Patent Publication Number: US-2007121251-A1

Title: Method of manufacturing head, head, and disk driving device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2005-345911, filed Nov. 30, 2005, the entire contents of which are incorporated herein by reference.  
     BACKGROUND  
      1. Field  
      One embodiment of the invention relates to a method of manufacturing a head used in a disk driving device such as a magnetic disk driving device, a head manufactured by this manufacturing method, and a disk driving device comprising this head.  
      2. Description of the Related Art  
      A disk driving device, for example, a magnetic disk drive, comprises a magnetic disk disposed in a case, a spindle motor that supports and rotationally drives the magnetic disk, a magnetic head that reads and writes information from and to the magnetic disk, and a carriage assembly that supports the magnetic head so that the magnetic head is movable with respect to the magnetic disk. The carriage assembly comprises a pivotably supported arm and a suspension extending from the arm. The magnetic head is supported at an extending end of the suspension. The magnetic head has a slider attached to the suspension and a head portion provided in the slider. The head portion includes a reading element and a writing element.  
      The slider has a surface lying opposite a recording surface of the magnetic head, that is, ABS (Air Bearing Surface). A negative pressure cavity is formed in the opposite surface of the slider as a negative pressure generating section that generates a negative pressure. A predetermined head load acting toward a magnetic recording layer of the magnetic disk is imposed on the slider by the suspension. While the magnetic disk drive is in operation, air currents are generated between the rotating magnetic disk and the slider. The opposite surface of the slider is subjected to a positive pressure generated by the pad and to the negative pressure generated by the negative pressure cavity. By balancing the force applied by the air currents with the head load, the slider floats while maintaining a predetermined gap from the magnetic disk recording surface. This gap needs to be substantially equal at every radial position on the magnetic disk.  
      Exerting a negative pressure on the slider improves the characteristics of the slider. The improved characteristics allow a reduction in a margin (floating margin) for reduced pressure, error sensitivity, shock, and the like. This enables a normal magnetic spacing to be reduced to improve recording density.  
      The negative pressure is generated when air having passed through a thin air channel flows into a wider air channel. To achieve this, a protrusion is formed upstream of the vicinity of center of ABS of the slider so as to form a recessed portion that generates a negative pressure in the vicinity of center of ABS, that is, a negative pressure cavity.  
      The slider that generates a negative pressure is formed by such a removing processing as rests a protrusion on ABS. Such a slider has a complicated shape and thus cannot be produced simply by normal machining such as milling or grinding. To provide desired shapes, the slider is produced by removing processing such as ion milling or reactive ion etching (RIE) using masks obtained by patterning photo resist, as protective films.  
      As disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication Nos. 10-177947, 2003-188088, and 2001-325707, a protrusion is produced on ABS by a process of photo resist patterning, removing processing, and photo resist removal. ABS of the desired shape is produced by repeating these processes of producing a protrusion a number of times with mask shape and removing processing depth varied.  
      In recent years, the improved recording density has reduced the size of sliders, and products such as what is called pico sliders and femto sliders have been developed. The reduced size of the slider reduces the width of the protrusion formed on ABS. However, an attempt to form a thin protruding pattern results in a thin mask pattern, which makes processing of the thin protruding pattern difficult. This is because the thin mask pattern makes the mask likely to be peeled off. If the mask is peeled off before or during removing processing, parts to be protected are exposed during the removing processing, preventing the desired shape from being obtained. The peeled-off mask may re-adhere to the machined surface. In this case, the mask protects undesired areas to prevent the desired shape from being obtained after the removing processing.  
      The mask size is limited and the minimum width is 30 μm. When such a mask is used, the disk opposite surface of the slider has a minimum pattern width of 30 μm. The requirement for the slider pattern to have a width of at least 30 μm has reduced the degree of freedom of design to degrade the characteristics of the slider. The absolute value of a negative pressure generated by the slider increases consistently with the area of the negative pressure generating section. Thus, the larger width of protrusion on ABS reduces the area of the negative pressure generating section. This degrades the head characteristics. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
      A general architecture that implements the various feature of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention.  
