Abstract:
A method of forming a head comprises forming a write transducer on a wafer, cutting the wafer to produce a slider bar with a cut surface, and planarizing the cut surface of the slider bar. Forming the write transducer can include forming a first pole layer and forming a first pole pedestal layer over the first pole layer, where the first pole pedestal layer includes a tapered portion defined by a first end having a nose width less than a desired final nose width, and a second end having a zero throat width greater than the desired final nose width. Planarizing the cut surface of the slider bar exposes the first pole pedestal layer until a width thereof approximately equals the desired final nose width.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a divisional of U.S. application Ser. No. 10/013,431 filed on Dec. 11, 2001, now U.S. Pat. No. 6,829,819, which is a divisional of U.S. application Ser. No. 09/304,224 filed on May 3, 1999, now abandoned, and claims priority therefrom pursuant to 35 U.S.C. § 120. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This divisional application relates generally to magnetic disk data storage systems, and more particularly to methods for making magnetic write transducers. 
   2. Description of the Background Art 
   Magnetic disk drives are used to store and retrieve data for digital electronic apparatuses such as computers. In  FIGS. 1A and 1B , a magnetic disk data storage systems of the prior art includes a sealed enclosure  12 , a disk drive motor  14 , a magnetic disk  16 , supported for rotation by a drive spindle S 1  of motor  14 , an actuator  18  and an arm  20  attached to an actuator spindle S 2  of actuator  18 . A suspension  22  is coupled at one end to the arm  20 , and at its other end to a read/write head or transducer  24 . The transducer  24  (which will be described in greater detail with reference to  FIG. 2A ) typically includes an inductive write element with a sensor read element. As the motor  14  rotates the magnetic disk  16 , as indicated by the arrow R, an air bearing is formed under the transducer  24  causing it to lift slightly off of the surface of the magnetic disk  16 , or, as it is termed in the art, to “fly” above the magnetic disk  16 . Alternatively, some transducers, known as “contact heads,” ride on the disk surface. Various magnetic “tracks” of information can be written to and/or read from the magnetic disk  16  as the actuator  18  causes the transducer  24  to pivot in a short arc as indicated by the arrows P. The design and manufacture of magnetic disk data storage systems is well known to those skilled in the art. 
     FIG. 2A  depicts a magnetic read/write head  24  including a substrate  25  above which a read element  26  and a write element  28  are disposed. Edges of the read element  26  and write element  28  also define an air bearing surface ABS, in a plane  29 , which can be aligned to face the surface of the magnetic disk  16  (see  FIGS. 1A and 1B ). The read element  26  includes a first shield  30 , an intermediate layer  32 , which functions as a second shield, and a read sensor  34  that is located within a dielectric medium  35  between the first shield  30  and the second shield  32 . The most common type of read sensor  34  used in the read/write head  24  is the magnetoresistive (AMR or GMR) sensor, which is used to detect magnetic field signals from a magnetic medium through changing resistance in the read sensor. 
   The write element  28  is typically an inductive write element, which includes the intermediate layer  32 , which functions as a first pole, and a second pole  38  disposed above the first pole  32 . The first pole  32  and the second pole  38  are attached to each other by a backgap portion  40 , with these three elements collectively forming a yoke  41 . Above and attached to the first pole  32  at a first pole tip portion  43 , is a first pole pedestal  42  abutting the ABS. In addition, a second pole pedestal  44  is attached to the second pole  38  at a second pole tip portion  45  and aligned with the first pole pedestal  42 . This area including the first and second poles  42  and  44  near the ABS is sometimes referred to as the yoke tip region  46 . A write gap  36  is formed between the first and second pole pedestals  42  and  44  in the yoke tip region  46 . The write gap  36  is filled with a non-magnetic material. This non-magnetic material can be either integral with (as is shown here) or separate from a first insulation layer  47  that lies below the second pole  38  and extends from the yoke tip region  46  to the backgap portion  40 . Also included in write element  28  is a conductive coil  48 , formed of multiple winds  49 , that is positioned within a dielectric medium  50  that lies above the first insulation layer  47 . As is well known to those skilled in the art, these elements operate to magnetically write data on a magnetic medium such as a magnetic disk  16 . 
