JP2009259355A - Cpp magnetic read head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a CPP (Current Perpendicular Plane) magnetic read head having superior characteristics. <P>SOLUTION: As an embodiment, the CPP read head 11 has first hard bias films 151 on both right and left sides of a magneto-resistive sensor 112, and further has a second hard bias film 152 laminated in contact with the first hard bias films. The second hard bias film is continuous in an in-plane direction of the magneto-resistive sensor, and formed even on the magneto-resistive sensor. Magnetization of the first hard bias films is stabilized by the second hard bias film, and reduced in film thickness to more flatten an upper shield 113 near the magneto-resistive sensor. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a CPP (Current Perpendicular Plane) magnetic read head, and more particularly to a hard bias film structure in a CPP magnetic read head.

  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. 7A is a sectional view schematically showing the structure and configuration of the CPP read head 61, and FIG. 7B is a partially enlarged view thereof. The magnetoresistive sensor 612 is between the lower shield 611 and the upper shield 613. The lower shield 611 and the upper shield 613 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 612. An upper magnetic isolation film 614 made of a conductor is formed below the upper shield 613.

  The magnetoresistive sensor 612 includes a sensor base layer 261, an antiferromagnetic film 262, a fixed layer 263, a nonmagnetic intermediate layer 264, a free layer 265, and a sensor cap film 266 that are sequentially stacked from the lower layer side. An exchange interaction with the antiferromagnetic film 262 acts on the fixed layer 263, and its magnetization direction is fixed. When the read head 61 is a TMR head, the nonmagnetic intermediate layer 264 is formed of an insulator such as alumina (AL2O3) or magnesium oxide (MgO). When using CPP-GMR, the nonmagnetic intermediate layer 264 is Cu It is formed using a non-magnetic conductor such as an alloy. The track width of the free layer 265 is indicated by Twf.

  The magnetoresistive head operates by utilizing the fact that the resistance is changed by the change in the magnetization direction of the free layer 265 relative to the magnetization direction of the fixed layer 263. That is, when the magnetization direction of the free layer 265 is changed by the information magnetic field from the magnetic disk with respect to the magnetization direction of the fixed layer 263, the resistance value (current value) of the magnetoresistive sensor 612 is changed. The read head 61 can detect a narrowed external information magnetic field by detecting the resistance value (current value) of the magnetoresistive sensor 612.

Hard bias films 615 exist on the left and right sides of the magnetoresistive sensor element 612. A bias magnetic field from the hard bias film 615 is applied to the free layer 265 to act to make the free layer 265 a single magnetic domain, and stabilize the magnetization operation of the free layer. The hard bias film 615 is formed on the hard bias base film 616. A junction insulating film 617 is formed as a lower layer of the hard bias base film 616. The insulating film 617 exists between the hard bias base film 616, the lower shield film 611, and the magnetoresistive sensor 612, and prevents the detection current from flowing outside the magnetoresistive sensor 612.
JP 2006-173156 A

  In the generation of CPP-TMR / GMR heads with higher recording density, the free layer track width Twf is reduced and shielded in order to cope with increased TPI (Track Per Inch) and BPI (Bit Per Inch). It is necessary to narrow the gap Gs. Here, if the flattening width USFL of the upper shield 613 (shield interval Gs) with respect to the free layer track width Twf is not sufficient, the effect of the upper shield 613 is reduced at the end of the magnetoresistive sensor 612, and the reading spread width is increased. There is a problem to do. This problem is particularly noticeable in a read head having a narrowed track width Twf and shield interval Gs.

  Therefore, it is important to increase the flattening width USFL of the upper shield 613 on the magnetoresistive sensor 612 in the read head having the narrowed track width Twf and shield interval Gs. In order to increase the flattening width USFL of the upper shield 613, it is necessary to reduce the thickness of the hard bias film. However, when the hard bias film is thinned, the magnetic stability of the hard bias film is lowered and the hard bias magnetic field is reduced. For this reason, there is a problem in that the free layer is not sufficiently made into a single magnetic domain and exhibits a noisy and unstable magnetization operation.

