Abstract:
Methods and structures for the fabrication of perpendicular thin film heads are disclosed. Prior to the deposition of shield structures, seed layers having anti-reflective properties are utilized, eliminating the need to deposit, then remove, traditional inorganic anti-reflection coatings prior to shield plating.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to structures and methods for fabricating perpendicular write heads. More specifically, the invention relates to structures and methods for fabricating wrap around and trailing shields using seed layers with anti-reflective properties prior to shield deposition. 
     2. Description of the Related Art 
     Perpendicular write heads are currently well known in the art. Variants of such heads, having wrap around shields and trailing shields, have been recently disclosed. See, for example US Patent Application Publications 2005/0259355, 2006/0044682 and 2006/0174474, assigned to Hitachi Global Storage Technologies, Netherlands B.V. 
     During the fabrication of the wrap around shield of the prior art, a film stack containing the magnetic pole material, a non-magnetic gap layer, a CMP stop layer, and a number of image transfer layers are deposited. After the pole width is imaged and the film stack etched by a number of consecutive etch processes, a film stack containing the tapered pole material is created. A conformal non-magnetic layer is then deposited, which will serve as the side shield or wrap around shield gap material. Following deposition of the side gap material, a layer of RI-etch-able (or RIE-able, reactive ion etch-able) material is deposited and the structure planarized by CMP. Following planarization, the RI-etch-able material is removed leaving the tapered pole, main gap and side gap materials. A magnetic material is then deposited over this structure by electroplating to form the wrap around shield. Prior to plating, a conductive seed layer is deposited to provide a starting cathode for the plating process. Subsequent to seed layer deposition, a blanket photo resist layer is deposited. This layer is imaged and developed to provide a plating mask for the shield. A non conductive anti-reflective SiO x N y  coating is usually deposited over the seed layer prior to photo resist deposition to minimize reflective notching during exposure of the photo resist, which must be removed prior to electroplating. Removal of this coating can be difficult due to the complex geometries of the tapered pole, and if not completely removed shield plating integrity will be compromised. 
     During the formation of trailing shields of the prior art, a film stack containing the magnetic pole material, a non-magnetic gap layer, a CMP stop layer, and a number of image transfer layers are deposited. The pole width is imaged and the film stack etched by a number of consecutive etch processes, creating a film stack containing the tapered pole material. A filler layer is deposited and the resulting structure planarized by CMP to the stop layer. A plating seed layer is subsequently deposited, followed by deposition of an anti-reflective SiO x N y  coating. As with wrap around shields, the anti-reflective coating must be removed prior to shield plating. Eliminating the need for a separate anti-reflective coating reduces process steps, reducing costs and increasing throughput. 
     What is needed is a better process for producing the wrap around and trailing shields for the perpendicular write head. 
     United States Patent Application Publication 2006/0174474 discloses a mask structure for fabricating a write pole for a perpendicular write head. The mask structure includes a first and second hard mask structures separated by an image transfer layer, such as DURIMIDE. The first mask structure may be a bi-layer mask structure that functions as a CMP stop as well as a hard mask for ion milling. The first hard mask is chosen to have a desired resistance to removal by ion milling to maintain excellent track width control during an ion milling process used to form the write pole. Therefore, the first hard mask may be comprises of two layers selected from the group consisting of Rh, alumina, and diamond like carbon (DLC). The second hard mask is constructed of a material that functions as a bottom antireflective coating as well as a hard mask. 
     United States Patent Application Publication 2006/0044682 discloses a write element for use in perpendicular magnetic recording. The write element including a write pole and a self aligned wrap around shield that can have a trailing shield gap thickness that is different from its side shield gap thickness. The materials making up the trailing shield gap and the side shield gaps can be different materials or can be the same material deposited in two different steps. The side or wrap around portions of the trailing shield can extend down to the level of the leading edge of the write pole or can terminate at some point between the levels of the leading and trailing edge to form a partial wrap around trailing shield. 