       FIG. 1  is an exemplary plan view showing a hard disk drive (hereinafter referred to as an HDD) according to a first embodiment of the present invention;  
       FIG. 2  is an exemplary enlarged side view showing a magnetic head portion of the HDD;  
       FIG. 3  is an exemplary perspective view showing a disk opposite surface side of a slider in the magnetic head;  
       FIGS. 4A and 4B  are an exemplary plan view showing the disk opposite surface side of the slider and an exemplary diagram showing patterns corresponding to respective heights;  
       FIG. 5  is an exemplary sectional view showing the slider and taken along line V-V in  FIG. 4 ;  
       FIG. 6  is an exemplary perspective view showing a recess and protrusion structure manufactured by a basic manufacturing method according to the first embodiment;  
       FIG. 7  is an exemplary plan view showing a manufacturing step of the basic method;  
       FIG. 8  is an exemplary plan view showing a manufacturing step of the basic method;  
       FIGS. 9A, 9B ,  9 C,  9 D,  9 E, and  9 F are exemplary sectional views showing respective manufacturing steps of the basic method;  
       FIG. 10  is an exemplary plan view of a slider showing a first removing processing of the manufacturing method according to the first embodiment;  
       FIG. 11  is an exemplary plan view of the slider showing a second removing processing of the manufacturing method according to the first embodiment;  
       FIG. 12  is an exemplary plan view of the slider showing a third removing processing of the manufacturing method according to the first embodiment;  
       FIGS. 13A, 13B ,  13 C,  13 D, and  13 E are exemplary plan views showing plural types of sliders manufactured by the manufacturing method according to the first embodiment and plural types of sliders according to comparative examples;  
       FIG. 14  is an exemplary diagram showing the relationship between the width of protruding portion of each of the plural types of sliders and a negative pressure generated;  
       FIG. 15  is an exemplary perspective view showing a magnetic head according to a second embodiment of the present invention;  
       FIGS. 16A, 16B , and  16 C are exemplary plan views showing respective steps of manufacturing a magnetic head according to the second embodiment;  
       FIG. 17  is an exemplary perspective view showing a magnetic head according to a third embodiment of the present invention;  
       FIGS. 18A, 18B , and  18 C are exemplary plan views showing respective steps of manufacturing a magnetic head according to the third embodiment;  
       FIG. 19  is an exemplary perspective view showing a magnetic head according to a fourth embodiment of the present invention; and  
       FIGS. 20A, 20B , and  20 C are exemplary plan views showing respective steps of manufacturing a magnetic head according to the fourth embodiment. 
    
    
     DETAILED DESCRIPTION  
      Various embodiments according to the invention will be described hereinafter with reference to the accompanying drawings. In general, according to an aspect of the invention, there is provided a method of manufacturing a head comprising a slider including an opposite surface which is opposite a surface of a rotatable recording medium and which has a plurality of protrusions and a negative pressure cavity, the slider being configured to maintain a fixed gap between the opposite surface and the recording medium surface by air currents generated between the recording medium surface and the opposite surface by rotation of the recording medium, and a head portion provided on the slider to read and record information from and to the recording medium, the method comprising:  
      providing a mask having a predetermined shape on the opposite surface of the slider and then subjecting the opposite surface to removing processing to form a protrusion including a protruding portion having two opposite sides; and providing another mask on the opposite surface of the slider, the another mask covering one of the two opposite sides and a part of the protruding portion, and then subjecting the opposite surface to removing processing to form a protruding portion in which the two opposite sides are adjacent to respective grooves of different depths and which is narrower than the narrowest part of the masks used.  
      According to another aspect of the invention, there is provided a head manufactured by the manufacturing method, the head comprising:  
      a slider having the opposite surface; a leading step and a pair of side steps formed on the opposite surface of the slider, each constituting the protrusion; and a negative pressure cavity defined by the leading step and pair of side steps, an end portion of each of the side steps which is positioned downstream with respect to the air currents constituting the protruding portion.  
      According to still another aspect of the invention, there is provided a disk driving device comprising: a disk-shaped recording medium; a driving section which supports and rotates the recording medium; the head according to claim  2  comprising a slider including an opposite surface which is opposite a surface of the recording medium and which maintains a fixed gap between the opposite surface and the recording medium surface via air currents generated between the recording medium surface and the opposite surface by rotation of the recording medium, and a head portion provided in the slider to record and reproduce information on and from the recording medium; and a head suspension which supports the head so that the head is movable with respect to the recording medium and which imposes a head load acting toward the surface of the recording medium, on the head.  
      With reference to the drawings, a detailed description will be given of a method of manufacturing a magnetic head, and HDD serving as disk driving devices and comprising the magnetic head manufactured by the manufacturing method, according to an embodiment of the present invention.  
      First, HDD will be described.  FIG. 1  is a plan view of HDD from which a top cover has been removed to show its internal structure.  FIG. 2  shows a floating magnetic head. As shown in  FIG. 1 , HDD has a case  12  shaped like a rectangular box and having an opened top, and the top cover (not shown) threadably fitted on the case with a plurality of screws to close the upper end opening in the case.  
      The case  12  contains a magnetic disk  16  serving as a recording medium, a spindle motor  18  serving as a driving section that supports and rotates the magnetic disk, a plurality of magnetic heads that write and read information to and from the magnetic disk, a carriage assembly  22  that supports these magnetic heads so that the magnetic heads are movable with respect to the magnetic disk  16 , and a voice coil motor (hereinafter referred to as VCM)  24  that rotates and positions the carriage assembly. The case  12  also contains a ramp load mechanism  25  that holds each magnetic head at a retreated position located away from the magnetic disk after the magnetic head has moved to an outer periphery of the magnetic disk  16 , and a circuit board unit  21  having a head IC and the like.  
