Abstract:
The present invention discloses a method of manufacturing a magnetic head in which a magnetic yoke is formed on a substrate in parallel thereto by the thin film process, which comprises the steps of forming a yoke-patterned recess in a non-magnetic material layer formed on the substrate; and forming a magnetic yoke layer in such recess while forming a non-magnetic gap portion approximately normal to the substrate; wherein a split portion is provided to the gap portion so as to recess behind a level where a slide-contact plane with recording media is formed, which results in a magnetic head which can successfully prevent the noise generation over a long period, and can improve the playback efficiency.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a method of manufacturing a yoke-type magnetic head of the slide-contact type or the flotation type, and in particular to a method of manufacturing a yoke-type, thin-film magnetic head of the magneto-resistive effect type or the inductive type which is mounted on a rotating drum of a magnetic head device based on a helical scan system using a magnetic tape as a recording medium.  
           [0003]    2. Description of the Related Art  
           [0004]    A magnetic head employed in a magnetic tape device using a magnetic tape as a recording medium, which is typified by an inductive-type magnetic head having a ferrite core, suffers from a problem that output of a reproducing signal tends to be lower in high-density recording, particularly for a case where a reproducing track width is reduced as narrow as 5 μm or below. One measure for addressing such problem relates to a magnetic head having as a reproducing head a magneto-resistive effect element (MR element) or a spin valve element. Such magnetic head is provided so as to align the MR element at a plane which is brought into slide-contact with the magnetic tape, and so as to direct the magnetic gap in parallel to the substrate.  
           [0005]    Such a conventional magnetic head, however, causes time-dependent abrasion due to friction of the magnetic head with magnetic tapes, and accordingly generates noise due to changes in device morphology and thermal asperity, since the magneto-resistive effect device is provided at the slide-contact plane with magnetic tapes. Another problem resides in that the reproducing efficiency is intrinsically low since the magnetic gap is aligned in parallel to the substrate.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention is accomplished considering the foregoing situation, and it is therefore an object of the present invention is to provide a method of manufacturing a magnetic head capable of avoiding the noise generation over a long period and improving the reproducing efficiency.  
           [0007]    Such object of the present invention will be accomplished by a method of manufacturing a magnetic head in which a magnetic yoke is formed on a substrate in parallel thereto by a thin film process, comprising the steps of forming a yoke-patterned recess in a non-magnetic material layer formed on the substrate; and forming a magnetic yoke layer in the yoke-patterned recess while forming a non-magnetic gap portion approximately perpendicular to the substrate; wherein a split portion is provided to the gap portion so as to recess behind a level where a slide-contact plane with recording media is formed.  
           [0008]    In such constitution, a magneto-resistive effect device is provided as being recessed deep into the yoke-type magnetic head structure to thereby make it less susceptible to the morphological changes in the device structure or thermal asperity, which successfully prevents the noise generation over a long period. Moreover, possibility in the downsizing of a magnetic circuit will improve the reproducing efficiency. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The above and other objects, features and advantages of the present invention will become more apparent from the following description of the presently preferred exemplary embodiments of the invention taken in conjunction with the accompanying drawings, in which:  
         [0010]    [0010]FIG. 1 is a perspective view showing an embodiment of a magnetic head fabricated in accordance with the present invention;  
         [0011]    [0011]FIG. 2 is a schematic perspective view showing a process step for manufacturing the magnetic head shown in FIG. 1;  
         [0012]    [0012]FIG. 3 is a schematic perspective view showing a process step as continued from FIG. 2;  
