Abstract:
A method and system for forming a microscopic transducer are described. The method and system include forming a plurality of adjoining sensor layers. The sensor layers include a first magnetically soft layer, a nonmagnetic layer on the first magnetically soft layer, and a second magnetically soft layer on the nonmagnetic layer. The method and system also include forming a sidewall over the second magnetically soft layer. The sidewall formation includes forming a base having a surface oriented substantially perpendicular to the sensor layers and depositing an electrically conductive material on the surface. The method and system also include removing a portion of the sensor layers not covered by the sidewall.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit under 35 U.S.C. §120 of (is a Divisional of) U.S. patent application Ser. No. 09/585,988, which was filed Jun. 2, 2000, now U.S. Pat. No. 6,700,759. 
    
    
     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 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 independently 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 and track density have been limited by constraints in reducing the size of transducer features that interact with the media in recording and reading magnetic patterns. For example, inductive pole-tips and MR sensors are conventionally defined by photolithography, which limits a minimum track width for which magnetic patterns on the media can be written or read. 
       FIG. 1  (Prior Art) depicts a design for a thin film head  50  as would be seen from a media from which the head is to read magnetic signals. The head contains a spin-dependent tunneling magnetoresistive sensor  52  formed in a series of layers between first and second magnetically permeable shields  55  and  58  which also serve as leads for the sensor, as described in U.S. Pat. No. 5,898,548, incorporated herein by reference. The sensor and adjacent layers include a template layer  64  that helps with formation of a subsequently deposited antiferromagnetic layer  66 . The antiferromagnetic layer  66  stabilizes the magnetic moment of a pinned ferromagnetic layer  68 . An alumina (Al 2 O 3 ) tunneling layer  70  separates the pinned ferromagnetic layer  68  from a free ferromagnetic layer  72  that has a magnetic moment that can rotate in the presence of a magnetic field from the media. A cap layer  75  of tantalum (Ta) is formed to protect the sensor from damage, and electrically conductive spacer layers  60  and  62  separate the sensor from the shields. 
     Formation of the above-mentioned elements begins by depositing the first shield  55 , spacer layers  60  and  62 , sensor layers  64 ,  66 ,  68 ,  70  and  72 , and cap layer  75 . After depositing the spacer, sensor and cap layers on the first shield  55 , a photoresist  77  is lithographically patterned and the sensor is defined by ion milling material not protected by the resist. A width W 0  of the sensor essentially corresponds to the width of the resist, although both may be thinned during the ion milling process. Alumina  88  is deposited to fill in around the sensor and a pair of hard bias layers  78  and  80  are formed to bias free layer  72 , leaving a thick deposit of material atop the resist  77  and pointed projections  82  and  84  along the sides of the resist. The resist is chemically removed, which frees the material atop the resist  77 , and the projections are broken off during chemically/mechanical polishing (CMP), after which the spacer  62  and second shield layer  58  are formed. An effective length L 0  of the sensor for linear resolution is the spacing between the first shield  55  and second shield  58 , which may be less than 0.1 micron. 
     Control of the ion milling for thinning the sensor  52  becomes difficult for widths W 0  that are less than 0.5 micron, and errors in mask definition increase with mask thickness, but thicker masks are useful to over-etch the sensor to attempt to create spacer  60  out of shield  55 . Therefore it has been difficult for such a prior art sensor to have a length-to-width ratio greater than 1/5. Moreover, forming spacer  62  from shield  58  requires the thin cap  75  to protect the sensor from damage during CMP, such as puncturing the cap with the broken off projections  82  and  84 . Contamination such as wash chemicals or alumina from the CMP may also degrade the performance of the conductive spacer  62 . While lithographic definition can be improved somewhat by using electron beam, X-ray or deep ultra violet lithography, such techniques are extremely capital intensive and require long lead times for equipment, development and facilities construction. Moreover, techniques such as X-ray and electron beam lithography are used to form individual sensors as opposed to more efficient simultaneous definition of all sensors on a wafer surface. 
