Patent Publication Number: US-2011061808-A1

Title: Sheet sticking apparatus and sticking method

Description:
FIELD OF THE INVENTION 
     The present invention relates to a sheet sticking apparatus and a sticking method, and more particularly to a sheet sticking apparatus and a sticking method capable of sticking an adhesive sheet to an adherend under a decompression atmosphere. 
     BACKGROUND OF THE ART 
     Conventionally, semiconductor wafers (hereinafter, simply referred to as “wafers”) are stuck with an adhesive sheet on a circuit surface and a rear surface thereof, and are subjected to various treatments such as rear-face grinding and dicing. 
     Patent Document 1 discloses the above adhesive sheet sticking apparatus. The apparatus is configured to form a space on each of the lower surface side of a rubber sheet for supporting a wafer and the upper surface side of a dicing sheet disposed relatively to the wafer, and, after reducing the pressures in such spaces, open one of the spaces to the atmosphere to stick the sheet to the wafer. 
     [Patent document 1]: Japanese Patent Application Laid-Open No. 2005-26377 
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     However, the sheet sticking apparatus disclosed in the patent document 1 has an arrangement in which it must reduce the pressures in the spaces located on the lower and upper surface sides of the rubber sheets while keeping the pressures in the space on the lower surface side equal to that on the upper surface side. Therefore, there is such a disadvantage that this arrangement makes the pressure control thereof very complicated. 
     Also, the wafer is a full contact type in which the entire area on the lower surface side of the wafer is supported in contact with the rubber sheet. If any foreign object such as dust is deposited between the lower surface of the wafer and the rubber sheet, then damage to the wafer, such as a crack, is caused when a pressure for sticking the dicing sheet is applied. 
     OBJECT OF THE INVENTION 
     The present invention has been proposed in view of the above disadvantages. It is an object of the present invention to provide a sheet sticking apparatus and a sticking method capable of sticking an adhesive sheet to an adherend without any complicated control of decompression. 
     Also, another object of the present invention is to provide a sheet sticking apparatus and a sticking method capable of effectively eliminate a factor in damage which may be caused when a pressure force is applied to the adherend by providing, in a limited manner, a region for supporting the adherend. 
     MEANS FOR SOLVING PROBLEMS 
     In order to achieve the above object, the present invention adopts such an arrangement that a sheet sticking apparatus comprises a table for supporting an adherend, an openable and closeable case for accommodating the table and forming a decompression chamber in the case, and a feeding means for feeding an adhesive sheet to a position where the adhesive sheet faces the adherend, the adhesive sheet being stuck to the adherend by closing the case and performing a predetermined control of the pressure in the decompression chamber; 
     wherein the sheet sticking apparatus further comprising a sandwiching means disposed, in the case, in a position relative to the table, the sandwiching means being sandwiching only an outer periphery portion of the adherend together with the adhesive sheet by interaction with the table in a state where a single decompression chamber is formed by closing the case. 
     In the present invention, the sandwiching means is provided so as to form a space existing before sticking between the adhesive sheet and the adherend, the space being independent from the decompression chamber. 
     Also, the present invention adopts such an arrangement that the table comprises a supporting convex portion for supporting the outer periphery portion of the adherend from below; and the sandwiching means comprises a sandwiching convex portion corresponding to the supporting convex portion and sandwiching the adhesive sheet from top of the adhesive sheet. 
     Further, the present invention may adopt a sheet sticking method using a sheet sticking apparatus including a table for supporting an adherend, an openable and closeable case for accommodating the table and forming a decompression chamber in the case, and a feeding means for feeding an adhesive sheet to a position where the adhesive sheet faces the adherend, the method comprising the steps of: 
     supporting a plate-like member on the table; feeding an adhesive sheet to a position relative to the plate-like member; forming a decompression chamber by closing the case; reducing the pressure in the decompression chamber; sandwiching only an outer periphery portion of the plate-like member together with the adhesive sheet by interaction with the table; and sticking the adhesive sheet to the plate-like member by releasing the reduced pressure in the decompression chamber. 
