Abstract:
A wrap around shield of a write head is fabricated in multiple processes, with side shields fabricated in one process, and a trailing shield formed in another process. These multiple processes form a stitched wrap around shield, resulting in more flexible and accurate placement of the trailing shield and side shields with respect to the write pole. These processes also independently form the dimensions (shapes and sizes) of the side shields and the trailing shield which allows better control of writeability, saturation, and adjacent track interference of the perpendicular recording write head.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention is related to the field of perpendicular magnetic recording (PMR) on magnetic recording hard disk drive systems and, in particular, to fabricating a stitched wrap around shield for a PMR write head. 
         [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 utilizing perpendicular recording, data is recorded on a magnetic recording disk by magnetizing the recording medium in a direction perpendicular to the surface of the disk. In this type of recording, the magnetic easy axes of the magnetic grains which store the recorded data are arranged perpendicular to the disk surface, instead of parallel to the disk surface as is the case in longitudinal recording. Perpendicularly recorded data is more stable than longitudinal data, and the data can be recorded at a higher density than longitudinal data. The coercivity of the medium is higher, since the magnetic recording layer is in effect “inside the gap” between the head and a soft underlayer (SUL) that is located under the magnetic layer. In addition, for the same read head design, perpendicular data provides greater read back amplitude. The disk has a higher magnetic moment-thickness product (MrT). For the same physical width of the read head, the magnetic read width is narrower. 
         [0006]    High track density heads use narrow write pole widths. A sufficiently short flare length (i.e., the distance between the ABS and the point where the write pole flares out) is used to maintain the write field strength of a narrow track width perpendicular write head. As a result, the widened portion of a write pole behind the flare point is close to the recording medium and can produce undesired fields to the extent that the data in adjacent tracks may be erased. A balance between writeability and adjacent track interference (ATI) is needed for high track density perpendicular write heads. 
         [0007]    Wrap around shield designs are utilized for high track density recording to shield adjacent tracks from unintended recording.  FIG. 1  illustrates an ABS view of a typical write head  100  with a wrap around shield  120 . As shown in  FIG. 1 , wrap around shield  120  has a trailing shield  122  placed in the proximity of the trailing surface  112  of the write pole  110 , separated from write pole  110  by a gap  135 . The function of trailing shield  122  is to improve the write field gradient and transition curvature of write pole  110 . Wrap around shield  120  also has side shields  124  and  126  disposed on sides of write pole  110 . Side shields  124  and  126  are separated from write pole  110  by a gap  130 . Utilizing wrap around shield  120 , the fringe fields are mostly confined between write pole  110  and side shields  124  and  126  and therefore the fringe fields create much less interference with adjacent tracks. Gap  135  is smaller than gap  130 , and the thickness for both is important for proper write performance, and thus, there is a need for accurately controlling the thickness of trailing gap  135  and side gap  130  during manufacturing. 
         [0008]    In prior art processes, trailing shield  122  and side shields  124  and  126  are fabricated at the same time. As a result, the manufacturing process focuses more on the alignment of trailing shield  122  with write pole  110  than the alignment of side shields  124  and  126  with write pole  110 . This is because the tolerance of aligning trailing shield  122  with write pole  110  is less than the tolerance of aligning side shields  124  and  126  with write pole  110 . Further, prior art processes lack flexibility and require very aggressive design points, such as flare point and shield throat height, which are challenging for processing control during manufacture. Further, fabrication is more difficult because of the topography caused by present fabrication methods. 
       SUMMARY OF THE SOLUTION 
       [0009]    Embodiments of the invention solve the above and other related problems with improved methods for fabricating write heads. More specifically, a wrap around shield of a write head is fabricated in multiple processes, with side shields fabricated in one process, and a trailing shield formed in another process. These multiple processes form a stitched wrap around shield, with the side shields and trailing shield magnetically coupled. Advantageously, the gap between the side shields and the write pole may be accurately defined in one process, and the gap between the trailing shield and the write pole may be accurately defined in a separate process. As a result, the wrap around shield is more accurately aligned with the write pole. 
         [0010]    Further, the shapes and sizes of the trailing shield and side shields can be independently made and controlled to balance writeability, saturation, and adjacent track interference (ATI) of the write head. The trailing shield and the corresponding gap may be accurately defined on a more relatively flat surface. The placement of the side shields is easier and more accurately controlled compared to prior art wrap around shield fabrication processes, which focus more on the placement of the trailing shield. 
         [0011]    Further, a notch may be formed in the trailing shield gap and the trailing shield. A perpendicular head with a notched wrap around shield structure has less transition curvature and better writeability. The reduced transition curvature is due to the modification of the main pole field contour by the notched top write gap. The better writeability of the recording head is a result of less flux shunting to the shield. 
