Abstract:
For high track density recording, tighter reader and writer track width control are essential. This has been achieved by using a plated NiPd write gap which is self-aligned with a plated 23 KG pole material. Heat dissipation by the writer is thus improved since alumina has been replaced with nonmagnetic metal materials, such as Ru, leading to less pole tip protrusion which in turn leads to better writer track width control

Description:
FIELD OF THE INVENTION 
   The invention relates to the general field of magnetic write heads with particular reference to an improved top pole piece. 
   BACKGROUND OF THE INVENTION 
   For high track density recording, tighter reader and writer track width control is the key ingredient for obtaining high yield. How to continue improving the writer track width by using a pole trim process together with a narrow pole width is a challenging task. The basic principle to having tighter pole width control is to have a thinner pole resist process so that photo CD (critical dimension) control can be further improved. Reducing the amount of pole material consumed during the pole trim process, without impacting performance, is the key factor associated with using a thinner pole resist. 
   There have been several proposals to utilize a plated S 2  (writer lower shield), a plated write gap, and a plated P 2  (top pole) in a single photo process thereby minimizing the extent of pole trim consumption. However, with this scheme the throat height definition is rather poor so this type of design creates magnetic flux leakage between pole and shield. So poor overwrite is a consequence of this type of design. 
   The present invention discloses an improved scheme that applies to both stitched writers and planar writers. 
   A routine search of the prior art was performed with the following references of interest being found: 
   In U.S. Pat. No. 6,594,112, Crue et al. disclose NiPd plating to more accurately define throat height. Alumina is used as the insulating material. In U.S. Pat. No. 6,621,659, Shukh et al. show alumina in the recess to define throat height. 
   SUMMARY OF THE INVENTION 
   It has been an object of at least one embodiment of the present invention to reduce the amount of pole material consumed during pole trimming. 
   Another object of at least one embodiment of the present invention has been to facilitate use of thinner photoresist during formation of the top pole. 
   Still another object of at least one embodiment of the present invention has been to improve heat dissipation by the write head. 
   A further object of at least one embodiment of the present invention has been to provide a process to manufacture said write head. 
   These objects have been achieved by using a plated NiPd write gap and self-aligning with a plated 24 KG pole material. Heat dissipation by the writer is thus improved since alumina has been replaced with nonmagnetic metal materials, such as Ru, leading to less pole tip protrusion which in turn leads to better writer track width control. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows the starting point for the construction of the present invention. 
       FIGS. 2 and 3  show how lower pole and back pieces are to be separated. 
       FIGS. 4 and 5  show the formation, in automatic alignment, of the write gap and the lower pole piece. 
       FIG. 6  shows formation of the end piece. 
       FIGS. 7 and 8  are ABS views of  FIG. 6 . 
       FIG. 9  shows the starting point for manufacturing a planar writer according to the teachings of the present invention. 
       FIGS. 10–13  illustrate the formation of the write coils and the lower pole structure. 
       FIGS. 14 and 15  show the formation of the top pole and end piece. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In this invention we disclose a plated NiPd write gap and a plated 24 KG P 2  in conjunction with a modified TH (throat height) definition method to overcome the poor TH definition problems associated with the prior art. The invention leads to a reduced amount of pole consumption by using a self-aligned plating process for the formation of the write gap and the top pole. 
   We begin a non-specific description of the present invention by referring to  FIG. 1 . Seen there is read head  14  which is sandwiched between its shields  13  and  15 . Insulating layer  12  serves to isolate the top read shield  13  from lower write shield  11 . 
   The method of the present invention begins, as shown in  FIG. 2 , with the deposition onto lower shield  11  of seed layer  21  which is characterized by having a magnetic moment of at least 24 kilogauss. Seed layer  21  could be CoFeN or CoFe and is deposited to a thickness between about 1,000 and 5,000 Angstroms. Then, as shown in  FIG. 3 , trench  31  is formed in seed layer  21 . Trench  31  extends down as far as the top surface of shield  11  and has sloping sidewalls. The width of trench  31  will determine the throat depth of the writer. 
