Patent Publication Number: US-2007109684-A1

Title: Thin film magnetic head for perpendicular recording

Description:
This application claims the benefit of Japanese Patent Application No. 2005-332869 filed Nov. 17, 2005, which is hereby incorporated by reference.  
     BACKGROUND  
      1. Field  
      The present embodiments relate to a thin film magnetic head for perpendicular recording.  
      2. Related Art  
      There is known a thin film magnetic head that magnetizes a hard film of a recording medium in a perpendicular direction by applying a perpendicular magnetic field to the recording medium, which is called a perpendicular recording magnetic head (see JP-A-2001-43511 and JP-A-2005-122831 (US2005083608A1)).  FIG. 5  shows a schematic cross-sectional view of a known perpendicular recording magnetic head.  
      In a thin film magnetic head  110 , a slider  111  is formed of a non-magnetic material, such as Al 2 O 3  TiC. A surface  111   a  of the slider  111  faces the recording medium M. When the recording medium M rotates, the slider  111  floats from a surface of the recording medium M by airflow along the surface and the slider  111  is kept at a predetermined gap from the recording medium M.  
      In  FIG. 5 , a traveling direction of the recording medium M with respect to the slider  111  is an A direction. As shown in  FIG. 5 , a direction perpendicular to the paper represents an X axis, a direction perpendicular to the A direction and parallel to the paper represents a Y axis, and a direction parallel to the A direction but opposite thereto represents a Z axis. In addition, the Y axis direction is a height direction.  
      On a trailing end surface of the slider  111 , for example, an end surface in a direction opposite to the A direction in the drawing, a first coil layer  118  having a plurality of conductive members formed of a conductive non-magnetic material is formed through a coil insulating base layer  117 . A coil insulating layer  119  formed of an inorganic insulating material, such as Al 2 O 3 , is formed around the first coil layer  118 .  
      An upper surface  119   a  of the coil insulating layer  119  is planarized, and a main magnetic pole  120 , a width of which in a track width direction at an opposing surface  110   a  is set to a track width, is formed on the upper surface  119   a . The main magnetic pole  120  is formed through plating of a ferromagnetic material that has a high saturated magnetic flux density, such as Ni—Fe, Co—Fe, or Ni—Fe—Co, for example.  
      An insulating material layer  122  is provided around the main magnetic pole  120 . An upper surface  120   c  of the main magnetic pole  120  and an upper surface  122   a  of the insulating material layer  122  formed around the main magnetic pole  120  are flush with each other.  
      A gap layer  123  formed of a non-magnetic material, such as alumina or SiO 2 , is provided on the main magnetic pole  120  and a yoke portion  121 , and the insulating material layer  122 .  
      A second coil layer  125  is formed on the gap layer  123  with a coil insulating base layer  124  interposed therebetween. Like the first coil layer  118 , the second coil layer  125  may have a plurality of conductive members  125  formed of a conductive non-magnetic metal material.  
      The first coil layer  118  and the second coil layer  125  are electrically connected to each other such that end portions in the track width direction (X direction in the drawing) form a troidal coil. With the first coil layer  118  and the second coil layer  125 , a troidal coil layer that is wound with the main magnetic pole  120  and yoke portion  121  as a core is formed.  
      A coil insulating layer  126  made of an organic insulating material, such as a resist is formed on the second coil layer  125  covering around the second coil layer  125 . A return yoke layer  127  is formed continuously to cover the coil insulating layer  126 . The gap layer  123  is made of a ferromagnetic material, such as Permalloy. A front end surface  127   a  of the return yoke layer  127  is exposed at the opposing surface  110   a . In addition, on a side higher than the opposing surface  110   a , the main magnetic pole  120  is connected to the return yoke layer  127  through a connection portion  127   b  of the return yoke layer  127 . Accordingly, a magnetic path connecting the main magnetic pole  120  and the return yoke layer  127  is formed.  
       FIG. 6  is a plan view that shows the thin film magnetic head before the return yoke layer  127  is formed. A slot height determining layer  128  is formed of an inorganic or an organic material on the gap layer  123  at a position space at a predetermined distance from the opposing surface  110   a  to the recording medium. A slot height (gap depth) length of the magnetic head is defined by the distance from the opposing surface  110   a  to a front edge of the slot height determining layer  128 . The slot height determining layer  128  is formed longer than the second coil layer  125  and the coil insulating layer  126  in the track width direction.  
