Abstract:
A trailing pole-tip for an electromagnetic transducer is formed as a layer oriented substantially perpendicular to other layers of the transducer, allowing the pole-tip to be made much thinner than conventional pole-tips. The novel pole-tip is formed on an edge or sidewall of a base layer instead of being formed on top of an existing layer. Potential errors in pole-tip thickness are much less than standard error tolerances for conventional pole-tip thickness. Having a greatly reduced pole-tip width significantly reduces the track width so that many more tracks can fit on a media surface, providing a large increase in areal density.

Description:
BACKGROUND 
     A key measure of the performance of an electromagnetic information storage system is the areal density. The areal density is the number of data bits that can be stored and retrieved in a given area. Areal density can be computed as the product of linear density (the number of magnetic flux reversals or bits per unit distance along a data track) multiplied by the track density (the number of data tracks per unit distance). As with many other measures of electronic performance, areal densities of various information storage systems have increased greatly in recent years. For example, commercially available hard disk drive systems have enjoyed a roughly tenfold increase in areal density over the last few years, from about 500 Mbit/in 2  to about 5 Gbit/in 2 . 
     Various means for increasing areal density are known. For instance, with magnetic information storage systems it is known that storage density and signal resolution can be increased by reducing the separation between a transducer and associated media. For many years, devices incorporating flexible media, such as floppy disk or tape drives, have employed a head in contact with the flexible media during operation in order to reduce the head-media spacing. Recently, hard disk drives have been designed which can operate with high-speed contact between the hard disk surface and the head. 
     Another means for increasing signal resolution that has become increasingly common is the use of magnetoresistive (MR) or other sensors for a head. MR elements may be used along with inductive writing elements, or may be separately employed as sensors. MR sensors may offer greater sensitivity than inductive transducers but may be more prone to damage from high-speed contact with a hard disk surface, and may also suffer from corrosion, so that conventional MR sensors are protected by a hard overcoat. 
     Recent development of information storage systems having heads disposed within a microinch (μin) of a rapidly spinning rigid disk while employing advanced MR sensors such as spin-valve sensors have provided much of the improvement in areal density mentioned above. Further increases in linear density have been hampered by demagnetizing forces from adjacent bits, which grow stronger as the bits are packed closer together, typically manifested as nonlinear transition shifts (NLTS) of longitudinal media. On the other hand, further increases in track density have been limited by constraints as to how small transducer pole-tips can be made, since the pole-tips record magnetic patterns on the media and therefore define the width of each track. 
       FIG. 1  (Prior Art) depicts a portion of a conventional thin film head  50  as seen from a media on which the head writes and reads. The head contains a transducer formed in a series of layers on a substrate  51 , the transducer including a MR sensor  52  sandwiched between a pair of magnetically permeable shield layers  54  and  55 . Layer  55  also serves as a first pole-tip of a magnetically permeable yoke that encircles a conductive coil, not shown, the first pole-tip  55  being separated from a second pole-tip  58  by a recording gap  60 . In this example of a merged MR and inductive head, reading of signals is performed by the MR sensor  52 , while writing of patterns on the media is performed by magnetic flux spreading out from the gap  60  while travelling between the pole-tips  55  and  58 . A width W 0  of the trailing pole-tip  58  thus sets a minimum width of a data track recorded on the medium. Conventional pole-tips  55  and  58  are formed by sputtering a seed layer followed by patterning a photoresist mask for electroplating, to form a layer that may be a few microns thick for carrying sufficient magnetic flux to provide adequate recording strength to the media. After electroplating through the thick mask, the mask is chemically removed and the seed layer is removed by ion beam milling, which can also be used to thin the pole-tip. 
     Control of the ion milling for thinning pole-tips becomes difficult for widths W 0  that are less than 0.5 μm, and errors in mask definition increase with mask thickness, limiting a length-to-width aspect ratio of conventional pole-tips to less than six. Instead of ion milling at the wafer level, trimming of a pole-tip with a focused ion beam impinging upon the air-bearing surface has been proposed. Unfortunately, this leaves a cavity in that surface around the pole-tip, and tends to round the corners of the pole-tip adjacent the cavity. Moreover, trimming with an individual beam for each pole-tip is not competitive with mass production of pole-tips at the wafer level. 
     SUMMARY 
     In accordance with the present invention, a trailing pole-tip for an electromagnetic transducer is formed as a layer oriented substantially perpendicular to most if not all other layers of the transducer, allowing the pole-tip to be made much thinner than conventional pole-tips. The novel pole-tip may be formed on an edge or sidewall of a base layer instead of being formed on top of an existing layer. An advantage of such sidewall formation is that errors in pole-tip thickness can be much less than standard error tolerances for conventional pole-tip thickness. Another advantage is that such a pole-tip can be formed to a narrow width while the transducer is being mass produced along with perhaps thousands of other transducers on a wafer, instead of being formed individually on a media-facing surface after separation from other transducers. Having a greatly reduced pole-tip width can significantly reduce the track width so that many more tracks can fit on a media surface, providing large increases in areal density. For conciseness this summary merely points out a few salient features in accordance with the invention, and does not provide any limits to the invention, which is defined below in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  (Prior Art) is a cutaway view of a media-facing side of a head focusing on a conventional transducer. 
