JP2012023175A - Wafer processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer processing method which can easily remove a ring-shaped reinforcement portion without damages from a wafer on which the ring-shaped reinforcement portion having a thickness thicker than that of a device region is formed on a peripheral side of the device region.SOLUTION: The wafer processing method comprises steps of integrating a surface of a wafer W on which a ring-shaped reinforcement part W4 is formed with a frame F1 by sticking the surface to a dicing tape T1, cutting the wafer W as it is at a boundary portion W12 between a device region W1 and the ring-shaped reinforcement portion W4 together with the dicing tape T1 to separate the ring-shaped reinforcement part W4 from the device region W1 and removing the ring-shaped reinforcement part W4 together with the frame F. Since the ring-shaped reinforcement part W4 is removed in a state where the ring-shaped reinforcement part W4 is integrated with the frame F1 via the dicing tape T1, the ring-shaped reinforcement part W4 can be removed in a short time without damaging the ring-shaped reinforcement part W4. Since the ring-shaped reinforcement part W4 is not damaged, the device region W1 is prevented from damages.

Description

  The present invention relates to a method for removing a ring-shaped reinforcing portion from a wafer in which a ring-shaped reinforcing portion is formed around the device region by grinding the back surface of the device region.

  A wafer on which a plurality of devices such as IC and LSI are formed on the surface side is divided into individual devices using a dicing apparatus or the like, and is widely used by being incorporated into various electronic devices. In order to reduce the size and weight of electronic equipment, the wafer before being divided into individual devices is formed such that the back surface is ground and the thickness thereof is, for example, 100 μm to 50 μm. In addition, a technique for improving the function by laminating a plurality of devices formed in this manner has been proposed and put into practical use (for example, see Patent Document 1).

  If the wafer is thinly processed, it becomes difficult to handle the subsequent wafer. Therefore, only the back side of the device area of the wafer is ground to form a ring-shaped reinforcing part around it, facilitating subsequent wafer handling. The invention has been proposed by the present applicant and put into practical use (for example, see Patent Document 2).

JP 2003-249620 A JP 2007-19461 A

  However, when the ring-shaped reinforcing portion is removed after separating the device region and the ring-shaped reinforcing portion, the ring-shaped reinforcing portion may be damaged, and there is a problem that it takes time for the removal work. Further, when the ring-shaped reinforcing portion is broken, the device region may be damaged. Furthermore, there is a problem that a special device for removing the ring-shaped reinforcing portion is required. Thus, various difficulties are involved in removing the ring-shaped reinforcing portion.

  The present invention has been made in view of such problems, and its object is to break a ring-shaped reinforcing portion in a wafer in which a ring-shaped reinforcing portion thicker than the device region is formed on the outer peripheral side of the device region. It is to be able to be easily removed without any problems.

The present invention relates to a wafer in which a device region in which a plurality of devices are formed and an outer peripheral surplus region surrounding the device region are formed on the front surface. The method includes a step of forming a ring-shaped reinforcing portion, and relates to a wafer processing method of removing the ring-shaped reinforcing portion after performing predetermined processing on the wafer on which the ring-shaped reinforcing portion is formed. At least the following steps including.
(1) A frame disposing step in which a wafer is accommodated in an opening of a frame having an opening for accommodating a wafer, a dicing tape is attached to the surface and the frame of the wafer, and the wafer is supported on the frame via the dicing tape. ,
(2) A ring shape in which a wafer supported by a frame is held on a holding table, and a boundary portion between the ring-shaped reinforcing portion and the device region is cut with a dicing tape by a cutting blade to separate the device region and the ring-shaped reinforcing portion. Reinforcement part separation process,
(3) A ring-shaped reinforcing portion removing step of removing the ring-shaped reinforcing portion by separating the ring-shaped reinforcing portion supported by the frame via the dicing tape from the holding table together with the frame.

  In the ring-shaped reinforcing part separating step, if the holding table has an annular relief groove for releasing the cutting blade of the cutting blade at a position corresponding to the boundary between the ring-shaped reinforcing part and the device region, Before cutting the boundary between the reinforced portion and the device area together with the dicing tape to separate the device area and the ring-shaped reinforcing portion, avoid the clearance groove and cut the inside of the boundary with a cutting blade. It is desirable to cut the dicing tape without penetrating it to separate the ring-shaped reinforcing portion from the device region. After the ring-shaped reinforcing portion removing step, a dividing step of dividing a wafer consisting only of device regions held on the holding table into individual devices is performed.

