Abstract:
Methods and structures for the fabrication of a thin film, perpendicular recording write head are disclosed. The fabrication involves the deposition of two different oxide layers which have mutually high etch selectivities. This characteristic allows a write pole structure to be built wherein the track width is independent of the location of the flare point. The process also produces a structure wherein the throat height of the shield is self aligned to the location of the flare point of the write pole.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to structures and methods for fabricating thin film magnetic write heads. More specifically, the invention relates to structures and methods for fabricating a thin film write head for perpendicular recording having independent control of track width, flare point, and a wrap around shield throat height which is self aligned to the flare point of the write pole. The methods and structure also provide for stepped wrap around shields wherein the thickness or depth (from the ABS) of the wrap around shield increases in the region above the write pole. 
         [0003]    2. Description of the Related Art 
         [0004]    As areal densities for magnetic storage hard disk drives continue to increase, the critical dimensions for thin film write heads are driven to smaller levels. For future designs, track widths (TW), flare points (FP), and wrap around shield throat heights (TH) will be on the order of 60 nm. Holding these dimensions provides a significant challenge for conventional processing, as will be illustrated in  FIG. 1 .  FIG. 1  (Prior Art) is a partial plan view  100  of a typical thin film perpendicular write pole  212 . Write pole  212  is typically imbedded in oxide layer  112 , and is deposited after imaging the shape of the pole and etching oxide layer  112 . Alternatively, write pole layer  212  can be blanket deposited, then imaged to define the final shape, etched or ion milled to define the pole, with areas around the pole subsequently filled with an oxide layer and both layers planarized. In either case, current imaging and etching processes can create errors with respect to the location of the flare point  102 , since the position where the flare point is located by lithography FP d  ref  104  will not be the actual location of the flare point FP a  ref  106  subsequent to etching/milling of the pole material  212 , or oxide layer within which the pole material is deposited. Errors can also be introduced with respect to the track width TW. The imaged track width TW d  ref  108  may be larger or smaller than the actual value TW a  ref  110 . These errors also impact the location of the flare point. As dimensions are reduced, the location errors of the flare point can significantly impact the performance of the write head. Similar errors are introduced when locating and etching the cavities for the wrap around shield. The throat height, or the depth or thickness of the wrap around shield from the ABS, is critical to the performance of the write head. More particularly, the location of the rear of the wrap around shield relative to the flare point is critical, and is subject to significant errors when conventional lithography and etching processes are utilized to fabricate the shield. What is needed is a better process for producing perpendicular thin film write heads. 
         [0005]      FIG. 2  (Prior Art) is a partial, cross sectional view of a typical thin film perpendicular write head  200 . The head comprises shield layers  202 ,  204 , shaping layer  210 , coil structure  208 , main pole  212 , lower return pole layer  206 , wrap around shield  214 , and upper return pole layer  216 . Alternatively, structure  214  may also be a trailing shield. Main pole  212  is typically deposited over spacer layer  112 . Details of wrap around shields and trailing shields, as applied to perpendicular recording heads, can be found in, for example, US Patent Application Publications 2007/0146930, 2007/0115584, 2006/0174474, 2006/0044682, and 2007/0137027. 
       SUMMARY OF THE INVENTION 
       [0006]    It is an object of the present invention to provide a thin film perpendicular magnetic head containing a write pole having a first flare point and a second flare point, the write pole having a first portion extending from an air bearing surface to the first flare point, the first portion having a constant first width, the write pole having a second portion extending from the first flare point to the second flare point, the second portion having a constant second width greater than the first width. 
