JP2024065409A - Wafer Processing Method - Google Patents

Abstract

[Problem] To provide a wafer processing method capable of reducing chipping. [Solution] A planarization step for planarizing a protective member 113 is carried out before the holding step and the machined groove forming step. Therefore, when the protective member 113 side of the wafer 100 is held by the holding table 41 in the holding step, the protective member 113 can be brought into close contact with the holding table 41. This makes it possible to prevent the wafer 100 from slightly floating from the holding table 41. Therefore, when the wafer 100 comes into contact with the cutting blade 32 in the machined groove forming step, the wafer 100 can be prevented from moving. This makes it possible to prevent chipping from occurring on the wafer 100. [Selected Figure] Figure 5

Description

The present invention relates to a wafer processing method.

There is a process in which a protective member is formed on the front side of the wafer, where the pattern is formed, and the protective member side of the wafer is held by a holding table, and the wafer is processed from the back side.

JP 2020-157387 A

In the above processing process, if the step in the pattern is large, a step may also be formed in the protective material, causing the wafer to partially float slightly above the holding table. If dividing grooves are formed from the back side in this state, the wafer may move, causing large chipping on the pattern surface.

The object of the present invention is to provide a wafer processing method that can reduce chipping.

The wafer processing method of this grinding device (this processing method) is a wafer processing method in which a wafer having a plurality of planned division lines and device regions partitioned by the planned division lines formed on its surface is processed along the planned division lines, and is characterized by comprising a protective member forming step of forming a protective member on the surface of the wafer, a planarizing step of planarizing the protective member, a holding step of holding the protective member side of the wafer by a holding table after the planarizing step and exposing the back side of the wafer, and a processing groove forming step of forming a processing groove in the wafer from the back side after the holding step is performed.

In addition, in this processing method, the processing groove forming step may include dividing the wafer to produce multiple chips.

In addition, in this processing method, the planarizing step may include grinding the protective member with a grinding wheel.

In addition, in this processing method, the planarizing step may include cutting the protective member with a bit cutting unit having a bit tool.

In addition, in this processing method, the holding table that holds the wafer in the processing groove forming step may be formed as a transparent member, and the processing groove forming step may include detecting the planned division line by imaging the wafer with an imaging unit through the holding table.

In addition, in this processing method, the protective member forming step may include supporting the wafer in the opening of the frame with the protective member.

In this processing method, a planarization step is carried out before the holding step and the machining groove forming step to planarize the surface of the protective member. Therefore, when the protective member side of the wafer is held by the holding table in the holding step, the protective member can be tightly attached to the holding table. This makes it possible to prevent the wafer from floating slightly from the holding table. Therefore, it is possible to prevent the wafer from moving in the machining groove forming step. This makes it possible to prevent chipping of the wafer.

FIG. 1A is a perspective view showing a wafer, and FIG. 1B is a perspective view showing a work set including the wafer. FIG. 1 is a block diagram showing a processing system. FIG. 2 is an explanatory diagram showing a work set including a wafer. FIG. 13 is an explanatory diagram showing a planarization step. FIG. 11 is an explanatory diagram showing a processing groove forming step. FIG. 11 is an explanatory diagram showing another example of the planarizing step.

In the chip spacing forming method according to this embodiment, a wafer 100 as shown in FIG. 1(a) is used as the workpiece. The wafer 100 is circular and has a front surface 101 and a back surface 102. A plurality of first planned division lines 103 extending in a first direction and a plurality of second planned division lines 104 extending in a second direction perpendicular to the first direction are formed on the front surface 101 of the wafer 100. In addition, device regions partitioned by the first planned division lines 103 and the second planned division lines 104 are formed on the front surface 101 of the wafer 100, and devices 105 are formed in each device region.

In this embodiment, the wafer 100 is handled in the state of a work set 110, as shown in FIG. 1(b). The work set 110 is formed by integrating an annular frame 111 having an opening 112 capable of accommodating the wafer 100 with the wafer 100 positioned in the opening 112 of the frame 111 using a protective member 113 so that the back surface 102 is exposed.

In this embodiment, the wafer 100 is processed in the processing system 1 shown in FIG. 2 while in this state of the work set 110.

The processing system 1 shown in FIG. 2 is a system that processes a wafer 100, and includes a work set forming device 2 that uses the wafer 100 to form a work set 110, a grinding device 4 that grinds the wafer 100, a cutting device 5 that cuts the wafer 100, a transport device 6 that transports the wafer 100 between these devices, and a control unit 7 that controls these devices.