  After the ring-shaped reinforcing portion removing step, the wafer consisting only of the device region is accommodated in the opening portion of the frame having the opening portion accommodating the wafer consisting only of the device region held on the holding table, and dicing is performed on the back surface and the frame of the wafer. A dividing step of attaching a tape and supporting the wafer on the frame via a dicing tape to divide the wafer into individual devices may be performed.

  In the present invention, the surface of the wafer on which the ring-shaped reinforcing portion is formed is attached to the dicing tape and integrated with the frame, and in this state, the boundary between the device region and the ring-shaped reinforcing portion is cut together with the dicing tape. Since the device region and the ring-shaped reinforcing portion are separated and then the ring-shaped reinforcing portion is removed together with the frame, the ring-shaped reinforcing portion can be removed while being integrated with the frame via the dicing tape. . Therefore, it can be removed in a short time without damaging the ring-shaped reinforcing portion. Further, since the ring-shaped reinforcing portion is not damaged, it is possible to prevent the device region from being damaged.

  Further, before cutting the boundary between the device region and the ring-shaped reinforcing portion, the device region and the ring are previously cut by cutting the wafer so as not to completely cut the dicing tape in the region where there is no escape groove inside the boundary. By separating the shape reinforcing portion, chatter vibration can be prevented from occurring due to the influence of the relief groove formed in the holding table, and back surface chipping can be prevented from occurring on the outer periphery of the device region. .

It is a disassembled perspective view which shows a wafer and a protection member. It is a perspective view which shows the state by which the protection member was stuck on the surface of the wafer. It is a perspective view which shows the process of forming a ring-shaped reinforcement part in a wafer. It is a perspective view which shows the wafer in which the ring-shaped reinforcement part was formed. It is sectional drawing which shows the wafer in which the ring-shaped reinforcement part was formed. It is a disassembled perspective view which shows the state with which the wafer in which the ring-shaped reinforcement part was formed was supported by the flame | frame, and the holding table of a cutting device. It is a perspective view which shows the state which cuts the boundary part of a device area | region and a ring-shaped reinforcement part in a ring-shaped reinforcement part isolation | separation process. It is sectional drawing which shows the 1st modification of a ring-shaped reinforcement part isolation | separation process. It is sectional drawing which shows the 2nd modification of a ring-shaped reinforcement part isolation | separation process. It is sectional drawing which shows the 3rd modification of a ring-shaped reinforcement part isolation | separation process. It is a perspective view which shows the state which removes a ring-shaped reinforcement part with a flame | frame. It is a perspective view which shows the state which divides | segments the wafer which consists only of a device area | region. It is a perspective view which shows the state which affixes a dicing tape on the wafer which consists only of a device area | region, and is integrated with a flame | frame. It is a perspective view which shows the state which peels a protection member from the wafer which is supported by the flame | frame and consists only of a device area | region. It is a perspective view which shows the state which divides | segments the wafer which is supported by the flame | frame and consists only of a device area | region.

  On the surface Wa of the wafer W shown in FIG. 1, a plurality of devices D are formed by being partitioned by streets S, and a portion where the devices D are formed constitutes a device region W1. Further, an outer peripheral surplus region W2 that is a region where no device is formed is formed on the outer peripheral side of the device region W1, and the device region W1 is surrounded by the outer peripheral surplus region W2, and is formed by the boundary portion W12. The device area W1 and the outer peripheral surplus area W2 are partitioned.

(1) Protective Member Adhering Step When polishing the back surface Wb of this wafer W, the protective member 1 made of tape or the like is attached to the front surface Wa of the wafer W to protect the device D, and the state shown in FIG. And FIG. 2 shows a state where the protective member 1 is attached to the front surface Wa of the wafer W and the front and back sides are reversed.

(2) Back surface grinding step Next, the portion corresponding to the device region W1 of the back surface Wb of the wafer W, that is, the back side of the device region 1 is ground to a desired thickness. For such grinding, for example, a grinding apparatus 2 shown in FIG. 3 can be used.

  The grinding apparatus 2 includes a holding table 20 that holds a wafer and a grinding unit 21 that performs grinding on the wafer held on the holding table 20. The grinding unit 21 includes a rotary shaft 22 having a vertical axis, a wheel 23 attached to the lower end of the rotary shaft 22, and a grindstone portion 24 fixed to the lower surface of the wheel 23. The grindstone 24 has a diameter of the outermost circumference of the rotating track larger than the radius of the device region W1 and smaller than a diameter of the device region W1, and a diameter of the innermost circumference of the rotating track is smaller than the radius of the device region W1. It is formed to become.

