Patent Abstract:
A method and apparatus for removing a pad adhesively secured to a platen. The apparatus includes a barrel assembly having a clamp assembly fixedly attached to a perimeter of the barrel assembly; a rotatable handle assembly nested within the barrel assembly; and a ratchet assembly nested between the handle assemble and the barrel assembly the ratchet assembly configured to engage the rotatable handle assembly.

Full Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of chemical-mechanical polishing (CMP); more specifically, it relates to an apparatus for removing a pad from a platen and a method for removing a pad from a platen. 
     BACKGROUND 
     CMP is a process by which a substrate is placed against a rotating polishing pad while abrasive slurry is applied to the pad in order to etch/polish the substrate flush. Because of the forces involved the pad is adhesively (but removeably) secured to the platen making removal difficult. Because of the large size of the pad and strength of the adhesive various pad removal tools have been proposed. However, they do not work on CMP tools having recessed platens, must be attached to the CMP tool or present difficulties in removing the pad from the pad removal tool. Accordingly, there exists a need in the art to eliminate the deficiencies and limitations described hereinabove. 
     SUMMARY 
     A first aspect of the present invention is an apparatus, comprising: a barrel assembly having a clamp assembly fixedly attached to a perimeter of the barrel assembly; a rotatable handle assembly nested within the barrel assembly; and a ratchet assembly nested between the handle assembly and the barrel assembly, the ratchet assembly configured to engage the handle assembly. 
     A second aspect of the present invention is a method of removing a pad that is adhesively secured to a platen from the platen, comprising: placing a pad removal tool on the pad, the pad removal tool comprising: a barrel assembly having a clamp assembly fixedly attached to a perimeter of the barrel assembly; a rotatable handle assembly nested within the barrel assembly; and a ratchet assembly nested between the rotatable handle assembly and the barrel assembly, the ratchet assembly configured to engage the rotatable handle assembly; aligning the clamp assembly, the barrel assembly, the ratchet assembly and the rotatable handle assembly along a line passing through a center of the pad; clamping an edge of the pad in the clamp assembly; using the handle and the ratchet assembly, applying a force in a direction parallel to the line to rotate the barrel assembly in the direction and to roll a less than whole portion of the polishing pad onto the barrel assembly; and completely removing the pad from the platen. 
     These and other aspects of the invention are described below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features of the invention are set forth in the appended claims. The invention itself, however, will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is an isometric view of an apparatus for removing an adhesively secured pad according to an embodiment of the present invention; 
         FIG. 2  is an internal view of the apparatus of  FIG. 1  illustrating the various components of the apparatus in more detail; 
         FIG. 3  is an internal side view of the apparatus of  FIG. 1  illustrating a first position of the ratchet mechanism; 
         FIG. 4  is an internal side view of the apparatus of  FIG. 1  illustrating a second position of the ratchet mechanism; 
         FIG. 5  is an internal side view of the apparatus of  FIG. 1  illustrating a third position of the ratchet mechanism; 
         FIG. 6  is a top view of a CMP tool with the pad removal tool of  FIG. 1  in a starting position; 
         FIGS. 7A through 7G  are side views illustrating the various steps in using the apparatus of  FIG. 1  to remove a pad from a platen; 
         FIG. 8  is a flowchart of the steps to remove a pad from a platen according to an embodiment of the present invention; and 
         FIG. 9  is an internal view of an alternate embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is an isometric view of an apparatus for removing an adhesively secured pad according to an embodiment of the present invention. In  FIG. 1 , pad removal tool  100  includes a barrel assembly  101 , a handle assembly  102 , a ratchet assembly  103  and a clamp assembly  104 . Barrel assembly  101  includes a side plate  105 A and an opposite and similar side plate  105 B having major surfaces facing each other and fixedly connected by rods  110 ,  115 ,  120 ,  125  and  130 . Handle assembly  102  includes an L-shaped arm  140 A and an opposite and similar L-shaped arm  140 B having major surfaces facing each other and fixedly connected by rods  145  and a handle  155 . Each L-shaped arm has a first member extending inside of barrel assembly  101  and a second member extending outside of barrel assembly  101 . Ratchet assembly  103  includes a ratchet plate  165 A and an opposite and similar ratchet plate having major surfaces facing each other and fixedly connected by rods  170  and  175 . Handle assembly  102  is nested within barrel assembly  101  and ratchet assembly  103  is nested within handle assembly  102 . Because rods  170  and  175  do not extend past ratchet plates  165 A and  165 B, arms  140 A and  140 B are free to move between ratchet assembly  103  and barrel assembly  101 . 