         [0007]    It is another object of the present invention to provide a method for making a thin film perpendicular magnetic head including depositing a first oxide layer and a second oxide layer on a surface, such that the first oxide layer and the second oxide layer share an interface boundary approximately perpendicular to the surface; depositing a mask layer over a first portion of the first oxide layer and over a first portion of the second oxide layer; creating an opening of in the mask layer, the opening exposing a second portion of the first oxide layer and a second portion of the second oxide layer, the opening extending across the interface boundary; isotropically etching, with a first process, the second portion of the second oxide layer to form a first trench; anisotropically etching, with a second process, the second portion of the first oxide layer, subsequent to isotropically etching the second oxide layer with the first process, to form a second trench, wherein the second portion of the first oxide layer is exposed to conditions of the first process, and the width of the first trench is greater than the width of the second trench; and, depositing a magnetic material in the first and second trenches to form at least a portion of a write pole. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The present invention will be better understood when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings, wherein: 
           [0009]      FIG. 1  (Prior Art) is a partial plan view of a typical thin film perpendicular write pole; 
           [0010]      FIG. 2  (Prior Art) is a partial cross section view of a typical thin film perpendicular write head structure; 
           [0011]      FIG. 3   a  is a partial plan view of a substrate subsequent to the deposition of a blanket etch stop layer in accordance with embodiments of the present invention; 
           [0012]      FIG. 3   b  is a cross section view through section A-A of  FIG. 3   a  in accordance with embodiments of the present invention; 
           [0013]      FIG. 4  is a cross section view of  FIG. 3   b  subsequent to the deposition of a blanket layer of oxide  1  in accordance with embodiments of the present invention; 
           [0014]      FIG. 5   a  is a plan view of  FIG. 4  subsequent to the etching of oxide  1  in accordance with embodiments of the present invention; 
           [0015]      FIG. 5   b  is cross section view through section B-B of  FIG. 5   a  in accordance with embodiments of the present invention; 
           [0016]      FIG. 6  is a cross section view of  FIG. 5   b  subsequent to the blanket deposition of oxide  2  in accordance with embodiments of the present invention; 
           [0017]      FIG. 7   a  is a plan view of  FIG. 6  subsequent to the planarization of oxide  2  in accordance with embodiments of the present invention; 
           [0018]      FIG. 7   b  is a cross section view through section C-C of  FIG. 7   a  in accordance with embodiments of the present invention; 
           [0019]      FIG. 8  is a cross section view of  FIG. 7   b  subsequent to the blanket deposition of an etch mask layer in accordance with embodiments of the present invention; 
           [0020]      FIG. 9   a  is a cross section view of  FIG. 8  subsequent to the blanket deposition of a photo resist layer in accordance with embodiments of the present invention; 
           [0021]      FIG. 9   b  is a plan view of  FIG. 9   a  subsequent to the patterning of mask layer  802  in accordance with embodiments of the present invention; 
           [0022]      FIG. 10  is a plan view of  FIG. 9   b  subsequent to the selective etching of oxide  2  in accordance with embodiments of the present invention; 
           [0023]      FIG. 11  is a cross section view through section D-D of  FIG. 10  in accordance with embodiments of the present invention; 
           [0024]      FIG. 12  is a cross section view through section E-E of  FIG. 10  in accordance with embodiments of the present invention; 
           [0025]      FIG. 13  is a cross section view of  FIG. 12  subsequent to the etching of oxide  1  in accordance with embodiments of the present invention; 
           [0026]      FIG. 14   a  is a plan view of  FIG. 13  subsequent to removal of mask layer  802  in accordance with embodiments of the present invention; 
           [0027]      FIG. 14   b  is a cross section view through section G-G of  FIG. 14   a  in accordance with embodiments of the present invention; 
           [0028]      FIG. 15  is a cross section view of  FIG. 14   b  subsequent to the blanket deposition of a plating seed layer in accordance with embodiments of the present invention; 
           [0029]      FIG. 16  is a cross section view of  FIG. 15  subsequent to electroplating of magnetic pole material in accordance with embodiments of the present invention; 
           [0030]      FIG. 17  is a cross section view of  FIG. 16  subsequent to the planarization of the pole material in accordance with embodiments of the present invention; 
