Method for dividing a workpiece and method for manufacturing a device chip

Abstract

To provide a method for dividing a workpiece and a method for manufacturing device chips that can divide the workpiece with greater precision than conventional methods, and that can suppress the risk of chipping due to collisions between device chips. [Solution] A method for dividing a workpiece that has multiple intersecting division lines set comprises: an attachment step 1001 of attaching an expanded sheet to the workpiece; a modified layer formation step 1002 of focusing a laser beam of a wavelength that is transparent to the workpiece into the workpiece to form a modified layer along the division lines; an expansion step 1003 of fixing the expanded sheet in an expanded state after the modified layer formation step 1002; and a division step 1004 of applying an external force to the workpiece after the expansion step 1003 to divide the workpiece along the division lines starting from the modified layer.

Description

Technical Field

[0001] The present invention relates to a method for dividing a workpiece and a method for manufacturing a device chip.

Background Art

[0002] As a method for processing a workpiece such as a wafer, a laser beam having a wavelength that is transparent to the workpiece is irradiated to form a modified layer inside the workpiece, and then an external force is applied to the workpiece to divide the workpiece into individual device chips starting from the modified layer (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the workpiece is a wafer of a non-crystalline material such as glass, cracks may meander from the modified layer instead of extending linearly. For example, when trying to expand an expand sheet attached to the workpiece and divide it starting from the modified layer, there are problems such as inaccurate division or undivided regions remaining.

[0005] Therefore, when dividing a non-crystalline workpiece, after forming a modified layer inside the workpiece, a method of directly pressing a breaking blade against the region where the modified layer of the workpiece is formed is used for division. However, in the case of the division method by breaking, since the gap between the divided device chips is small, another problem has occurred in that the device chips collide with each other and chipping occurs.

[0006] This invention has been made in view of the above problems, and its purpose is to provide a method for dividing a workpiece and a method for manufacturing device chips that can divide the workpiece with greater precision than conventional methods and suppress the risk of chipping due to collisions between device chips. [Means for solving the problem]

[0007] To solve the above-mentioned problems and achieve the objective, the present invention provides a method for dividing a workpiece, which divides a workpiece on which a plurality of intersecting division lines have been set, comprising: an attachment step of attaching an expanded sheet to the workpiece; a modified layer formation step of focusing a laser beam of a wavelength that is transparent to the workpiece into the workpiece to form a modified layer along the division lines; an expansion step of fixing the expanded sheet in an expanded state after the modified layer formation step; and a division step of applying an external force to the workpiece after the expansion step to divide the workpiece along the division lines starting from the modified layer.

[0008] The splitting step may also be performed by pressing the workpiece with a pressing means to split it.

[0009] The process may further include a workpiece unit forming step, in which the expanded sheet is sandwiched between the outer circumference of the inner ring and the inner circumference of the outer ring, thereby forming a workpiece unit in which the workpiece, the inner ring, and the outer ring are integrated via the expanded sheet.

[0010] The workpiece may be amorphous.

[0011] The workpiece may include a sapphire substrate, a garnet substrate, or a ceramic substrate.

[0012] To solve the above-mentioned problems and achieve the objective, the present invention provides a method for manufacturing a device chip, which involves manufacturing a device chip using the method for dividing a workpiece described in claim 1, on a workpiece in which a device is formed in a region partitioned by a plurality of intersecting division lines on the surface. [Effects of the Invention]

[0013] In this invention, an expansion step is performed to expand an expandable sheet before the division step of dividing the workpiece, and the workpiece is divided by performing the division step while the expandable sheet is expanded. Therefore, in this invention, at the moment the device chips are separated from the workpiece, they are pulled by the expanded sheet, creating a suitable gap of roughly the same size between all the device chips. As a result, this invention can divide with greater precision than conventional methods and suppress the risk of chipping due to collisions between device chips. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a flowchart showing the processing procedure for the workpiece division method according to Embodiment 1. [Figure 2] Figure 2 is a perspective view illustrating the adhesion step in Figure 1. [Figure 3] Figure 3 is a cross-sectional view illustrating the modified layer formation step in Figure 1. [Figure 4] Figure 4 is a cross-sectional view illustrating the extended steps of Figure 1. [Figure 5] Figure 5 is a cross-sectional view illustrating the division steps in Figure 1. [Figure 6] Figure 6 is a flowchart showing the processing procedure for the workpiece division method according to Embodiment 2. [Figure 7] Figure 7 is a cross-sectional view illustrating the workpiece unit formation step shown in Figure 6. [Figure 8] Figure 8 is a cross-sectional view illustrating the workpiece unit formation step shown in Figure 6. [Figure 9]FIG. 9 is a cross-sectional view for explaining the workpiece unit forming step of FIG. 6. [Figure 10] FIG. 10 is a cross-sectional view for explaining the dividing step of FIG. 6. [Figure 11] FIG. 11 is a diagram for explaining the operation and effect of the workpiece dividing method and the device chip manufacturing method according to Embodiment 1.

