Patent Publication Number: US-6338939-B1

Title: Embedded dual coil fabrication process

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 09/178,377, filed on Oct. 23, 1998, now U.S. Pat. No. 6,191,918. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to read/write heads for reading and writing digital data to storage media such as magnetic disks. More particularly, the invention concerns a read/write head with a unique embedded planar dual coil structure, and a process for manufacturing such a head. 
     2. Description of the Related Art 
     In this modern information age, there is a tremendous volume of electronic data for people and computers to manage. The management requirements not only involve transmission, receipt, and processing of this information, but storage of the data as well. And, with more data to store, computer users are demanding extremely high capacity digital data storage devices. One of the most popular data storage devices is the magnetic disk drive system, also known as a “hard drive.” 
     In magnetic disk drives, one of the most critical components is the read/write head. Read/write head characteristics ultimately determine how densely, quickly, and accurately data can be written to magnetic disk media. As a result, engineers are continually developing better and better read/write heads. Two of the chief areas of focus in read/write head development are data storage density (“areal density”), and read/write speed. In this respect, one improvement in the signal storage ability of read/write heads has been the use of two write coils. This has been shown to significantly improve the strength and efficiency of the data storage. 
     FIG. 1 shows a partial cross-sectional view of an exemplary dual write coil read/write sensor  100 , with the slider&#39;s deposit end (“trailing”) being shown at  103 , and the air bearing surface shown  101 . The leading edge (not shown) resides in the direction  105 . The sensor  100  is built upon a slider  102 , beginning with an undercoat  104 . Upon the undercoat  104  lies a first shield  106 , known as “S 1 ,” followed by first and second gap layers  108 ,  110 . Between the gap layers  108 ,  110  lies a magneto resistive (“MR”) stripe  107 . Upon the gap layer  110  lies a combination shield/pole  112  known as “S 2 /P 1 .” The shield  106 , MR stripe  107 , and shield/pole  112  cooperatively form a magneto resistive read head  113  of the read/write sensor. 
     A write gap layer  113  is built upon the shield/pole  112 , followed by an organic insulating layer  114 . Upon the insulating layer  114  is based a first write coil  116 , which includes a conductive coil embedded in an organic insulating material that is applied to fill the spacing between coil turns and separate the first coil layer from a second coil layer to follow. The second write coil  118  is layered on top of the first write coil  116 , and similarly includes insulating material applied to fill the spacing between coil turns. A second pole  120 , known as “P 2 ,” lies atop the second write coil  118 . After fabricating the second write coil layer  118  and its insulation, a plating seed layer (not shown) is deposited, followed by a photo lithography process that defines the shape of the second pole  120 . The “track width” constitutes the width of the second pole  120  (in a direction perpendicular to the page depicting FIG. 1) at the air bearing surface  101 . Track width determines the track density on the disk where bits are written to and read from. The second pole  120  is protected by an overcoat layer  122 . The shield/pole  112 , write coils  116 / 118 , write gap  113 , insulation layer  114 , and second pole  120  provide the write head  123  aspect of the read/write sensor  100 . 
     One drawback of the sensor  100  is the severe topography created by the substantial height of the coil layers  116 ,  118  and insulation layer  114 . This topography is severe because it presents a significant curvature beneath the pole  120 , instead of a normally flat surface. In a two coil layer structure with organic insulation, the height of this structure can be as great as ten microns. This great height makes it extremely difficult to define the second pole  120 , especially when a narrow track width is required, for the following reasons. The track width corresponds to the dimension of the second pole  120  in a direction perpendicular to the view of FIG. 1 (i.e., into the page). When track width is extremely narrow, there is a high “aspect ratio,” defined as the ratio of the second pole&#39;s width (track width) to its length (from right to left in FIG.  1 ). Normally, when track width is larger than the second pole&#39;s length, no difficulty is presented for creating the pole  120  with known photo lithography processes. However, with the dual coil structure of FIG. 1, the second pole  120  exhibits a high aspect ratio, rendering photo lithography difficult or impossible. Moreover, this difficulty increases dramatically with more severe topographies, especially with today&#39;s track widths, which are frequently in the submicron range. In some cases, this difficulty may be so great that fabrication of the desired write head may be impossible. 