   More specifically, an inductive write head such as that shown in  FIGS. 2A–2C  operates by passing a writing current through the conductive coil layer  48 . Because of the magnetic properties of the yoke  41 , a magnetic flux is induced in the yoke  41  by write currents that are passed through the coil layer  48 . The write gap  36  allows the magnetic flux to fringe out from the yoke  41  (thus forming a fringing gap field) and to cross a magnetic recording medium that is placed near the ABS. A critical parameter of a magnetic write element is a trackwidth of the write element, which determines a magnetic write width (MWW), and therefore drives the recording track density. For example, a narrower trackwidth can result in a narrower MWW and a higher magnetic recording density. The trackwidth is affected by geometries in the yoke tip portion  46  (see  FIG. 2A ) at the ABS. These geometries can be better understood with reference to  FIG. 2B , a view taken along line  2 B— 2 B of  FIG. 2A . 
   As can be seen from  FIG. 2B , the first and second poles  32 ,  38  can have different widths W 1 , W 2  respectively in the yoke tip portion  46  (see  FIG. 2A ). In the shown configuration, the trackwidth of the write element  28  is defined by the width Wp of the second pole pedestal  44 . As can be better seen from the plan view of  FIG. 2C  taken along line  2 C— 2 C of  FIG. 2B , the width Wp of the pole pedestals typically is substantially uniform. The gap field of the write element also can be affected by the throat height TH, which is measured from the ABS to the zero throat ZT, as shown in  FIG. 2A . Thus, accurate definition of the both trackwidth and throat height is critical during the fabrication of the write element. 
   However, the control of trackwidth and throat height can be limited with typical fabrication processes, such as masking and plating at the wafer level. For example, the trackwidth sigma σ tw , can be limited to a minimum of 0.07 microns. These problems are further aggravated with increasing topography over which the trackwidth-defining element is formed. Such topography is created by the various heights of other elements that have been formed before the trackwidth-defining element is formed. Greater trackwidth control can be attempted using other processes such as focused ion beam (FIB) milling, however such processes can be expensive. Alternatively, the trackwidth can be defined by the first pole width W 1 . However, such processes can also be expensive, complex, and result in lower production yields. 
   It can also be very difficult and expensive to form very small trackwidths using typical processes. Therefore, forming a pole pedestal having a trackwidth of about 1.25 microns can be very difficult and expensive, with smaller trackwidths posing even greater challenges. When demand for higher density writing capabilities drives smaller trackwidths, this aspect of fabrication becomes increasingly problematic. 
   An additional disadvantage of some current write element configurations, such as those shown in  FIGS. 2A–2C , is a secondary pulse phenomenon that can degrade recording performance. Typically, an intended primary pulse is generated to record a single bit of data. However, due to magnetic saturation at the interface between the second pole pedestal  44  and the second pole tip portion  45 , an unintended second pulse may be produced just after the primary pulse. As linear density increases, in other words, as one attempts to write bits closer together and primary pulses follow one another more closely, this second pulse effect may distort the waveforms of the primary pulses. Such distortions generated by the prior art write elements shown in  FIGS. 2A–2C  when operated at high linear densities makes them unsuitable for high density magnetic recording applications. 
   Accordingly, what is desired is a write element that is effective for applications having data densities on the order of 40 Gbits/in 2  with a trackwidth of less than about 1 micron and exhibiting substantially no secondary pulse phenomenon. Further, it is desired to achieve these qualities inexpensively, easily, and while maximizing throughput. 
   SUMMARY OF THE INVENTION 
   The present invention provides a method of forming a head such as a read/write head. The read/write head can be, for example, an MR head. An exemplary embodiment of the method comprises forming a write transducer on a wafer, cutting the wafer to produce a slider bar with a cut surface, and planarizing the cut surface of the slider bar. More specifically, forming the write transducer can include forming a first pole layer and forming a first pole pedestal layer over the first pole layer, where the first pole pedestal layer includes a tapered portion defined by a first end having a nose width less than a desired final nose width, and a second end having a zero throat width greater than the desired final nose width. In this exemplary embodiment, planarizing the cut surface of the slider bar exposes the first pole pedestal layer until a width thereof approximately equals the desired final nose width. 
