Abstract:
An air bearing slider for supporting a transducer over a moving recording medium and a method for fabricating such an air bearing slider. The air bearing slider lifts off the recording medium with a predetermined take-off velocity when the recording medium begins to move. The air bearing slider has a first etched region that has a first etch depth and a second etched region that has a second etch depth. The etch depth ratio of the first etch depth to the second etch depth provides a pad-type air bearing slider with a take-off velocity ratio that is greater than or equal to 100%. The etch depth ratio of the first etch depth to the second etch depth provides a rail-type air bearing slider with a take-off velocity ratio that is greater than or equal to approximately 70%.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to air bearing sliders that support transducers over moving recording media and, more particularly, to an air bearing slider which exhibits an improved takeoff velocity. 
     2. Background Description 
     Conventional magnetic disk drives are information storage devices which utilize at least one rotatable magnetic media disk with concentric data tracks, a read/write transducer for reading and writing data on the various tracks, an air bearing slider for holding the transducer adjacent to the track generally in a flying mode above the media, a suspension for resiliently holding the slider and the transducer over the data tracks, and a positioning actuator connected to the suspension for moving the transducer across the media to the desired data track and maintaining the transducer over the data track during a read or a write operation. 
     During operation of the magnetic disk drive, the slider is suspended (i.e., “flies”) above the magnetic media disk on a cushion of air. The separation between the slider and the magnetic media disk is referred to as the “fly height.” The goal of air bearing slider design is to achieve a minimal fly height without having the slider physically impact the magnetic media disk. Smaller fly heights are desired so that the transducer can distinguish between the magnetic fields emanating from more closely spaced tracks of the magnetic disk media, thereby making possible an increased recording density for the magnetic disk drive. 
     In so-called “contact start-stop”(“CSS”) magnetic disk drive designs, it is common for a region on the surface of the inner diameter of the magnetic media to be referred to as the “landing zone.” This is the region from which the slider lifts off when the magnetic media disk begins moving and is the region to which the slider returns when the magnetic media disk ceases moving. 
     When used with disks that include a landing zone, a slider must achieve lift quickly once the disk has begun moving to clear the disk surface. The longer the slider takes to lift off the surface (i.e., the slower the slider&#39;s take-off velocity), the longer the time (or the number of rotations) that the slider is in contact with the magnetic media disk. The result is increased wear at the interface of the slider and the magnetic media disk. Furthermore, a slider that has a slow take-off velocity also has the added drawback that any collisions between it and the magnetic media disk that occur at the late stages of the take-off process occur at a high velocity. Such high velocity collisions also increase the wear at the interface of the slider and the magnetic media disk. 
     The prior art has addressed the problem of achieving a desired take-off, or clearance between the slider and the magnetic media disk. For example, U.S. Pat. No. 5,418,667 to Best et al. entitled SLIDER WITH TRANSVERSE RIDGE SECTIONS SUPPORTING AIR-BEARING PADS AND DISK DRIVE INCORPORATING THE SLIDER (“the Best &#39;667 Patent”) discloses an air bearing slider pad which rests on a step surface and which is angled to provide extra air bearing lift to the slider at the inner diameter of the magnetic media disk. U.S. Pat. No. 5,870,250 to Bolasna et al. entitled METHOD AND APPARATUS FOR IMPROVING FILE CAPACITY USING DIFFERENT FLYING HEIGHT PROFILES discloses different embodiments of air bearing sliders which use angled rails to create desired air pressure distributions at predetermined radii of a recording medium. Similarly, U.S. Pat. No. 5,796,550 to O&#39;Sullivan et al. entitled METHOD AND APPARATUS FOR PROVIDING DIVERGING RAIL EDGE GEOMETRY FOR AIR BEARING SLIDER discloses a slider having air bearing pads or rails that have at least one edge diverging from the side edges of the pads or rails support structure to reduce the slider&#39;s sensitivity to skew and roll. 
     The prior art has also addressed the problem of the altitude sensitivity of the fly height air bearing sliders. U.S. Pat. No. 5,777,825 to Dorius entitled NEGATIVE PRESSURE STEP PAD AIR BEARING DESIGN AND METHOD FOR MAKING THE SAME (“the Dorius &#39;825 Patent”) discloses several embodiments of an air bearing slider which use front and back air bearing surface pads that rest on leading and trailing step surfaces. According to the Dorius &#39;825 Patent, prior art air bearing slider designs exhibit sensitivity to changes in altitude. This sensitivity poses a reliability problem for magnetic disk drives in that a decrease in a slider&#39;s fly height caused by an increase in altitude results in more interactions between the slider and the magnetic media disk of the magnetic disk drive. Consequently, the incidence of magnetic disk drive failures increases with increases in altitude. The Dorius &#39;825 Patent is directed to providing an air bearing slider which possesses a reduced sensitivity to changes in altitude. The air bearing slider design described in the Dorius &#39;825 Patent takes a step-pad (i.e., bobsled) design and adds a negative pressure (i.e., subambient pressure) pocket between the leading-edge and trailing edge pads of the slider. The slider is described as requiring only two etch depths to manufacture, and the negative pressure pocket is described as being etched to a specific depth to achieve the desired reduction in altitude sensitivity. 
     The prior art has not, however, addressed the problem of improving the take-off velocity of an air bearing slider relative to its take-off location on the disk and its target fly height at that location, i.e., its “true” take-off velocity. The Best &#39;667 Patent, for example, is directed to achieving a clearance between the slider and the magnetic media disk, but it does not address the problem of achieving an improved (i.e., faster) take-off velocity for the slider. The Dorius &#39;825 Patent, by way of another example, is strictly directed to improving the altitude sensitivity of sliders, and also does not recognize the need to improve the take-off velocity of air bearing sliders. Nor does the Dorius &#39;825 Patent recognize the need to balance the altitude sensitivity of a slider with its take-off velocity. Accordingly, there is a need in the art for an air bearing slider that has an improved take-off velocity. 
     SUMMARY 
     The present invention is directed to an apparatus that satisfies the need for an air bearing slider that has an improved take-off velocity. According to the embodiments of the present invention, the time (or the number of rotations) during which the slider is in contact with the magnetic media disk is reduced. 
     According to an embodiment of the present invention, an air bearing slider for supporting a transducer over a moving recording medium that can lift off the recording medium with a predetermined take-off velocity when the recording medium begins to move comprises: a first etched region having a first etch depth and a second etched region having a second etch depth, wherein an etch depth ratio of the first etch depth to the second etch depth provides the air bearing slider with a take-off velocity ratio that is greater than or equal to 100%. 