     United States Patent Application Publication 2005/0239001 discloses methods of forming a component of a thin film magnetic head and improving the plating of a component of a thin film magnetic head. The methods include the use of a high activation energy chemically amplified photoresist (CARS) that is contacted with a low pH high saturation magnetic moment plating solution to form a magnetic head component that is essentially free of plating defects. The methods find utility in hard disk drive applications, such as in the manufacture of magnetic poles for the write head of a hard disk drive. 
     United States Patent Application Publication 2005/0259355 discloses a perpendicular write head including a main pole and a trailing shield, the main pole being made of a diamond-like carbon (DLC) layer as hard mask and a rhodium (Rh) layer as shield gap, both DLC and Rh layers being CMP stop layers so as to avoid corner rounding and damage from chemical mechanical planarization (CMP) process, the DLC layer being removed by reactive ion etching (RIE) to create a trench, the trailing shield being deposited into the trench for self alignment. 
     United States Patent Application Publication 2005/0068671 discloses a magnetic transducer with separated read and write heads for perpendicular recording. The write head has a trailing shield that extends from the return pole piece toward the main pole piece to form the write gap at the air-bearing surface. One embodiment of the trailing shield is a two part structure with a pedestal and a much smaller tip that confronts the main pole piece at the gap. In one embodiment a sink of non-magnetic, electrically conductive material is disposed in the separation gap between the read head and the flux bearing pole piece. The sink is preferably made of copper and does not extend to the ABS. 
     United States Patent Application Publication 2004/0264066 discloses at both end portions of at least a soft magnetic layer of a magneto-resistive effect film, a pair of bias magnetic field applying layers are disposed for applying a longitudinal bias magnetic field to the soft magnetic layer via magnetic underlayers. Further, mutual lattice point-to-point distances in the plane where each magnetic underlayer and the corresponding bias magnetic field applying layer are mated, are substantially equalized to each other. Therefore, a coercive force Hc in an in-plane direction (direction parallel to a film surface) of each bias magnetic field applying layer can be maintained at a high level so that even when further gap narrowing or track narrowing is aimed, the bias magnetic field applying layers can act to apply an effective bias magnetic field, i.e. can act to suppress occurrence of the Barkhausen noise. 
     U.S. Pat. No. 7,097,923 discloses a tri-layer anti-reflective coating for use in photolithographic applications, and specifically, for use in ultraviolet photolithographic processes. The tri-layered anti-reflective coating is used to minimize pattern distortion due to reflections from neighboring features in the construction of microcircuits. The tri-layer anti-reflection coating features a first layer, a first dielectric layer, an absorption layer disposed on the first dielectric layer, and a second dielectric layer, which is then disposed between the absorption layer and a photoresist layer. At least the absorption layer and dielectric layers can be formed using vacuum deposition. A unique character of the tri-layer anti-reflective coatings is that it dampens reflections structures having severe topologies and also allows a thinner anti-reflection layer that has a wider process latitude. 
     U.S. Pat. No. 6,912,106 discloses a method and system for providing a recording head is disclosed. The method and system include providing a first pole, a second pole, a write gap and at least one coil. The write cap separates the first pole from the second pole. The coil(s) include a plurality of turns and is between the first and second poles. The first pole includes a pedestal that has a first portion and a second portion. The first portion includes a high moment electroplated material. The second portion includes a hot seed layer that has a high moment sputtered material. The second portion of the first pole is adjacent to the write gap. 
