Patent Document

BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates generally to magnetic heads having inductive write head structures, and more particularly to such magnetic heads having heat sink structures formed therein for the dissipation of heat generated by the inductive write head.  
         [0003]     2. Description of the Prior Art  
         [0004]     Hard disk drives include magnetic heads that are designed to write data onto narrow data tracks upon the data disk of the disk drive, and to read data from the narrow data tracks. The ongoing effort to increase the areal data storage density of the hard disk drive results in the development and usage of ever smaller and increasingly delicate magnetic pole tips and magnetoresistive sensors for writing and reading increasingly smaller data bits onto the disk.  
         [0005]     As is well known, the data writing process involves the use of an induction coil to generate magnetic fields within the magnetic poles of the write head, and the electrical current within the induction coil generates a significant amount of heat. The delicate pole tips and magnetoresistive sensor structures are increasingly susceptible to heat caused malfunction and damage as the size of these structures is diminished. It is therefore desirable to incorporate heat sink structures within the magnetic head that function to draw the unwanted heat away from the delicate magnetic head structures in order to promote operational reliability of the magnetic head, and to facilitate the development of smaller pole tips and sensor structures. The magnetic head of the present invention includes such heat sink structures, as is described hereinbelow.  
       SUMMARY OF THE INVENTION  
       [0006]     In the magnetic head of the present invention a heat sink structure is disposed proximate the induction coil within the write head portion of the magnetic head to draw heat away from the sensitive pole tip and magnetoresistive sensor components of the head. In a first embodiment, a heat sink is fabricated above the second magnetic pole, and preferably in the same fabrication steps in which an electrical lead for the induction coil is fabricated. The heat sink is therefore fabricated subsequent to the fabrication of the more delicate components of the magnetic head, and therefore does not interfere with the intricate fabrication process steps for creating these components. In the preferred embodiment, the heat sink is fabricated photolithographically in the same process step in which the electrical lead to the center tap of the induction coil is fabricated, and the only difference in the magnetic head fabrication process is the modification of the photolithographic mask that is used to create the electroplating trench in which the electrical lead is electroplated. The change to the mask involves the creation of a second opening within the mask for the creation of an electroplating trench at the location of the heat sink. Thereafter, the heat sink is electroplated into its trench during the same electroplating step in which the electrical lead is electroplated into its trench.  
         [0007]     Further embodiments of the invention include the fabrication of a second heat sink beneath the first magnetic pole, and the fabrication of thermal interconnects between the two heat sinks, and the fabrication of a thermal interconnect to the slider body for enhanced thermal dissipation.  
         [0008]     It is an advantage of the magnetic head of the present invention that a heat sink is provided to protect sensitive components of the magnetic head from excessive operational heat.  
         [0009]     It is another advantage of the magnetic head of the present invention that the fabrication of the heat sink is accomplished subsequent to the fabrication of delicate components of the magnetic head.  
         [0010]     It is a further advantage of the magnetic head of the present invention that the pre-existing process for fabricating the delicate components of the magnetic head is not altered by the fabrication of the heat sink.  
         [0011]     It is an advantage of the hard disk drive of the present invention that it includes a magnetic head of the present invention in which a heat sink is provided to protect sensitive components of the magnetic head from excessive operational heat.  
         [0012]     It is an advantage of the process for fabricating a magnetic head of the present invention that the heat sink is fabricated in the same fabrication steps for the creation of the electrical leads to the induction coil of the magnetic head.  
         [0013]     It is another advantage of the process for fabricating a magnetic head of the present invention that the only significant alteration in the process for fabricating the magnetic head is the alteration of the photolithographic mask which is utilized to fabricate an electrical lead of the induction coil of the magnetic head.  
         [0014]     These and other features and advantages of the present invention will no doubt become apparent to those skilled in the art upon reading the following detailed description which makes reference to the several figures of the drawing. 
     
    
     IN THE DRAWINGS  
       [0015]     The following drawings are not made to scale as an actual device, and are provided for illustration of the invention described herein.  