  The wafer W is in a state where the protective member 1 side is held by the holding table 20 and the back surface Wb is exposed. Then, as the holding table 20 rotates and the grinding unit 21 descends while the wheel 23 rotates, the rotating grindstone unit 24 comes into contact with the back surface Wb of the rotating wafer W to perform grinding. At this time, control is performed so that the grindstone portion 24 is always brought into contact with the rotation center of the back surface of the wafer W and is not brought into contact with the back surface of the outer peripheral surplus area W2.

  By such control, only the back surface side of the device region W1 out of the back surface Wb is ground, and as shown in FIGS. 4 and 5, a ground surface W3 is formed on the back surface Wb, and on the back side of the outer peripheral surplus region W2. The ring-shaped reinforcing portion W4 having the same thickness as before grinding remains. For example, the width of the ring-shaped reinforcing portion W4 may be about 2 to 3 mm. The thickness of the ring-shaped reinforcing portion W4 is preferably about 700 μm, for example. On the other hand, the thickness of the device region W1 can be reduced to, for example, about 30 μm. After completion of the back grinding process, the protective member 1 is peeled off from the front surface Wa of the wafer W.

(3) Optional Step In addition, when a plurality of chips are laminated after dividing the wafer W, TSV (Through Silicon Via) processing is performed on each device D in the device region W1 after the back surface grinding step. Further, after the back surface grinding step, a metal film made of gold, silver, titanium or the like is formed on the grinding surface W3 by vapor deposition or the like.

(4) Frame Arrangement Step Next, the wafer W is accommodated in the opening F10 of the annular frame F1 shown in FIG. 6, and the dicing tape T1 is adhered to the surface Wa of the wafer W and the frame F1. Thus, the opening F10 is closed, and the wafer W is supported by the frame F1 through the dicing tape T1. In this state, the back surface Wb side of the wafer W is exposed.

  The wafer W thus supported by the frame F1 is held on the holding table 30 of the cutting device 3. The holding table 30 includes a vacuum region 300 made of glass, an annular relief groove 301 formed on the outer peripheral side of the vacuum region 300, and a frame support portion 302 formed on the outer peripheral side of the escape groove 301. Composed. The escape groove 301 is located below the boundary W12 between the device region W1 and the outer peripheral surplus region W2 in a state where the wafer W is held. The holding table 30 is connected to the rotation driving unit 32 via the rotation shaft 31, and the holding table 30 can be rotated by driving by the rotation driving unit 32. Below the holding table 30, an imaging means 33 is provided for imaging and detecting an area to be cut of the wafer W through the frame support 302. The wafer W supported by the frame F1 via the dicing tape T1 is sucked in the vacuum region 300 on the dicing tape T1 side, and the back surface Wb of the wafer W is exposed. If the imaging means 33 is not disposed below the holding table 30 but disposed above, the boundary portion W12 is imaged to detect a region to be cut.

  The cutting device 3 includes a cutting means 34 shown in FIG. The cutting means 34 includes a spindle 340 having a horizontal rotation axis, a cutting blade 341 mounted on the spindle 340, and a cutting water nozzle 342 that supplies cutting water to the cutting blade 341.

(5) Ring-shaped reinforcing part separating step As shown in FIG. 7, the rotating cutting blade 341 rotates so that the cutting edge of the cutting blade 341 is accommodated in the escape groove 301 shown in FIG. Is cut slightly inside the boundary portion W12 between the device region W1 and the outer peripheral surplus region W2. If it does so, it will cut | disconnect circularly and the device area | region W1 and the ring-shaped reinforcement part W4 will be isolate | separated.

  Before cutting the boundary portion W12 so that the cutting blade 341 is accommodated in the escape groove 301, as shown in FIG. 8, the cutting blade 341 penetrates the wafer W while avoiding the escape groove 301 and the dicing tape T1. It is desirable to cut to the depth which does not penetrate through and to cut the inside of the boundary part W12 ((1) of FIG. 8). When cutting is performed in this manner, the device region W1 and the ring-shaped reinforcing portion W4 are separated in advance. Then, the boundary portion W12 is cut together with the dicing tape T1 so that the cutting blade 341 is accommodated in the escape groove 301 ((2) in FIG. 8). When the two-stage cutting is performed in this way, the device region W1 is separated from the ring-shaped reinforcing portion W4 by the first-stage cutting, and thus chatter vibration occurs during the second-stage cutting due to the influence of the escape groove 301. However, since it is not transmitted to the device region W1, chipping can be prevented from occurring on the back surface of the device region W1.