         [0013]    [0013]FIGS. 4A and 4B are a schematic perspective view and a sectional view, respectively, showing a process step as continued from FIG. 3;  
         [0014]    [0014]FIG. 5 is a schematic perspective view showing a process step as continued from FIGS. 4A and 4B;  
         [0015]    [0015]FIG. 6 is a schematic perspective view showing a process step as continued from FIG. 5;  
         [0016]    [0016]FIG. 7 is a schematic perspective view showing a process step as continued from FIG. 6;  
         [0017]    [0017]FIG. 8 is a schematic perspective view showing a process step as continued from FIG. 7;  
         [0018]    [0018]FIGS. 9A and 9B are a schematic perspective view and a sectional view, respectively, showing a process step as continued from FIG. 8;  
         [0019]    [0019]FIGS. 10A and 10B are a schematic perspective view and a sectional view, respectively, showing a process step as continued from FIG. 9;  
         [0020]    [0020]FIG. 11 is a schematic perspective view showing a process step as continued from FIGS. 10A and 10B;  
         [0021]    [0021]FIG. 12 is a schematic perspective view showing a process step as continued from FIG. 11;  
         [0022]    [0022]FIG. 13 is a schematic perspective view showing a process step as continued from FIG. 12;  
         [0023]    [0023]FIG. 14 is a schematic perspective view showing a process step as continued from FIG. 13;  
         [0024]    [0024]FIG. 15 is a schematic perspective view showing a process step as continued from FIG. 14;  
         [0025]    [0025]FIG. 16 is a schematic perspective view showing a process step as continued from FIG. 15;  
         [0026]    [0026]FIG. 17 is a schematic perspective view showing a process step as continued from FIG. 16;  
         [0027]    [0027]FIG. 18 is a schematic perspective view showing a process step as continued from FIG. 17;  
         [0028]    [0028]FIG. 19 is a schematic perspective view showing a process step as continued from FIG. 18;  
         [0029]    [0029]FIGS. 20A to  20 E are schematic views showing a first method of manufacturing the yoke core of the magnetic head shown in FIG. 1;  
         [0030]    [0030]FIGS. 21A to  21 G are schematic view showing a first method as continued from FIG. 20E;  
         [0031]    [0031]FIGS. 22A to  22 F are schematic view showing a second method of manufacturing the yoke core of the magnetic head shown in FIG. 1;  
         [0032]    [0032]FIGS. 23A to  23 G are schematic views showing a second method as continued from FIG. 22F;  
         [0033]    [0033]FIGS. 24A to  24 F are schematic view showing a third method of manufacturing the yoke core of the magnetic head shown in FIG. 1;  
         [0034]    [0034]FIGS. 25A to  25 F are schematic views showing a third method as continued from FIG. 24F;  
         [0035]    [0035]FIGS. 26A to  26 G are schematic views showing a third method as continued from FIG. 25F;  
         [0036]    [0036]FIGS. 27A to  27 G are schematic views showing a fourth method for manufacturing a yoke core of a magnetic head shown in FIG. 1;  
         [0037]    [0037]FIGS. 28A to  28 D are schematic views showing a fourth method as continued from FIG. 27G;  
         [0038]    [0038]FIG. 29 is a perspective view showing an exemplary magnetic head device mounted with the magnetic head shown in FIG. 1; and  
         [0039]    [0039]FIG. 30 is a plan view showing an exemplary magnetic tape device having the magnetic head device shown in FIG. 29. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0040]    Preferred embodiments of the present invention will be explained hereinafter referring to the attached drawings.  
         [0041]    It should now be noted that although the specific embodiments described below, which are most preferable ones of the present invention, will be provided with various limitations in view of technical preference, the scope of the present invention is by no means limited thereto unless otherwise the description for limiting the present invention is specifically given.  
         [0042]    [0042]FIG. 1 is a perspective view showing an embodiment of a magnetic head fabricated in accordance with the present invention.  
         [0043]    A magnetic head  10  shown in FIG. 1 is a yoke-type thin-film MR head mounted on a rotating drum  4  rotating on a fixed drum  3  of a magnetic head device  2  of the helical scan system, with which a magnetic tape  1  is used as a recording medium.  