     Another drawback of the arrangement  100  is the amount of organic insulation present in the head. As mentioned above, organic insulation is present around the write coils  116 ,  118  as well as the insulating layer  114 . The organic insulating material is typically a polymeric material. During operation, the write head is heated from current passing the coils. Organic insulation has a lower thermal conductivity than dielectric materials in the head, such as silicon-oxygen and aluminum-oxygen based materials. This low thermal conductivity impedes heat dissipation, causing the temperature of the write head to increase. Increased operating temperatures have various undesirable effects, such as decreasing head life. Furthermore, due to the organic insulation&#39;s relatively high thermal expansion coefficient, the organic insulation responds to the heat by expanding more than the nearby layers of the head. This expansion may cause portions of the head to protrude from the normally flat air bearing surface  101 . With the head now enlarged by the protrusions, the head&#39;s effective flying height is smaller, and there is a greater danger of the head contacting the storage surface. Such contact may cause further heating of the head, or a disastrous head crash in extreme cases. To avoid head/disk contact, a higher flying height is necessary between the head and disk surface. However, with a higher flying height, signals stored by the write head are weaker, and require more surface area to safely store adjacent signals that are distinguishable from each other. Thus, the protrusion due to the presence of the organic insulation ultimately lowers the areal density of stored signals, diminishing the disk drive&#39;s storage capability. 
     In view of the foregoing, then, the structure and fabrication of known dual coil write heads present a number of unsolved problems. 
     SUMMARY OF THE INVENTION 
     Broadly, the present invention concerns an improved read/write head, including an embedded planar dual coil write structure. The head includes a shield layer, a shield/pole layer substantially parallel to the shield layer, and a pole layer substantially parallel to the shield and shield/pole layers. In one embodiment, one edge of the generally planar shield/pole layer reaches an air bearing surface of the head, and the opposite edge abuts a substantially coplanar planarization material. A circuitous channel spans the junction between the shield/pole and the planarization material twice, encircling a central “hub” (or “island”) of shield/pole and bordering planarization material. A write structure is located in this channel, called a “recess”, with the shield/pole and its portion of the embedded write structure covered by the pole layer. 
     The write structure includes first and second substantially coplanar multi-turn flat coils, where turns of the first write coil are interspersed with turns of the second write coil. Coil turns are substantially parallel to the shield/pole layer. The coils reside in the recess defined in the shield/pole layer and the planarization material and wind around the central hub. A dielectric material is present to separate the first coil from the second coil. 
     Accordingly, one aspect of the invention is an apparatus, such as a read/write head with an embedded planar coil write structure, or a disk drive system incorporating such a head. A different aspect is a method of fabricating the read/write head of the invention. 
     The invention affords its users with a number of distinct advantages. Unlike prior configurations, the invention provides a manageable topography for constructing a second pole layer in a dual coil read/write head. As a result, even with a dual coil construction, the invention may be used to construct read/write heads that define minuscule track widths of previously impossible dimension. Another advantage is that the invention&#39;s read/write head includes significantly less organic insulation material, since the two coils are integrated. This helps avoid undesirable heating and associated thermal expansion of the head. As a result, flying height can be lowered, increasing the areal density of stored signals, and proportionally decreasing the overall size of the storage media. The invention also provides a number of other advantages and benefits, which should be apparent from the following description of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial cross-sectional diagram of a known dual coil read/write head. 
     FIG. 2 is a perspective view diagram of a slider incorporating the read/write head of the invention. 
     FIG. 3 is a partial cross-sectional side view of the read/write head of the invention. 
     FIG. 3A is a cut-away top view of the read/write head of the invention with organic insulation, write gap, P 2 , and protective overlayer removed to feature the embedded planar dual coil structure of the invention. 
     FIG. 4 is a block diagram of a disk drive system utilizing the read/write head of the invention. 
     FIG. 5 is a flowchart of an operational sequence for fabricating an embedded planar dual write coil structure in accordance with the invention. 