     The second etch depth may provide a predetermined altitude ratio for the air bearing slider, and may generally be in the range of approximately 500 nanometers to approximately 3000 nanometers. The first etch depth may be shallow in relation to the second etch depth, and may generally be in the range of approximately 50 nanometers to approximately 300 nanometers. The etch depth ratio may be less than or equal to 10%. The second etched region may comprise a negative pressure region. 
     The air bearing slider may further comprise a pad, and the first etched region may comprise a ramp for compressing air flow incident on the pad. The ramp may comprise a step ramp. The second etched region may comprise a negative pressure region. The negative pressure region may be defined by the pad. The pad may have a generally horseshoe shape. 
     According to another embodiment of the present invention, an air bearing slider for supporting a transducer over a moving recording medium wherein the air bearing slider lifts off from the recording medium with a predetermined take-off velocity when the recording medium begins to move comprises: a first pad having a first ramp surface for compressing air flow incident on the first pad, the first pad defining a negative pressure region of the slider; a second pad having a second ramp surface for compressing air flow incident on the second pad; and a third pad having a third ramp surface for compressing air flow incident on the third pad; wherein the second and third ramp surfaces are formed at a first etch depth and the negative pressure region is formed at a second etch depth such that the etch depth ratio of the first etch depth to the second etch depth provides the air bearing slider with a take-off velocity ratio that is greater than or equal to 100%. 
     The second etch depth may provide a predetermined altitude ratio for the air bearing slider. The first etch depth may be shallow in relation to the second etch depth. The etch depth ratio may be less than or equal to 10%. 
     The first pad may be formed at a leading edge of the air bearing slider. The second pad may be formed at a trailing edge of the air bearing slider. The third pad may be formed at a trailing edge of the air bearing slider. The ramp surfaces may comprise stepped contours. The first pad may generally form a horseshoe shape. 
     According to a further embodiment of the present invention, an air bearing slider for supporting a transducer over a moving recording medium that can lift off the recording medium with a predetermined take-off velocity when the recording medium begins to move comprises: at least one rail provided with a first etched region along a side edge, the first etched region having a first etch depth; and a second etched region having a second etch depth; wherein an etch depth ratio of the first etch depth to the second etch depth provides the air bearing slider with a take-off velocity ratio that is greater than or equal to 80%. 
     The second etch depth may provide a predetermined altitude ratio for the air bearing slider. The first etch depth may be shallow in relation to the second etch depth. The etch depth ratio may be less than or equal to 10%. The first etched region may comprise a stepped contour. 
     According to yet another embodiment of the present invention, a method for fabricating an air bearing slider comprises the steps of: etching a first region of the air bearing slider to a first etch depth, etching a second region of the air bearing slider to a second etch depth, and choosing an etch depth ratio of the first etch depth to the second etch depth to provide the air bearing slider with a predetermined take-off velocity ratio. 
     The etch depth ratio may be chosen to be less than or equal to 10%. 
     The second etch depth may be chosen to provide the slider with a predetermined altitude ratio. 
     The second etching step may comprise etching the second region to form a negative pressure region. The etch depth ratio may be chosen to provide a take-off velocity ratio greater than or equal to 100%. 
     The first etching step may comprise etching the first region to form a ramp for a pad of the air bearing slider. The first etching step may further comprise etching the first region such that the ramp forms a stepped contour. The second etching step may comprise etching the second region to form a negative pressure region. The etch depth ratio may be chosen to be less than or equal to 10%. 
     According to a further embodiment of the present invention, a method for fabricating an air bearing slider comprises the steps of: forming a first pad having a first ramp surface for compressing air flow incident on the first pad, the first pad defining a negative pressure region of the slider; forming a second pad having a second ramp surface for compressing air flow incident on the second pad; and forming a third pad having a third ramp surface for compressing air flow incident on the third pad; wherein the ramp surfaces are formed by etching to a first etch depth and the negative pressure region is formed by etching to a second etch depth; and choosing an etch depth ratio of the first etch depth to the second etch depth that provides the air bearing slider with a take-off velocity ratio that is greater than or equal to 100%. 
     The etch depth ratio may be chosen to be less than or equal to 10%. The second etch depth may be chosen to provide a predetermined altitude ratio. 
     The first forming step may comprise forming the first pad at a leading edge of the air bearing slider. The first forming step may comprise the step of forming a generally horseshoe shape. The second forming step may comprise forming the second pad at a trailing edge of the air bearing slider. The third forming step may comprise forming the third pad at a trailing edge of the air bearing slider. The second and third forming steps may comprise forming ramp surfaces that have stepped contours. 
     According to an even further embodiment of the present invention, a method for fabricating an air bearing slider comprises the steps of: etching a first region of the air bearing slider to a first etch depth, etching a second region of the air bearing slider to a second etch depth deeper than first etch depth to provide a desired altitude ratio, and choosing an etch depth ratio of the first etch depth to the second etch depth to provide the air bearing slider with a predetermined combination of the altitude ratio and a take-off velocity ratio. 
     The etch depth ratio may be chosen to be less than or equal to 10%. 
     According to a further embodiment of the present invention, a method for fabricating an air bearing slider, the method comprising the steps of: etching an edge of a rail to provide a first region of the air bearing slider at a first etch depth; etching a second region of the air bearing slider to a second etch depth; and choosing an etch depth ratio of the first etch depth to the second etch depth to provide the air bearing slider with a predetermined take-off velocity ratio. 
     The etch depth ratio may be chosen to be less than or equal to 10%. 
     The first etching step may comprise etching the first region to form a stepped contour. 
     The second etch depth may be chosen to provide the slider with a predetermined altitude ratio. The second etching step may comprise etching the second region to form a negative pressure region. 
     The etch depth ratio may be chosen to provide a take-off velocity ratio greater than or equal to 80%. 
     According to another embodiment of the present invention, an air bearing slider for supporting a transducer over a moving recording medium that can lift off the recording medium with a predetermined take-off velocity when the recording medium begins to move comprises: a first etched region having a first etch depth that is greater than or equal to approximately 50 nanometers; and a second etched region having a second etch depth; wherein an etch depth ratio of the first etch depth to the second etch depth provides the air bearing slider with a take-off velocity ratio that is greater than or equal to approximately 70%. 
     The first etch depth may be less than or equal to approximately 300 nanometers. The second etch depth may be in the range of approximately 500 nanometers to approximately 3,000 nanometers. The etch depth ratio may be less than or equal to 15%. 
     According to yet another embodiment of the present invention, an air bearing slider for supporting a transducer over a moving recording medium that can lift off the recording medium with a predetermined take-off velocity when the recording medium begins to move comprises: a first etched region having a first etch depth; and a second etched region having a second etch depth that is greater than or equal to approximately 500 nanometers; wherein an etch depth ratio of the first etch depth to the second etch depth provides the air bearing slider with a take-off velocity ratio that is greater than or equal to 70%. 
