Patent Publication Number: US-9426886-B2

Title: Electrical connection with reduced topography

Description:
SUMMARY 
     Implementations described and claimed herein provide for a layered microelectronic structure comprising a basecoat layer on a substrate; an electrical via in the basecoat layer that contacts the substrate and has a base portion and an upper portion, the upper portion having an outer casing and an interior prong; and a contact pad that contacts the upper portion and is axially aligned with the base portion and the upper portion. 
     This Summary is provided to introduce an election of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Other features, details, utilities, and advantages of the claimed subject matter will be apparent from the following more particular written Detailed Description of various implementations and implementations as further illustrated in the accompanying drawings and defined in the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an example air-bearing surface of a transducer head manufactured using NIL and/or optical lithography techniques. 
         FIG. 2  illustrates a first example photoresist exposure and development step in creating substrate electrical connections in a transducer head. 
         FIG. 3  illustrates an example substrate-etching step in creating substrate electrical connections in a transducer head according. 
         FIG. 4  illustrates a photoresist deposition step in creating substrate electrical connections in a transducer head according to another implementation. 
         FIG. 5  illustrates another example photoresist exposure and development step in creating substrate electrical connections in a transducer head. 
         FIG. 6  illustrates an example electroplating step in creating substrate electrical connections in a transducer head. 
         FIG. 7  illustrates an example result of a feature-building step in creating substrate electrical connections in a transducer head. 
         FIG. 8  illustrates yet another example photoresist exposure and development step in creating substrate electrical connections in a transducer head. 
         FIG. 9  illustrates yet another example electroplating step in creating substrate electrical connections in a transducer head according. 
         FIG. 10  illustrates an example additional basecoat layer application step in creating substrate electrical connections in a transducer head. 
         FIG. 11  illustrates an example contact pad connection step in creating substrate electrical connections in a transducer head. 
         FIG. 12  illustrates a flow-chart of example operations for creating substrate electrical connections of a transducer head that result in a reduced wafer topography. 
     
    
    
     DETAILED DESCRIPTION 
     Improvements in magnetic storage media technology allow for the areal recording densities on magnetic discs that are available today. However, as areal recording densities increase, smaller and more sensitive thin film heads are desired. Fabrication of thin film heads for densities above 1 Tbpsi require the formation of complex feature geometries that may not readily and cost-effectively be created using traditional optical lithography techniques or by alternatives such as ebeam lithography. These complete feature geometries can, however, be created using NanoImprint Lithography (NIL) techniques. 
     NanoImprint lithography (NIL) offers advanced pattern fidelity similar to ebeam lithography, but is significantly faster and offers throughput similar to optical lithography. Unlike optical lithography patterning, NIL patterning relies on direct contact between a wafer and a template that is pressed against the wafer. This direct contact permits capillary forces to draw droplets of liquid photoresist on the wafer into patterned grooves on the template. However, when significant topography is present on the wafer prior to NIL imprinting, such capillary forces may be insufficient to draw the liquid photoresist into the cavities. In such cases, NIL imprinting can be problematic. 
     As used herein, the term “significant surface topography” refers to topographical features created on the surface of a wafer that are large to be problematic in a NIL imprinting process. For example, significant surface topography may refer to features large enough to prevent a NIL template from making direct and substantially uniform contact with a photoresist on the wafer during NIL patterning. Typically, such contact is prevented when two or more microns of topography are present on the surface of the wafer. However, such contact may be prevented in other implementations when there is substantially between 0.5 and 1.0 μm of topography on the wafer. Alternatively, significant surface topography may refer to features less than 0.5 microns that create other problems in NIL patterning. 
     One source of significant surface topography in thin film head creation is the addition of substrate electrical connections to the thin film heads. Although polishing processes can remove some surface topography, polishing is time consuming and can create wafer uniformity problems when 2.5 microns of topography or greater are present on the wafer. Additionally, polishing is not always time or cost efficient. Implementations of the methods disclosed herein significantly reduce surface topography formed incident to the creation of substrate electrical connections on a transducer head. 
       FIG. 1  illustrates an example air-bearing surface of a transducer head  100  manufactured using NIL and/or optical lithography techniques. The transducer head  100  is a laminated structure with a variety of layers performing a variety of functions. A substrate  103  serves as a mounting surface for the transducer head  100  components and connects the transducer head  100  to an air-bearing slider (not shown). The substrate  103  is preferably a hard material with high thermal stability, such as aluminum-titanium carbide (AlTiC). In one implementation, the substrate  103  is a layer of AlTiC that is approximately 1210 μm thick. 
