Patent Publication Number: US-2009226286-A1

Title: Wafer lift-out apparatus and semiconductor apparatus manufacturing method

Description:
The entire disclosure of Japanese Patent Application No: 2008-056158, filed Mar. 6, 2008 is expressly incorporated by reference herein. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a wafer lift-out apparatus and a semiconductor apparatus manufacturing method that are allowed to reliably separate a semiconductor wafer from a spacer when lifting out the semiconductor wafer housed in a container. 
     2. Related Art 
     In recent years, the outer diameters of semiconductor wafers used when manufacturing semiconductor apparatuses have been increased. Also, with the slimming-down of the packages of semiconductor apparatuses, the thicknesses of semiconductor wafers used when manufacturing semiconductor chips have been reduced. In order to convey such slimmed-down semiconductor wafers of larger diameter, a Tupperware (registered trademark), a container made of polyethylene, is used. 
     A Tupperware (registered trademark) is composed of a circumferential wall and a bottom plate that are integrally formed, and a lid. The circumferential wall having an inner diameter that accommodates the outer diameter of a semiconductor wafer leaving a little room is disposed upright on a bottom plate in a cylindrical shape divided at multiple locations. A cushion material is laid on a bottom portion inside the circumferential wall. The predetermined number of semiconductor wafers and spacers (e.g., interlayer paper sheets) are housed in such a manner that the semiconductor wafers and spacers are alternately stacked on the cushion material. The lid is set to cover the circumferential wall. Therefore, even slimmed-down semiconductor wafers of larger diameter are conveyed without causing a problem, by stacking the semiconductor wafers with the spacers therebetween in the container. 
       FIGS. 6 and 7  are drawings schematically showing a method for lifting out a semiconductor wafer  16  from a Tupperware (registered trademark) serving as a container  102   a  using a wafer lift-out apparatus. 
     First, as shown in  FIG. 6 , a wafer suction mechanism  104  mounted on a carrying arm  103  is carried to above the container  102   a  and then the wafer suction mechanism  104  is lowered into the container  102   a  by the carrying arm  103 . Semiconductor wafer  16  and  17  and an interlayer paper sheet  18  are housed in the container  102   a  in an alternately stacked manner. 
     Next, as shown  FIG. 7 , the wafer suction mechanism  104  vacuum-sucks the semiconductor wafer  16  and then the carrying arm  103  lifts up the wafer suction mechanism  104  sucking the semiconductor wafer  16 . At that time, ionizers  115   a  and  115   b  send an ion blow  22  into the container from both sides of the container  102   a . Thus, the interlayer paper sheet  18  and semiconductor wafer  16  are separated so that the interlayer paper sheet  18  is prevented from adhering to the semiconductor wafer  16  sucked by the wafer suction mechanism  104  (see JP-A-2002-246433 (paragraphs 0040 to 0045, FIGS. 2 to 4)). 
     Subsequently, the semiconductor wafer  16  lifted out from the container  102   a  is attached to a dicing tape. 
     However, as for the above-mentioned related-art wafer lift-out apparatus, even if an ion blow is sent onto the side surfaces of the semiconductor wafer  16  and interlayer paper sheet  18  serving as a spacer, the blow may not pass through between the semiconductor wafer  16  and spacer if the semiconductor wafer  16  and spacer adhere to each other by static electricity. In this case, the semiconductor wafer  16  may not be separated from the spacer. That is, the interlayer paper sheet disadvantageously remains adhering to the semiconductor wafer sucked by the wafer suction mechanism  104 . 
     SUMMARY 
     An advantage of the invention is to provide a wafer lift-out apparatus and a semiconductor apparatus manufacturing method that are allowed to reliably separate a semiconductor wafer from a spacer when lifting out the semiconductor wafer housed in a container. 
