Abstract:
A magnetic head according to one embodiment includes a first magnetic shield; a first insulation layer disposed above said first magnetic shield; a plurality of sensor layers disposed above said first insulation layer; two electrical leads overlying a majority of a surface of the sensor layers, the electrical leads being formed of a magnetic material and serving as a second magnetic shield; and a read width insulation member disposed above said sensor layers and between said two electrically conductive members, the read width insulation members lying in a common plane with the electrically conductive members, the common plane being oriented parallel to a plane of deposition of the read width insulation member. Other systems and methods are also presented.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. Pat. No. 11/638,974, filed Dec. 14, 2006, and which is herein incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to read head portions of magnetic heads for hard disk drives, and more particularly to lead overlaid read heads wherein the electrical leads and second magnetic shield are combined. 
         [0004]    2. Description of the Prior Art 
         [0005]    Increasing the performance of hard disk drives may be achieved by increasing the areal data storage density of the magnetic hard disk. This can be accomplished by reducing the written data track width, such that more tracks per inch can be written on the disk. To read data from a disk with a reduced track width, it is necessary to develop read heads with a sufficiently narrow read width, such that the narrow data tracks can be accurately read, and unwanted magnetic field interference from adjacent data tracks is substantially eliminated when reading a narrow data track. 
         [0006]    The standard prior art read head elements include a plurality of thin film layers that are deposited and fabricated to produce a GMR read head, as is known to those skilled in the art. Significantly, where the width of the thin film layers that comprise the GMR read head sensor are reduced below certain values, the magnetic properties of the layers are substantially compromised. To overcome this problem, GMR read heads have been developed in which the thin film layers have an ample width and the electrical leads are overlaid on top of portions of the thin film layers. This lead overlaid configuration has the effect of creating an active read head sensor region having a read width that is less than the entire width of the deposited sensor layers, such that the magnetic properties of the thin film layers can be preserved. Thus, in the lead overlaid GMR read heads of the prior art, the active magnetic layer portions of the sensor exist between the inner ends of the electrical leads. 
         [0007]    Increases in the areal data storage density of magnetic disks are also achieved by increasing the number of bits per inch on the data tracks of the disk, and this is accomplished by reducing the in-track size of the data bits. To read such reduced size data bits, it is necessary to reduce the read gap of the read sensor, where the read gap is defined as the distance between the magnetic shields that are fabricated beneath and above the sensor layers. 
         [0008]    To improve the performance characteristics of such lead overlaid read heads, it is therefore desirable to decrease the read width between the inner ends of the overlaid leads and to decrease the read gap between the magnetic shields. The present invention addresses these issues. 
       SUMMARY 
       [0009]    A magnetic head according to one embodiment includes a first magnetic shield; a first insulation layer disposed above said first magnetic shield; a plurality of sensor layers disposed above said first insulation layer; two electrical leads overlying a majority of a surface of the sensor layers, the electrical leads being formed of a magnetic material and serving as a second magnetic shield; and a read width insulation member disposed above said sensor layers and between said two electrically conductive members, the read width insulation members lying in a common plane with the electrically conductive members, the common plane being oriented parallel to a plane of deposition of the read width insulation member. 
         [0010]    A method for fabricating a magnetic head according to another embodiment includes fabricating a first magnetic shield above a wafer substrate; fabricating a first insulation layer above said first magnetic shield; fabricating a plurality of sensor layers above said first insulation layer; fabricating a read width insulation member above said sensor layers; and depositing electrical lead material above said sensor layers and above and in a same deposition plane as said read width insulation member, the electrical lead material overlying a majority of a surface of the sensor layers, the electrical lead material comprising a magnetic material, the electrical lead material serving as a second magnetic shield. 
         [0011]    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 drawings. 
