Segmentation method and segmentation device

Abstract

The present invention provides a dividing method and a dividing apparatus capable of forming a dividing groove with a desired width. The dividing method is a method for dividing a workpiece that has a modified layer formed along a dividing predetermined line and is pasted on an extension sheet, and the dividing method includes the following steps: a dividing step of expanding the extension sheet and dividing the workpiece along the modified layer to form a dividing groove along the dividing predetermined line; an expansion release step of releasing the expansion of the extension sheet after the dividing step is performed; and a groove width adjustment step of expanding the extension sheet after the expansion release step is performed to form the dividing groove into a desired width.

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for dividing a workpiece that is formed with a division start point along a division predetermined line and is pasted on an expansion sheet. Background Art

[0002] When dividing a workpiece such as a wafer into individual device chips along a division predetermined line, a division method and a division apparatus that expand (stretch) an expansion sheet pasted on the workpiece formed with a division start point along the division predetermined line are used (for example, refer to Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2010-206136

[0004] In the case of dividing by expanding the expansion sheet as in the division method and the division apparatus shown in Patent Document 1, since the states of the division start points are uneven, the timing of cracking deviates. Moreover, a wider division groove is formed in a portion where cracking occurs earlier, and a narrower division groove is formed in a portion where cracking occurs later. Therefore, in the case of dividing by expanding the expansion sheet as in the division method and the division apparatus shown in Patent Document 1, the width of the division groove deviates.

[0005] When a division groove having a sufficient width is not formed between chips, adjacent chips may come into contact with each other during processing and damage the chips. It is desired to form a division groove having a desired width wider than the width at which contact may occur. Summary of the Invention

[0006] Accordingly, an object of the present invention is to provide a division method and a division apparatus capable of forming a division groove having a desired width.

[0007] According to one aspect of the present invention, there is provided a division method, which is a division method of a workpiece that is formed with a division start point along a division predetermined line and is pasted on an expansion sheet, and the division method includes the following steps: a division step of expanding the expansion sheet to divide the workpiece along the division start point to form a division groove along the division predetermined line; an expansion release step of releasing the expansion of the expansion sheet after the division step is performed; and a groove width adjustment step of expanding the expansion sheet after the expansion release step is performed to form the division groove into a desired width.

[0008] Preferably, in the division step, the expansion sheet is expanded at a first speed, and in the groove width adjustment step, the expansion sheet is expanded at a second speed lower than the first speed.

[0009] Preferably, the division method further includes the following fixing step: after the groove width adjustment step is performed, the division groove is fixed according to the desired width.

[0010] Preferably, the workpiece is formed to be mounted on a ring-shaped frame having an opening by means of the extension piece and disposed within the opening. In the dividing step and the slot width adjusting step, the extension piece is extended by pressing the extension piece between the outer periphery of the workpiece and the inner periphery of the ring-shaped frame while the ring-shaped frame is fixed. In the fixing step, the workpiece in which the dividing slot is formed to the desired width through the slot width adjusting step is attracted and held by the suction holding member with the extension piece interposed therebetween, and the extension piece between the outer periphery of the workpiece and the inner periphery of the ring-shaped frame is heated to contract the extension piece, thereby removing the slack generated by the extension.

[0011] Preferably, in the fixing step, the ring-shaped frame is adhered to the extension piece in a state where the extension piece is extended through the slot width adjusting step in such a manner that the workpiece is disposed within the opening of the ring-shaped frame having the opening.

[0012] According to another aspect of the present invention, there is provided a dividing device that implements the dividing method, wherein the dividing device includes: an extension unit that extends the extension piece; and a controller that controls the extension unit, and the controller includes: a dividing control unit that extends the extension piece and divides the workpiece along the dividing starting point to form a dividing slot along the dividing predetermined line; an extension releasing unit that releases the extension of the extension piece after the workpiece is divided; and a slot width adjusting unit that extends the extension piece after the extension of the extension piece is released to form the dividing slot into a desired width.

[0013] The present invention has the effect of being able to form a dividing slot with a desired width. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a perspective view showing a structural example of the dividing device according to the first embodiment.

[0015] Figure 2 is Figure 1 a perspective view of the workpiece to be processed by the dividing device shown.

[0016] Figure 3 is a flowchart showing the process of the dividing method according to the first embodiment.

[0017] Figure 4 is a side view showing, in a partial cross-section, a state where the frame is placed on the upper surface of the frame mounting plate of the frame fixing portion in the holding step of the dividing method shown in Figure 3 is a side view showing, in a partial cross-section, a state where the frame is placed on the upper surface of the frame mounting plate of the frame fixing portion in the holding step of the dividing method shown in

[0018] Figure 5 is a side view showing, in a partial cross-section, a state where the frame is placed on the upper surface of the frame mounting plate of the frame fixing portion in the holding step of the dividing method shown in Figure 3Side view of the state where the frame fixing part holds and fixes the frame in the holding step of the shown splitting method.

[0019] Figure 6 is shown in a partial cross-section Figure 3 Side view of the splitting step of the shown splitting method.

[0020] Figure 7 is Figure 6 Top view of the main part of the workpiece shown.

[0021] Figure 8 is shown in a partial cross-section Figure 3 Side view of the expansion release step of the shown splitting method.

[0022] Figure 9 is Figure 8 Top view of the main part of the workpiece shown.

[0023] Figure 10 is shown in a partial cross-section Figure 3 Side view of the groove width adjustment step of the shown splitting method.

[0024] Figure 11 is Figure 10 Top view of the main part of the workpiece shown.

[0025] Figure 12 is shown in a partial cross-section Figure 3 Side view of the fixing step of the shown splitting method.

[0026] Figure 13 Isometric view showing a structural example of the splitting device according to the second embodiment.

[0027] Figure 14 Top view schematically showing the holding step of the splitting method according to the second embodiment.

[0028] Figure 15 Top view schematically showing the splitting step of the splitting method according to the second embodiment.

[0029] Figure 16 Top view of the main part of the workpiece in the splitting step of the splitting method according to the second embodiment.

[0030] Figure 17 Top view of the main part of the workpiece in the expansion release step of the splitting method according to the second embodiment.

[0031] Figure 18 Top view of the main part of the workpiece in the groove width adjustment step of the splitting method according to the second embodiment.

[0032] Figure 19 It is a plan view schematically showing the fixing step of the splitting method of the second embodiment.