The control unit 7 includes a CPU that performs calculations according to a control program, and a storage medium such as a memory. The control unit 7 controls each component of the processing system 1 to process the wafer 100.

The following describes a method for processing the wafer 100 according to this embodiment, which is controlled by the control unit 7. This processing method is a method for processing the wafer 100, which has a plurality of planned division lines 103 and 104 on the surface 101 and device regions defined by the planned division lines 103 and 104, along the planned division lines 103 and 104.

[Protective member forming step]
First, a protective member forming step is performed. In this protective member forming step, a protective member 113 is formed on the front surface 101 of the wafer 100. That is, in this step, the control unit 7 uses the work set forming device 2 to support the wafer 100 in the opening 112 of the frame 111 with the protective member 113, thereby forming the work set 110 shown in FIG. 1B.

Specifically, first, the control unit 7 positions the wafer 100 inside the circular opening 112 of the frame 111 shown in FIG. 1(b). Then, the control unit 7 adheres the protective member 113 to the surface 101 of the wafer 100 and the frame 111 from the surface 101 side of the wafer 100 using an adhesion roller or the like (not shown). After that, the protective member 113 is cut on the frame 111. This forms the work set 110.

In this embodiment, the protective member 113 is a tape in which an adhesive layer (sticky layer) and a base layer are laminated, and the adhesive layer of the protective member 113 is attached to the surface 101 of the wafer 100 and the frame 111.

The protective member 113 may be a sheet made of a thermoplastic resin without a glue layer. In this case, the protective member 113 is preferably, for example, a polyolefin sheet, a polyethylene sheet, a polypropylene sheet, or a polystyrene sheet. In this case, the protective member 113 is attached (fixed) to the frame 111 and the surface 101 of the wafer 100 by thermocompression bonding. The protective member 113 may be formed by applying an ultraviolet-curing or thermosetting liquid resin to the wafer 100 and curing it, or may be formed by overlapping a liquid resin and a tape, or a liquid resin and a sheet.

By this protective member formation step, as shown in FIG. 1(b) and FIG. 3, a work set 110 including a wafer 100, a frame 111, and a protective member 113 is formed. In this embodiment, the device 105 formed on the wafer 100 includes a pattern with a large step such as a TEG (test elementary group). Therefore, as shown in FIG. 3, this step is also transferred to the protective member 113, and unevenness 114 is formed on the protective member 113.

[Planarization step]
Next, the work set 110 shown in Fig. 3 is transferred to the grinding device 4 shown in Fig. 2 by the transfer device 6 or an operator. Then, in the grinding device 4, a planarization step is performed to planarize the protective member 113 formed on the wafer 100.

As shown in FIG. 4, the grinding device 4 has a grinding mechanism 10 equipped with a grinding wheel 14, and a first holding part 20 that holds a work set 110.

The grinding mechanism 10 includes a spindle 11, a spindle motor 12 that rotates the spindle 11 around a rotation axis 201 in the Z-axis direction, a mount 13 that is disposed at the lower end of the spindle 11, and a grinding wheel 14 that is attached to the mount 13. The grinding wheel 14 includes a wheel base 141 and a plurality of grinding stones 140 that are approximately rectangular parallelepipeds and arranged in a ring shape on the lower surface of the wheel base 141.

The grinding mechanism 10 is connected to a lifting mechanism (not shown) and can be raised and lowered in the Z-axis direction by this lifting mechanism.

The first holding unit 20 has a chuck table 21 that holds the wafer 100, and a number of clamp units 24 provided around the periphery of the chuck table 21.

The chuck table 21 is a member for holding the wafer 100 during the planarization step, and has a holding surface 22 made of a porous material. This holding surface 22 can be connected to a suction source (not shown). The chuck table 21 uses this holding surface 22 to suction and hold the wafer 100 in the work set 110. A number of (for example, four) clamping parts 24 clamp and fix the frame 111 around the wafer 100 held on the chuck table 21.

The chuck table 21 is connected to a rotation mechanism (not shown) and can rotate around a rotation axis 202 in the Z-axis direction that passes through the center of the holding surface 22.

In the planarization step, the work set 110 including the wafer 100 is placed on the chuck table 21 of the first holding unit 20 in the grinding device 4 with the protective member 113 facing upward.

Then, the control unit 7 supports the frame 111 of the work set 110 with the clamp unit 24 of the first holding unit 20, and suction-holds the back surface 102 of the wafer 100 with the holding surface 22 of the chuck table 21.