     
    
     
       IN THE DRAWINGS 
         [0012]      FIG. 1  is a top plan view depicting a hard disk drive having a magnetic head of the present invention; 
           [0013]      FIG. 2  is a side elevational view of a prior art lead overlaid read head portion of a magnetic head; 
           [0014]      FIG. 3  is a side elevational view of a first embodiment of a lead overlaid read head portion of a magnetic head of the present invention; 
           [0015]      FIGS. 4-8  are side elevational views of fabrication steps for lead overlaid read head portion of a magnetic head of the present invention; 
           [0016]      FIG. 9  is a side elevational view of an alternative embodiment of a lead overlaid read head portion of a magnetic head of the present invention; and 
           [0017]      FIG. 10  is a side elevational view of another embodiment of a lead overlaid read head portion of a magnetic head of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]      FIG. 1  is a top plan view that depicts significant components of a hard disk drive which includes the magnetic head of the present invention. The hard disk drive  10  includes a magnetic media hard disk  12  that is rotatably mounted upon a motorized spindle  14 . An actuator arm  16  is pivotally mounted within the hard disk drive  10  with a magnetic head  20  of the present invention disposed upon a distal end  22  of the actuator arm  16 . A typical hard disk drive  10  may include a plurality of disks  12  that are rotatably mounted upon the spindle  14  and a plurality of actuator arms  16  having a magnetic head  20  mounted upon the distal end  22  of each of the actuator arms. As is well known to those skilled in the art, when the hard disk drive  10  is operated, the hard disk  12  rotates upon the spindle  14  and the magnetic head  20  acts as an air bearing slider that is adapted for flying above the surface of the rotating disk. The slider includes a substrate base upon which the various layers and structures that form the magnetic head are fabricated. Such heads are fabricated in large quantities upon a wafer substrate and subsequently sliced into discrete magnetic heads  20 . 
         [0019]    One way to increase the areal data storage density of a hard disk  12  is to narrow the track width of the data tracks written on the hard disk, such that more tracks per inch can be written on the disk. To write data in narrower tracks it is necessary to develop the write head components of magnetic heads with a narrower written track width. Correspondingly. it is also necessary to develop read head components of such magnetic heads  20  having narrowed active read widths, such that the narrow data tracks can be read and side reading from adjacent data tracks is minimized. However, as is known in the prior art performance limitations exist with regard to the width of the thin film layers that form the read head active components of GMR read heads. That is, the desirable magnetic properties of the thin film sensor layers of the read head arc adversely affected where the width of the sensor layers is decreased below certain values. A prior art attempt to overcome this limitation is the lead overlaid read head configuration that is depicted in  FIG. 2 , and next described. 
         [0020]      FIG. 2  is a side cross-sectional view of a prior art electrical lead overlaid GMR read head  36  portion of a magnetic head  40 . As depicted therein, the prior art lead overlaid read head  36  generally includes a substrate base  42  that constitutes the wafer material above or upon which the magnetic head is fabricated, such as alumina titanium carbide. A first magnetic shield  44  is fabricated on an undercoat layer  43  that is deposited above or upon the substrate, and an insulation layer  46 , typically composed of aluminum oxide, is fabricated above or upon the magnetic shield  44 . A series of thin film sensor layers are sequentially deposited above or upon the insulation layer  46 . A variety of thin film sensor layers are known in the prior art to fabricate such GMR read heads, and, for the purposes of the present invention the layers generally include an antiferromagnetic layer  54 , a pinned magnetic layer  58  that is deposited above or upon the antiferromagnetic layer  54 , a spacer layer  64  that is deposited above or upon the pinned magnetic layer  58 , a free magnetic layer  68  that is deposited above or upon the spacer layer  64  and a cap layer  72  that is deposited above or upon the free magnetic layer  68 . Typically, the antiferromagnetic layer  54  may be composed of PtMn, the pinned magnetic layer  58  may be composed of CoFe, the spacer layer  64  may be composed of Cu, the free magnetic layer  68  may be composed of CoFe and the cap layer  72  may be composed of Ta. 