  Therefore, a technique for increasing the magnetization stability of the hard bias film without increasing the film thickness of the hard bias film is desired for flattening the upper shield and stabilizing the magnetization operation of the free layer. Here, Patent Document 1 discloses a technique in which a pair of antiferromagnetic layers are formed on a hard bias layer via an enhancement layer made of a magnetic material in order to stabilize the magnetization of the hard bias layer. Yes. An exchange coupling magnetic field is generated between the antiferromagnetic layer and the enhancement layer, the magnetization direction of the enhancement layer is fixed in the track width direction, and the ferromagnetic coupling acts between the enhancement layer and the hard bias layer, and the hard layer The force for fixing the magnetization direction of the bias layer in the track width direction is increased.

  However, since the enhancement layer of Patent Document 1 is a soft magnetic layer whose magnetization direction is fixed by an antiferromagnetic layer, it is considered that the enhancement layer cannot exert a sufficient effect for stabilizing the magnetization of the hard bias film. Also, an antiferromagnetic layer and a soft magnetic layer are required for stabilizing the magnetization of the hard bias film. For this reason, there is a limit to reducing the combined thickness of the hard bias film and these layers, and it is difficult to increase the flattening width of the upper shield. Actually, in the above-mentioned Patent Document 1, the total thickness of the hard bias film and these layers is increased, which obstructs the flattening of the upper shield.

  Alternatively, the enhancement layer of Patent Document 1 is formed at a position overlapping the hard bias film, and is not formed on the sensor multilayer film. For this reason, it is difficult to planarize the upper shield in the vicinity of the sensor multilayer film, and unstable magnetization of the upper shield is transferred to the free layer, which may cause noise in the read signal.

  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 magnetoresistive film. A first hard made of a hard magnetic material, which is formed on both sides of the magnetoresistive sensor film, and is formed on both sides of the magnetoresistive sensor film so as to sandwich the sensor film in the vertical direction. A hard magnetic material formed between the bias film, the upper shield and the free layer, and between the first hard bias film and the upper shield, and in contact with the first hard bias film; And a second hard bias film. Thereby, the characteristics of the CPP magnetic read head can be improved.

The upper surface of the second hard bias film is preferably flat in the vicinity of junctions on both sides of the magnetoresistive sensor film. Thereby, the noise of the CPP magnetic read head can be reduced.
Preferably, the second hard bias film and the free layer are magnetically isolated. As a result, the undesirable magnetic influence on the free layer by the second hard bias film can be suppressed, and the characteristics of the CPP magnetic read head can be effectively improved.

  A base film for controlling the orientation of the second hard bias film is further formed between the free layer and the second hard bias film in contact with the lower surface of the second hard bias film. It is preferable. Thereby, the orientation of the second hard bias film can be effectively controlled. Furthermore, it is preferable that the base film is a Cr or Cr alloy film that is a (200) alignment film, and the second hard bias film is a Co alloy (100) C-axis in-plane alignment film. Thereby, a desired bias magnetic field can be more effectively applied to the free layer.

  A base film for controlling the orientation of the first hard bias film is further formed in contact with the lower surface of the first hard bias film, and the base film of the first hard bias film is (200). Preferably, the alignment film is Cr or a Cr alloy film, and the first hard bias film is a Co alloy (100) C-axis in-plane alignment film. Thereby, the orientation of the first hard bias film can be effectively controlled, and a desired bias magnetic field can be effectively applied to the free layer.

  The first hard bias film has a saturation magnetic flux density and a residual magnetic flux density larger than the second hard bias film, and the second hard bias film has a coercive force larger than that of the first hard bias film. Is preferred. Thereby, the bias magnetic field can be increased more effectively and the film thickness of the first hard bias film can be reduced more effectively.

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

  Hereinafter, specific embodiments of the present invention 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) read head in which a sense current flows in the stacking direction of the magnetoresistive sensor film (direction perpendicular to the film surface).

  The CPP read head of this embodiment has first hard bias films on both the left and right sides of the magnetoresistive sensor, and further has a second hard bias film laminated in contact with the first hard bias film. . The second hard bias film is continuous in the in-plane direction of the magnetoresistive sensor and is also formed on the magnetoresistive sensor. The magnetization of the first hard bias film can be stabilized by the second hard bias film, the film thickness of the first hard bias film can be reduced, and the upper shield can be flattened in the vicinity of the magnetoresistive sensor. .