      In the related art, the slot height determining layer  128  is formed along the opposing surface  110   a  and the second coil layer  125  is formed on the slot height determining layer  128 . Then, the coil insulating layer (resist)  126  formed by an organic insulating layer formed to cover the slot height determining layer  128  and the second coil layer  125 .  
      However, since the coil insulating layer  126  has a rectangular shape in plan view and is rectangular parallelepiped in appearance, when the coil insulating layer  126  is baked, the organic insulating layer is shrunk and a corner portion of the rectangular shape rises, such that angular protrusions  126   a  may be formed (see  FIG. 7 ). For example, if the angular protrusions  126   a  are formed at both corners of the coil insulating layer  126  close to the opposing surface  110   a , the angular protrusions  126   a  are transferred to the return yoke layer  127  formed on the coil insulating layer  126  and then protrusions  127   c  are formed at the upper surface of the return yoke layer  127  (see  FIG. 8 ). If the protrusions  127   c  are formed at corners of the return yoke layer  127  around the opposing surface  110   a , there is a problem in that a magnetic flux to be returned to the return yoke layer  127  from the main magnetic pole  120  is disturbed or becomes abnormal.  
     SUMMARY  
      The present embodiments may obviate one or more limitations of the related art. For example, in one embodiment, a thin film magnetic head prevents occurrence of an abnormal shape, such as a protrusion of a coil insulating layer.  
      In one embodiment, a thin film magnetic head includes a first magnetic portion that has a main magnetic pole at an opposing surface to a recording medium. A second magnetic portion is formed to be apart from the first magnetic portion in a perpendicular direction. A coil layer is formed between the first magnetic portion and the second magnetic portion.  
      A slot height determining layer is formed on a gap layer of the first magnetic portion at a position spaced at a predetermined distance from the opposing surface in a height direction so as to extend in a track width direction. The coil layer is formed at an upper surface of the gap layer in a height direction from the slot height determining layer.  
      In one embodiment, a coil insulating layer is formed to cover the slot height determining layer and the coil layer while exposing one end of the first magnetic portion in the height direction. The second magnetic portion is formed to cover the coil insulating layer and the exposed first magnetic portion. In the coil insulating layer, an inclination portion is formed to be inclined in the height direction in which a distance from the opposing surface becomes longer in the vicinities of both sides of the first magnetic portion along the opposing surface.  
      In one embodiment, a length of the slot height determining layer along the opposing surface may be longer than a length of the track width direction of the main magnetic pole and shorter than a length of the track width direction of the second magnetic portion. A portion of the coil insulating layer on the slot height determining layer may have an opposing portion that extends along the slot height determining layer and inclination portion that are inclined from both end portions of the slot height determining layer.  
      In one embodiment, an inclination portion and a side portion of the coil insulating layer along an edge that extends in the height direction of the first magnetic portion may have an obtuse angle.  
      In one embodiment, an inclination portion and a side portion of the coil insulating layer along an edge extending in the height direction of the first magnetic portion may form a curved portion. In the coil insulating layer, the inclination portion may have an outwardly convex shape.  
      In one embodiment, the first magnetic portion that has a main magnetic pole at a track width at an opposing surface to a recording medium, and the second magnetic portion that is formed to be wider than the track width are formed to be spaced from each other in a perpendicular direction. A second coil layer is interposed between the first magnetic portion of the first coil layer and the second magnetic portion. The first magnetic portion and the second magnetic portion are electrically connected to each other. A solenoid coil layer is formed to be wound around the first magnetic portion in a solenoid shape. The coil layer serves as the second coil layer.  
      In one embodiment, since the opposing surface of the coil insulating layer is the inclination portion inclined in the height direction, the side portion extending in the height direction is connected to the inclination portion at the obtuse angle and the angular protrusions do not occur at the corners of the coil insulating layer even though the coil insulating layer is subject to baking. Accordingly, the protrusions do not occur in the second magnetic portion to which the surface shape of the coil insulating layer is transferred and disorder of the magnetic flux does not occur.  
