Abstract:
Methods of fabricating magnetic read heads are provided which reduce the width of the scratch exposure region of a read head. During normal fabrication processes, a read head is formed with a first shield, a read element formed on the first shield, and hard bias layers formed on either side of the read element. The width of the read elements and the hard bias layers define an initial scratch exposure region. According to embodiments herein, a mask structure is formed to protect the read element and first portions of the hard bias layers proximate to the read element. A removal process is then performed to remove second portions of the hard bias layers that are not protected by the mask structure, which defines a final scratch exposure region that is smaller than the initial scratch exposure region.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention is related to the field of magnetic recording disk drive systems and, in particular, to fabricating a magnetic read heads with a reduced scratch exposure region. 
         [0003]    2. Statement of the Problem 
         [0004]    Magnetic hard disk drive systems typically include a magnetic disk, a recording head having write and read elements, a suspension arm, and an actuator arm. As the magnetic disk is rotated, air adjacent to the disk surface moves with the disk. This allows the recording head (also referred to as a slider) to fly on an extremely thin cushion of air, generally referred to as an air bearing. When the recording head flies on the air bearing, the actuator arm swings the suspension arm to place the recording head over selected circular tracks on the rotating magnetic disk where signal fields are written to and read by the write and read elements, respectively. The write and read elements are connected to processing circuitry that operates according to a computer program to implement write and read functions. 
         [0005]    In a disk drive, particles are often generated within the disk enclosure. Occasionally, these particles are drawn between the magnetic disk and an air bearing surface of the read head. As these particles are squeezed between the read head and the magnetic disk, a small amount of mechanical deformation may occur on the read head. Typically, this mechanical deformation occurs across elements of the read head that are not significantly affected by the deformation. Thus, the mechanical deformation does not affect subsequent performance of the read head. However, if the deformation is across the read gap of the read head where two leads (e.g., two shields) are separated by a very thin insulating gap, then metallic material can be smeared across the read gap. The likelihood of smearing depends on the size of the gap between the two shields. The size of the gap between the shields is often reduced by the addition of hard bias magnets between the shields on either side of the read element. Smears of metallic material between the two shields may permanently degrade the performance of the read head. The area of a read head that is susceptible to smearing between the shields is referred to as the scratch exposure region. 
         [0006]    It is therefore desirable to reduce the scratch exposure region so that shorting of the leads is less likely. One way of decreasing the scratch exposure region is to minimize the track width of the read element and to minimize the size of the hard bias magnets on either side of the read element. Unfortunately, there are limitations in present lithographic fabrication processes, such as mask alignment and sizing issues, which restrict decreasing the size of these components during their formation. Thus, it is a problem for manufacturers of read heads to adequately decrease the size of the scratch exposure region of the read heads. 
       SUMMARY OF THE SOLUTION 
       [0007]    Embodiments of the invention solve the above and other related problems with methods of fabricating CPP read heads to reduce the width of the scratch exposure region. During normal fabrication processes, a read head is formed with a first shield, a read element formed on the first shield, and hard bias layers formed on either side of the read element. The width of the read elements and the hard bias layers define an initial scratch exposure region. According to embodiments herein, a mask structure is formed to protect the read element and first portions of the hard bias layers proximate to the read element. A removal process is then performed to remove second portions of the hard bias layers that are not protected by the mask structure. This removal process defines a final scratch exposure region that is smaller than the initial scratch exposure region. Because the final scratch exposure region is reduced, it less likely that there will be a short in the read head due to a scratch. 
         [0008]    One embodiment of the invention comprises a method of reducing the scratch exposure region of a read head. The read head includes a first shield, a read element formed on the first shield, and hard bias layers formed on either side of the read element. According to the method, a mask structure is formed to protect the read element and first portions of the hard bias layers proximate to the read element. A removal process is then performed, such as a milling process, to remove second portions of the hard bias layers that are not protected by the mask structure. Insulating material is then deposited and the mask structure is removed. This process results in a read head where the width of the read element and the remaining first portions of the hard bias layers is much less than the width of the read element and the original hard bias layers. The scratch exposure region is thus reduced. 
         [0009]    Another embodiment of the invention comprises another method of fabricating a read head. One step of the method includes fabricating a read element and hard bias layers on side regions of the read element. The width of the read element and the hard bias layers define an initial scratch exposure region. Another step includes forming a mask structure on the read element and portions of the hard bias layers proximate to the read element. Another step includes performing a removal process to remove portions of the hard bias layers that are not protected by the mask structure. The width of the read element and the remaining hard bias layers after the removal process define a final scratch exposure region that is smaller than the initial scratch exposure region. Other steps include depositing insulating material, and removing the mask structure. 
         [0010]    The invention may include other exemplary embodiments described below. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0011]    The same reference number represents the same element or same type of element on all drawings. 
           [0012]      FIG. 1  illustrates a typical CPP read head in the prior art. 
