JP6594241B2 - Wafer processing method - Google Patents

Description

  The present invention relates to a wafer processing method including a device having a key pattern and electrode bumps connected to the device.

  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 technique has been proposed in which a groove is formed along a line to be divided and a mold resin for covering the surface side is filled in the groove so that the wafer is not exposed around the package device (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 direction of the division planned line cannot be specified based on the characteristic pattern (key pattern) of the device. Although it may be possible to specify the position and orientation of the line to be divided based on the bumps (electrode bumps) exposed from the mold resin, this method does not necessarily plan to divide due to variations in the shape and position of the bumps. The position and orientation of the line could not be specified with high accuracy.

  The present invention has been made in view of such problems, and the object of the present invention is to accurately identify and process the dividing line with high precision even when the surface side of the wafer is coated with a mold resin. It is to provide a wafer processing method.

  According to one aspect of the present invention, there is provided a wafer processing method including a device having a key pattern and an electrode bump connected to the device in a region on the surface side defined by a plurality of intersecting division lines. , Image the key pattern of the wafer held in a manner that the surface side is exposed to a rotatable holding table, determine the direction of the line to be divided, and the processing feed direction and division when processing the wafer by rotating the holding table A registration step of registering a positional relationship between an electrode bump corresponding to a predetermined device and a division planned line partitioning the device and a shape of the electrode bump related to the positional relationship after making the direction of the planned line parallel to each other; A groove having a depth greater than the finished thickness of the wafer is formed along the planned dividing line from the front surface side of the wafer held by the holding table. After performing the groove forming step, the registration step, and the groove forming step, the groove is filled with a mold resin, and the surface side of the wafer is covered with the mold resin so that the electrode bumps are removed from the mold resin layer. A molding step for forming an exposed package wafer, and after performing the molding step, hold the package wafer in a manner in which the mold resin layer side is exposed using the holding table or a holding table different from the holding table, After detecting the electrode bumps related to the positional relationship registered in the registration step and determining the direction of the division planned line based on the positional relationship, the electrode bumps along the planned division line calculated based on the positional relationship are determined. A processing step of processing the package wafer from the mold resin layer side. Method for processing Eha is provided.

  In the wafer processing method according to one aspect of the present invention, before the front surface side of the wafer is coated with the mold resin, the processing feed direction and the direction of the division planned line are parallel, and the electrode bumps corresponding to a predetermined device Since the positional relationship with the planned division line and the shape of the electrode bump related to this positional relationship are registered, even after the front surface side of the wafer is covered with the mold resin, the divided line is determined based on the electrode bump related to this positional relationship. The direction can be specified with high accuracy.

  That is, according to the wafer processing method according to one aspect of the present invention, the electrode bump shapes necessary for specifying the direction of the division line are individually registered, and therefore, based on the general shape of the electrode bumps. Thus, compared to the case where the direction of the planned division line is specified, the division planned line can be specified with high accuracy and appropriately processed even when the variation in the shape of the electrode bump is large.

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 is a side view for explaining the registration step, and FIG. 3B is a plan view for explaining the registration step. 4A, 4B, and 4C are partial cross-sectional side views for explaining the groove forming step. 5A and 5B are cross-sectional views for explaining the groove forming step. It is a perspective view which shows typically the wafer after a groove | channel formation step. FIGS. 7A and 7B are side views for explaining the resin layer forming step during the molding step, and FIG. 7C 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. 9A is a side view for explaining the resin layer thinning step during the molding step, and FIG. 9B 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. 11A is a side view for explaining the wafer thinning step, and FIG. 11B is a cross-sectional view for explaining the wafer thinning step. FIG. 12A is a side view for explaining a specific step in the processing step, and FIG. 12B is a plan view for explaining the specific step. FIG. 13 (A) and FIG. 13 (B) are side views for explaining the division step in the processing step. 14A and 14B are cross-sectional views for explaining the dividing step, and FIG. 14C is a perspective view schematically showing a completed package device. 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 this embodiment includes a registration step (see FIGS. 3A and 3B), a groove forming step (FIGS. 4A, 4B, 4C), 5 (A), FIG. 5 (B) and FIG. 6), molding step (FIG. 7 (A), FIG. 7 (B), FIG. 7 (C), FIG. 8, FIG. 9 (A), FIG. B) and FIG. 10), wafer thinning step (see FIGS. 11A and 11B) and processing step (FIGS. 12A, 12B, 13A, and 13). (B), FIG. 14 (A), FIG. 14 (B) and FIG. 14 (C)).

  In the registration step, first, an image of a key pattern of a wafer including a device having a key pattern and bumps (electrode bumps) connected to the device is picked up, and the direction of the division planned line is specified. Then, after making the processing feed direction when processing the wafer parallel to the direction of the planned dividing line, the cutting device shows the positional relationship between the bump corresponding to the predetermined device and the planned dividing line dividing the device. Register in (processing equipment).