Next, the control unit 7 rotates the chuck table 21 around the rotation axis 202 in the Z-axis direction using a rotation mechanism (not shown), thereby rotating the work set 110 including the wafer 100 held by the chuck table 21 and the clamp unit 24.

The control unit 7 also rotates the grinding wheel 14 around the rotation shaft 201 using the spindle motor 12. In this state, the control unit 7 lowers the grinding mechanism 10 in the -Z direction using a lifting mechanism (not shown). This causes the grinding stone 140 of the grinding wheel 14 to come into contact with the protective member 113 formed on the front surface 101 side of the wafer 100 in the work set 110, grinding the protective member 113.

In this way, the planarization step includes grinding the protective member 113 with a grinding wheel 14 including a grinding stone 140. By grinding the protective member 113, the unevenness 114 of the protective member 113 shown in FIG. 3 is removed, and the protective member 113 is planarized.

[Holding step]
After such a planarization step is performed, the wafer 100 is removed from the chuck table 21 that held the wafer 100 in the planarization step, and a holding step is performed in which the wafer 100 is held by a holding table used in the machining groove forming step. That is, the work set 110 including the planarized protective member 113 is transported to the cutting device 5 shown in Fig. 2. Then, in the cutting device 5, a holding step is performed in which the protective member 113 side of the wafer 100 is held by a holding table, and the back surface 102 side of the wafer 100 is exposed.

As shown in FIG. 5, the cutting device 5 has a cutting mechanism 30 that cuts the wafer 100, a second holding part 40 that holds the work set 110, and an imaging mechanism 50 that images the wafer 100.

The cutting mechanism 30 includes a blade spindle 31 having a horizontal rotation axis 301, and a cutting blade 32 that rotates together with the blade spindle 31. The cutting mechanism 30 is connected to a moving mechanism (not shown), and can be moved in the Z-axis direction by this moving mechanism.

The second holding unit 40 has a holding table 41 that holds the wafer 100, and a number of clamp units 44 provided around the holding table 41.

The holding table 41 is a member for holding the wafer 100, and has a holding surface 42 on which the wafer 100 is placed. In this embodiment, the holding table 41 is made of a transparent material and is formed as a transparent member. A plurality of (for example, four) clamp parts 44 clamp and fix a frame 111 around the wafer 100 placed on the holding table 41. The second holding part 40 is connected to a moving mechanism (not shown), and can be moved in the horizontal direction (X-axis direction and Y-axis direction) by this moving mechanism.
The holding table 41 may have a configuration in which the holding surface 42 holds the wafer 100 by suction, so long as an image can be captured by the imaging mechanism 50 described later.

The imaging mechanism 50 is disposed below the holding table 41 and has an imaging unit 51 consisting of a camera etc., and an imaging unit moving mechanism 52 that moves the imaging unit 51 in the horizontal direction. The imaging unit 51 is capable of imaging the wafer 100 placed on the holding surface 42 of the holding table 41 via the holding table 41.

In the holding step, the wafer 100 of the work set 110 is placed on the holding surface 42 of the holding table 41 by the transport device 6 or an operator with the back surface 102 facing upward. Furthermore, the control unit 7 supports the frame 111 of the work set 110 by the clamp unit 44 of the second holding unit 40. As a result, the protective member 113 side of the wafer 100 is held by the holding table 41, and the work set 110 is held by the second holding unit 40 so that the back surface 102 side of the wafer 100 is exposed.

[Groove formation step]
After the holding step, a groove forming step is performed in which a groove is formed in the wafer 100 held on the holding table 41 in the holding step from the back surface 102 side.

In this step, first, the control unit 7 controls the imaging mechanism 50 to have the imaging unit 51 capture an image of the wafer 100 from below the holding table 41, through the holding table 41 and the protective member 113, thereby detecting the first planned division line 103 and the second planned division line 104 (see FIG. 1(a)) formed on the surface 101 of the wafer 100.

As described above, the wafer 100 is held by the holding table 41 so that the protective member 113 side (i.e., the surface 101 side) faces downward. Therefore, the imaging unit 51 arranged below the holding table 41 can image the surface 101 through the holding table 41 and the protective member 113. The control unit 7 can then easily detect the positions of the first planned division line 103 and the second planned division line 104 on the wafer 100 based on the imaging results.