     U.S. Pat. No. 6,876,507 discloses a thin-film write head employing pole pieces formed of an electroplated body-centered cubic (BCC) nickel-iron alloy with a saturation flux density (B S ) of 1.9 to 2.3 T (19 to 23 kG) and an acceptable coercivity (H C ) of about 80 to about 160 A/m (1-2 Oe). The iron content of the electroplated nickel-iron alloy is from 64% to 81% by weight. The two-layer pole fabrication process holds magnetic anisotropy and coercivity to useable values while improving saturation flux density and optimizing magnetostriction. This is accomplished by first electroplating a BCC nickel-iron layer onto an underlying seed layer and then annealing the two layers to reduce coercivity to less than about 160 amps/meter and raise magnetization to acceptable levels. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a method for making a perpendicular head including fashioning a pole structure on a surface of a substrate, the pole structure having a tapered pole section in contact with the substrate, and a gap layer deposited on the tapered pole section. The method further includes depositing a conductive seed layer on the gap layer, the conductive seed layer having a reflectivity below 10% after deposition on the gap layer. 
     It is another object of the present invention to provide a method for making a perpendicular write head having a wrap around shield including fashioning a pole structure on a surface of a substrate, the pole structure having a tapered pole section in contact with the substrate, and a gap layer deposited on the tapered pole section. The method further includes depositing a conductive seed layer on the gap layer, the conductive seed layer having a reflectivity below 10%, after deposition on the gap layer and, depositing a wrap around shield on the conductive seed layer. 
     It is yet another object of the present invention to provide a method for making a perpendicular write head having a trailing shield including fashioning a pole structure on a surface of a substrate, the pole structure having a tapered pole section in contact with the substrate, and a gap layer deposited on the tapered pole section. The method further includes depositing a conductive seed layer on the gap layer, the conductive seed layer having a reflectivity below 10%, after deposition on the gap layer and, depositing a trailing shield on the conductive seed layer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be better understood when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings, wherein: 
         FIG. 1  is a partial cross sectional view looking into the air bearing surface (ABS) of a blanket deposited film stack prior to fabrication of a perpendicular write head with a wrap around shield, in accordance with an embodiment of the present invention; 
         FIG. 2  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure following the imaging and development of photo-resist layer  102 , during fabrication of a perpendicular write head with a wrap around shield, in accordance with an embodiment of the present invention; 
         FIG. 3  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure subsequent to the transfer of patterned feature  102 ′ into layers  106  and  108 , during fabrication of a perpendicular write head with a wrap around shield, in accordance with an embodiment of the present invention; 
         FIG. 4  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure subsequent to etching and ion milling to form the pole structure, during fabrication of a perpendicular write head with a wrap around shield, in accordance with an embodiment of the present invention; 
         FIG. 5  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure subsequent to deposition of side gap layer  502 , during fabrication of a perpendicular write head with a wrap around shield, in accordance with an embodiment of the present invention; 
         FIG. 6  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure subsequent to deposition of dielectric layer  602 , during fabrication of a perpendicular write head with a wrap around shield, in accordance with an embodiment of the present invention; 
         FIG. 7  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure subsequent to planarization by CMP, during fabrication of a perpendicular write head with a wrap around shield, in accordance with an embodiment of the present invention; 
         FIG. 8  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure subsequent to the removal of layers  602  and  109 ′, during fabrication of a perpendicular write head with a wrap around shield, in accordance with an embodiment of the present invention; 
         FIG. 9   a  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure subsequent to the deposition of seed layer  902 , during fabrication of a perpendicular write head with a wrap around shield, in accordance with an embodiment of the present invention; 
         FIG. 9   b  is a partial cross sectional view of detail  904  of  FIG. 9   a , for seed layers having a optional capping layer, in accordance with an embodiment of the present invention; 
         FIG. 9   c  is a chart of seed layer reflectivity at 248 nm, as a function of layer  110 ′ thickness and seed layer thickness, in accordance with an embodiment of the present invention; 
         FIG. 9   d  is a chart of seed layer  902   b  thickness versus layer  110 ′ thickness for a given seed layer reflectivity at 248 nm, in accordance with an embodiment of the present invention; 