  In the groove forming step, a groove having a depth equal to or larger 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 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 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 processing step, the electrode bumps related to the positional relationship registered in the registration step are detected, the direction of the planned division line is specified based on this positional relationship, and then the package wafer is processed along the planned division line. 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 registration step for registering information necessary for specifying the division planned line set in 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.

  Each device 15 includes a key pattern (not shown) having a characteristic shape. Further, 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 registration 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 illustrating a configuration example of a cutting apparatus in which a registration 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.

  FIG. 3A is a side view for explaining the registration step, and FIG. 3B is a plan view for explaining the registration step. In the registration step, first, the wafer 11 is placed on the holding surface 10a of the holding table 10 so that the surface 11a side is exposed upward, and a negative pressure of the suction source is applied. Further, the annular frame is fixed by the clamp 12. As a result, the wafer 11 is held on the holding table 10.

  Next, the front surface 11a side of the wafer 11 is imaged at a plurality of positions using the camera 34, and the key pattern in the device 15 is searched at the plurality of positions. Based on the coordinate information of the plurality of key patterns, the direction of the scheduled division line 13 is specified (determined). In the control unit of the cutting apparatus 2, information on the position to be imaged by the camera 34, information on the positional relationship between the key pattern and the division line 13 and the like are registered (stored) in advance.

  Therefore, based on the coordinate information of a plurality of key patterns obtained by imaging the front surface 11a side of the wafer 11, the direction of the scheduled division line 13 can be specified. In addition, as the information regarding the positional relationship between the key pattern and the planned division line 13, for example, the distance from the key pattern to the planned division line 13 can be used.

  After specifying the 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). For example, as shown in FIG. 3A, the surface 11a side of the wafer 11 is imaged at a plurality of positions, and a plurality of captured images each including an arbitrary device 15 as a target are obtained.

  Thereafter, based on the obtained plurality of captured images, information on the positional relationship between the bumps 17 corresponding to the target device 15 and the division lines 13 that divide the target device 15 is controlled by the cutting apparatus 2. Register with the unit. Specifically, for example, as shown in FIG. 3B, a micro target 19a including one bump 17 existing on the target device 15 and a planned dividing line 13 adjacent to the micro target 19a. The distance is registered in the control unit of the cutting device 2.

  In addition, information on the position, shape, and the like of the micro target 19a (one bump 17) is individually registered in the control unit of the cutting apparatus 2. In this case, in order to easily detect the micro target 19a later, the macro target 19b including a plurality of bumps 17 existing on the target device 15 and the planned division line 13 adjacent to the macro target 19b And the information on the position and shape of the macro target 19b (the plurality of bumps 17) may be registered in the control unit of the cutting apparatus 2 together.

  After the registration step, a groove forming step is performed in which a groove having a depth greater than the finished thickness obtained by dividing the wafer 11 is formed along the planned dividing line 13. 4 (A), 4 (B) and 4 (C) are partial cross-sectional side views for explaining the groove forming step, and FIGS. 5 (A) and 5 (B) are groove forming. It is sectional drawing for demonstrating a step.

  4A, 4B, and 4C 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. 5A and 5B show a cross section perpendicular to the division line 13 in which the groove is formed. As shown in FIG. 4A and the like, the groove forming step is continuously performed by the cutting device 2.

  Specifically, first, the holding table 10 and the cutting unit 14 are relatively moved and rotated, and the cutting blade 36 is aligned above the extension line of the target division planned line 13. Next, as shown in FIG. 4A, 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. 4B and 5A, the holding table 10 is moved (processed) in a direction parallel to the target division line 13 while rotating the cutting blade 36. Feed). Thereby, the cutting blade 36 is cut along the target division line 13, and as shown in FIGS. 4C and 5B, the groove 11 c having a depth greater than the finished thickness can be formed.

  After the above procedure is repeated and, for example, the grooves 11c are formed along all the planned dividing lines 13 extending in the first direction, the holding table 10 and the cutting unit 14 are relatively moved and rotated, and the first The 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 grooves 11c are formed along all the planned dividing lines 13, the groove forming step ends.

  FIG. 6 is a perspective view schematically showing the wafer 11 after the groove forming step. After the groove forming step, for example, the dicing tape 31 is peeled off from the wafer 11 and removed. In the present embodiment, the groove 11c is formed by a method of cutting the cutting blade 36 into the wafer 11, but the method for forming the groove 11c is not limited. For example, the grooves 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 groove forming step, a molding step for filling the groove 11c with mold resin and coating the surface 11a side of the wafer 11 with the mold resin to form a package wafer in which the bumps 17 are exposed from the mold resin layer is performed. carry out. 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.