         [0012]    An embodiment of the invention is a method for forming a stitched wrap around shield of a write head. The method comprises forming a write pole of the write head. The method further comprises forming side shield gap structures on side regions of the write pole. The side shield gap structures may be formed by depositing a first layer of non-magnetic material. The method further comprises forming side shields on side regions of the write pole above the side shield gap structures. The side shield gap structures define a first gap separating the write pole and the side shields. The method further comprises removing portions of the first layer of non-magnetic material above the write pole. The method further comprises forming a trailing shield gap structure above the write pole, and forming a trailing shield of the write head. The trailing shield gap structure defines a second gap separating the write pole and the trailing shield, and the second gap is less than the first gap. Advantageously, the method allows the side shields and trailing shield to be formed separately, resulting in more accurate alignment of the shields with respect to the write pole, and independent sizes and shapes of the side shields and trailing shield. 
         [0013]    The invention may include other exemplary embodiments described below. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0014]    The same reference number represents the same element or same type of element on all drawings. 
           [0015]      FIG. 1  illustrates an ABS view of a write head with a wrap around shield. 
           [0016]      FIG. 2  illustrates a flow chart of a prior art method for fabricating the write head of  FIG. 1 . 
           [0017]      FIGS. 3-11  illustrate cross sectional views of a prior art write head of  FIG. 1  during fabrication according to the method of  FIG. 2 . 
           [0018]      FIG. 12  illustrates a method for fabricating a write head with a stitched wrap around shield in an exemplary embodiment of the invention. 
           [0019]      FIGS. 13-18  illustrate cross sectional views of a write head fabricated according to the method of  FIG. 12  in an exemplary embodiment of the invention. 
           [0020]      FIG. 19  illustrates a method for fabricating a write head with a stitched wrap around shield in another exemplary embodiment of the invention. 
           [0021]      FIGS. 20-29  illustrate cross sectional views of a write head fabricated according to the method of  FIG. 19  in an exemplary embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]      FIG. 2  illustrates a flow chart of a prior art method  200  for fabricating the write head  100  of  FIG. 1 .  FIGS. 3-11  illustrate cross sectional views of a prior art write head  100  during fabrication according to method  200  of  FIG. 2 . The steps of method  200  will be described in reference to write head  100  illustrated in  FIGS. 3-11 . 
         [0023]    In step  202 , laminated layers  304  of a write pole (e.g., write pole  110  of  FIG. 1 ) are deposited on an insulator layer  302  (see  FIG. 3 ). A hard masking layer  306  (such as Alumina) is deposited above laminated layers  304 . In step  204 , a photoresist mask structure  308  is formed (see  FIG. 4 ) using a photolithographic process. In step  206 , a reactive ion etching (RIE), ion milling, or reactive ion milling process is then performed to remove exposed portions of masking layer  306  not protected by photo resistive layer  308  to form hard mask structure  306  (see  FIG. 5 ). In step  208 , an ion milling process is performed to define write pole  110  (see  FIG. 6 ). In step  210 , a stripping process removes photoresist layer  308  (see  FIG. 7 ). 
         [0024]    In step  212 , a gap thickness of a wrap around shield  120  (see  FIG. 1 ) is defined around write pole  110 . First, a layer of non-magnetic material  802  (such as atomic layer deposition (ALD) Alumina) is deposited (see  FIG. 8 ). Ion milling removes non-magnetic material  802  above hard mask  306  (see  FIG. 9 ). Gaps are defined around write pole  110 , with the side shield gap  130  (see  FIG. 1 ) being the thickness of the layers of ALD Alumina  802 , and the trailing shield gap  135  (see  FIG. 1 ) being the thickness of the layer of Alumina mask  306 . In step  214 , an electroplating process is performed to fabricate wrap around shield  120  (see  FIG. 10 ). CMP is performed to planarize a top surface of write head  100 . 
         [0025]      FIG. 11  illustrates a top view of write head  100  after completion of step  212 . Trailing shield  122  is disposed on a trailing edge of write pole  110 . Below trailing shield  122  are side shields  124  and  126  on each side of write pole  110 . Side shields  124  and  126  drape from trailing shield  122 , and the dimensions of side shields  124  and  126  are determined by the dimensions of trailing shield  122 . Thus, write head  100  fabricated according to method  200  does not provide flexible control of independent sizes and shapes of trailing shield  122  and side shields  124  and  126 . As previously discussed, method  200  may not be adequately flexible to form gaps and shields of write head  100  to achieve desired writing performances. The processing control is also challenging during manufacture. The subsequently described methods of fabricating a stitched wrap around shield solves the previously described problems and other problems encountered in fabrication of write head  100 . 
