Patent Document

CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a divisional application of U.S. patent application Ser. No. 09/755,728, filed Jan. 5, 2001. This application also claims the benefit of U.S. Provisional Patent Application Serial Nos. 60/174,459 and 60/174,584 both filed Jan. 5, 2000. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates to magnetic recording heads for use with magnetic recording media. More specifically, the invention relates to the structure and method of manufacturing for a coil within such a recording head.  
         BACKGROUND OF THE INVENTION  
         [0003]    Recording heads for use with magnetic recording media typically include a pair of magnetically coupled poles, consisting of a main write pole and an opposing pole. The main pole may have a significantly smaller surface area on its bottom surface than the opposing pole. A coil is located adjacent to the main pole for inducing a magnetic field in the main pole. Magnetic recording media used with such recording heads typically includes a recording layer having alternating magnetically hard tracks and nonmagnetized transitions. If perpendicular recording is desired, a magnetically soft lower layer will typically be located adjacent to the recording layer, opposite the recording head.  
           [0004]    The recording density is inversely proportional to the width of the magnetically hard recording tracks. Trackwidth is primarily determined by the width of the main write pole, which is limited by the various manufacturing processes used to produce such poles. Additionally, the efficiency of the coil structure in inducing magnetic flux within the poles affects the performance of the recording head.  
           [0005]    Therefore, there is a need for an improved recording head having a main pole that can be manufactured to narrow widths. Additionally, there is a need for a recording head having a coil structure maximizing the efficiency of inducing magnetic flux in the poles.  
         SUMMARY OF THE INVENTION  
         [0006]    The invention is a recording head for use with magnetic recording media, and an improved method of manufacturing such a head. Although not limited to such use, such a recording head is particularly useful for fixed or hard drives for computers.  
           [0007]    Recording heads made in accordance with this invention include a read portion and a write portion. The write portion may be of either perpendicular or longitudinal configuration. A typical perpendicular recording head includes a main pole, an opposing pole magnetically coupled to the main pole, and an electrically conductive coil adjacent to the main pole. The bottom of the opposing pole will typically have a surface area greatly exceeding the surface area of the main pole&#39;s tip. Likewise, a typical longitudinal recording head includes a pair of poles, with a coil adjacent to one pole. Unlike a perpendicular recording head, a longitudinal recording head will typically use poles having bottom surfaces with substantially equal areas. In either case, electrical current flowing through the coil creates a flux through the main pole. The direction of the flux may be reversed by reversing the direction of current flow through the coil. In some preferred embodiments, the opposing pole of the perpendicular head (or the first pole of the longitudinal head) can also form one of two substantially identical shields for the read element, located between these two shields. The read element will preferably be either a GMR read element or a spin valve.  
           [0008]    The write structure of the present recording head uses only inorganic insulators, for example, alumina, which may be vacuum deposited. The use of inorganic insulators also prevents the necessity of using a hard bake process, as would be necessary to cure an organic insulator. Such hard bake processes will degrade a typical GMR read sensor. Additionally, such processes cause expansion and contraction of the various components of the recording head, thereby possibly causing cracking due to the resulting stresses. Additionally, the present recording head places the writing pole on a very flat surface, thereby facilitating greater control of the spinning process used to deposit the photoresist for defining the main pole. Depositing such photoresist in a more controlled manner, providing a more uniform thickness of photoresist, permits the write pole to be plated or deposited in a manner dimensioned and configured to conform to submicron track widths.  
           [0009]    A preferred method of manufacturing a recording head of the present invention begins with a read sensor deposited between a pair of shields, with the entire structure deposited on a substrate in the conventional manner. The read sensor may preferably be a GMR read element or a spin valve. After chemical-mechanical polishing the surface of the combined shield and opposing write pole, the write gap (preferably alumina) is deposited on top of this shield. Next, photoresist shielding is deposited on top of the opposing pole/shield and write gap, leaving exposed the area where the coil will be deposited. Next, the coil (preferably copper) is deposited on the write gap. If desired, the photoresist shielding may be removed at this point, and replaced with photoresist shielding defining a slightly larger opening around the coil. Insulation (preferably alumina) is then deposited on top of the coil, with the larger opening in the photoresist ensuring that all surfaces of the coil are covered. The photoresist shielding is then removed, and the main write pole is deposited on top of the insulation and write gap, with the top portion of the write pole magnetically coupled to the opposing pole/shield.  