         [0021]    Following the deposition of the read head sensor layers  54 - 72 , a patterned etching process is conducted such that only central regions  80  of the sensor layers  54 - 72  remain. Thereafter, a thin layer  84  of electrical insulation is deposited in the side regions along side the central sensor region  80 , and hard bias elements  88  are deposited on the insulation layer  84  on each side of the central sensor region  80 . Following the deposition of the hard bias elements  88 , electrical lead elements  94  are fabricated on top of the hard bias elements  88 . As depicted in  FIG. 2 , inner ends  96  of the leads  94  are overlaid on top of outer portions  100  of the layers  54 - 72  of the central read head sensor region  80 . A central portion  102  of the sensor layers  80  is not covered by the inner ends  96  of the leads  94 . A second insulation layer  104  is fabricated on top of the electrical leads  94  and cap layer  72 , followed by the fabrication of a second magnetic shield  108 , and further components  112  (not shown in detail) that are well known to those skilled in the art are thereafter fabricated, to ultimately create a complete magnetic head. 
         [0022]    A significant feature of the prior art lead overlaid GMR read head  36  depicted in  FIG. 2  is that the portion of the central sensor region  80 , which substantially defines the read width W of the read head  36 , is the central portion  102  of the central sensor region  80  that is disposed between the inner ends  96  of the electrical leads  94 . That is, because the electrical current flows through the read head sensor layers between the electrical leads  94 , the active portion of the sensor layers generally comprises the read width W. between the inner ends  96  of the electrical leads  94 . The outer portions  100  of the read head layers disposed beneath the overlaid inner ends  96  of the electrical leads  94  are generally passive in that significant electrical current between the electrical leads  94  does not pass through them. 
         [0023]    The read gap of the prior art magnetic head is defined as the distance between the first and second magnetic shields  44  and  108  respectively. As can be seen in  FIG. 2 , this read gap includes the thickness of the first insulation gap layer, the sensor layets and the second insulation gap layer. Where the inner ends of the overlaid electrical leads are placed close together, as is desired to produce a narrow read width, the thickness of the second gap layer must generally approximate the thickness of the electrical leads to avoid electrical shorts to the second magnetic shield. 
         [0024]    To respond to higher data density disks it is necessary to reduce the read width of the magnetic head without increasing signal noise and side-reading effects from adjacent data tracks. Also, it is desirable to reduce the read gap such that higher density data tracks can be accurately read without increased signal noise from in-track data bits on the data track that are disposed adjacent to the data bit being read. 
         [0025]    A first magnetic head embodiment of the present invention  110 , which is suitable for use as the magnetic head  20  of the disk drive  10  of  FIG. 1 , having a lead overlaid read head  120  of the present invention is depicted in  FIG. 3 . For ease of comprehension, similar structures of the present invention and prior art are identically numbered. As depicted in  FIG. 3 , the read head  120  includes a GMR read head thin film sensor element  80 , as well as the insulation layer  84  and the hard bias elements  88 . A significant feature of the read head  120  is the fabrication of a separate, centrally located read width electrical insulation member  128  that is disposed between two overlaid electrical leads  134  and  138 , where the insulation member  128  is centrally disposed above or upon the thin film sensor element  80 . A second significant feature of the read head  120  is that the leads  134  and  138  are fabricated from a magnetic shield material such as NiFe, and preferably though not necessarily Permalloy (80/20 NiFe). An electrical insulation layer  140  is fabricated above or upon the upper surfaces  142  of the electrical leads  134 ,  138  and the upper surface  144  of the electrical insulator  128 . 
         [0026]    As with the prior art lead overlaid read head sensor depicted in  FIG. 2  and described hereabove, electrical current  146  will flow through an electrical lead  134 , through the sensor layers  80  due to the electrical insulation member  128  and through the other electrical lead  138 . As a result, the effective read width W of the read head  120  is generally approximately equal to the width S of the electrical insulator member  128 , plus some characteristic additional width on each side of the electrical insulation member  128  depending on the relative electrical resistivities of the sensor layers and the leads. Therefore, controlled fabrication of the width S of the insulation member  128 , and particularly a reduction in the width S, results in the reduction in the read width W of the read head  120 , resulting in a magnetic head  110  that is suitable for reading narrow track widths of a higher density data disk. 