         [0044]    The magnetic head  10  comprises a yoke core  11  having a magnetic gap  11   a  exposed to the magnetic tape slide-contact plane, and an MR element or GMR element  12  formed on the yoke core  11  in an integrated manner therewith at the end opposite to such magnetic tape slide-contact plane; which are formed on a wafer substrate. The magnetic gap  11   a  of the yoke core  11  is formed so as to be aligned not in parallel to the wafer substrate plane (head moving direction), for example approximately perpendicular thereto.  
         [0045]    FIGS.  2  to  19  are schematic views showing a method of manufacturing the magnetic head  10  shown in FIG. 1. It should now be noted that some of the drawings show only an enlarged characteristic portion for easy recognition, so that dimensional ratios of individual components illustrated in these drawings do not always comply with the actual ratios.  
         [0046]    First, on a wafer substrate  20  made of highly abrasion-resistant calcium titanate (CaTiO 3 ) or AlTiC (alumina-titanium carbide) (Al 2 O 3 —TiC), a film  22  for forming yoke core groove comprising a chromium (Cr) film, a silicon dioxide (SiO 2 ) film and a chromium (Cr) film stacked in this order is formed using a sputtering apparatus (FIG. 2). The upper chromium (Cr) film is formed in a thickness of 100 nm, which is provided as an etching mask used when the silicon dioxide (SiO 2 ) film of 1.7 μm thick is anisotropically etched using a reactive ion etching (RIE) apparatus.  
         [0047]    The upper chromium (Cr) film has a selectivity with regard to the silicon dioxide film of 40 or above after an anisotropic etching, which is substitutable with an amorphous alloy film such as CoZrNb film.  
         [0048]    The lower chromium (Cr) film has a thickness of 50 nm, which is provided to limit the etching amount of the silicon dioxide (SiO 2 ) film and to relief the surface roughness of the wafer substrate  20  before it is fabricated into a head.  
         [0049]    Next, on the entire surface of the film  22 , an electron beam resist layer  23  (for example, ZEP 520(12), a product of Zeon Corporation) is formed by spin-coating at 2,000 rpm using a spin coating apparatus and cured, which is followed by drawing of a mask pattern  21  for forming the yoke core  11  using an electron beam drawing apparatus (FIG. 3).  
         [0050]    Next, the electron beam resist layer  23  is developed to thereby form the mask pattern  21 , and a portion of the upper chromium (Cr) film exposed in the opening of such mask pattern  21  is then etched with argon (Ar) ion using an ion etching apparatus, to thereby form a mask  22   a  having an opening for forming the yoke core  11  (FIG. 4).  
         [0051]    The mask  22   a  now has a split portion  22 A which is given so as to split a part of the portion for forming the magnetic gap  11   a  and so as to recess behind a level where a slide-contact plane with recording media is formed. A reason for forming the mask  22   a  having such split portion  22 A will be detailed later.  
         [0052]    Thereafter the electron beam resist layer  23  is removed, although being not always necessary. The mask  22   a  for forming the yoke core  11  now has a width d of the split portion  22 A (corresponding to the gap width) of, for example, 0.2 μm (FIG. 5).  
         [0053]    Next, a novolak-base, g-line resist layer  24  (for example, AZ-4400, a product of Hoechst AG) is formed by coating so as to cover the area other than the opening of the mask  22   a  for forming the yoke core  11 , and cured at 90 to 120° C. The novolak-base, g-line resist layer  24  is now patterned so as to have an opening larger by 1 to 10 μm than the opening of the mask  22   a  (FIG. 6). The novolak-base, g-line resist layer  24  is aimed at preventing polymer deposition which possibly inhibits the etching performed in the next process step using an RIE apparatus, and use thereof is optional.  
         [0054]    Next, the silicon dioxide (SiO 2 ) film exposed in the opening of the mask  22   a  for forming the yoke core  11  is anisotropically etched using an RIE apparatus until the lower chromium (Cr) film appears. Etching gas employed herein is a tetrafluorocarbon (CF 4 ) gas or a mixed gas of tetrafluorocarbon (CF 4 ) gas and oxygen (O 2 ), the etching power is set low so as to prevent undesirable temperature rise in the surface, and the etching time is set longer by approx. 10 to 20% than the time theoretically required for etching an SiO 2  film of 1.7 μm thick (FIG. 7). Since the etching stops on the surface of the lower chromium (Cr) film in the film  22 , the surface roughness of the wafer substrate  20  is reproduced. This is followed by removal of the novolak-base, g-line resist layer  24  (FIG. 8).  