[0033] Label Explanation

[0034] 1, 1-2: Splitting device; 20: Expansion unit; 40: Chuck table (suction holding member); 50: Control unit (controller); 51: Splitting control section; 52: Expansion release section; 53: Groove width adjustment section; 133-1: First moving unit (expansion unit); 133-2: Second moving unit (expansion unit); 133-3: Third moving unit (expansion unit); 133-4: Fourth moving unit (expansion unit); 200: Workpiece; 203: Splitting predetermined line; 206: Modified layer (splitting starting point); 208: Expansion sheet; 209: Frame; 210: Splitting groove; 211: Slack; 212: Opening; 301: First speed; 302: Second speed; 1002: Splitting step; 1003: Expansion release step; 1004: Groove width adjustment step; 1005: Fixing step. Detailed Embodiment

[0035] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the content described in the following embodiments. In addition, among the structural elements described below, there are substantially the same structural elements that can be easily conceived by those skilled in the art. Furthermore, the structures described below can be appropriately combined. In addition, various omissions, substitutions, or changes of the structure can be made without departing from the gist of the present invention.

[0036] 〔First Embodiment〕

[0037] The splitting device according to the first embodiment of the present invention will be described with reference to the drawings. Figure 1 It is a perspective view showing a structural example of the splitting device of the first embodiment. Figure 2 It is Figure 1 A perspective view of the workpiece which is the processing object of the shown splitting device.

[0038] Of the first embodiment Figure 1 The shown splitting device 1 is a splitting device that splits Figure 2 The shown workpiece 200 into individual device chips 201. The workpiece 200 that is the processing object of the splitting device 1 is a wafer such as a circular semiconductor wafer or an optical device wafer having a substrate 202 such as silicon, sapphire, or gallium arsenide.

[0039] As Figure 2As shown, in the workpiece 200, devices 204 are formed in a plurality of regions defined by a plurality of division predetermined lines 203 set in a grid pattern on the front surface 205 of the substrate 202. The devices 204 are, for example, integrated circuits such as ICs (Integrated Circuits) or LSIs (Large Scale Integration), or image sensors such as CCDs (Charge Coupled Devices) or CMOSs (Complementary Metal Oxide Semiconductors).

[0040] In the first embodiment, the workpiece 200 is divided along the division predetermined lines 203 for each device 204, and thus divided into individual device chips 201. The device chip 201 has a part of the substrate 202 and the device 204 on the substrate 202.

[0041] By Figure 1 shown, in the workpiece 200 divided into individual device chips 201 by the dividing device 1, a modified layer 206 serving as a division starting point is formed along the division predetermined line 203 inside the substrate 202. The modified layer 206 is formed by setting the focal point of a laser beam having a wavelength (1064 nm in the embodiment) that is transmissive to the substrate 202 of the workpiece 200 inside the substrate 202 of the workpiece 200 and irradiating it along the division predetermined line 203 from the back surface 207 side on the back side of the front surface 205. In addition, the modified layer 206 refers to a region where the density, refractive index, mechanical strength, and other physical properties are in a state different from those of the surrounding area, and examples thereof include a molten treatment region, a crack region, an insulation breakdown region, a refractive index change region, and a region in which these regions are mixed. In addition, the mechanical strength of the modified layer 206 is lower than that of other parts of the workpiece 200.

[0042] In addition, in the first embodiment, an expansion sheet 208 having a diameter larger than that of the workpiece 200 is adhered to the back surface 207 side of the workpiece 200, and a ring-shaped frame 209 is adhered to the outer peripheral edge of the expansion sheet 208, and the workpiece 200 is supported within the opening 212 of the frame 209. In the first embodiment, as Figure 2 shown, the workpiece 200 is formed in a state of being mounted on the frame 209 having the opening 212 by means of the expansion sheet 208 and being disposed within the opening 212 of the frame 209.

[0043] In the first embodiment, a frame 209 is attached to the outer peripheral edge of the extension sheet 208 attached to the back surface 207 side of the workpiece 200. However, the present invention is not limited thereto. For example, a disk-shaped DAF (die attach film) may be attached between the back surface 207 of the workpiece 200 and the extension sheet 208. In addition, in the present invention, the workpiece 200 to which the DAF is attached may also be used. Further, the outer diameter of the extension sheet 208 is formed to be larger than the outer diameter of the workpiece 200, and the extension sheet 208 has elasticity and is made of a synthetic resin that shrinks when heated.

[0044] The dicing device 1 of the first embodiment includes a chamber (not shown), a frame fixing unit 10, an extension unit 20, a heating unit 30 as a fixing unit, a chuck table 40 as a suction holding member, and a control unit 50 as a controller.

[0045] The chamber is formed in a box shape with an open upper portion. The chamber houses the frame mounting plate 11 of the frame fixing unit 10, the extension unit 20, and the chuck table 40.

[0046] The frame fixing unit 10 holds and fixes the frame 209. The frame fixing unit 10 includes a frame mounting plate 11 and a frame pressing plate 12.

[0047] The frame mounting plate 11 is provided with an opening 13 having a circular planar shape, and the upper surface 18 is formed in a plate shape that is parallel to the horizontal direction and flat. The four corners of the frame mounting plate 11 are supported by the rods 16 of the lifting cylinders 15. The inner diameter of the opening 13 of the frame mounting plate 11 is formed to be equal to the inner diameter of the frame 209. The frame mounting plate 11 mounts the frame 209 that supports the workpiece 200 by a transfer unit (not shown) on the upper surface 18.

[0048] The frame pressing plate 12 is formed in a plate shape having a planar shape larger than that of the frame mounting plate 11. The frame pressing plate 12 is provided with a circular opening 17 having the same size as the opening 13 at the center. The frame pressing plate 12 is fixed in the chamber, and the opening 17 is disposed at a position coaxial with the opening 13 of the frame mounting plate 11. The frame fixing unit 10 holds and fixes the frame 209 by sandwiching it between the frame mounting plate 11 that is lifted by the lifting cylinder 15 and the frame pressing plate 12.

[0049] The expansion unit 20 is a unit that lifts the expansion sheet 208 relative to the frame fixing unit 10 and moves the expansion sheet 208 a predetermined distance in a direction perpendicular to the front surface 205 of the workpiece 200 attached to the expansion sheet 208, thereby expanding the expansion sheet 208. The expansion unit 20 is also a unit that separates the workpiece 200, with the expansion sheet 208 attached to the back surface 207, into device chips 201 along the planned dividing lines 203 by expanding the expansion sheet 208 attached to the frame 209 held by the frame fixing unit 10.