         [0026]      FIGS. 12-29  and the following description depict specific exemplary embodiments of the invention to teach those skilled in the art how to make 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. 
         [0027]      FIG. 12  illustrates a method  1200  for fabricating a write head with a stitched wrap around shield in an exemplary embodiment of the invention.  FIGS. 13-18  illustrate cross sectional views of a write head  1300  fabricated according to method  1200  of  FIG. 12  in an exemplary embodiment of the invention. The steps of method  1200  will be described in reference to write head  1300  illustrated in  FIGS. 13-18 . The steps of method  1200  may not be all-inclusive, and may include other steps not shown for the sake of brevity. 
         [0028]    Step  1202  comprises forming a write pole  1304  (see  FIG. 13 ) above insulator layer  1302  using hard mask  1306  (e.g., Alumina material) of write head  1300 . Step  1204  comprises forming side shield gap structure  1402  (see  FIG. 14 ) of write head  1300 . Side shield gap structure  1402  may be formed by depositing one or more layers of non-magnetic material (such as ALD Alumina). The deposition thickness of the layers of non-magnetic material may correspond to the desired side shield gap thickness of write head  1300 . The resulting structure of write head  1300  is illustrated in  FIG. 14 . 
         [0029]    Step  1206  comprises ion milling to remove a top portion of the non-magnetic material (e.g. side shield gap structure  1402 ) to form a trailing shield gap  1306 , and to remove a bottom portion of the non-magnetic material to allow subsequently formed side shields to cover write pole  1304  (see  FIG. 15 ). 
         [0030]    Step  1208  comprises forming side shields  1602  (see  FIG. 16 ) of write head  1300 . Side shields  1602  may be formed through an electroplating process, and a CMP process may be used to planarize side shields  1602  to mask structure  1306 . The resulting structure of write head  1300  is illustrated in  FIG. 16 . 
         [0031]    Step  1210  comprises forming a trailing shield  1702  (see  FIG. 17 ). Trailing shield  1702  may be formed through an electroplating process. A CMP process may be used to planarize trailing shield  1702  to a desired height. The resulting structure of write head  1300  is illustrated in  FIG. 17 . 
         [0032]      FIG. 18  illustrates a top view of write head  1300  after completion of step  1210 . Trailing shield  1702  is disposed on a trailing edge of write pole  1304 . Below trailing shield  1702  is a side shield  1602  on each side of write pole  1304 . Side shields  1602  don&#39;t drape from trailing shield  1702  like the side shields of write head  100  in  FIG. 11 . Advantageously, write head  1300  of  FIGS. 17-18  has a side shield gap defined by side shield gap structure  1602  and a trailing shield gap defined by mask structure  1306 . These gaps are of different widths and more accurately aligned with write pole  1304 . Also, the dimensions of side shields  1602  are determined independently of the dimensions of trailing shield  1702  and are more flexibly controlled, as are the dimensions of trailing shield  1702 . 
         [0033]      FIG. 19  illustrates a method  1900  for fabricating a write head with a stitched wrap around shield in another exemplary embodiment of the invention.  FIGS. 20-29  illustrate cross sectional views of a write head  2000  fabricated according to method  1900  of  FIG. 19  in an exemplary embodiment of the invention. The steps of method  1900  will be described in reference to write head  2000  illustrated in  FIGS. 20-29 . The steps of method  1900  may not be all-inclusive, and may include other steps not shown for the sake of brevity. 
         [0034]    Step  1902  comprises forming a write pole  2004  (see  FIG. 20 ) of write head  2000 . Write pole  2004  may be formed over an insulator layer  2002  in a similar manner as described in steps  202  to  208  of method  200  of  FIG. 2 . The laminated layers may be AFC CoFe/Cr/CoFe/CrNi. The stripping process may be performed in multiple steps, such as a Tetra-methyl ammonium hydroxide (TMAH) etching process, an N-methyl pyrrolidinone (NMP) stripping process, and an O 2  RIE process to remove the photoresist mask. As such, a hard mask Alumina structure  2006  may be present above write pole  2004  after the write pole definition process is completed. The resulting structure of write head  2000  is illustrated  FIG. 20 . 
         [0035]    Step  1904  comprises depositing one or more layers of non-magnetic material to define a side gap of write pole  2004 . First, a layer of non-magnetic material  2102  (see  FIG. 21 ) may be deposited, such as ALD Alumina. 