         FIG. 2  is a cutaway view of a media-facing side of a head in accordance with the present invention focusing on a transducer having a narrow pole-tip. 
         FIG. 3  is a cutaway cross-sectional view of the head of  FIG. 2 , focusing on the transducer portion of the head. 
         FIG. 4  depicts some steps in the formation of the narrow trailing pole-tip that was shown in  FIG. 2  and  FIG. 3 , viewed along a cross-section located close to what will become the media-facing surface. 
         FIG. 5  depicts some steps in the formation of a laminated narrow trailing pole-tip that was shown in  FIG. 2  and  FIG. 3 , viewed along a cross-section located close to what will become the media-facing surface. 
         FIG. 6  is a cutaway cross-sectional view of a step in the formation of the head of  FIG. 2  and  FIG. 3 , depicting anisotropic removal of a layer that was deposited in  FIG. 4 . 
         FIG. 7  is a cutaway cross-sectional view of a later step in the formation of the head of  FIG. 2  and  FIG. 3 , depicting selective removal of a base layer to leave a naked magnetic layer. 
         FIG. 8  is a cutaway cross-sectional view of an alternative embodiment of a later step in the formation of the head of  FIG. 2  and  FIG. 3 , in which base layer has been formed of a material that remains intact adjacent the magnetic layer. 
         FIG. 9  is a cutaway cross-sectional view of a later step in the formation of the head of  FIG. 2  and  FIG. 3 , depicting encasing the magnetic layer in an amagnetic layer, and planarizing those layers. 
         FIG. 10  is a cutaway cross-sectional view of another embodiment of a head in which a narrow trailing pole-tip is formed subsequent to formation of a coil layer but prior to formation of a second yoke layer. 
         FIG. 11 , is a cutaway perspective view of a deposition step in creating the trailing pole-tip of  FIG. 10 . 
         FIG. 12  is a cutaway view of a media-facing side of the head of  FIG. 10 , focusing on the transducer. 
         FIG. 13  is a cutaway cross-sectional view of an embodiment of a head like that of  FIG. 10  but having a trailing pole-tip formed subsequent to formation of a second yoke layer. 
         FIG. 14  is a cutaway cross-sectional view of an embodiment of a head like that of  FIG. 13  but having a narrow trailing pole-tip that is formed prior to formation of a coil layer. 
         FIG. 15  is a cutaway perspective view of a base that serves as a template for creating the narrow, magnetically permeable trailing pole-tip. 
         FIG. 16  is a cutaway perspective view of the base of  FIG. 15  after an anisotropic removal process that leaves substantially vertical magnetic layers. 
         FIG. 17  is a schematic view of the transducer of  FIG. 14  from the trailing end, showing the coils and the second yoke, which tapers to adjoin the narrow trailing pole-tip. 
         FIG. 18  is a cutaway cross-sectional view of an embodiment of a head like that of  FIG. 14  but having a sloping side of a second yoke adjoining the pole-tip. 
         FIG. 19  is a cutaway cross-sectional view of an embodiment of a head like that of  FIG. 18  but having a level side of a second yoke adjoining the pole-tip distal to a write gap. 
         FIG. 20  is a cutaway cross-sectional view of an embodiment of a head like that of  FIG. 19  but having a flat second yoke adjoining the pole-tip distal to a write gap. 
         FIG. 21  is a cutaway cross-sectional view of an embodiment of a head like that of  FIG. 20  but having a relieved media-facing surface with pole-tips that project slightly compared to the yokes and MR sensor. 
         FIG. 22  is a cutaway cross-sectional view of the head of  FIG. 20  interacting with a media such as a rigid magnetic disk. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 2  is a cutaway view of a media-facing side of a head  100  in accordance with the present invention focusing on a transducer  102  having a narrow trailing pole-tip  105 . The pole-tip may have a width (W 1 ) that is 0.3 μm or less and a length (L 1 ) that is about 1 μm–2 μm, although either the width or length of the pole-tip can be varied by a factor of two or more. In general, a length-to-width (L 1 /W 1 ) aspect ratio for pole-tip  105  may exceed six and may approach infinity. For near-term products, length-to-width aspect ratios for pole-tip  105  may be in a range between about six and one-hundred. As described in detail below, the pole-tip  105  has been deposited as a layer on a substantially vertical sidewall, and so the width W 1  of the pole-tip is essentially the thickness of the layer. Such a pole-tip layer  105  can be made as thin as a few atoms in thickness, so that W 1  is less than 20 Å, although such an extremely narrow pole-tip is not currently necessary. The pole-tip may be made of high magnetic saturation (high B s ) materials, including iron films or laminates, primarily iron NiFe (e.g., Ni 45 Fe 55 ), Sendust (AlSiFe), or other known high B s  compounds. Cobalt-based alloys, such as CoZrNb, CoZrNb and CoZrRe, nitrogen doped iron films, such as compounds containing FeNX, where X can be Rh, Ta or Al, or compounds containing FeCo also may be used to form a high B s  pole-tip. Forming the pole-tip  105  of high B s  materials can avoid magnetic saturation despite the pole-tip having a much smaller cross-sectional area than most of the remainder of the magnetic yoke, not shown in this figure. The pole-tip  105  can also be laminated to provide for extremely high frequency operation without deleterious eddy currents. 