     A nonmagnetic, nonconductive basecoat  104  is deposited on the substrate  103 . The basecoat  104  may be, for example, aluminum oxide (Al 2 O 3 ), silicon oxynitride (Si x O y N z ), aluminum nitride, silicon nitride, or silicon oxide. In one implementation, the basecoat layer  104  has a height (y-direction) that is substantially between three and ten microns thick. 
     A read element  102  is sandwiched between a lower shield  106  and an upper shield  108 . The shields  106  and  108  isolate the read element  102  from electromagnetic interference, primarily y-direction interference, and serve as electrically conductive first and second electrical leads connected to processing electronics (not shown). Further, side shields  110  isolate the read element  102  from electromagnetic interference, primarily x-direction interference and/or z-direction interference. Nonmagnetic, nonconductive isolation layers  112  electrically isolate the lower shield  106  and the read element  102  from soft magnetic or nonmagnetic side shields  110 . The read element  102  is configured to read data from a magnetic media rotating below an air-bearing surface (represented by the x-y plane) of the transducer head  100 . In at least one implementation, the read element  102  is created through a NIL imprinting process. 
     The transducer head  100  also includes a barrier layer  114  between a coil  116  and the shield  108 . The coil  116  in combination with a write pole  118  receives a write signal from the processing electronics and changes the magnetic polarization of magnetic regions on an adjacent magnetic media (not shown), thereby writing the data from the write signal to the magnetic media. 
     To avoid the build-up of electro-static charge and certain electrical shock events, metal features  124  (which may also be referred to herein as “substrate electrical connections” or “electrical vias”) are embedded in the basecoat  104  to connect one or more contact pads (not shown) on the lower shield  106  to the substrate  103 . Forming such electrical connections  124  via one or more of the implementations disclosed herein may result in surface topography that is reduced as compared to existing methods. 
     The transducer head  100  is attached to an air-bearing slider (not shown) at a distal end of an actuator arm flexure (not shown). The slider enables the transducer head  100  to fly in close proximity above a corresponding surface of the adjacent magnetic media. The air-bearing surface of the transducer head  100  faces the magnetic media. The actuator arm flexure attached to a cantilevered actuator arm (not shown) and the actuator arm flexure is adjustable to follow one or more tracks of magnetic data on a magnetic media (not shown). Electrical wires (not shown) extend along the actuator arm flexure and attach to contact pads (not shown) on the slider that ultimately connect to the transducer head  100 . Read/write and other electrical signals pass to and from processing electronics (not shown) to the transducer head  100  via the electrical wires and contact pads. 
     Typically, multiple transducer heads that are the same or similar to the transducer head  100  are formed on a semi-conductor wafer at a factory and then separated by a dicing process. Therefore, multiple transducer heads may be formed simultaneously via the processes disclosed herein. One or multiple substrate electrical connections may be included in a single transducer head. 
     The steps discussed below with respect to  FIGS. 2-11  describe implementations of one or more methods for building substrate electrical connections in thin film transducer heads. Each of  FIGS. 2-11  shows a cross-section of a transducer head taken across the x-y plane of  FIG. 1 . 
       FIG. 2  illustrates a first example photoresist exposure and development step in creating substrate electrical connections in a transducer head  200 . A patterned photoresist  210  having recesses  220  and  222  formed therein is shown on top of a first basecoat layer  204 . The first basecoat layer  204  is above and in contact with a substrate  203 , which serves as a mounting surface for the transducer head  200 . 
     The first basecoat layer  204  is a nonmagnetic, nonconductive material such as Al 2 O 3  that is deposited on the substrate  203 . The first basecoat layer  204  has a height (y-direction) that is less than a desired final basecoat height for the transducer head  200 . In one implementation, the height of the first basecoat layer  204  deposited on the substrate  203  is between forty and eighty percent of a final basecoat thickness that is to be deposited on the transducer head. In another implementation, the height of the first basecoat layer  204  deposited on the substrate  203  is between forty and eighty percent of a final basecoat thickness prior to a planarization process. 
     The substrate  203  is a hard, thermally stable material such as AlTiC, which may be of considerably greater height than the first basecoat layer  204 . In one implementation, the substrate layer has a height of approximately 1210 μm, and the first basecoat layer  204  has a height that is approximately three microns. 