           [0013]      FIG. 2  illustrates a read head during fabrication in the prior art. 
           [0014]      FIG. 3  is a flow chart illustrating a method of fabricating a read head with a reduced scratch exposure region in an exemplary embodiment of the invention. 
           [0015]      FIGS. 4-7  illustrate a read head formed during fabrication according to the method of  FIG. 3  in exemplary embodiments of the invention. 
           [0016]      FIG. 8  is a flow chart illustrating a further method of fabricating a read head with a reduced scratch exposure region in an exemplary embodiment of the invention. 
           [0017]      FIGS. 9-12  illustrate a read head formed during fabrication according to the method of  FIG. 8  in exemplary embodiments of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]      FIG. 1  illustrates a typical CPP read head  100 . The view in  FIG. 1  is from the Air Bearing Surface (ABS) side of read head  100 . Read head  100  includes a first shield  102  with a magnetoresistance (MR) read element  104  formed on the first shield  102 . Read head  100  further includes hard bias layers  110 - 111  that are formed on the sides of read element  104 . The hard bias layers  110 - 111  are separated from read element  104  and the first shield  102  by insulating layers  106 - 107 . Read head  100  further includes refill material  114 - 115  and gap fill material  118 - 119  on extreme side regions, and a second shield  122 . When read head  100  is operated in a CPP fashion, shields  102  and  122  act as leads for read head  100  to allow current to flow through read element  104 . 
         [0019]    Read head  100  has a scratch exposure region  130  that is especially susceptible to scratches. A scratch exposure region refers to a region or area of a read head where a read element or a hard bias layers are formed between a bottom shield and a top shield. Scratch exposure region  130  is essentially the area between shields  102  and  122  where either hard bias layers  110 - 111  or read element  104  are formed. In other words, the scratch exposure region  130  is the width from one end of hard bias layer  110  to the other end of hard bias layer  111 . In this region, only thin insulating layers  106 - 107  separate first shield  102  and hard bias layers  110 - 111 . Because insulating layers  106 - 107  are very thin, it may be easy to scratch metallic material from first shield  102  across insulating layer  106  to contact hard bias layer  110 . With hard bias layer  110  being in contact with the second shield  122 , this scratch causes a short between the shields  102  and  122 . 
         [0020]      FIG. 2  illustrates read head  100  during fabrication. At this point in fabrication, read element  104  is formed on the first shield  102 , and hard bias layers  110 - 111  are formed on side regions of read element  104 . Those skilled in the art understand that read head fabrication such as this is typically performed at the wafer level, but an individual read head is shown just for example. 
         [0021]    Read head  100  as shown in  FIG. 2  may be fabricated according to different fabrication techniques. In one fabrication technique, the first shield  102  is formed and magnetoresistance (MR) layers are deposited on the first shield  102 . A first resist is then formed on the MR layers, and the MR layers are milled to remove the excess MR material and to define the stripe height of read element  104 . The first resist is then removed. To define the track width of read element  104 , a second resist is formed on the MR layers. A milling process is then performed to define the track width of read element  104 . Insulating layers  106 - 107  and hard bias layers  110 - 111  are then deposited, and the second resist is removed. These fabrication steps result in the structure shown in  FIG. 2 . Other fabrication processes may also be used to form the resultant structure shown in  FIG. 2 . 
         [0022]    After the track width of read element  104  and the hard bias layers  110 - 111  are defined, such as in  FIG. 2 , conventional fabrication processes deposit gap fill material  118 - 119 , and form the second shield  122 . Unfortunately, the scratch exposure region  130  may be larger than desired. The following description illustrates how to reduce the scratch exposure region. 
         [0023]      FIGS. 3-12  and the following description depict specific exemplary embodiments of the invention to teach those skilled in the art how to male and use the invention. For the purpose of teaching inventive principles, some conventional aspects of the invention have been simplified or omitted. Those skilled in the art will appreciate variations from these embodiments that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific embodiments described below, but only by the claims and their equivalents. 
         [0024]      FIG. 3  is a flow chart illustrating a method  300  of fabricating a read head with a reduced scratch exposure region in an exemplary embodiment of the invention. Method  300  is performed on a read head structure such as shown in  FIG. 2 , where the read head includes a first shield, a read element formed on the first shield, and hard bias layers formed on either side of the read element.  FIGS. 4-7  illustrate a read head  400  formed during fabrication according to method  300  in exemplary embodiments of the invention. The steps of method  300  may not be all-inclusive, and may include other steps not illustrated for the sake of brevity. 
         [0025]    Step  302  of  FIG. 3  comprises forming a mask structure to protect the read element and portions of the hard bias layers proximate to the read element.  FIG. 4  illustrates a read head  400  with a mask structure  440  formed according to step  302 . Read head  400  includes a first shield  402  and a read element  404  formed on the first shield  402 . Read head  400  also includes hard bias layers  410 - 411  that are formed on both sides of read element  404 . The hard bias layers  410 - 411  are separated from read element  404  and the first shield  402  by insulating layers  406 - 407 . Read head  400  also includes refill material  414 - 415 . 
