Abstract:
A write element for magnetic recording includes a main pole and a shield. The main pole has first and second sides with respect to a down-track direction. The shield at least partially surrounds the main pole with a continuously concave inner sidewall. The angle between the inner sidewall of the shield and the direction of motion of the write element is greater than the angle between the sides of the main pole and the direction of motion.

Description:
SUMMARY 
       [0001]    A shield with inner walls surrounds a main pole. The inner walls of the shield have wall angles with respect to a down track direction that exceed the wall angles of the main pole with respect to a down track direction. One embodiment of the shield resembles a wine glass shaped cavity. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0002]      FIG. 1  is a cross sectional view of a perpendicular magnetic recording head according to an embodiment. 
           [0003]      FIG. 2  is an air bearing surface view of a writer pole and “wine glass” shaped trailing shield according to an embodiment. 
           [0004]      FIG. 3  is a plot of effective magnetic write field as a function of magnetic write width for a writer pole trailing shield with trapezoidal-shaped cavity and for the writer pole wine glass trailing shield cavity of  FIG. 2 . 
           [0005]      FIG. 4  is an air bearing surface view of a writer pole and wine glass trailing shield cavity according to an embodiment. 
           [0006]      FIG. 5  is an air bearing surface view of a writer pole with wine glass trailing shield cavity according to an embodiment. 
           [0007]      FIG. 6  is an air bearing surface view of a writer pole with trailing shield cavity with greater wall angles according to an embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0008]      FIG. 1  is a cross sectional view of an example perpendicular writer  10  in accordance with various embodiments, which includes main pole  12 , return pole  14 , and write coils  16 . Conductive write coils  16  surround back gap closure  17  that magnetically couples main pole  12  to return pole  14 . Perpendicular writer  10  confronts magnetic medium  18  at an air bearing surface (ABS) of main pole  12  and return pole  14 . Main pole  12  includes main pole body  20 , yoke  21 , and main pole tip  22 . Yoke  21  is coupled to an upper surface of main pole body  20 . Main pole tip  22  has a leading edge  24  and a trailing edge  26 . Main pole tip  22  is separated from return pole  14  at the ABS by insulating material  28 . Write gap  35  is defined by the distance between leading edge  24  and return pole  14 . 
         [0009]    Magnetic medium  18  may include magnetically soft underlayer  32  and magnetically hard recording layer  34 . It should be noted that the configuration for perpendicular writer  10  is merely illustrative and many other configurations may alternately be employed in accordance with the present invention. For example, perpendicular writer  10  may include trailing shields, side shields, or wrap around shields that absorb stray magnetic fields from main pole tip  22 , magnetic side tracks on recording layer  34 , and other sources, such as the trailing edge of return pole  14 , during recording. Trailing shield  36  is shown proximate insulating layer  28  that surrounds main pole tip  22  of perpendicular writer  10 . 
         [0010]    Magnetic medium  18  travels or rotates in a direction relative to perpendicular writer  10  as indicated by arrow A. To write data to magnetic medium  18 , an electric current is caused to flow through conductive write coils  16 , which passes through write gap  35 , between main pole  12  and return pole  14 . This induces a magnetic field across write gap  35 . By reversing the direction of the current through conductive coils  16 , the polarity of the data written to magnetic medium  18  is reversed. Main pole  12  operates as the trailing pole and is used to physically write the data to magnetic medium  18 . Accordingly, it is main pole  12  that defines the track width of the written data. More specifically, the track width is defined by the width of trailing edge  26  of main pole tip  22  at the ABS. Main pole  12  may be constructed of a material having a high saturation moment such as NiFe or CoFe or alloys thereof. More specifically, in various embodiments the main pole  12  is constructed as a lamination of layers of magnetic material separated by thin layers of nonmagnetic insulating material  28  such as, for example, aluminum oxide. 