         FIG. 9   e  is a chart of seed layer  902   b  thickness versus layer  110 ′ thickness for a given seed layer reflectivity at 193 nm, in accordance with an embodiment of the present invention; 
         FIG. 10  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure subsequent to the deposition of photo resist layer  1002 , during fabrication of a perpendicular write head with a wrap around shield, in accordance with an embodiment of the present invention; 
         FIG. 11  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure subsequent to the imaging and development of photo resist layer  1002 , during fabrication of a perpendicular write head with a wrap around shield, in accordance with an embodiment of the present invention; 
         FIG. 12  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure subsequent to the deposition of shield layer  1202 , during fabrication of a perpendicular write head with a wrap around shield, in accordance with an embodiment of the present invention; 
         FIG. 13  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure subsequent to the removal of photo resist layer  1002 , during fabrication of a perpendicular write head with a wrap around shield, in accordance with an embodiment of the present invention; 
         FIG. 14  is a schematic block diagram of the process for fabricating a wrap around trailing shield, in accordance with an embodiment of the present invention; 
         FIG. 15   a  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure subsequent to the deposition of seed layer  1502 , during fabrication of a perpendicular write head with a trailing shield, in accordance with an alternate embodiment of the present invention; 
         FIG. 15   b  is a partial cross sectional view of detail  1504  of  FIG. 15   a , for seed layers having a optional capping layer, in accordance with an alternate embodiment of the present invention; and, 
         FIG. 16  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure subsequent to the deposition of trailing shield  1602 , in accordance with an alternate embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The features and description of one embodiment the present invention are best understood while viewing the cross sectional structure views ( FIGS. 1-13 ) in light of the process block diagram  FIG. 14 . An alternate embodiment of the present invention is disclosed in  FIGS. 15-16 . 
       FIG. 14  is a schematic block diagram of the process for fabricating a wrap around shield, in accordance with an embodiment of the present invention. The process begins at step  1402 , wherein the layer stack  100  of  FIG. 1  is deposited.  FIG. 1  is a partial cross sectional view looking into the air bearing surface (ABS) of a blanket deposited film stack  100  prior to fabrication of a perpendicular write head with a wrap around shield. The film stack comprises blanket layers  102 - 112  deposited on substrate  114 , which is typically alumina (at the air bearing surface), but may be other materials such as magnetic pole shaping layers deeper (further from the ABS) into the structure. For the purposes of this disclosure, substrate  114  can be a bulk material on which all subsequent layers are deposited, or it can be a layer deposited over previously deposited under-layers. For example, when fabricating a combined read and write head structure, the latter is usually the case, as the read head structure is generally deposited first (not shown). Layer  112  makes up the magnetic pole material, and is typically a laminated, multilayer structure comprising layers of magnetic and non-magnetic materials. Above pole layer  112  is gap layer  110 , comprised of alumina or other non-magnetic materials. Preferably, alumina is used. Above gap layer  110  is CMP stop layer  109 . Typically, DLC (diamond like carbon) is used for this layer. A spacer layer  108  is deposited above DLC layer  109 , and is comprised of Durimide. Above spacer layer  108 , layers  102 ,  104 , and  106  are deposited. Layer  102  comprises the imaging photo resist layer that defines the width and location of the write pole. Layers  104  and  106  aid in transferring the developed features of photo resist layer  102  to the spacer layer  108 . Layer  106  is typically comprised of silica, and layer  104  is typically comprised of Durimide. 
     In step  1404  of  FIG. 14 , photo resist layer  102  is imaged and developed, creating feature  102 ′ in  FIG. 2 .  FIG. 2  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure  200  following the imaging and development of photo-resist layer  102 . 
     In step  1406  of  FIG. 14 , photo resist feature  102 ′ is transferred to layers  106  and  108 , creating features  106 ′ and  108 ′.  FIG. 3  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure  300  subsequent to the transfer of patterned feature  102 ′ into layers  106  and  108 . The transfer is carried out with three consecutive RIE process steps comprising a first oxidation step to etch layer  104 , a second fluorine etch step to etch silica layer  106 , followed by a third oxidation step to etch spacer layer  108 . Details of the RIE processes are well known to those skilled in the art. During the oxidation steps, photo resist layer  102  is removed, resulting in structure  300 . 