           [0031]      FIG. 18  is a plan view of  FIG. 17  subsequent to the removal of oxide  1  in accordance with a first embodiment of the present invention; 
           [0032]      FIG. 19  is a cross section view through section H-H of  FIG. 18  in accordance with a first embodiment of the present invention; 
           [0033]      FIG. 20  is a cross section view of  FIG. 19  subsequent to the blanket deposition of gap layer  2002  in accordance with a first embodiment of the present invention; 
           [0034]      FIG. 21   a  is a plan view of  FIG. 20  subsequent to the deposition, imaging and development of photo resist layer  2102  in accordance with a first embodiment of the present invention; 
           [0035]      FIG. 21   b  is a cross section view through section H-H of  FIG. 21   a  in accordance with a first embodiment of the present invention; 
           [0036]      FIG. 21   c  is a cross section view through section J-J of  FIG. 21   a  in accordance with a first embodiment of the present invention; 
           [0037]      FIG. 22   a,b  are cross section views of  FIG. 21   b,c , respectively, subsequent to shield deposition in accordance with a first embodiment of the present invention; 
           [0038]      FIGS. 23   a,b  are cross section views of  FIGS. 22   a,b , respectively, subsequent to lapping in accordance with a first embodiment of the present invention; 
           [0039]      FIG. 24  is a cross section view of  FIG. 17  subsequent to blanket deposition of a second oxide 1 layer  2402 , mask layer  2404  and photo resist layer  2406  in accordance with a second embodiment of the present invention; 
           [0040]      FIG. 25   a  is a plan view of  FIG. 24  subsequent to the patterning of mask layer  2404  and removal of oxide  1  in accordance with a second embodiment of the present invention; 
           [0041]      FIG. 25   b  is a cross section view through section K-K of  FIG. 25   a  in accordance with a second embodiment of the present invention; 
           [0042]      FIG. 25   c  is a cross section view through section L-L of  FIG. 25   a  in accordance with a second embodiment of the present invention; 
           [0043]      FIGS. 26   a,b  are cross section views of  FIG. 25   b,c , respectively, subsequent to the removal of mask layer  2404  and deposition of gap layer  2602  in accordance with a second embodiment of the present invention; 
           [0044]      FIGS. 27   a,b  are cross section views of  FIG. 26   a,b , respectively, subsequent to the deposition, imaging, and development of photo resist layer  2704  in accordance with a second embodiment of the present invention; 
           [0045]      FIGS. 28   a,b  are cross section views of  FIGS. 27   a,b , respectively, subsequent to the deposition of shield layer  2802  and deposition of filler oxide  2804  in accordance with a second embodiment of the present invention; 
           [0046]      FIG. 29   a,b  are cross section views of  FIGS. 28   a,b , respectively, subsequent to lapping in accordance with a second embodiment of the present invention; 
           [0047]      FIG. 30  is a plan view of the finished structure of  FIGS. 29   a,b  and  23   a,b  in accordance with embodiments of the present invention; 
           [0048]      FIG. 31  is a cross section view through section M-M of  FIG. 30  in accordance with embodiments of the present invention; and, 
           [0049]      FIG. 32  is a plan view through section N—N of  FIG. 31  in accordance with embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0050]      FIGS. 1 and 2  (Prior Art) have been discussed above in the Background section. With respect to subsequent figures, a first embodiment of the present invention is disclosed in  FIGS. 3-23   a,b . A second embodiment of the present invention is disclosed in  FIGS. 3-17 , and  24 - 29   a,b .  FIGS. 30-32  apply to both first and second embodiments, as do  FIGS. 3-17 . Details of the embodiments are best described via a sequential process of construction. 
         [0051]      FIG. 3   a  is a partial plan view  300  of a substrate subsequent to the deposition of a blanket etch stop layer  302  in accordance with embodiments of the present invention.  FIG. 3   b  is a cross section view  301  through section A-A of  FIG. 3   a . Support layer  304  is typically a spacer layer comprising a dielectric material similar to layer  112  of  FIG. 2  (Prior Art). 
         [0052]      FIG. 4  is a cross section view  400  of  FIG. 3   b  subsequent to the deposition of a blanket layer  402  of oxide  1  in accordance with embodiments of the present invention. A photo resist layer is then deposited over oxide 1 layer  402  (not shown), imaged, and developed in accordance with processes well known to those skilled in the art. Portions of oxide 1 layer  402  are then etched to stop layer  302 , the resultant structure is shown in  FIGS. 5   a,b.    