     The transducer  102  is formed in a series of layers on a substrate  107 , beginning with a first magnetically permeable shield layer  110 . For the situation in which the shield is made of Permalloy, the shield may have a thickness of about 2 μm and a width that is several times larger than its thickness. A first amagnetic (non-ferromagnetic), electrically insulating read gap layer is formed on the first shield  110  to separate the first shield from a MR sensor  112 . A second amagnetic, electrically insulating read gap layer is formed on the MR sensor  112  to separate the MR sensor from a second shield  115 . The read gap layers may have a thickness in a range between about 50 Å and 400 Å, and may be formed of a variety of materials including Alumina, DLC, SiC and SiO 2 . Second shield  115  also serves as a first pole-tip of a magnetically permeable yoke that encircles a conductive coil, not shown in this figure, the first pole-tip  115  being separated from the trailing pole-tip  105  by an amagnetic, electrically insulating recording gap  118 , which may have a thickness on the order of 200 nm. The trailing pole-tip  105  is encased with an amagnetic, electrically insulating layer defining a trailing end  138  of head  100 . In this embodiment of a merged MR and inductive head, reading of signals is performed by the MR sensor  112 , while writing of patterns on the media is performed by magnetic flux spreading out from the gap  118  while travelling between the pole-tips  105  and  115 . The width W 1  of the trailing pole-tip  105  corresponds to a width of a data track recorded on the medium, and may be more or less than the gap  118  between the pole-tips  105  and  115 . Although difficult to depict in this figure, the MR sensor  112  may have a width that is less than W 1 , and a thickness that is even less. 
       FIG. 3  is a cutaway cross-sectional view of the head  100  of  FIG. 2 , focusing on the transducer  102  portion of the head. A protective overcoat  106  made of a form of diamond-like carbon (DLC), such as tetrahedral amorphous carbon (ta-C), or silicon carbide (SiC), or other known materials may be disposed on a media facing surface  108  of the head and evident in  FIG. 3 , but is substantially transparent and so not shown in  FIG. 2 . The head  100  is formed on a wafer substrate  107 , that may be made of alumina (Al 2 O 3 ), alumina titanium carbide (Al 2 O 3 -TiC), silicon (Si), silicon dioxide (SiO 2 ), silicon carbide (SiC) or other known materials, the head being mass-produced along with hundreds or thousands of other heads. In an alternative embodiment, such a head may be formed on a magnetically permeable substrate, such as ferrite, which essentially becomes a first yoke layer. In this embodiment a leading and trailing pole-tip may be formed of high B s  material, and may be formed prior to an optional sensor. It is also possible to form the head on a substrate that is later removed. 
     After polishing and preparing a surface of the wafer substrate  107 , the first magnetically permeable layer  110  is formed of a material such as Permalloy (Ni 80 Fe 20 ), which will function as a magnetic shield. The first shield layer  110  may be formed by first sputtering a seed layer of Permalloy, then masking an area to leave an aperture for the shield to be grown by electroplating, then removing the mask and finally removing the sputtered seed layer not covered by the electroplated layer, as is conventional. A first read gap layer of an amagnetic, electrically insulating material such as Alumina, SiO 2  or DLC is then formed, on top of which the magnetoresistive (MR) sensor  112  is formed. The MR sensor  112  may be an anisotropic magnetoresistive (AMR) sensor, spin valve (SV) sensor, giant magnetoresistive (GMR) sensor, or other known sensors, the details of which are known in the art and omitted here for conciseness. One should note, however, that the MR sensor may be composed of a strata of layers having thicknesses ranging between about 4 Å and 100 Å, so that the MR sensor formed by the strata has a thickness less than 500 Å. For clarity, the MR sensor  112  in  FIG. 2  is depicted with a similar width as the width W 1  of the narrow trailing pole-tip, which may for example be 0.2 μm (2000 Å) or less, but the MR sensor may alternatively have a width that is less than or greater than that of the pole-tip  105 . Even for the case in which the MR sensor is trimmed to have a track width of 0.1 μm (1000 Å) or less, that width may still be substantially larger than the thickness of the MR sensor which, as mentioned above, may be less than 500 Å thick. A back gap and a second read gap of electrically insulating, amagnetic materials such as alumina, silicon dioxide or diamond-like carbon are also formed, which combine with the first read gap to form a layer  114  of electrically insulating, amagnetic material encasing MR sensor  112 . The first yoke layer  115  of magnetically permeable material such as Permalloy is then formed for transducer  102 , layer  115  also serving as a shield for the MR sensor  112  in this embodiment of a merged head. Note that other types of transducers may employ a narrow pole-tip according to the present invention, including piggyback heads, planar heads, heads removed from a substrate, heads having an integrated slider and suspension, heads having an optical sensor, heads with an MR sensor formed after the trailing pole-tip, and inductive heads without an additional sensor. Various types and processes of recording heads are described in Chapter 6 of the 2 nd  Edition of Magnetic Recording Technology, by C. Denis Mee and Eric D. Daniel, pages 6.1–6.102, incorporated herein by reference. 