   In some embodiments of the present invention, forming the write transducer further includes forming a second pole pedestal layer over the first pole pedestal layer, where the second pole pedestal layer includes a tapered portion. In some of these embodiments planarizing the cut surface of the slider bar further includes exposing the second pole pedestal layer. 
   In some embodiments of the present invention the method can also comprise forming a read transducer on the wafer. The read transducer can include, for example, a magnetoresistive element. In such embodiments planarizing the cut surface of the slider bar can further define a stripe height of the magnetoresistive element. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is a partial cross-sectional front elevation view of a magnetic data storage system; 
       FIG. 1B  is a top plan view taken along line  1 B— 1 B of  FIG. 1A ; 
       FIG. 2A  is a cross-sectional side view of a prior art read/write head of the magnetic disk drive assembly of  FIGS. 1A and 1B ; 
       FIG. 2B  is an ABS view taken along line  2 B— 2 B of  FIG. 2A ; 
       FIG. 2C  is a plan view taken along line  2 C— 2 C of  FIG. 2A ; 
       FIG. 3  is a perspective view of a pole tip portion of a write element, according to an embodiment of the present invention; 
       FIG. 4A  is a plan view of the pole tip portion of the write element, taken along line  4 — 4  of  FIG. 3 , according to an embodiment of the present invention; 
       FIG. 4B  is a plan view of a wafer-level write element, according to an embodiment of the present invention; 
       FIG. 5  is a plan view of a second pole pedestal and read sensor of a read/write head, according to an embodiment of the present invention; 
       FIG. 6  depicts and representative graph of the magnetic writing field strength according to an embodiment of the present invention as compared to the prior art; 
       FIG. 7  is a process diagram of a method for forming a write element, according to an embodiment of the present invention; and 
       FIG. 8  is a process diagram of a method for forming a write element, according to another embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1A ,  1 B, and  2 A– 2 C have been described above with reference to the prior art. 
     FIG. 3  is a perspective view of a pole tip portion of a write element  60 , according to an embodiment of the present invention. The write element  60  includes a first pole  62  and second pole  64 , formed of a magnetic material, similar to those of the prior art. A first pole pedestal  66  is also formed of magnetic material and is magnetically connected to the first pole  62 . A second pole pedestal  68  formed of magnetic material is magnetically connected to the second pole  64 . Also, the first pole  62  includes a first pole first surface  70  which forms a portion of the air bearing surface ABS. A first pole pedestal first surface  72 , and a second pole pedestal first surface  74  are also included in the air bearing surface ABS, along with a second pole first surface  76 . The first pole pedestal  66  and second pole pedestal  68  are disposed between the first pole  62  and the second pole  64  and further define a write gap  71  therebetween. As in the prior art, the write gap  71  can be filled with non-magnetic, electrically insulating material (not shown). However unlike the prior art, the first and second pole pedestals  66 ,  68  have a tapered shape that can be better understood with reference to  FIG. 4  and the related discussion below. 
     FIG. 4A  is a plan view of the write element  60  taken along line  4 A— 4 A of  FIG. 3 . As can be better seen with reference to  FIG. 4A , in an ABS portion  80  of the second pole pedestal  68  that is proximate the air bearing surface ABS, a second pole pedestal width W P2P  increases with increasing distance D from the ABS. Therefore, the second pole pedestal width W P2P  at the ABS is the most narrow portion of the second pole pedestal  68 . The shape of the second pole pedestal  68  away from ABS is also important since it affects the throat height as well as the trackwidth definition. Compared with conventional pole pedestals with rectangular shapes, such as those shown in  FIGS. 2A–2C , the second pole pedestal  68  of an exemplary embodiment of the present invention utilizes a greater volume of magnetic material. This greater volume of magnetic material significantly reduces the magnetic saturation at the interface between the second pole  64  and second pole pedestal  68 , thereby substantially eliminating second pulse effects. As previously noted, removing second pulse effects can lead to increased writing performance which may be necessary for achieving high density magnetic recording. 