     Furthermore, in the sheet sticking method, such a method is adopted that the outer periphery portion of the plate-like member is sandwiched together with the adhesive sheet by a supporting convex portion for supporting an outer periphery portion of the adherend from below, and a sandwiching convex portion corresponding to the supporting convex portion and sandwiching the adhesive sheet from top of the adhesive sheet. 
     According to the present invention, only the outer periphery portion of the adherend is sandwiched together with the adhesive sheet by the table and the sandwiching means in a state where the pressure in the decompression chamber is reduced. Therefore, the adhesive sheet is stuck to the adherend by simply controlling the pressure so as to open the decompression chamber to the atmosphere. 
     Thus, a plurality of pressure control valves, pipes, pressure balance control and the like, which are required in the case of providing the plurality of decompression chambers, are not required so that a complicated arrangement, pressure control, or management are not required. 
     Also, only the outer periphery portion is supported by the table, and therefore the adherend can have a decreased contact area between the adherend and the table. Asa result, a foreign object on the table, for example, is not pressed against the adherend, and therefore even when a fragile adherend such as a wafer is supported, the damage to the adherend can be effectively prevented. 
     Further, an independent space existing before sticking is formed between the adherend and the adhesive sheet by the table and the sandwiching means in a state where the pressure in the decompression chamber is reduced. Therefore, by controlling the pressure so as to open the decompression chamber to the atmosphere, the space existing before sticking substantially disappears due to the atmosphere pressure, so that the adhesive sheet is stuck to the adherend. 
     Note that the term “decompress” in the description is herein used as a concept including vacuum. The term “a space existing before sticking” is used to refer to a void which occurs between an adherend and an adhesive sheet in a region in which a force sandwiching the adherend and the adhesive sheet does not act. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross-sectional front view showing a part of a sheet sticking apparatus of the embodiment. 
         FIG. 2  is a schematic plan view showing the apparatus with a part of  FIG. 1  omitted. 
         FIG. 3  is a schematic front view showing a state where a decompression chamber is formed. 
         FIG. 4  is a schematic cross-sectional view showing a state where a sandwiching means sandwiches a wafer together with an adhesive sheet. 
         FIG. 5  is an enlarged cross-sectional view showing a state where a space existing before sticking is formed between the wafer and the adhesive sheet. 
         FIG. 6  is an enlarged cross-sectional view showing a state where the space existing before sticking disappears so that the adhesive sheet is stuck to the wafer. 
         FIG. 7  is a cross-sectional view similar to  FIG. 5  but showing a variation with an adherend having a relatively large thickness in the outer periphery portion thereof. 
         FIG. 8  is a cross-sectional view similar to  FIG. 6  but showing the variation with an adherend having a relatively large thickness in the outer periphery portion thereof. 
     
    
    
     EXPLANATION OF REFERENCE NUMERALS 
     
         
           10 : sheet sticking apparatus 
           11 : table 
           11 A: supporting convex portion 
           14 : case 
           15 : feeding means 
           29 : sandwiching means 
           32 : sandwiching convex portion 
         C: decompression chamber 
         C 4 : space existing before sticking 
         S: adhesive sheet 
         W: semiconductor wafer (adherend) 
       
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. 
       FIG. 1  shows a schematic front view of a sheet sticking apparatus according to the embodiment, and  FIG. 2  shows a schematic plan view of the apparatus with a part of  FIG. 1  omitted. In these figures, a sheet sticking apparatus  10  comprises: a table  11  for supporting a plate-like member, in particular a generally circular wafer W, as an adherend; an openable and closeable case  14  for accommodating the table  11  and forming a decompression chamber C therein; and a feeding means  15  for feeding an adhesive sheet S having pressure-sensitive adhesive properties to a position where the adhesive sheet S faces a adhered surface which is an upper surface of the wafer W, in an opened state of the case  14 . Here, as shown in  FIG. 2 , the adhesive sheet S is adopted, which has a width dimension that does not separate the decompression chamber C into upper and lower portions. The adhesive sheet S forms a clearance C 1  without covering the entire inner circumference area of the case  14  when fed to the position where the adhesive sheet S faces the adhered surface of the wafer W, so that the decompression chamber C is formed as a single space. Note that the clearances C 1  may be a passage such as a pipe and a through-hole to prevent the decompression chamber C from being separated into a plurality of spaces. 