     After the above-described conventional steps for making a merged head, the novel pole-tip  105  may be formed either before or after formation of an electrically conductive coil  120  for the transducer  102 . An advantage of the present invention is that a narrow pole-tip can be formed somewhat independently of a magnetically permeable yoke that substantially encircles an electrically conductive coil. Note also that describing a magnetically permeable yoke as substantially encircling an electrically conductive coil is meant to represent an inductive transducer, for which the coil may have a single turn or many and which may have a majority of its length not encircled by the yoke. For the case in which the pole-tip  105  is formed after formation of the coil, the pole-tip may be formed prior or subsequent to formation of a second yoke layer for the transducer. 
       FIG. 3  for example shows an embodiment in which the pole-tip  105  was formed subsequent to the coil  120  but prior to a second yoke layer  130  of magnetically permeable material such as Permalloy. In this case, an amagnetic, electrically insulating layer  113  is first formed that will provide the write gap, and which may provide a surface on top of which the conductive coil  120  is created. The coil may be formed by electroplating copper (Cu), gold (Au) or other conductive materials on a conductive seed layer through a mask that is then removed, after which the seed layer is removed. The coil  120  may then be surrounded by amagnetic, electrically insulating material such as Alumina, which can then be polished to essentially form layer  117  shown in  FIG. 3 . Layer  117  may then be masked and etched to define edges  122  and  123 , and the narrow pole-tip  105  can then be formed adjacent edge  122 . 
       FIG. 4  depicts some steps in the formation of the narrow trailing pole-tip  105  that was shown in  FIG. 2  and  FIG. 3 , viewed at a cross-section located close to what will become the media-facing surface. In this view, a layer  119  of amagnetic, electrically insulating material which surrounds yoke layer  115  is apparent, with layers  115  and  119  polished to form a smooth surface for gap layer  113 . A base layer  140  is formed on the insulating layer  113 , the base layer having a substantially vertical sidewall  142  disposed adjacent the yoke layer  115 . The base layer  140  for example may be a photoresist layer that has been developed to create sidewall  142 . Alternatively, the base layer  140  may be a ceramic layer or other hard, amagnetic, electrically insulating layer, such as Alumina, SiO 2  or Si 3 N 4 , which has been etched, milled or ablated to create sidewall  142 . 
     In  FIG. 4  a layer  144  of magnetically permeable material which will form the narrow pole-tip is then grown on the base layer  140 , sidewall  142  and the exposed portion of insulating layer  113 . The magnetically permeable material layer  144  may be formed in an evacuated chamber from gas, plasma or beams of ions, for example by chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD) with or without a collimator, ion beam deposition (IBD) or sputtering (RF or DC), which allows the layer  144  to be as thin as a few nanometers or less in thickness. In general, these different methods of forming the layer  144  result in a structure that is defined as vacuum-deposited. Layer  144  may be formed in the presence of a magnetic field, either during deposition or in a post deposition anneal, that helps to provide an easy axis of magnetization to the magnetic material, for example along the width W 1  or length L 1  direction of pole-tip  105 , shown in  FIG. 2 . Layer  144  may be formed may be formed of Permalloy or materials having a higher B s  than Permalloy. 
     Sputtering and other vacuum-deposition techniques may provide different material characteristics to the pole-tip than conventional formation by electroplating in a liquid solution. For example, the sputtered layer  144  may be denser than a similar electroplated layer, and is free of residual impurities, such as chlorine, sulfur and carbon-based molecules that may otherwise be left from an electroplating solution. These impurities can promote corrosion of the head and may also degrade magnetic performance characteristics of conventional pole-tips, for example by reducing permeability and B s . Eddy currents can also be reduced with vacuum-deposited pole-tip materials, allowing higher frequency operation. And although Permalloy is easy to electroplate, some materials having a higher B s  than Permalloy may be difficult to form by electroplating, limiting the magnetic performance of conventional pole-tips. In particular, compounds containing refractory metals, such as elements found in columns IVB–VIB of the periodic table (e.g., Zr, Ta and Cr), may be difficult to electroplate but may be formed by sputtering in accordance with the present invention. 