  FIG. 1 is a cross-sectional view schematically showing the structure of a magnetic head 1 to which the CPP read head of the present invention can be applied. 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. The read head 11 receives magnetic data recorded on the magnetic disk 2 by a resistance value that changes according to the magnetic field from the magnetic disk 2. read out. The read head 11 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 detection 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).

  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 detection 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, and a sensor cap film 216, which are sequentially stacked from the lower layer side. It is a laminated multilayer film. Further, the magnetoresistive sensor 112 of this embodiment has a base film 217 of the second hard bias film as the uppermost layer. 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 formed of a nonmagnetic conductive material such as Ta. The base film 217 of the hard bias film will be described in detail later.

The read head 11 has junction insulating films 118 on both left and right ends (referred to as junctions) of the magnetoresistive sensor 112 so that a desired detection current flows in the magnetoresistive sensor 112. The junction insulating film 118 extends further outward from the end of the magnetoresistive sensor 112 and is made of, for example, Al ₂ O ₃ . 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 caused by magnetic domain inhomogeneity of the free layer 215 and stabilize its magnetic operation, a first hard bias film 151 as a magnetic domain control film is provided on the left and right sides of the magnetoresistive sensor 112. Exists. The first hard bias film 151 is made of a hard magnetic material. Typically, the first hard bias film 151 is made of a Co alloy, and is made of a CoCrPt alloy, a CoPt alloy, or the like.

  The bias magnetic field from the first 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 first hard bias films 115 on the left and right sides 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 first hard bias film 115. The film thickness of the flat portion of the first hard bias film 115 away from the junction of the magnetoresistive sensor 112 is typically about 10 nm.

  The first hard bias film 115 is formed on and in contact with the first hard bias base film 116. Preferably, the first hard bias underlayer film 116 has a two-layer structure. The upper layer of the base film controls the crystal state of the hard bias film 115. The lower layer of the base film is an amorphous layer, and controls the crystal state of the upper layer of the base film. In order to generate a uniform and strong bias magnetic field with little variation by the first hard bias film 115, it is important to control and adjust the polycrystalline orientation state of the Co alloy magnetic film.

  Here, the polycrystalline layer orientation of the Co alloy magnetic film as the first hard bias film 151 can be controlled by forming the upper layer of the base film from Cr or Cr alloy and adjusting and controlling the orientation state thereof. The first hard bias film 151 of the Co alloy is preferably a Co (100) C in-plane alignment film. Thereby, the C axis of the Co alloy is parallel to the surface of the free layer 215, and the magnetization of the first hard bias film 151 can be effectively applied to the free layer 215.

  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 (the lower layer of the base film). Only a specific orientation state of Cr and Co alloy can be realized on the layer of the magnetoresistive sensor film 112 which is a polycrystalline film having a face-centered cubic structure system. 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. The upper layer of the base film that is in contact with the first hard bias film 151 is made of Cr or a Cr alloy film, and the Cr or Cr alloy film is a (200) orientation film. 151 can be a Co alloy (100) C-axis in-plane alignment film.

  As a material for the amorphous underlayer, for example, Ni or Co is used as a base layer to contain an additive element. Preferably, Ni is used. Examples of the element to be added include P, Cr, Zr, Nb, Hf, and Ta. 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 CPP read head 11 of this embodiment has a second hard bias film 152 in addition to the first hard bias film 151. The second hard bias film 152 is between the upper shield 113 and the first hard bias film 151, and a hard bias cap film 117 is formed on the second hard bias film 115. The film thickness of the second hard bias film 115 is typically about 3 nm.

  The second hard bias film 152 is made of a hard magnetic material. The lower surface of the second hard bias film 152 is in contact with the upper surface of the first hard bias film 151, and an exchange interaction works between the second hard bias film 152 and the first hard bias film 151. The second hard bias film 152 exchange-coupled to the first hard bias film 151 stabilizes the magnetization of the first hard bias film 151, and the film thickness of the first hard bias film 151 is increased in the vicinity of the magnetoresistive sensor 112. Can be thinned.