     The second etch depth may be less than or equal to approximately 3000 nanometers. The first etch depth may be in the range of approximately 50 nanometers to approximately 300 nanometers. The etch depth ratio may be less than or equal to 15%. 
     According to a further embodiment according to the present invention, a method for fabricating an air bearing slider comprises the steps of: etching a first region of the air bearing slider to a first etch depth that is greater than or equal to approximately 50 nanometers; etching a second region of the air bearing slider to a second etch depth; and choosing an etch depth ratio of the first etch depth to the second etch depth to provide the air bearing slider with a take-off velocity ratio that is greater than or equal to approximately 70%. 
     The first etch depth may be less than or equal to approximately 300 nanometers. The second etch depth may be in the range of approximately 500 nanometers and approximately 3000 nanometers. The etch depth ratio may be chosen to be less than or equal to 15%. 
     According to an even further embodiment of the present invention, a method for fabricating an air bearing slider comprises the steps of: etching a first region of said air bearing slider to a first etch depth; etching a second region of aid air bearing slider to a second etch depth that is greater than or equal to approximately 500 nanometers; and choosing an etch depth ratio of said first etch depth to said second etch depth to provide said air bearing slider with a take-off velocity ratio that is greater than or equal to approximately 70%. 
     The second etch depth may be less than or equal to approximately 3000 anometers. The first etch depth may be in the range of approximately 50 anometers and approximately 300 nanometers. The etch depth ratio may be chosen to be less than or equal to 15%. 
    
    
     The above, and other features, aspects, and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 shows a bottom plan view of an embodiment of an air bearing slider according to the present invention when operationally oriented with respect to the disk surface; 
     FIG. 2 illustrates the relationship between the Take-Off Velocity Ratio and the Etch Depth Ratio for embodiments of air bearing sliders according to the present invention; 
     FIG. 3 illustrates the relationship between the Etch Depth Ratio, the Take-Off Velocity Ratio, and the Altitude Ratio for the air bearing slider shown in FIG. 1; 
     FIG. 4 shows a bottom plan view of another embodiment of an air bearing slider according to the present invention when operationally oriented with respect to the disk surface; 
     FIG. 5 shows a bottom plan view of yet another embodiment of an air bearing slider according to the present invention when operationally oriented with respect to the disk surface; 
     FIG. 6 shows a bottom plan view of a further embodiment of an air bearing slider according to the present invention when operationally oriented with respect to the disk surface; 
     FIG. 7 shows a bottom plan view of an even further embodiment of an air bearing slider according to the present invention when operationally oriented with respect to the disk surface; 
     FIGS. 8A-8D show bottom plan views of representative embodiments of outer trailing edge ramps and pads for the air bearing sliders shown in FIGS. 4-7 when operationally oriented with respect to the disk surface; 
     FIGS. 9A-9D show bottom plan views of representative embodiments of inner trailing edge ramps and pads for the air bearing sliders shown in FIGS. 4-7 when operationally oriented with respect to the disk surface; 
     FIGS. 10A-10D are useful in explaining advantages associated with air bearing slider shown in FIG. 1; 
     FIG. 11 shows a bottom plan view of an embodiment of a prior art rail type air bearing slider; and 
     FIG. 12 is an exploded view of an exemplary disk drive that can be used with the present invention. 
    
    
     DETAILED DESCRIPTION 
     An exploded view of an exemplary disk drive that can be used with the present invention is shown in FIG. 1 of U.S. Pat. No. 5,796,550 to O&#39;Sullivan et al. and is reproduced herein as FIG.  12 . Referring to FIG. 12, disk drive  10  includes a housing  12  and a housing cover  14  which, after assembly, is mounted within a frame  16 . Mounted within the housing is a spindle shaft  22 . Rotatably attached to the spindle shaft  22  are a number of disks  24 . Eight disks  24  are attached to the spindle shaft  22  in spaced apart relation. The disks  24  rotate on spindle shaft  22  which is powered by a motor (not shown). Information is written on or read from the disks  24  by heads or magnetic transducers (not shown) which are supported by sliders  26 . Preferably, the inventive sliders described further herein are coupled to the suspensions or load springs  28 . The load springs  28  are attached to separate arms  30  on an E block or comb  32 . The E block or comb  32  is attached at one end of an actuator arm assembly  36 . The actuator arm assembly  36  is rotatably attached within the housing  12  on an actuator shaft  38 . It should be appreciated by those having ordinary skill in the art that the embodiments of sliders according to the present invention are not meant to be limited to the disk drive  10  described above. 
     FIG. 1 shows an embodiment of an air bearing slider, generally designated  100 , according to the present invention. The slider  100  includes a leading edge  102 , a trailing edge  104 , an inner edge  106 , and an outer edge  108 . The air flow created by the movement of the disk (not shown) is incident upon the slider  100  at its leading edge  102 . The inner edge  106  of the slider  100  is defined by its proximity to the inside diameter of the disk when the slider  100  is suspended over the disk. Conversely, the outer edge  108  is defined by its proximity to the outer diameter of the disk when the slider  100  is suspended over the disk. The currently preferred embodiment of the slider  100  is manufactured from an alumina titanium carbide (AlTiC) material. It will be appreciated by those having skill in the art that the slider  100  may be manufactured from other suitable materials. 
     The slider  100  further includes a leading edge ramp  110 , a leading edge pad  112 , an inner trailing edge ramp  114 , an inner trailing edge pad  116 , an outer trailing edge ramp  118 , and an outer trailing edge pad  120 . Pads  112 ,  116 , and  120  each form an air bearing surface (“ABS”). In the preferred embodiment, ramps  110 ,  116  and  118  form steps with respect to their respective pads, but other shapes for the ramps  110 ,  114  and  118  are also envisioned, including linear tapers or more complicated contours. The leading edge pad  112  and the inner trailing edge ramp  114  are positioned to provide an inner air “bleed slot”  122  therebetween. 
     Likewise, the leading edge pad  112  and the outer trailing edge ramp  118  are positioned to provide an outer air “bleed slot”  124  therebetween. The slider  100  also includes an outer border region  126  around its perimeter. The magnetic transducer  148  is formed on the outer trailing edge pad  120  by techniques that are well known in the art. 