     The patterned photoresist  210  may be either a negative or positive photoresist and has two recesses (e.g., the recesses  220  and  222 ) formed therein. In one implementation, the y-direction height of the patterned photoresist  210  is between approximately two and eight microns. 
     To create the patterned photoresist  210 , a liquid photoresist layer is deposited substantially evenly across the transducer head  200 . A photomask (not shown) having a pattern corresponding to the recesses  220 ,  222  in the patterned photoresist  210  is positioned to mask portions of the liquid photoresist layer while the unmasked portions are exposed to a high intensity light. This exposure process changes the solubility of either exposed or unexposed portions of the photoresist layer, depending upon the type of photoresist utilized. After the exposure, portions of the photoresist are removed, such as by a developer solution. In one implementation, the developer solution is an organic highly basic solution. 
       FIG. 3  illustrates an example substrate-etching step in creating substrate electrical connections in a transducer head  300 . During the substrate-etching step, holes (e.g., a hole  324 ) are etched into a basecoat  304  to expose portions of a substrate  303 . The etching step may be either a wet or dry etch and may be performed while a patterned photoresist (such as the patterned photoresist  210  in  FIG. 2 ) is in place on the basecoat  304 , protecting portions of the transducer head that will not be etched. 
     After the etching, the patterned photoresist may be removed. In one implementation, the patterned photoresist is removed by a resist-strip that chemically alters the patterned photoresist so that it no longer adheres to the substrate. Alternatively, the photoresist may be removed by an ashing process. 
       FIG. 4  illustrates an example photoresist deposition step in creating substrate electrical connections in a transducer head  400 . The transducer head  400  has a basecoat  404  with holes (e.g., a hole  424 ) etched therein to expose an underlying substrate  403 . A layer of a liquid photoresist  430  is deposited substantially evenly across the transducer head  400  to coat the basecoat  404  and fill the etched holes, as shown in  FIG. 4 . 
       FIG. 5  illustrates another photoresist exposure and development step in creating substrate electrical connections in a transducer head  500 . The transducer head  500  has a basecoat  504  with a number of etched holes (e.g., an etched hole  524 ) therein, exposing an underlying substrate  503 . A patterned photoresist  530  is on top of and in contact with the basecoat  504 . 
     The patterned photoresist  530  is created by depositing a liquid photoresist layer evenly across the transducer head  500 . A photomask (not shown) having a pattern corresponding to the recesses  526 ,  528  in the patterned photoresist  530  is positioned to mask portions of the liquid photoresist layer. The masked photoresist layer is then exposed to a high intensity light to change the solubility of portions of the photoresist. The exposed portions of the photoresist are developed in an aqueous solution, leaving behind the patterned photoresist  530  with two recesses (e.g., the  526  and  528 ) therein. 
     The recesses  526  and  528  in the patterned photoresist  530  are each vertically aligned with an etched hole (e.g., holes  524  and  532 , respectively) in the basecoat  504 , such that each of the recesses  526  and  528  in the photoresist layer shares a common base with one of the etched holes  524  and  532  in the basecoat  504 . However, each of the recesses  526 ,  528  in the photoresist layer is wider than the width of the corresponding etched hole  524  and  532 , respectively, in the basecoat  504 . Therefore, metal may be plated into each of the etched holes  524  and  532  and expanded beyond the width of the respective etched holes  524  and  532 . Plating metal in this manner prevents voids from forming between the basecoat  504  and the metal (not shown) during the plating process. 
       FIG. 6  illustrates an example electroplating step in creating substrate electrical connections in a transducer head  600 . Prior to the electroplating step, a patterned photoresist (such as the patterned resist  530  illustrated atop the basecoat  504  in  FIG. 5 ) is formed on top of a basecoat  604  to protect portions of the transducer head  600  while metal (e.g., a metal connection  640 ) is plated into a number of etched holes in the basecoat  604  during the electroplating step. 
     In one implementation, a seed layer (not shown) is deposited on the transducer head  600  prior to the electroplating step to help the metal adhere to a substrate  603  and a basecoat  604 . In one implementation, this seed layer is approximately 0.2 μm thick. 