     The table  11  has a larger plane area than the size of the wafer W, and comprises, on an upper surface of the table  11 , an annular supporting convex portion  11 A for supporting the wafer W from below while only contacts an outer periphery portion on the lower surface side of the wafer W. Therefore, in a state where the table  11  supports the wafer W, a space C 2  is formed between the lower surface side of the wafer W except the outer periphery portion thereof and an upper surface  11 B of the table  11 . The table  11  has a communicating hole  11 D formed between an outer peripheral surface  11 C and the upper surface  11 B thereof. The space C 2  communicates with the decompression chamber C to constitute a part of the decompression chamber C. An output shaft  17  of a linear motor  16  is fixed on the lower surface side of the table  11 . The table  11  is disposed such that the table  11  can move upward and downward by driving the linear motor  16 . 
     The case  14  comprises a first case  20  located on the lower part side in  FIG. 1 , and a second case  21  located on the upper part side in  FIG. 1 . The first case  20  comprises a bottom portion  22  for supporting the table  11  through the linear motor  16 , and an erecting portion  24  which forms a generally circular recess portion  23  in a central region thereof. The first case  20  is connected to a pipe  25  and a three-way solenoid valve  26  which are connected to the erecting portion  24 , and is provided so as to be able to move in a vertical direction through an elevating means (not shown). Note that the three-way solenoid valve  26  is connected to a pipe  37 , which is connected to a decompression pump (not shown), and a pipe  38  for introducing the atmosphere. Thus, the three-way solenoid valve  26  can reduce the pressure in the decompression chamber C, and obtain atmospheric pressure by releasing the reduced pressure. 
     The second case  21  includes a top portion  27  and a drooping portion  28 . A sandwiching means  29  is disposed on the lower surface side of the top portion  27 , in a position relative to the table  11 . The sandwiching means  29  includes a sandwiching plate  31  provided such that the sandwiching plate  31  can move upward and downward through a linear motor  30 , and an annular sandwiching convex portion  32  provided on the outer periphery side of a lower surface of the sandwiching plate  31 . The sandwiching convex portion  32  has the substantially same shape as the supporting convex portion  11 A so that the sandwiching convex portion  32  is adapted to press and sandwich only an upper surface side of the outer periphery portion of the wafer W via the adhesive sheet S from top. A plurality of through-holes  31 A are formed within a plane of the sandwiching plate  31 . Even in a state where the sandwiching means  29  sandwiches the adhesive sheet S and the wafer W between the table  11  and the sandwiching means  29 , a space C 3  formed between the adhesive sheet S and the sandwiching plate  31  (see  FIG. 4 ) communicates with the decompression chamber C to constitute a part of the decompression chamber C. Note that a lower end surface of the drooping portion  28  receives an O-ring  33  therein. 
     The second case  21  is supported movably in a vertical direction through a moving means (not shown). The second case  21  forms the decompression chamber C by interaction with the first case  20 , when the second case  21  is lowered on the first case  20  side so that the lower end surface of the drooping portion  28  is pressed against an upper end side of the erecting portion  24 . 