MODE FOR CARRYING OUT THE INVENTION

[0015] The embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the content described in the following embodiments. Further, the constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Also, various omissions, substitutions, or changes in the configuration can be made without departing from the gist of the present invention.

[0016] 〔Embodiment 1〕 The workpiece dividing method and the device chip manufacturing method according to Embodiment 1 of the present invention will be described based on the drawings. FIG. 1 is a flowchart showing the processing procedure of the workpiece dividing method according to Embodiment 1. FIG. 2 is a perspective view for explaining the sticking step 1001 of FIG. 1. The workpiece dividing method according to Embodiment 1 is a method for dividing the workpiece 100 shown in FIG. 2. As shown in FIG. 1, it includes a sticking step 1001, a modified layer forming step 1002, an expansion step 1003, and a dividing step 1004. The device chip manufacturing method according to Embodiment 1 is a method for manufacturing the device chip 130 (see FIG. 5) on the workpiece 100 shown in FIG. 2 using the workpiece dividing method according to Embodiment 1.

[0017] In Embodiment 1, the workpiece 100 is a wafer (substrate) such as a disk-shaped semiconductor wafer or an optical device wafer made of a material in which cracks hardly extend linearly from a modified layer 120 (see FIGS. 3, 4, and 5) formed in a subsequent modified layer formation step 1002. Materials in which cracks hardly extend linearly from the modified layer 120 are, for example, non-crystals such as glass in which cracks may meander, and sapphire, garnet, ceramics, etc. in which cracks hardly extend. For this reason, the workpiece 100 includes a glass substrate (non-crystal substrate) made of a non-crystal such as glass as a base material, a sapphire substrate made of sapphire as a base material, a garnet substrate made of garnet as a base material, and a ceramic substrate made of ceramics as a base material, etc.

[0018] As shown in FIG. 2, on the flat surface 101 of the workpiece 100, a plurality of division planned lines 102 that intersect (orthogonal in Embodiment 1) are set. In the workpiece 100, devices 103 are formed in regions partitioned by the plurality of division planned lines 102 that intersect (orthogonal) on the surface 101.

[0019] As shown in FIG. 2, the sticking step 1001 is a step of sticking an expand sheet 110 to the workpiece 100. In the sticking step 1001, as shown in FIG. 2, the expand sheet 110 is stuck to the other surface on the opposite side of the surface of the workpiece 100 to be irradiated with the laser beam 15 in the subsequent modified layer formation step 1002, and an annular frame 111 is attached to the outer edge of the expand sheet 110. In Embodiment 1, the sticking step 1001 sticks the expand sheet 110 to the back surface 104 on the back side of the surface 101 of the workpiece 100, but the present invention is not limited to this, and the expand sheet 110 may be stuck to the surface 101 of the workpiece 100.

[0020] The expanded sheet 110 used in the bonding step 1001 is a base sheet made of an elastic resin with an adhesive layer formed on one side. The other side of the workpiece 100 is bonded to the side with the adhesive layer, thereby supporting the workpiece 100 from the other side. The annular frame 111 used in the bonding step 1001 has a circular opening in the center that is larger than the outer diameter of the workpiece 100, and is formed in a plate shape.

[0021] Figure 3 is a cross-sectional view illustrating the modified layer formation step 1002 of Figure 1. As shown in Figure 3, the modified layer formation step 1002 is a step in which a laser beam 15 with a wavelength that is transparent to the workpiece 100 is focused into the workpiece 100 to form a modified layer 120 along the division line 102. Here, the modified layer 120 refers to a region in which the density, refractive index, mechanical strength, and other physical properties are in a state different from those of the surrounding area, and examples include a melted region, a cracked region, a dielectric breakdown region, a refractive index change region, and a region in which these regions are mixed.