  FIGS. 7A and 7B are side views for explaining the resin layer forming step during the molding step, and FIG. 7C 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. 7 (A) and 7 (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. 7A, the liquid mold resin 21 is dropped from the nozzle 46, and the holding table 44 is rotated as shown in FIG. 7B. 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 groove 11c is formed on the surface 11a side of the wafer 11, the mold resin 21 is also filled in the groove 11c as shown in FIG. That is, a part (filling part) 23a of the mold resin layer 23 (mold resin 21) is filled in the groove 11c, and another part (covering part) 23b of the mold resin layer 23 (mold resin 21) is filled. The surface 11a side of the wafer 11 is covered.

  Then, if the mold resin layer 23 is hardened by a method such as heating, the resin layer forming step is completed. FIG. 8 is a perspective view schematically showing the wafer 11 after the resin layer forming step. As shown in FIG. 8, the bump 17 is entirely covered with the mold resin layer 23 at the stage where the resin layer forming step is completed.

  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. 9A is a side view for explaining the resin layer thinning step, and FIG. 9B 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. 9A, 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. 9B can be completed. . FIG. 10 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 grooves 11c on the back surface 11b side. FIG. 11A is a side view for explaining the wafer thinning step, and FIG. 11B 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 protection member 33 attached to 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 package wafer 1 is brought into contact with the holding surface 74a of the holding table 74, and a negative pressure of the suction source is applied. 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. 11A, 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.

  As a result, the back surface 11b side of the wafer 11 is ground to expose the groove 11c (and a part (filling portion) 23a of the mold resin layer 23) to the back surface 11b side, as shown in FIG. 11B. it can. 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, after specifying the direction of the planned dividing line 13 based on the bumps 17, a processing step for processing the package wafer 1 along the specified divided planned line 13 is performed. This processing step includes, for example, a specifying step that specifies the direction of the division line 13 and a division step that divides the package wafer 1 along the division line 13.

  Before performing the processing step, a dicing tape 35 (see FIG. 12A, etc.) having a diameter larger than that of the package wafer 1 is attached to the back surface 11b side of the wafer 11 constituting the package wafer 1. 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.

  FIG. 12A is a side view for explaining a specific step in the processing step, and FIG. 12B is a plan view for explaining the specific step. As shown to FIG. 12 (A), a specific step is implemented using the cutting device 2 mentioned above, for example.

  In the specific step, first, the package wafer 1 is placed on the holding surface 10a of the holding table 10 so that the mold resin layer 23 side is exposed upward, and the negative pressure of the suction source is applied. Further, the annular frame is fixed by the clamp 12. As a result, the package wafer 1 is held on the holding table 10.

  Next, as shown in FIG. 12 (A), the mold resin layer 23 side of the package wafer 1 is imaged by the camera 34 based on the information registered in the control unit of the cutting device 2, and FIG. 12 (B). As shown, the macro target 19b is searched for at a plurality of positions registered in advance.

  In the control unit of the cutting apparatus 2, information related to the positional relationship between the bump 17 corresponding to the target device 15 and the planned division line 13 that partitions the target device 15 is registered. Specifically, the distance between the macro target 19b and the planned division line 13 adjacent to the macro target 19b 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, the micro target 19a is searched for at a plurality of positions. In the control unit of the cutting apparatus 2, information related to the positional relationship between the bump 17 corresponding to the target device 15 and the planned division line 13 that partitions the target device 15 is registered. Specifically, for example, the distance between the micro target 19a and the planned division line 13 adjacent to the micro target 19a is registered.

  Therefore, based on the detected plurality of micro targets 19a, the position and orientation of the scheduled division line 13 can be specified. When the position and orientation of the planned dividing line 13 are specified, the specifying step ends. In the present embodiment, for example, even when the positions and shapes of the bumps 17 constituting the micro target 19a vary, the direction of the division planned line 13 using the micro targets 19a (bumps 17) individually registered in advance. And position can be identified with high accuracy.

  After the specific step, a dividing step of dividing the package wafer 1 along the scheduled dividing line 13 is performed. FIGS. 13A and 13B are side views for explaining the dividing step in the processing step, and FIGS. 14A and 14B are cross-sectional views for explaining the dividing step. FIG.

  The dividing step is subsequently performed by the cutting device 2. However, in this dividing step, a cutting blade 38 that is narrower (thinner) than the cutting blade 36 used in the groove forming step is used.

  Specifically, first, the holding table 10 is rotated so that the direction of the scheduled division line 13 specified in the specific step is parallel to the X-axis direction (machining feed direction). Next, the holding table 10 and the cutting unit 14 are relatively moved, and the cutting blade 38 is aligned above the extension line of the target groove 11c.