     SUMMARY 
     In accordance with the present invention, a magnetoresistive (MR) sensor is defined by an electrically conductive sidewall layer that is oriented substantially perpendicular to most if not all other layers of the sensor, allowing the sensor to be made much thinner than conventional sensors. Such a thinner sensor can read narrower media tracks without interference from neighboring tracks, affording higher track density. The novel sidewall layer may be magnetically permeable and serve as an extension of a shield for the sensor, improving linear resolution and density. For this embodiment, an exact shield-to-shield spacing can be created based upon the sensor length, which is simply the sum of the accurately deposited sensor layers. Similarly, errors in sensor thickness can be much less than standard error tolerances for conventional sensors. The connection of the shields and the sensor can be tailored to create a device having a shape that is preferred for durability and yield as well as for electrical and magnetic considerations. Another advantage is that the sensor can be formed to a narrow width by mass production along with perhaps thousands of other sensors on a wafer, by employment of relatively inexpensive tools and processes. 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 MR sensor having a narrow width. 
         FIG. 3  is a cross-sectional view of some steps in a process for making the sensor of  FIG. 2 , viewed along a cross-section located close to what will become the media-facing surface. 
         FIG. 4  is a cross-sectional view of a step in the process for making the sensor of  FIG. 2 , subsequent to that shown in  FIG. 3 . 
         FIG. 5  is a cross-sectional view of a step in the process for making the sensor of  FIG. 2 , subsequent to that shown in  FIG. 4 . 
         FIG. 6  is a cross-sectional view of a step in the process for making the sensor of  FIG. 2 , subsequent to that shown in  FIG. 5 . 
         FIG. 7  is a cross-sectional view of a step in the process for making the sensor of  FIG. 2 , subsequent to that shown in  FIG. 6 . 
         FIG. 8  is a cross-sectional view of a step in the process for making the sensor of  FIG. 2 , subsequent to that shown in  FIG. 7 . 
         FIG. 9  is a cross-sectional view of a step in the process for making the sensor of  FIG. 2 , subsequent to that shown in  FIG. 8 . 
         FIG. 10  is a cross-sectional view of a step in the process for making the sensor of  FIG. 2 , subsequent to that shown in  FIG. 9 . 
         FIG. 11  is a cross-sectional view of a step in the process for making the sensor of  FIG. 2 , subsequent to that shown in  FIG. 10 . 
         FIG. 12  is a cross-sectional view of a step in the process for making the sensor of  FIG. 2 , subsequent to that shown in  FIG. 11 . 
         FIG. 13  is a cross-sectional view of a step in the process for making the sensor of  FIG. 2 , subsequent to that shown in  FIG. 12 . 
         FIG. 14  is a cutaway view of a media-facing side of a head in accordance with the present invention focusing on a MR sensor having a narrow width. 
         FIG. 15  is a cutaway cross-sectional view of the head in of  FIG. 2  including an inductive transducer in operation reading or writing on a media. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 2  is a cutaway view of a media-facing side of a head  100  focusing on a MR sensor  101  having a narrow width W 1 . The width W 1  can be as thin as a few nanometers or less and can be as thick or thicker than conventional sensors, while a presently preferred width W 1  is in a range between about 0.5 micron and 0.01 micron. Such a narrow width W 1  allows the sensor  101  to read from thinner tracks on the media without interference from neighboring tracks. For example, a pitch or track-to-track spacing of 0.025 micron, which may be read by the sensor  101  without off-track interference, provides a track density of one million tracks per inch. 
