Abstract:
A magnetic recording head comprises a write pole including a throat region with a leading edge, a trailing edge opposite the leading edge, and first and second side edges opposite one another. The magnetic recording head further comprises a first side wall gap layer disposed alongside the first side edge of the throat region, and a second side wall gap layer disposed alongside the second side edge of the throat region. Each of the first and second side wall gap layers has a first width at the leading edge of the throat region smaller than a second width at the trailing edge of the throat region.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 12/426,264, filed on Apr. 19, 2009, which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to hard disk drives and, in particular, relates to a write head with variable side shield gaps. 
     BACKGROUND OF THE INVENTION 
     In order to increase the recording density of magnetic storage devices, the performance of the write head of a hard disk drive plays an increasingly important role. Current writers with trailing shields suffer from several major shortcomings. For example, the cross-track field gradients of such write heads are poor, which can result in adjacent track interference (ATI). In this regard, writers with trailing shields tend to have large stray fields, which can result in adjacent track erasure. One approach to solving this ATI issue involves providing “wrap-around” shields, in which additional shield layers are disposed on opposite sides of the write head in the cross-track direction. While many side shield configurations have been proposed, most present design and fabrication challenges, while still suffering from an unsatisfactory level of ATI. 
     SUMMARY OF THE INVENTION 
     Various embodiments of the present invention solve the foregoing problem by providing magnetic recording heads having variable side shield gaps, whereby a trailing edge of a side shield is spaced further (in the cross-track direction) from the magnetic pole than a leading edge thereof. This configuration enjoys improved cross-track field gradients, can be accomplished with mill &amp; lap or damascene process flows, is compatible with beveled heads, and may permit the use of more easily-fabricated rectangular cross-sectional write poles. 
     According to one aspect of the subject disclosure, a magnetic recording head is provided. The magnetic recording head comprises a write pole including a throat region with a leading edge, a trailing edge opposite the leading edge, and first and second side edges opposite one another. The magnetic recording head further comprises a first side wall gap layer disposed alongside the first side edge of the throat region, and a second side wall gap layer disposed alongside the second side edge of the throat region. Each of the first and second side wall gap layers has a first width at the leading edge of the throat region smaller than a second width at the trailing edge of the throat region. 
     According to another aspect of the subject disclosure, a method of making a magnetic recording head comprises the steps of forming a write pole extending above a field area, forming shadowing structures on opposite sides of the write pole, and depositing a side wall gap material onto opposing faces of the write pole, whereby side wall gap layers are formed on the opposing faces of the writer pole. The shadowing structures are configured to shadow a lower portion of the write pole such that the deposited side wall gap layers are thinner adjacent the lower portion and thicker adjacent a region above the lower portion. 
     It is to be understood that both the foregoing summary of the invention and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings: 
         FIG. 1  illustrates a cross-sectional view of a magnetic recording head in accordance with one aspect of the subject disclosure; 
         FIGS. 2A and 2B  illustrate cross-sectional views of a magnetic recording head in accordance with one aspect of the subject disclosure; 
         FIGS. 3A-3C  graphically illustrate a method of making a magnetic recording head in accordance with one aspect of the subject disclosure; 
         FIG. 4  is a flow chart illustrating a method of making a magnetic recording head in accordance with one aspect of the subject disclosure; and 
         FIGS. 5A and 5B  are FEM field contours of write heads with and without variable side shield gaps, in accordance with one aspect of the subject disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following detailed description, numerous specific details are set forth to provide a full understanding of the present invention. It will be apparent, however, to one ordinarily skilled in the art that the present invention may be practiced without some of these specific details. In other instances, well-known structures and techniques have not been shown in detail to avoid unnecessarily obscuring the present invention. 
