Patent Publication Number: US-6987646-B2

Title: Method of making magnetic head having narrow pole tip and fine pitch coil

Description:
This is a division of application Ser. No. 09/884,574, filed Jun. 18, 2001, now U.S. Pat. No. 6,741,422. 

   BACKGROUND OF THE INVENTION 
   1 . Field of the Invention 
   The present invention relates generally to the fabrication of magnetic heads for hard disk drives, and more particularly to the fabrication of a narrow P2 pole tip and a fine pitch induction coil using a single image transfer step. 
   2 . Description of the Prior Art 
   Efforts to increase the performance characteristics of hard disk drives have focused on increasing the areal data storage density of the magnetic hard disks and increasing the data writing rate of magnetic heads in writing data to the hard disks. As will be understood from reading this detailed description, the present invention advantageously affects both of these hard disk performance characteristics. 
   One way to increase the areal data storage density is to decrease the width of the data tracks upon the hard disk media. Narrower data tracks allow for more tracks per inch (TPI) to be written on a disk, thereby increasing the areal data storage density of the disk. The well recognized method for decreasing the width of the data tracks is to decrease the width of the P2 pole tip of the magnetic head, because the width of the P2 pole tip generally determines the width of the data track that is written by the magnetic head. Prior art photolithographic techniques for fabricating P2 pole tips are currently reaching the limits of process accuracy, in that it is difficult to accurately and reliably fabricate high aspect ratio P2 pole tip trenches utilizing photolithographic techniques. Recently, high aspect ratio P2 pole tip trenches have been fabricated utilizing reactive ion etch (RIE) techniques, which have produced good results where the P2 pole tip is subsequently electroplated into the RIE created trench. The present invention is an improvement in the RIE P2 pole tip fabrication process for the fabrication of magnetic heads, as is discussed in detail below. 
   To improve the magnetic head data writing rate, prior art magnetic heads have been fabricated with higher aspect ratio induction coils. Such high aspect ratio induction coils allow for the individual induction coil turns to be spaced closer together, creating a fine pitch induction coil. Where a fine pitch induction coil is fabricated, the P2 pole yoke can be shortened, thus creating a similarly shortened magnetic flux circuit through the P1 and P2 poles, such that the data writing rate of the magnetic head is increased. 
   The present invention advantageously utilizes one dielectric layer, one RIE mask and image transfer step, and one RIE step to create both a narrow, high aspect ratio P2 pole tip and a high aspect ratio, fine pitch induction coil. In so doing, fabrication problems associated with separate RIE processes for creating a P2 pole tip and for creating a fine pitch induction coil are avoided, and the fabrication of an improved magnetic head is simplified. 
   SUMMARY OF THE INVENTION 
   The magnetic head of the present invention includes a narrow, high aspect ratio P2 pole tip and a high aspect ratio, fine pitch induction coil. Electroplating trenches for the P2 pole tip and the induction coil are fabricated in a single RIE process step, and the P2 pole tip and the induction coil are thereafter separately plated up into their respective trenches to complete the fabrication of these structures. 
   Briefly, following the fabrication of a P1 pole and the deposition of an insulation layer thereon, a patterned P2 pole tip seed layer is deposited. Significantly, the pole tip seed layer is not deposited beneath the induction coil area of the magnetic head. A dielectric layer is next deposited and a patterned RIE etching mask is fabricated upon the dielectric layer. The etching mask pattern includes both a P2 pole tip trench opening and an induction coil trench opening. Thereafter, in a single RIE etching step, the P2 pole tip trench is etched through the dielectric material down to the seed layer, and the induction coil trench is etched through the dielectric material down to the insulation layer. The P2 pole tip is then electroplated up into its trench, and no electroplating occurs within the induction coil trench because no seed layer has been yet deposited therein. Following the electroplating of the P2 pole tip, an induction coil seed layer is deposited upon the wafer surface and specifically down into the induction coil trench. Thereafter, the induction coil is electroplated up into the induction coil trench. A chemical mechanical polishing (CMP) step is next conducted to remove the excess induction coil material and the RIE etching mask. Thereafter, a patterned insulation layer is deposited upon the induction coil, which is followed by the fabrication of a P2 pole yoke thereupon. Further fabrication steps as are known to those skilled in the art are thereafter accomplished to complete the magnetic head of the present invention. 