     The head  100  includes first and second magnetically permeable shields  102  and  104 , which are formed of materials such as NiFe, and which in this embodiment have tapered regions  106  and  108  adjacent the sensor  101 . An optional electrically conductive, nonmagnetic spacer  110 , which may for instance be formed of copper (Cu) or a noble metal, adjoins the tapered section  106  of the first shield. An optional electrically conductive seed layer  112  made of a material such as tantalum (Ta) or nickel-iron-chromium (NiFeCr) is disposed between an antiferromagnetic layer  115  and spacer  110 . Antiferromagnetic layer  115  stabilizes a magnetic moment of an adjoining pinned ferromagnetic layer  118  in a direction toward or away from the media, as shown by arrow end  119 . A tunneling layer  120  made of non conducting material such as a dielectric separates pinned layer  118  from a free ferromagnetic layer  122 , which has a magnetic moment that is able to rotate in the presence of a magnetic field from a media. In the absence of a magnetic field from a media, free layer  122  has a magnetic moment substantially parallel to the media surface, as shown by arrow  123 . A second optional electrically conductive, nonmagnetic spacer  125 , which may for instance be formed of Cu or a noble metal, magnetically separates the sensor from the shield  104 . An electrically conductive sidewall layer  133 , which in this embodiment is also magnetically permeable, adjoins the spacer  125  and the tapered region  108  of the second shield. An electrically insulating, nonmagnetic fill material  135  such as alumina encircles the sensor and a pair of hard bias layers  140  and  144  that provide magnetic bias to free layer  122 . 
     An effective length L 1  of the sensor  101  for linear resolution is simply the sum of layers  110 ,  112 ,  115 ,  118 ,  120 ,  122  and  125 , each of which is exactingly formed to a thickness typically less than 50 Å, so that a total length L 1  may be less than 200 Å. Such a minute effective length L 1  sharpens the focus of the sensor and increasing linear density. Despite this minute effective length, it is possible for sensor  101  to have a length-to-width ratio greater than one. A larger spacing S 1  between regions of shield layers  102  and  104  that are distal to the sensor  101  helps to avoid shorting between those layers. Also, the greater spacing of S 1  compared to L 1  reduces the relative capacitance of between the shields compared to that of the sensor, encouraging tunneling and increasing the potential frequency of the sensor. Such a small effective length L 1  can resolve media signals at a linear density of well over one million transitions per inch. Thus the combined track and linear density provided by the present invention can resolve media signals at an areal density of over a terabit per square inch. 
     A process for making the sensor  101  is illustrated beginning with  FIG. 3 , viewed along a cross-section located close to what will become the media-facing surface. The first shield  100 , which may be made of NiFeX alloys (where X is Ta, Rh, Pt or Nb) or CoZrY alloys (where Y is Ti, Ta, Nb, or Hf), or FeAlSi alloys, may be formed by sputtering a seed layer followed by electroplating to a thickness of a few microns. The remaining layers shown in  FIG. 3  are formed by conventional vacuum deposition techniques such as RF or DC sputtering or vapor deposition. Atop the first shield  100 , optional electrically conductive, nonmagnetic spacer  110 , is formed to a thickness of between about 50 Å and 200 Å of a metal such as Cu, Pt, Pd, Au, Ag or Al. Optional electrically conductive seed  112  is made of a material such as Ta or NiFeCr and formed to a thickness of between about 5 Å and 50 Å. Antiferromagnetic layer  115  is then formed of FeMn, NiMn, CoMn or IrMn, PtMn, PtPdMn to a thickness of between about 30 Å and 250 Å. Instead of or in addition to antiferromagnetic layer  115 , a pair of magnetostatically coupled layers sandwiching a very thin noble metal layer such as ruthenium (Rh) may be employed to stabilize the moment of pinned layer  118 . Pinned layer  118  may be made of a magnetically soft ferromagnetic material such as NiFe or CoFe, or may be made of a hard bias material such as CoCr, CoPt or CoNi, or related alloys, such as CoPtT, CoPtCr, CoCrTa or CoNiPd. For the case where a hard bias material is used for the pinned layer  118 , adjacent stabilizing layers may be avoided. The tunneling layer  120  of electrically insulating material such as Al 2 O 3 , SiO 2 , SiN, SiC, AlN or Ta 2 O 5  is then formed to a thickness of between about 5 Å and 50 Å atop pinned layer  118 . For the situation in which the tunneling layer is an oxide such as Al 2 O 3  or SiO 2 , the oxide may be grown upon a deposited layer of Al or Si, for example. Free ferromagnetic layer  122  is then formed to a thickness of between about 10 Å and 70 Å atop tunneling layer  120 . The optional second spacer  125  is then formed of a material such as Cu, Pt, Pd, Au, Ag, Al, Ta or NiFeCr. 
