Abstract:
The magnetic head of the present invention has a narrow upper magnetic pole and capable of restricting side erasure and record bleeding. The magnetic head for writing data on a recording medium comprises: an upper magnetic pole including a pole section, which faces the recording medium and has a prescribed width; and a lower magnetic pole including grooves, which are respectively formed on the both sides of the pole section, wherein level of edges of the grooves are lower than that of an upper face of the lower magnetic pole.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a magnetic head and a method of manufacturing the magnetic head.  
           [0002]    Recording density of magnetic disk drives and magnetic tape recorder have been made higher, so magnetic heads, which have narrow core width and capable of restricting record bleeding, are required.  
           [0003]    Japanese Patent Gazette No. 11-7608 discloses a method of manufacturing a magnetic head having narrow core width, in which an upper magnetic pole is trimmed by a focussed ion beam (FIB). In the FIB trimming step, parts of a lower magnetic pole respectively located on the both sides of the upper magnetic pole are trimmed or grooved unit reaching prescribed depth, and width of the upper and lower magnetic poles are made equal so as to make recording density higher. Further, a distance between the upper magnetic pole and an upper face of the lower magnetic pole is made longer so as to prevent side erasure of magnetic flux and record bleeding as much as possible.  
           [0004]    However, the above described conventional technology has following disadvantages.  
           [0005]    [0005]FIG. 15 is a schematic view of the upper magnetic pole  10  and the lower magnetic pole  12  before the FIB trimming is executed. A gap layer  14  is made of alumina, SiO 2 , etc.. FIG. 16 is a schematic view of the both after the FIB trimming is executed.  
           [0006]    FIB is capable of trimming and forming the upper magnetic pole  10  into a narrow pole with high accuracy, but V-shaped grooves  16 , which are inclined outward, are simultaneously formed at parts of the lower magnetic pole  12  located on the both sides of the upper magnetic pole  10 . Therefore, edges  18  must be formed in the lower magnetic pole  12 . Magnetic flux is apt to concentrate to the edges  18 , so side erasure and record beeding are apt to be occurred.  
           [0007]    Further, if width of the grooves is made wider, by FIB, so as to make the distance between the edges  18  and the upper magnetic pole  10  longer, throughput must be sharply made lower.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention has been invented so as to solve the above described disadvantages of the conventional technology.  
           [0009]    An object of the present invention is to provide a magnetic head which has a narrow upper magnetic pole and capable of restricting side erasure and record bleeding.  
           [0010]    Another object of the present invention is to provide a method of manufacturing the magnetic head.  
           [0011]    To achieve the objects, the magnetic head for writing data on a recording medium comprises: an upper magnetic pole including a pole section, which faces the recording medium and has a prescribed width; and a lower magnetic pole including grooves, which are respectively formed on the both sides of the pole section, wherein level of edges of the grooves are lower than that of an upper face of the lower magnetic pole.  
           [0012]    The method of manufacturing a magnetic head for writing data on a recording medium comprises the steps of: forming an upper magnetic pole on a lower magnetic pole with a gap layer; trimming parts of the lower magnetic pole respectively located on the both sides of the upper magnetic pole, by an ion mill, until reaching prescribed depth; and trimming both side faces of the upper magnetic pole and further trimming the parts of the lower magnetic pole on the both sides of the upper magnetic pole by a focussed ion beam.  
           [0013]    Another method comprises the steps of: forming an upper magnetic pole on a lower magnetic pole with a gap layer; trimming both side faces of the upper magnetic pole and parts of the lower magnetic pole respectively located on the both sides of the upper magnetic pole by a focussed ion beam; further trimming the parts of the lower magnetic pole on the both sides of the upper magnetic pole, by an ion mill, until reaching prescribed depth.  
