Abstract:
Structures and methods for fabrication servo and data heads of tape modules are provided. The servo head may have two shield layers spaced apart by a plurality of gap layers and a sensor. Similarly, the data head may have two shield layers spaced apart by a plurality of gap layers and a sensor. The distance between the shield layers of the servo head may be greater than the distance between the shield layers of the data head. The material of the gap layers may include tantalum or an alloy of nickel and chromium. The material for the gap layers permits deposition of gap layers with sufficiently small surface roughness to prevent distortion of the tape module and increase the stability of the tape module operation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional application of U.S. patent application Ser. No. 12/916,256, filed Oct. 29, 2010, which application claims benefit of U.S. Provisional Patent Application Ser. No. 61/326,607, filed Apr. 21, 2010, which is herein incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    Embodiments of the present invention generally relate to tape modules used for magnetic recording on tapes, and more specifically to fabrication of servo and data head structures of a tape module. 
         [0004]    2. Description of the Related Art 
         [0005]    Tape modules are used to record and readback information on tapes by magnetic processes. The tape modules use servo heads to read servo tracks to align the heads for reading data stored on data tracks. The servo heads and data heads are typically formed using a sensor disposed between two shield layers and directly contacting the two shield layers. However, current servo and data head designs do not provide adequate readback in newer tape designs that require higher data densities as well as different servo track and data track densities. Additionally, the industry is moving to a tunneling magnetoresistive (TMR) sensor, which has a read gap defined by the TMR film. With current tape densities, a wider read gap is needed in both the data and servo heads, and additionally, the respective gaps must be unique to one another. 
         [0006]    It is desirable to provide new head structures and processes for forming the same that allow for achieving higher recording area density than is currently available for tape modules. 
       SUMMARY OF THE INVENTION 
       [0007]    Structures and methods for fabrication of servo and data heads of tape modules are provided. The servo head may have two shield layers spaced apart by a plurality of gap layers and a sensor. Similarly, the data head may have two shield layers spaced apart by a plurality of gap layers and a sensor. The distance between the shield layers of the servo head may be greater than the distance between the shield layers of the data head. The material of the gap layers may include tantalum or an alloy of nickel and chromium. The material for the gap layers permits deposition of gap layers with sufficiently small surface roughness to prevent distortion of the TMR barrier and increase the stability of the tape module operation. 
         [0008]    Embodiments of the present invention generally relate to tape modules, and more specifically to fabrication of servo and data head structures of a tape module. In one embodiment, a tape module is disclosed. The tape module includes a servo head structure. The servo head structure includes a first servo head shield layer, a first electrically conductive servo head gap layer disposed on the first servo head shield layer, and a second electrically conductive servo head gap layer disposed on the first electrically conductive servo head gap layer. The servo head structure also includes a servo head dielectric layer disposed on the second electrically conductive servo head gap layer and a servo head sensor disposed on the second electrically conductive servo head gap layer. The servo head also includes a third electrically conductive servo head gap layer disposed on the servo head dielectric layer and servo head sensor, a fourth electrically conductive servo head gap layer disposed on the third electrically conductive servo head gap layer, and a second servo head shield layer disposed on the fourth electrically conductive servo head gap layer. 
         [0009]    In another embodiment, tape module is disclosed. The tape module includes a data head structure. The data head structure includes a first shield layer, a first gap layer disposed on the first shield layer, a dielectric layer disposed on the first gap layer, and a sensor disposed on the first gap layer. The data head structure also includes a second gap layer disposed on the dielectric layer and sensor, and a second shield layer disposed on the second gap layer. 