     The feeding means  15  comprises: a support roller  40  having a lock mechanism for supporting a raw sheet R with a strip-shaped release liner RL temporarily stuck to an adhesive agent layer side of a strip-shaped adhesive sheet S; a winding means  41  for collecting the release liner RL; a peel plate  42  for peeling the adhesive sheet S off from the release liner RL; a drawing and winding means  45  for drawing the adhesive sheet S to a position where the adhesive sheet S faces the adhered surface of the wafer W, i.e., the upper surface thereof, and for winding an unnecessary adhesive sheet S 1  positioned on an outer side of the adhesive sheet S stuck to the wafer W; a cutting means (not shown) for cutting the adhesive sheet S stuck to the wafer W in accordance with the size of the wafer W; and a moving means  48  for supporting the drawing and winding means  45  movably in a horizontal direction in  FIG. 1 . Note that the cutting means may use a multi-jointed robot described in Japanese Patent Application No. 2006-115106 which has already filed by the present applicant. 
     The winding means  41  comprises a drive roller  50  rotated by driving of a motor M 1  supported by a frame F 1 , a pinch roller  51  for sandwiching the release liner RL between the drive roller  50  and the pinch roller  51 , and a release liner winding roller  44  for winding the release liner RL by rotating thereof in synchronism with the drive roller  50  by the motor M 1 . 
     The drawing and winding means  45  comprises a drive roller  53  rotated by driving of a motor M 2  supported by a frame F 2 , a pinch roller  54  for sandwiching the unnecessary adhesive sheet S 1  between the drive roller  53  and the pinch roller  54 , and an unnecessary-sheet winding roller  47  for winding the unnecessary adhesive sheet S 1  by rotating thereof in synchronism with the drive roller  53  by the motor M 2 . 
     The moving means  48  comprises a single axis robot  55  extending in a horizontal direction in  FIG. 1 . The frame F 2  is fixed to a slider  56  of the single axis robot  55  so that the drawing and winding means  45  can move in the horizontal direction. 
     A sheet sticking method according to the embodiment will be now described with reference to  FIGS. 3 to 6  as well. 
     First, a lead end of a raw sheet R supported by the support roller  40  is drawn by a predetermined length, in a state where the first and second cases  20 ,  21  are positioned away from each other to open the case  14 . The release liner RL is peeled off from the adhesive sheet Sat a tip location of the peel plate  42 . The release liner RL is fixed to the release liner winding roller  44 . On the other hand, the adhesive sheet S is fixed to the unnecessary-sheet winding roller  47  of the drawing and winding means  45  which is located at a position shown by a two-dot chain line in  FIG. 1 . 
     When the wafer W is transferred by a transfer means (not shown) so as to be supported by the supporting convex portion  11 A only in the lower surface side of the outer periphery portion of the wafer W, the drawing and winding means  45  moves from the position shown by the two-dot chain line in  FIG. 1  to a position illustrated by a solid line in  FIG. 1  in a state of locking the rotation of the drive roller  53 . In synchronism with such movement, the winding means  41  is driven to collect the release liner RL. Thus, the adhesive sheet S passes over the first case  20  and is fed to the position where the adhesive sheet S faces the upper surface of the wafer W. 
     Next, the first case  20  is lifted, and the second case  21  is lowered, so that a single decompression chamber C is formed by the first and second cases  20  and  21  (see  FIG. 3 ). In this state, the pressure in the decompression chamber C is reduced through the pipe  37  by controlling the solenoid valve  26 . 
     Then, when the decompression chamber C reaches to a decompression state, the table  11  is lifted, and the sandwiching plate  31  is lowered, so that the sandwiching convex portion  32  sandwiches only the outer periphery portion of the wafer W together with the adhesive sheet S by interaction with the supporting convex portion  11 A. In this way, it can be prevented to apply a pressing force to an inner surface of the fragile wafer W, thereby preventing an external force from being applied to the surface on which a circuit is formed. Also, such sandwiching causes the formation of a space C 4  existing before sticking (see,  FIGS. 4 and 5 ) which is produced by no sandwiching force applied between the inner area of the wafer W and the adhesive sheet S. In this case, the space C 2  on the lower surface side of the wafer W and the space C 3  on the upper surface side of the adhesive sheet S form the single decompression chamber C in the case  14  by the communicating hole  11 D formed in the table  11  and the through-hole  31 A formed in the sandwiching plate  31 , and in such a state, the space existing before sticking C 4  is isolated from the decompression chamber C, thereby becoming an independent space. 
