a second nonmagnetic metal layer 42 made of a nonmagnetic metal material is formed on the first nonmagnetic metal layer 41 so as to have an island-like structure or have an uneven surface. Here, a laminated body composed of the first nonmagnetic metal layer 41 and the second nonmagnetic metal layer 42 is referred to as a laminated film 51. FIG. 9 shows an example in which the second nonmagnetic metal layer 42 is formed so as to have an island structure. By continuing the film formation of the second nonmagnetic metal layer 42 from the state shown in FIG. 9, the second nonmagnetic metal layer 42 can be formed so that the upper surface has irregularities. As the nonmagnetic metal material constituting the second nonmagnetic metal layer 42, for example, Ag is used. Since the Ag thin film easily grows in an island shape, Ag is particularly preferable as the nonmagnetic metal material constituting the second nonmagnetic metal layer 42. The second nonmagnetic metal layer 42 is formed by, for example, a vacuum evaporation method. The second nonmagnetic metal layer 42 may be formed by sputtering, but it is preferable to form the second nonmagnetic metal layer 42 by vacuum evaporation because the second nonmagnetic metal layer 42 is likely to grow in an island shape. In addition, the maximum thickness of the second nonmagnetic metal layer 42 at the beginning of formation is, for example, 1 nm.

  Next, as shown in FIG. 10, the upper surface of the laminated film 51 is etched so that the second nonmagnetic metal layer 42 is removed and irregularities are formed on the upper surface of the first nonmagnetic metal layer 41. To do. This step corresponds to the first etching in the present invention. Etching in this step is performed using, for example, ion milling. As shown in FIG. 9, the upper surface of the laminated film 51 in the state before this etching is uneven. Therefore, when the upper surface of the laminated film 51 is etched so that the second nonmagnetic metal layer 42 is removed, the upper surface of the first nonmagnetic metal layer 41 is shown in FIG. 9 as shown in FIG. Irregularities having a shape corresponding to the irregularities on the upper surface of the laminated film 51 are formed. When Cu is used as the material of the first nonmagnetic metal layer 41 and Ag is used as the material of the second nonmagnetic metal layer 42, the first nonmagnetic metal layer 41 and the second nonmagnetic metal layer are used. The etching rate in 42 ion milling is almost equal.

  In this step, the upper surface of the laminated film 51 is etched by a thickness larger than the maximum thickness of the second nonmagnetic metal layer 42 at the beginning of formation so that the second nonmagnetic metal layer 42 is surely removed. Also good. For example, when the thickness of the first nonmagnetic metal layer 41 at the initial formation is 2 nm and the maximum thickness of the second nonmagnetic metal layer 42 at the initial formation is 1 nm, the upper surface of the laminated film 51 is, for example, 1. You may etch only 2 nm. In this case, the thickness of the first nonmagnetic metal layer 41 after etching is 1.8 nm at the portion corresponding to the convex portion and 0.8 nm at the portion corresponding to the concave portion.

  Note that a thin oxide layer is formed by oxidation near the upper surface of the laminated film 51 before the upper surface of the laminated film 51 is etched. However, the oxide layer is completely removed by etching the upper surface of the laminated film 51.

Next, as shown in FIG. 11, an insulating layer 43 made of an insulating material is formed on the first nonmagnetic metal layer 41. The formation process of the insulating layer 43 is performed after the etching process shown in FIG. 10 without once releasing the stacked body into the atmosphere. As an insulating material constituting the insulating layer 43, for example, Al ₂ O ₃ is used. The insulating layer 43 is formed by sputtering, for example. The thickness of the insulating layer 43 at the beginning of formation is such that a recess in the upper surface of the first nonmagnetic metal layer 41 is filled with the insulating layer 43. Of the insulating layer 43 at the beginning of formation, the thickness of the portion disposed on the convex portion on the upper surface of the first nonmagnetic metal layer 41 is disposed on the concave portion on the upper surface of the first nonmagnetic metal layer 41. It is smaller than the thickness of the part. The maximum thickness of the insulating layer 43 at the beginning of formation is, for example, in the range of 1.5 to 2.0 nm.

  Next, as shown in FIG. 12, the protrusion on the upper surface of the first nonmagnetic metal layer 41 is exposed, and the insulating layer 43 remains in the recess on the upper surface of the first nonmagnetic metal layer 41. A part of the insulating layer 43 is etched by wet etching. This step corresponds to the second etching in the present invention. In this step, as the etchant, for example, a low concentration developer is used.