[0050] The expansion unit 20 includes an expansion roller 21 and a roller lifting unit 22. The expansion roller 21 is cylindrical, with an outer diameter smaller than the inner diameter of the frame 209 placed on the upper surface 18 of the frame mounting plate 11. The expansion roller 21 has an inner diameter larger than the outer diameter of the workpiece 200 attached to the expansion sheet 208. The expansion roller 21 is positioned inside the opening 13 of the frame mounting plate 11 and coaxially with the opening 13 of the frame mounting plate 11 and the opening 17 of the frame pressing plate 12.

[0051] A roller member 23 ( Figure 4 The roller member 23 mitigates friction with the expansion piece 208 when the expansion roller 21 pushes up the expansion piece 208. In the first embodiment, the expansion roller 21 is raised and lowered by the roller raising and lowering unit 22.

[0052] The chuck table 40 attracts and holds the expanded expansion sheet 208, and attracts and holds the multiple device chips 201 separated into individual pieces via the expansion sheet 208 using the holding surface 41. The chuck table 40 is in the shape of a circular plate. The upper surface of the chuck table 40 is made of a porous material such as porous ceramics, and is in contact with the suction source 43 ( Figure 4 etc.) by connecting the retaining surface 41.

[0053] The chuck table 40 is arranged inside the expansion roller 21 and is arranged at a position coaxial with the openings 13, 17 and the expansion roller 21. The chuck table 40 places the back side 207 of the workpiece 200 on the holding surface 41 through the expansion piece 208. The chuck table 40 attracts the holding surface 41 with the suction source 43, thereby attracting and holding the back side 207 of the workpiece 200 on the holding surface 41. In addition, the chuck table 40 is arranged to be fixed to the expansion roller 21. Figure 4 The workbench lifting unit 42 ( Figure 4 etc.) to raise and lower the device.

[0054] The heating unit 30 heats the extension sheet 208 around the workpiece 200 to a temperature above a specified temperature. The heating unit 30 includes a disk-shaped unit body 31, a plurality of heat source parts 32 mounted on the unit body 31, a rotation unit 33, and a lifting unit 34.

[0055] The unit body 31 is disposed above the chuck table 40 and coaxially with the chuck table 40. The unit body 31 is rotatably provided by the rotation unit 33 around an axis parallel to the vertical direction. The unit body 31 is vertically movably provided by the lifting unit 34.

[0056] The heat source parts 32 are arranged at equal intervals in the circumferential direction at the outer edge part of the lower surface of the unit body 31. The heat source parts 32 are arranged at positions opposed to each other between the inner edge of the frame 209 of the extension sheet 208 held by the chuck table 40 and the frame fixing unit 10 and the outer edge of the workpiece 200 in the vertical direction. The heat source parts 32 heat the space between the inner edge of the frame 209 of the extension sheet 208 and the outer edge of the workpiece 200. In the embodiment, four heat source parts 32 are provided, but the present invention is not limited to four. The heat source part 32 is a component configured to heat the extension sheet 208 between the outer circumference of the workpiece 200 and the inner circumference of the frame 209 by irradiating infrared rays downward. For example, it is an infrared ceramic heater that is heated and emits infrared rays when a voltage is applied, but the present invention is not limited thereto.

[0057] The rotation unit 33 rotates the unit body 31 around the axis, causing the heat source parts 32 to move circumferentially along the outer circumference of the workpiece 200. The lifting unit 34 vertically moves the unit body 31, thereby adjusting the distance between the heat source parts 32 of the heating unit 30 and the extension sheet 208.

[0058] The control unit 80 controls the above-described structural elements of the dividing device 1, namely, the expanding unit 20, the heating unit 30, etc., so that the dividing device 1 performs a processing operation on the workpiece 200. The control unit 50 is, for example, a computer, which includes: an arithmetic processing device having a microprocessor such as a CPU (central processing unit); a storage device having a memory such as a ROM (read only memory) or a RAM (random access memory); and an input / output interface device. The control unit 80 is connected to a display unit (not shown) and an input unit (not shown). The display unit is composed of a liquid crystal display device or the like that displays the state and image of the processing operation, and the input unit is used when an operator registers processing content information or the like. The input unit is composed of at least one of an external input device such as a touch panel provided on the display unit and a keyboard.

[0059] In addition, asFigure 1 As shown in the figure, the control unit 50 includes a division control unit 51, an extension release unit 52, and a groove width adjustment unit 53.

[0060] The division control unit 51 holds and fixes the frame 209 supporting the workpiece 200 within the opening 212 to the frame fixing unit 10, and extends the extension sheet 208 adhered to the frame 209 held and fixed to the frame fixing unit 10 to divide the workpiece 200 along the modification layer 206, forming a division groove 210 along the division line 203 ( Figure 7 as shown in the figure). The extension release unit 52 releases the extension of the extension sheet 208 after the division control unit 51 divides the workpiece 200. After the extension release unit 52 releases the extension of the extension sheet 208, the groove width adjustment unit 53 extends the extension sheet 208 again to form the division groove 210 into a desired width. In addition, the functions of the division control unit 51, the extension release unit 52, and the groove width adjustment unit 53 are implemented by an arithmetic processing device executing a computer program stored in a storage device.

[0061] Next, the division method of the first embodiment will be described. Figure 3 FIG. is a flowchart showing the process of the division method of the first embodiment. The division method of the first embodiment is a method for dividing the workpiece 200 adhered to the extension sheet 208 into individual device chips 201. The division method of the first embodiment is implemented by <^ Figure 1 the division device 1 shown in the figure. That is, Figure 1 the division device 1 shown in the figure is a device for implementing the division method of the first embodiment.

[0062] As Figure 3 shown in the figure, the division method of the first embodiment includes a holding step 1001, a division step 1002, an extension release step 1003, a groove width adjustment step 1004, and a fixing step 1005.

[0063] (Holding step)

[0064] Figure 4 FIG. is a side view showing a state in which a frame is placed on the upper surface of a frame mounting plate of a frame fixing portion in the holding step of the division method shown in Figure 3 the figure, shown in a partial cross-section. Figure 5 FIG. is a side view showing a state in which the frame fixing portion holds and fixes the frame in the holding step of the division method shown in Figure 3 the figure, shown in a partial cross-section.

