JP2009087474A - Cpp magnetic read head and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a CPP read head having an excellent property. <P>SOLUTION: A CPP read head 11 has hard bias films 115 at both sides of a magnetic reluctance sensor 112. The hard bias film 115 has a lower layer hard magnetic layer 151 and an upper layer hard magnetic layer 152 which are laminated. Saturation magnetic flux density and residual magnetic flux density of the upper layer hard magnetic layer 152 are larger than that of the lower layer hard magnetic layer 151. Coercive force of the lower layer hard magnetic layer 151 is larger than that of the upper layer hard magnetic layer 152. An upper shield 113 has a flat part overlapped to a free layer 215, and width of the flat part is larger than that of the free layer 215. Shield gap can be made small by forming a hard bias film by hard magnetic layers of which the magnetic properties are different, while the shield can be flatted. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a structure of a CPP (Current Perpendicular Plane) type magnetic read head and a manufacturing method thereof, and more particularly to a hard bias film structure in a CPP magnetic read head and a method of forming the same.

  A hard disk drive (HDD) includes a magnetic recording medium and a magnetic head, and data on the magnetic recording medium is read and written by the magnetic head. A magnetic head in the HDD is composed of a write head that records information as a magnetization signal on a magnetic recording medium (magnetic disk) and a read head that reads a signal recorded as a magnetization signal on the magnetic recording medium. . The read head is composed of a magnetoresistive layered body composed of a plurality of magnetic thin films and a non-magnetic thin film, and reads a signal using the magnetoresistive effect, so that it is called a magnetoresistive head.

  There are several types of laminated structures of magnetoresistive effect heads, and they are classified into AMR heads, GMR heads, CPP-GMR heads, TMR heads and the like based on the principles of magnetoresistance used. AMR (magnetoresistance effect), GMR (giant magnetoresistance effect), CPP-GMR effect (Current Perpendicular Plane GMR effect), and TMR effect (tunnel magnetoresistance effect) are used to enter the read head from the magnetic recording medium, respectively. The incoming magnetic field signal is extracted as a voltage change.

  Currently, with the progress of higher recording information density, a more sensitive information signal reproduction method is required. At a recording density of 70 to 150 (Gb / in 2), a TMR read head with a very high MR ratio is advantageous in terms of improving sensitivity. Then, it is considered that a CPP-GMR read head or the like becomes mainstream for an ultrahigh recording density exceeding 150 (Gb / in 2). For example, Patent Document 1 discloses CPP-GMR. TMR and CPP-GMR are different from CIP-GMR (Current In Plane GMR) in which a sense current flows parallel to the film surface of the magnetoresistive effect laminate, and are perpendicular to the element sensor film surface, that is, the element sensor film surface. This is a method of flowing a sense current in the stacking direction. Such a method is called a CPP method. Such a read head is called a CPP read head.

  FIG. 17 is a cross-sectional view schematically showing the structure and configuration of the CPP read head 71. The magnetoresistive sensor 712 is between the lower shield 711 and the upper shield 713. The lower shield 711 and the upper shield 713 function as a magnetic shield and also serve as a lower electrode and an upper electrode that supply a sense current to the magnetoresistive sensor 712. An upper magnetic isolation film 714 made of a conductor is formed below the upper shield 713.

  The magnetoresistive sensor 712 includes a sensor base layer 271, an antiferromagnetic film 272, a fixed layer 273, a nonmagnetic intermediate layer 274, a free layer 275, and a sensor cap film 276, which are sequentially stacked from the lower layer side. An exchange interaction with the antiferromagnetic film 272 acts on the fixed layer 273 and its magnetization direction is fixed. When the read head 71 is a TMR head, the nonmagnetic intermediate layer 274 is formed of an insulator such as alumina (AL2O3) or magnesium oxide (MgO). When using CPP-GMR, the nonmagnetic intermediate layer 274 is formed of Cu. It is formed using a non-magnetic conductor such as an alloy. The track width of the free layer 275 is indicated by Twf.

  The magnetoresistive head operates by utilizing the fact that the resistance changes due to the change in the magnetization direction of the free layer 275 relative to the magnetization direction of the fixed layer 273. That is, when the magnetization direction of the free layer 275 changes with the information magnetic field from the magnetic disk with respect to the magnetization direction of the fixed layer 273, the resistance value (current value) of the magnetoresistive sensor 712 changes. The read head 71 can detect a narrowed external information magnetic field by detecting the resistance value (current value) of the magnetoresistive sensor 712. Hard bias films 715 exist on the left and right sides of the magnetoresistive sensor element 712. A bias magnetic field from the hard bias film 715 is applied to the free layer 275 so as to make the free layer 275 a single magnetic domain and stabilize the magnetization operation of the free layer. The hard bias film 715 is formed on the hard bias base film 716. A junction insulating film 717 is formed as a lower layer of the hard bias base film 716. The insulating film 717 exists between the hard bias base film 716, the lower shield film 711, and the magnetoresistive sensor 712, and prevents the sense detection current from flowing outside the magnetoresistive sensor 712.

Next, a manufacturing process of the sensor element portion of the CPP read head 71 will be described with reference to FIG. First, a multilayer film constituting the magnetoresistive sensor 712 is deposited and formed on the substrate on which the lower shield film is formed by a sputtering film forming method (S31).
Thereafter, in order to form the magnetoresistive sensor element shape, an end portion in the depth direction and a shape in the track width direction are formed with respect to the track width direction using a photoresist coating-etching technique. When forming the track width shape, a hard bias film is disposed and formed at the end of the free layer. The process is as follows. A resist is applied on the multilayer film of the magnetoresistive sensor 712, and a resist is formed by patterning (S32). Further, the track width of the magnetoresistive sensor 712 is formed by etching using ion milling (S33). Thereafter, the side end portion of the magnetoresistive sensor 712 is oxidized as necessary (S34), and then an insulating film 717 is formed (S35). Further, a hard bias base film 716 and a hard bias film 715 are formed (S36). Thereafter, the resist is lifted off (S37), and an upper magnetic isolation film 714 and an upper shield film 713 are formed (S38).
Japanese Patent Laid-Open No. 3-154217

  The hard bias film 715 needs to exhibit a large coercive force and a high magnetic flux density in order to obtain a strong magnetic field strength and stability. However, in general, a magnetic material exhibiting a large coercive force has a low magnetic flux density, and a magnetic material exhibiting a high magnetic flux density does not exhibit a high coercive force. For this reason, in the conventional hard bias film 715 design, a material exhibiting a high magnetic flux density is selected from magnetic materials having a predetermined coercive force value or more that satisfies the magnetization stability so as to satisfy the required stability and the amount of magnetic flux. The film thickness will be set to. Therefore, in order to improve and secure the stability of the head characteristics, it is necessary to set the thickness of the hard bias film to be thick.

  In the generation of CPP-TMR / GMR heads with higher recording density, it is necessary to reduce the free layer track width Twf and the shield interval Gs. However, the current hard bias film 715 cannot be thinned in order to ensure the stability of the head characteristics. For this reason, the upper shield film 713 has a concave shape on the magnetoresistive sensor 712, and the shield interval cannot be flattened, or the flattened width becomes small.

  As described above, if the flattening of the upper shield 713 (shield interval) with respect to the free layer track width Twf is not sufficient, the effect of the upper shield 713 at the end of the magnetoresistive sensor 712 is reduced, and the reading blur width is increased. is there. In particular, this problem becomes significant in a read head having a small shield interval Gs. From this point of view, there is a limit to narrowing the shield interval Gs.

