Abstract:
A method for manufacturing a magnetic write head having a non-magnetic step layer, non-magnetic bump at the front of the non-magnetic step layer and a write pole with a tapered trailing edge. The tapered portion of the trailing edge of the write pole is formed by a two step process that allows the write pole taper to be formed with greater accuracy and repeatability than would be possible using a single step taper process. An alternative method is also described on how to make a non-magnetic bump structure with adjustable bump throat height prior to Damascene side shield gap formation in a Damascene wrap around shield head.

Description:
FIELD OF THE INVENTION 
     The present invention relates to magnetic heads for data recording, and more particularly to a method for manufacturing a perpendicular magnetic write head having a tapered write pole and a non-magnetic bump for optimal trailing shield spacing. 
     BACKGROUND OF THE INVENTION 
     The heart of a computer&#39;s long term memory is an assembly that is referred to as a magnetic disk drive. The magnetic disk drive includes a rotating magnetic disk, write and read heads that are suspended by a suspension arm adjacent to a surface of the rotating magnetic disk and an actuator that swings the suspension arm to place the read and write heads over selected circular tracks on the rotating disk. The read and write heads are directly located on a slider that has an air bearing surface (ABS). The suspension arm biases the slider toward the surface of the disk, and when the disk rotates, air adjacent to the disk moves along with the surface of the disk. The slider flies over the surface of the disk on a cushion of this moving air. When the slider rides on the air bearing, the write and read heads are employed for writing magnetic transitions to and reading magnetic transitions from the rotating disk. The read and write heads are connected to processing circuitry that operates according to a computer program to implement the writing and reading functions. 
     The write head has traditionally included a coil layer embedded in first, second and third insulation layers (insulation stack), the insulation stack being sandwiched between first and second pole piece layers. A gap is formed between the first and second pole piece layers by a gap layer at an air bearing surface (ABS) of the write head and the pole piece layers are connected at a back gap. Current conducted to the coil layer induces a magnetic flux in the pole pieces which causes a magnetic field to fringe out at a write gap at the ABS for the purpose of writing the aforementioned magnetic transitions in tracks on the moving media, such as in circular tracks on the aforementioned rotating disk. 
     In recent read head designs, a GMR or TMR sensor has been employed for sensing magnetic fields from the rotating magnetic disk. The sensor includes a nonmagnetic conductive layer, or barrier layer, sandwiched between first and second ferromagnetic layers, referred to as a pinned layer and a free layer. First and second leads are connected to the sensor for conducting a sense current there-through. The magnetization of the pinned layer is pinned perpendicular to the air bearing surface (ABS) and the magnetic moment of the free layer is located parallel to the ABS, but free to rotate in response to external magnetic fields. The magnetization of the pinned layer is typically pinned by exchange coupling with an antiferromagnetic layer. 
     The thickness of the spacer layer is chosen to be less than the mean free path of conduction electrons through the sensor. With this arrangement, a portion of the conduction electrons is scattered by the interfaces of the spacer layer with each of the pinned and free layers. When the magnetizations of the pinned and free layers are parallel with respect to one another, scattering is minimal and when the magnetizations of the pinned and free layer are antiparallel, scattering is maximized. Changes in scattering alter the resistance of the spin valve sensor in proportion to cos θ, where θ is the angle between the magnetizations of the pinned and free layers. In a read mode the resistance of the spin valve sensor changes proportionally to the magnitudes of the magnetic fields from the rotating disk. When a sense current is conducted through the spin valve sensor, resistance changes cause potential changes that are detected and processed as playback signals. 
     In order to meet the ever increasing demand for improved data rate and data capacity, researchers have recently been focusing their efforts on the development of perpendicular recording systems. A traditional longitudinal recording system, such as one that incorporates the write head described above, stores data as magnetic bits oriented longitudinally along a track in the plane of the surface of the magnetic disk. This longitudinal data bit is recorded by a fringing field that forms between the pair of magnetic poles separated by a write gap. 
