JP6594243B2 - Wafer processing method - Google Patents

Description

  The present invention relates to a method for processing a wafer provided with bumps (electrode bumps) functioning as electrodes (terminals) of a device on the surface side.

  2. Description of the Related Art In recent years, WL-CSP (Wafer Level Chip Size Package) that performs packaging in a wafer state has attracted attention. In this WL-CSP, a plurality of devices formed on the front surface side of a wafer are sealed with a mold resin, and then the wafer is divided into a plurality of package devices corresponding to each device along a planned dividing line (street). To do.

  By the way, when a wafer whose surface side is coated with a mold resin is divided, the cut surface of the wafer is exposed on the side surface of the formed package device. Therefore, a groove is formed along the planned dividing line of the wafer, the mold resin for covering the surface side is filled in the groove, and then the wafer is divided along the groove, so that the periphery of the package device is obtained. A technique that does not expose a wafer has been proposed (see, for example, Patent Document 1).

JP 2006-1000053 A

  However, in the wafer as described above with the surface side coated with the mold resin, the position and orientation of the groove cannot be specified based on the characteristic pattern in the device. Although it is conceivable to specify the position and orientation of the groove based on the bump (electrode bump) exposed from the mold resin, this method has variations in the position and shape of the bump. Could not be identified with high accuracy.

  The present invention has been made in view of such problems, and the object of the present invention is to specify the position of the groove with high accuracy even when the surface of the wafer on which the groove is formed is coated with a mold resin. And providing a wafer processing method that can be processed appropriately.

  According to one aspect of the present invention, a device region in which a device having electrode bumps is formed in a plurality of regions partitioned by a grid-like division-scheduled line, and an outer peripheral surplus region surrounding the device region are provided on the surface side. A wafer processing method comprising: a first groove forming step of forming a first groove having a depth equal to or greater than a finished thickness of the wafer along the division line from the front surface side of the wafer; Molding step for forming a package wafer in which the electrode bump is exposed from the mold resin layer by filling the groove with mold resin and coating the surface side of the wafer with the mold resin, and imaging the electrode bump of the package wafer, After estimating the position where the first groove is formed based on the electrode bump, based on the estimated position of the first groove By forming a second groove having a depth from the mold resin layer side to the first groove in the outer peripheral surplus region, the boundary between the mold resin layer filled in the first groove and the wafer is A second groove forming step that is exposed through the second groove, and a first groove specifying step that specifies a position of the first groove based on the boundary exposed through the second groove; A processing step of processing the package wafer from the mold resin layer side along the identified first groove.

  In one embodiment of the present invention, the second groove is preferably formed with a width wider than the width of the first groove.

  In the wafer processing method according to one aspect of the present invention, after the surface side of the wafer on which the first groove is formed is coated with a mold resin, the second groove having a depth reaching the first groove is formed on the outer periphery. Since the boundary between the mold resin layer formed in the region and filled in the first groove and the wafer is exposed through the second groove, the position of the first groove is accurately determined based on the exposed boundary. Can be specified.

  That is, according to the wafer processing method according to one aspect of the present invention, even when the surface side of the wafer on which the groove is formed is coated with the mold resin, the position of the groove is specified with high accuracy and processed appropriately. it can.

FIG. 1A is a perspective view schematically showing a configuration example of a wafer, and FIG. 1B is an enlarged view of a device portion of the wafer. It is a perspective view which shows typically the structural example of a cutting device. FIG. 3A, FIG. 3B, and FIG. 3C are partial cross-sectional side views for explaining the first groove forming step. FIGS. 4A and 4B are cross-sectional views for explaining the first groove forming step. It is a perspective view which shows typically the wafer after a 1st groove | channel formation step. 6A and 6B are side views for explaining the resin layer forming step during the molding step, and FIG. 6C is a cross-sectional view for explaining the resin layer forming step. is there. It is a perspective view which shows typically the wafer after the resin layer formation step. FIG. 8A is a side view for explaining the resin layer thinning step during the molding step, and FIG. 8B is a cross-sectional view for explaining the resin layer thinning step. It is a perspective view which shows the completed package wafer typically. FIG. 10A is a side view for explaining the wafer thinning step, and FIG. 10B is a cross-sectional view for explaining the wafer thinning step. FIG. 11A is a partial cross-sectional side view for explaining a state in which the position of the first groove is estimated in the second groove forming step, and FIG. It is a top view for demonstrating a mode that a position is estimated. FIG. 12A is a partial cross-sectional side view for explaining a state in which the second groove is formed in the second groove forming step, and FIG. 12B is a diagram in which the second groove is formed. It is a top view for demonstrating a mode. It is a partial cross section side view for demonstrating a 1st groove | channel specific step. FIG. 14A and FIG. 14B are side views for explaining the processing steps. FIGS. 15A and 15B are cross-sectional views for explaining the processing steps, and FIG. 15C is a perspective view schematically showing a completed package device. FIG. 16A is a perspective view for explaining the second groove forming step according to the modified example, and FIG. 16B is a plan view for explaining the second groove forming step according to the modified example. FIG. It is a perspective view which shows typically the structural example of a laser processing apparatus.

  Embodiments according to one aspect of the present invention will be described with reference to the accompanying drawings. The wafer processing method according to the present embodiment includes a first groove forming step (FIGS. 3A, 3B, 3C, 4A, 4B, and 5). (See FIG. 6A), FIG. 6 (B), FIG. 6 (C), FIG. 7, FIG. 8 (A), FIG. 8 (B) and FIG. 9), wafer thinning step (see FIG. 6). 10 (A) and FIG. 10 (B)), the second groove forming step (see FIG. 11 (A), FIG. 11 (B), FIG. 12 (A) and FIG. 12 (B)), the first groove It includes a specific step (see FIG. 13) and a processing step (see FIGS. 14 (A), 14 (B), 15 (A), 15 (B) and 15 (C)).