         [0036]    In step  1906 , an Ar ion milling process is performed to remove non-magnetic material  2102  above hard mask layer  2006  on top of write pole  2004 . The ion milling process may be performed at an angle between 45-60 degrees using SIMS end point detection, such as an angle of 55 degrees. The ion milling process end point may be controlled by detecting Ta, Ti, and Si if hard mask structure  2006  comprises a TaO 2  layer, a TiO 2  layer, or a SiO 2  layer above a hard mask Alumina layer. The ion mill process also removes the bottom regions of non-magnetic material  2102  on each side of write pole  2004  to allow subsequently formed side shields to cover write pole  2004 . The resulting structure of write head  2000  is illustrated in  FIG. 22 . 
         [0037]    In step  1908 , a layer of non-magnetic material  2302  (see  FIG. 23 ) may be deposited, such as an Rh layer, which acts as a seed layer for electroplating the side shields as well as a stop layer during a subsequent CMP process. Multiple layers may form non-magnetic material  2102 , such as 5 nm of Ta, 15 nm of Rh and 5 nm of CoFe. The Ta acts as an adhesion layer, the Rh acts as an electroplating seed and a CMP stop layer, and the CoFe acts as a photo adhesion promotion layer for an electroplating process. The resulting structure of write head  2000  is illustrated in  FIG. 23 . 
         [0038]    Step  1910  comprises depositing side shield material  2402  (see  FIG. 24 ). Side shield material  2402  may be deposited using an electroplating process with non-magnetic layer  2302  (e.g., an electroplating seed layer). CMP is performed on side shield material  2402  down to non-magnetic layer  2302  (e.g., the CMP stop layer) to planarize side shield material  2402  and form side shields  2402 . Non-magnetic material  2302  may act as both an electroplating seed layer and a CMP stop layer for the CMP process. For electroplating seed layer purposes, non-magnetic material  2302  may be Rh, Ru, or Au. For CMP stop layer purposes, Rh provides better properties than Ru, and Ru provides better properties than Au. Side shields  2402  are separated from write pole  2004  by a side gap defined by non-magnetic material  2102  and non-magnetic material  2302 . The side gap may be between about 20 nm and about 200 nm. The resulting structure of write head  2000  is illustrated in  FIG. 24 . 
         [0039]    Step  1912  comprises ion milling to remove non-magnetic material  2302  above hard mask layer  2006  on write pole  2004 . An Ar ion milling process controlled by SIMS end-point detection of mask structure  2006  may be used to remove non-magnetic material  2302  above hard mask layer  2006 . For example, the ion milling process may detect Ta, Ti, and Si if hard mask structure  2006  comprises a TaO 2  layer, a TiO 2  layer, or a SiO 2  layer on a hard mask Alumina layer. An RIE process may be performed, if necessary, to remove the TaO 2  layer, the TiO 2  layer, or the SiO 2  layer on a hard mask Alumina layer  2006 . The ion milling process may also form a notch in write head  2000  after removing non-magnetic material  2302  above hard mask Alumina layer  2006 . The resulting structure of write head  2000  is illustrated in  FIG. 25 . 
         [0040]    Step  1914  comprises depositing a layer of non-magnetic material  2602  (see  FIG. 26 ), which acts as an electroplating seed layer. Step  1916  comprises milling to remove portions of non-magnetic material  2602  from each side region of write pole  2004  using a patterned photo mask to fabricate contacts in non-magnetic material  2602  on each side of write pole  2004 . The contacts allow contact between side shields  2402  and a trailing shield. The resulting structure of write head  2000  is illustrated in  FIG. 27 . 
         [0041]    Step  1918  comprises forming a trailing shield  2802  (see  FIG. 28 ) above non-magnetic material  2602  (i.e., above a trailing surface of write pole  2004 ). Trailing shield  2802  may be formed by depositing trailing shield material using an electroplating process, and performing CMP to planarize the trailing shield material to a desired height to form trailing shield  2802 . Trailing shield  2802  is separated from write pole  2004  by a second gap defined by a thickness non-magnetic material  2602  and a thickness of hard mask Alumina layer  2006 . The trailing gap may be between about 10 nm and about 50 nm. The resulting structure of write head  2000  is illustrated in  FIG. 28 . The notch which may be formed in trailing shield gap structure  2602  (see above write pole  2004  in  FIG. 28 ) achieves better transition curvature and less flux shunting to the stitched wrap around shield for better writeability of write head  2000 . 
         [0042]      FIG. 29  illustrates a top view of write head  2000  after completion of step  1914 . Trailing shield  2802  is disposed on a trailing edge of write pole  2004 . Below trailing shield  2802  is a side shield  2402  on each side of write pole  2004 . Side shields  2402  don&#39;t drape from trailing shield  2802  like the side shields of write head  100  in  FIG. 11 . Thus, the dimensions of side shields  2402  advantageously are determined independently of the dimensions of trailing shield  2802  and are more flexibly controlled, as are the dimensions of trailing shield  2802 . 
         [0043]    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.