         [0053]      FIG. 5   a  is a plan view  500  of  FIG. 4  subsequent to the etching of oxide 1 layer  402  in accordance with embodiments of the present invention.  FIG. 5   b  is cross section view through section B-B of  FIG. 5   a . The remaining “island” of oxide 1 layer  402  takes the shape of the wrap around shield, having a preliminary location of the Air Bearing Surface (ABS) shown as ABS (ref). This is a provisional location, as the actual ABS location will be finalized by a lapping process. Dimension  502  represents a preliminary throat height, or the thickness of the subsequently constructed shield structure (at the write pole), as measured from the ABS. In the next step, a blanket layer of second oxide, denoted oxide  2 , is deposited over the structure shown in  FIG. 5   b.    
         [0054]      FIG. 6  is a cross section view  600  of  FIG. 5   b  subsequent to the blanket deposition of oxide 2 layer  602  in accordance with embodiments of the present invention. Oxide  1  and oxide  2  are chosen to have unique selectivities when undergoing a reactive ion etch (RIE) processing. That is, when oxide  1  is being etched, oxide  2  is minimally affected. Likewise, when oxide  2  is being etched, oxide  1  is minimally affected. Some examples of oxide  1 /oxide  2  pairs include, but are not limited to: 
         [0055]    I. Oxide  1 : SiO 2 ; Oxide  2 : Si 3 N 4    
         [0056]    II. Oxide  1 : SiO 2 ; Oxide  2 : Al 2 O 3    
         [0000]    For pair I, SiO2 etching is performed with carbon rich fluorocarbon gases such as C 3 F 8  and C 4 F 8 . Si 3 N 4  etching is performed with mixtures of CF 4 /O 2 /N 2 , or SF 6 /CH 4 /N 2 /O 2 . When etching SiO 2  in the presence of Si 3 N 4 , selectivities range from 4:1 up to 30:1. When etching Si 3 N 4  in the presence of SiO 2 , selectivity is about 6:1. For pair II, SiO 2  etching is performed with mixtures of CHF 3 /CF 4  with a SiO 2 /Al 2 O 3  selectivity of about 10:1. Al 2 O 3  etching is performed in BCl 3  with a Al 2 O 3 /SiO 2  selectivity of about 10:1. Etch stop layer  302  is preferably a metal layer, comprising Ru, Rh, or Cr. 
         [0057]    In an alternate embodiment of the present invention, pair I can be Oxide  1 : SiO 2 ; Oxide  2 : Si 3 N 4 . Pair  2  can be Oxide  1 : SiO 2 ; Oxide  2 : Al 2 O 3 . The foregoing limitations on the etch chemistries and selectivities apply. 
         [0058]    After oxide 2 layer  602  is deposited, the structure is planarized, the steps of which are well known to those skilled in the art. This is done to remove the portions of oxide 2 layer  602  covering oxide 1 layer  402 . For planarization by CMP, some of these steps (not shown) include the deposition of a CMP stop layer, planarization, and removal of the stop layer by ion milling or RIE. 
         [0059]      FIG. 7   a  is a plan view  700  of  FIG. 6  subsequent to the planarization of oxide 2 layer  602  in accordance with embodiments of the present invention.  FIG. 7   b  is a cross section view  701  through section C-C of  FIG. 7   a . Following planarization, a blanket etch mask layer is deposited on the planarized surface. 
         [0060]      FIG. 8  is a cross section view  800  of  FIG. 7   b  subsequent to the blanket deposition of an etch mask layer  802  in accordance with embodiments of the present invention. Layer  802  is preferably a metal, resistant to the etch conditions used to etch oxide 2 layer  602 . Layer  802  may be chosen from (but is not limited to) Ru, Rh, and Cr. A photo resist layer is then deposited on layer  802  in order to pattern the layer. 
         [0061]      FIG. 9   a  is a cross section view  900  of  FIG. 8  subsequent to the blanket deposition of a photo resist layer  902  in accordance with embodiments of the present invention.  FIG. 9   b  is a plan view  901  of  FIG. 9   a  subsequent to the patterning of mask layer  802  in accordance with embodiments of the present invention. Mask layer  802  is patterned to expose the underlying oxide layers  602  and  402  in the shape of write pole (main pole). Following this step, oxide 2 layer  602  will be selectively etched. 