           [0014]    In the present invention, core width of the upper magnetic pole can be narrower, and side erasure can be restricted. Further, the level of the edges of the grooves are lower than that of the upper face of the lower magnetic pole, so that the distance between the edges and the side faces of the upper magnetic pole can be longer, so that concentration of magnetic flux to the edges and record bleeding can be restricted. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    Embodiments of the present invention will now be described by way of examples and with reference to the accompanying drawings, in which:  
         [0016]    FIGS.  1 - 3  show the steps of manufacturing a magnetic head and are seen from a front end of the magnetic head, wherein  
         [0017]    [0017]FIG. 1 is a sectional view in which a gap layer has been formed;  
         [0018]    [0018]FIG. 2 is a sectional view in which a window for forming an upper magnetic pole has been formed on photo resist; and  
         [0019]    [0019]FIG. 3 is a sectional view in which the upper magnetic pole has been formed;  
         [0020]    FIGS.  4 - 6  show the steps of manufacturing the magnetic head and are seen from a side of a coil section of the magnetic head, wherein  
         [0021]    [0021]FIG. 4 is a sectional view in which a coil has been formed;  
         [0022]    [0022]FIG. 5 is a sectional view in which the photo resist has been applied; and  
         [0023]    [0023]FIG. 6 is a sectional view in which the upper magnetic pole has been formed;  
         [0024]    [0024]FIG. 7 is a plan view showing the upper magnetic pole and the coil;  
         [0025]    FIGS.  8 - 10  show the steps of a first method for trimming the upper magnetic pole, wherein  
         [0026]    [0026]FIG. 8 is an explanation view of a state before trimming;  
         [0027]    [0027]FIG. 9 is an explanation view of a state after ion mill trimming is executed; and  
         [0028]    [0028]FIG. 10 is an explanation view of a state after FIB trimming is executed;  
         [0029]    FIGS.  11 - 13  show the steps of a second method for trimming the upper magnetic pole, wherein  
         [0030]    [0030]FIG. 11 is an explanation view of a state before trimming;  
         [0031]    [0031]FIG. 12 is an explanation view of a state after FIB trimming is executed; and  
         [0032]    [0032]FIG. 13 is an explanation view of a state after ion mill trimming is executed;  
         [0033]    [0033]FIG. 14 is an exploded perspective view of a main part of the magnetic head;  
         [0034]    [0034]FIGS. 15 and 16 show the steps of the conventional method for trimming the upper magnetic pole, wherein  
         [0035]    [0035]FIG. 15 is a schematic view before trimming is executed; and  
         [0036]    [0036]FIG. 16 is a schematic view after FIB trimming is executed. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0037]    The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.  
         [0038]    In the present embodiments, an upper magnetic pole is formed by the conventional manner. An example will be briefly explained.  
         [0039]    Firstly, as shown in FIG. 1, a protection film  21  made of alumina, a lower magnetic shielding layer  22  made of an Fe—Ni alloy and a first nonmagnetic insulating layer  23  made of alumina are formed on a circular disk-shaped wafer  20  made of alumina-titanium-carbide (Al 2 O 3 TiC), ferrite or calcium titanate.  
         [0040]    Next, a plurality of magnetic transducers  24  are formed on the insulating layer  23 . The transducers  24  are arranged, on the insulating layer  23 , in a prescribed pattern. Anisotropy magneto-resistive elements, spin-valve magneto-resistive elements or the like are used as the magnetic transducers  24 . A pair of leads  24   a  are respectively connected to both ends of each of the magnetic transducers  24 , and the leads  24   a  are extended to the insulating layer  23 .  
         [0041]    A second nonmagnetic insulating layer  25  made of alumina, which covers the magnetic transducer  24  and the leads  24   a,  is formed on the insulating layer  23 . An upper shielding layer  26  made of an Fe—Ni alloy is formed on the insulating layer  25 .  
         [0042]    A recording gap layer  27  made of alumina, whose thickness is about 0.20-0.6 μm, is formed on the shielding layer  26 .  
         [0043]    Note that, in the case of a magnetic head having an induction coil, the upper shielding layer  26  acts as a lower magnetic pole layer, so it will be called the lower magnetic pole  26 .  
         [0044]    As shown in FIG. 4, a coil  30  sandwiched between a third nonmagnetic insulating layer  28  and a fourth nonmagnetic insulating layer  29  is formed on the gap layer  27 . A hole  31  passing a center of the coil  30  is formed in the insulating layers  28  and  29  and the gap layer  27 .  
         [0045]    Note that, FIG. 1 is a sectional view taken along a line A-A shown in FIG. 4.  
         [0046]    Next, as shown in FIGS. 2 and 5, a plating base layer  32  made of an alloy including Fe, Ni, Co, etc. is formed on the gap layer  27 , the insulating layer  29  and a surface of the hole  31 . Then, photo resist is applied on the plating base layer  32 , then the layer is exposed and developed so as to form a window  33   a  for forming the upper magnetic pole.  
         [0047]    The upper magnetic pole  34 , which is made of an alloy including Fe, Ni, Co, etc. and whose thickness is about 5 μm, is formed in the window  33   a  by electrolytic plating. Then, as shown in FIGS. 3 and 6, the photo resist  33  is removed.  
         [0048]    As shown in FIG. 7, the upper magnetic pole  34  is formed into a thin pole section  34   a  in a range in which the upper magnetic pole  34  faces a recording medium, and the opposite part of the upper magnetic pole  34  is connected to the lower magnetic pole  26  via the hole  31 .  
         [0049]    Note that, the material of the magnetic shielding layer  22 , the lower magnetic pole  26  and the upper magnetic pole  34  are not limited to the Fe—Ni alloy. And they may be formed by not only electrolytic plating but also spattering, etc..  
         [0050]    The upper magnetic pole  34  is formed by the above described manner.  
         [0051]    The feature of the present invention is methods of trimming the upper magnetic pole  34 .  
         [0052]    FIGS.  8 - 10  show the steps of a first method.  
         [0053]    [0053]FIG. 8 shows the upper magnetic pole  34  and the lower magnetic pole  26  before the trimming is executed.  