     A perpendicular recording system, by contrast, records data as magnetizations oriented perpendicular to the plane of the magnetic disk. The magnetic disk has a magnetically soft underlayer covered by a thin magnetically hard top layer. The perpendicular write head has a write pole with a very small cross section and a return pole having a much larger cross section. A strong, highly concentrated magnetic field emits from the write pole in a direction perpendicular to the magnetic disk surface, magnetizing the magnetically hard top layer. The resulting magnetic flux then travels through the soft underlayer, returning to the return pole where it is sufficiently spread out and weak that it will not erase the signal recorded by the write pole when it passes back through the magnetically hard top layer on its way back to the return pole. 
     In a perpendicular magnetic recording system, it is desirable to maximize write field strength and also maximize field gradient. A strong write field ensures that a magnetic bit can be recorded in the magnetically hard top layer of the magnetic medium. A high field gradient allows for fast magnetic switching of the magnetic field from the write pole, thereby increasing the speed with which the magnetic transitions can be recorded. It is desirable to maximize both of these parameters, while also ensuring that the magnetic write pole does not become magnetically saturated at the pole tip. 
     SUMMARY OF THE INVENTION 
     The present invention provides a method for manufacturing a magnetic write head having a tapered write pole trailing edge, a non-magnetic step layer, and a non-magnetic bump structure for optimal trailing shield magnetic spacing. The method includes, first forming a magnetic write pole, then depositing a non-magnetic step layer over the write pole, the non-magnetic step layer having a front edge located a desired distance from an intended air bearing surface plane. A first ion milling is performed to form a first tapered portion on the write pole, and then a non-magnetic gap material is deposited A second ion milling is then performed to preferentially remove horizontally disposed portions of the non-magnetic gap material, leaving a non-magnetic bump over the front edge of the non-magnetic step layer. Then, a third ion milling is performed to form a second tapered portion on the write pole. 
     The two step process for forming the trailing edge taper allows for improved control of the location of the front edge of the non-magnetic bump structure. This is because the location of the front edge of the bump is determined by the location at which the first tapered portion of the write pole terminates. Then, after forming the bump (with its well defined front edge), the rest of the trailing edge taper can be formed. 
     The write pole can be formed by a damascene process wherein an opening is formed in a sacrificial RIEable fill layer. A non-magnetic track width reducing layer such as Ru can be deposited into the opening to reduce the width of the opening, and a magnetic material such as NiFe can be electroplated into the opening. 
     According to one method the fill layer can be removed after the trailing edge taper, step layer and non-magnetic bump have been formed. However, in another embodiment of the invention, the fill layer can be removed after the formation of the trailing edge taper, step layer and non-magnetic bump. 
     These and other features and advantages of the invention will be apparent upon reading of the following detailed description of preferred embodiments taken in conjunction with the Figures in which like reference numerals indicate like elements throughout. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a fuller understanding of the nature and advantages of this invention, as well as the preferred mode of use, reference should be made to the following detailed description read in conjunction with the accompanying drawings which are not to scale. 
         FIG. 1  is a schematic illustration of a disk drive system in which the invention might be embodied; 
         FIG. 2  is an ABS view of a slider, taken from line  2 - 2  of  FIG. 1 , illustrating the location of a magnetic head thereon; and 
         FIG. 3  is a cross sectional view of a magnetic write head according to an embodiment of the present invention; 
         FIG. 4  is an enlarged view of a pole tip region of the magnetic recording head of  FIG. 3 ; 
         FIG. 5  is an ABS view of the magnetic recording head of  FIGS. 3 and 4 ; 
         FIGS. 6-25 , are views of a portion of a magnetic write head in various intermediate stages of manufacture, illustrating a method for manufacturing a magnetic write head according to an embodiment of the invention; 
         FIGS. 26-32  are views of a portion of a magnetic write head in various intermediate stages of manufacture, illustrating a method for manufacturing a magnetic write head according to an alternate embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The following description is of the best embodiments presently contemplated for carrying out this invention. This description is made for the purpose of illustrating the general principles of this invention and is not meant to limit the inventive concepts claimed herein. 