       FIG. 1  illustrates a cross-sectional view (from the perspective of the air bearing surface) of a magnetic recording head  100  in accordance with one aspect of the subject disclosure. Magnetic recording head includes a write pole  101  surrounded by a leading shield  102  and a trailing shield  103 . Magnetic recording head may further include a write gap layer  104  separating a trailing edge of write pole  101  from trailing shield  103 . Write pole  101  is further surrounded (in the cross-track direction) by two side shields  105   a  and  105   b . Separating write pole  101  from side shields  105   a  and  105   b  are side gap layers  106   a  and  106   b , respectively. As can be seen with reference to  FIG. 1 , each side gap layer is wider at the trailing edge of write pole  101  than at the leading edge thereof. In particular, at the trailing edge of write pole  101 , side gap layer  106   a  has a width G TE , and at the leading edge of write pole  101 , side gap layer  106   a  has a width G LE , where G TE &gt;G LE . Side gap layer  106   b  is similarly configured, mirroring side gap layer  106   a.    
     According to one aspect of the subject disclosure, G TE  may be between 4 and 8 times the write gap of the magnetic recording head, while G LE  may be between 2 and 3.5 times the write gap of the magnetic recording head. The scope of the present invention is not limited to these particular dimensions, however, as a write pole may be provided with variable side gap layers of nearly any ratio of sizes. 
     The variable width side gap layers  105   a  and  105   b  extend away from the air bearing surface (e.g., along the nose length of write pole  101 ), as can be seen with reference to  FIGS. 2A  and  2 B, which illustrate magnetic recording head  100  in cross-section along planes A-A and B-B, respectively, in accordance with one aspect of the subject disclosure. As can be seen when comparing  FIG. 2A  to  FIG. 2B , side gap layers  106   a  and  106   b  are wider nearer the trailing edge of write pole  101  (e.g., in  FIG. 2A ) than they are near the leading edge of write pole  101  (e.g., in  FIG. 2B ). 
     According to one aspect of the subject disclosure, the side shields  105   a  and  105   b  extend along a throat region  201  of write pole  201  and partway along a yoke region  202  thereof. Accordingly, as can be seen with reference to  FIGS. 2A and 2B , variable width side gap layers  106   a  and  106   b  also extend along the throat region  201  and partway along the yoke region  202  of write pole  101 , conformal with write pole  101 . 
     According to one aspect of the subject disclosure, side gap layers  106   a  and  106   b  are symmetric (e.g., mirror images of one another). The scope of the present invention is not limited to such an arrangement, however, as a magnetic recording head may comprise a write pole surrounded by side gap layers of differently varying widths. Moreover, while the foregoing exemplary magnetic recording head is illustrated as having side gap layers with linearly increasing width from the leading edge to the trailing edge, the scope of the present invention is not limited to such an arrangement. Rather, magnetic recording heads may comprise a write pole surrounded by side gap layers that increase in width from the leading edge to the trailing edge non-linearly, discontinuously (e.g., in steps, or with regions of lesser width between regions of greater width), or in any number of other manners readily understood by those of skill in the art. 
     A magnetic recording head configured with a write pole surrounded by side gap layers of varying width, such as magnetic recording head  100 , enjoys a number of performance advantages and ease of manufacture when compared with other magnetic recording head designs. For example, the larger side gap layer at the trailing edge of the write pole ensures that more magnetic flux passes through the leading edge regions of the side shields during an operation of the magnetic recording head than through the trailing edge regions thereof. Such an effect makes it possible to use a write pole with a rectangular cross-section (as viewed from the ABS) with a head field bubble similar to that of a trapezoidal cross-sectional pole which lacks the variable side shield gap layers. As will be readily understood by those of requisite skill in the art, a write pole with a rectangular cross section is far simpler to manufacture using simpler wafer fabrication techniques. 