   It is an advantage of the magnetic head of the present invention that it includes a narrow, high aspect ratio P2 pole tip and a high aspect ratio, fine pitch induction coil. 
   It is another advantage of the magnetic head of the present invention that the P2 pole tip and the induction coil are fabricated utilizing a single RIE etching mask. 
   It is a further advantage of the magnetic head of the present invention that it includes a narrow, high aspect ratio P2 pole tip and a high aspect ratio, fine pitch induction coil that are fabricated in a single dielectric layer. 
   It is an advantage of the hard disk drive of the present invention that it has an increased areal data storage density and an increased data writing rate. 
   It is another advantage of the hard disk drive of the present invention that it includes a magnetic head of the present invention having a narrow, high aspect ratio P2 pole tip and a high aspect ratio, fine pitch induction coil. 
   It is another advantage of the hard disk drive of the present invention that it includes a magnetic head of the present invention wherein the P2 pole tip and the induction coil are fabricated utilizing a single RIE etching mask. 
   It is a further advantage of the hard disk drive of the present invention that it includes a magnetic head of the present invention that includes a narrow, high aspect ratio P2 pole tip and a high aspect ratio, fine pitch induction coil that are fabricated in a single dielectric layer. 
   It is an advantage of the fabrication method of the present invention that a narrow, high aspect ratio P2 pole tip and a high aspect ratio, fine pitch induction coil are fabricated within a single dielectric material layer. 
   It is another advantage of the method for fabricating a magnetic head of the present invention that the P2 pole tip trench and the induction coil trench are fabricated in a single RIE etching step. 
   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 
       FIG. 1  is a top plan view of a hard disk drive including a magnetic head of the present invention; 
       FIG. 2  is a top plan view generally depicting a magnetic head fabricated on a wafer which serves as a starting point for the description of the present invention; 
       FIGS. 3–7  are side cross-sectional views taken along lines  3 — 3  of  FIG. 2  that depicts further fabrication steps of the magnetic head of the present invention; 
       FIG. 8  is a top plan view depicting the P2 pole tip and induction coil trenches created in a fabrication step of the magnetic head of the present invention; 
       FIGS. 9–16  depict further fabrication steps of the magnetic head of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     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 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 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 . 
   As is well known to those skilled in the art typical magnetic head fabrication steps generally include the deposition and patterning of various thin film layers to fabricate a read head, followed by the further deposition and patterning of various thin film layers upon the read head to fabricate a write head. The present invention relates to the fabrication of a write head, and therefore a magnetic head of the present invention may include most, if not all, of the various read head configurations as are generally known to those skilled in the art. Therefore, the description of the present invention commences with write head fabrication steps upon a wafer after the fabrication of the read head component layers. 
     FIG. 2  is a generalized top plan view of a typical magnetic head  40  that serves as an orientation figure for this detailed description. As depicted in  FIG. 2 , a typical write head portion  44  of a magnetic head generally includes a P1 pole layer  48  that is composed of a ferromagnetic material such as NiFe, a flat, spiral induction coil  50  that is formed in a generally oval area  52  above the P1 pole and includes electrical leads  54  and  56 , a narrow P2 pole tip  60  that is formed above portions of the P1 pole, and a P2 pole yoke  66  that is joined to the P2 pole tip  60  and is generally formed above the induction coil. The top of the P2 yoke  66  and the P1 pole  48  are joined together in a back gap area  70  that is generally centrally located within the induction coil area  52 , and the P2 pole tip  60  is separated from the P1 pole  48  by a write gap layer (not shown in  FIG. 2 ). These general features of a typical write head portion of a magnetic head  40  are found in the present invention are more fully described in the following detailed description of the present invention which focuses on the fabrication of the P2 pole tip  60  and the induction coil  50 . 