           [0010]    An alternative method of manufacturing the recording head also begins with chemical-mechanical polishing of the surface of the opposing write pole, which also forms one of the two shields for the read sensor. A layer of material forming the insulation is deposited on this surface, followed by the material forming the coil, which is in turn followed by material forming the opposite layer of insulation. Photoresist shielding is then applied to the second layer of insulation, over that portion of the insulation and coil which will remain part of the final recording head. The undesired portions of the coil and insulation material are then ion milled away, with the ion milling conducted at an angle so that the remaining portion is tapered, with the widest portion adjacent to the opposing pole. The photoresist shielding is then removed, and the write gap is deposited on top of the second layer of insulation, coil, and shield/opposing write pole. The main write pole is then deposited on top of the write gap, and magnetically coupled to the top of the opposing write pole/shield.  
           [0011]    A typical magnetic recording medium includes a first layer having a plurality of magnetically permeable tracks separated by nonmagnetized transitions. The tracks are further subdivided into sectors. If perpendicular recording is desired, the magnetic recording medium will include a magnetically permeable lower level. The lower level is magnetically soft relative to the tracks.  
           [0012]    The recording head is separated from the magnetic recording medium by a distance known as the flying height. The magnetic recording medium is moved past the recording head so that the recording head follows the tracks of the magnetic recording medium, with the main pole oriented parallel to the tracks and perpendicular to the trackwidth. Current is passed through the coil to create magnetic flux within the main pole. The flux will cause the magnetic fields in the tracks to align with the magnetic flux of the main pole (in the case of perpendicular recording) or the write gap (in the case of longitudinal recording). Changing the direction of electric current changes the direction of the flux created by the recording head and therefore the magnetic fields within the magnetic recording medium. A binary “zero” is recorded by maintaining a constant direction of magnetic flux through the main pole, and a binary “one” is recorded by changing the direction of magnetic flux through the main pole.  
           [0013]    It is therefore an aspect of the present invention to provide a recording head wherein all insulating materials are inorganic.  
           [0014]    It is another aspect of the present invention to avoid the necessity of using a hard bake process in manufacturing a recording head.  
           [0015]    It is another aspect of the present invention to provide a recording head wherein the read element is protected from damage caused by heat during manufacturing.  
           [0016]    It is another aspect of the present invention to provide a recording head free from thermally induced stresses.  
           [0017]    It is a further aspect of the present invention to provide a recording head with a coil having an efficient flux path.  
           [0018]    It is another aspect of the present invention to provide a recording head wherein the surface upon which the main write pole is deposited is kept flat, thereby permitting uniform deposition of narrower write poles.  
           [0019]    These and other aspects of the present invention will become more apparent through the following description and drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1 is a top view of a typical hard disc drive for a computer for which the present invention may be used, illustrating the disc drive with its upper housing portion removed.  
         [0021]    [0021]FIG. 2 is a partially sectioned, partially schematic, isometric view of an embodiment of a recording head according to the present invention.  
         [0022]    [0022]FIG. 3 is a cross-sectional side view of a recording head according to the present invention.  
         [0023]    [0023]FIG. 4 is a bottom view of a recording head according to the present invention.  
         [0024]    [0024]FIG. 5 is a cross-sectional side view of a substrate, shields and read element for a recording head according to the present invention.  
         [0025]    [0025]FIG. 6 is a cross-sectional side view of a substrate, shields, read elements and write gap for a recording head according to the present invention.  