  In the two-stage cutting shown in FIG. 8, the cutting position of the first-stage cutting and the cutting position of the second-stage cutting are separated, so the cutting position of the first-stage cutting and the cutting position of the second-stage cutting are different. The ring-shaped ring end material W5 remains between the cutting positions. Therefore, it is desirable to perform three-stage cutting as shown in FIG. First, in the first-stage cutting, similarly to the example shown in FIG. 8, the inside of the boundary portion W12 is cut by avoiding the escape groove 301 so that the cutting blade 341 penetrates the wafer W ((1 in FIG. 9). )). Next, in the second-stage cutting, the outside of the cutting portion in the first-stage cutting is cut so as to avoid the escape groove 301 so that the cutting blade 341 penetrates the wafer W ((2) in FIG. 9). Finally, in the third-stage cutting, the outside of the cutting portion in the second-stage cutting is cut so that the cutting blade 341 is accommodated in the escape groove 301 ((3) in FIG. 9). By performing the first, second, and third stage cutting without gaps, it is possible to avoid the formation of a ring-shaped ring end material.

  As a method for preventing the ring-shaped ring end material 5 from being generated, as shown in FIG. 10, avoid the escape groove 301 so that the cutting blade 341 penetrates the wafer W in the first stage cutting. The inside of the boundary portion W12 is cut ((1) in FIG. 10), and in the second stage cutting, the cutting blade 341 avoids the escape groove 301 so that the cutting blade 341 penetrates the wafer W. (2 in FIG. 10), and in the third-stage cutting, the ring-shaped reinforcing portion W4 is arranged so that the cutting blade 341 is accommodated in the escape groove 301 outside the cutting portion in the second-stage cutting. In addition, the outside of the boundary portion W12 may be cut (see (3) in FIG. 10).

(6) Ring-shaped reinforcement part removal process Next, as shown in FIG. 11, the ring-shaped reinforcement part W4 is removed from the device area | region W1. The ring-shaped reinforcing portion W4 is attached to the dicing tape T1, and since the frame F1 is attached to the dicing tape T1, the ring-shaped reinforcing portion W4 is removed together with the dicing tape T1 simply by lifting the frame F1. can do. Therefore, a special device for removing the ring-shaped reinforcing portion W4 is unnecessary, and the ring-shaped reinforcing portion W4 is not damaged and the removal work does not take time, and the ring-shaped reinforcing portion W4 is damaged. And the device area is not damaged. When the ring-shaped reinforcing portion W4 is removed together with the dicing tape T1 and the frame F1 by the ring-shaped reinforcing portion removing step, as shown in FIG. 11, the wafer consisting only of the device region W1 having the dicing tape T1 ′ attached to the surface. The W ′ dicing tape T1 is held on the holding table 30.

(7) Division Step Next, imaging by the imaging means 33 is performed, and a street to be cut is detected through the vacuum region 300 and the dicing tape T1 ′ formed of glass. Then, as shown in FIG. 12, the cutting table G that penetrates the front and back is sequentially formed by cutting the cutting blade 341 that rotates at high speed while moving the holding table 30 and the cutting means 34 in the horizontal direction into the detected street. I will do it. Further, when the streets in the same direction are all cut and then the holding table 30 is rotated 90 degrees and the same cutting is performed, the streets are cut vertically and horizontally and divided into individual devices. All devices are then transported together by a suction pad for suctioning the entire wafer surface. If the imaging means 33 is not disposed below the holding table 30, or if the vacuum region 300 is formed of metal or the like and does not transmit light, an infrared imaging means is disposed above the holding table 30. The streets on the front side can be detected from the back side of the wafer W.