     According to a first aspect of the invention, a wafer lift-out apparatus for lifting out, from a container in which a plurality of semiconductor wafers and a spacer are housed in such a manner that the semiconductor wafers and the spacer are alternately stacked and that a part of the spacer is exposed from between the semiconductor wafers, one of the semiconductor wafers includes: a wafer suction mechanism for sucking the semiconductor wafers; a carrying mechanism for carrying the wafer suction mechanism; and a spacer retaining mechanism for retaining the part of the spacer. The spacer retaining mechanism retains the part of the spacer when the carrier lifts up the wafer suction mechanism while the wafer suction mechanism sucks one of the semiconductor wafers housed in the container. 
     By adopting the wafer lift-out apparatus according to the first aspect of the invention, one of the semiconductor wafers is reliably separated from the spacer by mechanically retaining the spacer that should be separated. 
     In the wafer lift-out apparatus according to the first aspect of the invention, the spacer retaining mechanism preferably includes: an elastic body mounted on the carrying mechanism; and a retaining unit mounted at a tip of the elastic body. 
     In the wafer lift-out apparatus according to the first aspect of the invention, the elastic body is preferably one of a spring and rubber. 
     In the wafer lift-out apparatus according to the first aspect of the invention, the spacer retaining mechanism preferably includes: an air cylinder; and a retaining unit mounted on the air cylinder. 
     In the wafer lift-out apparatus according to the first aspect of the invention, the spacer retaining mechanism preferably jets compressed air. 
     According to a second aspect of the invention, a semiconductor apparatus manufacturing method includes lifting out, from a container in which a plurality of semiconductor wafers and a spacer are housed in such a manner that the semiconductor wafers and the spacer are alternately stacked and that a part of the spacer is exposed from between the semiconductor wafers, one of the semiconductor wafers. When a wafer suction mechanism is lifted up while the wafer suction mechanism sucks one of the semiconductor wafers housed in the container, the one of the semiconductor wafers is separated from the spacer by retaining the part of the spacer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like reference numerals designate like elements. 
         FIG. 1  is a plan view schematically showing an overall structure of a mount apparatus including a wafer lift-out apparatus according to an embodiment of the invention. 
         FIG. 2  is a drawing schematically showing a method for lifting out a wafer using the wafer lift-out apparatus shown in  FIG. 1 . 
         FIG. 3  is a drawing schematically showing a method for lifting out a wafer using the wafer lift-out apparatus shown in  FIG. 1 . 
         FIG. 4  is a drawing schematically showing a method for lifting out a wafer using the wafer lift-out apparatus shown in  FIG. 1 . 
         FIG. 5  is a drawing schematically showing a method for lifting out a wafer using the wafer lift-out apparatus shown in  FIG. 1 . 
         FIG. 6  is a drawing schematically showing a method for lifting out a wafer from a Tupperware (registered trademark) serving as a container using a wafer lift-out apparatus. 
         FIG. 7  is a drawing schematically showing the method for lifting out a wafer from a Tupperware (registered trademark) serving as a container using a wafer lift-out apparatus. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Now, embodiments of the invention will be described with reference to the accompanying drawings. 
       FIG. 1  is a plan view schematically showing an overall structure of a mount apparatus including a wafer lift-out apparatus according to an embodiment of the invention. 
     The mount apparatus shown in  FIG. 1  automatically performs a mount process of automatically lifting out a slimmed-down semiconductor wafer of larger diameter from a container made of polyethylene and aligning the semiconductor wafer, then attaching the semiconductor wafer to an adhesive tape attached to a ring frame, placing the ring frame onto a reverse placement unit, and then housing the ring frame in a cassette of a cassette case. A wafer mount line is linearly set in an upper part of  FIG. 1  on a base  1 . Disposed below the wafer mount line are a carrying arm  3  of the wafer lift-out apparatus for lifting out a wafer from a container  2  and an alignment apparatus. 