     Referring now to  FIG. 1 , there is shown a disk drive  100  embodying this invention. As shown in  FIG. 1 , at least one rotatable magnetic disk  112  is supported on a spindle  114  and rotated by a disk drive motor  118 . The magnetic recording on each disk is in the form of annular patterns of concentric data tracks (not shown) on the magnetic disk  112 . 
     At least one slider  113  is positioned near the magnetic disk  112 , each slider  113  supporting one or more magnetic head assemblies  121 . As the magnetic disk rotates, the slider  113  moves radially in and out over the disk surface  122  so that the magnetic head assembly  121  may access different tracks of the magnetic disk where desired data are written. Each slider  113  is attached to an actuator arm  119  by way of a suspension  115 . The suspension  115  provides a slight spring force which biases slider  113  against the disk surface  122 . Each actuator arm  119  is attached to an actuator means  127 . The actuator means  127  as shown in  FIG. 1  may be a voice coil motor (VCM). The VCM comprises a coil movable within a fixed magnetic field, the direction and speed of the coil movements being controlled by the motor current signals supplied by controller  129 . 
     During operation of the disk storage system, the rotation of the magnetic disk  112  generates an air bearing between the slider  113  and the disk surface  122  which exerts an upward force or lift on the slider. The air bearing thus counter-balances the slight spring force of suspension  115  and supports slider  113  off and slightly above the disk surface by a small, substantially constant spacing during normal operation. 
     The various components of the disk storage system are controlled in operation by control signals generated by control unit  129 , such as access control signals and internal clock signals. Typically, the control unit  129  comprises logic control circuits, storage means and a microprocessor. The control unit  129  generates control signals to control various system operations such as drive motor control signals on line  123  and head position and seek control signals on line  128 . The control signals on line  128  provide the desired current profiles to optimally move and position slider  113  to the desired data track on disk  112 . Write and read signals are communicated to and from write and read heads  121  by way of recording channel  125 . 
     With reference to  FIG. 2 , the orientation of the magnetic head  121  in a slider  113  can be seen in more detail.  FIG. 2  is an ABS view of the slider  113 , and as can be seen the magnetic head including an inductive write head and a read sensor, is located at a trailing edge of the slider. The above description of a typical magnetic disk storage system, and the accompanying illustration of  FIG. 1  are for representation purposes only. It should be apparent that disk storage systems may contain a large number of disks and actuators, and each actuator may support a number of sliders. 
     With reference now to  FIG. 3 , the invention can be embodied in a magnetic head  302  having a tapered write pole and a non-magnetic bump. The write head  302  includes a magnetic write pole  304 , and a magnetic return pole  306 , both of which extend to an air bearing surface (ABS). A magnetic back gap layer  308  can be magnetically connected with the return pole  306  in a region removed from the ABS. However, the magnetic back gap  308  is optional. A magnetic shaping layer  310  can be connected with the back gap layer  308  and also with the write pole  304 . 
     In order to increase field gradient to increase the speed with which magnetization of the write field can be switched, a trailing magnetic shield  312  is provided at the ABS, adjacent to the trailing edge of the write pole. The trailing shield  312  is separated from the write pole  304  by a non-magnetic trailing gap layer  314 . A trailing return pole  316  can be provided to conduct magnetic flux from the trailing shield  312  to the shaping layer  310  and back gap  308 . 
     A non-magnetic, electrically conductive write coil  318  passes above and below the write pole  304  and shaping layer  310 . The write coil  318  (shown partially and in cross section in  FIG. 3 ) can be constructed of a material such as Cu, and when an electrical current flows through the write coil  318 , a resulting magnetic field causes a magnetic flux to flow through the return pole  306 , back gap  308  and write pole  304 . The write coil  318  can be encased within a non-magnetic, electrically insulating fill layer  320 , such as alumina and or hard baked photoresist, and can be formed on a non-magnetic, electrically insulating under-layer  322 , which also can be a material such as alumina. 