         [0026]    [0026]FIG. 7 is a cross-sectional side view of a substrate, shields, read element, and write gap for a recording head according to the present invention, after application of photoresist.  
         [0027]    [0027]FIG. 8 is a cross-sectional side view of a substrate, shields, read elements, write gap, and deposited coil material for a recording head according to the present invention.  
         [0028]    [0028]FIG. 9 is a cross-sectional side view of a shields, write gap, and deposited coil material for a recording head according to the present invention.  
         [0029]    [0029]FIG. 10 is a cross-sectional side view of a substrate, shields, read elements, write gap, and coil of a recording head of the present invention, after removal of photoresist shielding.  
         [0030]    [0030]FIG. 11 is a cross-sectional side view of a substrate, shields, read element, write gap, and coil of a recording head of the present invention, after application of photoresist shielding.  
         [0031]    [0031]FIG. 12 is a cross-sectional side view of a substrate, shields, read sensor, coil, and deposited insulation material for a recording head according to the present invention.  
         [0032]    [0032]FIG. 13 is a cross-sectional side view of a substrate, shields, read element, write gap, coil and insulation for a recording head according to the present invention, after removal of the photoresist shielding.  
         [0033]    [0033]FIG. 14 is a cross-sectional side view of an alternative embodiment of a recording head according to the present invention.  
         [0034]    [0034]FIG. 15 is a cross-sectional side view of a substrate, shields, and read element for an alternative recording head according to the present invention.  
         [0035]    [0035]FIG. 16 is a cross-sectional side view of a substrate, shields, read element, coil, and coil insulation for an alternative recording head according to the present invention.  
         [0036]    [0036]FIG. 17 is a cross-sectional side view of a substrate, shields, read element, coil and coil insulation for an alternative recording head according to the present invention, after application of photoresist shielding.  
         [0037]    [0037]FIG. 18 is a cross-sectional side view of a substrate, shields, read element, coil, and insulation for an alternative recording head of the present invention, following removal of unnecessary coil and insulation material.  
         [0038]    [0038]FIG. 19 is a cross-sectional side view of a substrate, shields, read element, coil, and insulation for an alternative recording head according to the present invention, after removal of the photoresist shielding.  
         [0039]    [0039]FIG. 20 is a cross-sectional side view of a substrate, shields, read element, coil, insulation, and write gap for an alternative recording head according to the present invention. 
     
    
       [0040]    Like reference numbers denote like elements throughout the drawings.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0041]    The preferred embodiments of the present invention are recording heads for use with magnetic recording media, which may be configured for longitudinal or perpendicular recording. Although not limited to such use, such a recording head is particularly useful for fixed or hard drives for computers. As used herein, recording head is defined as a head adapted for read and/or write operations, although the present invention is specifically directed towards the write portion of the recording head.  
         [0042]    The invention will most commonly be used within a fixed disc drive  10  for computers, one of which is illustrated in FIG. 1. The fixed disc drive  10  includes a housing  12  (with the upper portion removed and the lower portion visible in this view for maximum clarity) dimensioned and configured to contain and locate the various components of the disc drive  10 . The disc drive  10  includes a spindle motor  14  for rotating at least one magnetic storage medium  16  within the housing, in this case a magnetic disc. At least one arm  18  is contained within the housing  12 , with each arm  18  having a first end  20  with a recording head or slider  22 , and a second end  24  pivotally mounted to a bearing  26 . An actuator motor  28 , such as a movable coil DC motor, is located at the arm&#39;s second end  24 , pivoting the arm  18  to position the head  22  over a desired sector of the disc  16 . The actuator motor  28  is regulated by a controller which is not shown and which is well known.  