      A printed circuit board is screwed to an outer surface of a bottom wall of the case  12  via the circuit board unit  21  to control the operation of the spindle motor  18 , VCM  24 , and magnetic head.  
      The magnetic disk  16  has a magnetic recording layer on a top surface and on a bottom surface. The magnetic disk  16  is fitted around an outer periphery of hub (not shown) of the spindle motor  18  and fixed on the hub by a cramp spring  17 . Driving the spindle motor  18  rotates the magnetic head  16  at a predetermined rotation speed, for example, 4,200 rpm in the direction of arrow B.  
      The carriage assembly  22  comprises a bearing portion  26  fixed on the bottom wall of the case  12 , and a plurality of arms  32  extending from the bearing portion. These arms  32  are positioned parallel to the surface of the magnetic disk  16  at predetermined intervals and extend from the bearing portion  26  in the same direction. The carriage assembly  22  includes elastically deformable suspensions  38  shaped like an elongate plate. Each suspension  38  is formed of, for example, a leaf spring. The suspension  38  has a base end fixed to a leading end of the arm  32  by spot welding, adhesion, or caulking, and extends from the arm. Each suspension  38  may be integrated with the corresponding arm  32 . The arm  32  and suspension  38  constitute a head suspension. The head suspension and the magnetic head constitute a head suspension assembly.  
      As shown in  FIG. 2 , each magnetic head  40  has a slider  42  formed in a substantially rectangular parallelepiped and a recording and reproducing head portion  44  provided in the slider. The magnetic head  40  is fixed to a gimbal spring  41  provided at a leading end of the suspension  38 . The elasticity of the suspension  38  imposes a head load L acting toward a surface of the magnetic disk  16 , on each magnetic head  40 .  
      As shown in  FIG. 1 , the carriage assembly  22  includes a support frame  45  extending from the bearing portion  26  in a direction opposite to that of the arm  32 . The support frame  45  supports a voice coil  47  partly constituting VCM  24 . The support frame  45  is formed of a synthetic resin around an outer periphery of the voice coil  47  integrally with the voice coil  47 . The voice coil  47  is positioned between a pair of yokes  49  fixed to the case  12 . The voice coil  47  constitutes VCM  24  together with the yokes  49  and a magnet (not shown) fixed to one of the yokes. The carriage assembly  22  is rotated by energizing the voice coil  47 , and the magnetic heads  40  move to desired tracks of the magnetic disk  16  and are positioned on the tracks.  
      The ramp load mechanism  25  comprises a ramp  51  provided on the bottom wall of the case  12  and placed outside the magnetic disk  16 , and a tab  53  extending from the leading end of each suspension  38 . When the carriage assembly  22  rotates to the retreated position outside the magnetic disk  16 , each tab  53  engages with a ramp surface formed on the ramp  51 . The tab  53  is then raised by the inclination of the ramp surface to unload the magnetic head  40 .  
      Now, the configuration of the magnetic head  40  will be described in detail.  FIG. 3  is a perspective view showing the magnetic head.  FIG. 4A  is a plan view of the slider. In  FIG. 4A , various hatchings indicate different depths in order to clarify areas of these depths in the disk opposite surface of the slider. For example, as shown in  FIG. 4B , a hatching ( 1 ) indicates a non-machined surface and hatchings ( 2 ), ( 3 ), ( 4 ), and ( 5 ) indicate areas of depth 120 nm, 320 nm, 1.32 μm, and 1520 μm, respectively, from the non-machined surface.  
      As shown in FIGS.  2  to  4 A, the magnetic head  40  has a slider  42  formed in a shape of a substantially rectangular parallelepiped. The slider  42  has a rectangular disk opposite surface (ABS) lying opposite the surface of the magnetic disk  16 . A longitudinal direction of the disk opposite surface  43  is defined as a first direction X. A width direction perpendicular to the first direction is defined as a second direction Y.  
      The magnetic head  40  is configured to be a floating type head. The slider  42  flies owing to air currents C generated between the disk surface and the disk opposite surface  43  by rotation of the magnetic disk  16 . While HDD is in operation, the disk opposite surface  43  of the slider  42  always lies opposite the disk surface with a gap maintained between the surfaces. The direction of the air currents C coincides with the direction B of rotation of the magnetic disk  16 . The slider  42  is placed with respect to the surface of the magnetic disk  16  so that the first direction X of the disk opposite surface  43  substantially coincides with the direction of the air currents C.  
