Abstract:
An apparatus includes a slider body having a leading edge and an opposite trailing edge, as well as a top face and a bottom face each extending between the leading edge and the trailing edge. The slider body further includes a plurality of protrusions extending from the bottom face, a first recess defined on one of the protrusions, and a sacrificial layer deposited on the slider body in the recess. A bottom surface of the sacrificial layer extends at least as far from the bottom face as bottom surfaces of the plurality of protrusions. In another aspect, a first blocking feature is located at a first uptrack edge on an air bearing surface of a slider, with the first blocking feature being substantially continuous along the first uptrack edge and protruding outwardly from the air bearing surface to reduce particle interaction with the air bearing surface.

Description:
BACKGROUND 
     In data storage systems, including hard disc drives (HDDs), slider-disc contact can cause scratching of the magnetic storage medium and can lead to data loss. Further, particles generated by scratching can lead to latent data loss or other decreases in HDD performance. Particles can also be generated in other ways. One particular problem is that particles can accumulate on surfaces inside the HDD and later shed to the magnetic storage media, increasing a risk of unwanted magnetic erasures or other forms of performance degradation. 
     It is desired to limit the creation of particles in a data storage system in the first instance, and further, or in the alternative, to reduce undesired effects of any particles that are present. 
     SUMMARY 
     An apparatus according to one aspect of the present invention includes a slider body having a leading edge and an opposite trailing edge, as well as a top face and a bottom face each extending between the leading edge and the trailing edge. The slider body further includes a plurality of protrusions extending from the bottom face, a first recess defined on one of the protrusions, and a sacrificial layer deposited on the slider body in the recess. A bottom surface of the sacrificial layer extends at least as far from the bottom face as bottom surfaces of the plurality of protrusions. 
     In another aspect of the present invention, a method includes creating a plurality of protrusions that collectively define an air bearing surface of a slider, milling a recess at the air bearing surface to a depth D, and depositing a sacrificial material in the recess to a thickness equal to or greater than the depth D. 
     In yet another aspect of the present invention, an apparatus includes a slider body having a leading edge and an opposite trailing edge, as well as a top surface and a bottom surface each extending between the leading edge and the trailing edge, an air bearing surface protruding outwardly from a portion of the bottom surface and having a first uptrack edge proximate the leading edge, and a first blocking feature located at a first uptrack edge on the air bearing surface. The first blocking feature is substantially continuous along the first uptrack edge and protruding outwardly from the air bearing surface to reduce particle interaction with the air bearing surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is an air bearing surface (ABS) view of a slider according to the present invention. 
         FIG. 1B  is a cross-sectional view of the slider, taken along line  1 B- 1 B of  FIG. 1A . 
         FIG. 2  is a cross-sectional view of another slider according to the present invention. 
         FIG. 3  is another ABS view of a slider according to the present invention. 
         FIG. 4  is a flow chart illustrating a method of manufacturing a slider according to the present invention. 
         FIG. 5A  is another ABS view of a slider according to the present invention. 
         FIG. 5B  is a cross-sectional view of the slider, taken along line  5 B- 5 B of  FIG. 5A , along with a portion of a storage medium. 
         FIG. 5C  is another ABS view of a slider according to the present invention. 
         FIG. 6  is another ABS view of a slider according to the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1A  is an air bearing surface (ABS) view of a slider  32  having a slider body  38  with a leading edge  40 , a trailing edge  42 , and opposite lateral edges  44  and  46 . For clarity, portions of the slider  32  in  FIG. 1A  are hatched to represent surfaces at different heights.  FIG. 1B  is a cross-sectional view of the slider body  38 , taken along line  1 B- 1 B of  FIG. 1A . The slider body  38  is typically made of a ceramic material, such as AlOTiC. A number of protrusions  48 ,  50  and  52  extend from the slider body  38 , and can be integral with the remainder of the slider body  38 . In the illustrated embodiment, the protrusion  52  forms a comb structure adjacent to the leading edge  40  of the slider body  38 . The protrusion  48  is located adjacent to the trailing edge  42  (and extends uptrack, such as relative to a storage medium track), and the protrusion  50  is located in between the protrusions  48  and  52 . The protrusions  48 ,  50  and  52  are noncontiguous (i.e., not contiguous with each other). For instance, the protrusion  52  is spaced from the protrusion  50 , with a cavity  54  defined therebetween. The cavity  54  refers to a region or regions lower than or recessed from an air bearing surface (ABS), and can have a uniform or varying depth. 
     In the illustrated embodiment, the protrusions  48  and  50  each have a bottom surface  56 . A recess  58  is formed in the protrusion  52 , which defines a recessed surface along substantially the entire protrusion  52  in the illustrated embodiment. The recess  58  has a depth D 1 . Also, as illustrated, another recess  60  is formed in the slider body  38  within the cavity  54 , and is located immediately adjacent to the recess  58  in the protrusion  52 . The recess  60  has a depth D 2 . In the illustrated embodiment, the depths D 1  and D 2  are substantially equal. In one embodiment, the depths D 1  and D 2  are each approximately 350 Å. In another embodiment, the depths D 1  and D 2  can each be less than or equal to about 450 Å. In still further embodiments, nearly any depths D 1  and D 2  can be utilized. 
     A sacrificial layer of material  62  is located on the slider body  38 . As illustrated in  FIGS. 1A and 1B , the sacrificial layer of material  62  is deposited on the slider body  38  within a rectangular area (i.e., having a substantially rectangularly shaped perimeter) that entirely encompasses the protrusion  52 . The sacrificial layer of material  62  includes a first portion  62 A and a second portion  62 B. The first portion  62 A is located in the recess  58 , and the second portion  62 B is located in the recess  60 . The first and second portions  62 A and  62 B each have a bottom surface  64 A and  64 B, respectively. A thickness of the first portion  62 A is substantially equal to the depth D 1  of the recess  58 , and a thickness of the second portion  62 B is substantially equal to the depth D 2  of the recess  60 . Alternatively, the thickness of the first and/or second portions  62 A and  62 B of the sacrificial layer of material  62  can be greater than the depths D 1  and D 2  of the recesses  58  and  60 , respectively. The sacrificial layer of material  62  can be made of amorphous coatings such as diamond-like carbon (DLC), SiO 2 , sputtered C and Al 2 O 3 . Table 1 summarizes elastic modulus and hardness values (in GPa) for certain materials that can be used in conjunction with the present invention. In general, the sacrificial layer of material  62  has a lower hardness and lower elastic modulus than the ceramic material of the slider body  38  (including the protrusions  48 ,  50  and  52 ). More particularly, the sacrificial layer of material  62  is typically made of a material with a lower Hertzian contact potential than the ceramic material of the slider body  38 . That relationship can also be assessed in terms of a plasticity index, and in some embodiments, a plasticity index for the sacrificial layer of material  62  is less than approximately 0.6. 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                   
                   