      In one embodiment, the slot height determining layer is longer than the length of the track width of the main magnetic pole and shorter than a length of the track width of the second magnetic portion, such that the inclination portions are formed from both end portions of the slot height determining layer. Therefore, efficiency of the magnetic flux to be returned to the second magnetic portion from the main magnetic pole is increased.  
      According to one embodiment with a portion connecting the inclination portion and the side part as a curved portion, it is possible to prevent the angular protrusions from occurring. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a longitudinal cross-sectional view that illustrates a thin film magnetic head of an embodiment;  
       FIG. 2  is a plan view that illustrates the thin film magnetic head in which a coil insulating layer is formed but a return yoke layer is not formed;  
       FIG. 3  is a view that illustrates the thin film magnetic head by an electron microscope before the return yoke layer is formed;  
       FIG. 4  is a plan view that illustrates the thin film magnetic head in which the return yoke layer is formed;  
       FIG. 5  is a longitudinal cross-sectional view that illustrates a thin film magnetic head according to the related art;  
       FIG. 6  is a plan view that illustrates the thin film magnetic head in which a coil insulating layer is formed but a return yoke layer is not formed according to the related art;  
       FIG. 7  is a view that illustrates the thin film magnetic head by an electron microscope in a state where a coil insulating layer is formed but a return yoke layer is not formed according to the related art; and  
       FIG. 8  is a plan view that illustrates the thin film magnetic head in which the return yoke layer is formed according to the related art. 
    
    
     DETAILED DESCRIPTION  
       FIG. 1  is a longitudinal cross-sectional view that illustrates a magnetic head of one embodiment. The magnetic head  10  is a perpendicular recording magnetic head that magnetizes a hard film of a recording medium M in a perpendicular direction by applying a perpendicular magnetic field to the recording medium M using a writing head portion HW provided at an opposing surface  10   a.    
      The perpendicular magnetic head  10  has a slider  11  that is formed of a non-magnetic material, for example Al 2 O 3  TiC, and a surface  11   a  of the slider  11  opposes the recording medium M. When the recording medium M rotates, the slider  11  floats from the surface of the recording medium M and the slider  11  is kept apart at a predetermined gap from the recording medium M.  
      In  FIG. 1 , a traveling direction of the recording medium M with respect to the slider  11  is an A direction. As shown in  FIG. 1 , a direction perpendicular to the paper represents an X axis, a direction perpendicular to the A direction and parallel to the paper represents a Y axis, and a direction parallel to the A direction but opposite thereto represents a Z axis. The Y direction is a height direction.  
      As shown in  FIG. 1 , in the perpendicular magnetic head  10 , individual members are formed in the Z axis direction (in a direction opposite to an arrow A) on a trailing end surface  11   b  of the slider  11 . A non-magnetic insulating layer  12  formed of an inorganic material, for example, Al 2 O 3  or SiO 2 , is formed on the trailing end surface  11   b  of the slider  11 . A reading head portion HR is formed on the non-magnetic insulating layer  12 . The reading head portion HR includes a lower shield layer  13 , an upper shield layer  16 , and a reading element  14  disposed in an inorganic insulating layer (gap insulating layer)  15  interposed between the lower shield layer  13  and the upper shield layer  16 . In addition, the reading element  14  is a magnetoresistive effect element, for example, AMR, GMR, or TMR. A writing head portion HW for perpendicular recording is formed on the upper shield layer  16  of the reading head portion HR.  
      On the upper shield layer  16 , a first coil layer  18  that has a plurality of conductive members  18   a  formed of a conductive material is formed through a coil insulating base layer  17 . The first coil layer  18  may have a single layer structure or a laminated structure of one conductive non-magnetic metal material or two or more conductive non-magnetic metal materials selected from a group of, for example, Au, Ag, Pt, Cu, Cr, Al, Ti, NiP, Mo, Pd, or Rh.  
      A coil insulating layer  19  formed of an inorganic insulating material, for example, Al 2 O 3 , or an organic insulating material, such as resist, is formed around the first coil layer  18 . An upper surface  19   a  of the coil insulating layer  19  is planarized, and a main magnetic pole  20  is formed at the upper surface  19   a , such that a width in a track width direction of an end surface  20   a  exposed at the opposing surface  10   a  becomes a track width. The main magnetic pole  20  is formed in a tapered shape in the height direction (at the rear side) from the opposing surface  10   a . The main magnetic pole  20  is formed by plating of a ferromagnetic material that has a high saturated magnetic flux density, for example, Ni—Fe, Co—Fe, or Ni—Fe—Co. In one embodiment, on the main magnetic pole  20 , a rectangular portion extending in the height direction from a wider portion of the tapered portion forms a yoke portion  21 . The main magnetic pole  20  and the yoke portion  21  form a first magnetic portion.  