         [0010]    In another embodiment, a method for forming a tape module is disclosed. The method includes forming a servo head structure on a substrate. The servo head structure is formed by a method that includes depositing a first servo head shield layer on the substrate, depositing a first electrically conductive servo head gap layer on the first servo head shield layer, depositing a second electrically conductive servo head gap layer on the first electrically conductive servo head gap layer, and forming a servo head sensor on the second electrically conductive servo head gap layer. The method also includes depositing a servo head dielectric layer on the second electrically conductive servo head gap layer, depositing a third electrically conductive servo head gap layer on the servo head dielectric layer and servo head sensor, depositing a fourth electrically conductive servo head gap layer on the third electrically conductive servo head gap layer, and depositing a second servo head shield layer on the fourth electrically conductive servo head gap layer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
           [0012]      FIG. 1A  is a cross sectional view of a servo head and a data head according to one embodiment of the present invention; 
           [0013]      FIG. 1B  is a cross sectional view of a servo head and a data head according to another embodiment of the present invention; 
           [0014]      FIGS. 2A-2H  illustrate a series of top plan cross sectional views of the steps to form the servo head and the data head according to the embodiment of  FIG. 1A ; 
           [0015]      FIGS. 3A-3F  illustrate a series of cross sectional views of the steps to form the servo head and the data head according to the embodiment of  FIG. 1A ; and 
           [0016]      FIGS. 4A-4F  illustrate a series of cross sectional views of the steps to form the servo head according to the embodiment of  FIG. 1B . 
       
    
    
       [0017]    To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation. 
       DETAILED DESCRIPTION 
       [0018]    In the following, reference is made to embodiments of the invention. However, it should be understood that the invention is not limited to specific described embodiments. Instead, any combination of the following features and elements, whether related to different embodiments or not, is contemplated to implement and practice the invention. Furthermore, although embodiments of the invention may achieve advantages over other possible solutions and/or over the prior art, whether or not a particular advantage is achieved by a given embodiment is not limiting of the invention. Thus, the following aspects, features, embodiments and advantages are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s). Likewise, reference to “the invention” shall not be construed as a generalization of any inventive subject matter disclosed herein and shall not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s). 
         [0019]    Embodiments of the present invention generally relate to tape modules, and more specifically to fabrication of servo and data head structures of a tape module. Referring now to  FIG. 1A , a servo head  100  and a data head  105  are formed on a substrate surface in a spaced apart relationship according to one embodiment of the invention. It is to be understood that while only one servo head  100  and one data head  105  are shown, tape modules may have multiple servo heads  100  and multiple data heads  105 . For example, an array of up to thirty-two data heads  105  may be present and bounded by two servo heads  100 . Other combinations of data heads  105  and servo heads  100  are contemplated as well. 
         [0020]    As shown in  FIG. 1A , the servo head  100  includes a first shield layer  110 , a first gap layer  120  formed on the first shield layer  110 , a second gap layer  130  disposed on the first gap layer and any exposed portion of the first shield layer  110 , a dielectric layer  140  formed on the second gap layer  130  with a sensor  145  formed through the dielectric layer, a third gap layer  150  disposed on the dielectric layer  140  and sensor  145 , a fourth gap layer  160  disposed on the third gap layer  150 , and a second shield layer  170  disposed on the fourth gap layer  160  and any exposed portions of the third gap layer  150 . 
         [0021]    The data head  105  is formed concurrently with the servo head  100  and includes several layers in common, which are marked with the related material layer deposition. For example, the first gap layer  130 ′ of the data head corresponds to the second gap layer  130  of the servo head  100 . 
         [0022]    The data head  105  includes a first shield layer  110 ′, a first gap layer  130 ′ conformally formed on the first shield layer  110 ′, a dielectric layer  140 ′ formed on the first gap layer  130 ′ with a sensor  145 ′ formed through the dielectric layer, a second gap layer  150 ′ conformally disposed on the dielectric layer  140 ′ and sensor  145 ′, and a second shield layer  170 ′ disposed on the second gap layer  150 ′. 
         [0023]    The first and second shield layers are each formed by an electrodeposition process, such as electroplating or electroless deposition. The first and second shield layers each comprise a magnetic material selected from the group consisting of nickel-iron alloy, cobalt-iron alloy, cobalt-nickel-iron alloy, and combinations thereof. A nickel-iron alloy of 80 atomic percent nickel and 20 atomic percent iron may be used as the first and second shield layer material. The first shield layer may be formed on or in a substrate surface material of alumina (Al 2 O 3 ) or any other suitable material. 
         [0024]    The first gap layer, the second gap layer, the third gap layer, and the fourth gap layer each comprise a non-magnetic material selected from the group consisting of an alloy of nickel and chromium, tantalum, and combinations thereof. The first gap layer, the second gap layer, the third gap layer, and the fourth gap layer may be deposited by a physical vapor deposition process (PVD or sputtering) and two or more of the deposition processes may be performed in the same chamber or same processing tool. After each layer is deposited, the layer may be patterned utilizing milling or photolithographic processing. 