         [0055]    Now a reason why the mask  22  is provided with the foregoing split portion  22 A will be discussed. During the etching using the RIE apparatus, the temperature of the mask  22   a  made of the chromium (Cr) film will gradually rise due to the exposure to the etching plasma. In particular for a case where the pattern width of the silicon dioxide film (SiO 2 ) is 0.3 μm or below, and the thickness to be etched amounts to 1 μm or above, the temperature of the mask  22   a  becomes considerably higher since the heat radiation will be expectable only from a limited area of silicon dioxide (SiO 2 ) just below the mask  22   a.    
         [0056]    Thus in the portion for forming the magnetic gap  11   a,  where the mask  22   a  has only a very small width, the upper chromium (Cr) film may deform due to heat expansion, and may even peel off from the silicon dioxide (SiO 2 ) film to thereby break in the worst case, which cannot serve as a mask any more. One possible measure for solving such problem relates to intermittent etching, in which a five-minute etching and three-minute cooling, for example, are alternated. This, however, results in that a larger part of the etching is proceeded in the fluctuating plasma, which makes it difficult to obtain the magnetic gap having an exact shape, and in particular to form the silicon dioxide (SiO 2 ) into a pattern having a width of 0.3 μm or below and a height of 1 μm or above, and which also makes it time-consuming.  
         [0057]    In the present invention, the mask  22   a  is formed so as to be partially split at the portion for forming the magnetic gap  11   a  to thereby have a discontinued structure, which successfully absorb the thermal expansion and thus prevents the upper chromium (Cr) film from being deformed, peeled-off from the silicon dioxide (SiO 2 ) and broken. Since the split portion  22 A is provided to the gap portion so as to recess behind a level where a slide-contact plane with recording media is formed, so that the split portion  22 A will not adversely affect a final product of the magnetic head  10  finished by surface grinding.  
         [0058]    Next, on the upper chromium (Cr) film and the lower chromium (Cr) exposed by the anisotropic etching, a magnetic layer  25  for forming the yoke core  11  is formed using a collimation apparatus, an RF-bias sputtering apparatus or a plating apparatus (FIGS. 9A and 9B). The magnetic layer  25  in this process step is formed in a predetermined thickness on the upper and lower chromium (Cr) layers as shown in FIG. 9B which is a sectional view taken along the line A-A in FIG. 9A. The top surface of the magnetic layer  25  is then planarized by polishing using a buffing machine to have the yoke core  11  to be a predetermined thickness, typically to 1.5 μm (FIGS. 10A and 10B).  
         [0059]    Next, on the entire surface of the film  22  and the yoke core  11 , an insulating film  26  made of silicon dioxide (SiO 2 ) or aluminum oxide (Al 2 O 3 ), which is provided for ensuring insulation between the yoke core and the MR element or GMR element  12 , is formed using a sputtering apparatus. The top surface of the insulating film  26  is then planarized by polishing using a buffing machine (FIG. 11), and the MR element or GMR element  12  is formed on the yoke core  11  at the end opposite to the magnetic tape slide-contact plane (FIG. 12).  
         [0060]    Next, the a first electrode  27   a  and a second electrode  27   b  are formed based on sputtering and the successive lift-off processes, and terminals  28  individually connected thereto are formed using a plating apparatus. A layout of the first electrode  27   a,  second electrode  27   b  and terminals  28  is such that shown in FIGS. 13, 14 and  15 , all of which showing an entire portion of the wafer substrate  20 . The description below relates to the entire portion of the wafer substrate  20 .  