  In the first groove forming step, a first groove having a depth equal to or greater than the finished thickness of the wafer is formed along the planned dividing line from the front surface side of the wafer. In the molding step, the first groove is filled with a mold resin, and the surface side of the wafer is covered with the mold resin to form a package wafer in which bumps (electrode bumps) are exposed from the mold resin layer.

  In the wafer thinning step, the wafer in the package wafer is thinned from the back side. In the second groove forming step, a position where the first groove is formed is estimated based on the bump, and a second depth reaching the first groove is determined based on the estimated position of the first groove. A groove is formed on the mold resin layer side. Thereby, the boundary between the mold resin layer filled in the first groove and the wafer can be exposed.

  In the first groove specifying step, the position of the first groove is specified based on the boundary exposed through the second groove. In the processing step, the package wafer is processed from the mold resin layer side along the identified first groove. Hereinafter, the wafer processing method according to the present embodiment will be described in detail.

  In the wafer processing method according to the present embodiment, first, a first groove forming step for forming a first groove on the wafer is performed. FIG. 1A is a perspective view schematically showing a configuration example of a wafer used in the present embodiment, and FIG. 1B is an enlarged view of an enlarged device portion of the wafer.

  As shown in FIG. 1A, a wafer 11 used in the present embodiment is formed in a disk shape from a semiconductor material such as silicon, and the surface 11a side includes a central device region and a device. It is divided into an outer peripheral surplus area surrounding the area. The device area is further divided into a plurality of areas by division lines (streets) 13 arranged in a lattice pattern, and a device 15 including an integrated circuit such as an IC or LSI is formed in each area.

  As shown in FIG. 1B, a plurality of bumps (electrode bumps) 17 functioning as electrodes are arranged on the surface 11a side of each device 15. The bumps 17 are made of a metal material such as solder, for example. In the present embodiment, the disk-shaped wafer 11 made of a semiconductor material such as silicon is illustrated, but the material, shape, and the like of the wafer 11 are not limited. For example, a substrate made of a material such as ceramics, metal, or resin can be used as the wafer 11. Similarly, there is no restriction on the type of the device 15.

  Before performing the first groove forming step, for example, a dicing tape 31 (see FIG. 3A) having a diameter larger than that of the wafer 11 is attached to the back surface 11b side of the wafer 11. Further, an annular frame (not shown) made of a material such as stainless steel or aluminum is fixed to the outer peripheral portion of the dicing tape 31. Thereby, the wafer 11 is supported by the annular frame via the dicing tape 31.

  FIG. 2 is a perspective view schematically showing a configuration example of a cutting apparatus in which the first groove forming step and the like are performed. As shown in FIG. 2, the cutting device (processing device) 2 includes a base 4 that supports each structure. On the upper surface of the base 4, a rectangular opening 4 a that is long in the X-axis direction (front-rear direction, processing feed direction) is formed.

  In this opening 4a, an X-axis moving table 6, an X-axis moving mechanism (processing feed mechanism) (not shown) for moving the X-axis moving table 6 in the X-axis direction, and a dustproof and splashproof cover that covers the X-axis moving mechanism 8 is provided. The X-axis movement mechanism includes a pair of X-axis guide rails (not shown) parallel to the X-axis direction, and an X-axis movement table 6 is slidably attached to the X-axis guide rails.

  A nut portion (not shown) is provided on the lower surface side of the X-axis moving table 6, and an X-axis ball screw (not shown) parallel to the X-axis guide rail is screwed to the nut portion. An X-axis pulse motor (not shown) is connected to one end of the X-axis ball screw. By rotating the X-axis ball screw with the X-axis pulse motor, the X-axis moving table 6 moves in the X-axis direction along the X-axis guide rail.

  A holding table (chuck table) 10 for sucking and holding the wafer 11 is provided on the X-axis moving table 6. The holding table 10 is connected to a rotation drive source (not shown) such as a motor, and rotates around a rotation axis substantially parallel to the Z-axis direction (vertical direction). The holding table 10 is processed and fed in the X-axis direction by the X-axis moving mechanism described above.

  The surface (upper surface) of the holding table 10 is a holding surface 10 a that sucks and holds the wafer 11. The holding surface 10 a is connected to a suction source (not shown) through a flow path (not shown) formed inside the holding table 10. Around the holding table 10, a clamp 12 for fixing an annular frame that supports the wafer 11 is provided.

  A transfer unit (not shown) for transferring the wafer 11 described above to the holding table 10 is provided at a position close to the opening 4a. For example, the wafer 11 transported by the transport unit is placed on the holding surface 10a of the holding table 10 in such a manner that the surface 11a side is exposed upward.

  On the upper surface of the base 4, a gate-type support structure 16 that supports a cutting unit (processing unit) 14 for cutting the wafer 11 is disposed so as to straddle the opening 4 a. A cutting unit moving mechanism (index feed mechanism) 18 that moves the cutting unit 14 in the Y-axis direction (index feed direction) and the Z-axis direction is provided on the upper front surface of the support structure 16.

  The cutting unit moving mechanism 18 includes a pair of Y-axis guide rails 20 arranged on the front surface of the support structure 16 and parallel to the Y-axis direction. A Y-axis moving plate 22 constituting the cutting unit moving mechanism 18 is slidably attached to the Y-axis guide rail 20. A nut portion (not shown) is provided on the back surface side (rear surface side) of the Y-axis moving plate 22, and a Y-axis ball screw 24 parallel to the Y-axis guide rail 20 is screwed to the nut portion. Yes.