      A substantially rectangular leading step portion  50  is protrusively provided on the disk opposite surface  43  opposite the magnetic disk surface. The leading step portion  50  is formed over an upstream area of the disk opposite surface  43  with respect to the direction of the air currents C. A pair of elongate side step portions  46  is protrusively formed on the disk opposite surface  43  and extend from the leading step portion  50  to a downstream end of the slider  42 . The side step portions  46  extend along the respective long sides of the disk opposite surface  43  and lie opposite each other at a certain interval. The leading step portion  50  and the pair of side step portions  46  constitute a generally U-shaped protrusion which is closed on the upstream side and is open toward the downstream side.  
      To maintain the pitch angle of the magnetic head  40 , a leading pad  52  is protrusively provided on the leading step portion  50  to support the slider  42  via an air film. The leading pad  52  extends continuously over the width direction of the leading pad  52  in the second direction Y. The leading pad  52  is provided at a position slightly shifted on the downstream side from the upstream side end, i.e., a flow-in side end of the slider  42  with respect to the air currents C. A side pad  48  is protrusively provided on a central part of each side step  46  in the longitudinal direction. The leading pad  52  and side pads  48  are formed substantially flat and opposite the magnetic disk surface.  
      A negative pressure cavity  54  is formed in a substantially central part of the disk opposite surface  43 . The negative pressure cavity  54  is formed of a recess defined by the pair of side step portions  46  and the leading step portion  50 . The negative pressure cavity  54  is formed on the downstream side of the leading step portion  50  with respect to the direction of the air currents C and open toward the downstream side. The negative pressure cavity  54  allows a negative pressure to be generated in the central part of the disk opposite surface  43  at all skew angle realized in HDD.  
      An end of each side step  46  located downstream with respect to the air currents C forms a protruding portion  46 A more elongate than the other portions of the side step. As shown in FIGS.  3  to  5 , each protruding portion  46 A has two sides extending in the longitudinal direction X and opposite each other. As described below, these two sides are formed by subjecting the disk opposite surface  43  to removing processing and are adjacent to grooves of different depths. For example, one of sides of the protruding portion  46 A is adjacent to the negative pressure cavity  54 . The other side is adjacent to the groove shallower than the negative pressure cavity. The width W of each protruding portion  46 A is formed in, for example, 30 μm or less, which is smaller than the minimum width of a mask used for a removing processing.  
      The slider  42  has a substantially rectangular trailing step portion  60  protrusively provided at the downstream end of the disk opposite surface  43  with respect to the direction of the air currents C. The trailing step portion  60 , constituting a protrusion, is positioned downstream of the negative pressure cavity  54  and substantially in the center of the disk opposite surface  43  across the width. A trailing pad  66  is protrusively provided over the trailing step portion  60  and opposite the magnetic disk surface.  
      A head portion  44  of the magnetic head  40  has a recording element and a reproducing element which record and reproduce information on and from the magnetic disk  16 . The reproducing element and recording element are buried in the downstream end of the slider  42  with respect to the direction of the air currents C. The reproducing element and recording element have a read/write gap  64  formed in the trailing pad  66 .  
      As shown in  FIG. 2 , the magnetic head  40  configured as described above flies in an inclined state such that the read/write gap  64  in the head portion  44  is closest to the magnetic disk surface.  
      Now, description will be given of a method of manufacturing the magnetic head in HDD configured as described above. Here, description will be given of a method of forming the disk opposite surface  43  of the slider  42  into a desired recessed and protruding shape.  
      First, a basic method will be described in which an elongate protruding portion  82  having width of 30 μm or less is formed on one surface  80   a  of a rectangular parallelepiped  80 . As shown in  FIGS. 7 and 9 A, photo resist is coated on the surface  80   a  of the rectangular parallelepiped  80  and exposed and developed to form a first mask  84   a  of a predetermined shape, for example, a rectangle. The diagonally shaded areas in  FIGS. 7 and 8  represent the first mask  84   a  and a second mask  84   b . The width of the first mask  84   a  is formed to be sufficiently larger than 30 μm. Under these conditions, as shown in  FIGS. 7 and 9 B, an area B of the surface  80   a  which is not protected by the first mask  84   a  is removed by ion milling or reactive ion etching (RIE) to form a groove of a predetermined depth. The first mask  84   a  is subsequently removed. Thus, as shown in  FIG. 9C , a rectangular protrusion corresponding to the first mask  84   a , that is, the protrusion  87  having two opposite sides  83   a  and  83   a , is formed on the surface  80   a.    
      Subsequently, as shown in  FIGS. 8 and 9 D, a second mask  84   b  is formed on the surface  80   a  of the rectangular parallelepiped  80 . The width of the second mask  84   b  is sufficiently larger than 30 μm. The second mask  84   b  covers a predetermined-width area of a protrusion  87  which includes one side  83   a  of the protrusion  87  and a predetermined area of the surface  80   a . The area of the protrusion  87  which is covered with the second mask  84   b  has a width of 30 μm or less and corresponds to the protruding portion  82 .  