     The leading edge ramp  110  is formed by etching the slider  100  to a first depth. According to the embodiments of the present invention, the first etch depth s preferably greater than or equal to approximately 50 nanometers and less than or equal to approximately 300 nanometers. In a presently preferred embodiment, the slider  100  is etched to a shallow first depth of approximately 140 nanometers to form the leading edge ramp  110 . The slider  100  can be etched to the first depth using any suitable technique that is known to those having skill in the art, including but not limited to ion milling, ion bombardment with a chemical assist (using boron trichloride or a less reactive gas), or inductively coupled plasma etching using a reactive gas. In the presently preferred embodiments according to the present invention, the slider  100  is formed by inductively coupled plasma etching using Halocarbon-14 (CF 4). The leading edge ramp  110  is contiguous with the leading edge pad  112  along the contour  128  of the pad  112 . As is well known in the art, the leading edge ramp  110  compresses the air flow incident to the slider  100  at its leading edge  102  to provide positive pressure under the leading edge pad  112  to lift the slider  100  off of the disk. 
     According to an embodiment of the present invention, the leading edge pad  112  has a generally horseshoe (or “wrap-around”) shape and includes an inner leg  130 , an outer leg  132 , and a bridge portion  134  connecting the inner leg  130  to the outer leg  132 . Again, the legs  130  and  132  are defined as “inner” or “outer” legs based on their proximity to either the inside diameter of the disk or the outer diameter of the disk when the slider  100  is suspended over the disk, as described above with respect to the edges  106  and  108  of the slider  100 . 
     As shown in FIG. 1, the leading edge pad  112  may be asymmetrical in two senses. First, the leading edge pad  112  may be asymmetrical about its longitudinal axis because the shapes and lengths of the legs  130  and  132  need not be identical. Second, the bridge portion  134  may be asymmetrical about the longitudinal axis of the slider  100  because the bridge portion  134 , as shown in FIG. 1, is shifted toward the outer edge  108  of the slider  100 . The shape of the legs  130  and  132  and the position of the bridge portion  134  relative to the longitudinal axis of the slider  100  are chosen to optimize the performance of the slider  100  for a particular disk drive, and are thus left to the judgment of one having skill in the art. Therefore, the leading edge pad  112  may be symmetrical, or may exhibit varying degrees of asymmetry, depending upon the requirements of the particular disk drive in which the slider  100  is used. 
     The bridge portion  134  and the legs  130  and  132  define a cavity  136  which, as is well known in the art, functions as a negative pressure area (i.e., has a sub-ambient pressure). According to the embodiments of the present invention, the second etch depth is greater than the first etch depth. More specifically, the second etch depth is preferably greater than or equal to approximately 500 nanometers and less than or equal to approximately 3000 nanometers. In a presently preferred embodiment, the cavity  136  is etched to a second depth of approximately 1800 nanometers using any suitable etching technique known to those skilled in the art, including but not limited to those techniques previously identified herein. 
     In the embodiment of FIG. 1, slider  100  is provided with two trailing edge pads having respective ramps. The inner trailing edge ramp  114  is formed by etching the slider  100  to a predetermined depth using a technique known to those skilled in the art, as previously described herein. The inner trailing edge pad  116  includes ramp  118 . In the preferred embodiment, ramps  110 ,  114  and  118  are all etched to the same depth (e.g., the first depth of the leading edge ramp  110 ) during a single etching operation. 
     The prior art has recognized that the etch depths of the cavity  136  and the ramps  110 ,  114 , and  118  affect the altitude sensitivity of an air bearing slider. The Dorius &#39;825 Patent, for example, is directed to an air bearing slider which possesses a reduced altitude sensitivity. That slider includes a deep etched negative pressure pocket and several shallow etched step regions which are all etched to the same depth. The Dorius &#39;825 Patent teaches that the depth of the negative pressure pocket can be optimized to minimize the altitude sensitivity of the slider, and that the depth of the shallow step regions can then be optimized to achieve a desired fly height profile. 
     The Altitude Ratio of the slider, defined as the fly height of the slider at an altitude of 10,000 feet above sea level to the fly height of the slider at sea level, is but one aspect of the slider&#39;s performance. Those having ordinary skill in the art realize that, in designing a particular air bearing slider, the altitude sensitivity must be considered in conjunction with other aspects of the slider&#39;s performance, for example its take-off velocity. The goal in designing the slider thus becomes achieving an appropriate balance between the slider&#39;s altitude sensitivity and its take-off velocity. The Dorius &#39;825 Patent, in focusing solely on the altitude sensitivity of the slider, provides no insight into the effect of the etch depths of the slider on its take-off velocity. 
     According to an embodiment of the present invention, the inventors have made the significant discovery that the ratio of the shallow etch depth of the ramps  110 ,  114 , and  118  to the deep etch depth of the cavity  136  can be varied advantageously to affect the take-off velocity of the slider  100 . The take-off point of the slider  100  is the point at which the body of the slider  100  is no longer in contact with (i.e., flies above) the surface of the disk. FIG. 2 illustrates the take-off velocity ratio (“TOV Ratio”) of a slider as a function of its Etch Depth Ratio. The TOV Ratio is defined as the ratio of the fly height of the slider in the landing zone at one-half of the target operating rotational velocity of the disk to the fly height of the slider in the landing zone at the target operating rotational velocity of the disk. The Etch Depth Ratio is defined as the ratio of the shallow etch depth of the ramps  110 ,  114 , and  118  to the deep etch depth of the cavity  136 . 
     FIG. 2 generally shows that, to achieve an improved take-off velocity i.e., a large TOV Ratio, air bearing sliders according to the preferred embodiments of the present invention should have a small Etch Depth Ratio, i.e., a shallow first etch depth in relation to the deeper etch depth of the cavity. Specifically, the upper line  202  of FIG. 2, which represents the TOV Ratio for the slider  100 , shows that the slider  100  achieves TOV Ratios in the range of approximately 30% and above 120%. FIG. 2 further shows that the TOV Ratio is greatest for values of the Etch Depth Ratio that are less than 5.0%. In a presently preferred embodiment, the Etch Depth Ratio of the slider  100  is approximately 7.77% (140 nanometers/1800 nanometers). The large TOV Ratio indicates that sliders fabricated according to the embodiments of the present invention attain a larger fly height in the landing zone at a lower rotational velocity of the media or disk and hence exhibit an improved take-off velocity. 
     According to a further aspect of the present invention, the inventors have determined that the TOV Ratio is greatest for smaller values of the Etch Depth Ratio not only for the pad-type sliders specifically described herein, but also for other sliders that are formed with first and second etch depths, including the well known class of rail-type sliders, some of which may be fabricated using double etch techniques. FIG. 11 shows a bottom plan view of a prior art rail-type air bearing slider. The slider  1100  includes rails  1102  and  1104 . Rail  1102  has regions  1106  and  1108  that are etched to a first depth along its side edges. Similarly, rail  1104  has regions  1110  and  1112  that are etched to the first depth along its side edges. The slider  1100  further includes a subambient pressure region  1114  that is etched to a second depth that is deeper than the first depth. Although rail-type sliders of the type shown in FIG. 11 are prevalent in the prior art, there is no teaching in the prior art regarding optimizing the Etch Depth Ratios of such prior art rail-type sliders to improve their take-off velocities. In accordance with the present invention, the Etch Depth Ratio of the first etch depth of the regions  1106  and  1108  to the second etch depth of the subambient pressure region  1114  can be optimized to improve the TOV Ratio of the slider  1100 . 