  A Y-axis pulse motor (not shown) is connected to one end of the Y-axis ball screw 24. If the Y-axis ball screw 24 is rotated by the Y-axis pulse motor, the Y-axis moving plate 22 moves in the Y-axis direction along the Y-axis guide rail 20. A pair of Z-axis guide rails 26 parallel to the Z-axis direction are provided on the surface (front surface) of the Y-axis moving plate 20. A Z-axis moving plate 28 is slidably attached to the Z-axis guide rail 26.

  A nut portion (not shown) is provided on the back surface side (rear surface side) of the Z-axis moving plate 28, and a Z-axis ball screw 30 parallel to the Z-axis guide rail 26 is screwed into the nut portion. Yes. A Z-axis pulse motor 32 is connected to one end of the Z-axis ball screw 30. When the Z-axis ball screw 30 is rotated by the Z-axis pulse motor 32, the Z-axis moving plate 28 moves in the Z-axis direction along the Z-axis guide rail 26.

  A cutting unit 14 for cutting the wafer 11 is provided below the Z-axis moving plate 28. A camera (imaging unit) 34 for imaging the front surface 11 a side of the wafer 11 is installed at a position adjacent to the cutting unit 14. If the cutting unit moving mechanism 18 moves the Y-axis moving plate 22 in the Y-axis direction, the cutting unit 14 and the camera 34 are indexed, and if the Z-axis moving plate 28 is moved in the Z-axis direction, the cutting unit is moved. 14 and the camera 34 move up and down.

  The cutting unit 14 includes an annular cutting blade 36 attached to one end side of a spindle (not shown) that constitutes a rotation axis parallel to the Y-axis direction. A rotation drive source (not shown) such as a motor is connected to the other end side of the spindle, and rotates the cutting blade 36 attached to the spindle.

  Components such as the X-axis moving mechanism, the holding table 10, the transport unit, the cutting unit 14, and the cutting unit moving mechanism 18 are each connected to a control unit (not shown). This control unit controls each component described above according to the processing conditions of the wafer 11 and the like.

  FIGS. 3A, 3B, and 3C are partial cross-sectional side views for explaining the first groove forming step, and FIGS. 4A and 4B are views. FIG. 5 is a cross-sectional view for explaining a first groove forming step. 3A, 3B, and 3C show a cross section (cross section along the planned division line 13) parallel to the planned division line 13 in which the groove is formed. 4A and 4B show a cross section perpendicular to the division line 13 in which the groove is formed.

  In the first groove forming step, first, the back surface 11b side (dicing tape 31) of the wafer 11 is brought into contact with the holding surface 10a of the holding table 10 to apply a negative pressure of the suction source. Further, the annular frame is fixed by the clamp 12. As a result, the wafer 11 is held on the holding table 10 with the surface 11a side exposed upward.

  Next, the holding table 10 and the cutting unit 14 are relatively moved and rotated, and the cutting blade 36 is set above the extension line of the target division line 13. Further, as shown in FIG. 3A, the cutting blade 36 is lowered to a height at which it is cut into the wafer 11. Here, the cutting blade 36 is lowered until the lower end of the cutting blade 36 reaches a position at a depth greater than the finished thickness of the wafer 11 (for example, the thickness after the wafer thinning step described later) from the surface 11a. .

  In this state, as shown in FIGS. 3B and 4A, the holding table 10 is moved (processed) in a direction parallel to the target division line 13 while rotating the cutting blade 36. Feed). As a result, the cutting blade 36 is cut along the target division line 13, and as shown in FIGS. 3C and 4B, the first groove 11 c having a depth greater than the finished thickness is formed. Can be formed.

  After the above procedure is repeated and, for example, the first grooves 11c are formed along all the division lines 13 extending in the first direction, the holding table 10 and the cutting unit 14 are relatively moved and rotated. Thus, the first groove 11c is formed in the same procedure along the division line 13 extending in the second direction different from the first direction. When the first groove 11c is formed along all the division lines 13, the first groove forming step ends.

  FIG. 5 is a perspective view schematically showing the wafer 11 after the first groove forming step. After the first groove forming step, for example, the dicing tape 31 is peeled off from the wafer 11 and removed. In the present embodiment, the first groove 11c is formed by a method in which the cutting blade 36 is cut into the wafer 11. However, the method for forming the first groove 11c is not limited. For example, the first groove 11c can be formed by a method such as ablation processing in which a laser beam having a wavelength that is easily absorbed by the wafer 11 is irradiated.

  After the first groove forming step, the first groove 11c is filled with a mold resin, and the surface 11a side of the wafer 11 is covered with the mold resin so that the bumps 17 are exposed from the mold resin layer. Implement the molding step to form. This molding step includes, for example, a resin layer forming step for forming a mold resin layer on the surface 11a side of the wafer 11 and a resin layer thinning step for exposing the bumps 17 from the mold resin layer.

  6A and 6B are side views for explaining the resin layer forming step during the molding step, and FIG. 6C is a cross-sectional view for explaining the resin layer forming step. is there. The resin layer forming step is performed using, for example, a spin coater 42 shown in FIGS. 6 (A) and 6 (B).

  The spin coater 42 includes a holding table (spinner table) 44 for holding the wafer 11. The holding table 44 is connected to a rotation drive source (not shown) including a motor and the like, and rotates around a rotation axis substantially parallel to the vertical direction. The upper surface of the holding table 44 is a holding surface 44 a that sucks and holds the back surface 11 b side of the wafer 11.

  The holding surface 44 a is connected to a suction source (not shown) through a suction path (not shown) formed inside the holding table 44. By causing the negative pressure of the suction source to act on the holding surface 44a, the wafer 11 is sucked and held by the holding table 44. Above the holding table 44, a nozzle 46 for ejecting the liquid mold resin 21 is disposed.

  In the resin layer forming step, first, the back surface 11b side of the wafer 11 is brought into contact with the holding surface 44a of the holding table 44, and the negative pressure of the suction source is applied. As a result, the wafer 11 is held by the holding table 44 with the surface 11a side exposed upward. In this resin layer forming step, a protective member may be attached to the back surface 11 b side of the wafer 11.