   Trench  31  is then just filled with layer of a non-magnetic metal  32  by means of sputtering. We have typically preferred ruthenium for metal  32  but other non-magnetic metals such as NiCu, Cu, Rh, or NiCr could also have been used. 
   Referring now to  FIG. 4 , photoresist mold  41  is formed, as shown, and then write gap layer  51  is electroplated onto the floor of mold  41 . Gap layer  51  is preferably NiPd but similar materials such as NiP or Pt could also have been used. It is deposited to a thickness between about 700 and 1,500 Angstroms. The mold is positioned so that write gap layer  51  overlaps both seed layer  21  and non-magnetic metal layer  32 . Then, with the mold still in place, upper pole piece  52  is formed by electroplating onto write gap layer  51  (inside the mold). Upper pole piece  52  is made of a material such as CoNiFe and it is deposited to a thickness between about 2 and 4 microns. The structure, after removal of all photoresist is shown in  FIG. 5 . 
   The general method concludes with the formation of back gap piece  61  that is in magnetic contact with seed layer  21  and with upper pole piece  52 , said back gap piece not overlapping the write gap layer.  FIGS. 7 and 8  are ABS (air bearing surface) views of  FIG. 6  and of  FIG. 6  after its left edge has been planarized. 
   We will now disclose a process for a more specific embodiment of the present invention namely a the manufacture of a planar write. As noted earlier, the process is of a more general nature can, in general, be applied to write heads of any shape or design. 
   Referring now to  FIG. 9 , the process begins with the provision of lower magnetic shield layer  112  on which is formed dielectric disc  16 . Lower coil  17  is then formed on disc  16 . Then, as shown in  FIG. 10 , layer of ferromagnetic material  18  is deposited and patterned to form the bottom section of the lower pole which includes centrally located lower trench  42  on whose floor rests dielectric disc  16  and lower coil  17 . 
   Then, as seen in  FIG. 11 , lower trench  42  is overfilled with insulating material  44  and then planarized, giving it the appearance seen in  FIG. 12 , following which insulating layer  136  is deposited and patterned to form a lid that fully covers lower coil  17  as seen in  FIG. 13 . Upper coil  137  is then formed on lid  136  and additional ferromagnetic material is deposited and patterned to complete formation of lower pole  18  which is then filled with insulation  138 . 
   The top (coplanar) surfaces of elements  11  and  138  in  FIG. 13  are equivalent to the top surface of element  11  in  FIGS. 1–5 . From this point the formation of the planar reader proceeds along the line previously recited for the general method: 
   Seed layer  21 , having a magnetic moment of at least 24 kilogauss, is deposited on the top surfaces of  11  and  138  and non-magnetic metal filled trench  32  is formed. Using a photoresist mold, as described earlier, top pole  52  is electro-formed on write gap layer  51 , said write gap layer overlapping both seed layer  21  and layer of a non-magnetic metal  32 , as shown in  FIG. 14 . 
   To complete the structure, back gap piece  61 , that is in magnetic contact with the seed layer and with the upper pole piece and that does not overlap the write gap layer is formed, as shown in  FIG. 15 . 
   We conclude by noting that the present invention, as disclosed above, offers the following advantages:
     1. Less P 2  consumption due to self-aligned plated NiPd write gap and plated 24 KG pole material.   2. Thinner P 2  resist can be used and tighter control, both within a single wafer and from wafer to wafer can be expected. A thinner resist allows greater photo-processing latitude (depth of focus, for example) which in turn leads to better P 2  CD (critical dimension) control.   3. A modified TH definition process can further reduce the P 2  consumption.   4. Heat dissipation by the writer is improved by replacing alumina with nonmagnetic metal materials, such as Ru, NiCu, Cu; etc (layer  32 ), leading to less pole tip protrusion   5. Better writer track width control.   6. A simplified writer process.