         [0061]    Next, a protective layer  29  made of silicon dioxide (SiO 2 ) or aluminum oxide (Al 2 O 3 ) is formed using an RF-bias sputtering apparatus on the entire surface of the film  22 , the MR element or GMR element  12 , the first electrode  27   a,  the second electrode  27   b,  and the terminals  28  (FIG. 16). The top surface of the protective layer  29  is then planarized by polishing using a mechanical polishing machine to thereby expose the top surface of the terminals  28  and ensure the entire flatness (FIG. 17).  
         [0062]    In the final step, on the protective layer  29  and within a portion over the MR element or GMR element  12 , an upper guard member  20 G made of calcium titanate (CaTiO 3 ) or AlTiC (alumina-titanium carbide) (Al 2 O 3 —TiC) is adhered (FIG. 18), and the magnetic tape slide-contact plane is finished using a cylindrical polishing machine, to thereby complete the final product of the magnetic head  10  (FIG. 19).  
         [0063]    While the above embodiment dealt with the yoke-type thin-film MR head, the present invention is by no means limited thereto, and is applicable also to an inductive head in which a core aligned in parallel to the major plane of the wafer substrate  20  and an electro-magnetic conversion coil are integrated with the yoke core  11 , or to a recording/reproducing magnetic head integrated therewith. Also the method of manufacturing the yoke core  11  is not limited to that described in the above, and instead the methods described below are also allowable.  
         [0064]    [0064]FIGS. 20A to  21 F are schematic views showing a first method for manufacturing the yoke core  11 , in which the magnetic gap  11   a  is provided perpendicular to a wafer substrate  30 .  
         [0065]    First, on the entire surface of the wafer substrate  30  a magnetic layer  31  is formed using a sputtering apparatus (FIG. 20A), and on the magnetic layer  31  a resist layer  32  for forming a magnetic portion  131  corresponding to one half of the yoke core  11  is formed using a printing machine, and then cured (FIGS. 20B and 20C). The exposed portion of the magnetic layer  31  is then etched using an ion etching apparatus (FIGS. 20D and 20E), and the resist layer  32  is removed to thereby form the magnetic portion  131  as the one half of the yoke core  11  (FIGS. 21A and 21B).  
         [0066]    Next, on the magnetic portion  131  as the one half of the yoke core  11  and the wafer substrate  30 , a gap layer  33  is formed using a sputtering apparatus (FIG. 21C), and further thereon, a magnetic layer  34  is formed using a sputtering apparatus (FIG. 21D).  
         [0067]    Then the top surface of the magnetic layer  34  is planarized by polishing using a mechanical polishing machine, where the gap layer  33  is locally removed in a portion on the top surface of the magnetic portion  131  as the one half of the yoke core  11  (FIG. 21E). Then the magnetic portion  131  as the one half of the yoke core  11 , the gap layer  33  and the magnetic layer  34  are patterned using an ion etching apparatus to thereby form an outline portion  132  of the yoke core  11  (FIG. 21F).  
         [0068]    In the final step, an insulating layer  35  is formed on the entire surface of the wafer substrate  30  so as to fully cover the outline portion  132  of the yoke core  11 , and a top surface of the insulating layer  35  is then planarized by polishing using a mechanical polishing machine until the thickness of the outline portion  132  is reduced to a predetermined value (FIG. 21G). Such processes successfully provide the yoke core  11 .  
         [0069]    [0069]FIGS. 22A to  23 G are schematic views showing a second method for manufacturing the yoke core  11 , in which the magnetic gap  11   a  is provided inclined to a wafer substrate  40 .  
         [0070]    First, on the entire surface of the wafer substrate  40  a magnetic layer  41  is formed using a sputtering apparatus (FIG. 22A), and on the magnetic layer  41 , a resist layer  42  for forming a magnetic portion  141  corresponding to one half of the yoke core  11  is formed using a printing machine, and then cured to thereby produce a mesa-formed pattern (FIGS. 22B, 22C and  22 D). The exposed portion of the magnetic layer  41  is then etched using an ion etching apparatus (FIG. 22E), to thereby form a mesa-formed magnetic portion  141  as the one half of the yoke core  11  (FIG. 22G).  