     In one example, rods  110 ,  115 ,  120 ,  125 ,  130 ,  145 ,  170  and  175  are fabricated from stainless steel and side plates  105 A and  105 B, arms  140 A and  140 B, and ratchet sides  140 A and  140 B are fabricated from anodized aluminum reducing weight. In one example, clamp assembly  104  may be fabricated from commercially available locking pliers, such as Vise-Grip™ (i.e., model 8R) manufactured by Irwin Industrial Tool Company of Huntsville, N.C. 
       FIG. 2  is an internal side view of the apparatus of  FIG. 1  illustrating the various components of the apparatus in more detail. In  FIG. 2 , side plate  105 A is attached to the aforementioned rods  110 ,  115 ,  120 ,  125  and  130  and includes a stop pin  135 . Arm  140 A is attached to the aforementioned rod  145  and handle  155  and further includes a hole  150  through which rod  110  passes. Thus, arm  140 A is free to rotatable about rod  110 , but is stopped from 360° rotation by rod  130  on which arm  140 A is shown resting on. Ratchet plate  165 A is attached top the aforementioned rods  170  and  175  and includes a hole  180  through which rod  130  passes. Thus, ratchet plate  165 A is free to rotate about rod  130 , but is stopped from 360° rotation by rod  145  on which ratchet plate  165 A is shown resting on and by a pin  135  in side  105 A. Ratchet plate  165 A also includes a first notch  185  closet to hole  180  and a second notch  190  furthest from hole  180 . A hole  192  in ratchet plate  165 A allows connection of a spring  195  between ratchet plate  165 A and rod  125 . Spring acts to hold ratchet plate  165 A against rod  145 . 
     An internal view toward side plate  105 B, arm  140 B and ratchet plate  165 B (see  FIG. 1 ) would present a minor image of  FIG. 2  and include a second spring  195 . Turning to clamp assembly  104  of  FIG. 2 , clamp assembly  104  includes a fixed jaw  200  fixedly attached to rod  115  and a movable jaw  205  rotatable about rod  115 . Movable jaw  205  is moved toward fixed jaw  200  by a handle  210  that is hinged to movable jaw  205 . An adjustment screw  215  in a handle  220  (that is also fixedly attached to rod  115 ) allows adjustment of the clamping force between fixed jaw  200  and movable jaw  205 . A lever  225  in handle  210  allows the clamping force to be released. 
       FIG. 3  is an internal side view of the apparatus of  FIG. 1  illustrating a first position of the ratchet mechanism.  FIG. 3  is similar to  FIG. 2  except the dashed lines have been removed and some of the reference numerals to more clearly show the interaction of handle assembly  102  with ratchet assembly  103 . It should be understood that the positions and movements of arm  140 A and ratchet plate  165 A are duplicated by  140 B and ratchet plate  165 B (not shown). In the first position, arm  140 A rests on rod  180  and a bottom edge of ratchet plate  165 A between first notch  185  and hole  180  rests against rod  145 . Moving handle assembly  102  in the direction indicated on arm  140 A will cause a corresponding force on rod  130  causing the entire pad removal tool  100  to rotate about rod  110  in the clockwise direction indicated on side plate  105 A. 
       FIG. 4  is an internal view of the apparatus of  FIG. 1  illustrating a second position of the ratchet mechanism. In  FIG. 4 , handle assembly  102  was rotated counter-clockwise about rod  110  while holding barrel assembly  101  in the same position as in  FIG. 3  (i.e., while not rotating the barrel assembly) until rod  145  engages first notch  185  in ratchet plate  165 A. Ratchet plate  165 A has also rotated about rod  130  while arm  140 A was rotated. Moving handle assembly  102  in the direction indicated on arm  140 A will cause a corresponding force on rod  145  which is transmitted to rod  130  through ratchet plate  165 A causing the entire pad removal tool  100  to rotate about rod  110  in the clockwise direction indicated on side plate  105 A. 