     The pole tip region of the write pole  314  can be seen more clearly with reference to  FIG. 4 , which shows an enlarged view of the pole tip portion of the write pole  304  and surrounding structure. A non-magnetic step layer  402  is formed over the write pole  304 , and can be constructed primarily of non-magnetic materials such as NiCr or Cr. This non-magnetic step layer  402  is also a trailing edge taper mask, as will become clearer below, and may include a hard mask layer such as SiC or diamond like carbon (DLC) which will be discussed in greater detail below. 
     The non-magnetic step layer  402  has a front edge  406 , at an end closest to the ABS that may be slightly tapered backward relative to the ABS. A non-magnetic bump layer  404  is formed at the front edge  406  of the magnetic step layer  402 . The front edge  406  is recessed from the ABS by a desired amount. The desired dimension of the front edge recess (distance between the ABS and the front edge  406 ) is between 100-250 nm. The distance between the front edge of non-magnetic bump  404  to ABS is about 50-150 nm. The flare point of the write pole is about 50-120 nm. 
     As can be seen, the write pole  304  has a tapered or sloped trailing edge having a taper portion  410  between the nonmagnetic step and the ABS. As can be seen, the trailing edge taper  410  terminates at the front edge  406  of the non-magnetic step layer  402 . This is a result of manufacturing processes that will be described further below. 
     The presence of the non-magnetic step layer  402  helps to reduce magnetic flux loss between the pole tip portion of the write pole  304  and the trailing shield  312 . The tapered trailing edge portion,  412  further promotes the focusing of magnetic flux to the pole tip while avoiding magnetic saturation of the pole tip portion of the write pole  304 . 
     The trailing magnetic shield  312  helps to increase the field gradient of the magnetic write field  414  emitted from the tip of the write pole  304 . This increase in field gradient helps to define a shaper written transition, thereby improving signal-to-noise ratio and increasing data density. 
     Optimal functioning of the trailing shield involves a tradeoff between maximizing field gradient improvements and minimizing the loss of write field to the trailing shield. The write head is preferably designed so as to prevent magnetic saturation of the trailing shield  312 . In addition, the spacing between the write pole  402  and the trailing shield  312  is preferably such that the write field is maximized at the tip of the write pole  402 , and also such that little write field leaks from the write pole  402  to the trailing shield  312 . 
     The present invention optimizes both of these goals. The write gap  314  has a thickness “T” that provides a desired spacing between the write pole  304  and the trailing shield  312  at the pole tip. This spacing T can therefore be controlled by controlling the as deposited thickness of the trailing gap layer  314 . 
     The location of the front edge  406  of the magnetic step layer  402 , as well as the initiation point of the steep tapered trailing edge portion  410  of the write pole  304 , are critical regions for the leakage of flux from the write pole  304  to the trailing shield. This is because of the sudden channeling of magnetic flux from the write pole  304  into a much smaller pole tip portion of the write pole  304 . In order to prevent the leakage of magnetic flux at this point, the non-magnetic bump  404  and the non-magnetic step  402  advantageously increases the magnetic spacing between the trailing shield  312  and the write pole  304 . As can be seen, the spacing between the write pole  304  and the trailing shield  312  at this point is the sum of the thickness of the bump  404  and the thickness of the gap layer  314  in the region immediately in front of the step  402 , and the spacing is the sum of the step  402  and the thickness of the gap layer  314  behind the step  402 . The non-magnetic bump  404  can be constructed of a material such as alumina and can be formed by a manufacturing process that will be described in greater detail herein below. 
       FIG. 5  shows an enlarged view of a portion of the write head  302  as viewed from the air bearing surface ABS. As can be seen, the write pole  304  as viewed from the ABS has a narrow, trapezoidal shape. In fact, the tip of the write pole  304  is so narrow that is nearly resembles a triangular shape, having a leading edge  506  that is extremely small (smaller than the trailing edge  508 ), the leading edge  506  of the write pole  304  defining the track width of the write pole  304 . Also as can be seen in  FIG. 5 , the trailing shield  312  is actually a wrap-around trailing shield, having side portions  510 ,  512  that extend down the sides of the write pole  304 . The side portions  510 ,  512  of the shield  312  are separated from the write pole  304  by first and second side gap layers  502 ,  504  that can be constructed of a non-magnetic material such as alumina. The construction of the write pole  304 , side gaps  502 ,  504 , trailing gap  314  and shield  312  will be described in greater detail below. 