      On the upper surface  19   a  of the coil insulating layer  19 , an insulating material layer  22  is provided around the main magnetic pole  20 . An upper surface of the insulating material layer  22  formed around the main magnetic pole  20  are flush with an upper surface of the main magnetic pole  20 . The insulating material layer  22  can be formed of one material or two or more materials selected from a group of, for example, alumina (Al 2 O 3 ), SiO2, Al—Si—O, Ti, W, or Cr.  
      A gap layer  23  formed a non-magnetic material, for example, alumina, SiO 2 , Au, or Ru, is provided on the main magnetic pole  20  and the yoke portion  21 , and on the insulating material layer  22 .  
      A second coil layer  25  is formed on the gap layer  23  with a coil insulating base layer  24  interposed therebetween. Like the first coil layer  18 , the second coil layer  25  has a plurality of conductive members  25   a  formed of, for example, a conductive non-magnetic metal material. The second coil layer  25  is formed of one material or two or more materials selected from a group of, for example, Au, Ag, Pt, Cu, Cr, Al, Ti, NiP, Mo, Pd, or Rh. In one embodiment, the second coil layer  25  may have a laminated structure of the non-magnetic metal materials. The insulating layer includes the insulating material layer  22 , the gap layer  23 , and the coil insulating base layer  24 .  
      Though not shown, the conductive portion  18   a  of the first coil layer  18  and the conductive portion  25   a  of the second coil layer  25  are electrically connected to each other such that respective end portions in the track width direction (X direction in the drawing) form a solenoid coil. The first coil layer  18  and the second coil layer  25  form a solenoid coil layer that is wound with the main magnetic pole  20  and the yoke portion  21  as a core. In this embodiment, the width of the first coil layer  18  in the height direction (Y direction in the drawing) is the same as the width of the second coil layer  25  in the height direction (Y direction in the drawing).  
      A coil insulating layer  26  formed of an organic insulating material, such as resist, is formed around the second coil layer  25 . A return yoke layer  27  that forms a second magnetic portion is continuously formed to cover the coil insulating layer  26  and the gap layer  23  using a ferromagnetic material, such as Permalloy. The front end  27   a  of the return yoke layer  27  is exposed at the opposing surface  10   a  to the recording medium. In one embodiment, on a side higher than the opposing surface  10   a , the main magnetic pole  20  is connected to the return yoke layer  27  through a connection portion  27   b  of the return yoke layer  27  exposed from the coli insulating layer  26 . Accordingly, a magnetic path that connects the main magnetic pole  20  and the return path layer  27  is formed. In another embodiment, a thin film magnetic head may have the main magnetic pole  20  which is not connected to the return yoke layer  27 , for example, having no connection portion  27   b.    
      A slot height determining layer  28  is formed on the gap layer  23  by using an inorganic or an organic material at a position spaced at a predetermined distance from the opposing surface  10   a . A slot height (gap depth) length of the perpendicular magnetic head  10  is defined by a distance from the opposing surface  10   a  to a front end of the slot height determining layer  28 .  
      In the height direction (Y direction in the drawing) of the connection portion  27   b  of the return yoke layer  27 , a lead layer  29  extending from the second coil layer  25  is formed on the coil insulating base layer  24 . The return yoke layer  27  and the lead layer  29  are covered with a protective layer  30  formed of an inorganic non-magnetic insulating material or the like.  
       FIG. 2  is a plan view that illustrates a thin film magnetic head in which a coil insulating layer  26  is formed but a return yoke layer  27  is not formed.  FIG. 3  is a view by an electron microscope after the thin film magnetic head is subject to baking.  FIG. 4  is a plan view that schematically illustrates the thin film magnetic head in which the return yoke layer  27  is formed.  