                 Sputtered 
                   
               
               
                   
                 DLC 
                 SiO 2   
                 Al 2 O 3   
                 Amorphous C 
                 AlOTiC 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Elastic modulus 
                 100 
                 70 
                 130 
                 90 
                 390 
               
               
                 (GPa) 
               
               
                 Hardness (GPa) 
                 15-22 
                 6.2 
                 9 
                 10-15 
                 29 
               
               
                   
               
             
          
         
       
     
     The respective bottom surfaces  56  of each of the protrusions  48  and  50  and the bottom surface  64 A of the portion  62 A of the sacrificial layer of material  62  on the protrusion  52  collectively define an ABS, and lie substantially within a single plane  66 . The illustrated configuration of the ABS is shown by way of example, and not limitation. Those of ordinary skill in the art will recognize that the particular configuration of protrusions  48 ,  50  and  52  that, at least in part, define the ABS can vary as desired for particular applications, and, for instance, the particular shapes, arrangements and sizes of each of the protrusions  48 ,  50  and  52  can be modified to produce desired flying characteristics of the slider body  38 . 
     Because the thickness of the first portion  62 A of the sacrificial layer of material  62  is substantially equal to the depth D 1  of the recess  58 , the sacrificial layer of material  62  extends to and partially defines the ABS. In that way, the sacrificial layer of material  62  in the recess  58  can essentially replace a desired amount of the ceramic material of the protrusion  52  while maintaining a given ABS configuration. The thicknesses of the first and second portions  62 A and  62 B of the sacrificial layer of material  62 , corresponding to the depths D 1  and D 2 , can be selected to accommodate and anticipated amount of wear over an expected life of the HDD  20 . In alternative embodiments, the thickness of the sacrificial layer of material  62  can be greater than the corresponding depth D 1  or D 2  of the recess  58  or  60  such that the sacrificial layer of material  62  protrudes above the ABS to provide performance benefits such as decreased particle sensitivity due to the blocking of particles from downtrack ABS features. 
     The presence of the sacrificial layer of material  62  in the recess  60  helps reduce a risk of any localized discontinuities (or “spikes”) along the ABS. Due to relatively small manufacturing tolerances, it may be possible for slightly non-planar discontinuities between the location of the bottom surfaces of the sacrificial layer of material  62  and the ceramic material of the slider body  38  surrounding the recess  60  to occur at the perimeter of the sacrificial layer of material  62 . Such discontinuities may undesirably lead to scratching of the storage medium  22 . However, by positioning the recess  60  within the cavity  54 , any potential discontinuity at the perimeter of the sacrificial layer of material  62  would be located within the cavity  54 , and therefore spaced from the ABS, which helps reduce a risk of such a discontinuity scratching the storage medium  22  during operation. 
       FIG. 2  is a cross-sectional view of a slider  32  (generally similar to that described above with respect to  FIGS. 1A and 1B ) in which the sacrificial layer of material  62  is deposited on the slider body  38  in the recess  58 , but not within the cavity  54 . Dashed lines indicate that in some embodiments the depth D 1  of the sacrificial layer of material  62  can extend beyond the ABS  66  to provide additional particle mitigation. 
       FIG. 3  is another ABS view of a slider  32 ′ having a slider body  38  with a configuration generally similar to that described above with respect to slider  32 , with portions of the slider  32 ′ hatched to represent surfaces at different heights for clarity. However, as illustrated in  FIG. 3 , a sacrificial layer of material  62 ′ is applied to recesses  58 ′ and  60 ′ in two discrete rectangular areas that each covers a portion of the protrusion  52  near corners of the slider body  38  at the leading edge  40 . Bottom surfaces of the sacrificial layer of material  62 ′ lie substantially within a single plane with surfaces of the protrusions  48  and  50 , as well as bottom surface portions of the protrusion  52  located adjacent to—but not covered by—the sacrificial layer of material  62 ′, in order to collectively define the ABS. By locating the sacrificial layer of material  62 ′ in discrete areas at corners of the slider  32 ′, the sacrificial layer of material  62 ′ is positioned in locations most likely to contact the storage medium  22  during extreme roll static attitude (RSA) and pitch static attitude (PSA) conditions, while reducing a total amount of the sacrificial material utilized. 