  Then, as shown in FIG. 13A, the cutting blade 38 is lowered to a height at which it contacts the dicing tape 35. Further, in this state, as shown in FIGS. 13B and 14A, the holding table 10 is moved in a direction parallel to the target groove 11c (machining feed) while the cutting blade 38 is rotated. Let

  Thereby, the cutting blade 38 is cut along the target groove 11c, and the package wafer 1 can be divided. Here, a cutting blade 38 having a width smaller than that of the cutting blade 36 is used, and the center of the cutting blade 38 in the width direction is positioned at the center of the groove 11c in the width direction as shown in FIG. The position is adjusted. Therefore, the kerf (cutting edge) 1a by the cutting blade 38 is formed only in the mold resin layer 23, and the wall surface of the groove 11c is not exposed.

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

  FIG. 14C is a perspective view schematically showing the completed package device 3. In the present embodiment, since the direction of the division line 13 can be specified with high accuracy based on the bumps 17, for example, the kerf 1 a is displaced from the groove 11 c and the wall surface of the groove 11 c is exposed on the side surface of the package device 3. Absent. Thereby, the reliability of the package device 3 can be improved.

  In the present embodiment, the kerf 1a is formed by cutting the package blade 1 into the package wafer 1 and divided into a plurality of package devices 3. However, the method for forming the kerf 1a is not limited. For example, the kerf 1a can 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 applied.

  As described above, in the wafer processing method according to the present embodiment, before the surface 11a side of the wafer 11 is covered with the mold resin 21, the processing feed direction and the direction of the scheduled dividing line 13 are set in parallel to each other. Since the positional relationship between the bump (electrode bump) 17 corresponding to the device 15 and the line to be divided 13 and the shape of the bump 17 related to this positional relationship are registered, the surface 11 a side of the wafer 11 is coated with the mold resin 21. Moreover, the direction of the division | segmentation scheduled line 13 can be pinpointed with high precision based on the bump 17 which concerns on this positional relationship.

  That is, according to the wafer processing method according to the aspect of the present invention, the shape of the bump 17 necessary for specifying the direction of the division line 13 is individually registered. Compared with the case where the direction of the planned dividing line 13 is specified based on the above, the divided planned line 13 can be specified with high accuracy and appropriately processed even when the variation in the shape of the bump 17 is large.

  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 groove forming step is performed after the registration step, but the registration step may be performed after the groove forming step.

  Moreover, in the said embodiment, although the molding step comprised by the resin layer formation step which forms the mold resin layer 23, and the resin layer thinning step which exposes the bump 17 from the mold resin layer 23 is implemented, The content of the 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 registration step, the groove | channel formation step, and the processing step are implemented using the cutting device 2, it is also possible to implement a part or all of these with other processing devices such as a laser processing device. it can.

  FIG. 15 is a perspective view schematically showing a configuration example of a laser processing apparatus that can be used for a registration step, a groove formation step, a processing step, and the like. As shown in FIG. 15, 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.

  It should be noted that the registration step, the groove forming step, and a part of the machining step are performed by the cutting device 2, and the registration step, the groove forming step, and the remaining part of the processing step are performed by the laser processing device 102. Information registered in the step needs to be shared by the cutting device 2 and the laser processing device 102.

  In this case, for example, information registered in one of the cutting device 2 and the laser processing device 102 may be notified to the other. Further, a processing system including the cutting device 2 and the laser processing device 102 may be constructed, and information may be registered in a server or the like that controls the entire processing system.

  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 Calf (cut)
3 Package Device 11 Wafer 11a Front 11b Back 11c 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 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 (1)

A method of processing a wafer comprising a device having a key pattern and an electrode bump connected to the device in a region on the surface side defined by a plurality of division lines to intersect,
Image the key pattern of the wafer held in a manner that the surface side is exposed on a rotatable holding table to determine the direction of the planned dividing line, and the processing feed direction and the dividing schedule when processing the wafer by rotating the holding table A registration step of registering the positional relationship between the electrode bumps corresponding to a predetermined device and the division-scheduled lines partitioning the device, and the shape of the electrode bumps related to the positional relationship after making the direction of the line parallel;
A groove forming step of forming a groove having a depth equal to or greater than a finished thickness of the wafer from the surface side of the wafer held by the holding table along the division line;
After performing the registration step and the groove forming step, the 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 the electrode bumps are exposed from the mold resin layer. Molding steps,
After performing the molding step, the package wafer is held in a manner in which the mold resin layer side is exposed using the holding table or a holding table different from the holding table, and the positional relationship registered in the registration step is Processing for detecting the electrode bump and determining the direction of the planned dividing line based on the positional relationship, and then processing the package wafer from the mold resin layer side along the planned dividing line determined based on the positional relationship And a wafer processing method.