     Deposition of the magnetically permeable material may occur at an angle from normal to the wafer surface, as shown by arrows  146 , covering sidewall  142 . The deposition angle may range between zero and about eighty degrees, and may be static or rotating, depending in part whether upon whether the transducers laid out on the wafer surface have identical adjacent structures or mirror-image layouts. For the situation in which the magnetically permeable material is to be formed on oppositely facing sidewalls, the sputtering source may be shut off during rotation of the wafer when neither sidewall is facing the sputtering source. The sputtered layer  144  has a growth morphology that results from growing outward from the base and self-shadowing from the angled deposition. This growth direction can be controlled with process parameters such as sputtering angle, and typically falls in a range between normal to the surface upon which the film is being grown and 70° to that normal. This sputtered structure of layer  144  can be observed with a transmission electron microscope (TEM) and differentiated from an electroplated layer having a similar chemical composition. The growth morphology of the sputtered layer can also help to orient the easy axis of magnetization of layer  144 . 
       FIG. 5  shows a plurality of magnetically permeable layers  146  and  148  formed on base  140  and separated by an amagnetic, electrically insulative layer  147 , which may be used for a pole-tip affording extremely high frequency operation without harm from eddy currents. The amagnetic, electrically insulative layer  147  may be formed of Alumina or SiO 2 , for example, and may be deposited at a similar or different angle than that of one or both of the magnetically permeable layers  146  and  148 . 
       FIG. 6  shows that portions of layer  144  that lie atop the base  140  and insulating layer  113  have been removed, for example by ion beam milling or other anisotropic removal as indicated by arrows  150 , leaving the vertical portion of layer  144  adjoining sidewall  142 . For the example of ion beam etching (IBE), the beam direction  150  should be within about ten degrees from normal to the wafer surface, and may be static or rotating. 
       FIG. 7  depicts an embodiment in which base layer  140  can be selectively removed, such as when the base is formed of photoresist. In this case, chemical or other removal of the base layer can leave the narrow vertical portion of the magnetically permeable material layer  144  standing naked atop the insulating layer  113 . The insulating layer  113  is to become the amagnetic gap  118  of  FIG. 3 , while magnetically permeable layer  144  is to become the narrow pole-tip  105  of  FIG. 3 , with the novel pole-tip layer oriented substantially perpendicular to the gap layer. 
       FIG. 8  depicts an embodiment in which base layer  140  has been formed of a ceramic layer or other hard, amagnetic, electrically insulating layer, such as Alumina, and remains intact adjacent magnetic layer  144 . In this case, a similar hard, amagnetic, electrically insulating layer  148 , such as Alumina may be formed on the other side of the perpendicular pole-tip layer  144 , encasing that layer  144 . The hard layers  144  and  148  are then polished, such as by a chemical-mechanical polish, to form a flat surface, trimming the magnetic layer  144  to form a pole-tip  105 , resulting in a structure similar to that shown in  FIG. 9 . 
       FIG. 9  shows that the perpendicular pole-tip layer  144  of  FIG. 7  has been surrounded by hard, amagnetic, electrically insulating material that was then planarized, such as by mechanical or chemical-mechanical polishing (CMP), to form a flat surface for layer  152  and to define the length of pole-tip  225 . The same planarizing step removes Permalloy that may have formed atop layer  117 , and may result in removal of some of layer  117  or a slight thickening of that layer from adding some of layer  152 . 
     Referring again to  FIG. 3 , atop layer  117  and the exposed pole-tip  105  a second magnetically permeable yoke layer  130  is formed by sputtering and/or electroplating. The mask through which the yoke was formed has an edge  132  that overlaps the pole-tip but does not extend as close to the media-facing surface as the pole-tip. In an alternative embodiment, not shown in this figure, the yoke layer  130  extends as close to the media-facing surface as the pole-tip  105 , forming a T-shaped pole-tip when viewed from the media-facing surface. A layer  155  of hard, amagnetic, electrially insulating material such as Alumina or DLC is formed over and around the second yoke layer  130 , and after planarization of those layers a small portion of layer  155  is disposed between the yoke layer  130  and the overcoat  106 . Another layer  135  of hard, amagnetic, electrically insulating material such as Alumina or DLC is formed atop the planarized second yoke layer  130  and surrounding layer  155 , protecting the transducer  102  on a trailing end  138  of the head  100 . After dicing the wafer into rows each containing multiple transducers such as transducer  102 , the rows are rotated ninety degrees and a protective overcoat  106  is then deposited while forming the media-facing surface  108 . 
       FIG. 10  shows another embodiment of a head  200  in which a trailing pole-tip  205  for a transducer  202  is formed subsequent to formation of a coil layer  220  but prior to formation of a second yoke layer  230 . Much as with the prior embodiment, the head  200  includes a substrate  207 , first shield layer  210 , MR sensor  212  encased in amagnetic, electrically insulating material  214 , and a second shield layer  215  that also serves as a first yoke. 