     After the metal is plated into the etched holes in the basecoat  604 , the patterned photoresist is removed, leaving behind metal connections (e.g., a metal connection  640 ) that are in contact with the substrate  603  and partially or fully embedded in the basecoat  604 . As viewed in the x-y cross-section of  FIG. 6 , each of the metal connections has a base portion (e.g., a base portion  636 ) and two protruding shoulders (e.g., shoulders  638  and  639 ) on either side of the base portion. This structure, including the base portion and the shoulders is referred to hereinafter as an “electrical recessed via.” 
     In at least one implementation, the shoulders  638  and  639  of the electrical recessed via are connected along the x-z plane. For instance, the shoulders  638  and  639  of the electrical recessed via  640  may be opposing sides of a cylindrical shell (i.e., a casing) that arcs into the x-z plane and extends longitudinally in the y-direction. Alternatively, the shoulders  638  and  639  may be opposing sides of a rectangular shell. 
     In the same or an alternate implementation, the base portion  636  illustrated in  FIG. 6  a cylindrical, rectangular, or any non-traditional shape that extends longitudinally in the y-direction and is circular, rectangular, etc. when viewed head-on in the x-z plane. 
     The metal used to form the electrical recessed vias is an electrically conductive metal, which may be a variety of materials including, without limitation, Cu and NiFe. The height of the base portion (e.g. the base portion  636 ) of each of the electrical recessed vias is substantially equal in height (y-direction) to the height of the basecoat  604 . The shoulders of each of the electrical recessed vias (e.g., the shoulders  638  and  639 ) are also substantially equal in height to the height of the basecoat  604 . 
       FIG. 7  illustrates an example feature-building step in creating substrate electrical connections in a transducer head  700 . During the feature building step, additional features, such as heaters (e.g., a heater  744 ), bleed resistors (not shown), or other electrostatic discharge devices are added to a basecoat  704  of the transducer head  700 . 
     In one implementation, a patterned photoresist (not shown) is formed on the transducer head  700  prior to the addition of such features. The patterned photoresist may be formed according to the same or similar processes as those discussed above with respect to  FIGS. 2 and 5 . After the additional features are added, the patterned photoresist is removed. 
     The additional features may be added through any number of processes including deposition and electroplating. 
       FIG. 8  illustrates another example photoresist exposure and development step in creating substrate electrical connections in a transducer head  800 . An x-y cross section of the transducer head  800  is shown. The cross section includes a substrate layer  803 , a basecoat  804 , and a number of electrical recessed vias (e.g., an electrical recessed via  840  having a base  836  and shoulders  838  and  839 ) formed therein. A patterned photoresist  842  is formed on the transducer head, and is sized and configured to allow for plating of additional metal within the recess (e.g., between the shoulders  838  and  839 ) of each of the electrical recessed vias. 
     In one implementation, the patterned photoresist  842  is created by a process the same or similar to those processes described with respect to the patterned photoresists in  FIGS. 2 and 5 . 
       FIG. 9  illustrates a second example electroplating step in creating substrate electrical connections in a transducer head  900 . During the second electroplating step, an interior metal prong (e.g., the interior metal prong  950 ) is plated on top of a base (e.g., a base  936 ) within an upper casing  952  of each of a number of electrical recessed vias formed on the transducer head  900 . In one implementation, the interior metal prong is plated in the center of the upper casing. In the same or an alternate implementation, the upper casing  952  is a hollow cylindrical shell that arcs into the x-z place and extends longitudinally away from the substrate  903  (y-direction). An x-y cross section of the upper casing  952  (as illustrated in  FIG. 9 ) includes two outer prongs or shoulders  938  and  939  on top of and on opposite sides of the base portion  936 . The interior prong  950  is plated on top of the base and within the upper casing (i.e., between the shoulders  938  and  939 ). 
     The metal used to form the interior metal prongs of the electrical vias is electrically conductive and may be of the same or a different material from that utilized to form the base and the upper casing of each of the electrical vias. A patterned photoresist (such as the patterned photoresist  842  illustrated in  FIG. 8 ) may be in place during the electroplating, and removed after such plating is complete. 
     The interior prong  950  has an x-direction cross-section that is less than an inner x-direction cross-section or diameter of the upper casing  952  (i.e., the spacing between the shoulders  938  and  939 ) so that the interior prong  950  does not contact an inner surface of the upper casing  952 . In one implementation, the y-direction height of the interior prong  950  is less than or substantially equal to the height of the upper casing  952 . In another implementation, the height of the interior prong  950  is greater than the upper casing  952 . 