  As described above, the thickness of the portion of the insulating layer 43 at the time of formation formed on the convex portion on the top surface of the first nonmagnetic metal layer 41 is the concave portion on the top surface of the first nonmagnetic metal layer 41. It is smaller than the thickness of the part arrange | positioned in. The etching rate in wet etching is such that the portion of the insulating layer 43 disposed on the convex portion on the top surface of the first nonmagnetic metal layer 41 is on the top surface of the first nonmagnetic metal layer 41. It is larger than the portion arranged in the recess. Therefore, by adjusting the etching time, the convex portion on the upper surface of the first nonmagnetic metal layer 41 is exposed, and the insulating layer 43 remains in the concave portion on the upper surface of the first nonmagnetic metal layer 41. In addition, a part of the insulating layer 43 can be etched.

  After etching a part of the insulating layer 43 by wet etching, in order to remove a thin oxide layer formed on the exposed portion of the upper surface of the first nonmagnetic metal layer 41, for example, ion milling is used to remove the first oxide layer 43. The top surfaces of the nonmagnetic metal layer 41 and the insulating layer 43 may be slightly etched.

  Next, as shown in FIG. 13, a third nonmagnetic metal layer 44 made of a nonmagnetic metal material is formed on the first nonmagnetic metal layer 41 and the insulating layer 43. As the nonmagnetic metal material constituting the third nonmagnetic metal layer 44, for example, Cu is used. The third nonmagnetic metal layer 44 is formed by, for example, sputtering. The thickness of the third nonmagnetic metal layer 44 is, for example, 1.5 nm. The upper surface of the third nonmagnetic metal layer 44 formed by sputtering is substantially flat.

  Through the above steps, the spacer layer 24 including the first nonmagnetic metal layer 41, the insulating layer 43, and the third nonmagnetic metal layer 44 is formed. Thereafter, a free layer 25 is formed on the spacer layer 24 as shown in FIG.

  13 is omitted, and after the step shown in FIG. 12, the third nonmagnetic metal layer 44 is not formed and the first nonmagnetic metal layer 41 and the insulating layer 43 are not formed. Alternatively, the free layer 25 may be formed.

  FIG. 15 shows a cross section of the spacer layer 24 at the position indicated by the line 15-15 in FIG. This cross section is a cross section parallel to the surface of the spacer layer 24. In this cross section, an insulating portion 63 formed by the insulating layer 43 and a conductive portion 61 formed by the first nonmagnetic metal layer 41 are mixed. As shown in FIG. 14, when the cross section perpendicular to the surface of the spacer layer 24 is viewed, the edge of the insulating layer 43 disposed in the vicinity of the boundary between the insulating portion 63 and the conductive portion 61 is the first non-magnetic. The metal layer 41 has a shape that slightly climbs on the convex portion on the upper surface.

  In the example shown in FIG. 15, there are a plurality of isolated conductive portions 61 in a cross section parallel to the surface of the spacer layer 24, and an insulating portion 63 is disposed between the plurality of isolated conductive portions 61. Yes. Such a distribution is obtained when the second nonmagnetic metal layer 42 is formed so as to have an island-like structure in the process shown in FIG. 9 or a plurality of isolated on the upper surface of the second nonmagnetic metal layer 42. This can be realized when the second nonmagnetic metal layer 42 is formed so as to form a convex portion. On the contrary, in the cross section parallel to the surface of the spacer layer 24, there are a plurality of isolated insulating parts 63, and the spacers are arranged such that the conductive parts 61 are arranged between the isolated insulating parts 63. It is also possible to form layer 24. This can be realized when the second nonmagnetic metal layer 42 is formed so that a plurality of isolated recesses are formed on the upper surface of the second nonmagnetic metal layer 42 in the step shown in FIG. it can.

[First experiment]
Next, by adjusting the etching time in the process shown in FIG. 12 (hereinafter referred to as wet etching time), as shown in FIG. A first experiment in which it has been confirmed that the spacer layer 24 having a structure in which the portion 61 is mixed can be realized. In this experiment, samples 1 to 4 having the configuration shown in FIG. 16 were prepared. Samples 1 to 4 include a lower electrode film 73, an MR element 5 disposed on the lower electrode film 73, an insulating layer 74 disposed on the lower electrode film 73 and around the MR element 5, and an MR element. An upper electrode film 78 disposed on the element 5 and the insulating layer 74 is provided. The configuration of the MR element 5 in the samples 1 to 4 is the same as that of the MR element 5 shown in FIG. The lower electrode film 73 was formed of NiFe. The upper electrode film 78 was made of Cu. The insulating layer 74 was made of Al ₂ O ₃ . The MR elements 5 in the samples 1 to 4 were processed by ion milling so that the shape of the upper surface was a circular truncated cone shape having a diameter of 0.3 μm.