[0022] In Embodiment 1, the modified layer formation step 1002 is carried out using a laser processing apparatus 10, as shown in Figure 3. The laser processing apparatus 10 includes a laser irradiator 11 that irradiates the workpiece 100 with a laser beam 15 of a wavelength that is penetrating to the workpiece 100 from one side of the workpiece 100, a holding table 12 that holds the workpiece 100 from the other side, a moving unit (not shown) that moves the laser irradiator 11 and the holding table 12 relative to each other, and a control unit (computer system) (not shown) that controls the laser irradiator 11, the holding table 12, and the moving unit.

[0023] In the modified layer formation step 1002, first, as shown in Figure 3, the other side of the workpiece 100 is held by the holding table 12 via the expanded sheet 110. Next, the focusing point 16 of the laser beam 15 irradiated from the laser irradiator 11 is set to a predetermined depth 121 from one side of the interior of the workpiece 100 held on the holding table 12. Then, while irradiating the workpiece 100 with the laser beam 15 from one side of the workpiece 100 using the laser irradiator 11, the moving unit moves the laser irradiator 11 and the holding table 12 relative to each other along an arbitrary planned division line 102 of the workpiece 100 on the holding table 12. As a result, laser processing is performed along the planned division line 102 at a depth 121 inside the workpiece 100, forming the modified layer 120.

[0024] In the modified layer formation step 1002, laser processing is performed in the same manner along all planned division lines 102 at a depth 121 inside the workpiece 100 to form a modified layer 120.

[0025] In the modified layer formation step 1002, the focusing point 16 of the laser beam 15 irradiated from the laser irradiator 11 is set to a predetermined depth 122 on one side of the inside of the workpiece 100 held on the holding table 12, and in the same manner, laser processing is performed along all planned division lines 102 at a depth 122 inside the workpiece 100 to form the modified layer 120.

[0026] In the modified layer formation step 1002, in the example of Embodiment 1 shown in Figure 3, the modified layer 120 is formed at multiple different depths 121 and 122. In Embodiment 1, the workpiece 100 is a glass substrate (amorphous substrate), a sapphire substrate, a garnet substrate, and a ceramic substrate, so cracks are unlikely to extend linearly from the modified layer 120 formed in the modified layer formation step 1002. Therefore, the multiple modified layers 120 arranged along the depth direction formed in this way are unlikely to connect in the depth direction even through cracks, so even if the expanded sheet 110 is expanded by subsequently performing the expansion step 1003, it will not become a dividing point that splits the workpiece 100.

[0027] The multiple modified layers 120 arranged along the depth direction, formed in this manner, can only be further connected in the depth direction by performing a splitting step 1004 to apply an external force to the workpiece 100, thereby enabling the workpiece 100 to be split so that the split surface is preferably aligned along the depth direction. It should be noted that the present invention is not limited to the embodiment 1 shown in Figure 3, in which modified layers 120 are formed at two different depths 121 and 122. Modified layers 120 may be formed at one depth, or at three or more different depths.

[0028] Figure 4 is a cross-sectional view illustrating the expansion step 1003 of Figure 1. The expansion step 1003 is a step in which the expanded sheet 110 is fixed in an expanded state after the modified layer formation step 1002.

[0029] In the expansion step 1003, in Embodiment 1, the expansion is carried out using the expansion device 20, as shown in Figure 4. The expansion device 20, as shown in Figure 4, includes a frame fixing part 21, a push-up member 22, a lifting unit (not shown), and a control unit (computer system) (not shown) that controls the frame fixing part 21, the push-up member 22, and the lifting unit.

[0030] The frame fixing portion 21 includes a frame support portion that supports the annular frame 111 from below and a frame pressing portion that presses the annular frame 111 from above. Both the frame support portion and the frame pressing portion of the frame fixing portion 21 have openings that are larger than the inner diameter of the opening of the annular frame 111.

[0031] The thrusting member 22 is formed in a cylindrical shape that is larger than the outer diameter of the workpiece 100 and smaller than the inner diameter of the opening of the annular frame 111. The thrusting member 22 is provided on the inner circumference and coaxially with the opening of the frame fixing part 21. The thrusting member 22 may have a plurality of expansion rollers (not shown) arranged in an annular pattern at its upper end, each rotatable around a rotation axis along the circumferential direction of the thrusting member 22. The lifting unit is provided connected below the thrusting member 22 and raises the thrusting member 22 relative to the frame fixing part 21.