       FIG. 10  illustrates an example additional basecoat layer application step in creating substrate electrical connections in a transducer head  1000 . A cross section of the transducer head  1000 , taken across the x-y plane, has a first layer of basecoat  1004  and a number of electrical vias (e.g., electrical vias  1040  and  1044 ) therein that are in contact with a substrate  1003  below the first basecoat layer  1004 . Each of the electrical vias has a lower, base portion (e.g., base portion  1036 ) and an upper, three-pronged portion (e.g., a three pronged portion  1052 ) in contact with the base portion and extending away from the base portion. 
     In the additional basecoat layer application step, a second layer of basecoat  1046  is deposited in a substantially even manner across the transducer head  1000 , creating a number of “humped” topographical features (e.g., the topographical features  1048 ) on the surface of the transducer head  1000 . In one implementation, the combined height of the first  1004  and second  1046  layers of basecoat is substantially equal to a total height of the electrical vias. For example, the combined height (y-direction) of the first  1004  and second  1046  layers of basecoat may be substantially equal to the distance between the bottom of base portion  1036  to the top of the tallest prong  1038  of the electrical vias. 
     The topographical features created on the transducer head  1000  incident to the addition of the second layer  1046  of basecoat may extend away from the substrate  1003  in the y-direction beyond each of the electrical vias by a height that is substantially equal to the second layer  1046  of basecoat. In other implementations, the second layer of basecoat  1046  may have a height that is shorter or greater than any or all the prongs of the electrical vias. 
     The first  1004  and second  1046  layers of the basecoat are deposited separately, with one or more metal plating processes performed in between to form the electrical vias. In one implementation, the layer of basecoat  1004  has a thickness that is 40 to 80 percent of the combined thickness of both the first  1004  and second  1046  layers of basecoat either before or after planarization of the transducer head. As a result, the topographical features created incident to the deposition and plating processes are reduced in height as compared to the height of topographical features that may result when the basecoat is applied in a single step. Specifically, such topographical features may be reduced by 40 to 80%. 
     Moreover, the topographical features (e.g., the topographical features  1048 ) are small enough that the transducer head  1000  can be planarized, such as along the dotted line  1050 , without creating a significant variability in a total basecoat height (e.g., the y-direction height of the combined first  1004  and second  1046  layers of basecoat). The planarization may be performed, for example, by a milling or lapping process. 
     After the planarization of the transducer head  1000 , each of the electrical vias  1040  and  1044  may be exposed to allow for contact with one or more contact pads on a lower shield (not shown) of the transducer head  1000 . 
       FIG. 11  illustrates an example contact pad connection step in creating substrate electrical connections in a transducer head  1100 . A cross section of the transducer head  1100 , taken across the x-y plane, has a first layer of basecoat  1104 , a second layer of basecoat  1146 , and a number of electrical vias (e.g., electrical vias  1140  and  1144 ) therein that are in contact with a substrate  1103  below the first basecoat layer  1104 . Each of the electrical vias has a base portion (e.g., base portion  1136 ) and an upper portion (e.g., an upper portion  1152 ). 
     The upper portion  1152  includes an outer casing or shell (illustrated by outer prongs  1172  and  1174  in the cross-sectional view of  FIG. 6 ) that may be a cylindrical, rectangular, or non-traditional shape. In one implementation, the upper portion  1152  is a cylindrical shell that arcs into the x-z place and extends longitudinally away from the substrate  1103  (y-direction). The upper portion  1152  also includes an interior prong (e.g., an interior prong  1170 ) within the outer casing. Both the outer casing (illustrated by opposing sides  1172  and  1174  of the outer casing) and the interior prong  1170  are in contact with the base portion  1176 . The interior prong  1170  may be round, oval, rectangular, or any other non-traditional shape when viewed head-on in the x-z plane. In the same or an alternate implementation, the base portion  1136  of the electrical via is circular, rectangular, or any non-traditional shape when viewed head-on in the x-z plane. 
     The upper portion  1152  is axially aligned with the base portion  1136  along an axis  1164 . As used herein, the term “axially aligned” refers to an alignment perpendicular to the substrate layer  1103  (e.g., a y-direction alignment) along an axis  1164  between two or more structures that each physically intersect the axis  1164 . In one implementation, the axis  1164  intersects a center of the base portion  1136 . 