The specific film configuration of the MR element 5 in Samples 1 to 4 is shown in Table 1 below. Hereinafter, a CoFe alloy containing M atom% Co and N atom% Fe is represented as Co _M Fe _N. A NiFe alloy containing 81 atomic% Ni and 19 atomic% Fe is represented as Ni ₈₁ Fe ₁₉ .

The spacer layers 24 in the samples 1 to 4 were formed according to the steps shown in FIGS. 9 to 13 under the following conditions. In the process shown in FIG. 9, Cu was used as the nonmagnetic metal material constituting the first nonmagnetic metal layer 41, and the thickness of the first nonmagnetic metal layer 41 at the initial formation was 2 nm. The second nonmagnetic metal layer 42 was formed to have an island structure. Ag was used as the nonmagnetic metal material constituting the second nonmagnetic metal layer 42, and the maximum thickness of the second nonmagnetic metal layer 42 at the initial formation was 1 nm. In the process shown in FIG. 10, the upper surface of the laminated film 51 is etched by 1.2 nm. Accordingly, the thickness of the first nonmagnetic metal layer 41 after etching in the portion corresponding to the recess is 0.8 nm. In the process shown in FIG. 11, Al ₂ O ₃ was used as the insulating material constituting the insulating layer 43, and the maximum thickness of the insulating layer 43 at the initial formation was 1.5 nm. In the process shown in FIG. 12, an aqueous solution of TMAH (tetramethylammonium hydroxide) having a concentration of 2.38% was used as a developing solution as an etchant. The etching rate of the Al ₂ O ₃ film having a uniform thickness with respect to the developer was 0.05 nm / second. In the step shown in FIG. 12, the etching rate of the portion of the insulating layer 43 disposed on the convex portion on the upper surface of the first nonmagnetic metal layer 41 with respect to the developer is 0.05 nm / second. Is expected to be larger. Samples 1 to 4 have different wet etching times. In the process shown in FIG. 13, Cu is used as the nonmagnetic metal material constituting the third nonmagnetic metal layer 44, and the thickness of the third nonmagnetic metal layer 44 is 1.5 nm.

In Table 1, the 1.5-nm-thick layer in which the substance is expressed as “Cu / Al ₂ O ₃ ” in the spacer layer 24 is less than Cu in the cross-section parallel to the surface of the spacer layer 24 in the spacer layer 24. The region where the conductive portion 61 and the insulating portion 63 made of Al ₂ O ₃ coexist is shown. In Table 1, the Cu layer having a thickness of 0.8 nm in the spacer layer 24 represents a lower part of the spacer layer 24 than the above region. In Table 1, the 1.5 nm-thickness Cu layer in the spacer layer 24 represents the upper part of the spacer layer 24 above the above-described region.

  In the experiment, Comparative Example 1 was also prepared, which was different from Samples 1 to 4 only in the configuration and formation method of the spacer layer. The specific film configuration of the MR element in Comparative Example 1 is shown in Table 2 below. Comparative Example 1 includes a spacer layer made of a Cu layer having a thickness of 3 nm formed by sputtering instead of the spacer layer 24 in the samples 1 to 4. Therefore, the MR element in Comparative Example 1 is a general CPP-GMR element.

In the experiment, the sheet resistance (Ω · μm ² ) and the MR ratio (%) were measured for the MR element 5 in Samples 1 to 4 and the MR element in Comparative Example 1. Table 3 below shows the sheet resistance and MR ratio for Comparative Example 1, and also shows the wet etching time, sheet resistance, and MR ratio for Samples 1 to 4.

  As can be seen from Table 3, in the sample 1 in which the wet etching time is 10 seconds, the sheet resistance is significantly larger than those in the samples 2 to 4. Sample 1 has a small MR ratio. Therefore, in the sample 1, since the wet etching time is short, the protrusion on the upper surface of the first nonmagnetic metal layer 41 is not exposed in the process shown in FIG. 12, and the first nonmagnetic metal layer 41 is not exposed. It is considered that the insulating layer 43 remains on the entire upper surface. On the other hand, in the samples 2 to 4 where the wet etching time is 15 seconds or more, the sheet resistance is significantly smaller than that of the sample 1, and the MR ratio is large. From this, under the conditions in the first experiment, by setting the wet etching time to 15 seconds or longer, the protrusion on the upper surface of the first nonmagnetic metal layer 41 is exposed in the step shown in FIG. It can be seen that a conductive portion is formed in 24. However, if the wet etching time is too long, the entire insulating layer 43 is removed in the process shown in FIG. 12, and an insulating portion is not formed in the spacer layer 24. Therefore, there is an upper limit to the wet etching time. Since the MR element in the comparative example 1 is a general CPP-GMR element, in the comparative example 1, the sheet resistance is significantly smaller than those of the samples 2 to 4.