  Subsequently, as shown in FIG. 6A, the liquid mold resin 21 is dropped from the nozzle 46, and the holding table 44 is rotated as shown in FIG. 6B. As the mold resin 21, for example, an epoxy-based thermosetting resin can be used. However, there are no restrictions on the type, material, etc. of the mold resin 21. Thereby, a mold resin layer 23 made of the liquid mold resin 21 is formed on the surface 11 a of the wafer 11.

  In the present embodiment, since the first groove 11c is formed on the surface 11a side of the wafer 11, the mold resin 21 is also filled in the first groove 11c as shown in FIG. 6C. The That is, a part (filling part) 23a of the mold resin layer 23 (mold resin 21) is filled in the first groove 11c, and another part (covering part) of the mold resin layer 23 (mold resin 21). 23b covers the surface 11a side of the wafer 11.

  Then, if the mold resin layer 23 is hardened by a method such as heating, the resin layer forming step is completed. FIG. 7 is a perspective view schematically showing the wafer 11 after the resin layer forming step. As shown in FIG. 7, at the stage where the resin layer forming step is completed, the entire bump 17 is covered with the mold resin layer 23.

  In this embodiment, the mold resin layer 23 is formed by the method using the spin coater 42, but the mold resin layer 23 may be formed by other methods. For example, the mold resin layer 23 may be formed by a method in which a mold is placed on the surface 11a side of the wafer 11 and the mold resin 21 is filled in the gap between the surface 11a of the wafer 11 and the mold.

  After the resin layer forming step, a resin layer thinning step for thinning the mold resin layer 23 and exposing the bumps 17 is performed. FIG. 8A is a side view for explaining the resin layer thinning step, and FIG. 8B is a cross-sectional view for explaining the resin layer thinning step. The resin layer thinning step is performed using, for example, a polishing apparatus 52 shown in FIG.

  The polishing apparatus 52 includes a holding table (chuck table) 54 for sucking and holding the wafer 11. The holding table 54 is connected to a rotation drive source (not shown) including a motor and the like, and rotates around a rotation axis substantially parallel to the vertical direction. Further, a moving mechanism (not shown) is provided below the holding table 54, and the holding table 54 moves in the horizontal direction by this moving mechanism.

  The upper surface of the holding table 54 is a holding surface 54 a that sucks and holds the back surface 11 b side of the wafer 11. The holding surface 54 a is connected to a suction source (not shown) through a suction path (not shown) formed inside the holding table 54. By causing the negative pressure of the suction source to act on the holding surface 54 a, the wafer 11 is sucked and held by the holding table 54.

  A polishing unit 56 is disposed above the holding table 54. The polishing unit 56 includes a spindle housing (not shown) supported by an elevating mechanism (not shown). A spindle 58 is accommodated in the spindle housing, and a disc-shaped mount 60 is fixed to the lower end portion of the spindle 58.

  A polishing pad 62 having the same diameter as that of the mount 60 is attached to the lower surface of the mount 60. The polishing pad 62 includes a polishing cloth made of, for example, a nonwoven fabric or urethane foam. A rotational drive source (not shown) such as a motor is connected to the upper end side (base end side) of the spindle 58, and the polishing pad 62 is substantially parallel to the vertical direction by the rotational force generated by the rotational drive source. Rotate around the axis of rotation.

  In the resin layer thinning step, first, the back surface 11b side of the wafer 11 is brought into contact with the holding surface 54a of the holding table 54, and the negative pressure of the suction source is applied. As a result, the wafer 11 is held on the holding table 54 with the mold resin layer 23 formed on the surface 11a side exposed upward. In this resin layer thinning step, a protective member may be attached to the back surface 11b side of the wafer 11.

  Next, the holding table 54 is moved below the polishing unit 56. Then, as shown in FIG. 8A, the spindle housing (spindle 58) is lowered while rotating the holding table 54 and the polishing pad 62, respectively. The descending amount of the spindle housing is adjusted so that the lower surface (polishing surface) of the polishing pad 62 is pressed against the mold resin layer 23.

  As a result, the mold resin layer 23 (part of the mold resin layer 23 (covering portion) 23b) is polished, and the package wafer 1 with the bumps 17 exposed as shown in FIG. 8B can be completed. . FIG. 9 is a perspective view schematically showing the completed package wafer 1. In this resin layer thinning step, either wet polishing using a polishing liquid or dry polishing without using a polishing liquid may be used.

  After the molding step (resin layer thinning step), a wafer thinning step is performed in which the wafer 11 in the package wafer 1 is thinned to expose the first groove 11c on the back surface 11b side. FIG. 10A is a side view for explaining the wafer thinning step, and FIG. 10B is a cross-sectional view for explaining the wafer thinning step. In this wafer thinning step, a protective member 33 is attached in advance to the mold resin layer 23 side of the package wafer 1.

  The wafer thinning step is performed using, for example, a grinding apparatus 72 shown in FIG. The grinding device 72 includes a holding table (chuck table) 74 for sucking and holding the package wafer 1. The holding table 74 is connected to a rotation drive source (not shown) including a motor and the like, and rotates around a rotation axis substantially parallel to the vertical direction. A moving mechanism (not shown) is provided below the holding table 74, and the holding table 74 is moved in the horizontal direction by this moving mechanism.

  The upper surface of the holding table 74 is a holding surface 74 a that sucks and holds the protective member 33 attached to the mold resin layer 23 side of the package wafer 1. The holding surface 74 a is connected to a suction source (not shown) through a suction path (not shown) formed inside the holding table 74. By applying the negative pressure of the suction source to the holding surface 74a, the package wafer 1 is sucked and held by the holding table 74 via the protective member 33.