         [0062]      FIG. 10  is a plan view  1000  of  FIG. 9   b  subsequent to the selective etching of oxide 2 layer  602  in accordance with embodiments of the present invention. In the regions where oxide 2 layer  602  was etched, etch stop layer  302  is exposed. Due to the selective nature of the RIE process to etch oxide 2 layer  602 , the exposed portion of oxide layer  402  is minimally etched. 
         [0063]      FIG. 11  is a cross section view  1100  through section D-D of  FIG. 10  in accordance with embodiments of the present invention. Etch conditions are chosen to create undercutting of oxide 2 layer  602  in the vicinity of open portions of mask layer  802 . This creates an actual etched trench width of nominally TW′ (ref  1102 )+2 D (ref  1104 ). Typically, distance D is about 50% of mask opening TW′, but can be as large as 100% of TW′.  FIG. 12  is a cross section view  1200  through section E-E of  FIG. 10 . Since this a cross section through oxide 1 layer  402 , no etching occurs even though mask layer  802  has an opening of TW′ (ref  1102 ). 
         [0064]      FIG. 13  is a cross section view  1300  of  FIG. 12  subsequent to the etching of oxide 1 layer  402  in accordance with embodiments of the present invention. Etch conditions are chosen to minimize any undercutting of oxide 1 layer  402 .  FIG. 14   a  is a plan view  1400  of  FIG. 13  subsequent to removal of mask layer  802 .  FIG. 14   b  is a cross section view  1401  through section G-G of  FIG. 14   a . Plan view  1400  shows two different trench widths in the “neck” portion of the funnel. In the region bordered by oxide 1 layer  402 , the trench has a nominal width of TW′. In the regions bordered by oxide 2 layer  602 , the width of the trench is TW′+2 D. This creates a notch  1106  at the interface between oxide  1  and oxide  2 . The location of this notch is determined by the original location of the oxide  1  “island” as shown in  FIG. 5   a , and is the result of the undercut while etching oxide 2 layer  602 , relative to the etching characteristics of oxide 1 layer  402 . 
         [0065]      FIG. 15  is a cross section view  1500  of  FIG. 14   b  subsequent to the blanket deposition of a plating seed layer  1502  in accordance with embodiments of the present invention.  FIG. 16  is a cross section view  1600  of  FIG. 15  subsequent to electroplating of magnetic pole material  1602 .  FIG. 17  is a cross section view  1700  of  FIG. 16  subsequent to the planarization of the pole material  1602 . Intermediate steps (such as the deposition and removal of a CMP stop layer) have been omitted for simplicity, and are well known to those skilled in the art. Subsequent to pole material deposition, a nominal track width of TW (ref  1702 ) is obtained. TW is approximately the etched trench dimension TW′ (ref  1102 ) minus two time the thickness of the plating seed layer  1502 . After deposition and planarization of the pole material, the remainder of oxide 1 layer  402  is removed by RIE. 
         [0066]      FIG. 18  is a plan view  1800  of  FIG. 17  subsequent to the removal of oxide 1 layer  402  in accordance with a first embodiment of the present invention.  FIG. 19  is a cross section view  1900  through section H-H of  FIG. 18 . Due to the removal of oxide  1 , the notched interface of pole material  1602  (covered by plating seed layer  1502 ) is visible. The next step in the process is the blanket deposition of the gap layer. 
         [0067]      FIG. 20  is a cross section view  2000  of  FIG. 19  subsequent to the blanket deposition of gap layer  2002  in accordance with a first embodiment of the present invention. Gap layer  2002  is preferably a non-magnetic precious metal, typically Ru or Ru, but may also be a layer material comprising a under-layer of an insulator such as alumina, and an upper layer of Ru or Rh or other precious metal. Gap layer  2002  must not only serve as the magnetic gap between the pole and the shield, but also the plating seed layer for the deposition of the shield. After deposition of the gap layer  2002 , a photo resist layer is deposited. Following exposure and development, the patterned photo resist layer will act as the mask for shield plating. 