      Under these conditions, as shown in  FIGS. 8 and 9 D, an area C of the surface  80   a  and protrusion  87  which is not covered with the second mask  84   b  is removed by ion milling or RIE to form a groove of a predetermined depth as shown in  FIG. 9E . The second mask  84   a  is subsequently removed. Thus, as shown in  FIGS. 9F and 6 , the deepest groove is formed in the area C of the surface  80   a  which has been subjected to the second removing processing. The protrusion  87  is partly removed to form a thin protruding portion  82  of width smaller than 30 μm which corresponds to the second mask  84 . The protruding portion  82  has two opposite sides  83   a  and  83   c  adjacent to grooves of different depths. The side  83   a  is adjacent to the groove formed by the first removing processing, and the other side  83   c  is adjacent to the shallower groove formed by the second removing processing.  
      The above method enables a protruding portion  82  having a width of 30 μm or less to be formed using a mask with a width of 30 μm or more in the smallest part.  
      Now, description will be given of a method of forming the disk opposite surface  43  of the slider  42  into the desired recessed and protruding shape using the above basic method.  
      First, as shown in  FIG. 10 , a first mask  84   a  is formed on the disk opposite surface  43  of the slider  42 , and the first mask  84   a  has a shape corresponding to the leading pad  52 , side pads  48 , and trailing pad  66 . The width of smallest part of the first mask  84   a  is sufficiently larger than 30 μm. Under these conditions, an area B of the disk opposite surface  43  which is not protected by the first mask  84   a  is removed by ion milling or RIE to form a groove of a predetermined depth, for example, 120 nm. The first mask  84   a  is subsequently removed. This forms a leading pad  52 , side pads  48 , and a trailing pad  66  on the disk opposite surface  43 . The surfaces of the leading pad  52 , side pads  48 , and trailing pad  66  are non-machined surfaces that are not subjected to removing processing.  
      Subsequently, as shown in  FIG. 11 , a second mask  84   b  is formed on the disk opposite surface  43  of the slider  42 , the second mask  84   b  has a shape corresponding to the leading step  50 , pair of side steps  46 , and trailing step  60 . The width of smallest part of the second mask  84   b  is formed to be sufficiently larger than 30 μm. Under these conditions, the area C of the disk opposite surface  43  which is not protected by the second mask  84   b  is removed by ion milling or RIE. The area C overlaps the area B subjected to the first removing processing. Correspondingly, a groove of a predetermined depth, for example, 200 nm is formed. The second mask  84   b  is subsequently removed. This forms a leading step  50 , a pair of side steps  46 , a trailing step  60 , and a negative pressure cavity  54 .  
      Then, third removing processing is executed to form elongate protruding portions  46 A at the downstream ends of the side steps  46 . In this case, as shown in  FIG. 12 , a third mask  84   c  is formed on the disk opposite surface  43  of the slider  42 , the third mask  84   c  covers the leading step  50 , pair of side steps  46 , trailing step  60 , and negative pressure cavity  54 . The third mask  84   c  is formed to cover an area of downstream end of each side step  46  which corresponds to one side of the downstream end facing the negative pressure cavity  54  and to substantially half of the downstream end in the width direction, that is, the area having a width of 30 μm or less. The width of smallest part of the third mask  84   c  is formed to be sufficiently larger than 30 μm.  
      Under these conditions, an area D of the disk opposite surface  43  and downstream end of each side step  46  which is not protected by the third mask  84   c  is removed by ion milling or RIE to form a groove of a predetermined depth. The third mask  84   c  is subsequently removed. Thus, as shown in  FIGS. 3 and 4 , the deepest groove, for example, a groove of depth 1200 nm, is formed in areas D of opposite side edges of the disk opposite surface  34  subjected to the three removing processes. The downstream end of each side step  46  is partly removed to form a thin protruding portion  46   a  of width smaller than 30 μm which corresponds to the third mask  84   c . Each protruding portion  46   a  has two opposite sides adjacent to the respective grooves of different depths. One of the sides is adjacent to the negative pressure cavity  54 , and the other side is adjacent to the shallower groove formed by the three removing processes.  
      The method of manufacturing the head configured as described above enables a protruding portion having a width of 30 μm or less to be formed using a mask with a minimum width of 30 μm or more. This increases the degree of freedom of design of the recess and protrusion shape of the disk opposite surface regardless of minimum width of the protruding portion. A high-performance magnetic head can thus be produced. Further, the width of the side step can be set at a small value of 30 μm or less, allowing the area of the negative pressure cavity to be increased. This enables a slider with an increased negative pressure to be implemented. That is, the slider has improved characteristics.  
      The above manufacturing method also enables fine protruding patterns to be formed on a disk opposite surface that is small in area. This is effective in manufacturing small-sized sliders such as femto sliders. Constructing HDD using a thus configured magnetic head enables the implementation of HDD with improved stability and reliability.  