         [0026]    According to step  302 , mask structure  440  is formed on read element  404  and portions  442 - 443  of hard bias layers  410 - 411  that are adjacent to read element  404 . Mask structure  440  thus protects read element  404  and the portions  442 - 443  of hard bias layer  410 - 411  that are adjacent to read element  404 . Mask structure  440  may comprise a photo-resist or any other type of mask or resist. Mask structure  440  may also be a bi-layer structure, such as is illustrated in  FIG. 4 . Mask structure  440  may be formed to define the practical minimum for the width of hard bias layers  410 - 411 . If the width of hard bias layers  410 - 411  is below this practical minimum, then they may not provide effective biasing for read element  404 . 
         [0027]    Step  304  comprises performing a removal process to remove other portions of the hard bias layers that are not protected by the mask structure.  FIG. 5  illustrates read head  400  after the removal process of step  304 . The removal process removes the material not protected by mask structure  440 , which is the remaining portion of hard bias layers  410 - 411  and some insulating material. The removal process may comprise a milling process or some other process. 
         [0028]    Step  306  comprises depositing insulating material. This is a full film deposition step where insulating material is deposited over the wafer.  FIG. 6  illustrates read head  400  with the insulating material  602  deposited as in step  306 . Insulating material  602  refills the regions of read head  400  where portions of hard bias layers  410 - 411  were removed during step  304 . Further, insulating material  602  may be formed to a thickness greater than hard bias layers  410 - 411 . For example, a thickness of insulating material  602  may be at least 50 nm. Thus, insulating material  602  is more difficult to scratch across than the removed portions of hard bias layers  410 - 411  which are electrically conductive. 
         [0029]    Step  308  comprises removing the mask structure.  FIG. 7  illustrates read head  400  with the mask structure removed as in step  308 . Read head  400  as fabricated according to method  300  advantageously has a reduced scratch exposure region  730  as compared to read head  100  shown in  FIGS. 1-2 . Scratch exposure region  730  is essentially the area between shield  402  and the future second shield (not shown) where either hard bias layers  410 - 411  or read element  404  are formed. Because hard bias layers  410 - 411  where “trimmed” in step  304 , the total area of the scratch exposure region is reduced. Much of the hard bias layers  410 - 411  were removed and replaced with insulating material  602 . Insulating material  602  is more difficult to scratch across, making read head  400  less susceptible to scratching. 
         [0030]      FIG. 8  is a flow chart illustrating a further method  800  of fabricating a read head with a reduced scratch exposure region in an exemplary embodiment of the invention. Method  800  is one possible extension of method  300 .  FIGS. 9-12  illustrate a read head  400  formed during fabrication according to method  800  in exemplary embodiments of the invention. The steps of method  800  may not be all-inclusive, and may include other steps not illustrated for the sake of brevity. 
         [0031]    Step  802  comprises forming another mask structure to protect the read element, the first portions of the hard bias layers, and portions of the insulating material proximate to the hard bias layers.  FIG. 9  illustrates read head  400  with mask structure  902  formed according to step  802 . Mask structure  902  protects read element  404 , the remaining hard bias layers  410 - 411 , and portions of insulating material  602  that is proximate to hard bias layers  410 - 411 . 
         [0032]    Step  804  comprises depositing gap fill material. This is a full film deposition step where gap fill material, such as alumina, is deposited over the wafer.  FIG. 10  illustrates read head  400  with gap fill material  1002  deposited according to step  804 . 
         [0033]    Step  806  comprises removing the mask structure.  FIG. 11  illustrates read head  400  with mask structure  902  removed according to step  806 . Step  808  comprises forming a second shield for the read head.  FIG. 12  illustrates read head  400  with a second shield  1202  formed according to step  808 . 
         [0034]    The structure of read head  400  as illustrated in  FIG. 12  has advantages as compared to a conventional read head as shown in  FIG. 1 . First, the scratch exposure region  730  of read head  400  is reduced as compared to the scratch exposure region  130  of conventional read head  100 . The scratch exposure region  730  of read head  400  is reduced because some of the hard bias layers  410 - 411  are trimmed leaving only portions that are proximate to the read element  404 . The areas formerly populated with the hard bias layers are filled with insulating material and/or gap fill material. Thus, there is less electrically conductive material between the first shield  402  and the second shield  1202  that can be smeared such as to create a short between the shields. The result is that read sensor  400  has less of a probability of experiencing significant performance degradation due to shorting of the first shield  402  to the second shield  1202 . 
         [0035]    Although specific embodiments were described herein, the scope of the invention is not limited to those specific embodiments. The scope of the invention is defined by the following claims and any equivalents thereof.