       FIGS. 6-25  illustrate a method for manufacturing, a magnetic write head according to an embodiment of the invention. With reference to  FIG. 6 , a substrate  602  is provided. This substrate  602  can include the insulating fill layer  320  and shaping layer  310  of  FIG. 3 . A layer of material that is resistant to reactive ion etching (RIE stop layer)  604  is deposited over the substrate  602 . The RIE stop layer can be a material such as Cr, NiCr, Ru, etc. Then, a non-magnetic RIEable material  606  such as SiO 2  or alumina (Al 2 0 3 ) is deposited over the RIE stop layer. The RIEable fill layer is deposited to a sufficient thickness to form a write pole therein, as will become apparent below. 
     With reference now to  FIG. 7 , a bi-layer photoresist mask structure  702  is formed over the RIEable fill layer  606 . The mask  702  is configured to define a write pole shape, as will become apparent below. Then, a RIE hard mask layer  704  is deposited over the fill layer  606  and mask  702 . The hard mask layer  704  can include one or more of, Ta, Cr, NiCr, etc. 
     The mask structure  702  can be lifted off, and then a reactive ion etching (RIE) can be performed to remove portions of the fill layer  606  that are not protected by the RIE hard mask  704 . The RIE is preferably performed in such a manner to form a trench with tapered side walls in the fill layer  606  as shown in  FIG. 8 . Then, with reference to  FIG. 9  a non-magnetic track width reducing layer  802  can be deposited to reduce the width of the trench formed in the fill layer  606 . The track-width reducing layer  802  can be a material such as ALD Al 2 O 3  or ALD Ru. Then, a magnetic material  1002  can be electroplated, and a chemical mechanical polishing (CMP) can be performed, leaving a structure such as that shown in  FIG. 10 , with a write pole  1002  formed by the above described damascene process. As can be seen, the write pole is embedded in the track width reducing layer  802 , which as mentioned above can be Al 2 O 3  or Ru. 
     With reference now to  FIG. 11 , a non-magnetic step layer  1101  is deposited over the write pole  1102  and layers  606  and  802 . The non-magnetic step layer  1101  can be a material such as NiCr, Ru or Ir, and can be deposited to a thickness of about 50 to 200 nm. A milling mask layer  1102  constructed of a material such as SiC or Al 2 O 3  is then deposited over the non-magnetic step layer  1101 , and can be deposited to a thickness of about 50 to 300 nm. A thinner RIE hard mask  1104  is then deposited over the milling mask layer  1102 . The RIE hard mask layer  1104  can be constructed of a material such as Cr, NiCr and can be deposited to a thickness of about 5 to 100 or about 30 nm. 
     With reference now to  FIG. 12 , a photoresist mask  1202  is formed over the RIE hard mask  1104 . The photoresist mask  1202  is patterned to define a desired step, and its shape can be seen more clearly with reference to  FIG. 13 , which shows a top down view as shown from lines  13 - 13  of  FIG. 12 . In the view of  FIG. 13 , the write pole  1002  is shown in dashed line to indicate that it is hidden beneath layers  1101 ,  1102 ,  1104  ( FIG. 12 ). As shown in  FIG. 13 , the write pole  1002  has a flare point  1302  and the photoresist layer  1202  has a front edge  1304  that is behind the flare point  1302 . 
     With reference now to  FIG. 14 , an ion milling is performed to transfer the image of the photoresist layer  1202  onto the underlying hard mask layer  1104 . The photoresist layer can then be lifted off, leaving a structure as shown in  FIG. 15 . Then, a reactive ion etching (RIE) is performed to remove portions of the milling mask layer  1102  that are not protected by the hard mask  1104 , leaving a structure as shown in  FIG. 16 . 