         [0025]    The first gap layer, the second gap layer, the third gap layer, and the fourth gap layer may be deposited each at a thickness from about 40 nm to about 90 nm (nanometers), however, any thickness may be used based on the desired gap distances and sizes of the respective heads for the tape modules. For example, the first gap layer may comprise 80 nm of NiCr alloy, the second gap layer of 45 nm of NiCr alloy, the third gap layer of 45 nm NiCr alloy, and the fourth gap layer may be deposited 80 nm of NiCr alloy. 
         [0026]    The dielectric layer may also be deposited by a physical vapor deposition process (PVD or sputtering) and may be performed in the same chamber or same processing tool with the one or more gap deposition processes. The dielectric layer may comprise a suitable dielectric material, such as a dielectric material selected from the group of aluminum oxide, silicon oxide, silicon nitride, and combinations thereof. 
         [0027]    The first and second shield layers  110 ,  110 ′,  170 ,  170 ′ may be spaced apart by the gap layers. The servo head  100  has a greater spacing between shield layers  110 ,  170  than the data head  105  in the embodiment of  FIG. 1A . In the embodiment of  FIG. 1B , the spacing for the servo head  100  and data head  105  may be substantially identical. 
         [0028]    Referring now to  FIG. 1B , a servo head  100  and a data head  105  are formed on a substrate surface in a spaced apart relationship according to one embodiment of the invention. As shown in  FIG. 1B , the servo head  100  includes a first shield layer  110 , a first gap layer  120  formed in the first shield layer  110 , a second gap layer  130  disposed on the first gap layer  120  and any exposed portion of the first shield layer  110 , a dielectric layer  140  formed on the second gap layer  130  with a sensor  145  formed through the dielectric layer, a third gap layer  150  disposed on the dielectric layer  140  and sensor  145 , a fourth gap layer  160  disposed on the third gap layer  150 , and a second shield layer  170  disposed on the fourth gap layer  160  and any exposed portion of the third gap layer  150 . 
         [0029]    The data head  105  is formed concurrently with the servo head  100  and includes several layers in common, which are marked with the related material layer deposition. For example, the first gap layer  130 ′ of the data head corresponds to the second gap layer  130  of the servo head  100 . 
         [0030]    The data head  105  includes a first shield layer  110 ′, a first gap layer  130 ′ conformally formed on the first shield layer  110 ′, a dielectric layer  140 ′ formed on the first gap layer  130 ′ with a sensor  145 ′ formed through the dielectric layer, a second gap layer  150 ′ conformally disposed on the dielectric layer  140 ′ and sensor  145 ′, and a second shield layer  170 ′ disposed on the second gap layer  150 ′. 
         [0031]    The first and second shield layers are each formed by an electrodeposition process, such as electroplating or electroless deposition. The first and second shield layers each comprise a magnetic material selected from the group consisting of nickel-iron alloy, cobalt-iron alloy, cobalt-nickel-iron alloy, and combinations thereof. A nickel-iron alloy of  80  atomic percent nickel and  20  atomic percent Iron may be used as the first and second shield layer material. 
         [0032]    The first gap layer, the second gap layer, the third gap layer, and the fourth gap layer each comprise a non-magnetic material selected from the group consisting of an alloy of nickel and chromium, tantalum, and combinations thereof. The first gap layer, the second gap layer, the third gap layer, and the fourth gap layer may be deposited by a physical vapor deposition process (PVD or sputtering) and may be performed in the same chamber or same processing tool. After each layer is deposited, the layer may be patterned utilizing milling or photolithographic processing. 
         [0033]    The first gap layer, the second gap layer, the third gap layer, and the fourth gap layer may be deposited each at a thickness from about 40 nm to about 90 nm (nanometers), however, any thickness may be used based on the desired gap distances and sizes of the respective heads for the tape modules. For example, the first gap layer may comprise 80 nm of NiCr alloy, the second gap layer of 45 nm of NiCr alloy, the third gap layer of 45 nm NiCr alloy, and the fourth gap layer may be deposited 80 nm of NiCr alloy. 