  A CPP magnetic read head according to an aspect of the present invention includes a magnetoresistive sensor film having a free layer, a fixed layer, and a nonmagnetic intermediate layer between the free layer and the fixed layer, and the magnetic A hard bias film made of a hard magnetic material for stabilizing the magnetization state of the free layer formed on both sides of the resistance sensor film, and a sensing current to flow in the stacking direction of the magnetoresistive sensor film, And an insulating film disposed on both ends of the magnetoresistive sensor film, and an upper shield and a lower shield formed so as to sandwich the magnetoresistive sensor film in the vertical direction. Each of the hard bias films has a first hard magnetic layer and a second hard magnetic layer laminated. The saturation magnetic flux density and residual magnetic flux density of the first hard magnetic layer are larger than those of the second hard magnetic layer. The coercivity of the second hard magnetic layer is greater than the coercivity of the first hard magnetic layer. The upper shield has a flat portion that overlaps the free layer, and the width of the flat portion is equal to or greater than the width of the free layer. The hard bias film can reduce the thickness of the hard bias film, and the width of the upper shield flat portion is equal to or larger than the width of the free layer, so that the characteristics of the read head can be improved.

  Preferably, at least a part of the first hard magnetic layer and at least a part of the free layer have the same height position. Thereby, the magnetization flux of the first hard magnetic layer can be effectively given to the free layer. Further preferably, the height position of the lower surface of the first hard magnetic layer and the height position of the lower surface of the free layer coincide. Thereby, the flux of the first hard magnetic layer can be more effectively applied to the free layer. Alternatively, the fixed layer, the nonmagnetic intermediate layer, and the free layer are sequentially stacked from the bottom to the top, and the first hard magnetic layer is formed above the second hard magnetic layer. Preferably it is. Thereby, the selection range of the film thickness of the second hard magnetic layer is widened.

Preferably, a distance between the first hard magnetic layer and the magnetoresistive sensor film end is smaller than a distance between the second hard magnetic layer and the magnetoresistive sensor film end. This
The flux of the first hard magnetic layer can be more effectively applied to the free layer while maintaining the insulation reliability.

  Each of the first hard magnetic layer and the second hard magnetic layer has an inner film thickness at a position separated from the side edge of the free layer by a distance greater than or equal to the distance between the lower shield and the upper shield. Preferably, the width of the flat portion of the upper shield is approximately equal to a value obtained by adding a value twice the distance between the lower shield and the upper shield and the width of the free layer. . As a result, excellent CPP read head characteristics can be realized, and the stability of the hard bias film can be enhanced.

  The first hard magnetic layer and the second hard magnetic layer have a single-layer structure or a multilayer structure formed of an alloy containing Co as a main component, and the residual magnetic flux density of the first hard magnetic layer is 1. The residual magnetic flux density of the second hard magnetic layer is preferably 1.0 T or less. Thereby, an excellent hard bias film can be realized.

  Another aspect of the present invention is a method of manufacturing a CPP magnetic read head. This manufacturing method forms a magnetoresistive sensor film having a free layer, a fixed layer, and a nonmagnetic intermediate layer located between the free layer and the fixed layer. In order to flow a detection current in the lamination direction of the magnetoresistive sensor film, insulating films are formed on both side ends of the magnetoresistive sensor film. In the vacuum chamber, a lower hard magnetic layer constituting a part of the hard bias film is attached to the insulating film on the opposite side of the magnetoresistive sensor film by ion beam deposition. In the vacuum chamber, a portion of the lower hard magnetic layer on the side of the magnetoresistive sensor film is removed by ion beam etching. In the vacuum chamber, an upper hard magnetic layer constituting a part of the hard bias film is deposited on the lower hard magnetic layer by ion beam deposition, and the upper hard magnetic layer and the lower hard magnetic layer are adhered. One of the layers has a higher saturation and residual flux density and a smaller coercivity than the other. In the vacuum chamber, a part of the upper hard magnetic layer on the side of the magnetoresistive sensor film is removed by ion beam etching. In the vacuum chamber, a hard bias cap film is formed on the upper hard magnetic layer. Thereby, a CPP read head having a hard bias film exhibiting excellent characteristics can be efficiently manufactured.

  Preferably, the magnetoresistive sensor element is formed using ion beam deposition and ion beam etching. In the ion beam deposition and the ion beam etching in forming the magnetoresistive sensor element shape, the lower hard magnetic layer, and the upper hard magnetic layer, the ion beam and the sputtered particle beam formed a resist pattern. Incident on the inclined surface while changing the incident angle on the substrate. The incident angle is limited to a preselected angle range. Thereby, the shape and thickness of the hard bias film can be accurately controlled. Desirably, these processes are continuously performed without breaking the vacuum in the same vacuum layer by using an ion beam deposition apparatus and an ion beam etching apparatus. As a result, a CPP read head having good characteristics can be efficiently manufactured.

  According to the present invention, the characteristics of the CPP magnetic read head can be improved.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. In addition, in each drawing, the same code | symbol is attached | subjected to the same element, and duplication description is abbreviate | omitted as needed for clarification of description. In the embodiment described below, the present invention is applied to a read head of a hard disk drive (HDD). The read head of the present embodiment is a CPP (Current Perpendicular Plane) type read head in which a sense current flows in the stacking direction of the magnetoresistive sensor film (direction perpendicular to the film surface).

  Before describing the features of this embodiment, the overall configuration of the magnetic head will be described first. FIG. 1 is a cross-sectional view schematically showing the structure of the magnetic head 1. The magnetic head 1 reads and writes magnetic data from and to the magnetic disk 3. The magnetic head 1 has a read head 11 and a write head 12 from the running direction side (leading side). The magnetic head 1 is formed on the trailing side of the slider 2 (the side opposite to the leading side). The read head 11 has a lower shield 111, a magnetoresistive sensor 112, and an upper shield 113 from the leading side.

  The write head 12 has a thin film coil 121 and a recording magnetic pole 122. The thin film coil 121 is surrounded by an insulator 123. The write head 12 is an inductive element that generates a magnetic field between the recording magnetic poles 122 by a current flowing through the thin film coil 121 and records magnetic data on the magnetic disk 11. The read head 11 is a magnetoresistive element, and includes a magnetoresistive sensor 112 having magnetic anisotropy, and magnetic data recorded on the magnetic disk 2 by its resistance value that changes according to the magnetic field from the magnetic disk 2. Is read. The read head of this embodiment is a CPP read head, and the lower shield 111 and the upper shield 113 are used as electrodes for supplying a sense current to the magnetoresistive sensor 112.

  The magnetic head 1 is formed on an AlTiC (AlTiC) substrate constituting the slider 3 by using a thin film forming process. The magnetic head 1 and the slider 3 constitute a head slider. The head slider floats on the magnetic disk 3, and the magnetic disk facing surface 21 is called ABS (Air Bearing Surface). The magnetic head 1 includes a protective film 13 such as alumina around the write head 12 and the read head 11, and the entire magnetic head 1 is protected by the protective film 13.

  FIG. 2 is a cross-sectional view schematically showing the configuration of the read head 11 of this embodiment. FIG. 2 schematically shows a cross-sectional structure of the head slider as viewed from the ABS surface 21 side. The lower side in FIG. 2 is the leading side, and the upper side is the trailing side. In this specification, the AlTiC substrate side on which the read head 11 is formed, that is, the slider 2 side is the lower side, and the trailing side, which is the opposite side, is the upper side. Further, both sides centered in the stacking direction when viewed from the ABS surface 21 are defined as left and right sides. Each layer of the read head 11 is sequentially formed from the lower side. The read head 11 of this embodiment is a CPP read head such as a TMR (Tunneling Magneto Resistance) head or a CPP-MR (Magneto Resistance) head, and the sense current flows in the vertical direction in FIG.