     The above-mentioned wafer mount line is formed by linearly disposing a ring frame supply unit  10 , a tape attachment unit  11 , a wafer mount unit  12 , and the reverse placement unit  13 . A semiconductor wafer placed on the reverse placement unit  13  is housed in a cassette (not shown) of a cassette case  14 . The ring frame supply unit  10  supports multiple ring frames (not shown) on a lifting table thereof. Each time a ring frame is taken out, the lifting table intermittently ascends by the thickness of the ring frame. The tape attachment unit  11  attaches an adhesive tape (not shown) to the upper surface of a ring frame taken out from the ring frame supply unit  10  with the adhesive surface of the adhesive tape directed downward and cuts the attached adhesive tape along the perimeter of the ring frame. The wafer mount unit  12  overlays is a tape-attached ring frame provided by the tape attachment unit  11  on a semiconductor wafer sucked and held on a suction table, and attaches the semiconductor wafer to the adhesive tape of the ring frame in a vacuum chamber by applying pressure. The reverse placement unit  13  receives the semiconductor wafer-attached ring frame from the wafer mount unit  12  in such a manner that the ring frame is reversed. 
     In the wafer mount unit  12 , a semiconductor wafer is provided onto the suction table in such a manner that a circuit pattern of the semiconductor wafer is directed downward and the back surface thereof is directed upward, and an adhesive tape is attached to the back surface. In the reverse placement unit  13 , a circuit pattern of a semiconductor wafer is directed upward. 
     In some cases, a protection tape is attached to the entire circuit pattern surface of a semiconductor wafer and the protection tape is stripped off before a dicing process. 
     The container  2  in which semiconductor wafers and an interlayer paper sheet serving as a spacer are housed in an alternately stacked manner includes a placement unit. A wafer alignment unit and the wafer mount unit  12  are aligned in an X axis direction perpendicular to the wafer mount line. The carrying arm  3  of the semiconductor wafer suction/lift-out apparatus is configured so that the carrying arm is freely moved in the vertical direction as well as X axis direction by a vertical movement mechanism  5   a  and an X axis direction movement mechanism  5   b . The wafer lift-out apparatus is a mechanism that successively lifts out a semiconductor wafer from the container  2  and carries the lifted-out semiconductor wafer from the wafer alignment unit to the wafer mount unit  12 . A spacer suction/carrier  8  is configured so that it is freely moved in a vertical direction as well as a Y axis direction parallel with the wafer mount line by a carrying arm  7 . A spacer lift-out mechanism  6  includes a carrier  8  and a spacer housing box  9  for housing a spacer lifted out from the container  2 . 
     Next, the wafer lift-out apparatus will be described in detail with reference to  FIGS. 2 to 5 .  FIGS. 2 to 5  are drawings schematically showing a method for lifting out a wafer using the wafer lift-out apparatus shown in  FIG. 1 . 
     As shown in  FIGS. 2 to 5 , the wafer lift-out apparatus includes the carrying arm  3 , a wafer suction mechanism  4  mounted on the carrying arm  3 , a spacer retaining mechanism  21  mounted on the carrying arm  3 , and ionizers  15   a  and  15   b  disposed on both sides of the container  2 . 
     The carrying arm  3  is vertically freely moved by the vertical movement mechanism  5   a  shown in  FIG. 1 . The wafer suction mechanism  4  sucks the semiconductor wafers  16  and  17  by vacuum suction. The spacer retaining mechanism  21  has a retaining unit  20  at its tip. The retaining unit  20  is coupled to the carrying arm  3  with a spring  19  therebetween. The ionizers  15   a  and  15   b  send an ion blow  22  from both sides of the container  2  into the container  2 . 
     Next, the method for lifting out a semiconductor wafer using the wafer lift-out apparatus will be described. 
     First, as shown in  FIG. 2 , the carrying arm  3  carries the wafer suction mechanism  4  to above the container  2  and then lowers it into the container  2 . Here, it is assumed that the semiconductor wafers  16  and  17  and interlayer paper sheet  18  are housed in the container  2  in an alternately stacked manner and that the interlayer paper sheet  18  is formed in a larger size than that of the semiconductor wafers  16  and  17  and therefore a part of the interlayer paper sheet  18  is exposed from between the stacked semiconductor wafers  16  and  17 . 
     When the carrying arm  3  is lowered as described above, the retaining unit  20  of the spacer retaining mechanism  21  makes contact with the exposed part of the interlayer paper sheet  18  and, at the same time, the spring  19  shrinks. Subsequently, the wafer suction mechanism  4  makes contact with the semiconductor wafer  16  and vacuum-sucks it. This state is shown in  FIG. 3 . 