[0065] The holding step 1001 is a step in which the frame fixing unit 10 holds and fixes the frame 209 supporting the workpiece 200 within the opening 212. In the first embodiment, in the holding step 1001, the dividing control unit 51 of the control unit 50 of the dividing device 1 controls the lifting cylinder 15, the roller lifting unit 22, and the table lifting unit 42 to lower the frame placement plate 11, the extension roller 21, and the chuck table 40, controls the lifting unit 34 to raise the unit main body 31 of the heating unit 30, and stops the suction source 43 and the heat source unit 32. In the first embodiment, in the holding step 1001, as Figure 4 shown, the dividing device 1 places the frame 209 supporting the workpiece 200 within the opening 212 on the upper surface 18 of the frame placement plate 11 through a conveying unit (not shown).

[0066] In the first embodiment, in the holding step 1001, the dividing control unit 51 of the control unit 50 of the dividing device 1 controls the lifting cylinder 15 to raise the frame placement plate 11. As Figure 5 shown, the frame 209 is sandwiched between the frame placement plate 11 and the frame pressing plate 12, and the frame fixing unit 10 holds and fixes the frame 209. The dividing method proceeds to the dividing step 1002.

[0067] (Dividing step)

[0068] Figure 6 is a side view showing the dividing step of the dividing method shown in a partial cross-section. Figure 3 As shown. Figure 7 It is Figure 6 a top view of the main part of the workpiece shown. The dividing step 1002 is a step of expanding the extension piece 208 and dividing the workpiece 200 along the modified layer 206 to form a dividing groove 210 along the dividing predetermined line 203 on the workpiece 200.

[0069] In the first embodiment, in the dividing step 1002, the dividing control unit 51 of the control unit 50 of the dividing device 1 controls the roller lifting unit 22 to raise the extension roller 21 so that the roller member 23 is located above the upper surface 18 of the frame placement plate 11. Then, as Figure 6 shown, after the roller member 23 mounted on the upper end of the extension roller 21 abuts against the extension piece 208 between the outer periphery of the workpiece 200 and the inner periphery of the frame 209, it pushes the extension piece 208 upward, and the extension piece 208 expands in the plane direction. In the dividing step 1002, as a result of the expansion, a radial tensile force acts on the extension piece 208.

[0070] Thus, when a tensile force acts radially on the extension sheet 208 adhered to the back surface 207 side of the substrate 202 of the workpiece 200, since the workpiece 200 is formed with a modified layer 206 along the division predetermination line 203, it is divided into individual devices 204 starting from the modified layer 206, as Figure 7 shown, and is singulated into individual device chips 201, forming a division groove 210 along the division predetermination line 203. In addition, since the modified layer 206 is formed unevenly, during the division step 1002, when the extension sheet 208 is extended, the timing of fracture deviates. That is, in the division step 1002, there is almost no case where all the modified layers 206 fracture simultaneously. Therefore, as Figure 7 shown, the width of the division groove 210 after the division step 1002 deviates. The division method proceeds to the extension release step 1003.

[0071] (Extension release step)

[0072] Figure 8 is a side view showing the extension release step of the division method shown in Figure 3 by a partial cross-section. Figure 9 is Figure 8 a top view of the main part of the workpiece shown. The extension release step 1003 is a step of releasing the extension of the extension sheet 208 after the division step 1002 has been carried out.

[0073] In the first embodiment, in the extension release step 1003, the extension release unit 52 of the control unit 50 of the division device 1 controls the lifting unit 22 for the drum to lower the extension drum 21. Then, as Figure 8 shown, the roller member 23 mounted on the upper end of the extension drum 21 separates from the extension sheet 208 between the outer periphery of the workpiece 200 and the inner periphery of the frame 209, and no longer presses the extension sheet 208 upward, thereby releasing the extension of the extension sheet 208 in the plane direction. Then, as Figure 9 shown, the width of the division groove 210 is reduced compared to the width after the division step 1002, thereby suppressing the deviation. The division method proceeds to the groove width adjustment step 1004.

[0074] (Groove width adjustment step)

[0075] Figure 10 is a side view showing the groove width adjustment step of the division method shown in Figure 3 by a partial cross-section. Figure 11 is Figure 10 a top view of the main part of the workpiece shown. The groove width adjustment step 1004 is a step of extending the extension sheet 208 after the extension release step 1003 has been carried out to form the division groove 210 into a desired width.

[0076] In the first embodiment, in the groove width adjustment step 1004, the groove width adjustment unit 53 of the control unit 50 of the dividing device 1 controls the drum lifting unit 22 to raise the expansion drum 21 so that the roller member 23 is positioned above the upper surface 18 of the frame mounting plate 11. Then, as Figure 10 shown, after the roller member 23 mounted on the upper end of the expansion drum 21 abuts against the outer periphery of the workpiece 200 and the inner periphery of the frame 209, the expansion piece 208 is pushed upward, and the expansion piece 208 expands in the plane direction. In the groove width adjustment step 1004, as a result of the expansion, a radial tensile force acts on the expansion piece 208.

[0077] In this way, when the tensile force acts radially on the expansion piece 208 adhered to the back surface 207 side of the substrate 202 of the workpiece 200, since the workpiece 200 has been divided at the modified layer 206 along the dividing line 203 as a dividing starting point in the dividing step 1002 and is singulated into individual device chips 201 to form the dividing groove 210 along the dividing line 203, only the expansion piece 208 expands, and the width of the dividing groove 210 is larger than that after the expansion release step 1003. In the groove width adjustment step 1004, since only the expansion piece 208 expands, as Figure 11 shown, the deviation of the width of the dividing groove 210 is suppressed compared to the deviation after the dividing step 1002.

[0078] In addition, in the first embodiment, in the groove width adjustment step 1004, the groove width adjustment unit 53 of the control unit 50 of the dividing device 1 controls the drum lifting unit 22 to make the rising speed of the expansion drum 21 slower than that in the dividing step 1002. Therefore, in the dividing step 1002, when the dividing device 1 expands the expansion piece 208 at the first speed 301 (indicated by arrows in Figure 6 and Figure 7 ), in the groove width adjustment step 1004, the dividing device 1 expands the expansion piece 208 at the second speed 302 lower than the first speed 301 (indicated by arrows in Figure 10 and Figure 11 ).