     A contact pad (e.g., a contact pad  1160 ) is arranged on top of each of the electrical vias such that it is axially aligned with the upper portion (e.g., an upper portion  1152 ) and the base portion (e.g., the base portion  1136 ) along the axis  1164  of the electrical via. In one implementation, the contact pad  1160  and the interior prong  1170  are axially aligned with a center of the base portion  1136 . 
     In the implementation illustrated by  FIG. 11 , the upper portion  1152  of the electrical via  1140  has a width (e.g., an x-direction edge-to-edge cross section  1166 ) that is greater than a width (e.g., an x-direction edge-to-edge cross section  1168 ) of the base portion  1136 . 
     The contact pad  1160  is in contact with both the interior prong  1170  and the outer casing (illustrated by opposing sides  1172  and  1174  of the outer casing) of the upper portion of the electrical via  1140 . In one implementation, electricity may readily flow through each of the contact pads  1160 ,  1162  through the corresponding electrical vias  1140  and  1144 . 
     In one implementation, the contact pad  1162  is formed by depositing a seed layer (not shown) on the transducer head  1100  to help the contact pad  1162  adhere to the transducer head  1100 . A patterned photoresist (not shown) is created on the transducer head  1100  with a recess patterned therein to receive the contact pad  1162 . Metal material is then electroplated into the recess to form the contact pad  1162  and the patterned resist is removed. The surface of the transducer head  1100  may thereafter be dry-etched to remove the seed layer and a top portion of the contact pad. 
       FIG. 12  illustrates a flow-chart of example operations for creating substrate electrical connections of a transducer head that result in a reduced surface topography. A basecoat etching operation  1205  etches holes in a first layer of a basecoat on a substrate. The first layer basecoat may be a nonmagnetic, non-conductive material such as Al 2 O 3 , and the substrate wafer is preferably a hard, thermally stable material such as AlTiC. In one implementation, the first layer of the basecoat has a thickness that is 40 to 80 percent of a desired final basecoat thickness. In the same or a different implementation, the final desired basecoat thickness is between 3 and 7 microns. 
     Several precursor steps may be employed to etch the holes in the first layer of the basecoat. First, recesses are patterned into a photoresist layer deposited on the substrate. A layer of liquid photoresist, which may be a negative or positive photoresist, is deposited across the top of the basecoat and a patterned photomask is positioned to mask the photoresist. While masked, the layer of liquid photoresist is exposed to a high intensity light to change the solubility of either the exposed or the unexposed portions of the liquid photoresist, depending on the type of photoresist utilized. The modified portions of the resist are thereafter removed by a developer solution, which may be, for example, an organic highly basic solution. In an implementation where a positive resist is used, the exposed portions of the resist have their solubility modified during the exposure. Here, the developer solution is applied to dissolve the exposed portions of the resist so that the unexposed portions remain on the wafer. 
     After the photoresist is patterned, holes are etched into the basecoat via an etching process, which may be either wet or dry. Thereafter, the patterned photoresist is stripped away from the basecoat, such as by using a resist strip. 
     The etched holes each have a depth substantially equal to the depth of the basecoat so that the underlying substrate is exposed at the base of each of the etched holes. The width of the etched holes may vary, but in one implementation, the width is substantially between 2 and 50 microns. 
     A building operation  1210  plates metal into each of the etched holes in the basecoat. The building operation  1210  includes several precursor steps. First, a thin seed layer is deposited across the of the transducer head. The seed layer may be any one of a number of metals having properties to help the metal adhere to the substrate and basecoat. For example, the seed layer may be Cu, NiFe, CoFe, CoNiFe, CoPt, Cr, Ru, Ta, Pt, or Au. In one implementation, the seed layer is approximately 0.2 μm thick. 
     After the seed layer is deposited, another photoresist layer is deposited onto the seed layer to be patterned prior to the metal plating process. Again, a photomask is positioned to mask portions of the photoresist during an exposure to high intensity light. After the exposure, portions of the resist are removed. This process creates a patterned photoresist that has a number of recesses corresponding to each of the etched holes in the basecoat. Each of the recesses in the patterned photoresist is vertically aligned with one of the etched holes in the first layer of basecoat. However, the width of each of the recesses in the photoresist may greater than the width of the corresponding etched hole to allow for metal to be plated beyond the width of each of the etched holes in the basecoat. 