  The second hard bias film 152 is formed as one continuous layer, and is in contact with the upper surfaces of the first hard bias films 151 on both the left and right sides. By forming the second hard bias film 152 in this way, the volume can be increased and the magnetic stability can be improved. The second hard bias film 152 is also present on the magnetoresistive sensor 112 between the left and right first hard bias films 151.

  By disposing the second hard bias film 152 between the free layer 215 and the upper shield 113, the noise of the read signal generated when the unstable magnetization of the upper shield 113 is transferred to the free layer 215 is reduced. Can do.

  Preferably, as shown in FIG. 2, the magnetoresistive sensor 112 is formed with a second hard bias base film 217 that is a base film of the second hard bias film 152. The upper surface of the second hard bias base film 217 is in contact with the lower surface of the second hard bias film 152. The second hard bias base film 217 has a function similar to that of the first hard bias base film 116. That is, the second hard bias base film 217 controls the crystal structure and orientation state of the second hard bias film 152.

  The second hard bias base film 217 is preferably formed of the same layer structure and material as the first hard bias base film 116. Specifically, the second hard bias base film 217 has a two-layer structure, and the upper layer in contact with the second hard bias film 152 is formed of Cr or a Cr alloy. Further, the Cr or Cr alloy film is preferably a (200) orientation film.

  As a result, the second hard bias film 152 made of Co alloy can be a Co alloy (100) C-axis in-plane alignment film. In this orientation, the C axis of the Co alloy is parallel to the surface of the free layer 215, and the magnetic flux of the second hard bias film 152 is prevented from deteriorating the characteristics of the magnetoresistive sensor 112 by disturbing the magnetization of the free layer 215. can do. The orientation of the upper layer of the second hard bias base film 217 made of Cr or a Cr alloy can be adjusted and controlled by an amorphous base film that is the base film (under the base film). This is the same as the first hard bias base film 116.

  As a preferred embodiment, the second hard bias film 152 shown in FIG. 2 is magnetically coupled to the first hard bias film 151, but is magnetically isolated from the free layer 215 in the magnetoresistive sensor 112. Yes. Specifically, the sensor cap film 216 or the second hard bias base film 217 exists between the second hard bias film 152 and the free layer 215.

  These are non-magnetic materials, and magnetically isolate the second hard bias film 152 from the free layer 215. By disconnecting the magnetic coupling between the second hard bias film 152 and the free layer 215 in this way, the magnetization direction of the free layer 215 is fixed by the second hard bias film 152, and the magnetic detection characteristics are impaired. Can be prevented.

  Preferably, the first hard bias film 151 is a high magnetic flux density layer, and the second hard bias film 152 is a high coercive force layer. Thereby, even if the first hard bias film 151 is thinned, a necessary bias magnetic field can be applied to the free layer 215 and the magnetization of the first hard bias film 151 can be effectively stabilized.

  Specifically, the first hard bias film 151 has a larger magnetic flux density than the second hard bias film 152, and further has a smaller coercivity than the second hard bias film 152. Both the residual magnetic flux density Br and the saturation magnetic flux density Bs of the first hard bias film 151 are larger than those of the second hard bias film 152. In general, a magnetic material exhibiting a large coercive force does not exhibit a high magnetic flux density. The high coercivity second hard bias film 152 stabilizes the magnetization of the high magnetic flux density first hard bias film 151.

  Preferably, the first hard bias film 151 is formed of a CoPtX alloy material. X is an element selected from Cr, Ta, W, Ti, V, Zr, Nb, Mo, and Rh. The first hard bias film 151 may include a plurality of elements. Preferably, the second coercive force second hard bias film 152 is made of a CoPtX alloy material. X is an element selected from Cr, Ta, W, Ti, V, Zr, Nb, Mo, and Rh. The second hard bias film 152 may include a plurality of elements.

  By thinning the first hard bias film 151 in the vicinity of the magnetoresistive sensor 112, the bias magnetic field to the free layer 215 can be controlled more effectively. By aligning the height position of the first hard bias film 151 with the free layer 215, the bias magnetic field applied to the free layer 215 can be localized and optimized.