     As shown in  FIG. 4 , a removable base layer  150  such as photoresist is formed on the second spacer  125  and patterned to have an edge  152  aligned near a desired edge of the sensor  101 . An electrically conductive material layer is then formed, creating horizontal layers  155  and  158  on the base  150  and exposed portion of spacer  125 , respectively, and forming sidewall layer  133  on edge  152 . Sidewall layer  133  may have a width in a range between about 1/2 μm and 20 nm, while extending from the sensor layers a height of between about 1/2 μm and 10 μm. The electrically conductive material of layers  133 ,  155  and  158  can be nonmagnetic, eliminating the need for an electrically conductive spacer  125  to magnetically separate free layer  122  from shield  104 . In this case, electrically conductive layers  133 ,  155 , and  158  may be made of Cu, Pt, Pd, Au, Ag, or alloys of such elements. In the embodiment shown, the layers  133 ,  155 , and  158  are also magnetically permeable, and may be made of NiFeX alloys (where X is Ta, Rh, Pt or Nb) or CoZrY alloys (where Y is Ti, Ta, Nb, or Hf), or FeAlSi alloys. The layers  133 ,  155  and  158  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. Since the layers  133  and  158  are vacuum-deposited directly on the sensor layers, a junction between layers  133  and  158  and layer  125  is free of contaminants such as alumina that may be found in prior art devices, although a perimeter of that junction will be exposed to other materials. 
     Electrically conductive layers  133 ,  155 , and  158  may be formed by anisotropic formation techniques including deposition by RF or DC sputtering at a non-normal angle Ø to a direction  160  along which the sensor layers extend, as shown by arrows  162 . The angle Ø may vary between less than 1° to more than 70°, and is preferably in a range between about 20° and 50°. Such angled deposition can be variable or static in both angle and flux, including rotating about edge  152 . In this fashion, the thickness of layer  133  can be varied compared to that of layers  155  and  158 , any of which can be made as thin as a few atoms or as thick as a few microns. The growth morphology of layer  133  is different in direction from that of layers  155  and  158  and from the sensor layers such as layers  120  and  122 , since layer  133  grows outward from edge  152 , while the other layers grow in a direction substantially normal to direction  160 . This growth direction of layer  133  can be controlled with process parameters such as sputtering angle, and typically falls in a range between normal to the surface  152  upon which the film is being grown and 70° to that normal. The growth morphology and vacuum-deposited structure of layer  133  can be observed with a transmission electron microscope (TEM) and differentiated from layers grown in a direction substantially normal to direction  160 , as well as differentiated from electroplated layers having a similar chemical composition. 
       FIG. 5  shows the preferential removal of layers  155  and  158 , leaving layer  133  substantially intact. This anisotropic removal can be accomplished by ion beam or other directed impingement of particles in a substantially normal direction to the wafer surface, as shown by arrows  164 . For the example of ion beam etching (IBE), the beam direction  164  should be within about 10° from normal to the wafer surface, and may be static or rotating. 
     After removing layers  155  and  158 , layer  150  is removed, for example by a reactive ion etching (RIE) of O 2  or a similar resist ash. Removal of layer  150  leaves layer  133  standing atop the sensor layers, as shown in  FIG. 6 . 