  The magnetoresistive sensor 112 is between the lower shield 111 and the upper shield 113. A distance between the upper surface of the lower shield 111 and the lower surface of the upper shield 113 is shown as a shield interval Gs. Gs is a shield interval at a position overlapping with the magnetoresistive sensor 112. The lower shield 111 and the upper shield 113 are made of a conductive magnetic material, function as a magnetic shield, and function as a lower electrode and an upper electrode that supply a sense current to the magnetoresistive sensor 112. The lower shield 111 and the upper shield 113 are made of, for example, an alloy containing Ni, Fe, Co, or the like. An upper shield base film 114 made of a conductor is formed below the upper shield 113.

  The magnetoresistive sensor 112 is a multilayer film composed of a plurality of layers. The magnetoresistive sensor 112 typically includes a sensor base layer 211, an antiferromagnetic film 212, a fixed layer 213, a nonmagnetic intermediate layer 214, a free layer 215, a sensor cap film 216, and the like, which are sequentially stacked from the lower layer side. It is a laminated multilayer film having Each layer is in physical contact with an adjacent layer. The sensor underlayer 211 is formed of a nonmagnetic material such as Ta or NiFeCo alloy, and may be formed of a single layer or a laminated structure. The antiferromagnetic film 212 is formed of an antiferromagnetic material such as PtMn. The fixed layer 213 in FIG. 2 is a laminated fixed layer, and is composed of a two-layered ferromagnetic film made of a CoFe alloy or the like and a nonmagnetic layer made of Ru or the like therebetween. The two layers of ferromagnetic films are coupled by exchange interaction, and the magnetization is stabilized. An exchange interaction with the antiferromagnetic film 212 acts on the lower ferromagnetic film, and its magnetization direction is fixed. Note that the fixed layer 213 may have a single-layer structure.

  When the read head 11 is a TMR head, the nonmagnetic intermediate layer 214 is formed of an insulator such as magnesium oxide (MgO) and functions as a tunnel barrier. On the other hand, when the read head 11 is a CPP-GMR head, the nonmagnetic intermediate layer 214 is formed using a nonmagnetic conductor such as Cu. The free layer 215 is formed of a metal magnetic material such as a NiFe alloy or a CoFe alloy. The free layer 215 can also be a single layer or a laminated structure. The track width of the free layer 215 is indicated by Twf. The sensor cap film 216 is made of a nonmagnetic conductive material such as Ta.

  The read head 11 has junction insulating films 118 on both left and right ends of the magnetoresistive sensor 112 so that a desired sense current flows in the magnetoresistive sensor 112. The junction insulating film 118 extends further outward from the magnetoresistive sensor 112 side end. The junction insulating film 118 can be formed of, for example, Al2O3. The junction insulating film 118 insulates between the upper shield film 113 and the lower seal film 111 outside the magnetoresistive sensor 112 and blocks the sense current outside the magnetoresistive sensor 112.

  When the relative magnetization direction of the free layer 215 with respect to the magnetization direction of the fixed layer 213 is changed by the magnetic field from the magnetic disk 3, the resistance value (current value) of the magnetoresistive sensor 112 changes. The read head 11 can detect the external signal magnetic field thus narrowed. In order to suppress Barkhausen noise and the like due to magnetic domain non-uniformity of the free layer 215, hard bias films 115, which are magnetic domain control films, exist on both the left and right sides of the magnetoresistive sensor 112. Typically, the hard bias film 115 is made of a Co alloy, such as a CoCrPt alloy or a CoPt alloy.

  The bias magnetic field from the hard bias film 115 controls the magnetic domain of the free layer 215 and functions to make the free layer 215 a single magnetic domain. The left and right hard bias films 115 are line symmetric with respect to the direction perpendicular to the film surface. A junction insulating film 118 exists between the magnetoresistive sensor 112 and the hard bias film 115. The hard bias film 115 is formed in contact with the hard bias base film 116. A hard bias cap film 117 is formed on the hard bias film 115.

  Preferably, the hard bias base film 116 has a two-layer structure. The upper base film controls the crystal state of the hard bias film 115. The lower base film is an amorphous layer and controls the crystal state of the upper base film. Since the upper base film is required to have a high coercive force and a high magnetic flux density, it is preferably formed of a Co alloy containing Co as a main component, such as CoCrPt. At this time, the saturation magnetic flux density and the like can be adjusted by adjusting the composition of the Co alloy. Also, in order to generate a uniform and strong bias magnetic field with little variation, it is important to control and adjust the polycrystalline orientation state of the Co alloy magnetic film. Here, by forming an upper base film with Cr or Cr alloy and adjusting and controlling the orientation state thereof, the polycrystalline orientation of the Co alloy magnetic film as the hard bias film 115 can be controlled.

  The orientation of the upper base film made of Cr or Cr alloy can be adjusted and controlled by the amorphous base film which is the base film. Only a specific orientation state of Cr and Co can be realized on the layer of the magnetoresistive sensor film 112 which is an almost face-centered cubic structure type polycrystalline film. By selecting the material of the amorphous base film, the orientation state of the Co alloy hard bias film 115 can be adjusted and controlled to a desired state.

  As a material for the amorphous underlayer, for example, Ni or Co is used as a base layer to contain an additive element. Examples of the element to be added include P, Cr, Zr, Nb, and Hf. One or more elements are added to Ni or Co to form an amorphous structure. Further, it is important to adjust the surface energy of the amorphous base film surface by adjusting the oxidation state by oxidation treatment.

  The hard bias film 115 of this embodiment is composed of a plurality of hard magnetic layers having different magnetic characteristics. In the preferred example shown in FIG. 2, the hard bias film 115 includes a lower hard magnetic layer 151 and an upper hard magnetic layer 152. One of the two hard magnetic layers is a high magnetic flux density layer, and the other is a high coercive force layer.

  Specifically, one hard magnetic layer has a larger magnetic flux density than the other hard magnetic layer, and further has a smaller coercive force than the other hard magnetic layer. Both the residual magnetic flux density Br and the saturation magnetic flux density Bs of one hard magnetic layer are larger than the other. In general, a magnetic material exhibiting a large coercive force does not exhibit a high magnetic flux density. The high coercive force layer stabilizes the magnetization of the high magnetic flux density layer. Thus, by laminating two hard magnetic layers having different magnetic characteristics, the entire hard bias film 115 can exhibit a high magnetic flux density and a high coercive force.

  Preferably, the high magnetic flux density layer is formed of a CoPtX alloy material. X is an element selected from Cr, Ta, W, Ti, V, Zr, Nb, Mo, and Rh. The high magnetic flux density hard magnetic layer may have a plurality of elements therein. Preferably, the Pt composition is 18 at% or less and the X composition is 5 at% or less. Preferably, the high coercive force hard magnetic layer is formed of a CoPtX alloy material. X is an element selected from Cr, Ta, W, Ti, V, Zr, Nb, Mo, and Rh. The high coercive force hard magnetic layer may have a plurality of elements therein. Preferably, the Pt composition is 10 at% or more.

  The high magnetic flux density layer preferably has a residual magnetic flux density Br of 1T or higher, and more preferably has a residual magnetic flux density Br of 1.3T or higher. Further, the high magnetic flux density hard magnetic layer preferably has a saturation magnetic flux density Bs of 1.2 T or more, and more preferably has a saturation magnetic flux density Bs of 1.5 T or more. The high coercive force layer preferably has a coercive force Hc of 1200 Oe or more, and more preferably has a coercive force Hc of 1500 Oe or more.