     FIGS. 6A-6L are partial cross-sectional side views of a read/write head in various stages of fabrication according to the invention. 
     FIG. 7 is a diagram showing etch rates of NiFe, alumina, and photo resist as a function of milling angle. 
    
    
     DETAILED DESCRIPTION 
     The nature, objectives, and advantages of the invention will become more apparent to those skilled in the art after considering the following detailed description in connection with the accompanying drawings. As mentioned above, the invention concerns a read/write head with a unique embedded planar dual coil structure, and a process for manufacturing such a head. As described below, a different aspect of the invention is a disk drive system incorporating a read/write head with an embedded dual coil write structure. 
     HARDWARE COMPONENTS &amp; INTERCONNECTIONS 
     Slider 
     FIG. 2 depicts a read/write head  200  in perspective view to help explain the invention in context. The head  200  includes an air bearing surface (“ABS”)  202  which normally glides over a storage disk (not shown) separated by a thin cushion of air called an “air bearing” (not shown). In the illustrated example, the head  200  moves in a direction  205  relative to the storage medium. The ABS  202  is raised with respect to a surrounding surface  204  that is recessed by a process such as etching, ion milling, etc. 
     The head  200  has a leading edge  206  and a trailing edge  208 . Near the trailing edge  208  lies a read/write head  210 , which lies flush with the ABS  202  and contains circuit components that actually perform the read and write operations. These circuit components are deposited onto the trailing edge  208  of the head  200 , which may also be called the “deposit end.” As explained in greater detail below, the read/write head  210  includes a shield  220 , a shield/pole  222 , and a pole  224 , each too small to be separately visible in FIG.  2 . The shield  220  may also be called “S 1 ,” the shield/pole  222  may be referred to as “S 2 /P 1 ,” and the pole  224  may be referenced as “P 2 .” 
     Read/Write Head Structure 
     FIG. 3 shows a partial cross-sectional view of the read/write head  210 , which was generally described above with reference to FIG.  2 . Referring to FIGS. 2-3, the read/write head  210  is built upon the trailing edge  208  of the head  200 . More particularly, the read/write head  210  is built upon material of a slider  302 , which may also be referred to as a substrate. The substrate may comprise silicon, a semiconductor, or another material with similar properties. As a specific example, the substrate may be a combination of elements such as aluminum, oxygen, titanium, and carbon. Above the slider  302  lies an undercoat layer  304 , followed by the shield  220  (S 1 ). The shield  220  comprises a magnetic material such as a nickel-iron alloy, nickel-iron-cobalt alloy, Sendust, a cobalt-zirconium-niobium alloy, etc. Atop the shield  220  lies a first gap layer  306 , a second gap layer  310 , and an MR stripe  308  interposed between the gap layers  306 / 310  proximate to the ABS  202 . The gap layers  306 / 310  may comprise electrical insulators, for instance. 
     In the illustrated example, the gap  310  is covered by the shield/pole  222  (S 2 /P 1 ), and also by a planarization layer  312  that abuts the shield/pole  222  at a junction  395 . The shield/pole  222  and planarization layer  312  together form an intermediate layer  380  between the shield  220  and pole  224 . In the illustrated example, the planarization layer  312  comprises an electrical insulator such as alumina, another aluminum-oxygen combination, a silicon-oxygen combination, or another material with suitable properties such as electrical insulation, a similar expansion coefficient as the shield  222 , similar wear characteristics (e.g. lapping) as the shield  222 , etc. The shield  222  comprises a magnetic material such as a nickel-iron alloy, nickel-iron-cobalt alloy, Sendust, cobalt-zirconium-niobium alloy, etc. In the alternative embodiment, the planarization layer  312  may comprise a conductive non-magnetic material. Although using an electrical insulator or conductive non-magnetic material as the planarization layer  312  offers the advantage of low inductance, the planarization layer  312  may comprise a magnetic material and may even be indistinguishable from the shield/pole  312 ; in this embodiment, the intermediate layer  380  and the shield/pole (S 2 /P 1 ) are the same, and the shield/pole occupies both regions  222  and  312 . For explanatory purposes, the present discussion illustrates the embodiment where the shield/pole  222  and planarization layer  312  are separate materials that meet at the junction  395 . 