     Turning to  FIGS. 3A-3C , a method of making a magnetic recording head is graphically illustrated in accordance with one aspect of the subject disclosure. In  FIG. 3A , a write pole  301  is illustrated in cross section (from an ABS view). Write pole  301  is formed over substrate  302  (e.g., by a damascene process, or by an additive “mill and lap” process). On either side of write pole  301  are illustrated regions of magnetic pole material from which write pole  301  has been formed, which regions  303   a  and  303   b  have not been stripped away from the wafer. It should be noted that  FIG. 3A  is not illustrated to scale, as the field area between write pole  301  and regions  303   a  and  303   b  may be many orders of magnitude larger than is illustrated in  FIG. 3A . To facilitate the formation of variable side gap layers on write pole  301 , shadowing structures  304   a  and  304   b  are formed on opposite sides thereof, as illustrated in  FIG. 3B . These shadowing structures will allow a side gap material to be preferentially deposited on upper regions of write pole  301 , as illustrated in  FIG. 3C . The shadowing structures  304   a  and  304   b  may be formed by spin coating a photoresist material, or may be any other suitable material known to those of skill in the art, and may be formed on opposite sides of write pole  301  by any one of a number of methods well known to those of skill in the art. Moreover, it is not necessary that shadowing structures  304   a  and  304   b  be formed over pre-existing regions of the magnetic pole material layer, and may be formed directly upon substrate  302 . 
       FIG. 3C  illustrates the deposition of a side gap material  305  on either side of trapezoidal write pole  301  (and over the top of write pole  301 , where side gap material  305  may be left to function as a write gap material, or from where side gap material  305  may be removed in a subsequent processing step). As can be seen with reference to  FIG. 3C , the shadowing structures have partially shadowed lower regions of write pole  301 , such that side gap material  305  has been preferentially deposited on upper regions of write pole  301 , whereby the width of side gap material  305  at a trailing edge (the upper edge in  FIG. 3C ) of write pole  301  is greater than a width of side gap material  305  at a leading edge (the lower edge in  FIG. 3C ) of write pole  301 . According to one aspect of the subject disclosure, following the deposition of the variable side gap layers on write pole  301 , subsequent processing steps may provide write pole  301  with a beveled upper surface, without negatively impacting the variable side gap layers. 
     While in the foregoing exemplary embodiments, the write pole has been illustrated as trapezoidal, the scope of the present invention is not limited to such an arrangement. Rather, as will be readily understood by those of skill in the art, the present invention has application to write poles with any one of a number of cross-sectional shapes, including trapezoidal, triangular, rectangular, and any other cross-sectional shape known by those of skill in the art to be suitable for a write pole. 
       FIG. 4  is a flow chart illustrating a method of making a magnetic recording head in accordance with one aspect of the subject disclosure. The method begins in step  401 , in which a write pole is formed extending above a field area. In step  402 , shadowing structures are formed on opposite sides of the write pole. A side wall gap material is deposited onto opposing faces of the write pole in step  403 , whereby side wall gap layers are formed on the opposing faces of the writer pole. The shadowing structures are configured to shadow a lower portion of the write pole such that the deposited side wall gap layers are thinner adjacent the lower portion and thicker adjacent a region above the lower portion. 
       FIGS. 5A and 5B  are FEM field contours of write heads with and without variable side shield gaps, respectively, in accordance with one aspect of the subject disclosure. As can be seen when comparing  FIG. 5A  (the FEM field contour of a write head with variable side shield gaps) to  FIG. 5B , the FEM field contour of  FIG. 5A  has a much improved field gradient in the cross-track direction, which provides for greatly improved ATI performance. 
     The description of the invention is provided to enable any person skilled in the art to practice the various embodiments described herein. While the present invention has been particularly described with reference to the various figures and embodiments, it should be understood that these are for illustration purposes only and should not be taken as limiting the scope of the invention. 
     There may be many other ways to implement the invention. Various functions and elements described herein may be partitioned differently from those shown without departing from the spirit and scope of the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and generic principles defined herein may be applied to other embodiments. Thus, many changes and modifications may be made to the invention, by one having ordinary skill in the art, without departing from the spirit and scope of the invention. 
     A reference to an element in the singular is not intended to mean “one and only one” unless specifically stated, but rather “one or more.” The term “some” refers to one or more. Underlined and/or italicized headings and subheadings are used for convenience only, do not limit the invention, and are not referred to in connection with the interpretation of the description of the invention. All structural and functional equivalents to the elements of the various embodiments of the invention described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and intended to be encompassed by the invention. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the above description.