         [0068]      FIG. 21   a  is a plan view  2100  of  FIG. 20  subsequent to the deposition, imaging and development of photo resist layer  2102  in accordance with a first embodiment of the present invention.  FIG. 21   b  is a cross section view through section H-H of  FIG. 21   a .  FIG. 21   c  is a cross section view through section J-J of  FIG. 21   a . Photo resist layer  2102  is patterned to produce an opening recessed back from the cavities in oxide layer  602  by distance S 1  (ref  2106 ). The width of the cavity subsequent the deposition of the gap layer is dimension  2104 , which is approximately equal to dimension  502  minus 2 times the thickness of gap layer  2002 . The cavity bounded by layers  602 / 2002 ,  1602 / 2002 , and photo resist layer  2102  is then filled with magnetic alloy material by electroplating, utilizing gap layer  2002  as a seed layer. The resulting deposit of magnetic material forms the wrap around shield structure. Subsequent to shield plating, photo resist layer  2102  is removed, a blanket oxide layer deposited, and the entire structure planarized. Details of these processes have been omitted for clarity, but are well known to those skilled in the art. 
         [0069]      FIG. 22   a,b  are cross section views  2200 ,  2201  of  FIG. 21   b,c , respectively, subsequent to shield  2204  deposition in accordance with a first embodiment of the present invention. Photo resist layer  2102  has been removed and replaced with filler oxide layer  2202 , typically Al 2 O 3 . Subsequent to shield formation, the structure is lapped to form the precise location of the ABS, which then determines the throat height of the shield. 
         [0070]      FIGS. 23   a,b  are cross section views  2300 ,  2301  of  FIGS. 22   a,b , respectively, subsequent to lapping in accordance with a first embodiment of the present invention. Following the lapping process, the location of the ABS is finalized. Note that the shield  2204  has a stepped structure in regions on either side of the pole  1602 . These regions are referred to as the side shield. Above the pole layer  1602 , the shield has a depth (as measured from the ABS) of W 1  and a thickness Hal equal approximately to the thickness of filler oxide layer  2202 . In the side shield regions, the lower portion of the shield adjacent to the pole has a depth equal to the throat height TH 1  (ref  2302 ), and a depth above the pole layer  1602  equal to TH 1  plus dimension S 1  (ref  2106 ). The stepped structure aids in balancing the performance characteristics of the wrap around shield, such as improving saturation without reducing write pole signal strength. 
         [0071]    Returning to the process at  FIG. 17 ,  FIG. 24  is a cross section view  2400  of  FIG. 17  subsequent to blanket deposition of a second oxide 1 layer  2402 , etch mask layer  2404  and photo resist layer  2406  in accordance with a second embodiment of the present invention.  FIG. 25   a  is a plan view of  FIG. 24  subsequent to the patterning of mask layer  2404  and removal of a portion of oxide 1 layer  2402 , and the remaining sections of oxide 1 layer  402 , by RIE. The intermediate steps of imaging, developing, and removing photo resist layer  2406  have been omitted for clarity, but are self evident to those skilled in the art. The opening in patterned mask layer  2404  is recessed back from the cavities that contained oxide layer  402  by a dimension  2502 , exposing an underlying portion of oxide 2 layer  602 . 
         [0072]      FIG. 25   b  is a cross section view  2501  through section K-K of  FIG. 25   a  in accordance with a second embodiment of the present invention.  FIG. 25   c  is a cross section view  2503  through section L-L of  FIG. 25   a .  FIGS. 26   a,b  are cross section views  2600 ,  2601  of  FIG. 25   b,c , respectively, subsequent to the removal of mask layer  2404  and deposition of gap layer  2602  in accordance with a second embodiment of the present invention. Gap layer  2602  is preferably a non-magnetic precious metal, typically Ru or Ru, but may also be a layer material comprising a under-layer of an insulator such as alumina, and an upper layer of Ru or Rh or other precious metal. Gap layer  2602  must not only serve as the magnetic gap between the pole and the shield, but also the plating seed layer for the deposition of the shield. After deposition of the gap layer  2602 , a photo resist layer is deposited. Following exposure and development, the patterned photo resist layer will act as the mask for shield plating. 