         [0054]    Firstly, as shown in FIG. 9, an ion beam irradiates to the pole section  34   a  of the upper magnetic pole  34  and its periphery while the substrate  20  is rotated. By this ion mill trimming, the plating base layer  32  in a prescribed range, in which the ion beam has been applied, is removed, then the gap layer  27  is removed by reactive ion etching (RIF). Further, the lower magnetic pole  26  is partially trimmed or grooved until reaching prescribed depth, so that a concave section  26   a  is formed in the lower magnetic pole.  
         [0055]    The ion beam diagonally irradiates to the substrate  20 .  
         [0056]    Parts of a surface of the lower magnetic pole  26 , which are located in the vicinity of the pole section  34   a,  are apt to be shaded from the ion beam by the pole section  34   a,  so amount of the ion beam applied to the parts is less than that applied to other parts. Parts of a surface of the concave section  26   a,  which are located near the pole section  34   a,  is higher than other parts thereof. Namely, the surface of the concave section  26   a  is formed into a tapered shape. Amount of trimming the lower magnetic pole  26  or depth of the concave section  26   a  is about 1 μm.  
         [0057]    Next, both side faces of the pole section  34   a  and upper parts of the lower magnetic pole  26  on the both sides of the pole section  34   a  are trimmed by an FIB having width of “m”.  
         [0058]    By the FIB trimming, the pole section  34   a  and the upper parts of the lower magnetic pole  26  are trimmed and made thin until reaching prescribed width, and V-shaped grooves  26   b  inclined outward are formed, on the both sides of the pole section  34   a,  in the lower magnetic pole  26 . With this structure, edges  26   c  are formed in the concave section  26   a.    
         [0059]    FIB is applied to the surface of the concave section  26   a,  which has been made lower by the ion mill trimming and whose level is lower than other parts of the lower magnetic pole  26 , so that the surface of the concave section  26   a  is further trimmed. Therefore, level of the edges  26   c  are lower than that of the edges  18  (see FIG. 16), which are formed by the conventional method. Unlike the conventional method, the distance between the side faces of the pole section  34   a  of the upper magnetic pole  34  and the edges  26   c  can be made longer, so that side erasure of magnetic flux can be restricted and record bleeding can be reduced.  
         [0060]    Another method of trimming the upper magnetic pole  34  will be explained with reference to FIGS.  11 - 13 .  
         [0061]    [0061]FIG. 11 shows a state before the trimming is executed.  
         [0062]    In the present embodiment, the both side faces of the pole section  34   a  of the upper magnetic pole  34  and upper parts of the lower magnetic pole  26  on the both sides of the pole section  34   a  are trimmed by an FIB having width of “m”.  
         [0063]    By the FIB trimming, the pole section  34   a  and the upper parts of the lower magnetic pole  26  are trimmed and made thin until reaching prescribed width, and the V-shaped grooves  26   b  inclined outward are formed, on the both sides of the pole section  34   a,  in the lower magnetic pole  26 . At that time, the plating base layer  32  in a prescribed range, in which the FIB has been applied, and the gap layer  27  are removed.  
         [0064]    By the FIB trimming, edges  26   c  of the V-shaped grooves  26   b  are formed. These steps are executed by the conventional method.  
         [0065]    In the present embodiment, as shown in FIG. 13, the ion mill trimming is further executed.  
         [0066]    The surface of the lower magnetic pole  26  including the V-shaped grooves  26   b  is further trimmed until reaching a prescribed depth. Therefore, the level of the edges  26   c  are further made lower than that shown in FIG. 12. Namely, the distance between the side faces of the pole section  34   a  of the upper magnetic pole  34  and the edges  26   c  can be made longer, so that side erasure of magnetic flux can be restricted and record bleeding can be reduced.  
         [0067]    In the both methods of the above described embodiments, the pole section  34   a  of the upper magnetic pole  34  is made thin, and the V-shaped grooves  26   b  inclined outward are formed, on the both sides of the pole section  34   a,  in the lower magnetic pole  26 . The side faces of the pole section  34   a  and inner faces of the V-shaped grooves  26   b  are smoothly connected. The width of the pole section  34   a  is equal to that of an upper part of the lower magnetic pole  26 . The level of the edges  26   c  of the grooves  26   b  are lower than that of an upper face  26   d  of the lower magnetic pole  26 .  
         [0068]    To completely produce the magnetic head, electrode pads (not shown), which will be connected to the transducer  24  and the coil  30 , are formed, and an alumina protection layer (not shown) is formed on the upper magnetic pole  34  so as to cover the upper magnetic pole  34 .  
         [0069]    The wafer (substrate)  20  is not separated until completing the step of forming the protection layer. Namely, a plurality of the magnetic heads are matrically arranged in the wafer  20 .  
         [0070]    The wafer  20  is cut to form a plurality of bar-shaped members, in each of which the magnetic heads are linearly arranged, an air bearing surface of the bar-shaped member is abraded, rails for floating sliders are formed, then the bar-shaped member is cut to separate the magnetic heads respectively.  
         [0071]    Note that, FIG. 14 is an exploded perspective view of a main part of the magnetic head, which shows arrangement of the transducer  24 , etc.. A symbol  30  stands for a magnetic disk.  
         [0072]    The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.