  The side end face of the first hard bias film 151 faces the free layer 215 at the junction (side end face) of the magnetoresistive sensor 112. That is, the height position of at least a part of the first hard bias film 151 coincides with at least a part of the free layer 215. Typically, the thickness of the end face of the first hard bias film 151 is equal to or greater than the thickness of the end face of the free layer 215, and the entire area of the end face of the free layer 215 faces the end face of the first hard bias film 151. That is, the height positions of the upper and lower surfaces of the free layer 215 are in a region defined by the height positions of the upper and lower surfaces of the first hard bias film 151. Thereby, the strong magnetic field of the high magnetic flux density layer 152 can be effectively applied to the free layer 215.

  The upper surface of the second hard bias film 152 is preferably flat in the vicinity of the surface of the magnetoresistive sensor 112 and the junction, and is flat across the free layer track width Twf. The lower surface shape of the upper shield 113 is defined by the upper surface shape of the second hard bias film 152. The lower surface of the upper shield 113 is flat near the surface of the magnetoresistive sensor 112 and the junction, and over the free layer track width Twf, The lower surface of the upper shield 113 can be made flat. In the read head 11 of FIG. 2, the portions of the upper surface of the second hard bias film 152 and the lower surface of the upper shield 113 that overlap with the magnetoresistive sensor 112 are substantially flat.

  Furthermore, the flat width SHFL on the upper surface of the second hard bias film 152 and the flat width USFL on the lower surface of the upper shield 113 are preferably equal to or larger than the free layer track width Twf, and these flat widths are on the left and right sides of the Twf. It is preferable to spread. In FIG. 2, the flat portion of the second hard bias film 152 and the flat portion of the upper shield 113 extend to the left and right sides of the free layer 215.

  Preferably, the flat widths SHFL and USFL of the second hard bias film 152 and the upper shield have a sufficient dimension larger than the free layer track width Twf, specifically, the dimension of the free layer track width Twf + 2Gs. Preferably they are the same or higher. As a result, it is possible to improve output characteristics while suppressing reading bleeding at the end of the free layer 215.

  The second hard bias film 152 enables the first 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 can be reduced, and the upper shield 113 can be flattened at a position overlapping the magnetoresistive sensor 112 and in the vicinity of the magnetoresistive sensor 112.

  The first hard bias film 115 is preferably flat in the vicinity of the magnetoresistive sensor 112. As a result, a decrease in the bias magnetic field applied to the free layer 215 by the first hard bias film 115 can be suppressed. 3A and 3B schematically show fluxes from the first hard bias film 151 having different shapes.

  FIG. 3A schematically shows the flux in the conventional hard bias film shape, and FIG. 3B schematically shows the flux by the first hard bias film 151 of this embodiment. As shown in FIG. 3A, when the hard bias film 615 is thick in the vicinity of the free layer 215, a lot of flux flows to the upper shield 613 instead of the free layer 265. On the other hand, in the preferable hard bias film shape of this embodiment shown in FIG. 3B, escape of these fluxes can be suppressed, and the magnetic field applied to the free layer 215 can be strengthened.

  Regarding the flat width of the first hard bias film 151, the same idea as the flat width of the upper surface of the second hard bias film 152 can be applied. The upper surface of the first hard bias film 151 (the lower surface of the second hard bias film 152) is flat in the vicinity of the junction of the magnetoresistive sensor 112, and is preferably equal to or larger than the free layer track width Twf. It is preferable to spread on both the left and right sides than Twf. Furthermore, it has a sufficient size larger than the free layer track width Twf, and specifically, is preferably equal to or larger than the size of the free layer track width Twf + 2Gs.

  4 and 5A and 5B are diagrams schematically showing the effects of the first and second hard bias films 151 and 152 of the present embodiment. By adopting the hard bias film structure of this embodiment, the hard bias magnetic field with respect to the film thickness of the hard bias film increases (FIG. 4), and the residual magnetization and the coercive force with respect to the film thickness of the first hard bias film 151 are increased. be able to.

  Next, the manufacturing process of the read head shown in FIG. 2 will be described with reference to the flowchart of FIG. A multilayer film constituting the magnetoresistive sensor 112 is deposited by sputtering (S11). Thereafter, a resist layer covering the region corresponding to the magnetoresistive sensor 112 is formed by resist coating and patterning (S12), and a track width of the magnetoresistive sensor 112 is formed by ion beam etching (IBE) (S13). By this etching, the second hard bias base film 217 to the sensor base layer 211 are etched.