   A physical trackwidth of the write element  60  can be defined with much smaller dimensions that can be typically obtained with processes and techniques of the prior art. In particular, the second pole pedestal ABS width W P2P ABS  can be defined with very small values to define the physical trackwidth of the write element  60 . To better understand how such small widths of the second pole pedestal  68  ca be achieved,  FIG. 4B  shows a plan view of the wafer-level write element  84 . 
   As shown in  FIG. 4B , at the wafer level the first pole  62 , second pole  64 , first pole pedestal  66 , and second pole pedestal  68  each extends beyond an ABS plane  79  within which an air bearing surface ABS is desired to be exposed. This air bearing surface ABS is exposed by cutting the wafer that includes the write element  84  along one or more planes that are substantially parallel to the ABS plane  79 , to thereby form one or more individual slider bars. The cut surface of such a slider bar is then lapped until the air bearing surface ABS is exposed. Thus, those portions of the first pole  62 , second pole  64 , first pole pedestal  66 , and second pole pedestal  68  that extend beyond the ABS plane  79  at the wafer level, are removed during this lapping process. 
   When the write element  84  is incorporated with a read element that includes a read sensor  86 , the read sensor  86  may also include a portion that extends beyond the ABS plane  79  and that is removed during the above-described lapping. Typically, the stripe height SH of the read sensor  86  can be accurately defined in this way. For example, the stripe height can be defined to within a stripe height tolerance σ SH  of no more than about 5 μins. Because of this lapping accuracy, the throat height TH of the second pole pedestal  86 , defined as the distance between the air bearing surface ABS and the zero throat ZT, can also be accurately defined during the same lapping process. Advantageously, because of this accuracy and the tapered geometry of the second pole pedestal  68 , the second pole pedestal ABS width W P2P ABS  can also be more accurately defined than in the prior art. Further, because of the accuracy of this width definition, smaller such widths can be defined than in the prior art. In addition, the first pole pedestal  66  can be similarly formed with similarly accurate definition of an ABS width. Of course, in some embodiments, the first pole pedestal  66  is not tapered, and alternatively may have a substantially uniform width with increasing distance away from the air bearing surface ABS. 
   The control of the ABS width definition with tapered pole pedestals can be better understood with reference to  FIG. 5 .  FIG. 5  depicts a plan view of the second pole pedestal  68  and the read sensor  86 . In this figure, the dashed lines depict the structures at the wafer level prior to lapping, while the solid lines depict the structures after the air bearing surface ABS has been exposed through lapping. When the taper angle θ and zero throat width W ZT  of the second pole pedestal is substantially known, the ABS width W P2P ABS  can be determined as a function of the throat height TH. Further, when the offset height OSH (defined as the difference between the throat height TH and the read sensor  86  stripe height SH) is known, the ABS width W P2P ABS  can further be determined as a function of the stripe height SH. More particularly, the second pole pedestal ABS width W P2P ABS  can be defined by the following equation:
 
 W   P2P ABS   =W   ZT −2( TH )(tanθ)= W   ZT −2( OSH+SH )(tanθ).
 
   Thus, as the stripe height SH is accurately defined by lapping, the throat height TH, and therefore the ABS width W P2P ABS  are also accurately defined. These improvements provide a trackwidth that is both narrower and better defined than previously achievable by the prior art, leading to higher write performance. The effect on write performance of this more accurately defined and narrower ABS width W P2P ABS  can be seen with reference to the graph in  FIG. 6 . The graph depicts gap field profiles in the direction of the trackwidth for both an embodiment of the present invention and for a typical design of the prior art. 