[0032] In expansion step 1003, first, as shown in Figure 4, the annular frame 111 attached to the workpiece 100 is fixed by the frame fixing part 21, and the workpiece 100 is positioned coaxially with the frame fixing part 21 and the push-up member 22. Next, the push-up member 22 is raised relative to the frame fixing part 21 that fixes the annular frame 111 by the lifting unit. As a result, the upper surface of the push-up member 22 presses the annular region between the outer circumference of the workpiece 100 and the inner circumference of the opening of the annular frame 111 in the thickness direction of the workpiece 100 in the expanded sheet 110 attached to the workpiece 100, thereby expanding the expanded sheet 110 in a generally isotropic manner in the surface direction.

[0033] In expansion step 1003, as shown in Figure 4, the expandable sheet 110 can be fixed in a state where it is expanded approximately isotropically in the planar direction by fixing the push-up member 22 in a raised position relative to the frame fixing part 21.

[0034] As described above, in Embodiment 1, cracks are unlikely to extend linearly from the modified layer 120 formed in the modified layer formation step 1002 of the workpiece 100. Therefore, even if cracks form in the modified layer 120, they are unlikely to connect in the depth direction. Thus, even if the expanded sheet 110 is expanded by performing the expansion step 1003, the state in which the workpiece is not divided starting from the modified layer 120 is maintained.

[0035] Figure 5 is a cross-sectional view illustrating the splitting step 1004 of Figure 1. As shown in Figure 5, the splitting step 1004 is a step in which an external force is applied to the workpiece 100 after the expansion step 1003 to split the workpiece 100 along the planned splitting line 102, starting from the modified layer 120. In Embodiment 1, the splitting step 1004 is carried out using a splitting device 30, as shown in Figure 5, and the workpiece 100 is pressed and split by the braking blade 31 of the splitting device 30. The braking blade 31 is an example of a pressing means in the present invention, and the pressing force applied to the workpiece 100 by the braking blade 31 is an example of an external force applied to the workpiece 100 in the present invention.

[0036] As shown in Figure 5, the splitting device 30 includes a braking blade 31, a pair of support plates 32, a moving unit (not shown) for moving the braking blade 31 and the pair of support plates 32 relative to each other, and a control unit (computer system) (not shown) for controlling the braking blade 31, the pair of support plates 32, and the moving unit.

[0037] The braking blade 31 is formed to extend in one direction parallel to the horizontal (a direction perpendicular to the plane of the paper in Figure 5), and has a blade-shaped tip that extends downward in that direction. The pair of support plates 32 extend in the same direction as the braking blade 31, and are provided parallel to each other at a predetermined distance apart in a direction parallel to the horizontal and perpendicular to that direction. The braking blade 31 and the pair of support plates 32 are positioned such that the tip of the braking blade 31 is directed towards the center of the predetermined distance between the pair of support plates 32. The moving unit supports the braking blade 31 from above so that it can move freely along the vertical direction. The moving unit moves the braking blade 31 up and down along the vertical direction.

[0038] The splitting step 1004 is performed with the expanded sheet 110 fixed in the expanded state in the planar direction in the expansion step 1003, as shown in Figure 5. In the splitting step 1004, first, the pair of support plates 32 are positioned below the workpiece 100, which is fixed with the expanded sheet 110 expanded in the planar direction, parallel to any planned splitting line 102 of the workpiece 100, and straddling the planned splitting line 102 exactly in the center. Next in the splitting step 1004, the braking blade 31 is lowered by the moving unit so that the tip of the braking blade 31 contacts the planned splitting line 102 of the workpiece 100 supported by the pair of support plates 32. In the splitting step 1004, the moving unit further lowers the braking blade 31, pressing the workpiece 100 along the planned splitting line 102 with the tip of the braking blade 31, thereby applying bending stress to the workpiece 100 along the planned splitting line 102. As a result, the tip of the braking blade 31 splits the workpiece 100 along the planned splitting line 102, starting from the modified layer 120 formed along the planned splitting line 102 on the workpiece 100.

[0039] In the splitting step 1004, the tip of the braking blade 31 similarly splits along all the planned splitting lines 102. In this way, each device 103 formed on the workpiece 100 is split into individual chips to manufacture the device chips 130.

[0040] In this invention, the splitting step 1004 is not limited to the embodiment 1 shown in Figure 5, in which the workpiece 100 is split by pressing it with the braking blade 31 of the splitting device 30. For example, as described below, the workpiece 100 may be split by pressing it with a pressing roller. The pressing roller is an example of a pressing means in this invention, and the pressing force applied to the workpiece 100 by the pressing roller is an example of an external force applied to the workpiece 100 in this invention.