      As shown in  FIGS. 13A, 13B ,  13 C,  13 D, and  13 E, the present inventor prepared five types of sliders  42  formed so that the protruding portion  46   a  of the side step  46  had a width W of 40 μm, 30 μm, 20 μm, 10 μm, or 0 μm. The present inventor thus analyzed the relationship between the width of the protruding portion and generation of a negative pressure.  FIGS. 13C, 13D , and  13 E show sliders manufactured by the manufacturing method according to the above embodiment. The analysis is shown in Table 1 and  FIG. 14 .  
                       TABLE 1                                      Width [μm] of protruding portion           on side pad downstream side                             Comparative example   Present embodiment                                         40   30   20   10   0                                                 Negative pressure   −1.28   −1.30   −1.33   −1.34   −1.34       generated [gf]                  
 
      Analysis conditions were as follows.  
      Disk rotation speed: 4,200 rpm  
      Disk radius: 25 mm  
      Skew angle: 0 deg  
      Head load: 2 gf  
      Pitch moment: 0.57 gfmm  
      The table and  FIG. 14  show that as the width of the protruding portion  46   a  decreases to 20 μm and then to 10 μm, a negative pressure generated increases compared to that generated when the width is 30 μm or more. That is, a higher negative pressure is generated by the slider having a narrower protruding portion which can be produced according to the present embodiment.  
      On the other hand, the above mentioned manufacturing method executes two removing processes to form a protruding portion and thus requires two mask alignments. Mask alignment tolerance is about 5 μm. Two removing processes may result in a maximum misalignment of 10 μm. Thus, the minimum width of the protruding portion formed is determined by the alignment precision of the mask. The minimum width is double a single alignment tolerance. The minimum width is estimated to be 10 μm with a normal alignment technique. However, as shown in the table and  FIG. 14 , the analysis indicates that the effect of an increase in negative pressure varies insignificantly regardless of whether the width of the protruding portion is 10 μm or 0 μm.  
      Now, description will be given of a magnetic head of HDD according to a second embodiment of the present invention.  
      As shown in  FIG. 15 , according to the second embodiment, the leading step  50 , pair of side steps  46 , and trailing step  60  are formed on the disk opposite surface  43  of the slider  42 ; the leading step  50 , pair of side steps  46 , and trailing step  60  each constitute a protrusion. The leading pad  52 , side pad  48 , and trailing pad  66  are formed on the leading step  50 , side step  46 , and trailing step  60 , respectively.  
      In each side step  46 , the protruding portion  46   a  more elongate than the other portions of the side step is formed between the leading pad  52  and the side pad  48 . Each protruding portion  46   a  has two sides extending along the longitudinal direction X and opposite each other. These two sides are formed by subjecting the disk opposite surface  43  to removing processing and are adjacent to grooves of different depths. The width W of each protruding portion  46   a  is formed to be 30 μm or less, for example, which is smaller than the minimum width of a mask used for a removing process.  
      In the second embodiment, the other arrangements of the magnetic head are the same as those in the first embodiment. The same parts are denoted by the same reference numerals and their detailed description is omitted.  
      Now, description will be given of a method of manufacturing a magnetic head configured as described above, here, a method of forming the disk opposite surface  43  of the slider  42  into a desired recess and protrusion shape.  
      As is the case with the first embodiment, as shown in  FIG. 16A , the first mask  84   a  is formed on the disk opposite surface  43  of the slider  42 ; the first mask  84   a  has a shape corresponding to the leading pad  52 , side pad  48 , and trailing pad  66 . The area B of the disk opposite surface  43  which is not protected by the first mask  84   a  is removed by ion milling or RIE to form a groove of a predetermined depth, for example, 120 nm. The first mask  84   a  is subsequently removed. This forms a leading pad  52 , side pads  48 , and a trailing pad  66  on the disk opposite surface  43 .  
      Subsequently, as shown in  FIG. 16B , the second mask  84   b  is formed on the disk opposite surface  43  of the slider  42 ; the second mask  84   b  has a shape corresponding to the leading step  50 , pair of side steps  46 , and trailing step  60 . The width of smallest part of the second mask  84   b  is formed to be sufficiently larger than 30 μm. Under these conditions, the area C of the disk opposite surface  43  which is not protected by the second mask  84   b  is removed by ion milling or RIE. The second mask  84   b  is subsequently removed. This forms a leading step  50 , a pair of side steps  46 , a trailing step  60 , and a negative pressure cavity  54 .  
      Then, third removing processing is executed to form elongate protruding portions  46 A in intermediate portions of the side steps  46 . In this case, as shown in  FIG. 16C , the third mask  84   c  is formed to cover the entire disk opposite surface  43  of the slider  42 . A pair of rectangular openings  85  is formed in the third mask  84   c . Each opening  85  is located opposite one side of the intermediate portion of the side step  46  facing the negative pressure cavity  54  and also opposite a part of the intermediate portion in the width direction. Thus, the third mask  84   c  covers a part of the intermediate portion which corresponds to one side of it lying opposite the negative pressure cavity  54  and to an area of width at most 30 μm.  