     The lower line  204  of FIG. 2 represents the TOV Ratio for the rail-type slider  1100  shown in FIG.  11 . As shown in FIG. 2, the TOV Ratio is greatest for values of the Etch Depth Ratio that are less than 5.0%, and achieves a TOV Ratio in excess of 80%. The lower line  204  of FIG. 2 thus indicates that even rail-type sliders with two etch depths that have small Etch Depth Ratios attain larger fly heights at lower rotational velocities and hence exhibit improved take-off velocities, i.e., have large TOV Ratios. 
     At the same time, while a particular Etch Depth Ratio may be advantageous with respect to achieving a desired take-off velocity, that same Etch Depth Ratio may not be desirable with respect to another aspect of the slider&#39;s performance. FIG. 3 shows the relationship between Altitude Ratio, TOV Ratio, and Etch Depth Ratio for three embodiments of an air bearing slider according to the present invention. The three embodiments differ in the magnitude of the first etch depth for the ramps  110 ,  114 , and  118 . Trend line  302  corresponds to an embodiment that has a first etch depth of approximately 100 nanometers; trend line  304  corresponds to another embodiment that has a first etch depth of approximately 140 nanometers; and trend line  306  corresponds to a third embodiment that has a first etch depth of approximately 200 nanometers. For each of the three embodiments, the Altitude Ratio was determined for deep etch depths of the cavity  136  of approximately 2200 nanometers, 1800 nanometers, and 1200 nanometers. For each of the trend lines  302 ,  304 , and  306 , the lowest values of Altitude Ratio and Etch Depth Ratio are provided at a deep etch depth of 2200 nanometers, and the highest values of Altitude Ratio and Etch Depth Ratio are provided at a deep etch depth of 1200 nanometers. As will be appreciated from an examination of trend lines  302 ,  304 , and  306 , the highest values of the Altitude Ratio for each of the three embodiments are approximately equal to one another, even though the first depths that correspond to the trend lines  302 ,  304 , and  306  are different. Thus, the Altitude Ratio for each of the embodiments is determined by the magnitude of the deep etch depth of the cavity  136 . 
     The relationship between TOV Ratio and Etch Depth Ratio is represented in FIG. 3 by trend line  308 . This relationship is affected by the magnitude of the first depth of the ramps  110 ,  114 , and  118 , although there is only the one trend line  308  corresponding to the three depths of the ramps  110 ,  114 , and  118  examined in FIG.  3 . However, the effect of different first etch depths on TOV Ratio is not pronounced, so the relationship between TOV Ratio and Etch Depth Ratio in this example appears to remain effectively the same regardless of the magnitude of the first etch depth. 
     The Altitude Ratio trend lines  302 ,  304 , and  306  shown in FIG. 3 slope upwardly as Etch Depth Ratio increases, thereby indicating that an improved Altitude Ratio is achieved with larger values of the Etch Depth Ratio. Conversely, the TOV Ratio trend line  308  shown in FIG. 3 slopes downwardly as Etch Depth Ratio increases, thereby indicating that an improved TOV Ratio is achieved with smaller values of the Etch Depth Ratio. Those having skill in the art will thus appreciate that the designer of a slider must strike a desired balance between, for example, the slider&#39;s take-off velocity (as represented by its TOV Ratio) and its altitude sensitivity (as represented by its Altitude Ratio). In other words, to achieve an optimal combination for TOV Ratio and Altitude Ratio for a particular slider design, the designer of the slider must specify a relatively shallow deep etch depth for the cavity  136  and a very shallow first etch depth of the ramps  110 ,  14 , and  118 . For example, referring to FIG. 3, one having ordinary skill in the art will understand that only the first and second embodiments associated respectively with trend lines  302  and  304  can provide a TOV Ratio of 80% in conjunction with an Altitude Ratio of 80%. 
     It will be further appreciated by those having ordinary skill in the art that the Altitude Ratio trend lines  302 ,  304 , and  306  and the TOV Ratio trend line  308  shown in FIG. 3 can be used to define a “design space” within which the designer of an air bearing slider can strike the desired balance between competing performance characteristics of the slider. A designer can, for instance, choose a particular balance between the take-off velocity and the altitude sensitivity of the slider by selecting particular percentage values of the TOV Ratio and the Altitude Ratio, and then determining the range of values for the Etch Depth Ratio that will effect the desired balance. For example, referring to FIG. 3, if the designer desires to strike the balance between the take-off velocity and the altitude sensitivity of the slider by defining a design space that is characterized by a TOV Ratio equal to 60% and an Altitude Ratio that is equal to 80%, the slider will exhibit the desired balance in performance between take-off velocity and altitude sensitivity for Etch Depth Ratios in the range of approximately 6% and approximately 13% (for a shallow etch depth of 100 nanometers), of approximately 9% and approximately 13% (for a shallow etch depth of 140 nanometers), and of approximately 12% and approximately 13% (for a shallow etch depth of 200 nanometers). 
     Once a desired ratio of the etch depths of the ramps  110 ,  114 , and  118  to the etch depth of the cavity  136  has been chosen, one skilled in the art can choose the shape, dimension, and placement of the leading edge pad  112  and the trailing edge pads  116  and  120  to optimize the fly height profile and take-off velocity of the slider  100 . For example, the shapes of the portion  138  of the leading edge of the ramp  114  and the leading edge  142  of the inner trailing edge pad  116  are chosen to optimize (e.g., increase) the effective lengths of the ramp  114  and the pad  116  for air flowing across the ramp  114  and the pad  116  at the inner diameter of the disk to compensate for the lower linear velocities and negative skew angles associated with the inner diameter of the disk. As used herein, the term “effective length” is defined as the length dimension (of a ramp or a pad), in the direction of air flow, over which air flows at the skew angle of the slider. The exemplary embodiment of slider  100  shown in FIG. 1 provides an optimized effective length of the ramp  114  at the inner diameter of the disk by shaping the leading edge  142  of the inner trailing edge pad  116  such that the edge  142  is orthogonal to the direction of air flow incident on the ramp  114  and the pad  116  when the slider is oriented in the landing zone. This optimized length of the ramp  114  at the landing zone will then provide increased pressure for the pad  116 , as shown in FIG. 1, if the pad  116  is of a sufficient size. 
