Abstract:
A demounting apparatus is described which releases semiconductor work pieces from an adhesive support structure. The demounting apparatus includes a conduit with a pair of opposed openings. A support structure is placed over one of the openings with a work piece mounted on a lower surface thereof. A vacuum is exerted on the conduit through a constricted outlet, thereby creating a pressure differential. The lower pressure within the demounting apparatus causes the support structure to elastically deform, thereby reducing its adherence on the work piece. The work piece is dislodged from the support structure and caught by a cushion positioned in the other opening. The cushion is pushed inwardly by the pressure differential. Other structures for releasing the work piece are also disclosed.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the post processing stage in the manufacture of semiconductor work pieces. More particularly, the present invention relates to an apparatus and method for releasing work pieces from a mounting tape. 
     BACKGROUND OF THE INVENTION 
     Semiconductor work pieces, such as wafers, reticules, masks, frame leads, and integrated circuit packages are very small devices which are easily moved and even more easily broken. Conventionally, during processing, work pieces are adhered to a high adhesive tape, such as, for example, Nitto tape. After processing, the wafers are typically removed from the tape. It is imperative that the wafers be removed without being damaged, which is often difficult given that the adhesive tape used generally has high adherent characteristics. 
     There is, thus, a need in the industry for a low cost and effective method and apparatus for releasing work pieces from an adhesive material, for example, a tape without breaking the work piece. 
     SUMMARY OF THE INVENTION 
     The present invention provides a demounting apparatus which includes a conduit, a demounting mechanism, and a support structure having an adhered work piece which is to be removed. The conduit has a pair of opposed openings and a vacuum port. The demounting mechanism includes a vacuum source which exerts a vacuum through the vacuum port. The support structure is supported by the conduit and placed over one of the openings. The work piece is mounted on an undersurface of the support structure and the vacuum is exerted, causing the support structure to elastically deform. The deformation and the force of the vacuum combine to release the work piece from the support structure. 
     The present invention also provides a method of demounting a work piece. The method includes placing a support structure, which has a work piece affixed to a lower surface thereof, over an opening in a demounting apparatus, creating a pressure differential between an interior of the demounting apparatus and an exterior position near the demounting apparatus, such as by exerting a vacuum through the interior of the demounting apparatus to thereby pull a work piece away from the support structure. 
     These and other features and advantages of the invention will become more apparent from the following detailed description of preferred embodiments of the invention which is provided in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a demounting apparatus constructed in accordance with a first embodiment of the present invention. 
     FIG. 2 is a top view of the demounting apparatus of FIG.  1 . 
     FIG. 3 is a cross-sectional view taken along line III—III of the demounting apparatus of FIG.  1 . 
     FIG. 4 is a cross-sectional view like FIG. 3 showing the force of air pressure acting on and a vacuum being exerted within the demounting apparatus of FIG.  1 . 
     FIG. 5 is a cross-sectional view like FIG. 4 showing release of a work piece. 
     FIG. 6 is a cross-sectional view of a demounting apparatus constructed in accordance with a second embodiment of the present invention. 
     FIG. 7 is a cross-sectional view of a demounting apparatus constructed in accordance with a third embodiment of the present invention. 
     FIG. 8 is a cross-sectional view of the demounting apparatus of FIG. 7 showing an inflated inflation device. 
     FIG. 9 is a cross-sectional view of a demounting apparatus constructed in accordance with a fourth embodiment of the present invention. 
     FIG. 10 is a cross-sectional view of a demounting apparatus constructed in accordance with a fifth embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to the drawings, where like numerals designate like elements, there is shown in FIGS. 1-3 a demounting apparatus  10  including a conduit  11 . The conduit  11  has a general cylindrical conduit wall  12  with a first end  14  and an opposed second end  16 . The conduit wall  12  has an opening  20 , through which a vacuum is pulled in a direction of the arrow B (FIG.  4 ). Although illustrated as being generally cylindrical, the conduit  11  may instead be rectangular or any other suitable tubular configuration. 
     As shown in FIG. 3, a cushion  26  is positioned within the second end  16 . The cushion  26  is formed of an elastic material, such as, for example, an elastomer. 
     A support structure  25  having a work piece  50  adhered thereto is mounted on the conduit  11  over the first end  14 . The support structure  25  comprises a hoop  24  and a tape  22  upon which a work piece  50  is adhered. The work piece  50  may be any element associated with semiconductor fabrication, such as, for example, a wafer or portion thereof, chip, reticule, mask, frame lead, or integrated circuit package. As shown, for example, in FIG. 3, the work piece  50  faces the interior of the conduit  11 . 
     In operation, and with reference to FIGS. 4-5, a vacuum is drawn through the opening  20  in the direction of the arrow B. The vacuum creates a pressure differential between the interior of the conduit  11  and the exterior of the conduit  11 . Particularly, the pressure within the conduit  11  is reduced relative to the pressure outside of the conduit  11 . The resulting pressure differential causes air pressure to push the support structure  25  and the cushion  26  inwardly, as shown by, respectively, arrows A and C. 
     The force from the air pressure in the direction of the arrows A gives the support structure  25  a generally curved profile. Given that the work piece  50  is generally rectangular, the bent tape  22  pulls away from the work piece  50  such that the support structure  25  tends to lose some of its adherence to the flat side of the work piece  50 . This loss of adherence, along with the force of the vacuum being exerted through the conduit  11 , causes the work piece  50  to release from the support structure  25  and land on the cushion  26 . 