       FIG. 4  is a flow chart illustrating a method of manufacturing a slider. Initially, an ABS is formed on a slider body (step  100 ). The ABS can be formed using conventional techniques, such as photolithography, and milling ceramic material (e.g., AlOTiC) of the slider body to define a desired ABS configuration. Next, at least a portion of the ABS is milled to create one or more recesses in the ceramic material of the slider body (step  102 ). The milling at step  102  can be performed using known techniques. Then a fill material, that is, a sacrificial layer of material as described above, is deposited into the recesses milled at step  102  (step  104 ). Deposition can be performed using known techniques. The sacrificial layer of material can be filled to a thickness approximately equal to a depth of the recesses. The milling and filling of steps  102  and  104  can be performed over non-ABS regions of the slider body in addition to ABS regions. Moreover, in alternative embodiments, the sacrificial layer of material can be made to protrude above the ABS when filled in the recesses. Furthermore, it will be appreciated that additional manufacturing steps not specifically mentioned can be performed according to the present invention. 
       FIG. 5A  is an ABS view of a slider  132  having a slider body  138  with a leading edge  140 , a trailing edge  142 , and opposite lateral edges  144  and  146 , and  FIG. 5B  is a cross-sectional view of the slider  132 , taken along line  5 B- 5 B of  FIG. 5A , along with the storage medium  22  (which may include multiple layers not specifically shown, for simplicity). For clarity, portions of the slider  132  in  FIG. 5A  are hatched to represent surfaces at different heights. A number of protrusions  150 ,  151  and  152  extend from the slider body  138 , and can be integral with the remainder of the slider body  138 . In the illustrated embodiment, a portion of the protrusion  152  forms a comb structure  152 A adjacent to the leading edge  140 . The protrusions  150  and  151  are located in a generally middle region of the slider body  138 . An ABS is defined by surfaces of the protrusions  150 ,  151  and  152 , which are substantially coplanar. Cavities  154  are defined along the slider body  138  adjacent to uptrack edges  168  of at least portions of the protrusions  150 ,  151  and  152 , that is, adjacent to edges of the protrusions  150 ,  151  and  152  that are generally proximate or facing the leading edge  140 . The cavities  154  can have varying depths, and the particular configuration of the cavities  154  can vary as desired for particular applications. As illustrated, blocking features  170  and  172  (shown as heavy lines in  FIG. 5A ) are located on the protrusions  152  and  150 , respectively. More particularly, as illustrated, the blocking features  170  and  172  are located on ABS surfaces of the protrusions  152  and  150  at and aligned with the uptrack edges  168  thereof. The blocking feature  170  has a non-linear shape and extends laterally across substantially an entire width of the slider body  138  between the lateral edges  144  and  146 , at a location downtrack from the comb structure  152 A. The blocking feature  172  is substantially V-shaped and is positioned near the trailing edge  142 . The blocking features  170  and  172  can be made of DLC, which can be applied by selective, focused deposition using known techniques. Alternatively, the blocking features  170  and  172  could be made from other materials such as SiO 2 , sputtered C, and Al 2 O 3 . Alternatively, the blocking features  170  and  172  could be made integrally with the protrusions  150  and  152  by milling adjacent areas of the protrusions  150  and  152  to lower depths. In this respect, the blocking features  170  and  172  could be made without the deposition of additional material, but would require an additional milling step. 
     It should be understood that the particular location, shape, and other characteristics of the blocking features  170  and  172  can vary in further embodiments. For instance, few or greater numbers of blocking features can be provided on essentially any protrusions. The configurations of the blocking features  170  and  172  are shown merely by way of example and not limitation. 