         [0034]    The dielectric layer may also be deposited by a physical vapor deposition process (PVD or sputtering) and may be performed in the same chamber or same processing tool with the one or more gap deposition processes. The dielectric layer may comprise a suitable dielectric material, such as a dielectric material selected from the group of aluminum oxide, silicon oxide, silicon nitride, and combinations thereof. 
         [0035]      FIGS. 2A-2H  illustrate a series of top plan views of the steps to form the servo head and the data head according to the embodiment of  FIG. 1A .  FIGS. 3A-3F  illustrate a series of cross sectional views of the steps to form the servo head and the data head according to the embodiment of  FIG. 1A . The method described herein may be used for creating two different shield to shield gaps on the same substrate for the servo head and the data head. 
         [0036]      FIG. 2A  illustrates a top plan view of the shaped first shield layers  210  and  210 ′ of a servo head structure  201  of the servo head portion  203  of a substrate  200  and a data head structure  202  of the data head portion  204  of the substrate  200  respectively being formed on the substrate  200 . Line  205  represents where the formed substrate will be removed to form an air bearing surface (ABS).  FIG. 3A  is a schematic cross-section view of the servo head structure  201  and a data head structure  202  along line  205 . The first shield layers  210 ,  210 ′ may each be deposited by an electrodeposition process, such as electroplating or electroless deposition. The first shield layers  210 ,  210 ′ may each comprise a magnetic material selected from the group consisting of nickel-iron alloy, cobalt-iron alloy, cobalt-nickel-iron alloy, and combinations thereof. A nickel-iron alloy of 80 atomic percent nickel and  20  atomic percent iron may be used as the first shield layer  210 ,  210 ′ material. Once deposited, the first shield layers  210 ,  210 ′ may be full film overcoated with a dielectric such as alumina and then chemical mechanical polished (CMP) for planarization and minimization of the surface roughness. 
         [0037]    The first gap layer  220  is then formed on the servo head portion shield layer  210  as shown in  FIG. 2B  and  FIG. 3B . The first gap layer  220  may comprise a non-magnetic material selected from the group consisting of an alloy of nickel and chromium, tantalum, and combinations thereof. The first gap layer  220  may be deposited by a physical vapor deposition process (PVD or sputtering). The first gap layer  220  is not present on the data head portion shield layer  210 ′. 
         [0038]    In one embodiment, the first gap layer  220  may be formed by blanket depositing first gap layer  220  material over the both first shield layers  210 ,  210 ′ and then patterning the deposited material. The patterning may comprise forming a mask over the deposited layer and the milling or etching the portions of the material not covered by the mask. The mask is then removed to leave the first gas layer  220  on the first shield layer  210  of the servo head structure  201 . 
         [0039]    In another embodiment, the first gap layer  220  may be formed by first depositing a photoresist layer and developing the photoresist layer to form a mask. Thereafter, the first gap layer  220  is deposited on the exposed portions of the first shield layer  210 . The mask is then removed leaving the first gap layer  220  formed over the servo head structure  201 . During the formation of the first gap layer  220 , the sidewalls may be tapered. The first gap layer  220  may be formed to be about 25 μm by about 30 μm (height by width) in a shield layer of about 38 μm by 60 μm. 
         [0040]    The second gap layer  230  of the servo head portion  203  and the corresponding first gap layer  230 ′ of the data head portion  204  are deposited on the first gap layer  220  and the exposed portion of the shaped first shield layers  210  and  210 ′ as shown in  FIG. 2C  and  FIG. 3C . The second gap layer  230  and first gap layer  230 ′ may each comprise a non-magnetic material selected from the group consisting of an alloy of nickel and chromium, tantalum, and combinations thereof. The material for the second gap layer  230  and first gap layer  230 ′ is selected to minimize the surface roughness of the deposited layer so that the sensor  245 ,  245 ′ may be deposited thereover. If no gap layers were used and the sensors were simply deposited on the shield layers, the shield layers would be polished to obtain a desired surface roughness. However, because the gap layers are significantly thinner than the shield layers, polishing of the gap layers may not be desirable. Therefore, the choice of material for the gap layers will affect the surface roughness. It has surprisingly been found that non-magnetic material selected from the group consisting of an alloy of nickel and chromium, tantalum, and combinations thereof for any of the gap layers will be sufficient to obtain the desired surface roughness when deposited by a physical vapor deposition process. It has been observed that if the film roughness of the gap layers is sufficiently great, strong coupling between the free and pin layers of the sensor  245 ,  245 ′ occurs that causes distortion and instability in the readback signal. The surface roughness that is obtained utilizing the specific materials (e.g., nickel-chromium alloy or tantalum) discussed herein has been found to be sufficiently small to prevent distortion and improve stability. 
