Method for dividing a substrate

Abstract

To expand favorably a plurality of chip spacing formed on a substrate.SOLUTION: After a modification layer formation step and before a chip spacing expansion step in an adhesion step, an expanded tape 2 is brought into close contact with a substrate 1. Thus, when the expanded tape 2 is expanded in the chip spacing expansion step, the substrate 1 is favorably divided starting from a modified layer 105 to favorably form multiple chips 107. A spacing 109 between the multiple chips 107 can be favorably expanded.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a method for dividing a substrate.

Background Art

[0002] Conventionally, as shown in Patent Document 1, as a method for dividing a substrate in which a modified layer serving as a division starting point is formed inside and the substrate is adhered to an expandable tape, by expanding the expandable tape, the substrate is divided starting from the modified layer, or when the substrate has already been divided into chips starting from the modified layer, there is a method of widening the interval between the chips.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above-described division method, if the adhesion between the expandable tape and the substrate is weak, when the expandable tape is expanded, the substrate may not be expanded together, and there may be a region on the substrate that is not divided into chips.

[0005] Also, after an expandable tape is adhered to the back surface side of the substrate, a laser beam is irradiated through the expandable tape from the back surface side to form a modified layer serving as a division starting point on the substrate, and then the expandable tape is expanded to divide the substrate into chips along the division starting point, or when the substrate has already been divided into chips, a process of widening the interval between the chips may be performed.

[0006] However, in this process, it takes time from when the expandable tape is adhered to the substrate until the expandable tape is expanded. For this reason, the adhesion between the expandable tape and the substrate decreases, and it may be difficult to widen the chip interval well when the expandable tape is expanded.

[0007] Therefore, an object of the present invention is to form a plurality of chips by satisfactorily dividing a substrate by expanding an expandable tape, and to satisfactorily widen the intervals between the plurality of chips.

Means for Solving the Problems

[0008] A method for dividing a substrate according to the present invention is a method for dividing a substrate along a planned division line, including an expandable tape attaching step of attaching an expandable tape to the back surface of the substrate, and after the expandable tape attaching step is performed, irradiating a laser beam having a wavelength that is transmissive to the substrate along the planned division line with the condensing point positioned inside the substrate to form a modified layer serving as a starting point for division inside the substrate, a modified layer forming step; and a chip interval expanding step of expanding the expandable tape after the modified layer forming step is performed to widen the intervals formed between a plurality of chips starting from the modified layer. The method further includes an adhering step of adhering the expandable tape to the substrate after the modified layer forming step and before the chip interval expanding step is performed. In the adhering step, a roller may be rolled on either the substrate or the expandable tape while either one of them is supported by a support table. An adhesive layer is laminated on the expandable tape, and in the chip interval expanding step, the adhesive layer may be divided along the modified layer.

Advantages of the Invention

[0009] In the method for dividing a substrate according to the present invention, in the adhering step after the modified layer forming step and before the chip interval expanding step, the expandable tape is adhered to the substrate. Therefore, in the chip interval expanding step, when the expandable tape is expanded, the substrate is pulled together with the expandable tape, and it is possible to satisfactorily divide the substrate starting from the modified layer to form a plurality of chips satisfactorily, and to satisfactorily widen the intervals between the plurality of chips.

Brief Description of the Drawings

[0010]

Figure 1

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Figure 9

Mode for Carrying Out the Invention

[0011] [First Embodiment] The disk-shaped substrate 1 shown in FIG. 1 is, for example, a disk-shaped semiconductor wafer, and its material is silicon, sapphire, gallium arsenide, SiC, or the like. On the surface 10 of the substrate 1, a grid-like planned division line 100 is formed, and a device 101 is formed in the region partitioned by the planned division line 100. Further, a protective sheet 5 for protecting the device 101 may be attached to the surface 10 of the substrate 1.

[0012] In the present embodiment, the substrate 1 is handled in the state of a work set 19 including an annular frame 3 and an expand tape 2 as shown in FIG. 1. Hereinafter, the method for dividing the substrate according to the present embodiment will be described. This method includes forming a work set 19 and dividing the substrate 1 in the formed work set 19 along the planned division line 100.

[0013] (Expansion Tape Attachment Step) In this step, first, the substrate 1 is positioned inside the circular opening 30 of the annular frame 3. Then, the expansion tape 2 is attached to the back surface 11 of the substrate 1 and the annular frame 3 from the back surface 11 side of the substrate 1. Thereby, the work set 19 is formed.