     The intermediate layer  380  exhibits a contiguous recess  314  defined in the shield/pole  222  and the layer  312  and spanning the junction between these parts. The recess  314  has the shape of a circuitous channel that spans the junction  395  twice, encircling a central “hub”  390  of shield/pole and adjacent planarization material. The recess  314  is “circuitous” in that it defines a continuous path, with no end or beginning as it travels around the central hub  390 . The recess  314  is a contiguous channel traveling around the hub  390 , but due to the cross-sectioned view of FIG. 3 appears as two separate recessed areas  314   a - 314   b.  As one example, the recess  314  may exhibit a ring (“annular”) shape, with the hub  390  as its center. The recess  314  may, however, exhibit more elliptical, rectangular, or other features, depending upon the shape of the embedded planar dual coil write structure  315  to reside therein. 
     More specifically, the planar dual coil write structure  315  includes an insulating layer  316 , comprising alumina or another material with similar properties of electrical insulation. Atop the layer  316  reside a pair of write coils, made of a conductive material such as copper or another material with similar properties. The overall structure of each write coil is generally flat, where each coil starts from a central point and proceeds outward. As one example, the coils may be shaped spirally, like a burner coil of an electric stove. Alternatively, more elliptical, rectangular, or other shapes may be used. As both coils start and proceed outward together, the turns of one coil are interspersed with those of the other. One coil includes turns  320 , whereas the other coil includes alternating turns  322  interspersed with the turns  320 . The individual turns are tapered. In the case of the turns  320 , for instance, they are tapered to provide a wider dimension toward the substrate  302 . The turns  322  have an opposite taper, providing a smaller dimension toward the substrate  302 . In the illustrated example, each tapered coil turn exhibits a generally trapezoidal cross section. The turns of one coil are electrically separated from the other coil&#39;s turns by a layer  318 , which comprises an insulating material such as a dielectric substance. FIG. 3A shows the dual coil structure from a top view, with all layers (i.e.,  324 ,  326 ,  224 ,  350 ) overlying the intermediate layer  380  and coils  320 / 322  removed, to more thoroughly illustrate the coil structure. 
     Over the shield/pole  222 , dual coil write structure  315 , and planarization layer  312  lies an insulating layer  324 , which comprises an insulating material such as organic polymer, dielectric, an aluminum-oxygen combination, a silicon-oxygen combination, etc. Above the layer  324  is a write gap layer  326 , comprising a non-magnetic, conductive or non-conductive material such as an aluminum-oxygen combination. The last magnetic component of the read/write head  210  is the pole  224 , which overlies the write gap layer  326 . The pole  224  comprises a magnetic material of similar composition as the shield  220  and shield/pole  222 . The pole  224  is covered by a protective overlayer  350 , made of alumina or another material seeming to encapsulate the head  200  and provide sufficient chemical and mechanical protection. A protective over layer  309  may also be applied at the air bearing surface, to guard various layers of the read/write head that would otherwise be exposed, such as layers  304 ,  220 ,  306 ,  308 ,  310 ,  222 ,  326 , and  224 . The layer  309  may comprise carbon or another layer providing sufficient chemical and mechanical protection to the read/write head  210 . 
     Disk Drive System 
     FIG. 4 shows a different aspect of the invention, comprising a disk drive system  400  incorporating a read/write head with an embedded planar dual coil write structure. The disk drive system  400  includes at least one rotatable magnetic disk  412  supported on a spindle  414  and rotated by a disk drive motor  418 . The magnetic recording media on each disk is in the form of an annual pattern of concentric data tracks (not shown) on the disk  412 . 
     At least one slider  413  is positioned near the disk  412 , each slider  413  supporting one or more magnetic read/write heads  421 , where the head  421  incorporates the read/write head of the present invention. As the disks rotate, the slider  413  is moved radially in and out over the disk surface  422  so that the heads  421  may access different portions of the disk where desired data is recorded. 