     As shown in FIG. 1, the portion  138  of the leading edge of the ramp  114  is angled with respect to the trailing edge  140  of the pad  116  (i.e., the portion  138  and the trailing edge  140  are not parallel) such that an air flow vector representing the air flow incident on the portion  138  of the leading edge of the step ramp  114  is generally orthogonal to the portion  138  when the slider  100  is at a maximum negative skew angle over the landing zone of the disk. Consequently, the effective length of the ramp  114  at the landing zone of the disk, defined as the length of the ramp  114  over which air flows and is thereby compressed, is maximized. Concomitantly, the leading edge  142  of the inner trailing edge pad  116  is shaped such that the compressed air from the ramp  114  flows over a maximum effective length of the pad  116 . The result is high positive pressure under the pad  116  when the slider  100  is at its maximum negative skew angle over the landing zone of the disk. 
     Similarly, the shapes of the portion  144  of the leading edge of the ramp  118  and the leading edge  145  of the outer trailing edge pad  120  are chosen to optimize (e.g., decrease) the effective lengths of the ramp  118  and the pad  120  for air flowing across the ramp  118  and the pad  120  at the outer diameter of the disk to compensate for the higher linear velocities and positive skew angles associated with the outer diameter of the disk. For example, the embodiment of slider  100  shown in FIG. 1 provides an optimized effective length of the ramp  118  at the outer diameter of the disk by shaping the leading edge  145  of the inner trailing edge pad  120  such that the edge  145  is not orthogonal to the direction of air flow incident on the ramp  118  and the pad  120  when the slider is oriented at the outer diameter of the disk. This optimized length of the ramp  118  at the outer diameter of the disk will then provide decreased pressure for the pad  120 . 
     As shown in FIG. 1, the outer trailing edge ramp  118  is formed by etching the slider  100  to a predetermined depth using a technique known to those skilled in the art, as previously described herein. The step ramp  118  converges air flow to provide positive pressure for the inner trailing edge pad  120 . The leading edge  144  of the step ramp  118  is generally parallel to the trailing edge  146  of the pad  120 . The shape of the pad  120  is designed to optimize the effective length of the pad  120  when the slider is at the outer diameter of the disk. In this way, the positive pressure under the pad  120  is tuned to achieve and maintain target fly height when the slider  100  is at the outer diameter of the disk. 
     Those having skill in the art will appreciate that, since the skew angle of the slider  100  changes as the slider  100  moves from the inner diameter of the disk to the outer diameter of the disk, the shapes of the portions  138  and  144  and the edges  142  and  145  must also be chosen to meet the fly height requirements at all skew angles and disk linear velocities between the inner and outer diameters of the disk, and not only at the inner and outer diameters of the disk. According to the embodiments of the present invention, the shapes of the portions  138  and  144  and the edges  142  and  145  are designed to provide optimized effective lengths for the ramps  114  and  118  and the respective pads  116  and  120  across the entire sweep of skew angles of the slider  100 , from the inner diameter to the outer diameter of the disk, to balance the effects of variations in the linear velocity of the disk and the effective lengths of the ramps  114  and  118  and the pads  116  and  120  to maintain constant fly height for the slider  100 . For example, in a disk drive where the inner to outer skew angles are symmetrical, the maximum pressure for the inner pad  116  shown in FIG. 1 will be at the landing zone and will gradually decrease as the slider  100  is actuated toward the outer diameter of the disk. An examination of the shape of the edge  142  shows that the effective length of the ramp  114  is gradually reduced as one traces the air flow direction across the ramp  114  and the pad  116  at the various skew angles as the slider  100  is actuated from the inner diameter to the outer diameter of the disk. 
     Similarly, the minimum effective ramp length for the ramp  118  shown in FIG. 1 will be at the outer diameter and will gradually increase as the slider  100  is actuated toward the inner diameter of the disk. Accordingly, the effect of higher linear velocities is balanced by the reduced effective ramp and pad lengths at the outer diameter of the disk to maintain constant fly height of the slider  100 . 
     An examination of the shape of the edge  145  shows that the effective length of the ramp  118  is gradually increased as one traces the air flow direction across the ramp  118  and the pad  120  at the various skew angles as the slider  100  is actuated from the outer diameter to the inner diameter of the disk. 
     According to a further embodiment of the present invention, the air bleed slots  122  and  124  enable a larger positive pressure to develop underneath the trailing edge pads  116  and  120  than would be the case if the air bleed slots  122  and  124  were not present. One factor that is believed to contribute to causing the large positive pressure to build up underneath the trailing edge pads  116  and  120  is increased air flow across the trailing edge ramps  114  and  118  that is made possible by the presence of the air bleed slots  122  and  124 . The pressure differential between the positive-pressure outer border region  126  and the negative pressure cavity  136  is believed to be directing air flowing along the outer border region  136  at the sides  106  and  108  of the slider  100  toward the trailing edge ramps  114  and  118 . The increased air flow is then converged by the ramps  114  and  118  to provide increased positive pressure underneath their respective pads  116  and  120 . 
     Another factor that is believed to contribute to the increased pressures underneath the trailing edge pads is that the air bleed slots  122  and  124  vent the negative pressure cavity  136  to higher, positive pressures at the leading edge  138  of the ramp  114  and at the leading edge  144  of the ramp  118 . That is, the negative pressure of the cavity  136  is vented to near ambient pressure directly in front of the ramps  114  and  118 . The magnitude of the positive pressures at the leading edges  138  and  144  of the ramps  114  and  118  depends on the extent of the separation between the legs  130  and  132  of the leading edge pad  112  and the leading edges  138  and  144  of the trailing edge ramps  114  and  118 . As a result, the air flow that is compressed by the respective step ramps  114  and  118  to provide further positive pressure under each of the respective trailing edge pads  116  and  120  starts out at a higher pressure than if the air bleed slots  122  and  124  were not present. Consequently, the trailing edge  104  of the slider  100  separates from the magnetic media disk more quickly than is possible with prior art slider designs, thereby causing the slider  100  to be substantially flat as it lifts off from the landing zone of the magnetic media disk and reducing the pitch of the slider  100  as it flies over the magnetic media disk. Significantly, the advantages provided by the air bleed slots  122  and  124  are achieved without sacrificing the benefits that are provided by the negative pressure cavity  136 . 
     According to a further embodiment of the present invention, the air bleed slots  122  and  124  also enable the creation of a discrete pressure profile for each of the pads  112 ,  116 , and  120  as the slider  100  sweeps from the inner diameter to the outer diameter of the magnetic media disk. In prior art rail-type air bearing slider designs, the pressure profile at the trailing edge of the slider is coupled to the pressure profile at the leading edge of the slider because the rails of the slider extend from the leading edge to the trailing edge of the slider. In sliders according to the preferred embodiments of the present invention, the presence of the air bleed slots  122  and  124  enables a slider designer to tailor desired pressure profiles for the pads  112 ,  116 , and  120  that are not coupled to one another as the slider sweeps from the inner diameter to the outer diameter of the magnetic media disk. One advantage provided by the ability to independently adjust the pressure profiles for the pads  112 ,  116 , and  120  is the improved ability to balance the roll of the slider. In accordance with the embodiments of the present invention, the slider designer can more effectively tailor the pressure profiles at the front and back corners of the slider so that the slider flies substantially flat, thereby reducing the slider&#39;s roll. 