[0014] Note that one side surface of the expansion tape 2 is an adhesive surface 20 having adhesiveness. Further, a paste layer 4 is laminated on the central portion of the adhesive surface 20 of the expansion tape 2. The paste layer 4 is, for example, DAF (Die Attach Film).

[0015] The attachment of the expansion tape 2 to the back surface 11 of the substrate 1 and the annular frame 3 is performed by the expansion tape attachment device 12 shown in FIG. 2. The expansion tape attachment device 12 includes a first support table 61 and a roller 120. The first support table 61 has a support surface 610 for supporting the protective sheet 5 attached to the surface 10 of the substrate 1 and the annular frame 3. The roller 120 is a cylindrical member extending in the depth direction of the paper surface (Y-axis direction). A rolling mechanism (not shown) is connected to the roller 120, and the roller 120 rolls in the X-axis direction by this rolling mechanism. Note that the protective sheet 5 may not be attached to the substrate 1 and may be placed on the support surface 610.

[0016] When attaching the expansion tape 2 to the back surface 11 of the substrate 1 and the annular frame 3 by the expansion tape attachment device 12, first, the annular frame 3 is placed on the support surface 610 of the first support table 61. Also, the substrate 1 is placed on the inside of the opening 30 of the annular frame 3 on the support surface 610 with its surface 10 facing downward. Thereby, the back surface 11 of the substrate 1 is exposed by the first support table 61.

[0017] Then, the expandable tape 2 is placed on the back surface 11 of the annular frame 3 and the substrate 1 such that the adhesive surface 20 faces downward and the adhesive layer 4 overlaps the back surface 11 of the substrate 1. As a result, the adhesive layer 4 of the expandable tape 2 comes into contact with the back surface 11 of the substrate 1, and the adhesive layer 4 is adhered to the back surface 11 of the substrate 1. Further, the adhesive surface 20 outside the adhesive layer 4 in the expandable tape 2 comes into contact with the upper surface of the annular frame 3, and the expandable tape 2 is adhered to the annular frame 3.

[0018] Next, a roller 120 is positioned at the end on the +X direction side of the contact surface 21, which is the surface opposite to the adhesive surface 20 in the expandable tape 2, and the roller 120 is rolled in the -X direction. As a result, the adhesive layer 4 of the expandable tape 2 is pressed against the back surface 11 of the substrate 1, and the adhesion between the adhesive layer 4 and the back surface 11 of the substrate 1 is improved. Also, the adhesive surface 20 of the expandable tape 2 is pressed against the annular frame 3, and the adhesion between the adhesive surface 20 and the annular frame 3 is improved. In this way, a workpiece set 19 in which the substrate 1, the expandable tape 2, and the annular frame 3 are integrated as shown in FIG. 1 is formed.

[0019] Note that, with the roller 120 positioned at the end on the -X direction side of the contact surface 21, the first support table 61 is horizontally moved in the -X direction, and the roller 120 is moved relative to the first support table 61 in the +X direction, thereby pressing the expandable tape 2 against the back surface 11 of the substrate 1 and the annular frame 3.

[0020] (Modified layer formation step) In this step, after the expandable tape sticking step is performed, laser processing is performed on the planned division line 100 of the substrate 1 by the laser processing apparatus 13 shown in FIG. 3. That is, in this step, a laser beam having a wavelength that is transmissive to the substrate 1 is irradiated along the planned division line 100 with the focus point positioned inside the substrate 1, and a modified layer serving as a division starting point is formed inside the substrate 1.

[0021] As shown in FIG. 3, the laser processing apparatus 13 includes a second support table 62. The second support table 62 has a support surface 620 for supporting the workpiece set 19.

[0022] On the side of the second support table 62, four frame fixing units 628 are arranged so as to surround the second support table 62. In FIG. 3, two of these frame fixing units 628 are shown. The frame fixing unit 628 is a clamp that clamps and fixes the annular frame 3 from the outer peripheral side.

[0023] Also, the second support table 62 is connected to a horizontal movement mechanism (not shown). The second support table 62 and the frame fixing unit 628 are integrally moved horizontally by this horizontal movement mechanism. Furthermore, the second support table 62 is connected to a rotation mechanism (not shown). The second support table 62 and the frame fixing unit 628 are integrally rotated by this rotation mechanism.