     Each slider  413  is attached to an actuator arm  419  by means of a suspension  415 . The suspension  415  provides a slight spring force that biases the slider  413  against the disk surface  422 . Each actuator arm  419  is attached to an actuator mechanism  427 . The actuator mechanism  419 , for example, may be a voice coil motor (“VCM”) comprising a coil movable within a fixed magnetic field, where the direction and speed of the coil movements are controlled by the motor current signals supplied by the controller  429 . 
     During operation of the disk drive system  400 , the rotation of the disk  412  generates an air bearing between the slider  413  and the disk surface  422 , which exerts an upward force or “lift” on the slider. The surface of the slider  413  that includes the head  421  and faces the surface  422  is referred to as an air bearing surface (“ABS”). The air bearing counterbalances the slight spring force of the suspension  415  and supports the slider  413  off and slightly above the disk surface by a small, substantially constant spacing during normal operation. 
     In operation, the various components of the disk storage system are controlled by control signals generated by a control unit  429 . These control signals include, for example, access control signals and internal clock signals. As an example, the control unit  429  may include various logic circuits, storage, and a microprocessor. The control unit  429  generates control signals to control various system operations such as drive motor control signals on line  423  and head position and seek control signals on a line  428 . The control signals on the line  428  provide the desired current profiles to optimally move and position the slider  413  to the desired data track on the disk  412 . Read and write signals are communicated to and from read/write heads  421  by means of a recording channel  425 . 
     The above description of the magnetic disk storage system and accompanying illustration of FIG. 4 are for representation purposes only. Ordinarily skilled artisans (having the benefit of this disclosure) should recognize various additions or other changes that may be made to the system  400  without departing from the invention. Moreover, disk storage systems may contain a large number of disks and actuators, and each actuator may support a number of sliders. 
     Fabrication Process 
     In addition to the various hardware embodiments described above, a different aspect of the invention concerns a process for fabricating a read/write head with a unique embedded planar dual coil structure. 
     Introduction 
     FIG. 5 shows a sequence  500  to illustrate one example of the process aspect of the present invention. The sequence  500  describes the construction of a read/write head incorporating the embedded planar dual write coil structure of the invention. For ease of explanation, but without any limitation intended thereby, the example of FIG. 5 is described in the context of the head shown in FIGS. 3-3A, and described above. 
     Building Initial Structure 
     After the process  500  is initiated in step  502 , the read/write head is built until the shield/pole  222  is completed, as shown by step  504 . This involves fabrication of the slider  302 , overlayer  304 , shield  220 , gap layers  306 / 310 , and MR stripe  308 . As an example, these operations may be performed using techniques well known to ordinarily skilled artisans in this art. Upon the gap layer  310 , the shield/pole  222  and planarization layer  312  are constructed. These components have substantially the same thickness, and abut each other at a common junction  395 . 
     Defining Recess 
     Having completed the read/write head up to the level of the intermediate layer  380 , step  506  is then performed to define the  314  recess spanning the shield/pole  222  and the adjacent planarization layer  312  to accommodate the write coils. Creation of the recess  314  begins with the read/write head in the condition shown in FIG.  6 A. At this point, the shield/pole  602  and adjacent layer  604  do not yet define any recesses. These layers meet at a junction  395 , and provide a continuous, substantially flat surface  605 . The layers  602  and  604  have a common lower surface  690  abutting the gap layer  310 , which is not shown in FIGS. 6A-6L for ease of illustration. 
     The recess  314  (as shown by areas  314   a - 314   b ) is defined using a photo lithography process, which begins in FIG.  6 B. Namely, photo resist masks  606   a - 606   b  are applied to define an opening  607  (areas  607   a - 607   b ) defining the desired location of the recess  314  (areas  314   a - 314   b ). The location of the mask  606   b  determines the position of the hub  390  (FIG.  3 ). Next, an ion milling process is applied to erode the shield/pole  602  and the layer  604  at substantially the same rate. In this present example, where the shield/pole  602  is made of a nickel-iron alloy and the layer  604  is made of alumina, a special technique is used to erode these materials at the same rate. Namely, this technique involves performing ion milling with the wafer tilted at about fifty to sixty degrees (“milling angle”) using ion beam voltage of about 650 volts. The inventors have discovered that this technique mills the shield/pole  604  and layer  604  at about the same rate. FIG. 7 shows the milling rate of nickel-iron (NiFe), alumina, and photo resist as a function of milling angle at 650 V beam voltage. The milling rates of nickel-iron and alumina are essentially equal at milling angles of about fifty to sixty degrees. 