Next, the control unit 7 adjusts the horizontal position and orientation of the second holding unit 40 holding the wafer 100, thereby aligning one first planned division line 103 with the position and orientation of the cutting blade 32 of the cutting mechanism 30. In this state, the control unit 7 lowers the cutting blade 32 while rotating the cutting blade 32 with the blade spindle 31, causing the cutting blade 32 to cut into the first planned division line 103. In this embodiment, the cutting blade 32 is lowered to a position where the wafer 100 can be cut by the cutting blade 32.

The control unit 7 then moves the second holding unit 40 in the direction in which the first planned division line 103 extends. This causes a machining groove 120 to be formed along the first planned division line 103, with a depth sufficient to cut the wafer 100, and the wafer 100 is cut.

In this manner, the control unit 7 cuts the wafer 100 along all of the first division lines 103 and the second division lines 104 by forming grooves 120 along these lines. This causes the wafer 100 to be divided into a plurality of chips 106. In this manner, the groove formation step includes dividing the wafer 100 to manufacture a plurality of chips 106. Each chip 106 has a device 105 (see FIG. 1(a)).

As described above, in this embodiment, a planarization step for planarizing the protective member 113 is performed before the holding step and the machining groove forming step. Therefore, in the holding step, when the protective member 113 side of the wafer 100 is held by the holding table 41, the protective member 113 can be brought into close contact with the holding table 41. This makes it possible to prevent the wafer 100 from floating slightly from the holding table 41. Therefore, in the machining groove forming step, it is possible to prevent the wafer 100 from moving when the wafer 100 comes into contact with the cutting blade 32. This makes it possible to prevent chipping of the wafer 100.

In addition, in the groove forming step, if the wafer 100 is divided to form multiple grooves 120, it becomes difficult to transport the wafer 100 without damaging it if the wafer 100 is held only by the protective member 113. Therefore, when forming the grooves 120 for dividing the wafer 100 in the groove forming step, it is preferable to perform the step with the protective member 113 fixed to the frame 111. Usually, the frame 111 is not used in the flattening step, but in this embodiment, the flattening step is performed in the work set 110, so that the series of steps of the holding step and the groove forming step can be performed using the same work set 110 without changing the work set 110. In addition, by performing alignment to detect the planned division lines 103 and 104 through the transparent holding surface 42 in the groove forming step, it is possible to perform processing from the back surface 102 side of the wafer 100 using the same work set 110 following the flattening step. Therefore, there is no need to remake the work set 110 in order to expose the front surface 101 side of the wafer 100 in the planarization step and the back surface 102 side of the wafer 100 in the groove formation step, and each step can be performed efficiently. In addition, by using the work set 110, handling of the wafer 100 (for example, holding, processing, and transporting the wafer 100) becomes easier.

In this embodiment, the planarization step is performed by the grinding device 4. In this regard, the processing system 1 may be provided with a bit cutting device 8 as shown in FIG. 6 instead of the grinding device 4, and the planarization step may be performed by the bit cutting device 8.

The bit cutting device 8 is configured to have a bit cutting unit 16 instead of the grinding mechanism 10 in the configuration of the grinding device 4 shown in FIG. 4. The bit cutting unit 16 is configured to have a bit wheel 17 instead of the grinding wheel 14 in the configuration of the grinding mechanism 10.

The cutting wheel 17 includes a wheel base 171 and a cutting tool 170 that is removably attached to the bottom of the wheel base 171. The cutting tool 170 includes, for example, a diamond in the cutting blade.

The bit cutting unit 16 is connected to a lifting mechanism (not shown) like the grinding mechanism 10, and can be raised and lowered in the Z-axis direction by this lifting mechanism.

Even in the planarization step using the cutting tool 8, the work set 110 including the wafer 100 is placed on the chuck table 21 of the first holding unit 20 in the cutting tool 8 with the protective member 113 facing upward.

Then, the control unit 7 supports the frame 111 of the work set 110 with the clamp unit 24 of the first holding unit 20, and suction-holds the back surface 102 of the wafer 100 with the holding surface 22 of the chuck table 21.

The control unit 7 then rotates the chuck table 21 around the rotation axis 202 in the Z-axis direction using a rotation mechanism (not shown) to rotate the work set 110. The control unit 7 also rotates the bite wheel 17 around the rotation axis 201 using the spindle motor 12 of the bite cutting unit 16. In this state, the control unit 7 lowers the bite cutting unit 16 in the -Z direction using a lifting mechanism (not shown). This causes the bite tool 170 of the bite wheel 17 to come into contact with the protective member 113 formed on the front surface 101 side of the wafer 100 in the work set 110, cutting the protective member 113.