[0041] Specifically, first, the workpiece 100, which has been fixed in the expanded sheet 110 in the planar direction in the expansion step 1003, is held from below by a holding table that has an elastic member. Here, the material constituting the elastic member is a material that elastically deforms in response to being pressed through the workpiece 100 by the pressing roller and generates a repulsive force (elastic force) in the direction of the pressure, such as rubber or sponge.

[0042] Next, the workpiece 100, which is held by a holding table having an elastic member, is rotated from one end to the other while the pressing roller is pressed from above to below. This applies pressing force from the pressing roller to the workpiece 100, and the elastic force generated in the elastic member of the holding table by the pressing roller is applied to the workpiece 100, thereby applying external force to the workpiece 100 from both the front surface 101 and the back surface 104, and dividing the workpiece 100 along all the planned division lines 102 starting from the modified layer 120.

[0043] Thus, since the workpiece 100 is divided by performing the splitting step 1004 while the expanded sheet 110 is fixed in the expanded state in the planar direction after the expansion step 1003, at the moment the device chips 130 are separated from the workpiece 100, they are pulled by the expanded sheet 110, which is expanded approximately isotropically, and a moderate gap 131 (see Figure 5) of roughly the same size can be formed between all the device chips 130. In Embodiment 1, the gap 131 formed between the device chips 130 after performing the splitting step 1004 is 250 μm or more and 300 μm or less.

[0044] In the method for dividing a workpiece and manufacturing a device chip according to Embodiment 1 having the above configuration, an expansion step 1003 is performed to expand the expand sheet 110 before performing the division step 1004 to divide the workpiece 100, and the division step 1004 is performed with the expand sheet 110 expanded to divide the workpiece 100. Therefore, in the method for dividing a workpiece and manufacturing a device chip according to Embodiment 1, at the moment the device chip 130 is divided from the workpiece 100, it is pulled by the expanded expand sheet 110, and an appropriate gap 131 of roughly the same size is formed between all the device chips 130. As a result, the method for dividing a workpiece and manufacturing a device chip according to Embodiment 1 has the effect of being able to divide with higher precision than conventional methods, and suppressing the risk of chipping occurring due to collisions between the device chips 130.

[0045] Furthermore, in the workpiece division method and device chip manufacturing method according to Embodiment 1, in the division step 1004, the workpiece 100 is divided by pressing it with a pressing means (braking blade 31 or pressing roller). Therefore, the workpiece division method and device chip manufacturing method according to Embodiment 1 can more preferably realize the process of dividing the workpiece 100 while the expanded sheet 110 is expanded. Consequently, the workpiece division method and device chip manufacturing method according to Embodiment 1 can more preferably achieve division with higher precision than conventional methods, and can also suppress the risk of chipping occurring due to collisions between device chips 130.

[0046] Furthermore, the workpiece division method and device chip manufacturing method according to Embodiment 1 are applicable to workpieces 100 such as glass substrates (amorphous substrates), sapphire substrates, garnet substrates, and ceramic substrates. Therefore, in the workpiece division method and device chip manufacturing method according to Embodiment 1, cracks are less likely to extend linearly from the modified layer 120 formed in the modified layer formation step 1002, and the modified layer 120 is less likely to connect in the depth direction even if cracks are present. As a result, even when the expanded sheet 110 is expanded by performing the expansion step 1003, the workpiece can maintain a state where it is not divided starting from the modified layer 120. Thus, the workpiece division method and device chip manufacturing method according to Embodiment 1 can more stably achieve the process of dividing the workpiece 100 while the expanded sheet 110 is expanded. Therefore, the method for dividing a workpiece and the method for manufacturing a device chip according to Embodiment 1 can achieve the effect of dividing the workpiece more stably and with greater precision than conventional methods, as well as suppressing the risk of chipping due to collisions between device chips 130.

[0047] [Embodiment 2] A method for dividing a workpiece and a method for manufacturing a device chip according to Embodiment 2 of the present invention will be described with reference to the drawings. Figure 6 is a flowchart showing the processing procedure for the workpiece division method according to Embodiment 2. Figures 7, 8, and 9 are cross-sectional views illustrating the workpiece unit formation step 1005 of Figure 6. Figure 10 is a cross-sectional view illustrating the division step 1004 of Figure 6. Figures 6 to 10 use the same reference numerals as Embodiment 1, and their descriptions are omitted.