     In step  1408  of  FIG. 14 , the structure of  FIG. 3  is etched and ion milled to form the pole structure comprising features  108 ′,  109 ′,  110 ′, and  112 ′.  FIG. 4  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure  400  subsequent to etching and ion milling to form the pole structure. The width of the pole structure ( 108 ′,  109 ′  110 ′,  112 ′) is W p    402 . Details of the formation of the tapered pole section  112 ′ have been previously disclosed in the prior art and are well known. 
     In step  1410  of  FIG. 14 , side gap layer  502  is deposited around pole structure  108 ′,  109 ′,  110 ′,  112 ′.  FIG. 5  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure  500  subsequent to deposition of side gap layer  502 , in accordance with an embodiment of the present invention. Layer  502  typically comprises alumina, and is deposited by process that produces conformal coverage of the tapered pole structure. One such process is ALD (atomic layer deposition), but a number of other processes known to those skilled in the art are also suitable. 
     In step  1412  of  FIG. 14 , dielectric layer  602  is deposited.  FIG. 6  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure  600  subsequent to deposition of dielectric layer  602  in accordance with an embodiment of the present invention. Layer  602  typically comprises RIE-able (reactive ion etch-able) materials such as SiO 2 , Ta 2 O 5 , or Si x N y . 
     In step  1414  of  FIG. 14 , structure  600  is planarized by CMP.  FIG. 7  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure  700  subsequent to planarization by CMP in accordance with an embodiment of the present invention. Planarization is slowed or terminated by DLC stop layer  109 ′. 
     In step  1416  of  FIG. 14 , layers  602  and  109 ′ are removed by RIE processes.  FIG. 8  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure  800  subsequent to the removal of layers  602  and  109 ′, in accordance with an embodiment of the present invention. Layer  109 ′ is removed by an oxidation based RIE process suitable for the removal of DLC layers, whereas layer  602  is removed by conventional RIE processes well known to those skilled in the art. 
     In step  1418  of  FIG. 14 , seed layer  902  is deposited over structure  800 .  FIG. 9   a  is a partial cross sectional view looking into the air bearing surface (ABS) of the film structure  900  subsequent to the deposition of seed layer  902 , in accordance with an embodiment of the present invention. Seed layer  902  serves as conductive cathode layer for the subsequent deposition of the wrap around shield, which is usually deposited by electroplating. Prior to electroplating the shield, portions of the surface covered by seed layer  902  need to be masked to define the locations to which the shield will be confined. The masking is performed by a photo resist layer, which must be exposed and developed to create the mask. During exposure, reflective notching may occur in regions over the pole structure above gap layer  110 ′, which will create false, unwanted patterns when the resist is developed. In processes of the prior art, an inorganic SiO x N y , anti-reflective coating is deposited above seed layer  902  to prevent reflective notching. Since this coating is non-conductive, it must be removed via an RIE process prior electroplating of the shield structure. Since RIE is basically a “line of sight” process, removing the anti-reflective near the base of the tapered pole is difficult, and patches of anti-reflective coating may remain over the seed layer. During the subsequent electroplating step, these patches may not have metal deposited over them, or the metal plate may contain voids or be poorly adherent in these regions. It is a main advantage of embodiments of the present invention to eliminate the need for a separate anti-reflective coating by providing a seed layer with anti-reflective properties, which can serve the dual purpose of suppressing the reflective notching during photo resist exposure, while also being conductive enough to provide an effective cathode for shield electroplating. The seed layer should also provide good adhesion to both the photo resist and the shield materials. An added advantage of embodiments of the present invention is the elimination of two process steps, specifically the deposition and removal of the ARC (anti-reflective coating). 