  From the above first experiment, it can be seen that the spacer layer 24 having a structure in which the insulating portion 63 and the conductive portion 61 are mixed in a cross section parallel to the surface of the spacer layer 24 can be realized by adjusting the wet etching time. In order to realize this structure, the wet etching time varies depending on the insulating material constituting the insulating layer 43, the thickness of the insulating layer 43 at the beginning of formation, the etchant, and the like. Therefore, the wet etching time may be appropriately set according to these conditions. .

[Second experiment]
Next, a second experiment in which the MR ratio is compared between the MR element 5 manufactured by the manufacturing method according to the present embodiment and the MR element manufactured by the manufacturing method that performs the oxidation process when forming the spacer layer will be described. . In this experiment, the MR ratio was compared between the sample 3 produced in the first experiment and the comparative example 2 which is different from the sample 3 only in the configuration and formation method of the spacer layer. The MR element 5 in the sample 3 is manufactured by the manufacturing method according to the present embodiment. The specific film structure of the MR element in Comparative Example 2 is shown in Table 4 below. The spacer layer in Comparative Example 2 was formed as follows. First, a Cu layer having a thickness of 0.5 nm was formed on the inner layer 33. Next, an AlCu layer having a thickness of 1 nm was formed on the Cu layer. Next, the AlCu layer was irradiated with a rare gas ion beam to separate Al and Cu. Next, the AlCu layer was oxidized to oxidize Al to form a layer in which an insulating portion made of Al ₂ O ₃ and a conductive portion made of Cu were mixed. Next, a Cu layer having a thickness of 0.5 nm was formed on this layer to complete the spacer layer in Comparative Example 2. The MR element in Comparative Example 2 was fabricated so as to have the same area resistance as that of the MR element 5 in Sample 3 (0.25Ω · μm ² ).

  Table 5 below shows the sheet resistance and MR ratio for Comparative Example 2 and Sample 3.

  As can be seen from Table 5, in the comparative example 2 and the sample 3, the area resistance of the MR element is equal, but the MR ratio of the MR element is larger in the sample 3. From this, it can be seen that the MR element 5 manufactured by the manufacturing method according to the present embodiment has a higher MR ratio than the MR element manufactured by the manufacturing method in which the oxidation process is performed when the spacer layer is formed. The MR ratio varies depending on whether or not the oxidation treatment is performed when the spacer layer is formed, because the amount of magnetization disappearance in the portion of the fixed layer near the interface with the spacer layer varies depending on whether or not the oxidation treatment is performed.

[Third experiment]
Next, a third experiment in which the magnetization amount of the fixed layer in Comparative Example 2 and Sample 3 is compared will be described. In the third experiment, Comparative Example 3 that is a sample for measuring the amount of magnetization corresponding to Comparative Example 2 and Sample 5 that is a sample for measuring the amount of magnetization corresponding to Sample 3 were produced. Neither Comparative Example 3 nor Sample 5 is provided with an antiferromagnetic layer and a free layer. Therefore, in Comparative Example 3 and Sample 5, the fixed layer is disposed on the base layer, and the protective layer is disposed on the spacer layer. Other configurations and manufacturing methods in Comparative Example 3 are the same as those of Comparative Example 2, and other configurations and manufacturing methods of Sample 5 are the same as those of Sample 3. The reason why the antiferromagnetic layer and the free layer were not included in Comparative Example 3 and Sample 5 was to measure only the magnetization amount of the fixed layer in Comparative Example 3 and Sample 5. In the third experiment, the magnetization amount of the fixed layer in Comparative Example 3 and Sample 5 was measured using a vibrating sample magnetometer.