     FIG. 3  is a side cross-sectional view of a fabrication step of a magnetic head  20  of the present invention which serves as a starting point for the detailed description, and  FIG. 3  is taken along lines  3 — 3  of  FIG. 2 . In this initial fabrication step depicted in  FIG. 3 , the P1 pole  48  has been fabricated and a write gap layer  84  has been deposited upon the P1 pole. A typical write gap layer  84  is composed of an electrically and magnetically nonconductive material, such as alumina. Thereafter, a P2 pole tip magnetic seed layer  88  of the present invention is deposited upon the write gap layer  84 . Typically, the P2 pole tip seed layer is comprised of NiFe and serves as an initial electrical plating surface in a subsequent P2 pole tip electroplating process described herebelow. Thereafter, as depicted in  FIG. 4  portions of the NiFe seed layer are removed in a patterning step from the area  52  in which the induction coils will subsequently be fabricated. As depicted in  FIG. 4  portions  92  of the NiFe seed layer  88  may remain in the field away from the induction coil region. As a result of the seed layer patterning step, the alumina surface is exposed in the coil region  52 , whereas a portion of the seed layer  96  remains in the P2 pole tip region. Thereafter, as depicted in  FIG. 4 , a further patterning and etching step is conducted to create a back gap hole  100  in the exposed write gap layer  84  within the induction coil area  52  to expose the surface of the P1 pole  48 , such that a later fabricated back gap element will make magnetic connection with the P1 pole  48 , as described in detail herebelow. Thereafter, as depicted in  FIG. 5 , a layer of dielectric material  108  is deposited across the surface of the wafer and down into the back gap hole  100 . It is important that the material comprising the dielectric layer be susceptible to a reactive ion etch process (as described below) and suitable dielectric materials include SiO 2  where a fluorine RIE process is conducted, or an organic polymer may be used where an oxygen RIE process is conducted. 
   Thereafter, as depicted in  FIG. 6 , a patterned RIE etch mask  112  of the present invention is fabricated upon the dielectric layer  108 . A significant feature of the present invention is that the RIE mask is patterned to include openings  114 ,  116  and  118  for the P2 pole tip trench configuration and the induction coil trench configuration, as well as the back gap piece, as is next described. For a fluorine RIE process a suitable etching mask  112  may be composed of a thin layer of NiFe or alumina, whereas for an oxygen RIE process the mask may be composed of SiO 2 , Ta 2 O 5 , titanium, NiFe, alumina or other materials as are known to those skilled in the art. 
   Following the fabrication of the patterned RIE mask  112 , an RIE process step is conducted, in which trenches are etched through the mask openings into the dielectric material.  FIG. 7  is a cross-sectional view of the trench pattern of the present invention, and  FIG. 8  is a top plan view of the trench pattern depicted in  FIG. 7 . Therefore, as is depicted in  FIGS. 7 and 8 , the RIE trenches include the P2 pole tip trench  120  that is etched through opening  114  down to the patterned NiFe seed layer  96 , the spiral induction coil trench  128  that is etched through opening  116  down to the write gap layer  84 , and the back gap trench  134  that is etched through opening  118  down through the back gap hole  100  to the P1 pole surface  48 . It is noteworthy that the RIE trenches  120 ,  128  and  134  all have essentially the same depth, that being the thickness of the dielectric layer  108 . 
   An electroplating process for the P2 pole tip and back gap piece is next conducted. Specifically, as depicted in  FIG. 9 , an electrical potential is set up through the exposed seed layer  96  of the P2 pole tip, as well as the exposed P1 pole surface  48 . The P2 pole tip  140  plates up into the P2 pole tip trench  120  and the back gap piece  148  simultaneously plates up into the back gap trench  134 . Significantly, plating does not occur within the induction coil trenches  128  because there is no seed layer within the induction coil trenches to cause electroplating therewithin. The electroplating step of the P2 pole tip and back gap piece is conducted until the trenches are fully plated up. 