         [0041]    The second gap layer  230  and first gap layer  230 ′ may be deposited by a physical vapor deposition process (PVD or sputtering). The first gap layer  220  and the second gap layer  230  on the servo head portion  203  form a first spacer between the first shield layer  210  and the sensor  245 . The second gap layer  230  and first gap layer  230 ′ may be formed by blanket depositing the material over the substrate  200 , first gap layer  220 , exposed portions of the first shield layer  210 , and the first shield layer  210 ′. Once deposited, the material is then removed from selected portions to leave the material around the data and servo head area. 
         [0042]    The dielectric layer  240  and sensor  245  of the servo head portion  203  and the corresponding dielectric layer  240 ′ and sensor  245 ′ (not shown in  FIG. 2D ) of the data head portion  204 , are then formed on the second gap layers  230  and  230 ′ respectively as shown in  FIG. 2D  and  FIG. 3D . The sensors  245  and  245 ′ may be of any type of suitable sensor used for the manufacturing of TMR devices. In one embodiment, the sensors  245 ,  245 ′ are formed by depositing multiple material layers and then etching back the layers, either individually or collectively, to form the final sensors  245 ,  245 ′. The dielectric layers  240 ,  240 ′ are then formed by blanket depositing the dielectric material, forming a photoresist mask thereover, and removing the exposed dielectric material. The exposed dielectric material that is removed is formed over the sensors  245 ,  245 ′. Thus, after removal of the exposed dielectric material, the dielectric material will remain everywhere except over the sensors  245 ,  245 ′. The photoresist mask is then removed. Alternatively, the dielectric layers  240 ,  240 ′ may be formed by first forming a photoresist mask over the sensors  245 ,  245 ′and then depositing the dielectric layers  240 ,  240 ′ on the gap layers not covered by the mask. The photoresist mask is then removed. In an alternative embodiment, the dielectric layers  240 ,  240 ′ may be formed prior to forming the sensors  245 ,  245 ′. 
         [0043]    The third gap layer  250  of the servo head portion  203  and the corresponding second gap layer  250 ′ of the data head portion  204 , are deposited on the dielectric layer  240  and sensor  245  of the servo head portion  203  and corresponding dielectric layer  240 ′ and sensor  245 ′ (not shown in  FIG. 2D ) of the data head portion  204 , as shown in  FIG. 2E  and  FIG. 3E . The third gap layer  250  and second gap layer  250 ′ may each comprise a non-magnetic material selected from the group consisting of an alloy of nickel and chromium, tantalum, and combinations thereof. The material for the third gap layer  250  and second gap layer  250 ′ is selected to minimize the surface roughness of the deposited third gap layer  250  and second gap layer  250 ′at the interface with the sensors  245 ,  245 ′. The third gap layer  250  and second gap layer  250 ′ may be deposited by a physical vapor deposition process (PVD or sputtering). The third gap layer  250  and second gap layer  250 ′ may be deposited and then etched or milled back to the desired final shape. 
         [0044]    After the third gap layer  250  and second gap layer  250 ′ are formed, the fourth gap layer  260  is deposited and patterned on the third gap layer  250  of the servo head portion as shown in  FIG. 2F  and  FIG. 3F . The fourth gap layer  260  may comprise a non-magnetic material selected from the group consisting of an alloy of nickel and chromium, tantalum, and combinations thereof. The material for the fourth gap layer  260  may comprise the same material as the third gap layer  250 . The fourth gap layer  260  may be deposited by a physical vapor deposition process (PVD or sputtering). The fourth gap layer  260  deposition process includes the deposition of the fourth gap layer  260  material followed by an etching process, such as an ion milling process using a lithographic patterning process, to remove some of the fourth gap layer  260  material forming tapered sides and exposing portions of the underlying of the underlying third gap layer  250  material. The third gap layer  250  and the fourth gap layer  260  form a second spacer between the second shield  270  and the sensor  245 . 