      The slot height determining layer  28  is formed along the opposing surface  10   a  so as to have substantially the same width as the yoke portion  21  of the main magnetic pole  20 . For example, the height determining layer  28  is longer than the length of the track width direction of the main magnetic pole  20  and is shorter than the length of the track width direction of the return yoke layer  27  that forms a second magnetic portion. With this configuration, in the appearance of the coil insulating layer  26 , a portion over the slot determining layer  28  becomes an opposing portion  26   a  that overlaps the slot determining layer  28  and, at both end portions of the opposing portion  26   a  around the slot determining layer  28 , inclination portions  26   b  are formed to be inclined in the height direction away from the opposing surface  10   a . In addition, in the coil insulating layer  26 , a curved portion  26   c  extends from the inclination portion  26   b  and a side portion  26   d  is continuously connected to the curved portion  26   c  and extend in the height direction substantially perpendicular to the opposing surface  10   a.    
      Baking is performed for the perpendicular magnetic head  10  on which the coil insulating layer  26  is formed so as to dry a solvent of the organic insulating layer (see  FIG. 3 ). In the coil insulating layer  26 , the inclination portion  26   b  and the side portion  26   d  have an obtuse angle to be connected through the curved portion  26   c . Accordingly, when the coil insulating layer  26  is subject to baking, even though the coil insulating layer  26  is shrunk, the curved portion  26   c  is bent backward such that neither angular protrusion is formed nor the coil insulating layer  26  is transformed. For example, a surface and the appearance of the coil insulating layer  26  are smoothly formed. In one embodiment, boundary portions of the facing portion  26   a , the inclination portion  26   b , the curved portion  26   c , and the side portion  26   d  are wound.  
      Subsequently, the return yoke layer  27  is formed around the coil insulating layer  26  on the gap layer  23 , the slot height determining layer  28 , the coil insulating layer  26 , the mail magnetic pole  20 , and the yoke portion  21 . In one embodiment, surface shapes of the gap layer  23 , the slot height determining layer  28 , and the coil insulating layer  26  of the base layer are transferred to the return yoke layer  27 . Since the surface shape of the coil insulating layer  26  is smooth (see  FIG. 3 ), the shape of the return yoke layer  27  to which the surface shape of the coil insulating layer  26  is transferred becomes smooth. Therefore, there is no thorn or protrusion.  
      In one embodiment, a corner portion of the return yoke layer  27  to which the shape of the curved portion  26   c  of the coil insulating layer  26  is transferred is a curved surface portion  27   c  and there is no protrusion. Therefore, the curved surface portion  27   c  of the return yoke layer  27  rarely affects the magnetic flux to be returned to the return yoke layer  27  from the main magnetic pole  20 . The slot height determining layer  28  is formed to be narrower than the width of the yoke portion  21  of the main magnetic pole  20 . Therefore, the magnetic flux to be returned to the return yoke layer  27  from the main magnetic pole  20  converges on the return yoke layer  27  around the opposing portion  27   a , thereby improving efficiency.  
      In another embodiment, the yoke portion  21  of the main magnetic pole  20  is exposed from the end portion of the coil insulating layer  26  in the height direction. Therefore, the side surface in the height direction where the coil insulating layer  26  comes into contact with the yoke portion  21  is smooth. Accordingly, upon plating of the return yoke layer  27 , it is not necessary to etch the yoke portion  21 .  
      In one embodiment, an angle between the inclination portion  26   b  and the Y axis direction is not less than about 5 degrees and less than about 30 degrees. For example, even though the angle between the side portion  26   d  and the inclination portion  26   b  is an obtuse angle less than 90 degrees, a preferable angle is approximately 110 degrees. In addition, the same effect can be obtained when the inclination portion  26   b , the curved portion  26   c , and the side portion  26   d  are formed in an outwardly convex shape, for example, when the inclination portion  26   b , the curved portion  26   c , and the side portion  26   d  are formed in an outwardly curved line in a convex shape in plan view. In one embodiment, the curved surface portion  26   c  has a three-dimensionally smooth convex shape.  
      In one embodiment, a spiral perpendicular magnetic head can be used instead of a solenoid coil type perpendicular magnetic head.  
      Various embodiments described herein can be used alone or in combination with one another. The forgoing detailed description has described only a few of the many possible implementations of the present invention. For this reason, this detailed description is intended by way of illustration, and not by way of limitation. It is only the following claims, including all equivalents that are intended to define the scope of this invention.