         [0073]      FIGS. 27   a,b  are cross section views  2700 ,  2701  of  FIG. 26   a,b , respectively, subsequent to the deposition, imaging, and development of photo resist layer  2704  in accordance with a second embodiment of the present invention. Dimension S 3  (ref  2702 ) is equal to dimension  2502  plus the thickness of gap layer  2602 . 
         [0074]      FIGS. 28   a,b  are cross section views  2800 ,  2801  of  FIGS. 27   a,b , respectively, subsequent to the deposition of shield layer  2802  and deposition of filler oxide  2804  in accordance with a second embodiment of the present invention. Steps involving the planarization of filler oxide layer  2804  have been omitted for clarity, but are well known to those skilled in the art. 
         [0075]      FIG. 29   a,b  are cross section views  2900 ,  2901  of  FIGS. 28   a,b , respectively, subsequent to lapping in accordance with a second embodiment of the present invention. In this embodiment of the present invention, the addition of another oxide 1 layer  2402  creates an additional “step” in the wrap around shield structure. Thus, a stepped shield is created directly over the pole layer  1602  ( FIG. 29   a ) having a lower depth of W 1   2  (ref  2908 ) and an upper depth of W 2   2  (ref  2902 ), as measured from the ABS. In the side shield regions shown in  FIG. 29   b , a dual stepped structure is created, wherein the lower portion has a depth equal to the throat height TH 2  (ref  2910 ), a middle portion having a depth of W 1   2  (ref  2908 ), and an upper portion having a depth of W 2   2 , all measured from the ABS. Dimension S 2  (ref  2906 ) is equal to W 1   2  minus throat height TH 2 . The addition of another “step” in the structure of the wrap around shield, further improves saturation characteristics and write pole performance over that of the first embodiment of the present invention. 
         [0076]      FIG. 30  is a plan view  3000  of the finished structure of  FIGS. 29   a,b  and  23   a,b  in accordance with the first and second embodiments of the present invention. Filler oxide layer  3004  is equivalent to oxide layer  2202  of the first embodiment and  2804  in the second embodiment. Dimension W (ref  3002 ) is equivalent to W 1  (ref  2306 ) of the first embodiment and W 2   2  (ref  2902 ) of the second embodiment. 
         [0077]      FIG. 31  is a cross section view  3100  through section M-M of  FIG. 30  in accordance with the first and second embodiments of the present invention. This also the view looking into the structure from the ABS. Gap layer  3106  is equivalent to gap layer  2002  of the first embodiment and  2602  of the second embodiment. Wrap around shield  3006  corresponds to shield layers  2204  and  2802  of the first and second embodiments, respectively. 
         [0078]      FIG. 32  is a plan view  3200  through section N-N of  FIG. 31  in accordance with the first and second embodiments of the present invention. Throat height TH (ref  3202 ) is equivalent to TH 1  (ref  2302 ) of the first embodiment and TH 2  (ref  2910 ) of the second embodiment. The structure shows some unique advantages of the present invention. Firstly, there are two “flare points”, one located at a distance FP 1  (ref  3204 ) from the ABS, and another located at a distance FP 2  (ref  3206 ) from the ABS. The flare point located at FP 1  has the dominant impact on the magnetic properties of the write head. FP 2  has a secondary impact on the properties. The flare point at FP 1  is accurately located with respect to the ABS and the throat height TH of the shield due to the self aligned process used in fabrication. The structure also allows control of TW (ref  1702 ) independent of the location of the flare point at FP 1 . The TW is primarily determined by lithography and the REI etch performance of oxide  1 , whereas the location of the flare point at FP 1  is primarily determined by the interface between oxide  1  and oxide  2  (see  FIG. 7   a,b ), and the thickness of plating seed layer  1502  ( FIG. 15 ). 
         [0079]    The present invention is not limited by the previous embodiments heretofore described. Rather, the scope of the present invention is to be defined by these descriptions taken together with the attached claims and their equivalents.