       FIG. 7  shows another anisotropic removal such as ion milling or other directed impingement of particles in a substantially normal direction to the wafer surface, as shown by arrows  166 . The height of layer  133  is also reduced, and that layer as well as the sensor layers may be thinned slightly. For the example of ion milling, the beam direction  166  should be within about 45° from normal to the wafer surface, and may be static or rotating. Rotation or other directional variation of the beam direction  166  can provide tapered areas  106  during etching of the first shield  102 . 
     A nonmagnetic, electrically insulating layer  170  made of alumina or similar gap materials known in the electromagnetic transducer industry is then formed on the shield and surrounding the sensor layers and sidewall layer, as shown in  FIG. 8 . For the situation in which hard bias layers are desired to reduce edge effects in the free layer  122 , layer  170  has a thickness that extends partially up sensor layers. It may also be helpful to form layer  170  of a dielectric that etches at a faster rate than a subsequently deposited dielectric, to facilitate forming tapered areas  108  shown in  FIG. 1 . 
     In  FIG. 9  a hard bias layer  172  has been formed atop layer  170  to a thickness substantially greater than that of free layer  122 . A Cr or NiAl seed may be formed prior to the hard bias formation. The hard bias layer  172  may be formed in the presence of a magnetic field and made of a material such as CoCr, Copt, or CoNi or related alloys, such as CoPtTi, CoPtCr, CoCrTa, CoNiPd, CoCrTaPt or CoCrPtB. A thinner portion  173  of hard bias layer  172  extends over sidewall  133 . 
     In  FIG. 10  the thinner portion  173  of the hard bias layer  172  has been removed, for instance by IBE at greater than 45° from normal to the wafer surface, such as at 60° to 80° from normal to the wafer surface, which may also tend to remove some of the rest of layer  172 . Another nonmagnetic, electrically insulating layer  175  made of alumina or similar materials is then formed to a thickness that extends partially up the sidewall layer  133 , as well as a forming a cap  178  over layer  133 . As mentioned above, layer  175  may be more impervious to IBE or other etching than insulating layer  170  or metallic sidewall layer  133 , so that layer  175  etches at a slower rate than layers  170  and/or  133 , helping to form tapered areas  108  shown in  FIG. 1 . 
       FIG. 11  shows the preferential removal of the cap  178 , for instance by IBE at an angle α greater than 45° from normal  182  to the wafer surface, as shown by arrows  177 . The IBE or other directed removal may be at 60° to 80° from normal to the wafer surface, which may also tend to remove some of the rest of layer  175 . A top portion of layer  170  may also be removed by this preferential removal of the cap  178  and, depending upon the height of sidewall  133 , some of that layer  133  may be removed as well. 
       FIG. 12  shows that after the preferential removal of cap  178 , the direction of IBE may be much closer to normal to the wafer surface, preferably at an angle less than 45° from normal to the wafer surface as shown by arrows  180 . The faster etch rate of layer  133  and, optionally, layer  170  as compared with layer  175  causes the formation of tapered area  133  above the sensor layers. The amount and rate of etching can be used to adjust the height of a top  184  of layer  133 . Adjustment of various processing techniques and materials discussed above can vary the shape of regions adjacent the top  184  so that the regions are essentially coplanar with top  184 , inverted compared with tapered areas  108 , or other more complicated shapes that would be apparent to those of skill in the art. Note also that the sensor layers may be formed in a reverse order by forming a free layer, then a tunneling layer, followed by a pinned layer and a pinning layer or layers. 
       FIG. 13  shows the formation of second magnetically permeable shield  104  atop the structure of  FIG. 12 . Layer  104  may be made of NiFeX alloys (where X is Ta, Rh, Pt or Nb) or CoZrY alloys (where Y is Ti, Ta, Nb, or Hf), or FeAlSi alloys, and may be formed by sputtering a seed layer followed by electroplating to a thickness of a few microns. Note that between from the formation of shield layers  102  and  104 , which may include electroplating, all other process steps may be performed in a low-pressure chamber. The lack of liquid chemicals and mechanical grinding or polishing, as well as the freedom from opening the chamber to expose the delicate sensor layers to outside contaminants, can be advantageous in avoiding damage and impurities that can destroy the sensor, lower manufacturing yields and/or decrease sensor lifetimes. 