[0079] Thus, in the first embodiment, in the groove width adjustment step 1004, the dividing device 1 expands the extended sheet 208 at a second speed 302 lower than the first speed 301. Therefore, compared with the deviation after the dividing step 1002, the deviation of the width of the dividing groove 210 can be suppressed. Further, in the first embodiment, in the groove width adjustment step 1004, the dividing device 1 expands the extended sheet 208 at a second speed 302 lower than the first speed 301. However, in the present invention, the dividing device 1 may expand the extended sheet 208 at the same speed as the first speed 301, or may expand the extended sheet 208 at a speed higher than the first speed 301.

[0080] Further, in the first embodiment, in the dividing step 1002 and the groove width adjustment step 1004, with the frame 209 fixed by the dividing device 1, the extended sheet 208 between the outer periphery of the workpiece 200 and the inner periphery of the frame 209 is pushed to expand the extended sheet. Further, in the first embodiment, in the dividing step 1002 and the groove width adjustment step 1004, the extended roller 21 is raised to expand the extended sheet 208. However, the present invention is not limited thereto. The frame fixing unit 10 that holds and fixes the frame 209 may be lowered. In short, as long as the extended roller 21 is relatively raised with respect to the frame fixing unit 10 and the frame fixing unit 10 is relatively lowered with respect to the extended roller 21. The dividing method proceeds to the fixing step 1005.

[0081] (Fixing step)

[0082] Figure 12 is shown in a partial cross-section Figure 3 a side view of the fixing step of the dividing method shown. The fixing step 1005 is a step of fixing the dividing groove 210 to a desired width adjusted by the groove width adjustment step 1004 after the groove width adjustment step 1004 is performed.

[0083] In the first embodiment, in the fixing step 1005, the dividing control unit 51 of the control unit 50 of the dividing device 1 controls the lifting unit 42 for the workbench to raise the chuck workbench 40 until the holding surface 41 and the upper surface 18 of the frame mounting plate 11 are in the same plane. In the fixing step 1005, the dividing control unit 51 of the control unit 50 of the dividing device 1 operates the suction source 43 to suck and hold the back surface 207 side of the plurality of device chips 201 divided from the workpiece 200 and having the width of the dividing groove 210 adjusted, with the extended sheet 208 interposed therebetween on the holding surface 41.

[0084] In the first embodiment, in the fixing step 1005, the dividing control unit 51 of the control unit 50 of the dividing device 1 controls the lifting unit 22 for the drum to lower the expanding drum 21. Then, the expanded expanding sheet 208 tends to contract, but the back surface 207 side of the device chip 201 is attracted and held on the holding surface 41 with the expanding sheet 208 interposed therebetween, so the contraction of the expanding sheet 208 on the holding surface 41 is restricted. Therefore, the width of the dividing groove 210 is maintained at the width adjusted in the groove width adjustment step 1004, as Figure 12 shown, a slack 211 is generated in the expanding sheet 208 on the outer periphery of the workpiece 200 and the inner periphery of the frame 209, causing slack.

[0085] In the first embodiment, in the fixing step 1005, the dividing control unit 51 of the control unit 50 of the dividing device 1 controls the lifting unit 34 to lower the unit main body 31 of the heating unit 30 so that the heat source unit 32 approaches the slack 211 of the expanding sheet 208, and the heat source unit 32 is opposed to the slack 211 in the vertical direction. In the first embodiment, in the fixing step 1005, the dividing control unit 51 of the control unit 50 of the dividing device 1 operates the heat source unit 32, and as Figure 12 shown, controls the rotating unit 33 to rotate the unit main body 31 about the axis, and heats the slack 211 of the expanding sheet 208 over the entire circumference using the heat source unit 32.

[0086] In the first embodiment, in the fixing step 1005, the dividing device 1 contracts the slack 211. In the fixing step 1005, when the dividing control unit 51 of the control unit 50 of the dividing device 1 heats the slack 211 with the heat source unit 32 for a predetermined specified time, the heat source unit 32 is stopped, the unit main body 31 of the heating unit 30 is raised, and the suction source 43 is stopped. The lifting cylinder 15 and the lifting unit 42 for the worktable are controlled to lower the frame mounting plate 11 and the chuck worktable 40. In the first embodiment, in the fixing step 1005, the dividing device 1 removes the frame 209 supporting the workpiece 200 in the opening 212 from the upper surface 18 of the frame mounting plate 11 through a transfer unit (not shown), ending the dividing method. Further, in the fixing step 1005, even when the suction source 43 is stopped, since the slack 211 of the expanding sheet 208 contracts, the width of the dividing groove 210 is fixed to the desired width adjusted in the groove width adjustment step 1004.

[0087] Thus, in the first embodiment, in the fixing step 1005, the workpiece 200 whose width of the dividing groove 210 is formed to a desired width in the groove width adjusting step 1004 is attracted and held by the chuck table 40 with the expansion sheet 208 interposed therebetween, and the expansion sheet 208 between the outer periphery of the workpiece 200 and the inner periphery of the frame 209 is heated to contract the expansion sheet 208, removing the slack 211 generated due to the expansion.

[0088] In addition, the device chips 201 divided one by one are peeled off and removed from the expansion sheet 208 by a pick-up device (not shown).

[0089] As described above, in the dividing method of the first embodiment, after the workpiece 200 is divided in the dividing step 1002, the expansion of the expansion sheet 208 is released in the expansion releasing step 1003. In the dividing method, by releasing the expansion of the expansion sheet 208 at once in the expansion releasing step 1003, the expanded expansion sheet 208 contracts and the width of the dividing groove 210 is reduced. In the dividing method, after the expansion releasing step 1003 is implemented, the groove width adjusting step 1004 is implemented to expand the expansion sheet 208 again. In the groove width adjusting step 1004, only the expansion sheet 208 is expanded, so that the dividing groove 210 with a desired width can be formed, suppressing the deviation of the width of the dividing groove 210. As a result, the dividing method has the effect of being able to form the dividing groove 210 with a desired width. Therefore, the dividing method can suppress the contact between the divided device chips 201 and thus can suppress the damage of the divided device chips 201.

[0090] In addition, in order to divide the workpiece 200 starting from the modified layer 206, it is necessary to expand the expansion sheet 208 at high speed. However, since the rotation of the roller member 23 cannot catch up with the expansion of the expansion sheet 208, when the expansion sheet 208 is expanded at high speed, only the outer peripheral portion of the workpiece 200 is expanded, and the central side of the workpiece 200 cannot be sufficiently extended, and the interval between the device chips 201 in the central portion of the workpiece 200 becomes narrower than that in the outer peripheral portion.