     After the shield/pole  602  and overlayer  604  are milled sufficiently to the desired depth, and the photo resist masks  606   a - 606   b  removed, the read/write head appears as shown in FIG.  6 C. Namely, recessed areas  314   a - 314   b  are now provided in the opening  607  left by the masks  606   a - 606   b.  Removal of the photo resist masks  606   a - 606   b  may be achieved by applying a solvent, or another known technique. The milled shield/pole  308  and milled planarization layer  610  are shown in FIG.  6 C. 
     Constructing Write Structure—Coating Recess with Insulation 
     With construction of the read/write head advanced to the state shown in FIG. 6C, construction of the write structure occurs in step  508 . As shown below, the write structure includes a pair of substantially planar coils, and these coils are embedded in the recessed areas  314   a - 314   b  created in the shield/pole  608  and planarization layer  610 . In step  510 , the recessed areas  314   a - 314   b  are coated with a layer  316  of alumina or another insulating material of similar properties. As an example, the layer  316  may have a thickness of about 2000 Angstroms. This is performed to electrically insulate the shield/pole  608  from the write coils, and may be accomplished using a suitable technique such as vacuum deposition. More particularly, step  510  may employ sputtering deposition. The completed insulation layer  316  is shown in FIG.  6 D. 
     Constructing Write Structure—First Coil 
     After step  510 , the first coil is applied in step  511 , this step involving a number of sub-steps. First, as shown in FIG. 6E, a conductive seed layer  614  is applied by an appropriate technique, such as sputtering deposition. As an example, the seed layer  614  may comprise a chromium/copper layer (CrCu) of about 800 Angstroms. The seed layer  614  provides a surface conducive to the addition of conductive coil material, as discussed below. 
     Next, a “cast” is made in the proper shape to create coils of the first write coil. A completed cast  616  is shown in FIG. 6F, and may be constructed by a suitable photo lithography process. For example, a resist material, such as a photosensitive polymer, may be applied using a spin coat technique. Then, a mask is applied for exposure and the unwanted resist material is dissolved using a developing chemical. This forms a cast  616 , which is made of the resist material. The cast  616  includes a number of openings  618 , which define the shape of the first write coil, as discussed below. 
     In the illustrated embodiment, the openings  618  are “tapered,” being wider at the bottom and narrower at the top to define a shape of trapezoidal cross-section. This is useful, as discussed below, because the resultant first write coil will provide a cast for creating a second write coil of complementary shape. This tapered shape is achieved by using a negative tone resist. 
     With the cast  616  defined, the coil material is applied to the openings  618 . As an example, this material may be copper, which is applied by electroplating. After applying the coil material, the resist cast  616  is stripped using an organic solvent such as acetone or N-methylpyrrolidone or another dissolving chemical; also the seed layer  614  is removed using a dry etch technique such as ion milling. This completes the first coil and step  511 . As shown in FIG. 6G, the coil includes multiple turns  320 , the shape of which has been defined by the now-absent resist openings  618 . 
     Constructing Write Structure—Encapsulating 
     After the first write coil is constructed in step  511 , the dielectric layer  318  is applied over the first write coil in step  512 . This encapsulates the turns, insulating them from the second write coil, to be applied next. Step  512  may be performed by applying a dielectric material by a suitable vacuum deposition technique, such as chemical vapor deposition, sputtering, plasma deposition, or enhanced chemical vapor deposition. As a more specific example, the dielectric layer  318  may comprise 5000 Angstroms of chemical vapor deposition (“CVD”) or plasma enhanced chemical vapor deposition (“PECVD”). The tapered shape of the write coil  320  improves the coverage of the dielectric layer  318  over the coil turns. 