[0024] The laser processing apparatus 13 also includes an irradiation head 7 that irradiates the substrate 1 of the workpiece set 19 supported on the support surface 620 with a laser beam 70 having a wavelength that is transmissive to the substrate 1.

[0025] When performing laser processing on the division planned line 100 of the substrate 1, first, the workpiece set 19 is removed from the expand tape attaching device 12 (see FIG. 2). As shown in FIG. 3, the substrate 1 of the workpiece set 19 is placed on the support surface 620 of the second support table 62 in the laser processing apparatus 13 with the protective sheet 5 attached to its surface 10 facing downward. Thereby, the second support table 62 supports the substrate 1 via the protective sheet 5. At this time, an attraction source (not shown) connected to the second support table 62 may be operated to transmit an attraction force to the support surface 620 of the second support table 6, thereby attracting and holding the substrate 1 by the support surface 620.

[0026] Further, the frame fixing unit 628 clamps the annular frame 3 of the work set 19 from the outer peripheral side to fix the annular frame 3.

[0027] Next, with the substrate 1 being supported by the second support table 62, the irradiation head 7 of the laser processing apparatus 13 is positioned above the substrate 1. At this time, the direction of the irradiation head 7 is set downward so that the laser beam 70 irradiated from the irradiation head 7 is directed in the -Z direction. Also, the focusing adjustment of the irradiation head 7 is performed so that the focal point 700 of the laser beam 70 is positioned inside the substrate 1. Furthermore, the position of the second support table 62 is adjusted by the horizontal movement mechanism and the rotation mechanism so that the irradiation position of the laser beam 70 is positioned at the -X direction side end of one division planned line 100 on the substrate 1.

[0028] Then, while irradiating the laser beam 70 from the irradiation head 7, the second support table 62 is moved in the -X direction by the horizontal movement mechanism. As a result, the irradiation head 7 relatively moves in the +X direction with respect to the substrate 1 supported by the second support table 62, and the laser beam 70 from the irradiation head 7 is irradiated along the division planned line 100.

[0029] Thereby, as shown in FIG. 4, a modified layer 105 is formed inside the substrate 1. This modified layer 105 serves as a division starting point of the substrate 1 when the substrate 1 is divided in a chip interval expansion step described later.

[0030] Thereafter, by moving the second support table 62 in the Y-axis direction by the horizontal movement mechanism, the irradiation position of the laser beam 70 is positioned on another division planned line 100 parallel to the division planned line 100 where the laser beam 70 has already been irradiated, and laser processing is similarly performed on that division planned line 100. Further, by rotating the second support table 62 by 90 degrees by the rotation mechanism, the irradiation position of the laser beam 70 is positioned on one division planned line 100 that intersects the division planned line 100 where the laser beam 70 has already been irradiated, and similar laser processing is performed on this division planned line 100. In this way, finally, the laser beam 70 is irradiated along all the planned division lines 100 shown in FIG. 1, and the modified layer 105 is formed inside the substrate 1 along each planned division line 100.

[0031] (Adhesion step) In this step, after the execution of the modified layer formation step and before the execution of the chip interval expansion step described later, the expand tape 2 is adhered to the substrate 1 of the work set 19.

[0032] When adhering the expand tape 2 to the substrate 1, with either the substrate 1 or the expand tape 2 of the work set 19 supported by the second support table 62 of the laser processing apparatus 13, a roller is rolled on the other. In the present embodiment, as shown in FIG. 4, with the substrate 1 supported by the second support table 62, the roller 130 provided in the laser processing apparatus 13 is rolled on the expand tape 2. This roller 130 is a cylindrical member extending in the depth direction of the paper surface (Y-axis direction), similar to the roller 120 of the expand tape sticking device 12 shown in FIG. 2, and is configured to roll in the X-axis direction by a rolling mechanism (not shown).

[0033] Specifically, first, with the substrate 1 supported by the second support table 62, as shown in FIG. 4, the roller 130 is brought into contact with a portion on the +X direction side of the contact surface 21 of the expand tape 2.

[0034] Then, by rolling the roller 130 in the -X direction by the rolling mechanism, the roller 130 presses the expand tape 2 against the substrate 1. Thereby, the expand tape 2 adheres to the substrate 1.