[0091] However, in the dividing method, in the groove width adjusting step 1004, the expansion sheet 208 is expanded at a second speed 302 lower than the first speed 301 in the dividing step 1002. Therefore, in the groove width adjusting step 1004, the expansion sheet 208 can be uniformly expanded, thus suppressing the deviation of the width of the dividing groove 210.

[0092] The control unit 50 of the dividing device 1 according to the first embodiment has: a dividing control unit 51 that expands the extension sheet 208 to form a dividing groove 210; and an extension release unit 52 that releases the extension of the extension sheet 208 after the workpiece 200 is divided. The dividing device 1 releases the extension of the extension sheet 208 once by the extension release unit 52, and the extended extension sheet 208 contracts to narrow the width of the dividing groove 210. In addition, the control unit 50 of the dividing device 1 according to the first embodiment has a groove width adjustment unit 53 that expands the extension sheet 208 after releasing the extension of the extension sheet 208. Therefore, after the release of the extension, only the extension sheet 208 is expanded again, so that a dividing groove 210 with a desired width can be formed, thereby suppressing the deviation of the width of the dividing groove 210. As a result, the dividing device 1 has the effect of being able to form a dividing groove 210 with a desired width.

[0093] 〔Second Embodiment〕

[0094] The dividing device and dividing method according to the second embodiment of the present invention will be described with reference to the drawings. Figure 13 It is a perspective view showing a structural example of the dividing device according to the second embodiment. Figure 14 It is a top view schematically showing the holding step of the dividing method according to the second embodiment. Figure 15 It is a top view schematically showing the dividing step of the dividing method according to the second embodiment. Figure 16 It is a top view of the main part of the workpiece in the dividing step of the dividing method according to the second embodiment. Figure 17 It is a top view of the main part of the workpiece in the extension release step of the dividing method according to the second embodiment. Figure 18 It is a top view of the main part of the workpiece in the groove width adjustment step of the dividing method according to the second embodiment. Figure 19 It is a top view schematically showing the fixing step of the dividing method according to the second embodiment. In addition, in Figure 13 , Figure 14 , Figure 15 , Figure 16 , [[ID=•29]] Figure 17 , Figure 18 and Figure 19 parts that are the same as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

[0095] As Figure 13As shown, the splitting device 1-2 of the second embodiment includes a fixed base 150, a chuck table 40 disposed at the center of the fixed base 150, a first holding unit 131-1 as the first holding unit, a second holding unit 131-2 as the second holding unit, a third holding unit 131-3 as the third holding unit, a fourth holding unit 131-4 as the fourth holding unit, a first moving unit 133-1 as the moving unit, a second moving unit 133-2 as the moving unit, a third moving unit 133-3 as the moving unit, and a fourth moving unit 133-4 as the moving unit.

[0096] The chuck table 40 places the extended sheet 208 on the holding surface 41. The first holding unit 131-1 and the second holding unit 131-2 are arranged opposite to each other across the chuck table 40 on which the extended sheet 208 is placed in a first direction 111 parallel to the horizontal direction. That is, the first holding unit 131-1 and the second holding unit 131-2 are arranged opposite to each other along the first direction 111, positioning the chuck table 40 between them.

[0097] The third holding unit 131-3 and the fourth holding unit 131-4 are arranged opposite to each other across the chuck table 40 on which the extended sheet 208 is placed in a second direction 112 parallel to the horizontal direction and perpendicular to the first direction 111. That is, the third holding unit 131-3 and the fourth holding unit 131-4 are arranged opposite to each other along the second direction 112, positioning the chuck table 40 between them.

[0098] The first holding unit 131-1, the second holding unit 131-2, the third holding unit 131-3, and the fourth holding unit 131-4 hold the extended sheet 208 at positions on the outer peripheral side of the workpiece 200 respectively. Since the structures of the first holding unit 131-1, the second holding unit 131-2, the third holding unit 131-3, and the fourth holding unit 131-4 are substantially the same, the same reference numerals are used to denote the same parts for description.

[0099] The first holding unit 131-1, the second holding unit 131-2, the third holding unit 131-3, and the fourth holding unit 131-4 include: a pair of clamping members 154 that are vertically movably provided on a columnar moving base 153, and the moving base 153 is provided on a fixed base 150; and a moving mechanism 155 that moves in a direction in which the pair of clamping members 154 approach each other and a direction in which they move away from each other. The pair of clamping members 154 are arranged at intervals in the vertical direction, approach each other through the moving mechanism 155, and clamp and hold the extension piece 208 therebetween. The moving mechanism 155 is provided on the moving base 153. In addition, the moving base 153 provided with the pair of clamping members 154 and the moving mechanism 155 of each of the holding units 131-1, 131-2, 131-3, and 131-4 is movably provided on the fixed base 150 in the first direction 111 or the second direction 112.

[0100] The first moving unit 133-1 and the second moving unit 133-2 can move the first holding unit 131-1 and the second holding unit 131-2 in the first direction 111 in a direction in which they separate from each other. In the second embodiment, the first moving unit 133-1 moves the moving base 153 provided with the first holding unit 131-1 relative to the fixed base 150 in the first direction 111. In the first embodiment, the second moving unit 133-2 moves the moving base 153 provided with the second holding unit 131-2 relative to the fixed base 150 in the first direction 111.

[0101] The third moving unit 133-3 and the fourth moving unit 133-4 can move the third holding unit 131-3 and the fourth holding unit 131-4 in the second direction 112 in a direction in which they separate from each other. In the second embodiment, the third moving unit 133-3 moves the moving base 153 provided with the third holding unit 131-3 relative to the fixed base 150 in the second direction 112. In the second embodiment, the fourth moving unit 133-4 moves the moving base 153 provided with the fourth holding unit 131-4 relative to the fixed base 150 in the second direction 112.

[0102] The first moving unit 133-1, the second moving unit 133-2, the third moving unit 133-3, and the fourth moving unit 133-4 are extension units that extend the extension piece 208 held by the first holding unit 131-1, the second holding unit 131-2, the third holding unit 131-3, and the fourth holding unit 131-4. The structures of the first moving unit 133-1, the second moving unit 133-2, the third moving unit 133-3, and the fourth moving unit 133-4 are substantially the same, so the same reference numerals are used to denote the same parts for description.