     According to an even further embodiment of the present invention, the outer border region  126  may serve as a“pre-ramp” to provide initial pressurization of air flow incident on the slider  100 . The outer border region  126  is etched to be approximately 15 microns wide and approximately 1-4 microns deep, and is formed by the additive etches of the shallow step ramps  110 ,  114 , and  118  and the deep cavity  136 . The outside edges of the outer border region  126  are blended during the process of etching the step ramps  110 ,  114 , and  118  and the cavity  136 . This improves the reliability of the slider  100  because the blending process removes sharp corners that might otherwise chip during normal operation of the slider  100 . The inventors have discovered that, for a particular slider according to the embodiments of the present invention, if the outer border region  126  preceding the leading edge ramp  110  is removed, the slider&#39;s change in pitch across the inner diameter of the disk to the outer diameter of the disk can decrease from 5 microns to 1 micron. This result leads the inventors to believe that the outer border region  126  does indeed serve as a pre-ramp to help converge incident air flow to the slider air bearing pads  100 . 
     The designer achieves the desired pressure profiles by selecting appropriate shapes for the leading and trailing edge ramps and their associated pads that optimize the effective areas of the ramps and their respective pads to provide the desired pressure profiles. FIGS. 4-7 show several exemplary sliders according to embodiments of the present invention. The sliders shown in FIGS. 4-7 show some of the different shapes that are possible for the leading edge pad of a slider according to the embodiments of the present invention. Referring to FIG. 4, the slider, generally designated  400 , has a leading edge step ramp  410 , a leading edge pad  412 , an inner trailing edge ramp/pad combination, generally designated  414 , and an outer trailing edge ramp/pad combination, generally designated  414 . The inner and outer trailing edge ramp/pad combinations will be described in more detail with respect to FIGS. 8A-8D and  9 A- 9 D. The leading edge pad  412  and the inner trailing edge ramp/pad combination  414  define an inner air bleed slot  422 . Likewise, the leading edge pad  412  and the outer trailing edge ramp/pad combination  418  define an outer air bleed slot  424 . The slider  400  also includes an outer border region  426  around its perimeter. 
     FIG. 5 shows an air bearing slider, generally designated  500 , which includes a leading edge ramp  510 , a leading edge pad  512 , an inner trailing edge ramp/pad combination  514 , and an outer trailing edge ramp/pad combination  518 . The leading edge pad  512  and the inner trailing edge ramp/pad combination  514  define an inner air bleed slot  522 . Likewise, the leading edge pad  512  and the outer trailing edge ramp/pad combination  518  define an outer air bleed slot  524 . The slider  500  also includes an outer border region  526  around its perimeter. 
     FIG. 6 shows an air bearing slider, generally designated  600 , which includes a leading edge ramp  610 , a leading edge pad  612 , an inner trailing edge ramp/pad combination  614 , and an outer trailing edge ramp/pad combination  618 . The leading edge pad  612  and the inner trailing edge ramp/pad combination  614  define an inner air bleed slot  622 . Likewise, the leading edge pad  612  and the outer trailing edge ramp/pad combination  618  define an outer air bleed slot  624 . The slider  500  also includes an outer border region  626  around its perimeter. 
     FIG. 7 shows an air bearing slider, generally designated  700 , which includes a leading edge ramp  710 , a leading edge pad  712 , an inner trailing edge ramp/pad combination  714 , and an outer trailing edge ramp/pad combination  718 . The leading edge pad  712  and the inner trailing edge ramp/pad combination  714  define an inner air bleed slot  722 . Likewise, the leading edge pad  712  and the outer trailing edge ramp/pad combination  718  define an outer air bleed slot  724 . The slider  700  also includes an outer border region  726  around its perimeter. 
     The embodiments of the sliders shown in FIGS.  1  and  4 - 7  all use leading edge pads that have a generally horseshoe shape. According to an embodiment of the present invention, this generally horseshoe shape enables continuous optimization of the pressure underneath the leading edge pad of the slider for the entire range of skew angles from the inner diameter to the outer diameter of the magnetic media disk. Those having skill in the art will appreciate that, since the skew angle of the slider  100  changes as the slider  100  moves from the inner diameter of the disk to the outer diameter of the disk, the shapes of the leading edge pad  112  and its contour  128  must also be chosen to meet the fly height requirements at all skew angles and disk linear velocities between the inner and outer diameters of the disk, and not only at the inner and outer diameters of the disk. According to the embodiments of the present invention, the shapes of the leading edge pad  112  and its contour  128  are designed to provide optimized effective lengths for the ramp  110  and the respective pad  112  across the entire sweep of skew angles of the slider  100 , from the inner diameter to the outer diameter of the disk, to balance the effects of variations in the linear velocity of the disk and the effective lengths of the ramp  110  and pad  112  to maintain constant fly height for the slider  100 . Thus, the slider designer can tailor the shape of the leading edge pad to ensure that the effective length of the leading edge pad and its preceding ramp presented to the air flow incident to the leading edge pad at each skew angle of the slider results in the desired pressure underneath the leading edge pad as the slider moves from the inner diameter to the outer diameter of the magnetic media disk. 
     FIGS. 8A-8D show several exemplary embodiments of outer trailing edge ramp/pad combinations for air bearing sliders according to embodiments of the present invention. In the ramp/pad combination  800  shown in FIG. 8A, the shapes of the ramp  802  and the pad  804  and the orientation of the leading edge  806  of the pad  804  are chosen such that an air flow vector representing the air flow incident on the ramp  802  is substantially orthogonal to the leading edge  806  when the slider is at a maximum negative skew angle at the inner diameter of the disk. In the ramp/pad combination  810  shown in FIG. 8B, the shapes of the ramp  812  and the pad  814  and the orientation of the leading edge  816  of the pad  814  are chosen such that an air flow vector representing the air flow incident on the ramp  812  is substantially orthogonal to the leading edge  816  when the slider is at a negative skew angle that is between zero and the maximum negative skew angle. In the ramp/pad combination  820  shown in FIG. 8C, the shapes of the ramp  822  and the pad  824  and the orientation of the leading edge  826  of the pad  824  are chosen such that an air flow vector representing the air flow incident on the ramp  822  is substantially orthogonal to the leading edge  826  when the slider is at zero skew angle. In the ramp/pad combination  830  shown in FIG. 8D, the shapes of the ramp  832  and the pad  834  and the orientation of the leading edge  836  of the pad  834  are chosen such that an air flow vector representing the air flow incident on the ramp  832  is substantially orthogonal to the leading edge  836  when the slider is at either a negative skew angle at the inner diameter of the disk or a positive skew angle at the outer diameter of the disk. 