Comparative Example 3 and Sample 5 include a fixed layer having the same configuration. The amount of magnetization of the fixed layer when there is no decrease in the amount of magnetization accompanying the formation of the spacer layer is known in advance. Based on this, the amount of decrease in the magnetization amount of the fixed layer in Comparative Example 3 and the amount of decrease in the magnetization amount of the fixed layer in Sample 5 were obtained. The amount of decrease in the magnetization amount of the fixed layer in Comparative Example 3 corresponds to approximately 0.5 nm when converted to the thickness of the Co ₅₀ Fe ₅₀ layer that is the uppermost layer of the fixed layer. On the other hand, the amount of decrease in the magnetization amount of the fixed layer in Sample 5 corresponds to approximately 0.1 nm when converted to the thickness of the Co ₅₀ Fe ₅₀ layer that is the uppermost layer of the fixed layer. Therefore, in the MR element 5 manufactured by the manufacturing method according to the present embodiment, the interface between the fixed layer and the spacer layer is larger than that of the MR element manufactured by the manufacturing method in which the oxidation process is performed when forming the spacer layer. It can be seen that the amount of magnetization disappearance is small in the vicinity of. As a result, the MR element 5 manufactured by the manufacturing method according to the present embodiment is considered to have a higher MR ratio than the MR element manufactured by the manufacturing method in which the oxidation process is performed when the spacer layer is formed.

[Fourth experiment]
Next, a fourth experiment in which variation in characteristics is compared between the MR element 5 manufactured by the manufacturing method according to the present embodiment and the MR element manufactured by the manufacturing method in which the oxidation process is performed when the spacer layer is formed. explain. In this experiment, 36 pieces of each of Comparative Example 4 having the same film configuration as Comparative Example 2 but having a different shape and Sample 6 having the same film structure as Sample 3 but having a different shape were prepared. The MR elements in Comparative Example 4 and Sample 6 each have a quadrangular frustum shape in which the shape of the upper surface of the protective layer is a rectangle having a length of 0.1 μm and a width of 0.1 μm. The 36 comparative examples 4 and 36 samples 6 were each formed on one wafer. 36 comparative examples 4 are arranged in a vertical direction and a horizontal direction with 6 pieces each at 15 mm intervals on one wafer, and the center of the area where the 36 comparative examples 4 are arranged coincides with the center of the wafer. Arranged to be. Similarly, sixteen samples 6 are arranged on a single wafer in the vertical direction and the horizontal direction at a distance of 15 mm, and the center of the region where the 36 samples 6 are arranged is the center of the wafer. Arranged to match.

In the fourth experiment, the resistance values of the MR elements were measured for the 36 comparative examples 4 and 36 samples 6, and the standard deviation was obtained. The standard deviation of the resistance value is one index indicating the variation in characteristics of the MR element. Table 6 below shows the area resistance (Ω · μm ² ), the average resistance value (Ω), and the standard deviation (%) of the resistance value for Comparative Example 4 and Sample 6.

  As can be seen from Table 6, the standard deviation of the resistance value of Sample 6 is smaller than the standard deviation of the resistance value of Comparative Example 4. From this, it can be seen that the MR element 5 manufactured by the manufacturing method according to the present embodiment has less variation in characteristics than the MR element manufactured by the manufacturing method in which the oxidation process is performed when the spacer layer is formed. .

  As described above, according to the manufacturing method of the MR element 5 according to the present embodiment, the spacer layer 24 including the insulating portion 63 and the conductive portion 61 can be formed without performing the oxidation treatment. Therefore, according to the present embodiment, the MR ratio of the MR element 5 is not reduced due to the oxidation process. Further, according to the present embodiment, the distribution of the insulating portion 63 and the conductor portion 61 is not determined by the oxidation process, but is determined by the shape of the second nonmagnetic metal layer 42. Specifically, when the second nonmagnetic metal layer 42 is formed to have an island structure, the distribution of the insulating portion 63 and the conductor portion 61 is determined by the distribution of the islands. Further, when the second nonmagnetic metal layer 42 is formed so that the upper surface thereof has unevenness, the distribution of the insulating portion 63 and the conductor portion 61 is determined by the unevenness distribution on the upper surface. In any of these cases, the distribution of the insulating portion 63 and the conductor portion 61 can be made uniform as compared with the case where the distribution of the insulating portion 63 and the conductor portion 61 is determined by the oxidation treatment. From the above, according to the present embodiment, it is possible to suppress a decrease in the MR ratio of the MR element 5 and to reduce variations in characteristics of the MR element 5.