         [0043]    Referring to FIGS. 2, 3,  4 , and  14 , the features of the recording head  22  are illustrated. The recording head  22  includes means for concentrating magnetic flux onto a small surface area of the magnetic recording media, here a magnetically permeable main pole  30 , oriented substantially perpendicular to the magnetic recording medium  16 , and having a tip  32 . The tip  32  includes a bottom surface  34 . The top  36  of the main pole  30  is preferably magnetically coupled to an opposing pole  38 , possibly through a joint  40 . The opposing pole  38  includes a bottom surface  42 . If perpendicular recording is desired, then the bottom surface  42  will have a surface area significantly larger than the surface area of the bottom surface  34  of the main pole  30 . If longitudinal recording is desired, then the bottom surfaces  34  and  42  may have substantially identical areas. An electrically conductive coil  44  is located adjacent to the main pole  30 , and is dimensioned and configured to induce a magnetic flux in the main pole  30 . The coil  44  is surrounded by insulation  46 , which in the present invention is made from inorganic material. A preferred and suggested material for the insulation  46  is alumina.  
         [0044]    Located adjacent to opposing pole  38 , opposite the main pole  30  and coil  44 , is a read element  48 . The read element  48  is preferably a GMR read element or spin valve, operating in conjunction with electrical contacts  50  located on opposing sides of the read element  48 . If the read element  48  is a GMR read element, a permanent magnet  52  may be located above the read element  48 . The read element  48  is located between a pair of opposing shields. In some preferred embodiments, the opposing pole  38  may form one of the two magnetic shields. The other shield  58  is located on the opposite side of the read element  48 . The entire recording head  22  is built up on a surface  54  of a substrate  56 .  
         [0045]    One alternative method of making a recording head according to the present invention is illustrated in FIGS.  5 - 13 . As illustrated in FIG. 5, the method begins by providing a substrate  56  upon which the read element  48  and its associated shields  38  and  58  have already been deposited. The surface  60  of shield/pole  38  is chemical-mechanical polished to ensure that it is flat. The write gap  62 , which forms a part of the insulation  46 , is deposited on the surface  60  of pole  38 . A preferred material for the write gap is alumina. A first photoresist shield  64  is applied over the write gap  62 , as illustrated in FIG. 7, thereby defining the eventual size and location of the coil  44 . The material forming the coil, preferably copper, is deposited as illustrated in FIGS. 8 and 9. This material may be deposited either perpendicular to the write gap  62 , or at an angle to the write gap  62 , to produce an appropriately dimensioned and configured coil  44  within the gap  66  defined by the photoresist  64 . At this point, the first photoresist  64  may be removed as illustrated in FIG. 10, for replacement with a second photoresist shield  68  defining an opening  70  larger than the opening  66  in the first photoresist  64  (FIG. 11), or the original photoresist  64  may simply be left in place. Referring to FIG. 12, a layer of insulation material  72  is deposited over the coil  44  and photoresist  64  or  68 . The photoresist  64  or  68  is removed as illustrated in FIG. 13. The use of these deposition procedures has now defined a surface  74  having a very flat surface area. Referring back to FIG. 3, the write pole  30  is deposited on top of the surface  74 . The flat surface  74  permits the photoresist that will ultimately define the width of the write pole  30  to be spinned into place in a more controlled manner, thereby permitting a small write pole to be produced without compromising the pole&#39;s magnetic properties.  
         [0046]    An alternative procedure for making a write pole of the present invention is illustrated in FIGS.  14 - 20 . As before, the process begins by providing a substrate  56  having a read element  48  and its associated shields  38  and  58  secured to the substrate surface  54 . The surface  60  is chemical-mechanical polished to ensure that it is flat. These components are illustrated in FIG. 15. Referring to FIG. 16, a first layer of insulation  76  (preferably alumina) is deposited on the surface  60 , followed by the material forming the coil  44  (preferably copper), and a second layer of insulation  78 . A photoresist shield  80  is then deposited over the second layer of insulation  78 , thereby protecting those portions of the insulation layers  76  and  78  that will remain, and that portion of the coil  44  that will remain. The photoresist  80  has also thereby defined the excess material  82  to be removed in subsequent steps. This excess material  82  is removed as illustrated in FIG. 18. A preferred method of removing the excess material  82  is by ion milling, which may be performed at an angle. Preferably, the angle is selected so that the remaining coil and insulation assembly  98  is tapered, with the area of the surface  84 , adjacent to the photoresist (and eventually the main pole  30 ) being smaller than the area of the surface  86  adjacent to the shield and opposing pole  38 . The arrows B indicate a preferred direction for the milling process. Photoresist  80  may then be removed as illustrated in FIG. 19, and write gap  62  may be deposited as illustrated in FIG. 20. These deposition processes define a surface  88  on the write gap  62 , with the surface  88  preferably having flat surface topology. Referring back to FIG. 14, the flat surface  88  permits the photoresist that will ultimately define the width of the write pole  30  to be spinned into place in a more controlled manner, thereby permitting a small write pole to be produced without compromising the pole&#39;s magnetic properties.  
