JP2009054953A - Wafer processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely pick up divided individual devices from a tape when dividing a wafer by so-called prior dicing in which the wafer is divided into individual devices while exposing separation grooves from the rear-face side of the wafer by grinding the rear face of the wafer after forming the separation grooves, respectively having a depth equivalent to a finishing thickness of a device, on division-scheduled lines on the surface of the wafer. <P>SOLUTION: A wafer processing method has the following configuration. A wafer W is configured so that a protective member 2 is stuck onto the surface while separation grooves G are exposed from the rear face. The rear face of the wafer divided into devices D is stuck onto an adhesive tape T. The protective member 2 is peeled off from the surface. The adhesive tape T is stretched so as to widen an interval between the devices D adjacent to each other and to pick up the individual devices D. As the adhesive tape T, it is devised to use a tape whose thickness is thinner than that of a dicing tape used during dicing in which a cutting blade penetrates through the surface and rear face of the wafer so as to divide the wafer into devices. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wafer processing method for dividing a wafer into individual devices.

  A wafer formed by dividing devices such as ICs and LSIs by dividing lines is divided into individual devices by cutting a cutting blade that rotates at high speed in all the dividing lines.

  When the wafer is divided, the wafer is attached to the dicing tape, and the peripheral portion of the dicing tape is attached to the ring frame, so that the wafer is supported by the dicing frame via the dicing tape. Then, by performing cutting to such an extent that the cutting blade slightly cuts into the dicing tape, the planned dividing line is completely cut and divided into devices reliably. After the device is divided, the dicing tape to which the device is attached is extended in the surface direction to widen the interval between adjacent devices and pick up individual devices (see, for example, Patent Document 1).

  On the other hand, a separation groove having a depth corresponding to the finished thickness of the device is formed on the planned dividing line on the front surface of the wafer, the back surface of the wafer is ground, and the separation groove is exposed from the back surface side to each device. A technique called so-called “first dicing” is also proposed and put into practical use (see Patent Document 2). Also in this tip dicing, the back side of the wafer with the separation groove exposed from the back side is stuck to the dicing tape, and the dicing tape is stretched in the surface direction, and then the devices divided by the separation groove appearance are individually picked up. The

JP 2006-24676 A Japanese Patent Publication No. 5-54262

  Even in the above-mentioned dicing, the device is picked up after sticking the wafer with the separation groove exposed from the back surface to the dicing tape because the same device as in the case of normal dicing is used for picking up the device. The tape is formed with a relatively thick thickness of 90 μm to 120 μm by a synthetic resin such as vinyl chloride so that the cutting blade does not break even when the cutting blade is cut, and in the first dicing, no cut is formed in the dicing tape. Even if the dicing tape is extended so as to increase the distance between adjacent devices after the separation grooves are exposed, it is difficult to increase the distance between the devices, which causes a problem in pickup.

  Accordingly, the problem to be solved by the present invention is to increase the distance between adjacent devices even when the wafer is divided by so-called first dicing so that individual devices can be picked up reliably.

  The present invention relates to a wafer processing method in which a wafer having a plurality of devices formed on a surface divided by a division line is divided into individual devices, and the depth corresponding to the finished thickness of the device in the division line. A separation groove forming step for forming a separation groove, a back surface grinding step for sticking a protective member to the front surface of the wafer, grinding the back surface of the wafer to expose the separation groove from the back surface side, and a ring formed with an opening A wafer transfer process that supports the wafer with the separation groove exposed on the frame-like frame via the adhesive tape, peels off the protective member from the wafer surface, and transfers the wafer to the ring-like frame; The pick-up process picks up individual devices by widening the interval between devices to be used in the wafer transfer process. An adhesive tape, cutting blade thickness than the dicing tape stuck to the wafer at the time of dicing to be split into the device through the front and rear surfaces of the wafer is a thin tape.

  As the adhesive tape, for example, a tape made of vinyl chloride and having a thickness of 60 μm to 20 μm can be used.