      Under these conditions, an area of the disk opposite surface  43  which is not protected by the third mask  84   c , that is, the area opposite the opening  85  in the third mask  84   c , is removed by ion milling or RIE to form a groove of a predetermined depth. The third mask  84   c  is subsequently removed. Thus, as shown in  FIG. 15 , the intermediate portion of the side step  46  is partly removed to form a thin protruding portion  46   a  having a width of 30 μm or less. The protruding portion  46   a  has two opposite sides adjacent to respective grooves of different depths.  
      The method of manufacturing the head configured as described above and this magnetic head make it possible to exert effects similar to those of the above first embodiment.  
      Now, description will be given of a magnetic head in HDD according to a third embodiment of the present invention.  
      As shown in  FIG. 17 , according to the third embodiment, a leading step  50 , pair of side steps  46 , and trailing step  60  are formed on the disk opposite surface  43  of the slider  42 ; the leading step  50 , pair of side steps  46 , and trailing step  60  each constitute a protrusion. The leading pad  52 , side pad  48 , and trailing pad  66  are formed on the leading step  50 , side step  46 , and trailing step  60 , respectively.  
      The trailing step  60  is provided with a rectangular recessed portion  60   b  that is open toward the negative pressure cavity  54  and a pair of elongate protruding portions  60   a  positioned on the opposite sides of the recessed portion  60   b  along the second direction Y. Each protruding portion  60   a  has two sides extending in the first direction X and opposite each other. These two sides are formed by subjecting the disk opposite surface  43  to removing processing and are adjacent to respective grooves of different depths. The width of each protruding portion  60   a  is formed to be 30 μm or less, for example, which is smaller than the minimum width of a mask used for a removing process.  
      In the third embodiment, the other arrangements of the magnetic head are the same as those in the first embodiment. The same parts are denoted by the same reference numerals and their detailed description is omitted.  
      Now, description will be given of a method of manufacturing a magnetic head configured as described above, here, a method of forming the disk opposite surface  43  of the slider  42  into a desired recessed and protruding shape.  
      As is the case with the first embodiment, as shown in  FIG. 18A , the first mask  84   a  is formed on the disk opposite surface  43  of the slider  42 ; the first mask  84   a  has a shape corresponding to the leading pad  52 , side pad  48 , and trailing pad  66 . The area B of the disk opposite surface  43  which is not protected by the first mask  84   a  is removed by ion milling or RIE. The first mask  84   a  is subsequently removed. This forms a leading pad  52 , side pads  48 , and a trailing pad  66  on the disk opposite surface  43 .  
      Subsequently, as shown in  FIG. 18B , the second mask  84   b  is formed on the disk opposite surface  43  of the slider  42 ; the second mask  84   b  has a shape corresponding to the leading step  50 , pair of side steps  46 , and trailing step  60 . The width of smallest part of the second mask  84   b  is formed to be sufficiently larger than 30 μm. Under these conditions, the area C of the disk opposite surface  43  which is not protected by the second mask  84   b  is removed by ion milling or RIE. The second mask  84   b  is subsequently removed. This forms a leading step  50 , a pair of side steps  46 , a trailing step  60 , and a negative pressure cavity  54 .  
      Then, third removing processing is executed to form a recessed portion  60   b  and an elongate protruding portion  60   a  in the trailing step  60 . In this case, as shown in  FIG. 18C , the third mask  84   c  is formed which covers the entire disk opposite surface  43  of the slider  42 . A rectangular opening  85  is formed in the third mask  84   c . The opening  85  is located opposite one side of the trailing step  60  facing the negative pressure cavity  54  and also opposite a part of the trailing step  60  in the width direction. Thus, the third mask  84   c  covers a part of the trailing step  60  which corresponds to two sides of it extending in the first direction X and to its area of width of 30 μm or less.  
      Under these conditions, an area of the disk opposite surface  43  which is not protected by the third mask  84   c , that is, the area opposite the opening  85  in the third mask  84   c , is removed by ion milling or RIE to form a groove of a predetermined depth. The third mask  84   c  is subsequently removed. Thus, as shown in  FIG. 17 , the trailing step  60  is partly removed to form a pair of elongate protruding portions  60   a  having a width of 30 μm or less. Each of the protruding portions  60   a  has two opposite sides adjacent to respective grooves of different depths.  
      The method of manufacturing the head configured as described above and this magnetic head make it possible to exert effects similar to those of the above first embodiment. Further, the third embodiment forms a recessed portion  60   b  and a pair of protruding portions  60   a  on the flow-in side of the trailing step  60 ; the protruding portions collect air currents in the trailing pad portion. This makes it possible to increase a positive pressure generated by the trailing step. It is also possible to increase the area of the negative pressure cavity  54 , which generates a negative pressure. Therefore, a magnetic head with excellent characteristics can be provided.  