  Thereafter, a junction end oxidation process (S14) is performed as necessary, and then a junction insulating film 118 is deposited (S15). Further, the first hard bias base film 116 and the hard bias film 151 are attached (S16). The deposition can be performed by ion beam deposition (IBD). Next, the resist layer 52 is peeled off by lift-off (S17). A second hard bias film 152 is deposited by IBD (S18), and then a hard bias cap film 117 is deposited by IBD (S19).

  After the first hard bias film 151 is attached and / or after the second hard bias film 152 is not attached, the region on the magnetoresistive sensor 112 and its vicinity may be planarized by chemical mechanical polishing (CMP). Thereby, a required area | region can be planarized and the flatness can be raised.

  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 present invention can be applied to a magnetoresistive sensor having a free layer below the fixed layer. The first hard bias film or the second hard bias film can be formed of a plurality of layers. Although it is preferable to form both the first and second hard bias layer underlayers and control the orientation as described above, only one of the underlayers may be formed to control the orientation.

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 CPP read head concerning this embodiment. It is a figure which shows typically the flux of the hard bias film | membrane structure which concerns on this embodiment, and the conventional hard bias film | membrane structure. It is a figure which shows typically the effect by the hard bias film | membrane structure which concerns on this embodiment. It is a figure which shows typically the effect by the hard bias film | membrane structure which concerns on this embodiment. It is a flowchart which shows the flow of the manufacturing process of the CPP read head concerning this embodiment. It is sectional drawing which shows typically the structure of the read head in 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 CPP read head 61, 111 Lower shield, 112 Magnetoresistive sensor 113 Upper shield, 116 First hard bias base film 117 Hard bias cap film, 121 Thin film coil, 122 Recording magnetic pole 151 First hard bias film, 152 Second hard bias film, 211 Sensor base layer 212 Antiferromagnetic film, 213 Fixed layer, 214 Non Magnetic intermediate layer, 215 free layer 216 sensor cap film, 217 second hard bias base film,
611 Lower shield, 613 Upper shield, 612 Magnetoresistive sensor 261 Sensor underlayer, 262 Antiferromagnetic film, 263 Fixed layer, 264 Nonmagnetic intermediate layer 265 Free layer, 266 Sensor cap film, 615 Hard bias film 616 Under hard bias Geological film

Claims (7)

A magnetoresistive sensor film having a free layer, a fixed layer, and a nonmagnetic intermediate layer between the free layer and the fixed layer;
An upper shield and a lower shield formed so as to sandwich the magnetoresistive sensor film in the vertical direction;
A first hard bias film formed on both sides of the magnetoresistive sensor film and made of a hard magnetic material for controlling the magnetic domain of the free layer;
A second hard made of a hard magnetic material is formed between the upper shield and the free layer and between the first hard bias film and the upper shield and is in contact with the first hard bias film. A bias film;
CPP magnetic read head with The upper surface of the second hard bias film is flat in the vicinity of junctions on both sides of the magnetoresistive sensor film,
The CPP magnetic read head of claim 1. The second hard bias film and the free layer are magnetically isolated;
The CPP magnetic read head of claim 1. A base film for controlling the orientation of the second hard bias film is further formed between the free layer and the second hard bias film in contact with the lower surface of the second hard bias film. ,
The CPP magnetic read head of claim 1. The base film is a Cr or Cr alloy film that is a (200) orientation film,
The second hard bias film is a Co alloy (100) C-axis in-plane alignment film,
The CPP magnetic read head of claim 4. A base film for controlling the orientation of the first hard bias film is further formed in contact with the lower surface of the first hard bias film;
The base film of the first hard bias film is a Cr or Cr alloy film that is a (200) orientation film,
The first hard bias film is a Co alloy (100) C-axis in-plane alignment film,
The CPP magnetic read head of claim 5. The first hard bias film has a saturation magnetic flux density and a residual magnetic flux density larger than those of the second hard bias film,
The second hard bias film has a larger coercive force than the first hard bias film;
The CPP magnetic read head of claim 1.

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