         [0071]    Next, the resist layer  42  is removed (FIGS.  23 A and  23 B), and a gap layer  43  is formed using a sputtering apparatus on the magnetic portion  141  as the one half of the yoke core  11  and the wafer substrate  40  (FIG. 23C), and further thereon, a magnetic layer  44  is formed using a sputtering apparatus (FIG. 23D).  
         [0072]    Then the top surface of the magnetic layer  44  is planarized by polishing using a mechanical polishing machine, where the gap layer  43  is locally removed in a portion on the top surface of the magnetic portion  141  as the one half of the yoke core  11  (FIG. 23E). Then the magnetic portion  141  as one half of the yoke core  11 , the gap layer  43  and the magnetic layer  44  are patterned using an ion etching apparatus to thereby form an outline portion  142  of the yoke core  11  (FIG. 23F).  
         [0073]    In the final step, an insulating layer  45  is formed on the entire surface of the wafer substrate  40  so as to fully cover the outline portion  142  of the yoke core  11 , and a top surface of the insulating layer  45  is then planarized by polishing using a mechanical polishing machine until the thickness of the outline portion  142  is reduced to a predetermined value (FIG. 23G). Such processes successfully provide the yoke core  11 .  
         [0074]    [0074]FIGS. 24A to  26 G are schematic views showing a third method for manufacturing the yoke core  11 .  
         [0075]    First, on a wafer substrate  50 , a film  51  comprising a chromium (Cr) film, a silicon dioxide (SiO 2 ) film and a chromium (Cr) film stacked in this order is formed using a sputtering apparatus (FIG. 24A), and further thereon, a resist layer  52  is formed using a printing machine and then cured to thereby produce a mask used for processing one half of the yoke core  11  (FIG. 24B).  
         [0076]    The exposed portion of the upper chromium (Cr) film in the film  51  is then etched using an ion etching apparatus, and then the exposed silicon dioxide (SiO 2 ) film is anisotropically etched until the lower chromium (Cr) layer exposes (FIG. 24C). The resist layer  52  is then removed to thereby produce a film portion  151  for forming the yoke core  11  (FIGS. 24D and 24E).  
         [0077]    Next, on the wafer substrate  50  and the film portion  151 , a magnetic layer  53  is formed using a sputtering apparatus (FIG. 24F), and a top surface of the magnetic layer  53  is then planarized by polishing using a mechanical polishing machine until a top surface of the film portion  151  exposes (FIGS. 25A and 25B). Then the magnetic layer  53  around the film portion  151  is removed using a wet etching apparatus, to thereby form a magnetic portion  153 , as the one half of the yoke core  11 , as being surrounded by the film portion  151  (FIGS. 25C and 25D).  
         [0078]    Next, on the wafer substrate  50 , the film portion  151  and the magnetic portion  153 , a resist layer  54  is formed using a printing machine and cured, to thereby produce a mask used for processing the other half of the yoke core  11  (FIG. 25E), and the exposed portion of the film portion  151  is then anisotropically etched using an RIE apparatus (FIG. 25F). The resist layer  54  is then removed (FIGS. 26A and 26B), a gap layer  55  is formed on the wafer substrate  50 , the film portion  151  and the magnetic portion  153  using a sputtering apparatus (FIGS. 26C and 26D), and further thereon a magnetic layer  56  is formed (FIG. 26E).  
         [0079]    In the final step, a top surface of the magnetic layer  56  is planarized by polishing using a mechanical polishing machine until the top surfaces of the film portion  151  and the magnetic portion  153  appear, to thereby form a magnetic portion  253  as the other half of the yoke core  11  surrounded by the film portion  151  (FIG. 26F). The magnetic layer  56  surrounding the film portion  151  is then removed using a wet etching apparatus, to thereby form the yoke core  11  (FIGS. 26G and 26H).  