         [0045]    The second shield layer  270  of the servo head portion  203  and the corresponding second shield layer  270 ′ of the data head portion  204 , is deposited on the third gap layer  250  and fourth gap layer  260  of the servo head portion  203 , and the second gap portion  250 ′ of the data head portion  204 , as shown in  FIG. 2G  and  FIG. 3F  to form the structures as shown in  FIG. 1A . The second shield layers  270 ,  270 ′ may have a different area than the first shield layers  210 ,  210 ′. In general, the second shield layers  270 ,  270 ′ may each be sufficient in size to cover the sensors  245 ,  245 ′ entirely. Each of the shield layers  210 ,  210 ′,  270 ,  270 ′ may be deposited to a thickness between 0.5 μm and 2.0 μm, such as 1 μm. In order to deposit the second shield layers  270 ,  270 ′ by electrochemical plating or electroless plating, a seed layer is first deposited by sputtering. The seed layer is blanket deposited. Then, the second shield layers  270 ,  270 ′ are deposited through a photoresist mask. The photoresist mask is then removed. The seed layer that was covered by the mask may then be removed by an etching process. 
         [0046]    A protective layer may be deposited over the two portions for completion of the device prior to forming the air bearing surface as shown in  FIG. 2H . In one embodiment, the protective layer may comprise alumina. Vias  208  may be etched through the alumina layer to permit electrical connection of the servo head portion  203  and data head portion  204  to bonding pads using high conductivity leads. 
         [0047]      FIG. 4A  is a schematic cross-section view of a servo head structure  201  along line  205  according to the servo head structure of  FIG. 1B . The shaped shield layer  210  is formed on the substrate  200  as shown in  FIG. 4A . A feature definition  215  is formed in the shaped shield layer  210  surface. The feature definition  215  may be formed by any conventional process, such as ion milling, and is preferably formed with tapered (from the bottom to top of the feature definition) or vertical sides. The feature definition  215  is milled to a targeted depth. 
         [0048]    The first gap layer  220  material is deposited in the feature definition  215  with a thickness equal to the targeted depth of the feature definition  215 . The formation of the feature definition  215  and the deposition of the first gap layer  220  may occur utilizing the same photolithographic mask. For example, after the shield layer  210  is deposited on a substrate  200 , a photolithographic mask is formed by depositing a photoresist and then developing the photoresist to form the mask. The shield layer  210  is then selectively milled or etched using the mask so that the feature definition  215  is formed. Then, utilizing the same mask, the first gap layer  220  is deposited into the feature definition  215 . The mask and any of the first gap layer that is deposited thereon is then removed. 
         [0049]    The second gap layer  230  is conformally deposited on the planar surface of the first shield layer  210  and the first gap layer  220  as shown in  FIG. 4C . The dielectric layer  240  and sensor  245  are deposited, patterned, and formed on the second gap layer  230  as shown in  FIG. 4D . The third gap layer  250  is conformally deposited on the dielectric layer  240  and sensor  245  as shown in  FIG. 4E . 
         [0050]    The fourth gap layer  260  is deposited and patterned on the third gap layer  250  as shown in  FIG. 4F . The fourth gap layer  260  deposition process includes the deposition of the fourth gap layer  260  material followed by an etching process, such as an ion milling process using a lithographic patterning process, to remove some of the fourth gap layer  260  material forming tapered ends and exposing portions of the underlying of the underlying third gap layer  250  material. 
         [0051]    The second shield layer  270  is deposited on the third gap layer  250  and fourth gap layer  260 , as shown in  FIG. 4F  to form the servo head structure as shown in  FIG. 1B . The data head structure of  FIG. 1B  is formed as described above for the data head structure of  FIG. 1A . 
         [0052]    By utilizing electrically conductive gap layers between shield layers in both the servo head and data head of a tape module, the tape module may be effective and be capable of utilizing a TMR sensor. The gap layers may comprise tantalum, an alloy of nickel and chromium, or combinations thereof. The material of the gap layers is beneficial because the gap layers will have an acceptable surface roughness without polishing, and polishing the gap layers may not be possible due to relatively small thickness of the gap layers. 
         [0053]    While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.