  In normal dicing in which the cutting blade penetrates the front and back surfaces of the wafer, the cutting blade also cuts into the dicing tape. Therefore, the dicing tape is required to have a certain thickness in order to prevent the dicing tape from breaking. Since the cutting blade does not cut into the tape in the first dicing, there is no risk of breakage of the tape, and the adhesive tape used for the first dicing should be thinner than the dicing tape used for normal dicing Is possible. In addition, by using a thin type of adhesive tape, it is easy to expand the interval between devices by stretching the adhesive tape in the pick-up process even if the tape is not cut as in normal dicing.

  A plurality of devices D are formed on the surface W1 of the wafer W shown in FIG. A case where the wafer W is divided into individual devices D by so-called dicing will be described below.

  First, a separation groove having a thickness corresponding to the finished thickness of the device D is formed on the division line S of the wafer W. For example, a cutting device 1 shown in FIG. 2 is used to form the separation groove. The cutting apparatus 1 includes a chuck table 10 that holds a wafer W and can move in the X-axis direction, a cutting unit 11 that cuts the wafer W, and an X-axis feed unit 12 that drives the chuck table 10 in the X-axis direction. The Y-axis feeding means 13 for driving the cutting means 11 in the Y-axis direction and the Z-axis feeding means 14 for driving the cutting means 11 in the Z-axis direction are provided.

  The cutting means 11 is connected to a spindle 110 having an axis in the Y-axis direction, a housing 111 that rotatably supports the spindle 110, a cutting blade 112 mounted on one end of the spindle 110, and the other end of the spindle 110. The motor 113 is configured to rotate the spindle 110, and the cutting blade 112 is rotated as the spindle 110 is rotated by being driven by the motor 113.

  An alignment unit 15 for detecting the position of the wafer to be cut and aligning with the cutting blade 112 is fixed to the housing 111 constituting the cutting unit 1, and the alignment unit 15 is interlocked with the cutting unit 11. It has become. The alignment unit 15 includes an imaging unit 150, and a position to be cut can be detected by matching an image acquired by the imaging unit 150 with a previously stored image of the wafer. The imaging unit 150 is located on the extension line of the cutting blade 112 in the X-axis direction.

  The X-axis feed means 12 includes a ball screw 120 having an axis in the X-axis direction, a pair of guide rails 121 arranged in parallel to the ball screw 120, a motor 122 connected to one end of the ball screw 120, an internal not shown The nut is screwed into the ball screw 120 and the lower part is slidably in contact with the guide rail 121, and the rotation drive part 124 is internally fixed with the pulse motor that is fixed to the slide part 123 and rotates the chuck table 10 by a desired angle. As the ball screw 120 is rotated by being driven by the motor 122, the slide portion 123 slides on the guide rail 121 in the X-axis direction, and accordingly, the chuck table 10 also moves in the X-axis direction. It has become.

  The Y-axis feeding means 13 includes a ball screw 130 having an axis in the Y-axis direction, a pair of guide rails 131 arranged in parallel to the ball screw 130, a pulse motor 132 connected to one end of the ball screw 130, and not shown. The inner nut is screwed into the ball screw 130 and the lower part is composed of a slide part 133 that is in sliding contact with the guide rail 131. As the ball screw 130 is rotated by being driven by the pulse motor 132, the slide part 133 is moved to the guide rail. 131 is slid in the Y-axis direction, and the cutting means 11 is also moved in the Y-axis direction along with this.

  The Z-axis feeding means 14 includes a ball screw 140 having an axis in the Z-axis direction, a pair of guide rails 141 arranged in parallel to the ball screw 140, a pulse motor 142 connected to one end of the ball screw 140, and not shown. An internal nut is screwed into the ball screw 140, and a side portion is formed of a support portion 143 that slides on the guide rail 141 and supports the cutting means 11, and is driven by the pulse motor 142 to rotate the ball screw 140. The support portion 143 is guided by the guide rail 141 and moves up and down in the Z-axis direction. Accordingly, the cutting means 11 also moves up and down in the Z-axis direction.