         [0027]    Another significant feature of the read head  120  is that the electrical leads  134 ,  138  also serve as the second magnetic shield, in that they are comprised of a magnetic shield material such as NiFe. Significantly, there is no insulation layer, corresponding to the second insulation layer  104  of the prior art magnetic head depicted in  FIG. 2 , between the second magnetic shield  134 ,  138  and the sensor layers  58 - 72  of the read head  120 . As a result, the read gap distance between the first magnetic shield  44  and the second magnetic shield (the electrical leads  134 ,  138 ) is reduced as compared to the prior art because the second insulation layer  104  (see  FIG. 2 ) is not required to be fabricated between the two magnetic shields  44  and  134 ,  138 . The reduction of the read gap increases the in-track reading sensitivity of the read head  120 . In this regard, the read head  120  is also suitable for higher density magnetic disks having an increased bits per inch data track density. A method for fabricating the read head  120  of the present invention is next described with the aid of  FIGS. 4-8 . 
         [0028]      FIG. 4  represents a starting point for a description of the fabrication method of the present invention. As depicted therein, the undercoat layer  43 , the first magnetic shield  44  and the first insulation layer  46  have been fabricated above or upon a magnetic head substrate  42 . Thereafter, the various layers that comprise the GMR sensor layers  54 - 72  have been deposited and patterned to create the central sensor layer structure  80 . Thereafter, a thin layer  84  of electrical insulation material, such as alumina, is deposited along side the central sensor  80 , and hard bias elements  88  are fabricated above or upon the insulation layer  84 . The thin insulation layer  84  is preferably, though not necessarily, fabricated using an atomic layer deposition (ALD) method as is known to those skilled in the art. It is therefore to be understood that this stage of read head fabrication is substantially identical to that depicted in  FIG. 2 , and well understood by those skilled in the art. 
         [0029]    Thereafter, as depicted in  FIG. 5 , the read width electrical insulation member  128  is fabricated above or upon the central sensor  80 . It is desirable that the insulation member  128  be fabricated centrally between the hard bias elements  88 , and that the height (referred to as stripe height (not shown)) of the insulation member  128  extend at least as far as the stripe height of the sensor element  80 , as will he understood by those skilled in the art. It is also desirable that the width S of the insulator member  128  be controllably narrow, because the read width W of the magnetic head is significantly, though not entirely, determined by the width S of the insulator member  128 . 
         [0030]    Various fabrication methods, as are known to those skilled in the art, may be utilized to fabricate the thin insulation member  128 . For example, one such insulation member fabrication method includes the fabrication of a vertical photoresist wall at the desired location of the insulation member  128 . Thereafter, utilizing a deposition process such as ALD, a layer of insulation member material is deposited above or upon the horizontal surfaces and on the vertical photoresist wall. Then, using a reactive ion etch (RIE) process, the insulation layer material is removed; however, due to the very directional nature of the RIE process, the insulation material is removed from the horizontal surfaces, whereas the insulation material deposited on the vertical wall of the photoresist remains. Thereafter, upon removal of the photoresist, a thin, vertical, insulation member  128  remains having a width S that is approximately equal to the thickness of the ALD deposited layer. Using this fabrication method a high aspect ratio electrical insulation member  128  comprised of a material such as alumina is fabricated, and the width S can be controlled to dimensions as low as 1-40 nm, where 1 nm is approximately the minimum desired width due to unwanted electrical tunneling of electrons through a thin film alumina layer of approximately 1 nm or less, as is well known to those skilled in the art. 
         [0031]    Thereafter, as depicted in  FIG. 6 , the electrical lead material  130  is deposited in an appropriate pattern upon the device, such that the electrical lead material  130  is disposed at side surfaces  154  of the insulation member  128 . As indicated hereabove, the electrical leads are comprised of a magnetic material such as NiFe, and they may be sputter deposited or electroplated in a suitable electrical lead pattern. As depicted in  FIG. 6 , where the electrical lead material is sputter deposited, a quantity  160  of electrical lead material will be deposited above or upon the electrical insulation member  128 . 