  The high magnetic flux density and high coercive force of the hard bias film 115 enable the hard bias film 115 to be thinned. By thinning the hard bias film 115 in the vicinity of the magnetoresistive sensor 112, the shield interval Gs is reduced, and the upper shield 113 and the lower shield 111 are flattened at a position overlapping with the magnetoresistive sensor 112 and in the vicinity of the magnetoresistive sensor 112. be able to.

  When the upper shield 113 and the lower shield 111 have a concave shape at a position overlapping with the magnetoresistive sensor 112 (see the prior art in FIG. 17), the shielding effect is reduced at the end of the magnetoresistive sensor 112 and the reading blur width is increased. End up. Therefore, it is preferable that the lower surface of the upper shield 113 and the upper surface of the lower shield 111 are flat over the free layer track width Twf. In the read head 11 of FIG. 2, the portions of the lower surface of the upper shield 113 and the upper surface of the lower shield 111 that overlap with the magnetoresistive sensor 112 are substantially flat.

  The flat width Usw of the upper shield 113 and the flat width Lsw of the lower shield 111 are preferably equal to or larger than the free layer track width Twf. Furthermore, it is preferable that the flat widths Usw and Lsw spread on both the left and right sides with respect to Twf. In FIG. 2, the upper surface of the hard bias film 115 at the end of the magnetoresistive sensor 112 and in the vicinity thereof is below the lower surface of the upper shield 113 that overlaps the magnetoresistive sensor 112 (the upper surface of the sensor cap film 216). Its lower surface is above the upper surface of the lower shield 111 that overlaps the magnetoresistive sensor 112.

  As a result, the flat portions of the upper shield 113 and the lower shield 111 extend to the left and right sides of the free layer 215. Preferably, the upper shield flat width Usw and the lower shield flat width Lsw are larger than the free layer track width Twf and have sufficient dimensions. Specifically, the upper shield flat width Usw and the lower shield flat width Lsw are substantially the same as the free layer track width Twf + 2Gs. The above is preferable. As a result, the output characteristics can be maximized while suppressing the reading bleeding at the end of the free layer 215.

  The thickness of the hard bias film 115 in this embodiment is thin in the vicinity of the magnetoresistive sensor 112 and thick in a portion away from the vicinity of the magnetoresistive sensor 112. Further, the hard bias film 115 has a thin film portion having a substantially constant thickness on the magnetoresistive sensor 112 side. Since the hard bias film 115 has a thick film portion away from the magnetoresistive sensor 112, magnetic instability of the hard bias film 115 due to thinning in the vicinity of the magnetoresistive sensor 112 can be eliminated.

  That is, by increasing the thickness of a part of the hard bias film 115, the magnetic stability can be improved, and the magnetic stability of the thin hard bias film 115 layer in the vicinity of the magnetoresistive sensor 112 can be improved by the magnetic field from the part. it can. Preferably, the thickness Th2 of the hard bias film 115 is approximately twice the thickness Th1 of the inner flat portion at a position separated from the side edge of the free layer 215 by Gs or more. Each of the lower hard magnetic layer 151 and the upper hard magnetic layer 152 preferably satisfies the above thickness condition.

  FIGS. 3A to 3C show a preferred structure example of the hard bias film 115 in the vicinity of the magnetoresistive sensor 112. 3A to 3C show the structure of the hard bias film 115 in the vicinity of the right side of the magnetoresistive sensor 112, the structure is the same on the left side. 3A to 3C, the lower hard magnetic layer 151 is a high coercivity hard magnetic layer, and the upper hard magnetic layer 152 is a high magnetic flux density hard magnetic layer.

  By thinning the hard bias film 115 in the vicinity of the magnetoresistive sensor 112, the bias magnetic field to the free layer 215 can be controlled more effectively. By matching the height position of the thinned high magnetic flux density layer 152 to the free layer 215, the bias magnetic field applied to the free layer 215 can be localized and optimized.

  The high magnetic flux density layer 152 is preferably opposed to the free layer 215. That is, at least a part of the high magnetic flux density layer 152 coincides with a height position of at least a part of the free layer 215. Thereby, the strong magnetic field of the high magnetic flux density layer 152 can be effectively applied to the free layer 215. The lower surface of the high magnetic flux density layer 152 preferably coincides with the lower surface of the free layer 215. Thereby, the magnetic field of the high magnetic flux density layer 152 can be effectively applied to the free layer 215.

  From the viewpoint of the characteristics of the magnetoresistive sensor 112, it is preferable that the slope of the side end of the magnetoresistive sensor 112 is steep. Specifically, the inclination angle (ψ in FIG. 3A) of the side end portion of the free layer 215 is preferably 45 ° or more, and more preferably 65 ° or more.

  In FIG. 3A, each of the high coercive force layer 151 and the high magnetic flux density layer 152 is a single layer. In FIG. 3B, the high magnetic flux density layer 152 is composed of a plurality of layers stacked in the vertical direction, and the high coercive force layer 151 is a single layer. In FIG. 3C, each of the high coercive force layer 151 and the high magnetic flux density layer 152 is composed of a plurality of layers stacked in the vertical direction. The high coercive force layer 151 may be composed of a plurality of layers stacked in the vertical direction, and the high magnetic flux density layer 152 may be a single layer. Each layer constituting the multilayer film is preferably 2 nm or less. By forming the high coercive force layer 151 or the high magnetic flux density layer 152 in a multilayer structure, the high coercive force layer 151 or the high magnetic flux density layer 152 suitable for each magnetic characteristic can be formed.

  As shown in FIGS. 3A to 3C, in the read head 11 in which the fixed layer 213, the nonmagnetic intermediate layer 214, and the free layer 215 are sequentially laminated from the lower layer side, the lower hard magnetic layer 151 is a high coercive force layer. It is preferable that This is because when the height position of the high magnetic flux density layer is matched with the free layer 215, more space for stacking exists on the lower layer side than on the upper layer side. In the magnetoresistive sensor 112 in this stacking order, only the sense cap layer 216 exists above the free layer 215, but a plurality of layers such as a fixed layer 213 and a nonmagnetic intermediate layer 214 exist below the free layer 215. There is a layer. Therefore, by setting the high magnetic flux density layer as the upper layer and the high coercive force layer as the lower layer, the high magnetic flux density layer is aligned with the free layer 215, and the thicknesses of the high magnetic flux density layer and the high magnetic flux density layer are set to desired values. Can be adjusted. Note that when the stacking order of the magnetoresistive sensor 112 is reversed, the positional relationship between the high magnetic flux density layer and the high coercive force layer is also reversed.

  4A to 4C show examples of the structure of a preferable hard bias film 115 in the vicinity of the magnetoresistive sensor 112. FIG. FIG. 4D shows a comparative example for these preferable structures. The upper hard magnetic layer 152 is a high magnetic flux density layer, and the lower hard magnetic layer 151 is a high coercive force layer. In the example where the side etching is not performed in FIG. 4D, the high coercive force layer 151 exists between the end surface on the magnetoresistive sensor 112 side and the high magnetic flux density layer 152 in the film surface. Further, the tips of the high coercive force layer 151 and the high magnetic flux density layer 152 on the side of the magnetoresistive sensor 112 protrude upward, and their upper surfaces are not flat. On the other hand, in each of the structures shown in FIGS. 4A to 4C that are side-etched, a high coercive force layer is provided between the front end surface of the magnetoresistive sensor 112 and the end surface on the magnetoresistive sensor 112 side of the high magnetic flux density layer 152. 151 does not exist. In the vicinity of the magnetoresistive sensor 112, the upper surfaces of the high coercive force layer 151 and the high magnetic flux density layer 152 are flat.