  A grinding unit 76 is arranged above the holding table 74. The grinding unit 76 includes a spindle housing (not shown) supported by an elevating mechanism (not shown). A spindle 78 is accommodated in the spindle housing, and a disc-shaped mount 80 is fixed to the lower end portion of the spindle 78.

  A grinding wheel 82 having substantially the same diameter as the mount 80 is mounted on the lower surface of the mount 80. The grinding wheel 82 includes a wheel base 84 made of a metal material such as stainless steel or aluminum. A plurality of grinding wheels 86 are annularly arranged on the lower surface of the wheel base 84. A rotary drive source (not shown) such as a motor is connected to the upper end side (base end side) of the spindle 78, and the grinding wheel 82 is substantially parallel to the vertical direction by the rotational force generated by this rotary drive source. Rotate around the axis of rotation.

  In the wafer thinning step, first, the protective member 33 attached to the mold resin layer 23 side of the package wafer 1 is brought into contact with the holding surface 74a of the holding table 74 to apply a negative pressure of the suction source. As a result, the package wafer 1 is held on the holding table 74 with the back surface 11b side of the wafer 11 exposed upward. In addition, when the protective member is affixed on the back surface 11b side of the wafer 11, this protective member is peeled off and removed in advance.

  Next, the holding table 74 is moved below the grinding unit 76. Then, as shown in FIG. 10A, the spindle housing (spindle 78) is lowered while rotating the holding table 74 and the grinding wheel 82, respectively. The descending amount of the spindle housing is adjusted so that the lower surface of the grinding wheel 86 is pressed against the back surface 11 b side of the wafer 11.

  Thereby, the back surface 11b side of the wafer 11 is ground, and as shown in FIG. 10B, the first groove 11c (and a part (filling portion) 23a of the mold resin layer 23) is exposed to the back surface 11b side. Can be made. When the wafer 11 is thinned to the finished thickness, the wafer thinning step ends.

  In the present embodiment, the wafer 11 is ground using one set of grinding units 76, but the wafer 11 can also be ground in a plurality of steps using two or more sets of grinding units. Further, the flatness of the wafer 11 may be further improved by polishing the back surface 11b side of the wafer 11 after grinding.

  After the wafer thinning step, a second groove forming step for forming a second groove based on the position of the first groove 11c estimated from the bumps 17 is performed. FIG. 11A is a partial cross-sectional side view for explaining a state in which the position of the first groove 11c is estimated in the second groove forming step, and FIG. 11B is the first groove. It is a top view for demonstrating a mode that the position of 11c is estimated.

  Before performing the second groove forming step, a dicing tape 35 (see FIG. 11A, etc.) having a diameter larger than that of the package wafer 1 is provided on the back surface 11b side of the wafer 11 constituting the package wafer 1. paste. Further, an annular frame (not shown) made of a material such as stainless steel or aluminum is fixed to the outer peripheral portion of the dicing tape 35. As a result, the package wafer 1 is supported by the annular frame via the dicing tape 35.

  As shown to FIG. 11 (A), a 2nd groove | channel formation step is implemented using the cutting device 2 mentioned above, for example. However, in the second groove forming step, it is desirable to use a cutting blade 38 that is wider (thick) than the cutting blade 36 used in the first groove forming step. Of course, a cutting blade having a width equal to or smaller than that of the above-described cutting blade 36 may be used.

  In the second groove forming step, first, the back surface 11b side (dicing tape 35) of the wafer 11 constituting the package wafer 1 is brought into contact with the holding surface 10a of the holding table 10 to apply a negative pressure of the suction source. Thus, the package wafer 1 is held on the holding table 10 with the mold resin layer 23 side exposed upward.

  Next, for example, the mold resin layer 23 side of the package wafer 1 is imaged by the camera 34 based on position information or the like registered in advance in the control unit of the cutting apparatus 2, and as shown in FIG. The macro target 19b composed of a plurality of bumps 17 necessary for estimating the position of one groove 11c (scheduled division line 13) is searched at a plurality of positions.

  In the control unit of the cutting apparatus 2, the positional relationship of the planned division line 13 with respect to the macro target 19b (for example, the distance between the macro target 19b and the planned division line 13 adjacent to the macro target 19b, etc.) is registered. Therefore, the general direction of the planned division line 13 can be specified based on the detected plurality of macro targets 19b. After specifying the general direction of the division line 13, the holding table 10 is rotated so that the direction of the division line 13 is parallel to the X-axis direction (machining feed direction).

  Next, when the position of the first groove 11c (scheduled division line 13) is estimated, the micro target 19a including one bump 17 serving as a reference is searched for at a plurality of positions. In the control unit of the cutting device 2, the positional relationship of the planned division line 13 with respect to the micro target 19a (for example, the distance between the micro target 19a and the planned division line 13 adjacent to the micro target 19a, etc.) is registered. Therefore, by searching for the micro target 19a at a plurality of positions, the position of the first groove 11c (division planned line 13) covered by the mold resin layer 23 can be estimated.

  Then, based on the estimated position of the first groove 11c, a second groove having a depth reaching the first groove 11c is formed in the outer peripheral surplus region. FIG. 12A is a partial cross-sectional side view for explaining a state in which the second groove is formed in the second groove forming step, and FIG. 12B is a diagram in which the second groove is formed. It is a top view for demonstrating a mode.

  When forming the second groove, first, the holding table 10 and the cutting unit 14 are relatively moved and rotated, and, for example, the dividing line 13 located at the boundary between the device region and the outer peripheral surplus region is changed. The cutting blade 38 is aligned above the extension line. More specifically, for example, with respect to the extension line of the first groove 11c formed in the planned dividing line 13, the protrusion protrudes toward the outer peripheral surplus area side in the width direction of the first groove 11c, but toward the device area side. The cutting blade 38 is adjusted to a position where it does not protrude.