   As can be seen from  FIG. 6 , the magnetic write width MWW of an exemplary embodiment of the present invention can be less than that of the prior art, and further include narrower erase bands. For example, whereas the prior art typically can have a magnetic write width MWW on the order of about 1.25 μm, the write element of an exemplary embodiment of the present invention, incorporating a tapered first pole pedestal and a tapered second pole pedestal, can obtain a magnetic write width on the order of about 0.2 μm to about 1 μm. Furthermore, while the prior art erase bandwidth EB PA  can be on the order of about 0.3 μm to about 0.5 μm when no pole pedestals are included, the erase bandwidth EB 1  of an exemplary embodiment of the present invention can be limited to within the range of about 0.05 μm to about 0.1 μm by the inclusion of tapered first and second pole pedestals. Thus, with these reduced magnetic write widths MWW and erase bandwidths, significantly higher data densities can be obtained in recording of data on a magnetic media. For example, densities on the order of 40 Gbits/in 2  can be achieved. 
     FIG. 7  depicts a process diagram for a method  100  for forming a write element according to an embodiment of the present invention. In operation  102 , a first pole is provided. The first pole can be formed of a magnetic material, such as Permalloy. In addition, the first pole can be provided above a substrate, or alternatively above a read element. The first pole of operation  102  otherwise can be provided as a second shield of a read element. Operation  104  includes forming a tapered first pole pedestal that is magnetically connected to the first pole provide in operation  102 . The first pole pedestal can be formed of a magnetic material, similar to or the same as the material of the first pole of operation  102 . In operation  104 , a backgap portion can also be formed above and magnetically connected to the first pole of operation  102 , distal the tapered first pole pedestal. 
   A first insulation layer is formed in operation  106  above the first pole of operation  102 , and between the tapered first pole pedestal and the backgap portion. Importantly, the first insulation layer of operation  106  leaves at least a portion of the tapered first pole pedestal and the backgap portion exposed. In operation  108 , a write gap layer is formed above the exposed surface of the tapered first pole pedestal. 
   A tapered second pole pedestal is formed in operation  110  above and aligned with the tapered first pole pedestal of operation  104 . Thus, the write gap layer of operation  108  is disposed between the tapered first pole pedestal and the tapered second pole pedestal. In alternative embodiments, the first insulation layer of operation  106  can be integral with the write gap layer of operation  108 , and can be formed in essentially the same operation. A second insulation layer is formed in operation  112 , between the tapered second pole pedestal and the back gap portion of operation  104 . Importantly, a portion of the tapered second pole pedestal and a portion of the backgap portion remains exposed. 
   In operation  114 , a coil embedded in a third insulation layer is formed above the second insulation layer. Also, in operation  116 , a second pole is fanned above the third insulation layer and magnetically connected to both the tapered second pole pedestal of operation  110  and the backgap portion of operation  104 . The tapered first pole pedestal, tapered second pole pedestal, and second pole each can be formed using known methods, such as by masking and plating magnetic materials, followed by mask lift off. The first, second, and third insulation layers of operations  106 ,  112 , and  114 , respectively, can be formed of any suitable non-magnetic, electrically insulating material, such as alumina. In some alternative embodiments, one or more of these insulation layers can be formed of cured photoresistive material. 
     FIG. 8  depicts a process diagram for a method  120  for forming a write element, according to another embodiment of the present invention. A first pole formed of magnetic material is provided in operation  122 . In operation  124 , the first pole of operation  122  is chemically-mechanically polished (CMP). The CMP operation forms a substantially planar upper surface of the first pole of operation  122 . Above this substantially planar upper surface, a tapered first pole pedestal is formed in operation  126 . More particularly, the tapered first pole pedestal is formed of magnetic material and is magnetically connected to the first pole of operation  122 . Further, a backgap portion is formed in operation  126  that is magnetically connected to the first pole distal the tapered first pole pedestal. A first insulation layer is formed in operation  128  between the tapered first pole pedestal and the backgap portion of operation  126 . 
   In operation  130 , the first insulation layer of operation  128 , and the first pole pedestal and backgap portion of operation  126  are chemically-mechanically polished. In a particular embodiment, the first insulation layer covers the tapered first pole pedestal and backgap portion in operation  128 , and the CMP operation of operation  130  exposes an upper surface of the tapered first pole pedestal and an upper surface of a back gap portion. In an alternative embodiment, the first insulation layer formation in operation  128  leaves the tapered first pole pedestal and the back gap portion exposed before the CMP of operation  130 . In either case, the CMP of operation  130  renders an upper surface of the tapered first pole pedestal, an upper surface of the back gap portion, and an upper surface of the first insulation layer each substantially planar, and substantially co-planar with each other. In operation  132 , a write gap layer is formed above the exposed tapered first pole pedestal and exposed backgap portion, and above the first insulation of operation  128 . The write gap layer can be formed of any suitable non-magnetic, electrically insulating material, such as alumina. 