         [0016]      FIG. 1  is a schematic top plan view of a hard disk drive including the magnetic head of the present invention;  
         [0017]      FIG. 2  is a top plan view depicting various components of a prior art magnetic head;  
         [0018]      FIG. 3  is a side cross-sectional view taken along lines  3 - 3  of  FIG. 2 ;  
         [0019]      FIG. 4  is a top plan view depicting various components of a magnetic head of the present invention;  
         [0020]      FIG. 5  is a side cross-sectional view taken along lines  5 - 5  of  FIG. 4 ;  
         [0021]      FIG. 6  is a top plan view depicting various components of another embodiment of the magnetic head of the present invention;  
         [0022]      FIG. 7  is a side cross-sectional view of the device depicted in  FIG. 6 , taken along lines  7 - 7  of  FIG. 6 ; and  
         [0023]      FIG. 8  is a side cross-sectional view showing improvements in the device depicted in  FIG. 7  accomplished by the removal of certain insulation layers. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]     A simplified top plan view of a typical hard disk drive  10  which includes a magnetic head of the present invention is presented in  FIG. 1 . As depicted therein, at least one hard disk  14  is rotatably mounted upon a motorized spindle  18 . A slider  22 , having a magnetic head  26  disposed thereon, is mounted upon an actuator arm  30  to fly above the surface of each rotating hard disk  14 , as is well known to those skilled in the art. The present invention includes improved features and manufacturing methods for such magnetic heads, and to better describe the present invention a prior art magnetic head is next described.  
         [0025]     As will be understood by those skilled in the art,  FIG. 2  is a top plan view and  FIG. 3  is a side cross-sectional view taken along lines  3 - 3  of  FIG. 2  that depict portions of a prior art magnetic head  38 , termed a longitudinal magnetic head. As is best seen in  FIG. 3 , the magnetic head  38  includes a first magnetic shield layer (S 1 )  40  that is formed upon a surface  44  of the slider body material  22 . A read head sensor element  52  is disposed within electrical insulation layers  54  and  56  and a second magnetic shield layer (S 2 )  58  is formed upon the insulation layer  56 . An electrical insulation layer  59  is then deposited upon the S 2  shield  58 , and a first magnetic pole (P 1 )  60  is fabricated upon the insulation layer  59 .  
         [0026]     Following the fabrication of the P 1  pole  60 , a write gap layer  72  is deposited upon the P 1  pole  60 , followed by the fabrication of a P 2  magnetic pole tip  76 . An induction coil structure including coil turns  80  is then fabricated within insulation  82  above the write gap layer  72 . Thereafter, a yoke portion  84  of the second magnetic pole is fabricated in magnetic connection with the P 2  pole tip  76 , and through back gap element  90  to the P 1  pole  60 . An insulation layer  94  is deposited above the yoke  84  and an electrical interconnect  98 , typically composed of copper, is electroplated within a via that is formed through the insulation layer  94  down to the electrical center tap  102  of the coil  80 . An electrical lead  106  is next fabricated upon the insulation layer  94  from the interconnect  98  to an electrical contact pad  108  of the magnetic head  38 . The electrical lead  106  may be fabricated in a photolithographic process in which a seed layer  110 , typically composed of copper, is deposited upon the insulation layer  94 , followed by the fabrication of a patterned photoresist layer (not shown) in which an electrical lead trench (not shown) is formed. Thereafter, the electrical lead  106  is electroplated onto the seed layer within the trench. The photoresist and seed layer are subsequently removed (except the seed layer  110  beneath the electrical lead  106 ), and a further insulation layer  114  is deposited to encapsulate the magnetic head including the electrical lead  106 . It is to be noted that the encapsulating insulation layer  114  is not depicted in  FIG. 2 , such that the electrical lead  106  and other components can be better seen. The other electrical lead  115  that connects the outer coil turn of the coil  80  with the contact pad  117  may be fabricated at the same time as the lead  106 . The magnetic head  38  is subsequently fabricated such that an air bearing surface (ABS)  116  is created.  
         [0027]     It is to be understood that there are many detailed features and fabrication steps of the magnetic head  38  that are well known to those skilled in the art, and which are not deemed necessary to describe herein in order to provide a full understanding of the present invention.  
         [0028]     As will be understood from the following detailed description, the magnetic head of the present invention includes heat sink structures that are fabricated within the magnetic head to draw away excess heat that is generated within the induction coil and magnetic poles during the inductive write head operation.  FIG. 4  is a top plan view depicting various components of a first embodiment of a magnetic head  118  of the present invention, and  FIG. 5  is a side cross-sectional view of the magnetic head depicted in  FIG. 4 , taken along lines  5 - 5  of  FIG. 4 . The magnetic head of the present invention, as depicted in  FIGS. 4 and 5  includes many structures and components of the prior art magnetic head depicted in  FIGS. 2 and 3 , and similar structures are similarly numbered for ease of comprehension. Therefore, as depicted in  FIGS. 4 and 5 , the magnetic head of the present invention may include a first magnetic shield layer (S 1 )  40  that is formed on a slider body  22 , a read head sensor element  52  that is disposed within insulating layers  54  and  56 , and a second magnetic shield layer (S 2 )  58  that is formed upon the insulation layer  56 . An electrical insulation layer  59  is deposited upon the S 2  shield  58 , and a first magnetic pole (P 1 )  60  is fabricated upon the insulation layer  59 . A write gap layer  72  is deposited upon the P 1  pole  60 , a P 2  magnetic pole tip  76  is fabricated upon the write gap layer and an induction coil having coil turns  80  is fabricated within insulation  82  upon the write gap layer  72 . Thereafter, a yoke portion  84  of the second magnetic pole is fabricated in magnetic connection with the P 2  pole tip  76 , and through the back gap element  90  to the P 1  pole  60 . Thereafter, an insulation layer  94  and an electrical interconnect  98  to the center tap  102  of the induction coil  80  is fabricated.  