  This difference in structure causes a difference in applied magnetic field strength to the free layer 215. FIGS. 5A to 5C schematically show fluxes from the hard bias film 115 having different structures. 5A shows a preferred hard bias film shape, and FIGS. 5B and 5C show hard bias film shapes as comparative examples, respectively. FIG. 5C corresponds to FIG.

  As shown in FIG. 5B, when the hard bias film 115 is thick in the vicinity of the free layer 215, a lot of flux flows to the upper shield 113 instead of the free layer 215. As shown in FIG. 5C, when the hard bias film 115 protrudes toward the upper shield 113 at the tip of the free layer 215 side, the flux from the protruding portion is not the free layer 215 but the upper shield 113. And flow. On the other hand, in the preferable hard bias film shape shown in FIG. 5A, escape of these fluxes can be suppressed, and the magnetic field applied to the free layer 215 can be strengthened.

  4A to 4C, in order to increase the magnetic field strength from the high magnetic flux density layer 152 to the free layer 215, the high magnetic flux density layer 152 is preferably close to the free layer 215. When the high coercivity layer 151 does not exist between the end of the high magnetic flux density layer 152 and the end of the free layer 215 in the in-plane direction as shown in FIGS. The distance between the ends of the layer 215 is smaller. For this reason, the magnetic field applied to the free layer 215 is strengthened. A hard bias base film 116 exists between the high coercive force layer 151 and the junction insulating film 118, and the interval between the high magnetic flux density layer 152 and the magnetoresistive sensor 112 side end surface is the same as the high coercive force layer 151 and the magnetic field. It is smaller than the distance between the resistance sensor 112 side end surface.

  Further, in the proximity side-etched structure of FIG. 4B, the interval between the high magnetic flux density layer 152 and the free layer 215 can be further reduced by making a part of the junction insulating film 118 thinner. Alternatively, in the contact side etch structure of FIG. 4C, the junction insulating film 118 between the free layer 215 and the high magnetic flux density layer 152 is removed, and they are directly contacted. The interval between the free layer 215 and the high magnetic flux density layer 152 becomes 0, and the applied magnetic field strength can be maximized.

  2 will be described with reference to the flowchart of FIG. 6 and the process diagrams of FIGS. 7A to 7C. The process diagrams of FIGS. 7A to 7C show the structure near the right side of the magnetoresistive sensor 112, but the structure is the same on the left side. First, a multilayer film constituting the magnetoresistive sensor 112 is deposited by sputtering (S11). Thereafter, as shown in FIG. 7A (I), a resist layer 52 is formed by resist application and patterning (S12). As shown in FIG. 7A (II), the track width of the magnetoresistive sensor 112 is formed by etching using ion beam etching (IBE: also called ion milling) (S13). By this etching, the sensor cap film 216 to the sensor underlayer 211 are etched.

  Thereafter, a junction end oxidation process (S14) is performed as necessary, and then a junction insulating film 118 is deposited as shown in FIG. 7A (III) (S15). Further, as shown in FIG. 7B (IV), the hard bias base film 116 and the lower hard magnetic layer 151 constituting a part of the hard bias film 115 are attached (S16). In this embodiment, the junction insulating film 118 and the lower hard magnetic layer 151 are attached by ion beam deposition (IBD).

  Thereafter, as shown in FIG. 7B (V), the hard bias underlayer film 116 and a portion of the lower hard magnetic layer 151 are removed by IBE (S17). Specifically, the portion of the lower hard magnetic layer 151 protruding above the upper surface parallel to the film surface of the magnetoresistive sensor 112 is removed. As a result, a part of the upper side of the junction insulating film 118 is exposed beside the magnetoresistive sensor 112. Further, the upper surface of the lower hard magnetic layer 151 and the exposed surface (tip surface) of the hard bias underlayer 116 are flat in the vicinity of the magnetoresistive sensor 112.

  Next, as shown in FIG. 7B (VI), it adheres to the upper hard magnetic layer 152 constituting a part of the hard bias film 115 (S18). In this embodiment, the upper hard magnetic layer 152 is attached by IBD. Further, as shown in FIG. 7C (VII), a part of the upper hard magnetic layer 152 is removed by IBE (S19). Specifically, the portion of the upper hard magnetic layer 152 protruding above the upper surface parallel to the film surface of the magnetoresistive sensor 112 is removed. Thereby, the upper surface of the upper hard magnetic layer 152 becomes flat in the vicinity of the magnetoresistive sensor 112.

  Thereafter, as shown in FIG. 7C (VIII), a hard bias cap film 117 is deposited by IBD (S20). Further, as shown in FIG. 7C (IX), a part of the hard bias cap film 117 is removed by ion milling (S21). Specifically, the portion of the hard bias cap film 117 protruding above the upper surface parallel to the film surface of the magnetoresistive sensor 112 is removed. As a result, the upper surface of the hard bias cap film 117 becomes flat. Finally, the resist layer 52 is peeled off by lift-off (S22).

  In the manufacturing process of the read head 11, the hard bias film 115 and the hard bias cap film 117 are preferably formed continuously in the same vacuum chamber. By mounting the IBD / IBE coupling device in the chamber, the lower hard magnetic layer 151, the upper hard magnetic layer 152, and the hard bias cap film 117 can be continuously formed in a vacuum.

  In this embodiment, as described above, the magnetoresistive sensor 112 track width structure and the hard bias film 115 are formed by IBE and IBD. In particular, in the manufacture of the read head 11 of this embodiment, the pulse IBE and the pulse IBD are applied to the formation of these slope shapes. Hereinafter, the pulse IBE and the pulse IBD will be described in detail.

  FIG. 8A is an overview of the pulse IBE. The rectangles on the substrate 51 indicate resists 52 that are patterned corresponding to the read heads. In this IBE, an Ar ion beam is incident on the substrate in a state where the substrate is tilted, and the substrate 51 is rotated with its normal direction as a rotation axis. In the conventional track width forming process, the IBE always irradiates the substrate 51 with an Ar ion beam while rotating the substrate 51. However, in this type of IBE, only within a predetermined substrate rotation angle range set in advance. The substrate 51 is irradiated with an Ar ion beam.

  In the example of FIG. 8A, the incident angle of the Ar ion beam is inclined with respect to the normal direction of the substrate 51, and the inclination angle is α. The substrate 51 is uniformly rotated at a substantially constant angular velocity about the normal direction. As a characteristic point of this IBE, while the substrate 51 is rotating, the Ar ion beam does not always enter the substrate 51 but intermittently. FIG. 8B schematically shows this state. Specifically, the substrate is rotated at an inclination angle α. The resist is formed in a vertical contrast direction. Only when the angle of the substrate rotation direction is in the angle range of β around the angular position γ, the Ar ion beam is generated and incident on the substrate.

  The incident angle of the Ar ion beam with respect to the normal direction of the substrate is constant. However, with respect to the incident direction of the Ar ion beam projected onto the substrate surface, the incident direction is limited to a certain selected angle range with respect to the resist 52 (the magnetoresistive sensor 121). Accordingly, the incident angle can be controlled with respect to the slope of the side edge of the magnetoresistive sensor 112 of the Ar ion beam, and the etched shape of the slope and the hard bias film 115 of the side edge of the magnetoresistive sensor 112 are controlled. The removal of the side end on the magnetoresistive sensor 112 can be controlled with high accuracy. Alternatively, by appropriately selecting the incident angle of a part of the Ar ion beam, it is possible to reduce etching damage while minimizing reattachment to the slope.