[0035] At this time, vibration may occur in the chips divided from the substrate 1 due to the rolling operation of the roller 130, and a part of the substrate 1 may be divided starting from the modified layer 105, and chips 107 as shown in FIG. 6 may be formed.

[0036] In addition, in the adhesion step, instead of rolling the roller 130 in the -X direction, the roller 130 may be fixed to the end portion on the +X direction side of the contact surface 21, and the second support table 62 may be horizontally moved in the +X direction. Also in this case, the roller 130 presses the expand tape 2 against the substrate 1, and the expand tape 2 adheres to the substrate 1.

[0037] (Chip interval expansion step) In this step, after the modification layer formation step and the adhesion step are performed, the expand tape 2 is expanded by the expander 14 shown in FIGS. 5 and 6, and the interval 109 formed between the plurality of chips 107 with the modification layer 105 as the starting point is widened.

[0038] The expander 14 includes a holding table 63. The holding table 63 includes a holding surface 630 for holding the work set 19. Further, the expander 14 includes four frame holding units 64 for fixing the annular frame 3 around the holding table 63, and two of those frame holding units 64 are shown in FIG. 5. The four frame holding units 64 are arranged, for example, at equal intervals on the same circumference. The frame holding unit 64 includes a clamping clamp 648 that clamps and fixes the annular frame 3 from the outer peripheral side, and a shaft portion 644 that supports the clamping clamp 648.

[0039] The expander 14 also includes four cylindrical pushing-up members 9, and two of those pushing-up members 9 are shown in FIG. 5. The four pushing-up members 9 are arranged, for example, at equal intervals on the same circumference inside the circle formed by the four frame holding units 64. The pushing-up member 9 and the holding table 63 are connected to a lifting mechanism (not shown), and are lifted and lowered in the Z-axis direction by this lifting mechanism. A spherical roller member 90 is rotatably attached to the upper end of the pushing-up member 9. The roller member 90 contacts the contact surface 21 of the expand tape 2 when the pushing-up member 9 pushes up the expand tape 2, and relieves friction.

[0040] When expanding the expand tape 2, first, remove the work set 19 from the laser processing device 13 (see FIG. 4), and peel off the protective sheet 5 adhered to the surface 10 from the substrate 1. Then, as shown in FIG. 5, with the surface 10 of the substrate 1 facing upward, place the substrate 1 of the work set 19 on the holding surface 630 of the holding table 63. Further, clamp and fix the annular frame 3 of the work set 19 by the clamping clamps 648 of the four frame holding units 64.

[0041] As a result, as shown in FIG. 5, the roller member 90 of the pushing member 9 contacts the contact surface 21 of the expand tape 2 in the work set 19. And in this state, raise the pushing member 9 and the holding table 63 in the +Z direction. Thereby, as shown in FIG. 6, the roller member 90 pushes up the expand tape 2, and expands the expand tape 2 in the plane direction (X-axis direction and Y-axis direction).

[0042] With such expansion of the expand tape 2 in the plane direction, a radial tensile force is applied to the substrate 1 adhered to the expand tape 2. As a result, starting from the modified layer 105, the substrate 1 is divided to form a plurality of chips 107, and an interval 109 is formed between the plurality of chips 107. Also, the interval 109 between the formed chips 107 is widened to a predetermined size.

[0043] Also, in the chip interval expansion step, when the expand tape 2 is expanded as described above, the adhesive layer 4 laminated on the expand tape 2 is also divided along the modified layer 105. That is, in the chip interval expansion step, due to the expansion of the expand tape 2, the substrate 1 and the adhesive layer 4 are integrally divided along the modified layer 105.

[0044] As described above, in the present embodiment, after the implementation of the modified layer formation step and before the implementation of the chip interval expansion step, in the adhesion step, the expand tape 2 is adhered to the substrate 1. Therefore, for example, even if the adhesion degree between the substrate 1 and the expand tape 2 decreases over time, the adhesion degree between the two can be restored by implementing the adhesion step. Thus, in the chip interval expansion step, when the expand tape 2 is expanded, the substrate 1 is pulled together with the expand tape 2, and the substrate 1 can be preferably divided starting from the modified layer 105 to preferably form a plurality of chips 107, and the interval 109 between the plurality of chips 107 can be preferably widened. Also, in the adhesion step, as the roller 130 rolls while applying pressure to the substrate, due to the minute movement of the chip 107 caused by the pressing of the roller 130, cracks extend starting from the modified layer 105, and in the chip interval expansion step, there is also an effect that the interval 109 between the chips 107 is preferably widened.