  A slider, a head gimbal assembly, a head arm assembly, and a magnetic disk device including a thin film magnetic head to which this embodiment is applied will be described below. First, the slider 210 will be described with reference to FIG. In the magnetic disk device, the slider 210 is disposed so as to face a magnetic disk that is a disk-shaped recording medium that is rotationally driven. The slider 210 includes a substrate 211 mainly composed of the substrate 1 and the overcoat layer 17 in FIG. The base body 211 has a substantially hexahedral shape. One of the six surfaces of the substrate 211 faces the magnetic disk. A medium facing surface 20 is formed on this one surface. When the magnetic disk rotates in the z direction in FIG. 5, an air flow passing between the magnetic disk and the slider 210 generates a lift in the slider 210 in the lower direction in the y direction in FIG. 5. The slider 210 floats from the surface of the magnetic disk by this lifting force. Note that the x direction in FIG. 5 is the track crossing direction of the magnetic disk. Near the end of the slider 210 on the air outflow side (lower left end in FIG. 5), a thin film magnetic head 100 to which this embodiment is applied is formed.

  Next, the head gimbal assembly 220 will be described with reference to FIG. The head gimbal assembly 220 includes a slider 210 and a suspension 221 that elastically supports the slider 210. The suspension 221 is, for example, a leaf spring-shaped load beam 222 formed of stainless steel, a flexure 223 that is provided at one end of the load beam 222 and is joined to the slider 210 to give the slider 210 an appropriate degree of freedom. And a base plate 224 provided at the other end of the beam 222. The base plate 224 is attached to an arm 230 of an actuator for moving the slider 210 in the track crossing direction x of the magnetic disk 262. The actuator has an arm 230 and a voice coil motor that drives the arm 230. In the flexure 223, a part to which the slider 210 is attached is provided with a gimbal part for keeping the posture of the slider 210 constant.

  The head gimbal assembly 220 is attached to the arm 230 of the actuator. A structure in which the head gimbal assembly 220 is attached to one arm 230 is called a head arm assembly. Further, a head gimbal assembly 220 attached to each arm of a carriage having a plurality of arms is called a head stack assembly.

  FIG. 6 shows the head arm assembly. In this head arm assembly, a head gimbal assembly 220 is attached to one end of the arm 230. A coil 231 that is a part of the voice coil motor is attached to the other end of the arm 230. A bearing portion 233 attached to a shaft 234 for rotatably supporting the arm 230 is provided at an intermediate portion of the arm 230.

  Next, the head stack assembly and the magnetic disk device will be described with reference to FIGS. FIG. 7 is an explanatory view showing a main part of the magnetic disk device, and FIG. 8 is a plan view of the magnetic disk device. The head stack assembly 250 has a carriage 251 having a plurality of arms 252. A plurality of head gimbal assemblies 220 are attached to the plurality of arms 252 so as to be arranged in the vertical direction at intervals. A coil 253 that is a part of the voice coil motor is attached to the carriage 251 on the side opposite to the arm 252. The head stack assembly 250 is incorporated in a magnetic disk device. The magnetic disk device has a plurality of magnetic disks 262 attached to a spindle motor 261. Two sliders 210 are arranged for each magnetic disk 262 so as to face each other with the magnetic disk 262 interposed therebetween. Further, the voice coil motor has permanent magnets 263 arranged at positions facing each other with the coil 253 of the head stack assembly 250 interposed therebetween.

  The head stack assembly 250 and the actuator excluding the slider 210 correspond to the positioning device in the present invention, and support the slider 210 and position it relative to the magnetic disk 262.

  In the magnetic disk apparatus, the slider 210 is moved with respect to the magnetic disk 262 by the actuator so that the slider 210 is positioned with respect to the magnetic disk 262. The thin film magnetic head included in the slider 210 records information on the magnetic disk 262 by the recording head, and reproduces information recorded on the magnetic disk 262 by the reproducing head.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 17 is a cross-sectional view showing a cross section parallel to the medium facing surface of the read head to which the present embodiment is applied. The configuration of the reproducing head in the present embodiment is the same as that of the first embodiment except for the configuration of the MR element 5. The MR element 5 in the present embodiment has a base layer 21, a free layer 25, a spacer layer 24, a fixed layer 23, an antiferromagnetic layer 22, and a protective layer 26 that are sequentially stacked on the first shield layer 3. is doing. As described above, in the MR element 5 in the present embodiment, the free layer 25 of the fixed layer 23 and the free layer 25 is disposed at a position closer to the first shield layer 3. In the present embodiment, the free layer 25 corresponds to the first magnetic layer in the present invention, and the fixed layer 23 corresponds to the second magnetic layer in the present invention.