         [0029]     A heat sink structure  120  is next fabricated in the same electroplating steps in which the electrical lead  106  is fabricated. Particularly, following the deposition of the seed layer  110  upon the insulation layer  94  and a photoresist (not shown), the mask (not shown) that is utilized to fabricate the electrical lead trench for electroplating the electrical lead  106  is modified to simultaneously create a heat sink trench in a location above the yoke  84 . Thereafter, when the electrical lead  106  is plated up into its trench, as is accomplished in the prior art magnetic head  38 , the heat sink  120  is simultaneously plated up within the heat sink trench. The heat sink  120  is therefore plated up in the same layer of the magnetic head in which the electrical lead  106  is fabricated, and thus the heat sink  120  may be said to be coplanar with the electrical lead  106 .  
         [0030]     Following the removal of the photoresist and exposed seed layer, the encapsulation insulation layer  114  is deposited. The heat sink  120  may be formed in many shapes, and the heat sink  120  depicted in  FIGS. 4 and 5  has a substantial portion  128  disposed above the yoke which is interconnected with a further substantial portion  132  that is fabricated away from the yoke  84  and toward the upper regions of the magnetic head structure. Heat generated in the yoke area is absorbed by the portion  128  of the heat sink  120  that is disposed above the yoke and conducted off to the further substantial portion  132  of the heat sink that is disposed in the upper regions of the head  118 .  
         [0031]     Significantly, this method of fabricating the heat sink  120  adds no new fabrication step to the magnetic head fabrication process. Rather, the fabrication of the heat sink  120  is accomplished by the simple step of modifying the electrical lead mask. It is therefore to be further understood that the magnetic head  118  of the present invention makes no significant changes in the fabrication of the read head portion of the magnetic head, and significantly that there is only a minimal change (in the electrical lead mask) to the fabrication of the write head portion of the magnetic head. Furthermore, the change to the fabrication of the magnetic head structures occurs after the critical features, (such as the read sensor  52  and P 2  pole tip  76 ) have been fabricated.  
         [0032]     Significant features of the heat sink  120  as depicted in  FIGS. 4 and 5  are that the front edge  136  of the heat sink is fabricated back away from the ABS  116  of the head  118 . This is important because where the heat sink is comprised of copper, corrosion and tribological problems are created when copper components are exposed at the ABS of a magnetic head. It is also to be noted that the embodiment of a heat sink  120  depicted in  FIGS. 4 and 5  is not connected to other structures within the magnetic head. It functions to draw heat from the induction coil area for thermal dissipation within the non-critical upper regions of the magnetic head. Critical structures such as the read head sensor  52  and P 2  pole tip  74  are thereby protected from excessive heat buildup during the operation of the inductive write head. In alternative embodiments, the heat sink  120  can be thermally interconnected by at least one interconnection member formed within the magnetic head to other heat sink structures, and/or to the slider body  22  for enhanced heat dissipation therewithin. An alternative embodiment of the present invention having such enhanced heat sink structures is next described with the aid of  FIGS. 6 and 7 .  
         [0033]      FIG. 6  is a top plan view of a magnetic head  140  of the present invention that is created in a head design style that is termed a perpendicular head, and  FIG. 7  is a side cross-sectional view of the head depicted in  FIG. 6 , where  FIG. 7  is taken along lines  7 - 7  of  FIG. 6 . As can best be seen in  FIG. 7 , the perpendicular magnetic head includes a read head portion that is similar to the read head depicted in  FIGS. 2 and 4 . That is, it includes a first magnetic shield layer (S 1 )  40  that is formed upon a slider body  22 , a read head sensor element  52  that is disposed within insulating layers  54  and  56 , and a second magnetic shield layer (S 2 )  58  that is formed upon the insulation layer  56 . An electrical insulation layer  59  is deposited upon the S 2  shield  58 .  