     As noted above, the cushion  26  is made of a soft, generally elastic material capable of protecting the work piece  50  upon its release from the support structure  25 . Further, the pressure differential created by the vacuum pulls the cushion  26  inwardly in the direction of the arrows C, giving the cushion  26  a generally curved profile. This curved profile reduces the distance the work piece  50  falls before being caught by the cushion  26 . 
     By utilizing a pressure differential to create a curved profile for a support structure  25  upon which a semiconductor work piece  50  is mounted and a vacuum on the interior of conduit  11 , the work piece  50  is easily released from the tape  22  of the support structure  25 . Further, the work piece  50  is released undamaged. In addition, the use of a cushion  26  to catch the released work piece  50  assists in preventing damage to the work piece  50 . 
     With reference to FIG. 6, another embodiment of the present invention is illustrated. A demounting apparatus  100  is shown having a conduit  11  and an inflatable device  30 . The inflatable device  30 , shown in its inflated state in FIG. 6, encircles the conduit  11  along a longitudinal axis thereof. Specifically, the inflatable device  30 , shown in its inflated state in FIG. 6, is positioned such that it is over the first and second ends  14 ,  16 . When first placed around the conduit  11 , the inflatable device  30  is in a deflated state. Once positioned over the ends  14 ,  16 , the inflatable device  30  is inflated. The device  30  may be inflated with any suitable media, such as, for example, air, any inert gas, or liquid, such as water. 
     Inflation of the device  30  causes the device  30  to both expand and to exert a constricting force on the support structure  25  and the cushion  26 . Specifically, a surface  31  of the device comes in contact with the support structure  25  and the cushion  26 . Further, inflation of the device  30  causes elastic deformation of both the support structure  25  and the cushion  26 . Specifically, the cushion  26  and the support structure  25  are pushed inwardly in the same directions that they are pulled by the embodiment described above utilizing pressure differential, namely in the directions of, respectively, the arrows C and A (FIG.  4 ). As with the previously described embodiment, the curved profile of the support structure  25  creates a loss of adherence between the tape  22  and the work piece  50 . That loss of adherence along with the exertion of a vacuum through the conduit  11  causes the work piece  50  to release from the tape  22  of the support structure  25 , and be caught by the cushion  26 . 
     Although shown with the cushion  26 , it is possible for the inflatable device  30  to be used without the cushion  26 . Specifically, and as shown in FIG. 10, a demounting apparatus  400  has an inflatable device  230  which is sized and shaped when inflated so as to enclose the entire second end  16 . Thus, it may not be necessary to include the cushion  26 , as the device  230  will also act to catch the work piece  50  upon its release from the tape  22  and prevent the work piece  50  from becoming damaged. 
     Although the devices  30 ,  230  are illustrated as completely surrounding the conduit  11 , the invention is not so limited. FIGS. 7-8 illustrate a demounting apparatus  200  having an inflatable device  130 . Specifically, FIG. 7 shows the device  130  in an uninflated state positioned over the support structure  25 , while FIG. 8 shows the device  130  in an inflated state. The cushion  26  is being pressed inwardly (arrows C) by the pressure differential caused by the vacuum (arrow B). When deflated, the device  130  may take the form of a deflated balloon, and when inflated is generally circular, as shown in FIG.  8 . The device  130  may be inflated by any suitable medium. Since the device  130  does not completely encircle the conduit  11 , the constricting force as described with reference to the device  30  is absent, and so the device  130  should be inflated with a heavier medium, such as, for example, a liquid such as water. Although not illustrated, a similar inflatable device  130  may be placed over the second end  16  and used in lieu of the air pressure to force the cushion  26  inwardly. Further, as described above with reference to FIG. 10, the cushion  26  is optional and the device  130  may be sized and shaped to inflate and cover the second end  16 . 
     With reference to FIG. 9, another embodiment of the present invention is shown, specifically, a demounting apparatus  300  including the conduit  11  and a piston  40 . The piston  40  has a rounded end  41 . The piston  40  is movable in a direction generally parallel to the conduit wall  12 . In operation, the piston  40  is moved into contact with the support structure  25 , thereby elastically deforming the support structure  25  and creating a curved profile. A vacuum is exerted in the direction of the arrow B, thereby enhancing the curved profile of the support structure  25  and inwardly pulling the cushion  26 . The curved profile of the support structure  25  and the exertion of the vacuum assist in releasing the work piece  50  from the tape  22 . 
     The present invention, as described above, provides an easy and effective way to release a semiconductor work piece from a highly adherent material without damage to the work piece. The present invention accomplishes this by forcing the adherent material to adopt a curved profile, which reduces the adherent properties on a portion of the work piece, and by exerting a vacuum force on the work piece to pull it from the adherent material. 
     While preferred embodiments of the invention have been described and illustrated, the invention is not limited by the foregoing description as many modifications and substitutions can be made without departing from the spirit and scope of the invention. For example, while some embodiments have been described as using a vacuum to pull the support structure  25  and the cushion  26  inwardly into the conduit  11 , instead air pressure may be directed from an exterior of the conduit  11  at the support structure  25  and the cushion  26  to achieve the same curved profiles. A vacuum could also be used to assist in creating the curved profiles. Further, an air-tight cover may be required over the cylinder to contain the pressure. Accordingly, the scope of the present invention is not to be considered as limited by the specifics of the particular structure which have been described and illustrated, but is only limited by the scope of the appended claims.