     In this way, the decompression chamber C is set to atmosphere pressure by controlling the three-way solenoid valve  26  to introduce the atmosphere from the pipe  38  after forming the space existing before sticking C 4 . As shown in  FIG. 6 , due to ventilation to atmosphere, the space existing before sticking C 4  substantially disappears by the atmosphere pressure, so that the adhesive sheet S is stuck to the wafer W. 
     When sticking of the adhesive sheet S is completed, the second case  21  is lifted to open the case  14 . The adhesive sheet S, then, is cut into a closed loop shape along the outer periphery of the wafer W through the cutting means (not shown). 
     After the cutting of the adhesive sheet S, the drive roller  53  and the unnecessary-sheet winding roller  47  move to the position shown by the two-dot chain line in  FIG. 1  while the rollers  53  and  47  rotate in a state where the support roller  40  and the drive roller  50  are locked. Thus, the unnecessary adhesive sheet S 1  resulting from the above cutting is wound. 
     The wafer W stuck with the adhesive sheet S is transported to a subsequent process or a predetermined storage locker through a conveying means (not shown), and a wafer W to be subjected to subsequent sticking is transferred on the table  11 , and thereafter the adhesive sheet S is stuck thereto as well. 
     Therefore, according to the embodiment, the adhesive sheet S can be stuck within the single decompression chamber C without applying a pressing force to the surface inside of the wafer W. The adhesive sheet S can be stuck to the wafer W by forming the space existing before sticking C 4  and controlling the pressure to return the decompression chamber C to atmosphere pressure to cause the space existing before sticking C 4  to disappear. As a result, it is not required to perform complicated pressure control that reduces pressures in a plurality of decompression chambers while maintaining pressures in the decompression chambers at the same pressure, as a conventional manner, thereby greatly simplifying the decompression control in the decompression chamber C. Moreover, the wafer W has an arrangement in which the lower surface of the outer periphery side thereof is supported by the table  11 , and therefore there is no disadvantage that the wafer W is damaged even when a foreign object such as dust is present on the upper surface of the table  11 . Further, the sheet S can be stuck without trapping air bubble even when a concavity and convexity such as a bump is present on the adhered surface side of the wafer W. 
     Although the best configuration, method, and the like for carrying out the invention have been disclosed in the above description, the invention is not limited thereto. 
     Thus, the invention has been particularly illustrated and described mainly in terms of a specific embodiment, but those skilled in the art may make various modifications to the embodiments described above in term of shapes, quantities, and other detailed configurations without deviating from the scope of a technical idea and an object of the invention. 
     Accordingly, the description limiting the shapes and the like disclosed above is described as an example in order to facilitate understanding of the invention, and is not intended to limit the invention. Therefore, the descriptions of parts name without part or all of the limiting of the shapes and the like thereof are within the invention. 
     In the above embodiment, for example, the pressure sensitive adhesive sheet is used as the adhesive sheet S, but the present invention is not limited thereto, and may adopt a heat-sensitive adhesive sheet for die bonding and the like. In this instance, a heater may be built into the table  11 , and air supplied through the pipe  25  may be hot air. Moreover, the adhesive sheet S may also be fed using an adhesive sheet of sheet-fed type. 
     Further, the adherend is not limited to the wafer W, but may also cover plate-like members such as glass plates, steel plates, or resin plates. The semiconductor wafer may also be a silicon wafer or a compound wafer. Furthermore, the wafer W or the plate-like member is not limited to one having a uniform thickness. For example, as shown in  FIGS. 7 and 8 , the present invention may also apply to adherends of the type with a relatively large thickness in the outer periphery portion thereof.