  In forming the separation groove on the wafer division planned line S, first, the wafer W is positioned directly below the imaging unit 150 by the movement of the chuck table 10 and the alignment means 15. Then, the surface W1 of the wafer W is imaged while adjusting the positions of the chuck table 10 and the imaging unit 150, and pattern matching between the image of the wafer stored in advance in the alignment unit 15 and the actually acquired image is performed. The movement of the alignment means 15 is stopped when the two coincide. The adjustment is made in advance so that the cutting blade 112 is positioned on the extended line of the imaging unit 150 in the X-axis direction, and the alignment unit 15 including the imaging unit 150 and the cutting unit 11 are interlocked. In FIG. 5, the Y-axis direction alignment between the division line to be cut and the cutting blade 112 is performed.

  Next, the chuck table 10 is moved in the + X direction by being driven by the X-axis feed means 12, and the cutting means 11 is lowered by being driven by the Z-axis feed means 14 while the cutting blade 112 is rotating at a high speed. A separation groove that does not penetrate to the back surface W <b> 2 of the wafer W is formed by cutting into the planned division line where the blade 112 is detected. At this time, the position of the cutting means 11 in the Z-axis direction is adjusted by the Z-axis feed means 14 so that the depth of cut from the surface W1 of the wafer W, that is, the depth of the separation groove, becomes a value corresponding to the finished thickness of the device. Is precisely controlled.

  The chuck table 10 is moved in the X-axis direction while being driven by the Y-axis feed means 13 and the cutting means 11 is moved in the Y-axis direction by an interval between adjacent division lines, and the same cutting is performed. Separation grooves are formed in all the planned division lines. Further, when the same cutting as described above is performed after the chuck table 10 is rotated 90 degrees, separation grooves G are formed in all the planned division lines in the vertical and horizontal directions (separation grooves G) as in the wafer Wa shown in FIG. Forming step).

  Next, the back surface W2 of the wafer Wa on which the separation groove G is formed is ground to expose the separation groove G from the back surface W2 side. Prior to grinding of the back surface W2, as shown in FIG. 4, the protective member 2 is adhered to the front surface W1 of the wafer Wa.

  For grinding the back surface W2 of the wafer Wa, for example, a grinding device 3 shown in FIG. 5 can be used. The grinding apparatus 3 includes a chuck table 30 that holds a wafer, a grinding unit 31 that grinds the wafer held on the chuck table 30, and a grinding feed unit 32 that raises and lowers the grinding unit 31.

  The chuck table 30 can be rotated and moved in the horizontal direction, and can be moved below the grinding means 31 while holding the wafer.

  The grinding means 31 includes a spindle 310 having a vertical axis, a housing 311 that rotatably supports the spindle 310, a motor 312 that rotates the spindle 310, a wheel mount 313 formed at the lower end of the spindle 310, The grinding wheel 314 is fixed to the wheel mount 313, and a grinding wheel 315 is fixed to the lower surface of the grinding wheel 314.

  The grinding feed means 32 includes a ball screw 320 having a vertical axis, a pair of guide rails 321 arranged in parallel to the ball screw 320, a pulse motor 322 connected to one end of the ball screw 320 and rotating the ball screw 320. The inner nut is screwed to the ball screw 320 and the side portion is composed of an elevating portion 323 that is in sliding contact with the guide rail 321 and supports the grinding means 31, and is driven by the pulse motor 322 to rotate the ball screw 320. Accordingly, the elevating part 323 is guided by the guide rails 321 and moves up and down, and the grinding means 31 also moves up and down.

  As shown in FIG. 4, the wafer Wa in which the protective member 2 is adhered to the front surface W1 on which the separation groove G is formed is in a state where the protective member 2 side is held by the chuck table 30 and the back surface W2 is exposed. When the chuck table 30 moves in the horizontal direction and the wafer Wa is positioned immediately below the grinding means 31, the chuck table 30 rotates and the grinding wheel 314 rotates while being driven by the grinding feed means 32, so that the grinding means 31 is moved. As shown in FIG. 6, the rotating grinding wheel 315 contacts the back surface W2 of the wafer Wa to perform grinding.

  If grinding is continued in this way, as shown in FIG. 7, the separation grooves G are exposed from the back surface W2, and the separation grooves G penetrate the front and back surfaces of the wafer Wa and are divided into individual devices D. Each device D remains adhered to the protective member 2 and maintains the shape of the wafer Wb as a whole (back grinding process).