         [0034]     A lower heat sink structure  144  is next fabricated upon the electrical insulation layer  59 . The lower heat sink structure may be fabricated utilizing well known photolithographic techniques in which a seed layer  148  typically comprised of copper, is deposited, followed by the fabrication of a photoresist layer (not shown) having a heat sink trench formed therein, followed by the electroplating of the lower heat sink structure  144  that is preferably comprised of copper upon the seed layer  148  within the trench. Thereafter, the photoresist and excess seed layer are removed, and insulation material such as alumina  150  is deposited, and a chemical mechanical polishing (CMP) step is performed to create a flat upper surface to the heat sink structure  144  for the continued fabrication of further magnetic head structures. This photolithographic process for forming the lower heat sink  144  is substantially similar to the process for fabricating the electrical lead and heat sink of the magnetic head embodiment  118  depicted in  FIGS. 4 and 5 . A significant feature of the lower heat sink structure  144  is that it is fabricated away from the air bearing surface  116  of the magnetic head to avoid corrosion and tribological problems that can be created where copper components are exposed at the ABS; thus a portion of the insulation  150  that surrounds the lower heat sink  144  is exposed at the ABS.  
         [0035]     A further insulation layer  152  is next deposited upon the heat sink  144  and a first magnetic pole structure  156 , termed a shaping pole, is fabricated upon the insulation layer  152 . Thereafter, a narrow pole tip  160  of the perpendicular magnetic head is fabricated upon the first magnetic pole structure  156 . In this perpendicular magnetic head  140 , it is significant that the shaping pole  156  is spaced away from the ABS  116  by insulation  164  in which the pole is fabricated, such that only the pole tip  160  is exposed at the ABS. Thereafter, a further insulation layer  170  is fabricated upon the pole tip  160  and shaping pole  156 , and an induction coil structure, typically comprised of copper coil turns  178 , that is formed within electrical insulation  182 , is fabricated upon the insulation layer  170 . Thereafter, a second magnetic pole  186  is fabricated above the induction coil insulation  182 . The second magnetic pole  186  includes a relatively broad magnetic flux return pole tip  190  together with a yoke portion  192  that is disposed above the induction coil  178 , and which is magnetically connected through a backgap piece  196  to the shaping pole  156 . The center tap  200  of the induction coil  178  is fabricated behind the interconnection of the yoke with the backgap piece. Thereafter, an electrical insulation layer  208  is deposited and a via for an electrical interconnect is created within the insulation layer  208  down to the center tap  200 , and an electrical interconnect  212  is then electroplated up within the via. Thereafter, as is described hereabove with regard to the magnetic head embodiment  118  depicted in  FIGS. 4 and 5 , an upper heat sink structure  220  is fabricated during the fabrication steps that are conducted to form the electrical lead  228  from the center tap electrical interconnect  212  to the contact pads  230  of the magnetic head. Thus, the upper heat sink  220  may be fabricated in substantially the identical manner as the heat sink  120  of magnetic head  118 . That is, in a photolithographic process in which a seed layer  230  is first deposited and the heat sink  220  and electrical leads  228  are electroplated within photoresist trenches. The photoresist and uncovered seed layer are thereafter removed, and an encapsulation layer  231  is subsequently deposited upon the magnetic head structures.  
         [0036]     As is best seen in the top view of  FIG. 6 , the upper heat sink  220  is preferably formed with a first enlarged portion  232  that is disposed above the yoke  192  and which is interconnected to a second substantial portion  236  that is disposed away from the critical components of the head  140 . The lower heat sink  144  may be formed with a shape that is similar to the shape of the upper heat sink  220 . The two heat sinks  144  and  220  of the magnetic head embodiment  140  serve to provide enhanced heat dissipation from the inductive write head and provide thermal protection to the read sensor  52  and pole tip  160  structures of the magnetic head  140 .  
         [0037]     In an enhanced embodiment of the magnetic head  140 , as is best seen in  FIG. 6 , a heat sink interconnect via (not shown) may be fabricated through insulation layers that have been deposited down to the lower heat sink structure  144 . This heat sink interconnect via may be fabricated in the same via formation step in which the electrical interconnect via to the coil center tap is created. Thereafter, when the electrical interconnect  212  is electroplated, a heat sink interconnect  246  is also electroplated within the heat sink interconnect via. Then, when the upper heat sink  220  is fabricated it will be interconnected through the heat sink interconnect  246  with the lower heat sink  144  thereby providing enhanced thermal dissipation properties to the head.  