         [0047]    Referring back to FIG. 2, a magnetic storage medium  16 , here a magnetic disc, for use with a perpendicular recording head  22  is illustrated. The disc  16  includes a recording layer  90  having a plurality of magnetically permeable tracks  92 , which are divided into sectors. Each sector has several different magnetic fields within the magnetically permeable material (not shown and well understood). The tracks  92  are separated by nonmagnetized transitions  94 . If perpendicular recording is desired, then the disc  16  also includes a magnetically permeable lower layer  96 , which is magnetically soft relative to the tracks  92 . In use, the disc  16  will be separated from the tip  32  of the main pole  30  by a flying height A. The flying height A is sufficiently small so that a high concentration of flux from the main pole  30  will pass through the track  92 , but sufficiently large to prevent damage to disc  16  from contact with the recording head  22 .  
         [0048]    Recording is accomplished by rotating the disc  16  relative to the recording head  22  so that the recording head  22  is located above the appropriate sectors of the tracks  92 . As recording progresses, the disc  16  will move past the recording head  22 . Current will be supplied to the coil  44 , thereby inducing a magnetic field within the main pole  30 . As a portion of the sector of the track  92  passes under the main pole  30 , the orientation of its magnetic field will correspond to the orientation of the magnetic field of the main pole  30  in the case of perpendicular recording, or the orientation of the magnetic field within the write gap in the case of longitudinal recording. As the main pole passes over the disc  16 , the direction of current passing through the coil  44  will remain constant when a binary “0” is being recorded, thereby creating consistent orientation of the magnetic fields within the track  92 . The current passing through the coil  44  will reverse directions when a binary “1” is being recorded, thereby changing the orientation of a magnetic field within the track  92 .  
         [0049]    The recording density possible with a perpendicular recording head is primarily dependent upon the main pole&#39;s width C. The width C required is determined by the precision with which the deposition or plating process used to deposit the write pole  30  can be accomplished. This precision is affected by the flatness of either surface  74  or surface  88 , upon which the write pole  30  will be plated. It is well known in the art that a photoresist will be used to define the area upon which the main pole  30  will be plated or sputtered, and that this photoresist is applied by a spinning process with the photoresist in liquid form. The spinning process can be controlled more precisely if applied to a flat surface. Therefore, maximizing the flatness of the surface area  72  or  88  minimizes the area upon which the write pole  30  must be deposited to ensure that the proper magnetic properties are present, thereby minimizing the width C of the write pole and maximizing recording density.  
         [0050]    Additionally, because all electrically insulating materials used within a recording head  22  of the present invention are inorganic, and preferably vacuum deposited, a thermally efficient, low stress structure results. The hard bake process is typically used to cure organic insulators are avoided, freeing the read sensor from degradation caused by these processes. Additionally, the hard bake process causes the components of the recording head  22  to expand and contract, resulting in thermal stresses and possibly cracks.  
         [0051]    The present invention has the additional advantage of keeping the path for the magnetic field around the coil  44  as simple as possible. The distance from the bottom surface  34  to the top of the coil may be less than 2 microns.  
         [0052]    While a specific embodiment of the invention has been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any and all equivalents thereof.

Technology Category: y