  The pinned layer 23 in the present embodiment includes an inner layer 33, a nonmagnetic intermediate layer 32, and an outer layer 31 that are sequentially stacked on the spacer layer 24, and is a so-called synthetic pinned layer.

  For example, a NiCr layer is used as the base layer 21 in the present embodiment. As the protective layer 26 in the present embodiment, for example, a laminated body of a Ru layer and a Ta layer is used. The thicknesses and materials of the other layers constituting the MR element 5 in the present embodiment are the same as those in the first embodiment.

  In the manufacturing method of the MR element 5 according to the present embodiment, the base layer 21, the free layer 25, the spacer layer 24, the fixed layer 23, the antiferromagnetic layer 22, and the protective layer 26 are sequentially formed on the first shield layer 3. Each process to form is provided. Each layer other than the spacer layer 24 is formed by sputtering, for example. In the present embodiment, the step of forming the free layer 25 corresponds to the step of forming the first magnetic layer in the present invention, and the step of forming the fixed layer 23 is a step of forming the second magnetic layer in the present invention. Corresponding to The method for forming the spacer layer 24 in the present embodiment is the same as that in the first embodiment.

  Next, the MR ratio and the coercive force of the free layer were compared between the MR element 5 manufactured by the manufacturing method according to the present embodiment and the MR element manufactured by the manufacturing method that performs the oxidation treatment when forming the spacer layer. The experiment will be described. The coercivity of the free layer is one of the soft magnetic properties of the free layer, and the free layer is required to have a small coercivity. In this experiment, a sample 7 similar to the sample 3 used in the description of the first embodiment was created. The sample 7 is different from the sample 3 only in the film configuration of the MR element 5. The specific film configuration of the MR element 5 in the sample 7 is shown in Table 7 below. The formation method of the spacer layer 24 in the sample 7 is the same as that in the sample 3.

  In the experiment, Comparative Example 5 was produced, which was different from Sample 7 only in the configuration and formation method of the spacer layer. The configuration and formation method of the spacer layer in Comparative Example 5 are the same as those of Comparative Example 2 used in the description of the first embodiment. That is, in Comparative Example 5, oxidation treatment is performed when the spacer layer is formed.

Both Comparative Example 5 and Sample 7 were fabricated such that the area resistance of the MR element was 0.25 Ω · μm ² . In the experiment, for the comparative example 5 and the sample 7, the area resistance of the MR element and the coercive force of the free layer were measured. The results are shown in Table 8 below. Note that 1 Oe is 79.6 A / m.

  As can be seen from Table 8, the MR elements of Comparative Example 5 and MR element 5 of Sample 7 have the same area resistance, but the MR ratio of MR element 5 of Sample 7 is larger than the MR ratio of MR element of Comparative Example 5. . Further, the coercivity of the free layer in Sample 7 is smaller than the coercivity of the free layer in Comparative Example 5. From this, in the MR element 5 manufactured by the manufacturing method according to the present embodiment, the coercive force of the free layer is smaller than that of the MR element manufactured by the manufacturing method that performs the oxidation treatment when forming the spacer layer, It can be seen that the MR ratio increases. If oxidation treatment is performed at the time of forming the spacer layer, the soft magnetic characteristics of the free layer are deteriorated by the oxidation treatment, and the coercive force is increased. As a result, the MR ratio is considered to be reduced. In contrast, in the MR element 5 manufactured by the manufacturing method according to the present embodiment, since the oxidation process is not performed when the spacer layer is formed, the soft magnetic characteristics of the free layer are not deteriorated, and as a result, the MR ratio is large. It is considered to be.

  Also in the present embodiment, the variation in characteristics of the MR element 5 can be reduced as in the first embodiment. Other configurations, operations, and effects in the present embodiment are the same as those in the first embodiment.

  In addition, this invention is not limited to said each embodiment, A various change is possible. For example, the fixed layer 23 is not limited to the synthetic fixed layer. In the embodiment, a thin film magnetic head having a structure in which a reproducing head is formed on the substrate side and a recording head is stacked thereon has been described. However, the stacking order may be reversed. When used as a read-only device, the thin film magnetic head may be configured to include only the reproducing head.