     The anti-reflective properties of seed layer  902  are determined by the combined material compositions and thickness of both the seed layer  902  and the gap layer  110 ′, as well as the wavelength of light used for the photo resist exposure. Gap layer  110 ′ should be comprised of a dielectric material to impart the necessary anti-reflective properties to the conductive seed layer  902 . Preferably, the dielectric material for layer  110 ′ is alumina (Al 2 O 3 ), but may also be SiO 2 . Seed layer  902  is comprised of a noble metal, chosen from among the group Rh, Ir, and Ru. Preferably, Rh is used. An optional capping layer may be deposited over the noble metal seed layer to improve adhesion to the photo resist.  FIG. 9   b  is a partial cross sectional view of detail  904  of  FIG. 9   a , for seed layers having a optional capping layer, in accordance with an embodiment of the present invention. Capping layer  902   a , if used, is preferably less than about 5 nm and is comprised of Ru or CoFe. Design considerations limit the combined thickness of the non-magnetic portions of seed layer  902  and gap layer  110 ′ to a maximum of about 50 nm, for proper operation of the perpendicular head. Design considerations for proper plating of the wrap around shield limit the seed layer  902  to a minimum thickness of about 10-20 nm. These design considerations are relevant, because the reflectivity R of the seed layer  902  is dependent on both the thickness of gap layer  110 ′ and seed layer  902  in accordance with the present invention. A seed layer having suitable anti-reflective properties should have a reflectivity R less than about 10%, preferably less than 5%, at the wavelength of light the photo resist is exposed. For the photo resists in common usage, two wavelengths of light are of interest, 248 nm and 193 nm. 
     For example,  FIG. 9   c  is a chart  906  of seed layer reflectivity at 248 nm, as a function of layer  110 ′ thickness and seed layer thickness, in accordance with an embodiment of the present invention. In this plot, the reflectivity R (in %) of a seed layer  902  comprising a capping layer  902   a  of 2 nm Ru over a base seed layer  902   b  of Rh of various thickness, is shown as a function of alumina gap layer  110 ′ thickness. Curves  910 ,  912 ,  914 ,  918 , and  920  correspond to a Rh thickness of 16, 14, 12, 10, and 8 nm, respectively. All curves  910 - 920  show a minimum in reflectivity for an alumina gap layer thickness of about 30-32 nm. The curves also show a monotonic decrease in reflectivity as gap layer  110 ′ increases in thickness from about 20 nm to about 30-32 nm. Reflectivity increases again as gap layer  110 ′ increases in thickness above about 30-32 nm. At any given gap layer thickness, reflectivity decreases as the Rh base seed layer  902   b  thickness decreases. For reflectivity values less than 10%,  FIG. 9   c  shows that the Rh base seed layer  902   b  should be below about 16 nm in thickness, and that all values of layer  110 ′ thickness from 20 nm to 35 nm are suitable if the Rh base seed layer  902   b  thickness is below about 10 nm. 
       FIG. 9   d  is a chart  930  of Rh seed layer  902   b  thickness versus gap layer  110 ′ thickness for a given seed layer reflectivity at 248 nm, in accordance with an embodiment of the present invention. This is the same data shown in  FIG. 9   c . Curve  932  represents the locus of values corresponding to a reflectivity R of 10%. Curve  934  represents the locus of values corresponding to a reflectivity R of 5%. The area under curve  932  represents acceptable values of seed layer thickness and gap layer thickness resulting in a reflectivity R less than 10%. The shaded area under curve  934  represents preferred values of seed layer thickness and gap layer thickness resulting in a reflectivity R less than 5%. It is useful to note that all values under curve  932  meet the basic design criteria for a seed layer cited above, i.e. a seed layer  902  greater than 10 nm in thickness, and a gap layer+seed layer thickness less than 50 nm. 