     FIG. 6H depicts the read/write head with encapsulated write coils. The surface of the dielectric layer  318  defines a number of recesses  624 , shaped to provide a cast for construction of the second write coil. 
     Constructing Write Structure—Second Coil 
     After the insulation is applied in step  512 , construction of the second write coil begins. Referring to FIG. 6I, a seed layer (not shown) is first applied to the dielectric layer  318  by an appropriate technique, such as sputtering deposition. As an example, the seed layer may comprise a chromium/copper layer (CrCu). The seed layer provides a surface conducive to the addition of conductive coil material, as discussed below. 
     Next, a suitable photo lithography process is performed to construct a resist mask  629  covering the read/write head, except for the recessed areas  314   a - 314   b.  The resist mask  629  may additionally cover a small portion of the outer ends of the recessed areas  314   a - 314   b  (as shown), in order to avoid the deposition of coil material in those areas. The resist mask  629  is constructed by applying a resist material (not shown), such as a photosensitive polymer, using a spin coat technique. Then, another mask (not shown) is applied and the exposed resist material is dissolved using a developing chemical. This forms the resist mask  629 , which provides openings  625   a - 625   b.    
     With the resist mask  629  in place as shown in FIG. 6I, a coil material is applied. Application of the coil material is limited to area left by the openings  625   a - 625   b.  As an example, the coil material may be copper, which is applied by electroplating. After applying the coil material, the resist mask  629  is stripped using an organic solvent such as acetone or N-methylpyrrolidone or another dissolving chemical; also, the seed layer is removed using a dry etch technique such as ion milling. This completes step  513 , leaving the read/write head in the condition shown by FIG.  6 J. Although the material of the second coil is in place, some finishing work still remains, as explained below. 
     Constructing Write Structure—Finishing 
     After step  513 , a finishing step  514  is performed. First, the read/write head is processed with chemical-mechanical polishing to wear away the excess copper material  626  protruding beyond the recesses  614   a - 614   b.  More particularly, polishing may be performed using a slurry of quartz particles suspended in persulfate ammonium potassium aqueous solution, with the persulfate concentration at about 3%. After polishing, the seed layer is removed by a suitable technique, with one example being a dry etch technique such as ion milling. With the seed layer gone, material of the dielectric layer  318  protruding beyond the recessed areas  314   a - 314   b  is removed by a process such as a wet etch technique. 
     The result of the finishing step  514  is the read/write head as shown in FIG.  6 K. At this point in the fabrication process, the first coil  320  and second coil  322  are in place. Turns of the first coil  320  alternate with turns of the second coil  322 . The turns of each coil are insulated from the other coil by the insulating layer  318 . All coil turns exhibit a tapered shape, where turns  320  of the first coil are wider toward the underlying shield/pole  608 , and turns  322  of the second coil are narrower toward the shield/pole  608 . Both write coils are completely embedded in the shield/pole  608  and the planarization layer  610 , with these structures cooperatively providing a flat surface  670  for building the pole  224 , as discussed below. 
     Completing the Read/Write Head 
     After step  514 , the write structure is complete, ending step  508 . Next, step  516  is performed to complete the read/write head. First, the insulating layer  324  is applied over the recess  314  containing the write coils as shown in FIG.  6 L. Application of the insulation layer  324  may be achieved using photo lithography, the details of which have been explained above. The insulating layer  324  comprises an organic material, such as a polymer. After placing the insulation layer  324 , it may be cured by baking. 
     Upon the insulating layer  324  is placed a write gap  326 , as shown in FIG.  6 L. The write gap may be layered using vacuum deposition, for example. Placement of the write gap  326 , and the ensuing pole  224  and protective overcoat  350  (not shown in FIG. 6L) may be achieved by well known techniques. Known methods may also be used to connect the write coils  320 ,  322  to appropriate conductive leads. 
     Other Embodiments 
     While the foregoing disclosure shows a number of illustrative embodiments of the invention, it will be apparent to those skilled in the art that various changes and modifications can be made herein without departing from the scope of the invention as defined by the appended claims. Furthermore, although elements of the invention may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.