       FIG. 5  is an internal side view of the apparatus of  FIG. 1  illustrating a third position of the ratchet mechanism. In  FIG. 5 , handle assembly  102  was rotated counter-clockwise about rod  110  while holding barrel assembly  101  in the same position as in  FIG. 4  (i.e., while not rotating the barrel assembly) until rod  145  engages second notch  190  in ratchet plate  165 A. (Note the entire  FIG. 5  has been rotated to fit on the drawing sheet.) Ratchet plate  165 A has also rotated about rod  130  while arm  140 A was rotated. Moving handle assembly  102  in the direction indicated on arm  140 A will cause a corresponding force on rod  145  which is transmitted to rod  130  through ratchet plate  165 A causing the entire pad removal tool  100  to rotate about rod  110  in the clockwise direction indicated on side plate  105 A. 
       FIG. 6  is a top view of a CMP tool  250  with the pad removal tool of  FIG. 1  in a starting position. In  FIG. 6 , a CMP tool  250  includes a raised deck  255  around a well  260  with a platen  265  or polishing well positioned therein. Platen  265  can rotate around a center axis. CMP tool  250  also includes a polishing head  270  suspended from a moveable arm assembly  275  for holding and rotating circular wafers (the substrate used in semiconductor processing) that are pressed into a polishing pad  280  that is adhesively secured to platen  265 . CMP tool  250  also includes means (not shown) for dispensing a chemical etchant and abrasive slurry onto polishing pad  280 . CMP tool  250  may also includes means (not shown) for dispensing rinse solution onto polishing pad  280 . In  FIG. 6 , arm assembly  275  is rotated out of the way preparatory to removing polishing pad  280 . Pad removal tool  100  is placed centered along an axis  285  that passes through the center of platen  265  so as to eliminate or minimize rotational force on platen  265  during the pad removal process. The pad is to be removed in the direction indicated by the arrow. 
     Polishing pad  280  has a diameter PD. Pad removal tool  100  had a diameter D and a width W. It is preferred that W be selected to be wide enough to provide a stable footing (not easily tilted side to side) for barrel assembly  101  and yet be narrow enough to allow clamp assembly to be close (with a couple of inches) of the edge of polishing pad  280  (see  FIG. 7A ). It is preferred that W be selected to be large enough to have most of the removed pad wrapped around barrel assembly  101  after removal without the pad overlapping itself, yet be small enough to leave as little pad still attached to the platen as possible (see  FIG. 7E ). In one example, the ratio of W/PD is between about 0.20 and about 0.30 with about 0.25 preferred. In one example, the ratio of D/PD is between about 0.4 and about 0.6 with about 0.5 preferred. For polishing pads intended to CMP 200 mm diameter wafers PD is about 22 inches, making D about 10 inches and W about 5 inches. For polishing pads intended to CMP 300 mm diameter wafers PD is about 30 inches, making D about 15 inches and W about 7.5 inches. 
       FIGS. 7A through 7G  are side views illustrating the various steps in using the apparatus of  FIG. 1  to remove a pad from a platen. The term “manually” is defined as a person using their hands to place the pad removal tool on the polishing pad, to grasp the polishing pad, to clamp the polishing pad, to apply a force to the handle of the pad removal tool by pulling or pushing on the handle of the pad removal tool, and to remove the pad removal tool from the CMP tool. In  FIG. 7A , an edge of polishing pad  280  has been pulled up manually (about 10% of the total pad area) and manually clamped into clamp assembly  104 . Pad removal tool  100  is internally set as illustrated in  FIG. 2  and handle assembling  102  is manually pulled clockwise to rotate barrel assembly  101  in the clockwise direction. This results in the orientation of pad  280  and pad removal tool  100  shown in  FIG. 7B . 