         [0038]     In an still further enhanced magnetic head embodiment, a heat sink interconnect via (not shown) may be fabricated in insulation layers of the read head, such that a heat sink interconnect  252  is fabricated within the heat sink interconnect via during the fabrication of the electrical leads for the read head sensor. This heat sink interconnect  252  is formed away from the read head components, such as the S 1  and S 2  shields, to interconnect the lower heat sink  144  with the slider base  22 . Where such a heat sink interconnect  252  is utilized, heat generated by the inductive write head can be dissipated through the lower heat sink  144  and/or the upper heat sink  220  down to the slider base  22  for further heat dissipation and thermal control of the magnetic head.  
         [0039]     The devices depicted in  FIGS. 5 and 7  include insulation layers (such as layer  94  in  FIG. 5  and layers  152  and  208  in  FIG. 7 ) that are formed between the heat sink structure and the magnetic pole from which the heat sink removes unwanted heat. It is therefore advantageous that the thickness of the insulation layers be as thin as is possible to improve the efficiency of the heat removal process of the heat sink. The insulation layers  94 ,  152  and  208  generally serve to insulate the effects of possible eddy currents within the heat sink and possible related magnetic flux flow problems within the magnetic poles that can lead to degraded device performance. However, where such problems are not significant, the insulation layers  94 ,  152  and/or  208  are not necessary, and  FIG. 8  depicts a magnetic head  260  of the present invention that is similar to the device depicted in  FIG. 7  in which the insulation layers  152  and  208  are not fabricated between the heat sinks and the magnetic poles.  
         [0040]     The alternative magnetic head  260  of the present invention, as depicted in  FIG. 8 , includes many identical structures to the magnetic head  140  depicted in  FIG. 7 , and like structures are numbered identically for ease of comprehension. As depicted in  FIG. 8 , the perpendicular magnetic head  260  includes a read head portion that is similar to the read head depicted in  FIGS. 2 and 4 . That is, it includes a first magnetic shield layer (S 1 )  40  that is formed upon a slider body  22 , a read head sensor element  52  that is disposed within insulating layers  54  and  56 , and a second magnetic shield layer (S 2 )  58  that is formed upon the insulation layer  56 . An electrical insulation layer  59  is deposited upon the S 2  shield  58 .  
         [0041]     A lower heat sink structure  144  is next fabricated upon the electrical insulation layer  59 , and insulation material such as alumina  150  is deposited, and a chemical mechanical polishing (CMP) step is performed to create a flat upper surface to the heat sink structure  144  for the continued fabrication of further magnetic head structures.  
         [0042]     A first magnetic pole structure  156 , termed a shaping pole, is next fabricated upon the heat sink  144 . Thereafter, a narrow pole tip  160  of the magnetic head is fabricated upon the first magnetic pole structure  156 . A further insulation layer  170  is next fabricated upon the pole tip  160  and shaping pole  156 , and an induction coil structure, typically comprised of copper coil turns  178 , that is formed within electrical insulation  182 , is fabricated upon the insulation layer  170 . Thereafter, a second magnetic pole  186  is fabricated above the induction coil insulation  182 . The second magnetic pole  186  includes a magnetic flux return pole tip  190  together with a yoke portion  192  that is disposed above the induction coil  178 , and which is magnetically connected through a backgap piece  196  to the shaping pole  156 . The center tap  200  of the induction coil  178  is fabricated behind the interconnection of the yoke with the backgap piece. Thereafter, an electrical insulation layer  208  is deposited, followed by a CMP step to remove insulation  208  from above the yoke  192 . A via for an electrical interconnect is created within the insulation layer  208  down to the center tap  200 , and an electrical interconnect  212  is then electroplated up within the via. Thereafter, as is described hereabove with regard to the magnetic head embodiment  140  depicted in  FIGS. 6 and 7 , an upper heat sink structure  220  is fabricated during the fabrication steps that are conducted to form the electrical lead  228  from the center tap electrical interconnect  212  to the contact pads  230  of the magnetic head. Thus, the upper heat sink  220  may be fabricated in substantially the identical manner as the heat sink  120  of magnetic head  118 . That is, in a photolithographic process in which a seed layer  230  is first deposited, and the heat sink  220  and electrical leads  228  are electroplated within photoresist trenches. The photoresist and uncovered seed layer are thereafter removed, and an encapsulation layer  231  is subsequently deposited upon the magnetic head structures.  
         [0043]     While the present invention has been shown and described with regard to certain preferred embodiments, it is to be understood that modifications in form and detail will no doubt be developed by those skilled in the art upon reviewing this disclosure. It is therefore intended that the following claims cover all such alterations and modifications that nevertheless include the true spirit and scope of the inventive features of the present invention.

Technology Category: g