Thus, this planarization step includes cutting the protective member 113 with the bit cutting unit 16 (bit wheel 17) having the bit tool 170. By cutting the protective member 113, the unevenness 114 of the protective member 113 shown in FIG. 3 is removed, and the protective member 113 is planarized.

In the planarization step using such a cutting tool 8, when the protective member 113 has a high viscosity, it is possible to more effectively remove the irregularities 114 of the protective member 113 than when the grinding device 4 is used.

In addition, in this embodiment, in the machining groove forming step, as shown in FIG. 5, the imaging unit 51 of the imaging mechanism 50 arranged below the holding table 41 captures an image of the surface 101 of the wafer 100 through the holding table 41 and the protective member 113 to detect the positions of the first planned division line 103 and the second planned division line 104 on the wafer 100.

In this regard, in the cutting device 5, the imaging mechanism 50 may be positioned above the wafer 100 in the work set 110 held by the second holding part 40. In this case, it is preferable that the imaging mechanism 50 has an IR camera using infrared rays as the imaging unit 51.

In this configuration, the front surface 101 of the wafer 100 is imaged from the back surface 102 side by the imaging unit 51, and the first planned division line 103 and the second planned division line 104 are detected through the wafer 100. Even with this configuration, the positions of the first planned division line 103 and the second planned division line 104 on the wafer 100 can be detected well.

In addition, in this embodiment, as shown in FIG. 5, in the groove forming step, grooves 120 are formed along the first planned division line 103 and the second planned division line 104 to a depth sufficient to cut the wafer 100, thereby cutting the wafer 100. In this regard, in the groove forming step, grooves 120 may be formed to a depth sufficient not to cut the wafer 100 (i.e., the wafer 100 may be half-cut).

In this case, after the groove forming step, tension can be applied to the protective member 113 to divide the wafer 100 along the groove 120 to form the chips 106. Alternatively, after the groove forming step, plasma etching can be performed on the wafer 100 to divide the wafer 100 along the groove 120 to form the chips 106.

In addition, in this embodiment, the machining groove forming step of forming the machining groove 120 in the wafer 100 is performed using a cutting device 5 having a cutting blade 32. In this regard, the machining groove forming step may be performed by ablation processing using a laser beam.

1: machining system, 2: work set forming device, 4: grinding device, 5: cutting device,
6: conveying device, 7: control unit, 8: bit cutting device,
10: grinding mechanism, 11: spindle, 12: spindle motor, 13: mount,
14: grinding wheel, 16: byte cutting unit, 17: byte wheel,
20: first holding portion, 21: chuck table, 22: holding surface, 24: clamp portion,
30: cutting mechanism, 31: blade spindle, 32: cutting blade,
40: second holding portion, 41: holding table, 42: holding surface, 44: clamp portion,
50: imaging mechanism, 51: imaging unit, 52: imaging unit moving mechanism,
100: wafer, 101: front surface, 102: back surface, 103: first division line,
104: second division line, 105: device, 106: chip,
110: work set, 111: frame, 112: opening, 113: protective member,
114: unevenness, 120: machining groove, 140: grinding wheel, 141: wheel base,
170: Bit tool, 171: Wheel base

Claims (6)

A wafer processing method for processing a wafer having a plurality of division lines and device regions defined by the division lines formed on a surface thereof along the division lines, the method comprising the steps of:
a protective member forming step of forming a protective member on the front surface of the wafer;
a planarizing step of planarizing the protective member;
a holding step of holding the protective member side of the wafer by a holding table after the planarization step is performed, and exposing the back side of the wafer;
a groove forming step of forming a groove in the wafer from the back surface side after the holding step is performed;
The present invention is characterized in that it comprises
Wafer processing method. The method is characterized in that the process includes dividing the wafer into a plurality of chips, in the process of forming the processed groove.
The wafer processing method according to claim 1 . The flattening step includes grinding the protective member with a grinding wheel.
The wafer processing method according to claim 1 . The planarizing step includes cutting the protective member by a bit cutting unit having a bit tool.
The wafer processing method according to claim 1 . The holding table is formed as a transparent member,
The machining groove forming step includes detecting the planned dividing line by imaging the wafer with an imaging unit via the holding table.
The wafer processing method according to claim 1 . The step of forming the protective member includes supporting the wafer in the opening of the frame by the protective member.
The wafer processing method according to claim 1 .

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