  FIG. 9A schematically shows a relative change in the incident direction of the Ar ion beam with respect to the substrate 51. FIG. 9B schematically shows the incident direction of the Ar ion beam with respect to the side end face of the magnetoresistive sensor 112 (hard bias film 115 side end). While the substrate 51 is rotating, the incident angle α of the Ar ion beam with respect to the normal direction of the substrate 51 is constant. Therefore, as shown in FIG. 9A, the incident direction of the Ar ion beam including the state where it is not actually incident is relatively old when viewed from the substrate 51 and centered on the normal direction of the substrate 51. Perform differential exercise. When the incident direction is projected onto the substrate surface, the incident angle range in the in-plane direction is limited to a specific range.

  In this IBE, as shown in FIG. 9A, Ar ion particles, which are etching particles, are incident in a selected angle range having an incident direction that rotates within the projected substrate surface. It is important to select a symmetrical angle range in the vertical and horizontal directions in FIG. 8B and perform etching in the vicinity of the photoresist 52 symmetrically.

  FIG. 8B and FIG. 9A show an example of two-fold symmetry. The angle range of each incidence is symmetric in the vertical and horizontal directions in FIG. That is, the Ar ion beam is incident four times intermittently around the photoresist 52 (the magnetoresistive sensor 112). The sweep angle range β at each incidence is the same (incident angle range where incident is continuously performed), and the angle γ between each incident center angle (incident direction at the center during the sweep) and the track width direction is the same. It is. In other words, Ar ion beam incidence is skipped in a specific angle range centered on the track width direction and in a specific angle range centered on a direction perpendicular to the track width direction.

  There are several methods for limiting the incident angle range of the Ar ion beam. For example, 1) Etching is performed while controlling the rotation direction of the substrate and reciprocatingly oscillating, or 2) Opening / closing the shutter when the substrate rotation angle reaches the required incident angle, or 3) The substrate at the required incident angle. The incident timing of the Ar ion beam can be controlled, for example, by slowing the rotation speed when the rotation angle comes so as to effectively etch only at a certain incident angle.

  However, as described above, it is more rational and preferable to control the incident angle control of the Ar ion beam in the substrate rotation direction than to control it mechanically. Also, the problem of redeposition may remain when trying to control mechanically. That is, while the substrate is tilted and rotated, an ion beam is generated from the ion gun only when the substrate is within the required angle range of the particle incident direction, and etching is performed by a pulsed ion beam synchronized with the rotation of the substrate. Is preferred. The ion beam incidence timing can be easily controlled by electrically controlling the acceleration voltage of the ion gun.

  FIG. 10A illustrates a change in acceleration voltage corresponding to the examples of FIG. 8B and FIG. 9A. In this example, four intermittent Ar ion beams are incident, so the acceleration voltage shows four pulses with respect to the angle of the horizontal axis. The angle indicates the angle of the substrate 51, that is, the angle of the incident direction of the Ar ion beam projected onto the substrate 51, and 0 ° is the direction along the side end surface of the magnetoresistive sensor 112, that is, in FIG. The vertical direction is a direction perpendicular to the ABS surface. Each pulse waveform is symmetric about 180 °. Also, the two pulse waveforms between 0 ° and 180 ° are symmetrical around 90 °, and the two pulse waveforms between 180 ° and 360 ° (0 °) are around 270 °. It is symmetrical. 90 ° and 270 ° correspond to the track width direction when the incident direction of the Ar ion beam is projected onto the substrate 51. FIG. 10B shows an example of an acceleration voltage waveform corresponding to a single Ar ion beam incidence. The rising and falling slopes are in a condition range in which the Ar ion beam can be stably generated. Set the optimum value by design.

  FIG. 11A shows an example of etching (S 13) of the magnetoresistive sensor 112 covered with the photoresist 52. The magnetoresistive sensor 112 is covered with a patterned photoresist 52, and a portion exposed from the photoresist 52 is etched by an Ar ion beam. FIG. 11A shows the range of the incident direction in which the Ar ion beam changes. As described above, the Ar ion beam is incident symmetrically with respect to the substrate surface vertically and horizontally. FIG. 11B shows the change in the Ar ion beam incident direction and the corresponding acceleration voltage when viewed from the top surface of the substrate. Specifically, FIG. 11B shows the incident direction of the two-fold symmetric Ar ion beam and the acceleration voltage waveform corresponding to the incident direction.

  In FIG. 11B, the 12 o'clock direction of the circle indicating the incident direction corresponds to 0 ° in the waveform graph. The incident direction changes, for example, clockwise, and the angle of the waveform diagram with respect to each direction increases accordingly. In the 2-fold symmetry, Ar ion beam irradiation is performed twice on each of the left and right sides of the magnetoresistive sensor 112 in the track width direction. As shown in FIG. 11A, when the Ar ion beam is incident from the right side of the magnetoresistive sensor 112, the entire region on the right side of the magnetoresistive sensor 112 is exposed to the Ar ion beam. The portion becomes a shadow of the photoresist 52, and the Ar ion beam does not enter there. Similarly, when the Ar ion beam is incident from the left side of the magnetoresistive sensor 112, the entire left region of the magnetoresistive sensor 112 is exposed to the Ar ion beam, but a part of the right side becomes the shadow of the photoresist 52 and Ar The ion beam is not incident. Since the incident direction of the Ar ion beam is bilaterally symmetric, the region where the Ar ion beam is etched is also bilaterally symmetric.

  As the Ar ion beam incident direction approaches the vertical direction of FIG. 11B, that is, 0 ° and 180 °, the shadowed portion on the opposite side of the photoresist 52 becomes smaller. Accordingly, the outer width (OUTER WIDTH) is determined at an angular position where the incident direction is closest to the track width direction (90 ° and 270 °) within the angle range in which the Ar ion beam is actually incident. Further, the inner width (INNER WIDTH) is determined at the angular position where the Ar ion beam incident direction is farthest from the track width direction (closest to 0 ° and 180 °).

  Here, the change in the etching state with respect to the change in the Ar ion beam incident direction due to the rotation of the substrate 51 will be described. FIG. 12A schematically shows the incident angle of the Ar ion beam at the end portion on the magnetoresistive sensor 112 side. The Ar ion beam is incident with an inclination with respect to the normal direction of each surface. When the incident direction of the Ar ion beam with respect to the substrate 51 changes, the incident angle with respect to the surface of the end portion on the magnetoresistive sensor 112 side changes. Etching damage to each layer varies depending on the incident angle of the Ar ion beam.

  Compared to the case where an Ar ion beam is incident perpendicularly to the layer surface (incidence angle 0 °) as shown in FIG. 12B, it is inclined with respect to the layer surface as shown in FIG. (Corresponding to an increase in incident angle) The depth of etching damage can be reduced when the Ar ion beam is incident. In the etching process of the magnetoresistive sensor 112, it is important to reduce etching damage at the side edge. This is because if the etching / damage layer is deep, a shunt current flows through the layer, and the magnetoresistive sensor 112 does not function normally. Therefore, it is particularly important to reduce etching damage at the end of the nonmagnetic intermediate layer 214 side.

  In the IBE, in forming the end shape of the magnetoresistive sensor 112, the incident angle of the Ar ion beam to the side end portion of the magnetoresistive sensor 112 is inclined with respect to the track width direction. Specifically, as shown in FIG. 8B, the incident direction of the Ar ion beam is limited to an incident angle in the angle range β with the inclination angle γ as the center with respect to the track width direction. Incidence in the track width direction has the smallest incident angle with respect to the normal direction of the side end surface, and the incident angle on the side end surface increases with distance from the direction. From the viewpoint of etching damage, it is preferable to increase the incident angle, that is, to increase β and decrease β.