  Next, as shown in FIG. 8, after the rear surface side of the divided wafer Wb is attached to the adhesive tape T, the protective member 2 is peeled off and the divided wafer Wb is transferred to the adhesive tape T. Since the peripheral portion of the adhesive tape T is attached to the ring-shaped frame F in which the opening is formed, the plurality of devices D that maintain the shape of the wafer Wb as a whole are connected to the ring-shaped frame F via the adhesive tape T. It will be in the state supported by. The adhesive tape T is made of, for example, vinyl chloride and has elasticity. The adhesive tape T has a thickness of 60 to 20 μm and is formed thinner than a dicing tape to which a wafer is attached during normal dicing (transfer process).

  The plurality of devices D supported by the ring-shaped frame F via the adhesive tape T are then transported to, for example, the pickup device 4 shown in FIG.

  The pickup device 4 sucks the device D, the mounting unit 40 on which the device D integrated with the ring-shaped frame F is mounted, the drive unit 41 that moves the mounting unit 40, and the device D. And a pickup section 42 for picking up.

  The mounting unit 40 includes a cylindrical device support base 400 that supports the device D from below with an adhesive tape T, a ring-shaped frame support base 401 that supports the ring-shaped frame F from below, and a frame support base 401. And a plurality of frame fixing portions 402 that fix the ring-shaped frame F.

  The drive unit 41 includes a plurality of lift drive units 410 that lift and lower the frame support base 401, a rotation drive unit 411 that rotates the placement unit 40, and an X-axis drive unit 412 that moves the placement unit 40 in the X-axis direction. The Y-axis drive unit 413 moves the mounting unit 40 in the Y-axis direction orthogonal to the X-axis direction.

  The lifting / lowering drive unit 410 includes an air cylinder 410a and a piston 410b. The upper end of the piston 410b is fixed to the frame support base 401, and the frame support base 401 moves up and down as the piston 410b moves up and down. .

  The rotation drive unit 411 includes a turntable 411a to which the air cylinder 410a and the device support base 400 are fixed, a belt 411b wound around the outer periphery of the turntable 411a, and a drive source 411c that drives the belt 411b to rotate the turntable 411a. The device support base 400, the elevating drive unit 410, and the frame support base 401 are rotated by the rotation of the turntable 411a.

  The X-axis drive unit 412 includes a ball screw (not shown) having an axis in the X-axis direction, a guide rail 412a disposed in parallel with the ball screw, a pulse motor 412b that rotates the ball screw, and an internal nut screwed into the ball screw. The X-axis moving pedestal 412c is slidably contacted with the guide rail 412a and the X-axis moving pedestal 412c is guided by the guide rail 412a as the ball screw is rotated by being driven by the pulse motor. It is configured to move in the direction.

  The Y-axis drive unit 413 includes a ball screw 413a having an axis in the Y-axis direction, a guide rail 413b disposed in parallel to the ball screw 413a, a pulse motor 413c that rotates the ball screw 413a, and an internal nut that is a ball screw 413a. The Y-axis moving pedestal 413d is slidably contacted with the guide rail 413b, and the Y-axis moving pedestal 413d is guided by the guide rail 413b as the ball screw 413a rotates by being driven by the pulse motor 413c. Thus, it is configured to move in the Y-axis direction.

  As shown in FIG. 8, the device D supported by the ring-shaped frame F via the adhesive tape T is placed on the device support base 400 of the pickup device 4 as shown in FIG. On the other hand, the ring-shaped frame F is placed on the frame support 401 and pressed and fixed by the frame fixing unit 402.

  Next, as shown in FIG. 11, the piston 410b is lowered and the frame support base 401 is lowered to lower the frame F and extend the adhesive tape T, thereby widening the gap between the adjacent devices D. At this time, since the device D is divided by so-called tip dicing, the adhesive tape T is not cut, but since the adhesive tape T is formed thinner than the dicing tape, the device D is easily stretched and surely the device. The interval between them can be widened. Therefore, the device D can be picked up by the suction unit 42 in a state where the interval between the devices is widened.