  Further, the cutting blade 38 is lowered to a height at which the wafer 11 is slightly cut. In this state, as shown in FIG. 12A, the holding table 10 is moved in a direction parallel to the target first groove 11c (division planned line 13) while rotating the cutting blade 38 ( Processing feed). Thereby, the cutting blade 38 is cut into the outer peripheral surplus region side of the target first groove 11c, and the depth reaching the first groove 11c as shown in FIGS. 12 (A) and 12 (B). The second groove 1a can be formed.

  In this embodiment, since the cutting blade 38 wider than the cutting blade 36 is used, the second groove 1a is formed with a width wider than the width of the first groove 11c. In addition, since the boundary between a part (filling portion) 23a of the mold resin layer 23 filled in the first groove 11c and the wafer 11 is exposed through the second groove 1a, the following first first In the groove specifying step, the position of the first groove 11c can be specified with high accuracy.

  For example, after the second groove 1a extending in the first direction is formed, the holding table 10 and the cutting unit 14 are relatively moved and rotated to extend in a second direction different from the first direction. The second groove 1a is formed in the same procedure. When the second groove 1a extending in the first direction and the second groove 1a extending in the second direction are formed, the second groove forming step ends.

  In the present embodiment, the second groove 1a having a width wider than the first groove 11c is formed by using a cutting blade 38 having a width wider than that of the cutting blade 36. A second groove 1a having a width wider than that of the first groove 11c may be formed by cutting a cutting blade having the same or less width twice or more.

  After the second groove forming step, a first groove specifying step for specifying the position of the first groove 11c based on the boundary between the mold resin layer 23 and the wafer 11 exposed through the second groove 1a. To implement. FIG. 13 is a partial cross-sectional side view for explaining the first groove specifying step. As shown in FIG. 13, the first groove specifying step is also performed by the cutting device 2 described above, for example.

  In the first groove specifying step, first, the position where the second groove 1a is formed in the second groove forming step is imaged by the camera 34 and exposed through the second groove 1a as shown in FIG. The boundary between the mold resin layer 23 and the wafer 11 to be searched is found. Here, the thickness of the cutting blade 36 used when forming the first groove 11c (that is, the width of the first groove 11c) is known. Therefore, based on the boundary between the mold resin layer 23 and the wafer 11, for example, the center position in the width direction of the first groove 11 c (the position that bisects in the width direction) can be specified with high accuracy.

  After the first groove specifying step, a processing step for processing the package wafer 1 from the mold resin layer 23 side along the specified first groove 11c is performed. In this embodiment, the package wafer 1 is divided into a plurality of package devices in this processing step. 14A and 14B are side views for explaining the processing steps, and FIGS. 15A and 15B are cross-sectional views for explaining the processing steps.

  The processing step is subsequently performed by the cutting device 2. However, in this machining step, a cutting blade 40 that is narrower (thinner) than the cutting blade 36 used in the first groove forming step is used.

  Specifically, first, the holding table 10 and the cutting unit 14 are relatively moved and rotated, and the cutting blade 38 is placed above the extension line of the first groove 11c specified in the first groove forming step. Match. Further, as shown in FIG. 14A, the cutting blade 30 is lowered to a height at which it contacts the dicing tape 35.

  Then, in this state, as shown in FIGS. 14B and 15A, while rotating the cutting blade 40, in a direction parallel to the target first groove 11c (division planned line 13). The holding table 10 is moved (process feed). Thereby, the cutting blade 40 can be cut along the target first groove 11c, and the package wafer 1 can be divided.

  Here, a cutting blade 40 having a width smaller than that of the cutting blade 36 is used, and as shown in FIG. 15A, the width direction of the cutting blade 40 is set at the center position in the width direction of the first groove 11c. The center position of is aligned. Therefore, the kerf (cutting edge) 1b by the cutting blade 38 is formed only in the mold resin layer 23, and the wall surface of the first groove 11c is not exposed.

  After repeating the above procedure, for example, after dividing the package wafer 1 along all the first grooves 11c extending in the first direction, the holding table 10 and the cutting unit 14 are relatively moved and rotated. Then, the package wafer 1 is divided in the same procedure along the first groove 11c extending in the second direction. When the package wafer 1 is divided along all the first grooves 11c and a plurality of package devices 3 are completed as shown in FIG. 15B, the processing step ends.

  FIG. 15C is a perspective view schematically showing the completed package device 3. In the present embodiment, since the position of the first groove 11c can be specified with high precision based on the boundary between the mold resin layer 23 exposed through the second groove 1a and the wafer 11, for example, the kerf 1b is the first The wall surface of the first groove 11c is not exposed on the side surface of the package device 3 by being shifted from the groove 11c. Thereby, the reliability of the package device 3 can be improved.

  In the present embodiment, the kerf 1b is formed by the method of cutting the cutting blade 40 into the package wafer 1 and divided into a plurality of package devices 3. However, the method of forming the kerf 1b is not limited. For example, the kerf 1b may be formed by a method such as ablation processing in which a laser beam having a wavelength that is easily absorbed by the package wafer 1 (mold resin layer 23) is irradiated.

  As described above, in the wafer processing method according to the present embodiment, after the surface 11a side of the wafer 11 in which the first groove 11c is formed is covered with the mold resin 21 (mold resin layer 23), the first process is performed. The second groove 1a having a depth reaching the groove 11c is formed in the outer peripheral surplus region, and the boundary between the mold resin layer 23 filled in the first groove 11c and the wafer 11 is exposed through the second groove 1a. Therefore, the position of the first groove 11c can be specified with high accuracy based on the exposed boundary. That is, even when the surface 11a side of the wafer 11 where the first groove 11c is formed is covered with the mold resin 21 (mold resin layer 23), the position of the first groove 11c is specified with high accuracy and is appropriate. Can be processed.