     Next, as shown in  FIG. 4 , the carrying arm  3  is lifted up together with the semiconductor wafer  16  sucked by the wafer suction mechanism  4 . At that time, the ionizers  15   a  and  15   b  send the ion blow  22  from both sides of the container  2 . In this case, a gap is forcefully made between the semiconductor wafer  16  and interlayer paper sheet  18  since the part of the interlayer paper sheet  18  retained by the retaining unit  20  is kept retained by the force of the spring  19  even if the wafer suction mechanism  4  is lifted up. Since the ion blow  22  is sent into the gap, the ion blow  22  reliably passes through the gap. As a result, the semiconductor wafer  16  is reliably separated from the interlayer paper sheet  18 . 
     Subsequently, as shown in  FIG. 5 , the carrying arm  3  is further lifted up so that the semiconductor wafer  16  is lifted out from the container  2 . Subsequently, a process of attaching the lifted-out semiconductor wafer  16  to a dicing tape is performed. 
     The related art is unreliable in separating a semiconductor wafer from an interlayer paper sheet because a semiconductor wafer may not be separated from an interlayer paper by an ion blow depending on the adhesiveness between the semiconductor wafer and interlayer paper. On the other hand, in this embodiment, the interlayer paper sheet  18  that should be separated is retained mechanically so that an ion blow reliably passes through. Thus, the semiconductor wafer  16  and interlayer paper sheet  18  are reliably separated. 
     A semiconductor apparatus manufacturing method according to another embodiment of the invention includes the process shown in  FIGS. 2 to 5 . That is, this semiconductor apparatus manufacturing method includes the process of lifting out the semiconductor wafer  16  from the container  2  in which the semiconductor wafers  16  and  17  and interlayer paper sheet  18  serving as a spacer are housed in an alternately stacked manner and from which a part of the interlayer paper sheet  18  is exposed. In the process, the semiconductor wafer  16  is separated from the interlayer paper sheet  18  by retaining the part of the interlayer paper sheet  18  when the wafer suction mechanism  4  is lifted up while the wafer suction mechanism  4  sucks the semiconductor wafer  16  housed in the container  2 . 
     The invention is not limited to the above-mentioned embodiments and various changes can be made to the embodiments. For example, in the above-mentioned embodiments, the spacer retaining mechanism  21  has the retaining unit  20  at its tip and the retaining unit  20  is coupled to the carrying arm  3  with the spring  19  therebetween, but not limited thereto. Another type of spacer retaining mechanism may be used as long as the spacer retaining mechanism retains the part of the interlayer paper sheet  18  when the wafer suction mechanism  4  is lifted up by a carrying mechanism while the wafer suction mechanism  4  sucks the semiconductor wafer  16  housed in the container  2 . For example, the following spacer retaining mechanisms may be used. 
     For example, a spacer retaining mechanism using another elastic body (e.g., rubber) instead of the spring  19  may be used. Also, the wafer suction mechanism  4  and spacer retaining mechanism  21  do not always need to be coupled to each other via the carrying arm  3  therebetween. For example, a spacer retaining mechanism that includes an air cylinder, which is independent of the wafer suction mechanism  4 , and the retaining unit  20  mounted to the air cylinder and retains a part of the spacer  18  by moving the retaining unit  20  using the air cylinder may be used. Also, a spacer retaining mechanism that retains the part of the spacer  18  using a mechanism that jets compressed air may be used. 
     While the interlayer paper sheet  18  is used as a spacer in the above-mentioned embodiments, a material (e.g., a resin, plastic, chemical fibers, or a mixture thereof) other than paper may be used as long as the material is a thin sheet. 
     While an example where the retaining unit  20  of the spacer retaining mechanism retains one location of the spacer is used in the above-mentioned embodiments, a spacer retaining mechanism that is provided with multiple retaining units  20  so as to retain multiple locations of the spacer may be used.