     In another example,  FIG. 9   e  is a chart  940  of seed layer  902   b  thickness versus alumina layer  110 ′ thickness for a given seed layer reflectivity at 193 nm, in accordance with an embodiment of the present invention. Curve  942  represents the locus of values corresponding to a reflectivity R of 10% for a Rh seed layer  902   b  having a 2 nm capping layer  902   a  of Ru. Curve  944  represents the locus of values corresponding to a reflectivity R of 5%. The area under curve  942  represents acceptable values of seed layer thickness and gap layer thickness resulting in a reflectivity R less than 10%. The shaded area under curve  944  represents preferred values of seed layer thickness and gap layer thickness resulting in a reflectivity R less than 5%. For the shorter wavelength of 193 nm, the suitable alumina gap layer  110 ′ thickness range is reduced to about 10-27 nm. 
     Returning to  FIG. 14 , in step  1420  a blanket photo resist is deposited over anti-reflective seed layer  902 .  FIG. 10  is a partial cross sectional view  1000  looking into the air bearing surface (ABS) of the film structure subsequent to the deposition of photo resist layer  1002 , during fabrication of a perpendicular write head with a wrap around shield, in accordance with an embodiment of the present invention. 
     In step  1422  of  FIG. 14 , photo resist layer  1002  is imaged and developed in accordance with methods well known to those skilled in the art.  FIG. 11  is a partial cross sectional view  1100  looking into the air bearing surface (ABS) of the film structure subsequent to the imaging and development of photo resist layer  1002 , during fabrication of a perpendicular write head with a wrap around shield, in accordance with an embodiment of the present invention. 
     In step  1424  of  FIG. 14 , the wrap around shield is deposited over seed layer  902  via electroplating, a process well known to those skilled in the art.  FIG. 12  is a partial cross sectional view  1200  looking into the air bearing surface (ABS) of the film structure subsequent to the deposition of shield layer  1202 , during fabrication of a perpendicular write head with a wrap around shield, in accordance with an embodiment of the present invention. 
     In step  1426  of  FIG. 14 , the photo resist layer  1002  is removed by methods well known to skilled in the art.  FIG. 13  is a partial cross sectional view  1300  looking into the air bearing surface (ABS) of the film structure subsequent to the removal of photo resist layer  1002 , during fabrication of a perpendicular write head with a wrap around shield, in accordance with an embodiment of the present invention. 
     The forgoing discussion has been focused upon the process for making a perpendicular write head having a wrap around shield. However, the suitability and application of anti-reflective seed layers is not limited only to the production of wrap around shields, but may be applied to perpendicular write heads having trailing shields as well. For simplification, structures corresponding to process steps prior to seed layer deposition are not shown for the trailing shield. 
       FIG. 15   a  is a partial cross sectional view  1500  looking into the air bearing surface (ABS) of the film structure subsequent to the deposition of anti-reflective seed layer  1502 , during fabrication of a perpendicular write head with a trailing shield, in accordance with an alternate embodiment of the present invention. In structure  1500 , tapered magnetic pole structure  112 ′, gap layer  112 ′, and filler layer  503  have been previously deposited on substrate  114  and planarized by methods well known to those skilled in the art. 
       FIG. 15   b  is a partial cross sectional view of detail  1504  of  FIG. 15   a , for seed layers  1502  having a optional capping layer  1502   a , in accordance with an alternate embodiment of the present invention. The materials, thickness ranges, reflectivity and other limitations disclosed above for gap layer  110 ′ and seed layer  902 ,  902   a ,  902   b  above apply equally to seed layer  1502 ,  1502   a ,  1502   b  for this alternative embodiment of the present invention. 
       FIG. 16  is a partial cross sectional view  1600  looking into the air bearing surface (ABS) of the film structure subsequent to the deposition of trailing shield  1602 , in accordance with an alternate embodiment of the present invention. The preceding steps of photo resist deposition, exposure, development and removal are not shown, as these processes are self evident to those of skill in the art, and in the light of the forgoing embodiments and discussion. 
     The present invention is not limited by the previous embodiments heretofore described. Rather, the scope of the present invention is to be defined by these descriptions taken together with the attached claims and their equivalents.