(8) Dicing Tape Replacement Process As shown in FIG. 13, the dicing tape T2 may be adhered to the grinding surface W3 of the wafer W ′ consisting only of the device region D1 after the ring-shaped reinforcing portion removing process. Good. The wafer W ′ is accommodated in the opening F20 of the annular frame F2, and the dicing tape T2 is attached to the grinding surface W3 and the frame F2 of the wafer W ′, thereby closing the opening F20 with the dicing tape T2, and the dicing tape. The wafer W ′ is supported by the frame F2 through T2. That is, in this state, the dicing tape T1 is attached to the surface Wa of the wafer W ′, and the dicing tape T2 is attached to the grinding surface W3 of the wafer W ′. And as shown in FIG. 14, the front and back are reversed and the dicing tape T1 is peeled from the surface Wa side of the wafer '. In this way, the dicing tape T2 is adhered to the grinding surface W3 of the wafer W ′, and the wafer W ′ is supported by the frame F via the dicing tape T2.

(9) Dividing Step Next, in the state where the dicing tape T1 is peeled off from the surface Wa of the wafer W ′ and the dicing tape T2 is attached to the grinding surface W3 by the dicing tape attaching step, the dicing tape T2 is held on the holding table 30. As shown in FIG. 15, a cutting blade 341 is cut into the street of the wafer W ′ to form a cutting groove G penetrating the front and back of the wafer W ′. However, the dicing tape T2 is not penetrated. Further, when the streets in the same direction are all cut and then the holding table 30 is rotated 90 degrees and the same cutting is performed, the streets are cut vertically and horizontally and divided into individual devices. All devices are then transported together by a suction pad for wafer front side suction.

  As described above, each device can be formed by dividing the wafer W ′ including only the device region W1 after removing the ring-shaped reinforcing portion W4 without damaging the ring-shaped reinforcing portion W4.

W, W ′: Wafer Wa: Front surface W1: Device region W2: Peripheral surplus region D: Device S: Street W12: Boundary portion Wb: Back surface W3: Grinding surface W4: Ring-shaped reinforcing portion W5: Ring end materials T1, T1 ′ T2: Dicing tape F1, F2: Frame F10, F20: Opening portion 1: Protection member 2: Grinding device 20: Holding table 21: Grinding portion 22: Rotating shaft 23: Wheel 24: Grinding wheel portion 3: Cutting device 30: Holding Table 300: Vacuum region 301: Escape groove 302: Frame support unit 31: Rotating shaft 32: Rotation drive unit 33: Imaging unit 34: Cutting unit 340: Spindle 341: Cutting blade 342: Cutting water nozzle

Claims (4)

For a wafer having a device region in which a plurality of devices are formed and a peripheral surplus region surrounding the device region formed on the surface, the back side of the device region is ground on the back side of the wafer, and the back side of the peripheral surplus region Including a step of forming a ring-shaped reinforcing portion, a wafer processing method of removing the ring-shaped reinforcing portion after performing predetermined processing on the wafer on which the ring-shaped reinforcing portion is formed,
A frame arrangement in which a wafer is accommodated in the opening of a frame having an opening for accommodating the wafer, a dicing tape is adhered to the surface of the wafer and the frame, and the wafer is supported on the frame via the dicing tape. Process,
The wafer supported by the frame is held on a holding table, and the boundary between the ring-shaped reinforcing portion and the device region is cut together with the dicing tape by a cutting blade to separate the device region and the ring-shaped reinforcing portion. A ring-shaped reinforcing part separating step,
Processing of a wafer comprising at least a ring-shaped reinforcing portion removing step of removing the ring-shaped reinforcing portion by removing the ring-shaped reinforcing portion supported by the frame via the dicing tape from the holding table together with the frame. Method. In the ring-shaped reinforcing portion separating step, an annular relief groove for releasing the cutting blade of the cutting blade is formed in the holding table at a position corresponding to the boundary portion between the ring-shaped reinforcing portion and the device region,
Before cutting the boundary between the ring-shaped reinforcing portion and the device region together with the dicing tape to separate the device region and the ring-shaped reinforcing portion, avoid the escape groove and cut the inside of the boundary with a cutting blade. The wafer processing method according to claim 1, wherein the ring-shaped reinforcing portion and the device region are separated by cutting and cutting the cutting blade without penetrating the dicing tape. The wafer processing method according to claim 1, wherein after the ring-shaped reinforcing portion removing step, a dividing step of dividing a wafer consisting only of device regions held on the holding table into individual devices is performed. After the ring-shaped reinforcing portion removing step, the wafer having only the device region is accommodated in the opening portion of the frame having the opening portion for accommodating the wafer having only the device region held on the holding table, and the back surface of the wafer and A dicing tape is attached to the frame, and the wafer is supported on the frame through the dicing tape.
The wafer processing method according to claim 1, wherein a dividing step of dividing the wafer into individual devices is performed.

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