     As shown in  FIG. 5B , the blocking features  170  and  172  each have a thickness T, such that the blocking features  170  and  172  extend from the ABS defined by the protrusions  150 ,  151  and  152 . In other words, as shown in  FIG. 5B , the blocking features  170  and  172  (only blocking feature  170  is visible in  FIG. 5B ) extend closer to the storage medium  22  than the ABS surface defined by surfaces of the protrusions  150 ,  151  and  152  (only the protrusion  152  is visible in  FIG. 5B ). The thickness T can be selected such that for a given fly pitch angle θ, the blocking features  170  and  172  are positioned closer to the storage medium  22  than downtrack surfaces of the protrusions  150  and  152 , without contacting the storage medium  22  and disturbing the fly pitch of the slider  132 . For example, the thickness T can be approximately 20 nm, 40 nm, 60 nm or have any other suitable value for particular applications. 
     It has been found that a clearance between the slider  132  and the storage medium  22  is a significant factor for particle sensitivity of transducing operation. The blocking features  170  and  172  help reduce the clearance between the slider  132  and the storage medium  22  to block particles from progressing downtrack along the ABS. During operation, the blocking features  170  and  172  help limit particle interaction with the ABS at downtrack locations by providing a physical barrier to particles having a diameter (or other major dimension) P or greater. In this way, the blocking features  170  and  172  provide focused particle blocking functionality at sensitive locations of the ABS, and can help block particles of diameter P that can pass by the comb structure  152 A. 
       FIG. 5C  is another ABS view of a slider  132 ′. The slider  132 ′ is generally similar to the slider  132  described above. However, the slider  132 ′ has a different ABS configuration defines by protrusions  150  and  152 ′. Blocking features  170  and  172 ′ are defined along edges of portions of the protrusions  150  and  172 ′, respectively. 
       FIG. 6  is another ABS view of a slider  232  having a slider body  238  with a leading edge  240 , a trailing edge  242 , and opposite lateral edges  244  and  246 . For clarity, portions of the slider  232  in  FIG. 6  are hatched to represent surfaces at different heights. A number of protrusions  250 ,  251 A,  251 B,  251 C and  252  extend from the slider body  238 , and can be integral with the remainder of the slider body  238 . In the illustrated embodiment, the protrusion  252  forms a comb structure at the leading edge  240 . The protrusions  250  and  251 A- 251 C are located in a generally middle region of the slider body  238 , with the protrusion  250  located adjacent to and dowtrack from the protrusion  252 . An ABS is defined by surfaces of the protrusions  250  and  251 A- 251 C, which are substantially coplanar. At least one cavity  254  is defined along the slider body  238  adjacent to an uptrack edge  268  of at least portions of the protrusion  250 , that is, adjacent to edges of the protrusion  250  that are generally proximate or facing the leading edge  240 . The cavity  254  can have varying depth, and the particular configuration of the cavity  254  can vary as desired for particular applications. As illustrated, pads  274 A and  274 B are located on the protrusion  252 , at generally opposite lateral ends of the protrusion  252 . The pads  274 A and  274 B can be made of a sacrificial layer of material, such as a material of the type described above, deposited on the protrusion  252 . The protrusion  252  can have a lower height than the protrusion  250 , and bottom surfaces of the pads  274 A and  274 B can be substantially co-planar with the ABS defined by bottom surfaces of the protrusions  250  and  251 A- 251 C. The protrusion  250  can define another comb for particle mitigation, such that the protrusions  250  and  252  form adjacent spaced-apart combs. The pads  274 A and  274 B can act as bumpers. The pads  274 A and  27 B can be spaced slightly from the extreme leading edge  240 , which can allow the slider  232  additional time to contact with a storage medium under negatively-pitched conditions. Moreover, the sacrificial layer of material forming the pads  274 A and  274 B can help mitigate storage medium scratching and particle generation. In particular, the location of the pads  274 A and  274 B near the corners of the slider body  238  (i.e., near the intersection of the leading edge  240  with the lateral edges  244  and  246 ) helps mitigate scratching and particle generation in locations where contact between the slider  232  and a storage medium is most likely to occur and otherwise would be potentially more detrimental due to the relatively sharp corners of the slider body  238 . 
     While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims. For example, the present invention can be utilized with ABS designs other than those illustrated in the appended drawings. Moreover, features of one disclosed embodiment of the present invention can be utilized separately from or in conjunction with features of any other disclosed embodiment.