   A tapered second pole pedestal formed of magnetic material is formed in operation  134 . A second insulation layer is formed in operation  136  above the write gap layer  132 . In operation  138 , the tapered second pole pedestal of operation  134  and the second insulation layer of operation  136  are chemically-mechanically polished. In a particular embodiment, the second insulation layer covers the tapered second pole pedestal in operation  136 . The operation  138  CMP then exposes the tapered second pole pedestal. In an alternative embodiment, the second insulation layers formed in operation  136  leaving the tapered second pole pedestal exposed without facilitation by the CMP of operation  138 . In either case, the CMP of operation  138  renders an upper surface of the tapered second pole pedestal and an upper surface of the second insulation layer substantially planar, and substantially co-planar with each other. 
   In operation  140 , a coil embedded in a third insulation layer is formed above the second insulation layer of operation  136 . Above the coil of operation  140 , a second pole formed of magnetic material is formed in operation  142 . The second pole of operation  142  is magnetically connected to the substantially planar upper surface of the tapered second pole pedestal  134  and to the backgap portion  126 . 
   As with method  100  of  FIG. 7 , the first pole can be provided above a substrate or above a read element, and can be incorporated as a second shield of a read element. Also, the formation of the tapered first pole pedestal and the tapered second pole pedestal can be substantially similar, including processes known to those skilled in the art, such as masking and plating followed by mask lift off. Further, the second pole can be formed in operation  142  with similar methods and of similar material as that for forming the first and second tapered pole pedestals and the first pole, for example permalloy. The first, second, and third insulation layers can be formed of any suitable non magnetic, electrically insulating material such as alumina, or cured photoresistive material. 
   The terms “first” and “second” as applied to the poles, pedestals, and insulation layers are used for convenience of explanation, and do not necessarily limit the order in which the elements are formed, nor the particular combination of elements. Also, only a single pedestal might be included, which may be magnetically connected to either pole, or two pedestals might be included, with only one being tapered. Therefore, for example, a write element of an exemplary embodiment of the present invention could include a first pole as well as a second pole that also operates as one of two shields of a read element. Further, a tapered pole pedestal may be magnetically connected to the second pole and separated from the first pole by a write gap. Additionally, a second, non-tapered pole pedestal (i.e., a second pole pedestal) may be connected to said first pole, and separated from the tapered pole pedestal (i.e., the first pole pedestal) by a write gap. 
   By defining the write element trackwidth by the trackwidth of a tapered pole pedestal, very small trackwidths can be defined. For example, trackwidths of less than 1 micron, including trackwidths of about 0.2 microns, can be achieved. In addition, these trackwidths can be tightly controlled, to a tolerance of σ TW  of no more than about 5 μins. With such closely controlled and small trackwidths, the write elements of an exemplary embodiment of the present invention can effectively operate in applications requiring recording densities on the order of about 40 Gbit/in 2 . Also, the tapered shape of the pole pedestal substantially eliminates the second pulse phenomenon, thereby improving the recording performance of the write element. 
   In summary, an exemplary embodiment of the present invention provides a method for providing a magnetoresistive write element that has more precisely defined and smaller trackwidth, and therefore exhibits increased write performance over previous write elements. The invention has been described herein in terms of exemplary embodiments. Other embodiments of the invention, including alternatives, modifications, permutations and equivalents of the embodiments described herein, will be apparent to those skilled in the art from consideration of the specification, study of the drawings, and practice of the invention. For example, the above described write element can be incorporated with a read element to provide a read/write head, or further incorporated with other components of a disk drive system. The embodiments and preferred features described above should be considered exemplary, with the invention being defined by the appended claims, which therefore include all such alternatives, modifications, permutations and equivalents as fall within the true spirit and scope of the present invention.