     A first ion milling is then performed to remove portions of the step layer  1101 , and track width reducing layer  802  that are not protected by the mask layers  1102 ,  1104 , leaving a structure as shown in  FIG. 17 . This first ion milling is preferably performed at normal or near normal to the plane of the deposited layers, and as can be seen, the first ion milling is terminated when the RIEable fill layer  606  has been reached.  FIG. 18 , shows a cross sectional view, taken from line  18 - 18  of  FIG. 17 . 
     With reference now to  FIG. 19 , a second ion milling is performed to form a first taper to the trailing edge of the magnetic write pole material  1002 . This second ion milling is preferably performed at an angle relative to normal so that shadowing from the layers  1101 ,  1102  causes the second ion milling to form a tapered surface  1902  on the magnetic write pole layer  1002 . The tapered surface  1902  preferably forms and angle  1904  that is 20 to 40 degrees or about 35 degrees relative to horizontal (i.e. relative to the as deposited surface planes of the layers  604 ,  802 ,  1102 ,  1101 ,  1102 . It can be seen, in  FIG. 19  that the tapered portion  1902  of the surface of the magnetic write pole layer  1002  terminates short of the air bearing surface, the location of the intended air bearing surface plane being indicated in  FIG. 19  by the dashed line denoted as (ABS). This will form a first tapered portion of the write pole layer  1002 , a second portion being formed as described herein below. It can also be seen that an additional portion of the mask layer  1102  is consumed by the second ion milling, such that the layer  1102  is thinner in  FIG. 19  than it is in  FIG. 18 . 
     While the first and second ion milling operations have been described above as separate ion milling operations, in an alternate method, the first and second ion millings can be combined into a single ion milling operation. In this case, the single, combined ion milling would be used both to pattern the image of layer  1102  onto layer  1101 , and also to form the tapered surface  1902  on the layer  1002 . 
     After the second ion milling (or combined first and second ion millings) a reactive ion etching is performed to remove the RIEable fill layer  606  ( FIG. 17 ) leaving a structure such as that shown in  FIG. 20 , which shows a cross sectional view of a plane parallel with the air bearing surface (ABS). If the fill layer  606  is alumina rather than a material such as SiO 2 . Then, a wet etch can be used to remove the fill layer  606 . 
     Then, a thick layer of alumina  2102  is deposited by a conformal deposition method such as Atomic Layer Deposition (ALD). This alumina layer  2102  can be deposited to a thickness of about 30 to 150 nm or about 60 nm. Then, a third ion milling (ALD ion milling) is performed to remove a portion of the alumina layer  2102 . This ALD ion milling preferentially removes horizontally disposed portions of the alumina layer, leaving alumina side walls  2102  as shown in  FIG. 22 . This ion milling also leaves an alumina bump layer  2302  as shown in  FIG. 23 . This alumina bump layer is formed on the front edge  2304  of the layers  1101 ,  1102 . As can be seen, in  FIG. 23 , the transition from the tapered surface  1902  of layer  1002  to the relatively flat surface  2306  of the layer  1002  occurs before the ABS. That is, the taper  1902  does not extend to the ABS. 
     Then, yet another ion milling (fourth ion milling or second taper ion milling) is performed to finish forming the taper on the trailing edge of the magnetic write pole layer  1002 . It will be recalled that the previously performed ion milling formed the first taper portion  1902 . This taper portion  1902  terminated short of the ABS. The non-magnetic, alumina bump layer  2302  now covers this first taper portion  1902 . The second ion milling forms a second taper portion  2402  that extends beyond the ABS plane, the alumina bump layer  2302  protecting the first taper portion  1902  during this fourth (second taper) ion milling. This ion milling is preferably performed at an angle and in such a matter as to for the second taper  2402  with an angle of 20-40 degrees or about 35 degrees relative to the surface of the layers  602 ,  604 ,  802 ,  1002 ,  1101 . 