       FIG. 14  shows a portion of a head  200  including a MR sensor  201  that has alternating thin layers of magnetic and nonmagnetic materials, both of which are electrically conductive, as described in U.S. Pat. No. 5,883,763 and U.S. Pat. No. 5,880,912, which are incorporated by reference herein. The sensor  202  is formed in accordance with the present invention between magnetically permeable first and second shields  205  and  206 , similar in composition and formation to the shields  102  and  104  described above. A first electrically conductive, nonmagentic spacer layer  208  adjoins shield  205 , followed by a ferromagnetic layer  210  that may be made of a hard bias material. A second electrically conductive, nonmagentic spacer layer  212  adjoins ferromagnetic layer  210 , followed by GMR element  215 . GMR element  215  may contain alternating thin layers of magnetic and nonmagnetic materials, both of which are electrically conductive, and which may each have a thickness less than 50 Å, with the overall thickness of GMR element  215  in a range between about 50 Å. And 500 Å. As an example, the layers may be made of Cu and Co each having a thickness of about 20 Å. 
     A third electrically conductive, nonmagentic spacer  218  adjoins GMR elements  215 , and a second ferromagnetic layer  220 , which may be made of a hard bias material, adjoins the third electrically conductive spacer  218 . An electrically conductive, nonmagentic sidewall layer  222  separates second ferromagnetic layer  220  from second shield  206 . The sidewall layer  222  may be formed much as described above for sidewall layer  133 , and may be magnetically permeable as well as electrically conductive for the situation, not shown in this figure, in which an electrically conductive, nonmagentic spacer separates the sidewall from magnetic layer  230  or shield  206 . Nonmagentic, electrically insulating material  225  encases sensor  202  and separates shields  205  and  206 . 
       FIG. 15  shows head  100  for an embodiment that includes an optional inductive transducer  300  having a narrow trailing pole-tip  303 , as disclosed in U.S. patent application Ser. No. 09/500,380, invented by Kenneth E. Knapp et al. and incorporated by reference herein. The head  100  is formed on a substrate  305 , and after formation of the shields  102 ,  104  and MR sensor  101 , the inductive transducer  300  is formed, which may be separated from shield  104  by a nonmagentic, electrically insulating layer  304 , forming a piggyback head. In an alternative embodiment, not shown, this shield and yoke are merged to form a merged head. Inductive transducer  300  includes first and second magnetically permeable yoke layers  308  and  310  sandwiching an electrical coil layer  313 , separated by nonmagentic, electrically insulating layers  315  and  317 . The narrow trailing pole-tip  303  is formed on a sidewall in a similar fashion as described above for sidewall layer  133 , to a width that may be comparable but somewhat larger than the width W 1  of sensor  101 . After formation and over-etching of the sidewall to form a tapered portion of yoke  308 , a nonmagentic, electrically insulating material such as alumina may be deposited and then polished to form a planar surface for forming yoke  310 . 
     A protecting coating  320  is then formed on the wafer surface, which after dicing the wafer to separate head  100  from other heads becomes trailing end  322 . Another protective coating  323  is applied to a surface  325  of the head that in operation faces a media  330 , a portion of the media being shown in  FIG. 15 . The coating is thin and may be transparent, so as the media facing side of the head displays features such as those shown in  FIG. 2  or  FIG. 14 . The media  330  may for example be a rigid disk including a disk substrate  333 , and undercoat or template  335 , a media layer or layers  338 , and a protective overcoat  340  on a media surface  342 . The media may travel in the direction of arrow  344  relative to head  100 . During this relative motion, the narrow pole-tip  303  may write and/or the narrow sensor  101  may read signals on the media along a track that is substantially parallel with arrow  344 . 
     Although we have focused on teaching the preferred embodiments of a novel narrow sensor and head, 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.