  When the device is picked up, the adhesive tape T is stretched and the interval between the devices is widened, and the device to be picked up from the lower side through the adhesive tape T using a needle-like bar is easy to peel off the device. At the same time, the pickup means 42 picks up and picks up the device and stores it in a tray or the like (not shown). Since the interval between devices is wide, pickup can be performed smoothly.

  Further, devices are picked up one after another in the same manner as described above while being moved by the X-axis drive unit 412 and the Y-axis drive unit 413 shown in FIG. Go.

It is a perspective view which shows an example of a wafer. It is a perspective view which shows an example of a cutting device. It is a perspective view which shows the wafer in which the separation groove | channel was formed. It is a perspective view which shows the state which adheres a protection member to the wafer in which the separation groove | channel was formed. It is a perspective view which shows an example of a grinding device. It is a perspective view which shows the state which grinds the back surface of the wafer by which the protection member was stuck on the surface. It is a perspective view which shows the wafer which the protection member stuck on the surface and the isolation | separation groove | channel exposed from the back surface. It is a perspective view which shows the state which peels a protection member from the surface while sticking the back surface of the wafer divided | segmented into the device on an adhesive tape. It is a perspective view which shows an example of a pick-up apparatus. It is sectional drawing which shows schematically the state by which the device with which the ring-shaped frame was supported was fixed to the pick-up apparatus via the adhesive tape. It is sectional drawing which shows schematically the state which extended | stretched the adhesive tape and expanded the space | interval of a device. Discard

Explanation of symbols

W: Wafer W1: Front surface S: Planned division line D: Device W2: Back surface G: Separation groove 1: Cutting device 10: Chuck table 11: Cutting means 110: Spindle 111: Housing 112: Cutting blade 113: Motor 12: X axis Feed means 120: Ball screw 121: Guide rail 122: Motor 123: Slide part 124: Rotation drive part 13: Y-axis feed means 130: Ball screw 131: Guide rail 132: Pulse motor 133: Slide part 14: Z-axis feed means 140: Ball screw 141: Guide rail 142: Pulse motor 143: Support unit 15: Alignment unit 150: Imaging unit 2: Protection member 3: Grinding device 30: Chuck table 31: Grinding unit 310: Spindle 311: Housing 312: Motor 313: Wheel mount 31 : Grinding wheel 315: Grinding wheel 32: Grinding feed means 320: Ball screw 321: Guide rail 322: Pulse motor 323: Lifting unit 4: Pickup device 40: Placement unit 400: Device support base 401: Frame support base 402: Frame fixing Unit 41: Drive unit 410: Lift drive unit 410a: Air cylinder 410b: Piston 411: Rotation drive unit 411a: Turntable 411b: Belt 411c: Drive source 412: X-axis drive unit 412a: Guide rail 412b: Pulse motor 412c: X Axis moving base 413: Y axis driving unit 413a: Ball screw 413b: Guide rail 413c: Pulse motor 413d: Y axis moving base 42: Pickup unit

Claims (2)

A wafer processing method that divides a wafer having a plurality of devices formed on a surface by dividing lines into individual devices,
A separation groove forming step of forming a separation groove having a depth corresponding to the finished thickness of the device in the division line;
A back surface grinding step of attaching a protective member to the front surface of the wafer and grinding the back surface of the wafer to expose the separation groove from the back surface side;
A wafer in which the separation groove is exposed to a ring-shaped frame in which an opening is formed is supported via an adhesive tape, and the protective member is peeled off from the surface of the wafer to transfer the wafer to the ring-shaped frame. A transfer process;
The adhesive tape is stretched to widen the interval between adjacent devices and to pick up individual devices, and a pickup process,
The adhesive tape used in the wafer transfer process is thinner than the dicing tape that is attached to the wafer during dicing when the cutting blade penetrates the front and back surfaces of the wafer and is divided into devices. Processing method.   The wafer processing method according to claim 1, wherein the adhesive tape is made of vinyl chloride and has a thickness of 60 μm to 20 μm.

Images