     In  FIG. 7B , about a 35% of the total pad area of polishing pad  280  has been pulled from platen  265  and wrapped on barrel  101  by manually pulling on handle  155  (see  FIG. 1 ) of arm assembly  102 . Pulling of arm assembly  102  has stopped prior to the arm assembly hitting polishing pad  265 . Arm assembly  102  is then rotated counterclockwise to internally set pad removal tool  100  as illustrated in  FIG. 4  (rod  145  is engaged in notch  185 ) by manually pushing on handle  155  (see  FIG. 1 ) of handle assembly  101 . This results in the orientation of pad  280  and pad removal tool  100  shown in  FIG. 7C . 
     In  FIG. 7C , handle assembly  102  is again manually pulled in the clockwise direction resulting in the orientation of pad  280  and pad removal tool  100  shown in  FIG. 7D . In  FIG. 7D , about 60% of the total area of polishing pad  280  has been pulled from platen  265  and wrapped on barrel  101 . Pulling of arm assembly  102  has stopped prior to the arm assembly hitting polishing pad  265 . Arm assembly  102  is then rotated counterclockwise to internally set pad removal tool  100  as illustrated in  FIG. 5  (rod  145  is engaged in notch  190 ) by again manually pushing on handle  155  (see  FIG. 1 ) of the handle assembly. This results in the orientation of pad  280  and pad removal tool  100  shown in  FIG. 7E . 
     In  FIG. 7E , handle assembly  102  is again manually pulled in the clockwise direction resulting in the orientation of pad  280  and pad removal tool  100  shown in  FIG. 7F . In  FIG. 7F , at least about 80% of the total area of polishing pad  280  has been pulled from platen  265  and wrapped on barrel  101 . Pulling of arm assembly  102  has stopped prior to the arm assembly hitting polishing pad  265 . The area of polishing pad  280  still attached to platen  265  is small enough to complete removal by simply manually lifting pad removal tool  100  and the attached polishing pad away from CMP tool  255  as illustrated in  FIG. 7G . Alternatively, the pad may be unclamped, the pad removal tool removed, and the pad removed manually. Note, in  FIG. 7G , polishing pad  280  is not completely wrapped around barrel assembly  101  and not wrapped around itself, making removal of polishing pad  280  from pad removal tool  100  easy. 
       FIG. 8  is a flowchart of the steps to remove a pad from a platen according to an embodiment of the present invention. In step  300 , an operator raises the edge of the polishing pad from the platen and places the pad removal tool of the present invention placed on the polishing pad as illustrated in  FIG. 6 . In step  305 , the operator clamps the pulled up edge of the polishing pad to the pad removal tool using the clamp assembly as in  FIG. 7A . Internally, the ratchet assembly is set as in  FIG. 3 . In step  310 , the operator rotates the barrel assembly in a first direction using the arm assembly as in  FIG. 7B . In step  315 , the operator rotates the arm assembly in a second direction opposite to the first direction as in  FIG. 7C  to set the ratchet assembly as in  FIG. 4 . In step  320 , the operator rotates the barrel assembly in the first direction using the arm assembly as in  FIG. 7D . In step  325 , the operator rotates the arm assembly in the second direction as in  FIG. 7E  to set the ratchet assembly as in  FIG. 5 . In step  330 , the operator rotates the barrel assembly in the first direction using the arm assembly as in  FIG. 7E . In step  335 , the operator lifts the pad removal tool from the polishing tool thus removing the remainder of the polishing pad from the plate as in  FIG. 7G . Then the polishing pad is removed from the pad removal tool by releasing the clamp assembly. 
       FIG. 9  is an internal view of an alternate embodiment of the present invention. In  FIG. 9 , a pad removal tool  100 A is similar to pad removal tool  100  of  FIG. 2  except a barrel assembly  101 A includes oval (oval is defined to include elliptical) side plate  105 AA and an opposite oval side plate  105 BA (not shown). Rod  110  attaches the geometric center of side plate  105 AA to the geometric center of side plate  105 BA (not shown). Side plate  105 AA has a major axis  350  and a minor axis  355 . The width of side plate  105 AA is greater along axis  350  then along axis  355 . In a second alternative embodiment, side plate  105 AA is rotated 90° without rotating any other elements of  FIG. 9  so the positions of the major and minor axes are exchanged. 
     While the ratchet assembly has been illustrated having three positions (and two notches), the ratchet assembly may have more than three positions (and more than two notches). 
     The descriptions of the various embodiments of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

Technology Classification (CPC): 8