  However, if the incident angle is increased too much, the etching rate is greatly reduced and the angle of the side end portion becomes smaller, that is, the inclination of the side end portion becomes gentle. When the etching energy is low, the etching rate decreases, and the etching rate varies depending on the incident angle. Accordingly, by selecting the optimum etching angle and conditions for the inclination angle of the side end portion of the magnetoresistive sensor 112, the ratio of the etching rate to the side end inclination angle and the etching rate in the normal direction of the substrate surface can be obtained. It becomes possible to select. As a result, the inclination angle of the side end can be improved while reducing etching damage. In the actual manufacturing process, the etching energy and the angle range of the incident direction of the ion beam are determined so that the end on the side of the magnetoresistive sensor 112 is steep and the etching damage is reduced.

  Here, when IBE is based only on the above method, it is considered that the etching time becomes long and the throughput decreases. Therefore, it is preferable to change the incident angle range of the Ar ion beam during the etching process. As a result, the final etching damage can be reduced and the throughput can be increased. FIG. 13 shows a preferred example of a method for controlling the incident angle range of the Ar ion beam in the magnetoresistive sensor 112 etching step (S13). The etching process is composed of three processes: an initial shape forming process, an end shape forming process, and a damaged layer removing process.

  The circle in each step indicates rotation in the incident direction with respect to the substrate surface, and the radius increases as the inclination angle α with respect to the substrate normal increases. In the initial shape forming process, an Ar ion beam is incident from all directions according to the rotation of the substrate. In addition, the inclination angle α with respect to the substrate normal is set to be smaller than in the subsequent steps. Subsequently, the inclination angle α with respect to the substrate normal is increased to perform the edge shape forming step. In this step, the Ar ion beam is incident on the substrate only in a specific angle range in the direction of rotation with respect to the substrate surface. In contrast to the two-fold symmetry Ar ion beam incidence in the subsequent damage layer removal step, this step is one-time symmetry Ar ion beam incidence.

  That is, an Ar ion beam is incident in a specific angle range symmetric about the track width direction from the left and right directions in the track width direction (left and right direction in FIG. 13, 90 ° and 270 ° in FIG. 11B). To do. Then, Ar ion beam incidence is skipped in a predetermined angle range centering on a direction (vertical direction in FIG. 13, 0 ° and 180 ° in FIG. 11B) perpendicular to the track width direction on the substrate surface.

  In this step, the end shape of the magnetoresistive sensor 112 is determined. As described with reference to FIGS. 11A and 11B, the outer width (OUTER WIDTH) is defined at the incidence in the track width direction, and the inner width ( INNER WIDTH). In this process, since the Ar ion beam is incident within an angle range centering on the track width direction, the Ar ion beam incident angle to the end of the magnetoresistive sensor 112 is reduced, and the etching damage depth is increased. Become. However, the etching time per rotation of the substrate is long, and by including a specific incident angle, the etching rate can be increased and the processing time can be shortened. In this step, the removal of the redeposition film by etching is also performed.

  Subsequently, the damage layer removing step is performed by further increasing the inclination angle α with respect to the substrate normal. This process is a two-fold Ar ion beam incidence as in the method described with reference to FIGS. The damage layer in the edge shape forming step is generally about 2 nm. Therefore, the final etching damage at the end of the magnetoresistive sensor 112 can be reduced by etching this damaged layer with an Ar ion beam having a large incident angle with small etching damage.

  Here, the inclination angle α with respect to the substrate normal and the incident angles (β and γ) with respect to the substrate normal so that the outer width (INCIDENT OUTER WIDTH) and the inner width (INCIDENT INNER WIDTH) are the same as in the edge shape forming process. Set. This removes the etching / damage layer at the end of the magnetoresistive sensor 112 and suppresses the change in the step shape between the sensor underlayer 211 and the antiferromagnetic film 212. Although the etching of the end portion of the magnetoresistive sensor 112 has been mainly described above, the same process can be applied to the etching of the side end portion of the hard bias film 115.

  Hereinafter, the attaching process (S15, S17) of the hard bias film 115 in this embodiment will be described in detail. FIG. 14A shows a schematic diagram of an ion beam sputtering method used in the IBD of this embodiment. In the ion beam sputtering method, the incident direction of the ion beam to the target 61 (angle between the target normal and the incident direction) and the incident direction α of the particles sputtered from the target 61 to the substrate are controlled. Then, control of the surroundings of the formed film and the end shape of the photoresist is performed. In addition, the substrate rotates uniformly during film formation.

  As a film forming method, similarly to the etching, the sputtered particles are made incident at a predetermined angle with a rotation direction angle in the substrate surface. In addition, a symmetrical angle is selected with respect to the photoresist direction with respect to the left and right and the top and bottom, and the film attachment in the vicinity of the photoresist is made symmetrical. As in the case of etching, several methods are conceivable as a method for forming a film by defining the direction of the incident particles with respect to the rotation direction of the substrate. In the attaching step, it is preferable to adopt the same method as that used in etching. That is, the ion beam is generated from the ion gun only when the substrate comes within the required angle range of the particle incident direction, and the film is formed by the pulsed ion beam synchronized with the rotation of the substrate.

  FIG. 14B illustrates the incident direction of sputtered particles as viewed from the substrate 51. By controlling the particle angle α incident on the substrate from the target and the angle β in the substrate rotation plane, the particle incident position can be controlled, and at the same time, the shape of the formed film in the vicinity of the photoresist can be controlled. FIG. 14B shows an example of one-time symmetrical sputter particle incidence.

  FIG. 15A schematically shows the state of the adhesion process of the lower hard magnetic layer 151. FIG. 15B shows the incident direction of sputtered particles in the substrate surface, and FIG. 15C shows the acceleration voltage of the corresponding ion beam. As for the incidence of sputtered particles, the same explanation as the incidence of etching particles described with reference to FIG. One important point is that the lower hard magnetic layer 151 is deposited so as to match the etching shape on the lower layer side. By attaching the lower hard magnetic layer 151 so as to coincide with the step on the lower layer side, the upper surface of the lower hard magnetic layer 151 can be flattened.

  As shown in FIGS. 15A and 15B, the lower hard magnetic layer 151 having a large outer thickness is formed by matching the outer width (INCIDENT OUTER WIDTH) and the inner width (INCIDENT INNER WIDTH) with the step on the lower layer side. Adhere. The lower hard magnetic layer 151 is attached so that the ratio between the outer film thickness and the inner film thickness of the lower hard magnetic layer 151 becomes a desired value (for example, 2). The thin region of the lower hard magnetic layer 151 is limited to the inner width (INCIDENT INNER WIDTH), and the other regions are formed to have a film thickness twice as large as that in the vicinity of the magnetoresistive sensor 112.

  FIG. 16 shows how the incident direction of sputtered particles is controlled in the adhesion of the hard bias underlayer film 116 and the lower hard magnetic layer 151. The meaning of each figure is the same as in FIG. The hard bias undercoat film 116 is attached to the sputtered particles from all directions. The hard bias base film controls the crystal state of the hard bias film and is thin. After the hard bias underlayer film 116 is formed, the lower hard magnetic layer 151 is deposited by one-time symmetrical sputter particle incidence as described above.

  In the adhesion of the lower hard magnetic layer 151, the incident angle α of the sputtered particles in the normal direction of the substrate and the angle range in the substrate plane are selected according to the film shape. By this adhesion method, magnetic anisotropy in the track width direction can be imparted to the hard bias film 115. That is, by adding magnetic anisotropy in the track width direction, the magnetostatic characteristics in the track width direction can be improved, and the characteristics of the hard bias film can be improved. It should be noted that two-fold symmetric sputter particle incidence may be selected for the sputter particle adhesion. As described above, in the adhesion of the lower hard magnetic layer 151, by selecting the incident direction of the sputtered particles, their shapes can be controlled according to the design.