         [0080]    [0080]FIGS. 27A to  28 D are schematic views showing a fourth method for manufacturing the yoke core  11 .  
         [0081]    First, on a wafer substrate  60 , a film  61  comprising a silicon dioxide film (SiO 2 ) and a chromium (Cr) film stacked in this order is formed using a sputtering apparatus (FIG. 27A), and on approximately half area of a surface of such film  61 , a resist layer  62  is formed using a printing machine and then cured to thereby produce a mask used for processing the gap  11   a  of the yoke core  11  (FIG. 27B).  
         [0082]    The exposed portion of the film  61  is then etched using an etching apparatus (FIG. 27C), a gap layer  63  is formed on the wafer substrate  60  and the resist layer  62  using a sputtering machine (FIG. 27D). A portion of the gap layer  63  on the resist layer  62  is then removed together with such resist layer  62  by the lift-off process (FIG. 27E), and the film  61  and the horizontal portion, other than the vertical central portion, of the gap layer  62  is then anisotropically etched using an RIE apparatus (FIG. 27F).  
         [0083]    Next, a magnetic layer  64  is formed on the wafer substrate  60  and the gap layer  63  using a sputtering apparatus (FIG. 27G), a top surface of such magnetic layer  64  is then etched using an ion etching apparatus (FIGS. 28A and 28B). The magnetic layer  64  is then patterned to produce a magnetic portion  164  having a shape of the yoke core  11  (FIG. 28C).  
         [0084]    In the final step, an insulating layer  67  is formed on the wafer substrate  60  and the magnetic portion  164  using a sputtering apparatus, and a top surface of such magnetic layer  67  is planarized by polishing using a mechanical polishing machine until the top surface of the magnetic portion  164  exposes (FIG. 28D), to thereby produce the yoke core  11 .  
         [0085]    [0085]FIG. 29 is a perspective view showing an exemplary magnetic head device mounted with the magnetic head according to the embodiment of the present invention, and FIG. 30 is a plan view showing an exemplary magnetic tape device having such magnetic head device.  
         [0086]    The magnetic head device  70  has a fixed drum  71 , a rotating drum  72 , a motor M and so forth, which refers to a rotating magnetic head device mounted to a magnetic tape device based on the helical scan system using a magnetic tape TP as an information recording medium. A magnetic tape device  80  is an information recording/reproducing device having the magnetic head device  70  therein.  
         [0087]    As shown in FIG. 29, the rotating drum  72  is provided with a reproducing head  10  and a recording head  10 R located at a phase difference of 180° . The rotating drum  72  rotates with the aid of the motor M in the direction indicated by the arrow R relative to the fixed head  71 .  
         [0088]    The magnetic tape TP is fed aslant from the entrance side IN, along the moving direction E as being guided by a lead guide portion  73  of the fixed drum  71  toward the exit side OUT. That is, as shown in FIG. 30, the magnetic tape TP is fed out from a supply reel  81 , guided by rollers  82   a,    82   b  and  82   c,  traverses on the fixed drum  71  in contact therewith over an angular range of approx. 180° as being guided by lead guide portion  73  thereof, and is further guided by rollers  82   d,    82   e,    82   f  and  82   g  to be taken up by a take-up reel  83 .  
         [0089]    Thus the reproducing head  10  and the recording head  10 R traces on the magnetic tape TP according to the helical scan system. A capstan  82   h  is opposed to the roller  82   f,  and is rotated with the aid of a capstan motor M 1 .  
         [0090]    Although the invention has been described in its preferred form with a certain degree of particularity, obviously many changes and variations are possible therein. It is therefore to be understood that the present invention may be practiced otherwise than as specifically described herein without departing from the scope and the sprit thereof.  
         [0091]    For example, the present invention is not limited to the foregoing embodiment which dealt with an application to the magnetic head device based on the helical scan system, and is applicable to other types of the magnetic head device based on a fixed system allowing a high-speed sliding or flotation system.