      Now, description will be given of a magnetic head in HDD according to a fourth embodiment of the present invention.  
      As shown in  FIG. 19 , according to the fourth embodiment, a leading step  50 , pair of side steps  46 , and trailing step  60  are formed on the disk opposite surface  43  of the slider  42 ; the leading step  50 , pair of side steps  46 , and trailing step  60  each constitute a protrusion. The leading pad  52 , side pad  48 , and trailing pad  66  are formed on the leading step  50 , side step  46 , and trailing step  60 , respectively.  
      The trailing step  60  is provided with a plurality of, for example, three rectangular recessed portion  60   b  that are open toward the negative pressure cavity  54  and a plurality of, for example, four elongate protruding portions  66   a  extending from the trailing pad  66  to the negative pressure cavity  54 . Each protruding portion  66   a  has two sides extending in the first direction X and opposite each other. These two sides are formed by subjecting the disk opposite surface  43  to removing processing and are adjacent to respective grooves of different depths. The width of each protruding portion  66   a  is formed to be 30 μm or less, for example, which is smaller than the minimum width of a mask used for a removing process.  
      In the fourth embodiment, the other arrangements of the magnetic head are the same as those in the first embodiment. The same parts are denoted by the same reference numerals and their  
      Now, description will be given of a method of manufacturing a magnetic head configured as described above, here, a method of forming the disk opposite surface  43  of the slider  42  into a desired recessed and protruding shape.  
      As is the case with the first embodiment, as shown in  FIG. 20A , the first mask  84   a  is formed on the disk opposite surface  43  of the slider  42 ; the first mask  84   a  has a shape corresponding to the leading pad  52 , side pad  48 , and trailing pad  66 . The area B of the disk opposite surface  43  which is not protected by the first mask  84   a  is removed by ion milling or RIE. The first mask  84   a  is subsequently removed. This forms a leading pad  52 , side pads  48 , and a trailing pad  66  on the disk opposite surface  43 .  
      Subsequently, as shown in  FIG. 20B , the second mask  84   b  is formed on the disk opposite surface  43  of the slider  42 ; the second mask  84   b  has a shape corresponding to the leading step  50 , pair of side steps  46 , and trailing step  60 . The width of smallest part of the second mask  84   b  is formed to be sufficiently larger than 30 μm. Under these conditions, the area C of the disk opposite surface  43  which is not protected by the second mask  84   b  is removed by ion milling or RIE. The second mask  84   b  is subsequently removed. This forms a leading step  50 , a pair of side steps  46 , a trailing step  60 , and a negative pressure cavity  54 .  
      Then, third removing processing is executed to form three recessed portions  60   b  and an elongate protruding portion  60   a  in the trailing step  60 . In this case, as shown in  FIG. 20C , the third mask  84   c  is formed which covers the entire disk opposite surface  43  of the slider  42 . Three rectangular openings  85  are formed in the third mask  84   c  in parallel in the second direction Y. Each opening  85  is located opposite one side of the trailing step  60  facing the negative pressure cavity  54  and also opposite a part of the trailing step  60  in the width direction. The opening  85  is also located opposite one side of the trailing pad  66  facing the negative pressure cavity  54  and also opposite a part of the trailing step  66  in the width direction. Thus, the third mask  84   c  covers a part of the trailing step  60  and a part of the trailing pad  66 .  
      Under these conditions, an area of the disk opposite surface  43  which is not protected by the third mask  84   c , that is, the area opposite the opening  85  in the third mask  84   c , is removed by ion milling or RIE to form a groove of a predetermined depth. The third mask  84   c  is subsequently removed. Thus, as shown in  FIG. 19 , the trailing step  60  is partly removed to form three recessed portions  60   b . At the same time, the trailing pad  66  is partly removed to form four elongate protruding portions  66   a  having a width of 30 μm or less. Each of the protruding portions  66   a  has two opposite sides adjacent to respective grooves of different depths.  
      The method of manufacturing the head configured as described above and this magnetic head make it possible to exert effects similar to those of the above first embodiment. Further, the fourth embodiment forms a plurality of recessed portion  60   b  and a plurality of protruding portions  66   a  on the flow-in side of the trailing step  60 ; the protruding portions collect air currents in the trailing pad portion. This makes it possible to increase a positive pressure generated by the trailing step. It is also possible to increase the area of the negative pressure cavity  54 , which generates a negative pressure. Therefore, a magnetic head with excellent characteristics can be provided.  
      While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.  
      For example, the shapes of the protruding and recessed portions formed on the disk opposite surface of the slider are not limited to rectangles. The protruding and recessed portions may have various shapes. The present invention is applicable not only to pico sliders, pemto sliders, and femto sliders but also to larger sliders. Moreover, the present invention is applicable not only to the above floating type slider but also to a contact type head having a recording element that contacts the surface of a recording medium.