[0103] The first moving unit 133-1, the second moving unit 133-2, the third moving unit 133-3, and the fourth moving unit 133-4 include: a motor 137-2 that can move the holding units 131-1, 131-2, 131-3, and 131-4 in the first direction 111 or the second direction 112; and a ball screw 138-2 that rotates around an axis by the motor 137-2 to move the moving base 153 in the first direction 111 or the second direction 112.

[0104] In addition, the dividing device 1-2 includes: a frame pasting unit (not shown) that holds the frame 209 and pastes the frame 209 onto the extension piece 208 held by the chuck table 40; and a cutter that cuts off the remaining portion of the extension piece 208 pasted to the frame 209. The remaining portion is the portion on the outer peripheral side of the frame 209 of the extension piece 208.

[0105] Similar to the first embodiment, the dividing method of the second embodiment includes a holding step 1001, a dividing step 1002, an extension release step 1003, a groove width adjustment step 1004, and a fixing step 1005.

[0106] The holding step 1001 of the dividing method of the second embodiment is a step of: pasting the workpiece 200 on the extension piece 208 and holding a position on the extension piece 208 that is on the outer peripheral side of the workpiece 200 relative to the workpiece 200. In the holding step 1001 of the dividing method of the second embodiment, the workpiece 200 is pasted on a long strip-shaped extension piece 208 wound around a roller (not shown), and as Figure 14 shown, the long strip-shaped extension piece 208 is cut into a rectangle before and after pasting the workpiece 200. In addition, in the second embodiment, the back surface 207 side of the workpiece 200 is pasted at the center of the extension piece 208 cut into a rectangle. Figure 14 The device 204 and the modified layer 206 are omitted. In addition, in the holding step 1001 of the dividing method of the first embodiment, in the present invention, when a front protective tape (not shown) is pasted on the workpiece 200, it is desirable to peel off the front protective tape after pasting the workpiece 200 on the extension piece 208 to reduce the risk of damage to the workpiece 200.

[0107] In addition, in the holding step 1001 of the splitting method of the first embodiment, the splitting control unit 51 of the control unit 50 of the splitting device 1-2 controls each of the holding units 131-1, 131-2, 131-3, and 131-4 to hold and fix the position of the extended sheet 208 that is cut into a rectangle and has the workpiece 200 pasted in the center on the outer peripheral side of the workpiece 200 between a pair of clamping members 154 of each of the holding units 131-1, 131-2, 131-3, and 131-4.

[0108] In the splitting step 1002 of the splitting method of the second embodiment, the splitting control unit 51 of the control unit 50 of the splitting device 1-2 controls each of the moving units 133-1, 133-2, 133-3, and 133-4 to move the first holding unit 131-1 and the second holding unit 131-2 in a direction away from each other at the first speed 301, and to move the third holding unit 131-3 and the fourth holding unit 131-4 in a direction away from each other at the first speed 301, as Figure 15 shown, to expand the extended sheet 208 along the first direction 111 and the second direction 112 simultaneously. Similar to the first embodiment, the workpiece 200 is split into individual devices 204 starting from the modified layer 206 along the splitting predetermined line 203, as Figure 16 shown, and is singulated into individual device chips 201 to form splitting grooves 210 along the splitting predetermined line 203.

[0109] In addition, since the modified layer 206 is not formed uniformly, in the splitting step 1002, there is a deviation in the timing of fracture when the extended sheet 208 expands. That is, in the splitting step 1002, there is almost no case where all the modified layers 206 break simultaneously. Therefore, similar to the first embodiment, as Figure 16 shown, there is a deviation in the width of the splitting groove 210 after the splitting step 1002.

[0110] In addition, in the second embodiment, in the splitting step 1002, the splitting device 1-2 moves each of the holding units 131-1, 131-2, 131-3, and 131-4 at the first speed 301 (for example, 200 mm / sec) to expand the extended sheet 208 by, for example, 10 mm. In the first embodiment, it expands along the first direction 111 and the second direction 112 simultaneously, but the present invention is not limited thereto. For example, it may be split by expanding the extended sheet 208 along the first direction 111 first and then expanding and splitting it along the second direction 112. In the present invention, in the splitting step 1002, the expansion amount and the first speed 301 may also be different in the first direction 111 and the second direction 112.

[0111] In the extension release step 1003 of the splitting method according to the second embodiment, the extension release unit 52 of the control unit 50 of the splitting device 1-2 controls each of the moving units 133-1, 133-2, 133-3, 133-4 to move the first holding unit 131-1 and the second holding unit 131-2 closer to each other to the position in the holding step 1001, and to move the third holding unit 131-3 and the fourth holding unit 131-4 closer to each other to the position in the holding step 1001, thereby releasing the extension in the plane direction of the extension sheet 208. Thus, as Figure 17 shown, similar to the first embodiment, compared with after the splitting step 1002, the width of the splitting groove 210 is reduced, thereby suppressing the deviation.

[0112] In the groove width adjustment step 1004 of the splitting method according to the second embodiment, the groove width adjustment unit 53 of the control unit 50 of the splitting device 1-2 controls each of the moving units 133-1, 133-2, 133-3, 133-4 to move the first holding unit 131-1 and the second holding unit 131-2 in a direction away from each other at a second speed 302 lower than the first speed 301, and to move the third holding unit 131-3 and the fourth holding unit 131-4 in a direction away from each other at a second speed 302 lower than the first speed 301, as Figure 15 shown, the extension sheet 208 is extended simultaneously along the first direction 111 and the second direction 112.

[0113] The workpiece 200 has been split at the modification layer 206 along the splitting predetermined line 203 as the splitting starting point in the splitting step 1002, and is singulated according to each device chip 201, and a splitting groove 210 along the splitting predetermined line 203 is formed. Therefore, only the extension sheet 208 is extended, and compared with after the extension release step 1003, the width of the splitting groove 210 is enlarged. In the groove width adjustment step 1004, since only the extension sheet 208 is extended, as Figure 18 shown, compared with the deviation after the splitting step 1002, the deviation of the width of the splitting groove 210 is suppressed.