1 is a cross-sectional view showing a cross section parallel to a medium facing surface of a read head to which a first embodiment of the present invention is applied. 1 is a cross-sectional view showing a cross section perpendicular to a medium facing surface and a substrate of a read head to which a first embodiment of the present invention is applied. 1 is a cross-sectional view showing a cross section perpendicular to a medium facing surface and a substrate of a thin film magnetic head to which a first embodiment of the present invention is applied. 1 is a cross-sectional view showing a cross section parallel to a medium facing surface of a magnetic pole portion of a thin film magnetic head to which a first embodiment of the present invention is applied. 1 is a perspective view showing a slider including a thin film magnetic head to which the first embodiment of the present invention is applied. FIG. 1 is a perspective view showing a head arm assembly including a thin film magnetic head to which a first embodiment of the present invention is applied. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram for explaining a main part of a magnetic disk device including a thin film magnetic head to which a first embodiment of the present invention is applied. 1 is a plan view of a magnetic disk device including a thin film magnetic head to which the first embodiment of the present invention is applied. It is sectional drawing of the laminated body in 1 process of the formation method of the spacer layer in the 1st Embodiment of this invention. It is sectional drawing of the laminated body in the process following the process shown in FIG. It is sectional drawing of the laminated body in the process following the process shown in FIG. It is sectional drawing of the laminated body in the process following the process shown in FIG. It is sectional drawing of the laminated body in the process following the process shown in FIG. It is sectional drawing of the laminated body in the process following the process shown in FIG. It is sectional drawing which shows the cross section of the spacer layer in the position shown by the 15-15 line in FIG. It is sectional drawing which shows the structure of the sample produced by experiment. It is sectional drawing which shows the cross section parallel to the medium opposing surface of the reproducing head to which the 2nd Embodiment of this invention is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Insulating layer, 3 ... 1st shield layer, 4 ... Insulating layer, 5 ... MR element, 6 ... Bias magnetic field application layer, 7 ... Insulating layer, 8 ... 2nd shield layer, 9 ... Recording Gap layer, 10 ... first layer portion of thin film coil, 12 ... upper magnetic pole layer, 15 ... second layer portion of thin film coil, 17 ... overcoat layer, 18 ... separation layer, 19 ... lower magnetic pole layer, 20 ... medium facing Surface, 22 ... antiferromagnetic layer, 23 ... fixed layer, 24 ... spacer layer, 25 ... free layer.

Claims (4)

A first magnetic layer;
A second magnetic layer;
A spacer layer disposed between the first magnetic layer and the second magnetic layer,
One of the first magnetic layer and the second magnetic layer is a layer whose magnetization direction is fixed,
The other of the first magnetic layer and the second magnetic layer is a layer whose magnetization direction changes according to an external magnetic field,
The spacer layer includes an insulating portion and a conductive portion so as to be mixed in a cross section parallel to the surface,
A method of manufacturing a magnetoresistive effect element in which a current for detecting a magnetic signal is caused to flow in a direction intersecting a plane of each layer,
Forming the first magnetic layer;
Forming the spacer layer on the first magnetic layer;
Forming the second magnetic layer on the spacer layer,
The step of forming the spacer layer includes
Forming a first nonmagnetic metal layer made of a nonmagnetic metal material on the first magnetic layer;
Forming a second nonmagnetic metal layer made of a nonmagnetic metal material on the first nonmagnetic metal layer so as to have an island-like structure or an upper surface having irregularities;
The first nonmagnetic metal layer and the second nonmagnetic metal layer are formed such that the second nonmagnetic metal layer is removed and irregularities are formed on the upper surface of the first nonmagnetic metal layer. A first etching step for etching the upper surface of the laminated film;
Forming an insulating layer by depositing an insulating material on the first nonmagnetic metal layer without performing an oxidation treatment after the first etching step;
Etching a part of the insulating layer by wet etching so that the convex portion on the upper surface of the first nonmagnetic metal layer is exposed and the insulating layer remains in the concave portion on the upper surface of the first nonmagnetic metal layer. A second etching step ,
Forming a third nonmagnetic metal layer made of a nonmagnetic metal material on the first nonmagnetic metal layer and the insulating layer after the second etching step ;
The method of manufacturing a magnetoresistive element, wherein the insulating portion is formed by the insulating layer, and the conductive portion is formed by the first nonmagnetic metal layer.   The magnetic material according to claim 1, wherein the nonmagnetic metal material constituting the first nonmagnetic metal layer is Cu, and the nonmagnetic metal material constituting the second nonmagnetic metal layer is Ag. A method of manufacturing a resistance effect element.   3. The method of manufacturing a magnetoresistive element according to claim 1, wherein the second nonmagnetic metal layer is formed by a vacuum deposition method. Method for manufacturing a magneto-resistance effect element according to any one of claims 1 to 3 non-magnetic metallic material constituting the non-magnetic metal layer of the third is characterized by a Cu.

Images