  After the lower hard magnetic layer 151 is attached, the protrusion on the magnetoresistive sensor 112 side of the lower hard magnetic layer 151 is removed by pulse IBE. Further, the upper hard magnetic layer 152 is formed by the same method as the adhesion and etching of the lower hard magnetic layer 151. Thereby, the shape and film thickness of the upper hard magnetic layer 152 can be highly controlled.

  As mentioned above, although this invention was demonstrated taking preferable embodiment as an example, this invention is not limited to said embodiment. A person skilled in the art can easily change, add, and convert each element of the above-described embodiment within the scope of the present invention. For example, the stacking order of the layers of the magnetoresistive sensor can be reversed. The hard bias film can be formed of three or more hard magnetic layers having different magnetic characteristics.

It is sectional drawing which shows typically the structure of the magnetic head which concerns on this embodiment. It is sectional drawing which shows typically the structure of the read head which concerns on this embodiment. It is a figure which shows typically the preferable example of the hard bias film | membrane structure of the read head concerning this embodiment. It is a figure which shows typically the preferable example of the hard bias film structure of the read head which concerns on this embodiment, and a comparative example. It is a figure which shows typically the flux of the hard bias film | membrane structure which concerns on this embodiment, and a comparative example. 5 is a flowchart showing a manufacturing process of the read head according to the embodiment. It is a figure which shows typically the manufacturing process of the read head concerning this embodiment. It is a figure which shows typically the manufacturing process of the read head concerning this embodiment. It is a figure which shows typically the manufacturing process of the read head concerning this embodiment. FIG. 10 is a diagram schematically showing an etching method in the manufacturing process of the read head according to the embodiment. It is a figure which shows typically the incident direction of Ar ion beam, and the mode of the etching in the etching process which concerns on this embodiment. In the etching process which concerns on this embodiment, it is a figure which shows an example of the waveform of the acceleration voltage of Ar ion beam. It is a figure which shows typically the incident direction of Ar ion beam, and the mode of the etching in the etching process which concerns on this embodiment. In the etching process which concerns on this embodiment, it is a figure which shows the change of the etching state by the incident angle of Ar ion beam. It is a figure which shows typically the mode of the incident direction change of Ar ion beam in the etching process which concerns on this embodiment. It is a figure which shows typically the method of sputter adhesion in the manufacturing process of the read head concerning this embodiment. It is a figure which shows typically the incident direction of a sputtered particle, and the state of the lower layer hard magnetic film formed in the sputter adhesion which concerns on this embodiment. It is a figure which shows typically the mode of the incident direction change of the sputtered particle in the hard bias base film and lower hard magnetic layer adhesion process concerning this embodiment. It is sectional drawing which shows typically the structure of the read head concerning a prior art. It is a flowchart which shows the manufacturing process of the read head concerning a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetic head, 2 Slider, 3 Magnetic disk, 11 Read head 12 Write head, 16 Junction insulating film, 51 Substrate, 52 Resist layer 111 Lower shield, 112 Magnetoresistive sensor, 113 Upper shield 115 Hard bias film, 116 Hard Bias underlayer 117 Hard bias cap film 121 Thin film coil 122 Recording magnetic pole 123 Insulator 151 Lower hard magnetic layer 152 Upper hard magnetic layer 211 Sensor underlayer 212 Antiferromagnetic film 213 Fixed layer 214 Nonmagnetic intermediate Layer, 215 free layer, 216 sensor cap film

Claims (10)

A magnetoresistive sensor film having a free layer, a fixed layer, and a nonmagnetic intermediate layer between the free layer and the fixed layer, and formed on both sides of the magnetoresistive sensor film, the free layer A hard bias film made of a hard magnetic material for stabilizing the magnetization state of the magnetoresistive sensor film, and an insulating film disposed on both sides of the magnetoresistive sensor film in order to flow a detection current in the stacking direction of the magnetoresistive sensor film, In a magnetic read head having an upper shield and a lower shield formed so as to sandwich the magnetoresistive sensor film in the vertical direction,
Each of the hard bias films has a stacked first hard magnetic layer and second hard magnetic layer,
The saturation magnetic flux density and the residual magnetic flux density of the first hard magnetic layer are made of a material larger than that of the second hard magnetic layer,
And,
The coercive force of the second hard magnetic layer is made of a material larger than the coercive force of the first hard magnetic layer,
The upper shield has a flat portion that overlaps with the free layer, and the width of the flat portion is equal to or greater than the width of the free layer,
CPP magnetic read head. At least a part of the first hard magnetic layer and at least a part of the free layer have the same height position,
The CPP magnetic read head of claim 1. The height position of the lower surface of the first hard magnetic layer is coincident with the height position of the lower surface of the free layer,
The CPP magnetic read head of claim 2. The pinned layer, the nonmagnetic intermediate layer, and the free layer are sequentially stacked from the bottom to the top,
The first hard magnetic layer is formed above the second hard magnetic layer,
The CPP magnetic read head of claim 2. The distance between the first hard magnetic layer end, the magnetoresistive sensor film end, and the free layer end is
The distance between the end of the second hard magnetic layer and the end of the magnetoresistive sensor film, the end of the free layer is smaller,
The CPP magnetic read head of claim 1. The thickness of each of the first hard magnetic layer and the second hard magnetic layer is substantially equal to the inner film thickness at a position spaced from the side edge of the free layer between the lower shield and the upper shield. 2 times,
The width of the flat portion of the upper shield is substantially equal to a value obtained by adding a value of twice the interval between the lower shield and the upper shield and the width of the free layer,
The CPP magnetic read head of claim 1. The first hard magnetic layer and the second hard magnetic layer have a single layer structure or a multilayer structure formed of an alloy containing Co as a main component,
The residual magnetic flux density of the first hard magnetic layer is 1.0 T or more,
The CPP magnetic read head of claim 1. Forming a magnetoresistive sensor film having a free layer, a fixed layer, and a nonmagnetic intermediate layer between the free layer and the fixed layer;
In order to flow a detection current in the stacking direction of the magnetoresistive sensor film, an insulating film is formed on both ends of the magnetoresistive sensor film,
In the vacuum chamber, on the magnetoresistive sensor film for the insulating film, a lower hard magnetic layer constituting a part of the hard bias film is attached by ion beam deposition,
In the vacuum chamber, a part of the lower hard magnetic layer on the magnetoresistive sensor film side end side is removed by ion beam etching,
In the vacuum chamber, an upper hard magnetic layer constituting a part of the hard bias film is deposited on the lower hard magnetic layer by ion beam deposition.
One of the upper hard magnetic layer and the lower hard magnetic layer has a larger saturation magnetic flux density and residual magnetic flux density and a smaller coercive force than the other,
In the vacuum chamber, a part of the magnetoresistive sensor film side end side of the upper hard magnetic layer is removed by ion beam etching,
A hard bias cap film is formed on the upper hard magnetic layer in the vacuum chamber.
CPP magnetic read head manufacturing method. The magnetoresistive sensor film is formed using ion beam deposition and ion beam etching, and the ion beam in forming the magnetoresistive sensor film, the lower hard magnetic layer, and the upper hard magnetic layer. In the deposition and the ion beam etching, the ion beam and the sputtered particle beam are incident on the inclined surface while changing the incident angle, and the incident angle is limited to a preset angle range. did,
A method of manufacturing a CPP magnetic read head according to claim 8. The first hard bias film disposed in the vicinity of the magnetoresistive sensor element is formed by a device in which an ion beam deposition device and an ion beam etching device are coupled through a single vacuum device. did,
9. The CPP magnetic read head and manufacturing method according to claim 8.

Images