   The fabrication of the copper induction coil is next commenced by the sputter deposition of a copper seed layer across the surface of the wafer. As depicted in  FIG. 10 , the copper seed layer  160  is deposited through the openings  116  into the induction coil trenches  128  as well as across the surface of the wafer, including the plated up P2 pole tip  140  and back gap piece  148 . Thereafter, as depicted in  FIG. 11 , a copper electroplating process is conducted. A copper deposition  168  is formed upon the upper seed layer  160 , and the copper seed layer  160  within the induction coil trenches  128  facilitates the electroplating of copper through the openings  116  into the trenches  128  to plate up the trenches and create the copper induction coil  170 . Where sufficient electroplating power or other factors are of concern, the copper seed layer may be patterned such that the copper seed layer is only deposited in the necessary induction coil related areas. Thereafter, as depicted in  FIG. 12 , a chemical mechanical polishing (CMP) step is conducted to remove the excess copper  168  as well as the upper portions of the copper seed layer  160  and the RIE mask layer  112  to create a planar surface  180 . As is further depicted in  FIG. 12 , a patterned electrical insulation layer  188  is thereafter deposited on top of the induction coil  170  to prevent coil shorting, and as is also depicted in  FIG. 12 , a patterned P2 yoke element  192  (sometimes referred to as a P3 pole) is fabricated on top of the insulation layer  188 . The P2 yoke  192  is fabricated to make contact with both the P2 pole tip  140  and the back gap piece  148 , such that magnetic flux will flow from the P2 yoke  192 , through the back gap piece  148 , through the P1 pole  48  and across the write gap layer  84  to the P2 pole tip  140  and to the P2 yoke  192 . Thereafter, following further magnetic pole fabrication steps, including the fabrication of the induction coil electrical lead  56 , as are known to those skilled in the art, an encapsulation layer  200  is deposited to complete the wafer level fabrication of the magnetic head  20  which is suitable for use in the disk drive  10 . 
   In the preferred embodiment of the present invention, a P1 pole notching step is conducted preferably following the fabrication of the P2 yoke and before encapsulation depicted in  FIG. 12 . Specifically,  FIG. 13  depicts another patterned RIE etching mask  210  that is fabricated to include an opening  214  to expose the area around the P2 pole tip  140 , and  FIG. 14  is an end cross-sectional view of the head taken along lines  14 — 14  of  FIG. 13 . Another RIE etching process is then conducted, as depicted in  FIG. 15 , to create a trench  218  within the etchable dielectric material proximate the P2 pole tip  140 . As is next depicted in  FIG. 16 , an ion milling process utilizing argon, or other ion milling species as are known to those skilled in the art, is conducted to remove portions of the NiFe seed layer  96 , write gap layer  84  and a portion of the P1 pole  48  proximate the P2 pole tip  140 , such that P1 pole notches  220  are achieved. Encapsulation of the notched head then follows, as is known to those skilled in the art. 
   It is therefore to be understood that a significant feature of the present invention is the utilization of a single RIE etching step to simultaneously create the P2 pole tip trench, the induction coil trench and the back gap trench. The prior deposition of the patterned P2 pole tip seed layer  96  allows for the separate electroplating of the P2 pole tip from the induction coil  170 . Thereafter, a subsequent deposition of the copper seed layer into the preexisting induction coil trench facilitates the electroplating of the induction coil into the trench. The use of the single RIE process to simultaneously create both the P2 pole tip trench, the back gap trench and the induction coil trench saves time and expense in the magnetic head fabrication process. Additionally, fabrication difficulties which would result from depositing two or more separate RIE etchable dielectric layers for separate P2 pole tip and induction coil fabrication steps, as well as the difficulties of the alignment of the induction coils with the P2 magnetic pole tip and the back gap piece is avoided. The use of RIE process techniques facilitates the fabrication of fine pitched induction coils as well as narrower P2 pole tips than are typically accomplished utilizing photolithographic techniques in which high aspect ratio trenches for the P2 pole tip and the induction coil are difficult to reliably fabricate. A hard disk drive having a magnetic head of the present invention can be fabricated with increased areal data storage density due to the present invention&#39;s simplified fabrication of a narrower P2 pole tip, which creates narrower data tracks and leads to more tracks per inch written on the magnetic disk media of the hard disk drive. The high aspect ratio, fine pitch induction coil leads to increased data writing rates for the hard disk drive, as will be understood by those skilled in the art. 
   While the present invention has been shown and described with regard to certain preferred embodiments, it is to be understood that those skilled in the art will no doubt develop certain alterations and modifications in form and detail having read the preceding description. It is therefore intended that the following claims cover all such alterations and modifications that nevertheless include the true spirit and scope of the invention.