[0045] Also, in the present embodiment, in the adhesion step, the roller 130 is rolled with respect to the expand tape 2 while the substrate 1 is supported by the second support table 62. Therefore, the expand tape 2 can be easily adhered to the substrate 1. Note that the adhesion step may be implemented in a state where the substrate 1 is supported by the holding table 63 of the expander 14 instead of the second support table 62 of the laser processing apparatus 13.

[0046] Further, an adhesive layer 4 is laminated on the expand tape 2 adhered to the substrate 1, and this adhesive layer 4 is divided along the modified layer 105 together with the substrate 1 in the chip interval expansion step. Each of the divided adhesive layers 4 serves as an adhesive when laminating the chips 107.

[0047] In the chip interval expansion step, as shown in FIG. 6, after expanding the interval 109 between the chips 107 to a predetermined size, the holding surface 630 of the holding table 63 may be connected to a suction source (not shown), and each chip 107 may be suction-held from the expand tape 2 side by the holding surface 630. Thereby, the interval 109 between the chips 107 can be maintained.

[0048] [Second Embodiment] In this embodiment, in the reformed layer formation step, the point that the laser beam 70 is irradiated onto the substrate 1 through the second support table 62 is different from the first embodiment. Hereinafter, the substrate splitting method according to this embodiment will be described. (Expand Tape Attachment Step) Also in this embodiment, first, as shown in FIG. 2, in the same manner as the expand tape attachment step of the first embodiment, the expand tape 2 is attached to the back surface 11 of the substrate 1 to form the work set 19.

[0049] (Reformed Layer Formation Step) In this step, after the expand tape attachment step is performed, as shown in FIG. 7, laser processing on the planned splitting line 100 of the substrate 1 is performed by the above-described laser processing apparatus 13.

[0050] As described above, the laser processing apparatus 13 includes the second support table 62 and the frame fixing unit 628, and these are horizontally moved or rotationally moved by a horizontal movement mechanism and a rotation mechanism (not shown). However, in this embodiment, the second support table 62 is made of a translucent or transparent material (for example, glass) that transmits the laser beam 70 irradiated from the irradiation head 7.

[0051] In this embodiment, when performing laser processing on the planned division line 100 of the substrate 1 by the laser processing apparatus 13, first, as shown in FIG. 7, with the contact surface 21 of the expandable tape 2 in the work set 19 facing downward, the substrate 1 of the work set 19 is placed on the support surface 620 of the second support table 62 via the expandable tape 2. Thereby, the second support table 62 supports the expandable tape 2 (that is, the second support table 62 supports the substrate 1 via the expandable tape 2). At this time, an aspiration source (not shown) connected to the second support table 62 may be operated to transmit the aspiration force to the support surface 620 of the second support table 62, thereby aspirating and holding the expandable tape 2 by the support surface 620.

[0052] Further, the annular frame 3 of the work set 19 is clamped from the outer peripheral side by the frame fixing unit 628 to fix the annular frame 3.

[0053] Next, with the substrate 1 supported by the second support table 62, the irradiation head 7 is positioned below the second support table 62. Also, as shown in FIG. 7, the orientation of the irradiation head 7 is set upward so that the laser beam 70 irradiated from the irradiation head 7 is directed in the +Z direction. Further, the focusing adjustment of the irradiation head 7 is performed so that the laser beam 70 passes through the second support table 62 and is irradiated toward the substrate 1, and its focus point 700 is positioned inside the substrate 1. Furthermore, the position of the second support table 62 is adjusted by the horizontal movement mechanism and the rotation mechanism so that the irradiation position of the laser beam 70 is positioned at the -X direction side end of one planned division line 100 on the substrate 1.

[0054] While irradiating the laser beam 70 from the irradiation head 7, the second support table 62 and the frame fixing unit 628 are moved in the -X direction by the horizontal movement mechanism (not shown) described above. As a result, the irradiation head 7 relatively moves in the +X direction with respect to the substrate 1 supported by the second support table 62, and the laser beam 70 from the irradiation head 7 is irradiated along the division planned line 100. Thereby, as shown in FIG. 8, a modified layer 105 is formed inside the substrate 1.