     Adjoining the first yoke layer  215  in this embodiment, however, a first magnetically permeable pole-tip  216  is formed, surrounded by amagnetic, electrically insulating material  217 . This leading pole-tip  216  may be formed by conventional techniques of electroplating through a mask and then ion milling to remove a seed layer and to optionally thin the pedestal. A closure pedestal  219  made of magnetically permeable material may be formed at the same time as the leading pole-tip  216 , although it is known that a magnetically permeable loop can be formed by the yokes and pole-tips despite small discontinuities in magnetically permeable material. Pole-tip  216  may help to focus magnetic flux transferred to and from the trailing pole-tip  205 . Since the trailing pole-tip  205  provides magnetic flux to the media that can erase prior flux provided by the leading pole-tip  216 , the leading pole-tip may be wider than the trailing pole-tip. Alternatively, the leading pole-tip may be formed by overetching of the trailing pole-tip  205  that removes portions of the gap layer  213  and first yoke  215  not covered by trailing pole-tip  205 , aligning the pole-tips. For this situation, a first protective coating may first be deposited on the trailing pole-tip before overetching, and a second protective coating deposited on the first yoke  215  after the overetching, to allow removal of possible redeposited magnetic material adjacent the gap, for example with an angular IBE. For an embodiment in which the trailing pole-tip  205  has been made extremely thin in accordance with the present invention, the leading pole-tip  216  may also be formed on a sidewall in a layer aligned with the trailing pole-tip, much as described above with regard to  FIGS. 4–9 . The closure pedestal  219  may be formed before or after the leading pole-tip  216  for this embodiment. A conductive coil  220  is formed by sputtering, electroplating and ion milling on the surface of the insulating layer  217 , and then an amagnetic, electrically insulating layer  213  is formed, which will become the write gap  218 . 
       FIG. 11  shows a cutaway perspective view of a deposition step in creating the trailing pole-tip  205  of  FIG. 10 . A photoresist mask layer  240  blankets the amagnetic, electrically insulating layer  213 , except for an aperture having a substantially vertical sidewall  244  upon which the pole-tip  205  is to be formed. For clarity, only the layers immediately beneath the insulating layer  213 , consisting of the first pole-tip  216  and insulating layer  217 , are shown in this figure. A magnetically permeable, high B s  material is sputtered at a static angle depicted by arrows  242 , coating wall  244  as well as a major surface  248  of resist layer  240 , but avoids a slightly shadowed wall  246  adjacent to coils  220 , not shown in this figure. An IBE directed substantially normal to the major surface then removes the magnetically permeable, high B s  material from the photoresist surface and from the surface of layer  213  exposed through the mask, leaving a layer of high B s  material adjoining wall  244 , much as shown in  FIG. 6 . The mask is then removed, leaving an isolated layer of high B s  material that is to form pole-tip  205 , similar to that shown in FIG,  7 . 
     Referring again to  FIG. 10 , the isolated layer of high B s  material is then encased in amagnetic, electrically insulating material  222  and then polished to expose the trailing pole-tip  205  for connection with a second yoke layer  230 . The second yoke layer  230  extends to meet the closure pedestal  219  or, in an alternative embodiment not shown in this figure, another closure pedestal may first be formed atop pedestal  219 . A protective coating  233  is then formed at a trailing end  235  of head  200 . Note that although this embodiment shows the second yoke layer  230  adjoining a protective overcoat that forms a media-facing surface  208 , the second yoke layer may instead overlap part of the pole-tip  205  and terminate prior to the overcoat  206 , similar to the second yoke shown in  FIG. 10 . 
       FIG. 12  is a cutaway view of a media-facing side of the head  200  of  FIG. 10  focusing on the transducer  202 . The first yoke  215  and leading pole-tip  216  form a T-shaped structure, as do the second yoke  230  and trailing pole-tip  205 , separated by the write gap  218 . A leading end of the head is not shown in this figure for clarity but is located opposite the trailing end  235 , and generally encounters a portion of media passing adjacent the head immediately prior to the media portion passing by the remainder of the head, with the media portion last encountering the trailing end before moving away from the head. 
       FIG. 13  shows an embodiment of a head  250  that is formed much as described regarding  FIG. 10  prior to the formation of a conductive coil, and so is not renumbered for like elements. For a transducer  252  of  FIG. 13 , however, a trailing pole-tip  255  is formed subsequent to formation of a second yoke layer  268 . For this embodiment, a coil  257  is formed on the surface of amagnetic, electrically insulating layer  217  that was described with regard to  FIG. 10 . Another amagnetic, electrically insulating layer  260  such as photoresist is then formed on and around the coil  257 , and reflowed to create a sloping side  262  adjacent the pole-tip  255 . Yet another amagnetic, electrically insulating layer  264  is then formed which will provide the write gap  266 . A second yoke  268  may then formed by sputtering a film of Permalloy, masking an area to leave an aperture for the yoke to be grown by electroplating, removing the mask and then removing the sputtered film not covered by the electroplated layer. The mask creates an edge  270  to the yoke adjacent to where the trailing pole-tip  255  is to be formed. The pole-tip is then created much as described above with respect to  FIGS. 4–9 , and then encased in a protective layer  272  of amagnetic, electrically insulating material along a trailing end  275  of the head  250 . In the embodiment of  FIG. 12  the base layer upon which the pole-tip is formed may be made of a resist that is spun so that it does not cover a plateau  274  of the second yoke  268 , and the high B s  material that forms the pole-tip may be deposited at an angle that avoids shadowing by edge  270 . After the head has been diced from other heads on the wafer substrate  207 , another protective overcoat  277  is formed on a media-facing surface  280 . 