         [0011]    One embodiment is shown in  FIG. 2 , which is a schematic representation of an ABS view of perpendicular writer  110 . As shown in  FIG. 2 , writer  110  includes return pole  114 , main pole  122 , insulator  128 , and trailing shield  136 . Main pole  122  has a trapezoidal pole tip with leading edge  124 , trailing edge  126  and sides  140  and  142 . In this embodiment, shield  136  includes inner sidewalls  150  and  152 , leading edge  154 , trailing edge  156 , throat sidewalls  162  and  164 , and mouth sidewalls  166  and  168 . Leading edge  154  preferably is located closer to return pole  114  than is leading edge  124  of main pole  122 , wherein any stray field may be effectively prevented from reaching the magnetic medium. Inner sidewalls  150  and  152  of shield  136  may not be parallel to sides  140  and  142  of main pole  122 . As one possible result, wall angles θ 2  of shield  136  may be larger than wall angles θ 1  of main pole  122 . The trapezoidal shape is narrower at leading edge  124  than at trailing edge  126  to aid in preventing skew related adjacent track interference during writing while the write head is located at inner and outer portions of a magnetic disc. 
         [0012]    In writer  110 , throat sidewalls  162  and  164  and mouth sidewalls  166  and  168  are adjacent leading edge  154 , thereby possibly minimizing magnetic field concentration in that vicinity during writing. The significance of increasing the wall angle and introducing throat sidewalls  162  and  164  is that, as the size of main pole  122  decreases in response to a demand for higher areal density recording, the effective writing field of magnetic writer  110  may significantly exceed the effective writing field of a writer with a main pole having identical dimensions with shield walls parallel to main pole walls  142 . The shape of the cavity in shield  136  surrounding main pole  122  in writer  110  resembles a wine glass. The length of main pole  122 , L 1 , may be less than the length of shield cavity L 2  and spacing S 1  toward the front of the cavity may be less than spacing S 2  at the back of the cavity. 
         [0013]    To assess how shield shape impacts writing performance, a series of calculations were made of the performance of a writer having a trapezoidal shaped cavity with walls parallel to walls  140  and  142  and writer  110  with a wine glass shaped cavity for a shield. Measured variables were main pole write width, write pole wall angles θ 1 , side shield spacing, and side shield wall angles θ 2 . In the trapezoidal shaped cavities, θ 1 =θ 2 . The dimensions of main poles were the same in both writer configurations. 
         [0014]    Exemplary results of such calculations are shown in  FIG. 3 . In  FIG. 3 , the maximum effective write field H eff (max) is plotted versus the magnetic writer width. The data represent a series of H eff (max) for both writer configurations with identical write current, main pole wall angle, and main pole writer width. The average results for a trapezoidal shaped cavity magnetic writer design with θ 1 =θ 2  are given by curve A. The average results for wine glass writer design  110  are given by curve B. For each case studied in the simulation, the wine glass design gave both consistently higher effective writing fields at a given magnetic write width and narrower magnetic write widths at the same write field. 
         [0015]      FIG. 4  shows a schematic representation of an ABS view of an example perpendicular writer  110 A, which also features a shield with a wine glass shaped cavity. In  FIG. 4 , elements of writer  110 A that are similar to elements of writer  110  are designated with the same reference number followed by the letter “A”. Thus, main pole  122 A of writer  110 A is similar to main pole  122  of writer  110 . In this embodiment, inner sidewalls  150 A and  152 A, throat sidewalls  162 A and  164 A, and mouth sidewalls  166 A and  168 A of shield  136 A are concave, further minimizing magnetic field concentrations in the vicinity of the throat area defined by sidewalls  162 A and  164 A. Wall angles θ 2  of sidewalls  150 A and  152 A may be larger than wall angles θ 1  of main pole  122 A. Length L 1 A of pole  122 A may be less than length L 2 A of the shield cavity and spacing S 1 A toward the front of the cavity may be less than spacing S 2  at the back of the cavity. This design may result in greater effective magnetic fields during writing due to the narrower magnetic footprint of pole  122 A at the ABS. 