[0055] Thereafter, in the same manner as in the first embodiment, while moving the second support table 62 by the horizontal movement mechanism and the rotation mechanism, the laser beam 70 is irradiated to form the modified layer 105 along all the division planned lines 100 inside the substrate 1.

[0056] Note that when performing the modified layer forming step in the second embodiment, the protective sheet 5 may not be attached to the surface 10 of the substrate 1.

[0057] (Adhesion step) In this step, in the same manner as in the first embodiment, the expand tape 2 is adhered to the substrate 1 of the work set 19 after the modified layer forming step and before the chip interval expanding step. When the above-described modified layer forming step is performed in a state where the protective sheet 5 is not attached to the surface 10 of the substrate 1, the protective sheet 5 is attached to the surface 10 of the substrate 1 at the start of the adhesion step.

[0058] When adhering the expand tape 2 to the substrate 1, in this embodiment, as shown in FIG. 8, the roller 130 is rolled on the substrate 1 while the expand tape 2 is supported by the second support table 62.

[0059] Specifically, first, while the expand tape 2 is supported by the second support table 62, the roller 130 is brought into contact with the end portion on the +X direction side of the surface 50 of the protective sheet 5 attached to the substrate 1.

[0060] Then, by rolling the roller 130 in the -X direction by a rolling mechanism (not shown), the expand tape 2 is pressed against the substrate 1, and the expand tape 2 adheres closely to the substrate 1.

[0061] Note that, similar to the adhesion step in the first embodiment, vibration may be transmitted into the substrate 1 by the rolling motion of the roller 130, and a part of the substrate 1 may be divided starting from the modified layer 105, and chips 107 as shown in FIG. 6 may be formed.

[0062] Also, in the adhesion step, instead of rolling the roller 130 in the -X direction, the roller 130 may be fixed to the +X-direction side end of the contact surface 21, and the second support table 62 may be horizontally moved in the +X direction.

[0063] (Chip interval expansion step) In this step, in the same manner as the chip interval expansion step in the first embodiment, the expand tape 2 is expanded by the expander 14 shown in FIGS. 5 and 6, and the interval 109 formed between the plurality of chips 107 starting from the modified layer 105 is widened. That is, by expanding the expand tape 2, the substrate 1 is divided starting from the modified layer 105 to form a plurality of chips 107, and the interval 109 between the formed chips 107 is widened to a predetermined size. Also, similar to the chip interval expansion step in the first embodiment, when the expand tape 2 is expanded, the adhesive layer 4 laminated on the expand tape 2 is divided along the modified layer 105. That is, by expanding the expand tape 2, the substrate 1 and the adhesive layer 4 are integrally divided.

[0064] As described above, also in the second embodiment, before the chip interval expansion step and after the modified layer formation step, in the adhesion step, the expand tape 2 is made to adhere to the substrate 1. Therefore, in the chip interval expansion step, when the expand tape 2 is expanded, it is possible to preferably divide the substrate 1 starting from the modified layer 105 to preferably form a plurality of chips 107, and to preferably widen the interval 109 between the plurality of chips 107.

[0065] Also, in the second embodiment, in the adhesion step, with the expand tape 2 supported by the second support table 62, the roller 130 is rolled on the substrate 1. Therefore, similar to the adhesion step in the first embodiment, the expand tape 2 can be easily adhered to the substrate 1.

[0066] In the first and second embodiments, the adhesion step is performed in the laser processing apparatus 13 using the second support table 62 and the roller 130. In this regard, the adhesion step may be performed in the expander 14 using a support table and a roller for the adhesion step (not shown). Alternatively, the adhesion step may be performed by an independent adhesion apparatus (not shown) provided with a support table and a roller, which is separate from the laser processing apparatus 13 and the expander 14.

[0067] Also, in the chip interval expansion step, instead of expanding the expand tape 2 by the pushing member 9, the contact surface 21 of the expand tape 2 may be supported by a columnar expansion drum (not shown), and the expand tape 2 may be pushed up and expanded from below by raising this expansion drum.

[0068] Furthermore, the substrate dividing method shown in the first and second embodiments may include a grinding step performed before the expand tape attaching step. This grinding step is performed by the grinding apparatus 15 shown in FIG. 9. The grinding apparatus 15 includes a grinding mechanism 8 and a chuck table 69. In the grinding step, the back surface 11 of the substrate 1 held by the chuck table 69 is ground to a finish thickness by the grinding mechanism 8.