     FIGS. 9A-9D show several exemplary embodiments of inner trailing edge ramp/pad combinations for air bearing sliders according to embodiments of the present invention. In the ramp/pad combination  900  shown in FIG. 9A, the shapes of the ramp  902  and the pad  904  and the orientation of the leading edge  906  of the pad  904  are chosen such that an air flow vector representing the air flow incident on the ramp  902  is substantially orthogonal to the leading edge  906  when the slider is at a maximum positive skew angle at the outer diameter of the disk. In the ramp/pad combination  910  shown in FIG. 9B, the shapes of the ramp  912  and the pad  914  and the orientation of the leading edge  916  of the pad  914  are chosen such that an air flow vector representing the air flow incident on the ramp  912  is substantially orthogonal to the leading edge  916  when the slider is at a positive skew angle that is between zero and the maximum positive skew angle. In the ramp/pad combination  920  shown in FIG. 9C, the shapes of the ramp  922  and the pad  924  and the orientation of the leading edge  926  of the pad  924  are chosen such that an air flow vector representing the air flow incident on the ramp  922  is substantially orthogonal to the leading edge  926  when the slider is at zero skew angle. In the ramp/pad combination  930  shown in FIG. 9D, the shapes of the ramp  932  and the pad  934  and the orientation of the leading edge  936  of the pad  934  are chosen such that an air flow vector representing the air flow incident on the ramp  932  is substantially orthogonal to the leading edge  936  when the slider is at either a positive skew angle at the outer diameter of the disk or a negative skew angle at the inner diameter of the disk. 
     As shown in FIGS. 8A-8D and  9 A- 9 D, the slider designer can tailor the shape of the outer and inner edge pads and their preceding ramps to ensure that the effective areas of the trailing edge pads and their preceding ramps presented to the air flow incident to the trailing edge pads at particular skew angles of the slider result in the desired pressure underneath the trailing edge pads to maintain fly height as the slider moves from the inner diameter to the outer diameter of the magnetic media disk. Thus, the slider designer can shape the trailing edge pads and their respective ramps to optimize the pressure underneath each of the trailing edge pads as a function of the slider&#39;s skew angle. 
     The air bearing sliders according to the embodiments of the present invention have many advantages, including improved take-off velocity, decreased change in pitch from the inner diameter of the disk to the outer diameter of the disk, and pressure profiles for the pads of the slider that not coupled to one another. In preferred embodiments of the present invention, the ratio of the shallow etch depth of the leading and trailing edge ramps to the deep etch depth of the negative pressure cavity  136  can be advantageously varied to improve the take-off velocity of the slider. A slider designer can vary this ratio to effect a desired balance between the take-off velocity and the altitude sensitivity of the slider. 
     In further preferred embodiments according to the present invention, air bleed slots enable a larger positive pressure to develop underneath the trailing edge pads than would be the case if the air bleed slots were not present. The presence of the air bleed slots advantageously allows the trailing edge of the slider to separate from the magnetic media disk more quickly than is possible with prior art slider designs, thereby causing the slider to be substantially flat as it lifts off from the landing zone of the magnetic media disk and reducing the pitch of the slider as it flies over the magnetic media disk. Referring to FIG. 10A, curve  1010  represents the pitch of the slider  100  shown in FIG. 1, and curve  1020  represents the pitch of the prior art rail-type slider shown in FIG. 11, as a function of the magnetic media disk&#39;s rotational velocity. As shown in FIG. 10A, the pitch of the slider  100  is considerably reduced in the landing zone over the rail-type slider shown in FIG.  11 . 
     In even further preferred embodiments according to the present invention, the shapes of the pads and their respective ramps are designed to provide the largest effective areas for the ramps and the pads at the maximum negative skew angle of the slider at the landing zone of the disk to overcome the negative pressure generated at the cavity defined by the leading edge pad, thereby improving the take-off velocity of the slider by achieving a large net positive pressure at a low rotational velocity of the disk. In general, according to the embodiments of the present invention, the slider designer can advantageously tailor desired pressure profiles for the leading and trailing edge pads of the slider that are independent of one another as the slider sweeps from the inner diameter to the outer diameter of the disk. The designer can achieve the desired pressure profiles by selecting shapes for the leading and trailing edges pads and their respective ramps that optimize the effective areas of the pads and their respective ramps to provide the desired pressure profiles for the pads of the slider. 
     The ability to independently tailor desired pressure profiles for the leading and trailing edge pads of the slider  100  enables the slider  100  to achieve better performance relating to roll, take-off velocity, and fly height performance. Referring to FIG. 10B, curve  1030  represents the roll of the slider  100 , and curve  1040  represents the roll of the rail-type slider shown in FIG. 11, as a function of the magnetic media disk&#39;s rotational velocity for a negative skew angle of 11°. As shown in FIG. 10B, the roll of the slider  100  remains substantially flat over the range of rotational velocities of the magnetic disk media. 
     Referring to FIG. 10C, curve  1050  represents the fly height of the center of gravity of the slider  100 , and curve  1060  represents the fly height of the center of gravity of the slider shown in FIG. 11, as a function of the magnetic media disk&#39;s rotational velocity. As shown in FIG. 10C, the increased fly height of the slider  100  over the prior art slider of FIG. 11 at lower rotational velocities indicates the increased take-off velocity of the slider  100 . 
     Referring to FIG. 10D, curve  1070  represents the fly height of the transducer that is-supported by the slider  100 , and curve  1080  represents the fly height of the transducer supported by the slider shown in FIG. 11, as a function of the rotational velocity of the magnetic media disk. As shown in FIG. 10D, the increased fly height of the slider  100  over the prior art slider of FIG. 11 at lower rotational velocities indicates the increased take-off velocity of the slider  100 . Furthermore, the fly height of the transducer of the slider  100  remains substantially flat over the range of rotational velocities of the magnetic media disk. In fact, a close examination of curve  1070  reveals that the fly height of the transducer of the slider  100  is lower at the disk&#39;s operating rotational velocity (in the case of FIGS. 10A-10D, 7200 rpm) than at lower rotational velocities. 
     Finally, the improved take-off velocity of the slider  100  reduces the wear of the interface between the slider by reducing the time (or the number of rotations) during which the slider is in contact with the magnetic media disk. 
     Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.