     An electrically conductive metal, such as NiFe or Cu, is then plated into each of the etched holes in the basecoat and expanded beyond the width of the etched hole to prevent voids from forming between the first layer of basecoat and each of the metal connections. This process creates a number of electrical recessed vias, where each electrical recessed via includes a base portion nested within one of the etched holes in the basecoat and an upper casing. In one implementation, the upper casing is a hollow cylindrical shell. In another implementation, the upper casing has a diameter or width that is greater than a diameter or width of the underlying base portion. In yet another implementation, the upper casing has a longitudinal height that is substantially equal to the height of the first layer of the basecoat. After the building operation  1210 , the patterned photoresist is removed. 
     Another feature building operation  1215  constructs ancillary features on the first basecoat layer to be embedded in the transducer head. During the building operation, another patterned photoresist may be used to protect portions of the transducer head. After the additional features are added, this layer of photoresist may be removed. 
     In one implementation, the feature building operation  1215  forms one or more heaters on the first basecoat layer. In operation, such heaters can be turned on to adjust a fly height of the transducer head above a rotating media disk by thermally expanding the basecoat. In the same or an alternate implementation, the feature building operation  1215  may attach one or more electrostatic discharge (ESD) devices to the basecoat, such as a bleed resistor. 
     Another building operation  1220  plates a second metal layer inside of the upper casing of each electrical via and above the base portion such that a metal prong is added on top of the base portion and interior to the upper casing. In one implementation, the metal prong is sized such that it does not contact an inner sidewall of the upper casing. The metal prong and upper casing may also be collectively referred to herein as the “upper portion.” During the building operation  1220 , portions of the transducer head may again be protected by patterned photoresist. 
     The metal utilized for building operation  1220  is electrically conductive and may be the same material as utilized in the metal plated by building operation  1210 . However, in at least one implementation, the metal plated by building operation  1220  is a different material than that applied in building operation  1210 . 
     In one implementation, the height of the metal prong above the base portion in each of the electrical vias is less than or equal to the height of the first layer of the basecoat. In the same or a different implementation, the height of the metal prong in each of the electrical vias is less than or equal to a height of the upper casing. 
     A basecoat application step  1225  applies a second layer of basecoat to the transducer head, filling the potential void between the shoulders of the first metal layer and the base of the second metal layer with the basecoat material. 
     A planarization step  1230  planarizes the surface of the transducer head, removing portions of the electrical vias and/or of the second layer of basecoat. Additionally, the planarization step  1230  exposes an upper edge of the upper portion on the surface of the wafer such that the upper casing and the interior prong may contact one or more contact pads on an above structure, such as a bottom shield. The planarization step  1230  may be performed by a lapping, polishing, milling or electric-chemical planarization (eCMP) operation. 
     In one implementation, significant surface topography is removed from the transducer head during the planarization step  1230 . In the same or an alternate implementation, substantially less than two microns of topography remain on the transducer head after the planarization step  1230 . In yet another implementation, a few nanometers of topography remain on the transducer head after the planarization step  1230 . In any or all of these implementations, the transducer head may be suitable for NIL patterning without polishing. The first basecoat layer may have a height that is 40-80% of the combined height of the first and second layers of basecoat after the planarization step  1230 . 
     In another example implementation, the height of the first basecoat layer is substantially equal to three microns and the height of the second basecoat layer is substantially equal to two and a half microns prior to the planarization step  1230 . Therefore, two and a half microns of topography are formed on top of the electrical vias by the basecoat application step  1225 . In this case, the planarization step  1230  may remove at least two and a half microns of material from the wafer to expose the upper portion of the electrical recessed vias. 
     After the planarization step  1230 , a contact pad attachment step  1235  attaches a contact pad to the transducer head to be in contact with the upper portion of each of the electrical vias. In one implementation, the contact pad contacts the upper perimeter of the outer casing and the interior prong within the outer casing. 
     In another implementation, the contact pad is axially aligned with the upper portion and base portion. In yet another implementation, the contact pad is axially aligned with the interior prong and a center of the base portion. 
     The specific steps discussed with respect to each of the implementations disclosed herein are a matter of choice and may depend on the materials utilized and/or the topography-related requirements of a given system. The steps discussed may be performed in any order, adding and omitting as desired, unless explicitly claimed otherwise or a specific order is inherently necessitated by the claim language. 
     The above specification, examples, and data provide a complete description of the structure and use of exemplary implementations of the invention. Since many implementations of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.