[0114] In the fixing step 1005 of the splitting method according to the second embodiment, in a state where the extension sheet 208 is sandwiched between a pair of clamping members 154 of each of the holding units 131-1, 131-2, 131-3, 131-4 and the splitting groove 210 is formed to have a desired width, as Figure 19As shown, the dividing control section 51 of the control unit 50 of the dividing device 1-2 controls the frame pasting unit to paste the frame 209 around the workpiece 200 of the extended sheet 208. In the fixing step 1005 of the dividing method of the second embodiment, the dividing control section 51 of the control unit 50 of the dividing device 1-2 controls the cutter to cut off the remaining part of the extended sheet 208 pasted to the frame 209, and fixes the workpiece 200 to the frame 209 through the extended sheet 208 while the width of the dividing groove 210 of the workpiece 200 is maintained at a desired width.

[0115] Thus, in the second embodiment, in the fixing step 1005, the frame 209 is pasted on the extended sheet 208 in a state where the extended sheet 208 is extended by the groove width adjustment step 1004 in such a manner that the workpiece 200 is disposed within the opening 212 of the frame 209 having the opening 212, and the dividing groove 210 is fixed at a desired width.

[0116] After dividing the workpiece 200, the dividing method and the dividing device 1-2 of the second embodiment release the extension of the extended sheet 208, temporarily reduce the width of the dividing groove 210, and only extend the extended sheet 208 again, thereby enabling the formation of a dividing groove 210 with a desired width, and suppressing the deviation of the width of the dividing groove 210. As a result, similar to the first embodiment, the dividing method and the dividing device 1-2 achieve the effect of being able to form a dividing groove 210 with a desired width.

[0117] In addition, the present invention is not limited to the above embodiments. That is, various modifications can be made and implemented without departing from the gist of the present invention. In the first and second embodiments, the modified layer 206 is used as the dividing starting point, but in the present invention, the dividing starting point is not limited to the modified layer 206. In the present invention, the dividing starting point may also be a cutting groove or a laser processing groove recessed from the back surface 207 of the substrate 202 of the workpiece 200.

Claims

1. A method for dividing a workpiece having a dividing starting point formed along a predetermined dividing line and directly attached to an expansion sheet, characterized in that: The segmentation method has the following steps: a dividing step of expanding the expansion piece and dividing the workpiece along the dividing starting point to form a dividing groove along the predetermined dividing line; an expansion canceling step of canceling the expansion of the expansion piece after the segmentation step is performed; and a groove width adjustment step, after the expansion release step is performed, expanding the expansion piece to form the dividing groove to a desired width; The workpiece is mounted on a frame having an opening via the expansion piece and is arranged in the opening. In the dividing step, the expansion releasing step, and the groove width adjusting step, the expansion piece is expanded by pressing the expansion piece between the outer periphery of the workpiece and the inner periphery of the frame while the frame is fixed by the same frame fixing unit.

2. The segmentation method according to claim 1, wherein: In the splitting step, the expansion piece is expanded at a first speed. In the groove width adjustment step, the expansion piece is expanded at a second speed lower than the first speed.

3. The segmentation method according to claim 1 or 2, wherein: The dividing method further comprises the following fixing step: after the groove width adjustment step is performed, fixing the dividing groove according to the desired width.

4. The segmentation method according to claim 3, wherein: In the fixing step, with the frame fixed by the frame fixing unit, the workpiece, whose dividing groove is formed to the desired width by the groove width adjustment step, is sucked and held by the suction and holding component through the expansion piece, and the expansion piece between the outer periphery of the workpiece and the inner periphery of the frame is heated to shrink the expansion piece, thereby removing the slack caused by the expansion.

5. A segmentation device, which implements the segmentation method according to any one of claims 1 to 4, wherein: The segmentation device has: a frame fixing unit that fixes the frame; an expansion unit that expands the expansion piece; and A controller that controls the expansion unit. The controller contains: a splitting control unit that expands the expansion piece and splits the workpiece along the splitting starting point to form a splitting groove along the planned splitting line; an expansion releasing portion for releasing the expansion of the expansion piece after the workpiece is divided; as well as The groove width adjusting portion expands the expansion piece after releasing the expansion of the expansion piece to form the dividing groove to a desired width.

6. A dividing device that implements a dividing method, which is a dividing method for a workpiece that has a dividing start point formed along a dividing predetermined line and is pasted on an extension sheet. The dividing method has the following steps: a dividing step of expanding the extension sheet and dividing the workpiece along the dividing start point to form a dividing groove along the dividing predetermined line; an expansion release step of releasing the expansion of the extension sheet after the dividing step is implemented; and a groove width adjustment step of expanding the extension sheet after the expansion release step is implemented to form the dividing groove into a desired width, where the dividing device includes: a first holding unit and a second holding unit, which are disposed opposite to each other in a first direction parallel to the horizontal direction, and the first holding unit and the second holding unit hold the extension sheet by clamping the portion of the extension sheet on the outer peripheral side of the workpiece; a third holding unit and a fourth holding unit, which are disposed opposite to each other in a second direction parallel to the horizontal direction and perpendicular to the first direction, and the third holding unit and the fourth holding unit hold the extension sheet by clamping the portion of the extension sheet on the outer peripheral side of the workpiece; an expansion unit that expands the extension sheet; and a controller that controls the expansion unit, the expansion unit includes: a first moving unit and a second moving unit, which can move the first holding unit and the second holding unit in the first direction in a direction away from each other; and a third moving unit and a fourth moving unit, which can move the third holding unit and the fourth holding unit in the second direction in a direction away from each other; the controller includes: a dividing control unit that, in the dividing step, controls the first moving unit, the second moving unit, the third moving unit, and the fourth moving unit to move the first holding unit and the second holding unit in a direction away from each other, and move the third holding unit and the fourth holding unit in a direction away from each other, so as to expand the extension sheet and divide the workpiece along the dividing start point to form a dividing groove along the dividing predetermined line; an expansion release unit that, in the expansion release step, after the workpiece is divided, controls the first moving unit, the second moving unit, the third moving unit, and the fourth moving unit to move the first holding unit and the second holding unit closer to each other, and move the third holding unit and the fourth holding unit closer to each other, so as to release the expansion of the extension sheet; and A groove width adjustment unit, which, in the groove width adjustment step, after releasing the expansion of the expansion piece, controls the first moving unit, the second moving unit, the third moving unit, and the fourth moving unit to move the first holding unit and the second holding unit in a direction away from each other, and moves the third holding unit and the fourth holding unit in a direction away from each other, and expands the expansion piece to form the split groove into a desired width.

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