       FIG. 14  depicts a head  300  including a transducer having a narrow trailing pole-tip  305  that is formed prior to forming a coil layer  320 . Like previously described embodiments, head  300  includes a wafer substrate  307 , a first magnetically permeable shield layer  310 , a MR sensor  312  encased in an amagnetic, electrically insulating layer  314  and a second shield that also functions as a first yoke layer  315 . On the first yoke layer  315  a leading pole-tip  316  and a closure pedestal  319  are formed of magnetically permeable material such as Permalloy, the pole-tip and pedestal separated by an amagnetic, electrically insulating layer  317 . After polishing the pole-tip  316 , pedestal  319  and insulating layer  317 , an amagnetic, electrically insulating layer  313  of material such as alumina, silicon dioxide or diamond-like carbon is formed, creating a recording or write gap  318  between the pole-tips  305  and  316 . Atop the amagnetic layer  313  adjacent the write gap the narrow, magnetically permeable trailing pole-tip  305  may be formed as described previously with regard to  FIGS. 4–9  or  FIG. 11 , or as shown in  FIG. 15  and described below. 
       FIG. 15  is a cutaway perspective view of a base  350  that serves as a template for creating the narrow, magnetically permeable trailing pole-tip, the base disposed atop amagnetic layer  313 . The base  350  in this embodiment is a raised plateau that may be formed for example of photoresist that has been developed to have a pair of substantially vertical sides  353  and  358 , and a pair of sloping sides  354  and  355 . The substantially vertical side  353  may be an edge upon which the trailing pole-tip is deposited, and for an embodiment in which transducers are formed on the wafer surface in mirror-image patterns, an oppositely disposed, substantially vertical side  358  may be an edge upon which another trailing pole-tip is deposited. The sloping sides  354  and  355  may be created with a developing mask that transmits a graded intensity of light during development, such as a mask having opaque bars that vary in spacing or width. A magnetically permeable, high B s  material may be sputtered on the base  350  at an angle from normal to the wafer surface, as shown by arrows  357 , covering sides  353  and  354 . The deposition angle may range between zero and about eighty degrees, and may be static or rotating, depending in part whether upon whether the transducers laid out on the wafer surface have identical adjacent structures or mirror-image layouts. For the case in which the sputtering angle rotates, sides  355  and  358  are also covered with the magnetically permeable material. 
     As shown in  FIG. 16 , a subsequent anisotropic removal process, such as a substantially vertical IBE, can remove the magnetically permeable material from sides  354  and  355  without significantly thinning layers  362  and  364  of the material deposited on sides  353  and  358 , respectively. Layers  362  and  364  may then become trailing pole-tips for adjacent transducers being formed on a wafer surface. 
     Referring again to  FIG. 14 , after formation of the narrow trailing pole-tip  305 , which is then encased in protective material such as photoresist, the conductive coil layer  320  may be formed by electroplating through a mask atop a conductive seed layer, with the seed layer then removed from between the coils. An amagnetic, electrically insulating layer  322  is then formed surrounding the coils  320 , and may be reflowed to create a sloping side adjacent the pole-tip  305 . A second yoke layer  330  is then formed by depositing a seed layer, then electroplating through a mask and then removing the seed layer not covered by the electroplated yoke. A protective layer  333  is then formed on what will become a trailing end  335  for the head  300 . The wafer is then diced and a protective coating  306  may be formed on what will become a media-facing surface  308  for the head. 
       FIG. 17  shows a view of the transducer  302  from the trailing end, which for clarity only shows the active components formed over the amagnetic layer  313 . The coils  320  wind around between the amagnetic layer  313  and the second yoke  330 , which tapers to adjoin the narrow trailing pole-tip  305 . 
       FIG. 18  shows an embodiment of a head  370  that is formed like that described regarding  FIG. 14  prior to surrounding a conductive coil  372  with an amagnetic, electrically insulating material  373 , and so is not renumbered for like elements. For a transducer  382  of  FIG. 18 , however, the amagnetic, electrically insulating layer  373  may be reflowed to cover most of the trailing pole-tip  305 , creating a sloping side  383  adjacent the pole-tip  305  while leaving that pole-tip partially exposed. A second yoke  388  is then electroplated that covers the exposed portion of the pole-tip, the yoke tapered and sloping to provide a maximum flux intensity adjacent the write gap  318 . 
       FIG. 19  shows an embodiment of a head  400  that is formed like that described regarding  FIG. 18  prior to surrounding the conductive coil  372  with an amagnetic, electrically insulating material  403 , and so is not renumbered for like elements. For a transducer  402  of  FIG. 19 , however, the pole-tip  305  is encased in an amagnetic, electrically insulating material, not shown in this cross-sectional view, leaving a surface of the pole-tip exposed distal to the gap  318 . An amagnetic, electrically insulating layer  403  such as photoresist is then formed, surrounding and covering the coil layer  372  and exposed surface of pole-tip  305 . The part of layer  403  covering the pole-tip  305  and closure pedestal  319  is then removed, and a second yoke  408  is then electroplated that covers the exposed portion of the pole-tip  305  and pedestal  319 . In an alternative embodiment the second yoke  408  terminates further from the media-facing surface  308  than does the trailing pole-tip  305 . 