         [0016]      FIG. 5  is a schematic representation of an ABS view of perpendicular writer  110 B illustrating another embodiment of the invention featuring a shield with a wineglass shaped cavity. Perpendicular writer  110 B is similar to writers  110  and  110 A, and similar elements are designated with the same reference number followed by the letter “B”. In this embodiment, shield  136 B completely surrounds writer pole  122 B. In  FIG. 5 , the cavity does not extend to leading edge  154 B of shield  136 B. Leading end wall  170 B of the cavity is positioned near, but spaced from shield leading edge  154 B. Curved sidewalls  150 B and  152 B, throat sidewalls  162 B and  164 B, mouth sidewalls  166 B and  168 B and cavity leading end wall  170 B resemble a wine glass. Length L 1 B of pole  122 C may be less than length L 2 B of the shield cavity and spacing S 1 B toward the front of the cavity may be less than spacing S 2 B at the back of the cavity. 
         [0017]      FIG. 6  is a schematic representation of an ABS view of perpendicular writer  110 C illustrating another embodiment of the invention. Writer  110 C is similar to writers  110 ,  110 A, and  110 B, and similar elements are designated with the same reference number followed by the letter “C”. In this embodiment, trailing shield  110 C completely surrounds main pole  122 C and the cavity does not extend to leading edge  154 C of shield  110 C. Sidewalls  150 C and  152 C form wall angles θ 2  that are larger than wall angles θ 1  of main pole  122 C. The cavity resembles a wine glass without a stem. That is, the cavity resembles the bowl of a wine glass. Length L 1 C of pole  122 C may be less than length L 2 C of the shield cavity and spacing S 1 C toward the front of the cavity may be less than length S 2 C at the back of the cavity. 
         [0018]    Differences in the shape and dimensions of the trailing shield with respect to the main pole dimensions are key parameters in defining the magnetic bit shape on the recording medium. The wine glass writer design may allow the magnetic write width to be varied by the shield geometry as well as by the main pole geometry. As shown in  FIG. 3 , the magnetic writer width of any effective write field can be decreased by the inventive shield geometries disclosed herein. As a result, referring to  FIG. 2 , for instance, leading edge  124 , trailing edge  126  and wall angles θ 1  can be made smaller while pole  122  produces the same write field. Another benefit is that trapezoidal main poles with smaller wall angles are easier to fabricate, thereby decreasing the manufacturing costs. 
         [0019]    Write pole fabrication by damascene processing is a fabrication method. Pole fabrication by damascene processing is described in commonly owned U.S. Pat. No. 6,949,833 and patent application Ser. No. 12/491,898 and incorporated herein in their entirety by reference.  FIG. 7  illustrates exemplary steps to form a pole in an insulator layer such as layer  128  in  FIG. 2 . First, an insulator layer is formed on a substrate (Step  200 ). The insulator layer is preferably aluminum oxide although other insulator materials known in the art such as SiOx, MgO, SiC, etc. may be used. 
         [0020]    Next, a trench is formed in the insulator layer (Step  210 ). The cross section of the trench is preferably trapezoidal as shown by pole  122  in  FIG. 2 . A seedlayer is then deposited on the walls and bottom of the trench to assist in formation of pole  122  (Step  220 ). A seedlayer is necessary to control the quality of subsequent layers deposited in the trench and can be deposited by plating, sputtering, or other material deposition techniques. An electrically conducting seedlayer is necessary if subsequent layers are to be deposited by electroplating. 
         [0021]    A layer of magnetic material is then deposited on the seedlayer (Step  230 ). As discussed earlier, NiFe, CoFe, or alloys thereof are preferred. The magnetic layer can be deposited by electroplating, sputtering, or other methods of material deposition. Laminated pole structures provide improved write performance. The next step is to deposit a layer of nonmagnetic material on the magnetic material (Step  240 ). Nonmagnetic materials suitable for use as a spacer layer are tantalum, ruthenium, aluminum oxide, magnesium oxide, and others. In the next step, the process is repeated until the trench is filled and the pole is formed (Step  250 ). The process then proceeds to the next manufacturing cycle (Step  260 ). 
         [0022]    Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.