     Forming the taper portions  1902 ,  2402  in the above described two step process provides distinct advantages. For example, the location of the front end of the non-magnetic bump can be easily controlled. As will be recalled, the ALD milling process described above that was used to form the non-magnetic bump preferentially removed horizontally disposed portions of the alumina layer  2302 . This means that the front edge of the alumina bump  2302  terminated at the front edge of the first taper portion  1902 . This allows for accurate control of the front edge of the alumina bump  2302 . The above process provides improved process repeatability and control of the location of the front edge of the bump  2302 . 
     With reference now to  FIG. 25 , a non-magnetic, electrically insulating layer is deposited. This layer  2502  is deposited. This layer  2502  serves as both a trailing gap layer and an electroplating seed. Therefore, the layer  2502  is deposited to a thickness of a desired trailing gap. Then, an electroplating frame mask (not shown) is formed and a magnetic material  2504  such as CoFe or NiFe is deposited by electroplating to form a wrap-around, trailing magnetic shield, corresponding to the shield  312  of  FIGS. 3 ,  4  and  5 . 
     With reference now to  FIGS. 26-33  another embodiment for constructing a magnetic head according to an embodiment of the invention is disclosed.  FIG. 26  show a structure such as that shown in  FIGS. 17 and 18  above. An ion milling process is performed to form a tapered surface  1902  on the write pole  1002 , resulting in a structure such as that shown in  FIG. 27 . The tapered portion  1902  can extend a distance  2702  of 50 to 350 nm from the step layer  1101 , and the front edge of the step layer  1101  can extend a distance of 200 to 300 nm from the intended air bearing surface plane (ABS). This means that tapered portion can terminate in front of or behind the ABS plane. 
     With reference now to  FIG. 28 , a layer of alumina  2802  is deposited, preferably by atomic layer deposition (ALD). The alumina layer  2802  is preferably deposited to a thickness of 100-200 nm or about 150 nm. Alternatively, the layer  2808  can be some other non-magnetic material such as Ru. An ion milling procedure can then be performed to preferentially remove horizontally disposed portions of the ALD material  2802 , leaving a non-magnetic bump structure  2902  as shown in  FIG. 29 , which is a cross sectional view taken from line  29 - 29  of  FIG. 28 , but shown after the ion milling. The non-magnetic bump layer  2902  can extend a distance of 50-150 nm from the front edge of the step layer  1101 . This ion milling also leaves ALD side walls  3002  as shown in  FIG. 30 ,  FIG. 30  being a view of a plane that is parallel with the ABS. The side walls  3002  are formed of the same ALD layer  2802  deposited above with reference to  FIG. 28 , as is the bump layer  2902 . After the non-magnetic bump  2902  has been formed, another ion milling can be performed to further continue the taper of the trailing edge of the write pole  1002 , as described above with reference to  FIG. 24 . 
     After the bump  2902  and taper  1902  have been formed as shown in  FIG. 29 , non-magnetic side walls can be formed at the sides of the write pole. The Ru layer  802  provides some side wall gap, but generally a larger gap will be desired.  FIG. 31  shows a view of the structure so far as viewed from a plane parallel with and near the ABS plane. The step structures  1101 ,  1102  ( FIG. 30 ) are not shown in  FIG. 31 , because those structures are located further back away from the ABS. As can be seen, in  FIG. 31 , the fill layer  606  still remains. This fill layer  606  can be alumina (Al 2 O 3 ) or can be SiO 2 . At least a couple of methods are available for removing this till material and leaving a non-magnetic side wall. A remaining portion of the fill layer  606  can be used to provide the added non-magnetic side wall gap. 
     With reference to  FIG. 32 , a mask structure  3202  is formed over the write pole structure  1002 . A reactive ion etching can be performed to remove portions of the fill layer  606  that are not protected by the mask  3202 . Therefore, the mask  3202  defines the width of the side gap. After forming the bump and side gap layers as described above, a trailing gap and trailing shield can be formed as described above with reference to  FIG. 25 . 
     While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Other embodiments falling within the scope of the invention may also become apparent to those skilled in the art. Thus, the breadth and scope of the invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.