  In addition, this invention is not limited to description of the said embodiment, A various change can be implemented. For example, in the above embodiment, the second groove 1a having the same length as the first groove 11c located at the boundary between the device region and the outer peripheral surplus region is formed, but the second groove 1c is shorter than the first groove 11c. Two grooves 1a may be formed. Further, by removing the mold resin layer 23 along the outer peripheral edge of the package wafer 1, an annular second groove 1a that overlaps the plurality of first grooves 11c can be formed.

  FIG. 16A is a perspective view for explaining the second groove forming step according to the modified example, and FIG. 16B is a plan view for explaining the second groove forming step according to the modified example. FIG. As shown in FIGS. 16A and 16B, in the second groove forming step according to the modified example, a position corresponding to an end portion of an arbitrary first groove 11c (a position corresponding to an outer peripheral surplus region). ) To form the second groove 1a.

  More specifically, the second width which is wider than the first groove 11c so that the center position in the width direction of the first groove 11c and the center position in the width direction of the second groove 1a coincide with each other. The groove 1a is formed. Also in this case, the boundary between the part 11 (filling portion) 23a of the mold resin layer 23 filled in the first groove 11c and the wafer 11 is exposed via the second groove 1a. In the groove specifying step, the position of the first groove 11c can be specified with high accuracy.

  Moreover, in the said embodiment, the molding step comprised by the resin layer formation step which forms the mold resin layer 23 in the surface 11a side of the wafer 11, and the resin layer thinning step which exposes the bump 17 from the mold resin layer 23 is carried out. Although implemented, the contents of the molding step can be changed arbitrarily. For example, the amount of the supplied mold resin 21 may be adjusted appropriately to expose the bumps 17 without thinning the mold resin layer 23.

  Moreover, in the said embodiment, although the 1st groove | channel formation step, the 2nd groove | channel formation step, the 1st groove | channel specific step, and the process step are implemented using the cutting device 2, these or some are carried out. It can also be carried out with other processing devices such as a laser processing device.

  FIG. 17 is a perspective view schematically showing a configuration example of a laser processing apparatus that can be used for the first groove forming step, the second groove forming step, the first groove specifying step, the processing step, and the like. As shown in FIG. 17, the laser processing apparatus (processing apparatus) 102 includes a base 104 that supports each structure. A support structure 106 extending in the Z-axis direction (vertical direction, height direction) is provided at the end of the base 104.

  A protruding portion 104 a protruding upward is provided at a corner portion of the base 104 away from the support structure 106. A space is formed inside the protruding portion 104a, and a cassette elevator 108 that can be raised and lowered is installed in this space. On the upper surface of the cassette elevator 108, a cassette 110 that can accommodate a plurality of wafers 11 (or package wafers 1) is placed.

  A temporary placement mechanism 112 for temporarily placing the wafer 11 described above is provided at a position close to the protruding portion 104a. The temporary placement mechanism 112 includes, for example, a pair of guide rails 112a and 112b that are approached and separated while maintaining a state parallel to the Y-axis direction (index feed direction).

  Each of the guide rails 112a and 112b includes a support surface that supports the wafer 11 (annular frame) and a side surface that is substantially perpendicular to the support surface, and the wafer 11 (drawn from the cassette 110 by the transfer mechanism (transfer unit) 114). An annular frame) is sandwiched in the X-axis direction (machining feed direction) and adjusted to a predetermined position. A gripping portion 114a for gripping the annular frame is provided on the protruding portion 104a side of the transport mechanism 114.

  A moving mechanism (processing feed mechanism, index feed mechanism) 116 is provided at the center of the base 104. The moving mechanism 116 includes a pair of Y-axis guide rails 118 arranged on the upper surface of the base 104 and parallel to the Y-axis direction. A Y-axis moving table 120 is slidably attached to the Y-axis guide rail 118.

  A nut portion (not shown) is provided on the back side (lower surface side) of the Y-axis moving table 120, and a Y-axis ball screw 122 parallel to the Y-axis guide rail 118 is screwed to the nut portion. Yes. A Y-axis pulse motor 124 is connected to one end of the Y-axis ball screw 122. When the Y-axis ball motor 122 is rotated by the Y-axis pulse motor 124, the Y-axis moving table 120 moves in the Y-axis direction along the Y-axis guide rail 118.

  A pair of X-axis guide rails 126 parallel to the X-axis direction are provided on the surface (upper surface) of the Y-axis moving table 120. An X-axis moving table 128 is slidably attached to the X-axis guide rail 126.

  A nut portion (not shown) is provided on the back surface side (lower surface side) of the X-axis moving table 128, and an X-axis ball screw 130 parallel to the X-axis guide rail 126 is screwed into the nut portion. Yes. An X-axis pulse motor (not shown) is connected to one end of the X-axis ball screw 130. When the X-axis ball screw 130 is rotated by the X-axis pulse motor, the X-axis moving table 128 moves in the X-axis direction along the X-axis guide rail 126.

  A table base 132 is provided on the surface side (upper surface side) of the X-axis moving table 128. A holding table (chuck table) 134 for sucking and holding the wafer 11 is disposed on the table base 132. Around the holding table 134, four clamps 136 for fixing an annular frame supporting the wafer 11 from four directions are provided.

  The holding table 134 is connected to a rotation drive source (not shown) such as a motor, and rotates around a rotation axis that is substantially parallel to the Z-axis direction (vertical direction, height direction). If the X-axis moving table 128 is moved in the X-axis direction by the moving mechanism 116 described above, the holding table 134 is processed and fed in the X-axis direction. If the Y-axis moving table 120 is moved in the Y-axis direction by the moving mechanism 116, the holding table 134 is indexed and fed in the Y-axis direction.

  The upper surface of the holding table 134 is a holding surface 134 a that holds the wafer 11. The holding surface 134a is formed substantially parallel to the X-axis direction and the Y-axis direction, and a suction source (not shown) is provided through a flow path (not shown) formed inside the holding table 134 and the table base 132. )It is connected to the.