       FIG. 20  shows an embodiment of a head  450  with a transducer  452  that is formed like that described regarding  FIG. 20  up to forming the leading pedestal  316  and closure pedestal  319 . An amagnetic, electrically insulating layer  453  is then formed that is to provide a write gap  458 . A trailing pole-tip  455  is then formed as described with regard to  FIGS. 4–9 ,  FIG. 11  or  FIG. 15 . A conductive coil  457  is then formed, and then surrounded with an amagnetic, electrically insulating material  464  that also covers the trailing pole-tip  455 . The insulating material  464  is then planarized to expose the trailing pole-tip  455  and trimmed to expose closure pedestal  319 . A second magnetically permeable yoke  466  is then formed atop the insulating layer  464 , the pole-tip  455  and the pedestal  319 . In an alternative embodiment the coil layer may be made thinner so that the second yoke layer  466  can be essentially coplanar with the pole-tip  455 , adjoining the pole-tip distal to a media-facing surface  488  rather than adjoining the pole-tip distal to the gap layer  453 . A protective coating  470  is then formed on a trailing end  474  of the head. After separating the head  450  from other heads of the wafer substrate  307 , another protective coating  480  may be formed on the media-facing surface  488 . 
       FIG. 21  shows a head  500  like that of  FIG. 20 , except that a media-facing surface  505  has been relieved so that pole-tips  316  and  455  protrude compared to yokes  315  and  466 , shield  310  and MR sensor  312 . This relative protrusion of the pole-tips  316  and  455  decreases fringe fields of the yokes  315  and  466  that may otherwise be felt by a media with which the head communicates. Recession of the MR sensor  312  relative to the pole-tips helps to avoid damage to the MR sensor and false signals from thermal asperities that may otherwise be caused by high-speed contact with the media. The protrusion of the pole-tips  316  and  455  relative to the yokes  315  and  466  and MR sensor  312  may range between about 40 Å and 0.1 μm, and may be different amounts for the first yoke  315 , second yoke  466  and MR sensor  312 . Relieving of the media-facing surface  505  may occur after the head  500  has been diced into rows and rotated to form an air-bearing or media-contacting surface. After relieving the media-facing surface  505  a protective overcoat  510  may be applied to some or all of that surface. This approach may be used with any of the above-described heads, as well as other embodiments not listed above. 
       FIG. 22  shows the head  500  of  FIG. 21  interacting with a media  550 , such as a rigid or flexible magnetic disk or tape, or magneto-optical disk or tape for the case in which the head has an optical rather than an MR sensor. For the case in which the media  550  is a rigid disk, a wafer substrate  552  is shown that may be made of glass, SiC, aluminum, or any of a number of other materials known in the art. The substrate may or may not be roughened or patterned, as is known in the art, and is covered with an underlayer  555  that may provide adhesion and a desired structure for a media layer  560  formed on the underlayer. The media layer  560  may be a conventional cobalt (Co) based alloy, which may include elements such as chromium (Cr), platinum (Pt) and tantalum (Ta), for instance. Although a single media layer  560  is shown for conciseness, layer  560  may actually represent several layers as is known, and may be designed for longitudinal or perpendicular data storage. The underlayer  555  may include Cr, nickel aluminum (NiAl), magnesium oxide (MgO) or other materials known in the art, and may be formed of more than one layer. Atop the media layer  560  a thin layer  562  of DLC, ta-C, or SiC is formed, creating a dense, hard surface  565  for the disk  550 . The layer  562  may have a thickness in a range between about 8 Å to 100 Å, similar to that of head overcoat layer  510 . 
     The disk  550  is moving relative to the head  500  in a direction shown by arrow  570 , while the head may be positioned over a single concentric data track of the disk or may be sweeping across the disk in a direction into or out of the paper of this cross-sectional drawing. The disk may be rotating at various speeds known in the art, so that the relative speed in the direction of arrow  570  may range between a few meters per second and well over ten meters per second. A layer of air or other ambient gas accompanies the rapidly spinning disk surface  565  and interacts with the media-facing surface  505  of the head  500 , causing the head in this embodiment to levitate slightly from the disk. In other embodiments, the head may be designed to operate in occasional, frequent or continuous physical contact with the disk. The head surface  505  is separated from the disk surface  565  by a physical spacing that may range between several hundred angstroms and zero, with a preferred spacing of between about two hundred angstroms and about thirty angstroms. A lubricant including perfluorocarbon molecules or other known materials may be distributed on the disk surface  565  beneath the head. 
     Although we have focused on teaching the preferred embodiments of a novel narrow pole-tip, other embodiments and modifications of this invention will be apparent to persons of ordinary skill in the art in view of these teachings. Therefore, this invention is limited only by the following claims, which include all such embodiments and modifications when viewed in conjunction with the above specification and accompanying drawings.