[0069] The grinding mechanism 8 includes a spindle 80, a spindle motor 82 that rotates the spindle 80 about a rotation axis 85 in the Z-axis direction, a mount 83 disposed at the lower end of the spindle 80, and a grinding wheel 84 attached to the mount 83. The grinding wheel 84 includes a wheel base 841 and a plurality of substantially rectangular parallelepiped grinding wheels 840 arranged annularly on the lower surface of the wheel base 841. The grinding wheel 840 is, for example, a finish grinding wheel.

[0070] The grinding mechanism 8 is connected to a lifting mechanism (not shown), and can be lifted and lowered in the Z-axis direction by this lifting mechanism. The upper surface of the chuck table 69 is a holding surface 690 for holding the substrate 1. The chuck table 69 is connected to a rotation mechanism (not shown) and can rotate about a rotation axis 65 in the Z-axis direction passing through the center of the holding surface 690.

[0071] When grinding the back surface 11 of the substrate 1 by the grinding mechanism 8, the substrate 1 is placed on the holding surface 690 of the chuck table 69 with the protective sheet 5 attached to its front surface 10 facing downward. Then, the surface 50 of the protective sheet 5 is sucked by a suction source (not shown) connected to the holding surface 690. Thereby, the chuck table 69 sucks and holds the substrate 1 via the protective sheet 5 by the holding surface 690.

[0072] Next, the chuck table 69 is rotated about the rotation axis 65 in the Z-axis direction by a rotation mechanism (not shown) to rotate the substrate 1 held by the chuck table 69. Also, the grinding wheel 840 is rotated about the rotation axis 85 by the spindle motor 82. In this state, the grinding wheel 840 is lowered in the -Z direction by a lifting mechanism (not shown), so that the lower surface 842 of the grinding wheel 840 contacts the back surface 11 of the substrate 1 and grinds this back surface 11. During the grinding of the substrate 1 by the grinding mechanism 8, for example, the thickness of the substrate 1 is measured by a thickness measuring mechanism (not shown), and when the back surface 11 of the substrate 1 is ground to the finish thickness, the grinding is terminated.

Explanation of Reference Numerals

[0073] 1: Substrate 10: Surface 11: Back surface 100: Predetermined division line 101: Device 105: Modified layer 107: Chip 109: Interval between chips 2: Expandable tape 20: Adhesive surface 21: Contact surface 3: Annular frame 30: Opening 4: Adhesive layer 5: Protective sheet 50: Surface 19: Work set 61: First support table 62: Second support table 63: Holding table 64: Frame holding unit 65: Rotation axis 69: Chuck table 610: Support surface 620: Support surface 628: Frame fixing unit 644: Shaft portion 648: Clamping clamp 690: Holding surface 7: Irradiation head 70: Laser beam 700: Focus point 8: Grinding mechanism 80: Spindle 82: Spindle motor 83: Mount 84: Grinding wheel 841: Wheel base 840: Grinding wheel 842: Bottom surface 85: Rotation axis 9: Pushing member 90: Roller member 12: Expandable tape sticking device 13: Laser processing device 14: Expander 15: Grinding device 120: Roller 130: Roller

Claims

1. A method for dividing a substrate along a planned division line, comprising: an expandable tape attaching step of attaching an expandable tape to the back surface of the substrate; after the expandable tape attaching step, irradiating a laser beam having a wavelength that is transmissive to the substrate along the planned division line with the focus point positioned inside the substrate to form a modified layer serving as a starting point for division inside the substrate, a modified layer forming step; after the modified layer forming step, expanding the expandable tape to widen the intervals formed between a plurality of chips starting from the modified layer, a chip interval widening step; and further comprising a close contact step of bringing the expandable tape into close contact with the substrate after the modified layer forming step and before the chip interval widening step. A method for dividing a substrate.

2. In the close contact step, a roller is rolled on either one of the substrate or the expandable tape while the other is supported by a support table. The method for dividing a substrate according to Claim 1.

3. An adhesive layer is laminated on the expandable tape. In the chip interval widening step, the adhesive layer is divided along the modified layer. The method for dividing a substrate according to Claim 1.

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