  The support structure 106 is provided with a support arm 106a that protrudes toward the center side of the base 104, and a laser beam irradiation unit (processing unit) that irradiates a laser beam downward at the tip of the support arm 106a. 138 is arranged. A camera (imaging unit) 140 that images the wafer 11 is installed at a position adjacent to the laser beam irradiation unit 138.

  The laser beam irradiation unit 138 includes a laser oscillator (not shown) that pulse-oscillates a laser beam having a wavelength that absorbs the wafer 11 or the mold resin layer 23. For example, when it is desired to ablate the wafer 11 made of a semiconductor material such as silicon, a laser oscillator including a laser medium such as Nd: YAG that pulsates a laser beam having a wavelength of 355 nm can be used.

  Further, the laser beam irradiation unit 138 includes a condenser (not shown) that collects a laser beam (pulse laser beam) pulsated from a laser oscillator, and this is applied to the wafer 11 and the like held on the holding table 134. Irradiate and collect laser beam. The wafer 11 can be laser processed (ablated) along the X-axis direction by causing the holding table 134 to be processed and fed in the X-axis direction while irradiating the laser beam with the laser beam irradiation unit 138.

  The processed wafer 11 is transferred from the holding table 134 to the cleaning unit 142 by the transfer mechanism 114, for example. The cleaning unit 142 includes a spinner table 144 that sucks and holds the wafer 11 in a cylindrical cleaning space. A rotation drive source (not shown) that rotates the spinner table 144 at a predetermined speed is connected to the lower portion of the spinner table 144.

  Above the spinner table 144, an injection nozzle 146 for injecting a cleaning fluid (typically, two fluids in which water and air are mixed) toward the wafer 11 is disposed. The wafer 11 can be cleaned by rotating the spinner table 144 holding the wafer 11 and spraying a cleaning fluid from the spray nozzle 146. The wafer 11 cleaned by the cleaning unit 142 is placed on the temporary placement mechanism 112 by the transport mechanism 114 and accommodated in the cassette 110, for example.

  Components such as the transport mechanism 114, the moving mechanism 116, the holding table 134, the laser beam irradiation unit 138, the camera 140, and the cleaning unit 142 are each connected to a control unit (not shown). This control unit controls each component described above in accordance with a series of steps necessary for processing the wafer 11.

  In addition, the structure, method, and the like according to the above-described embodiment can be appropriately modified and implemented without departing from the scope of the object of the present invention.

1 Package wafer 1a Second groove 1b Calf (cut)
3 Package Device 11 Wafer 11a Front 11b Back 11c First Groove 13 Divided Line (Street)
15 Device 17 Bump (electrode bump)
21 Mold resin 23 Mold resin layer 23a Part (filling part)
23b Part (cover)
31, 35 Dicing tape 33 Protection member 2 Cutting device (processing device)
4 Base 4a Opening 6 X-axis moving table 8 Dust-proof / splash-proof cover 10 Holding table (chuck table)
10a Holding surface 12 Clamp 14 Cutting unit (processing unit)
16 Support structure 18 Cutting unit moving mechanism (index feed mechanism)
20 Y-axis guide rail 22 Y-axis moving plate 24 Y-axis ball screw 26 Z-axis guide rail 28 Z-axis moving plate 30 Z-axis ball screw 32 Z-axis pulse motor 34 Camera (imaging unit)
36, 38, 40 Cutting blade 42 Spin coater 44 Holding table (spinner table)
44a Holding surface 46 Nozzle 52 Polishing device 54 Holding table (chuck table)
54a Holding surface 56 Polishing unit 58 Spindle 60 Mount 62 Polishing pad 72 Grinding device 74 Holding table (chuck table)
74a Holding surface 76 Grinding unit 78 Spindle 80 Mount 82 Grinding wheel 84 Wheel base 86 Grinding wheel 102 Laser processing device (processing device)
104 Base 104a Protruding portion 106 Support structure 106a Support arm 108 Cassette elevator 110 Cassette 112 Temporary placement mechanism 112a, 112b Guide rail 114 Transport mechanism (transport unit)
114a Gripping part 116 Moving mechanism (machining feed mechanism, index feed mechanism)
118 Y-axis guide rail 120 Y-axis moving table 122 Y-axis ball screw 124 Y-axis pulse motor 126 X-axis guide rail 128 X-axis moving table 130 X-axis ball screw 132 Table base 134 Holding table (chuck table)
134a Holding surface 136 Clamp 138 Laser beam irradiation unit (processing unit)
140 Camera (imaging unit)
142 Cleaning unit 144 Spinner table 146 Spray nozzle

Claims (2)

A wafer processing method comprising a device region in which devices having electrode bumps are formed in a plurality of regions partitioned by a grid-like division line and a peripheral excess region surrounding the device region on the surface side,
A first groove forming step for forming a first groove having a depth equal to or greater than a finished thickness of the wafer along the division line from the surface side of the wafer;
A molding step for forming a package wafer in which the electrode bumps are exposed from the mold resin layer by filling the first groove with a mold resin and covering the surface side of the wafer with the mold resin;
After imaging the electrode bumps of the package wafer and estimating the position where the first groove is formed based on the electrode bump, the mold resin layer side based on the estimated position of the first groove A second groove having a depth extending from the first groove to the first groove is formed in the outer peripheral surplus region, so that the boundary between the mold resin layer filled in the first groove and the wafer is the second groove. A second groove forming step exposed through
A first groove identifying step for identifying a position of the first groove based on the boundary exposed through the second groove;
A processing step of processing the package wafer from the side of the mold resin layer along the identified first groove.   2. The wafer processing method according to claim 1, wherein the second groove is formed with a width wider than the width of the first groove.