         [0032]    Thereafter, as depicted  FIG. 7 , following the deposition of the electrical lead material  130 , a chemical mechanical polishing (CMP) step is undertaken to remove the extra electrical lead material  160  and to create the top surfaces  142  of the leads and expose the top surface  144  of the electrical insulation member  128 . It is important that the top surface  144  of the electrical insulation member  128  be exposed, such that any possible electrical shorts between the electrical leads  134 ,  138  are prevented by the insulation member  128 , and sensor current between the leads is thereby caused to pass through the central sensor  80 . 
         [0033]    As depicted in  FIG. 8 , after the leads  134 ,  138  are fabricated, electrical insulation material  164 , such as alumina, is next deposited across the top surfaces  142  of the electrical leads and the top surface  144  of the electrical insulation member  128 , such that the electrical leads  134  and  138  are covered by insulation material  164  to prevent electrical shorts. The electrical leads  134 ,  138 , being comprised of a magnetic material, also function as the second magnetic shield of the read head  120 , and serve to prevent unwanted side reading and noise from adjacent data tracks. Further magnetic head components  166  (not shown in detail), such as write head components, are then fabricated above or upon the insulation layer  164  in a plurality of well known subsequent steps to ultimately create a complete magnetic head  110 . 
         [0034]    Alternatively, as depicted in  FIG. 9 , an alternative read head embodiment  170  can be created by deposition of a second layer of magnetic material  168 , such as NiFe, above the insulation material layer  164  to provide a more robust magnetic shielding for the read head sensor. However, the primary magnetic shielding, which essentially controls the read gap distance, is provided by the electrical leads  134 ,  138  (second magnetic shield) that are comprised of magnetic material. 
         [0035]      FIG. 10  depicts an alternative read head embodiment  180  of the present invention having many similar structures to the read head  120  depicted in  FIGS. 3 and 8 , and such similar structural elements are identically numbered for ease of comprehension. As depicted in  FIG. 10 , the significant difference in the magnetic head  180  is that outer portions  184  of the electrical leads are formed from a non-magnetic, better electrical conductor than NiFe, such as Rh. The outer portions  184  of the electrical leads are fabricated above or upon the NiFe magnetic electrical leads  134 ,  138  following the CMP step depicted in  FIG. 7 . Such outer electrical leads  184 , being composed of a non-magnetic electrical conductor, are desirable to reduce unwanted signal noise that can be created if the entire electrical lead structure of the read head is comprised of a magnetic material. As with the preceding read head embodiment  120 , the read head  180  produces reduced noise and reduced side reading. 
         [0036]    It is therefore to be understood that the read width W of the magnetic head of the present invention can be effectively reduced to approximately the width S of the insulation member  128 , plus some characteristic additional width on each side of the insulation member  128  depending on the relative electrical resistivities of the sensor layers and the leads, utilizing the electrical lead overlaid fabrication method of the present invention. Unwanted magnetic noise and side reading can be likewise reduced by fabricating the overlaid leads from a magnetic material such as NiFe. This places the magnetic shield closer to the sensor layers  80 , and also reduces the read gap of the read head. 
         [0037]    Significant features of the present invention are the reduced read width and reduced read gap of the read head, which result in reduced signal noise. Higher density data disks may be effectively read with the read head sensor of the magnetic head of the present invention. The present invention is intended to apply to various types and configurations of GMR read heads that include various numbers and types of thin film layers to provide improved read head characteristics for lead overlaid configurations. Therefore, while the present invention has been shown and described with regard to certain preferred embodiments, it will be understood that those skilled in the art will no doubt develop certain alterations and modifications thereto which nevertheless include the true spirit and scope of the invention. It is therefore intended that the following claims cover all such alterations and modifications.