[0048] The method for dividing a workpiece according to Embodiment 2, as shown in Figure 6, is a modification of the method for dividing a workpiece according to Embodiment 1, further comprising a workpiece unit formation step 1005 after the expansion step 1003 and before the division step 1004, with the expansion step 1003 and division step 1004 modified accordingly, while the other configurations are the same as in Embodiment 1. The method for manufacturing a device chip according to Embodiment 2 is a method for manufacturing a device chip 130 using the method for dividing a workpiece according to Embodiment 2 on a workpiece 100 shown in Figure 2, and is a modification of the method for manufacturing a device chip according to Embodiment 1, further comprising a workpiece unit formation step 1005, while the other configurations are the same as in Embodiment 1.

[0049] In Embodiment 2, the expansion step 1003 is modified from Embodiment 1 to include the installation of an annular inner ring 140 on the upper surface of the push-up member 22, as shown in Figure 7, while the other configurations are the same as in Embodiment 1. In the expansion step 1003, in Embodiment 2, the annular region of the expanded sheet 110 attached to the workpiece 100 is pressed in the thickness direction of the workpiece 100 with the upward-facing side of the inner ring 140 installed on the upper surface of the push-up member 22, thereby expanding the expanded sheet 110 in a generally isotropic manner in the surface direction.

[0050] The inner ring 140 used in the expansion step 1003 of Embodiment 2 is an annular member having the same outer and inner diameters as the push-up member 22. The inner ring 140 has both ends in the axial direction perpendicular to the axial direction and is formed in a flat, annular shape when viewed from above. The inner ring 140 has an inner circumferential portion (inner surface) that is parallel to the axial direction on the inner circumference side and an outer circumferential portion 141 (outer surface) that is parallel to the axial direction on the outer circumference side.

[0051] In the expansion step 1003 of Embodiment 2, the inner ring 140 is supported from below by the upper surface of the push-up member 22, with its downward-facing lower surface facing downward, and is pushed upward, pressing the annular region of the expanded sheet 110 attached to the workpiece 100 with its upward-facing upper surface.

[0052] The workpiece unit formation step 1005 is a step in which, as shown in Figures 7, 8, and 9, the expanded sheet 110 expanded in the expansion step 1003 is sandwiched between the outer circumference 141 of the inner ring 140 and the inner circumference 151 of the outer ring 150, thereby forming a workpiece unit 200 in which the workpiece 100, the inner ring 140, and the outer ring 150 are integrated via the expanded sheet 110.

[0053] The outer ring 150 used in the workpiece unit formation step 1005 is a ring-shaped member, similar to the inner ring 140. The inner diameter of the outer ring 150 is formed to be slightly larger than the outer diameter of the inner ring 140, for example, by the thickness of the expanded sheet 110, and is formed to be sized to fit onto the outer circumference of the inner ring 140 via the expanded sheet 110. The outer ring 150 has both ends in the axial direction perpendicular to the axial direction and is formed in a flat, ring-shaped plane when viewed from above. The outer ring 150 has an inner circumferential portion 151 (inner surface) formed on the inner circumference side that is parallel to the axial direction, and an outer surface (outer surface) formed on the outer circumference side that is parallel to the axial direction.

[0054] In the workpiece unit formation step 1005, first, as shown in Figure 7, the outer ring 150 is positioned on the opposite side and coaxially with the inner ring 140 used in the expansion step 1003 relative to the expanded sheet 110 in its expanded state. Next, in the workpiece unit formation step 1005, the outer ring 150 is brought closer to the inner ring 140 and the expanded sheet 110 along the axial direction, and is brought into contact with the expanded sheet 110 in its expanded state.

[0055] In the workpiece unit formation step 1005, the outer ring 150 is moved further toward the inner ring 140, so that, as shown in Figure 8, the expanded sheet 110 is bent upward in a convex direction at the corner between the upper surface and the outer circumference 141 of the inner ring 140. Then, the area of ​​the expanded sheet 110 immediately toward the outer circumference 141 of the inner ring 140 is sandwiched between the outer circumference 141 of the inner ring 140 and the inner circumference 151 of the outer ring 150, and the outer ring 150 is fitted to the outer circumference of the inner ring 140 via the expanded sheet 110.

[0056] In the workpiece unit formation step 1005, the expanded sheet 110 is sandwiched between the outer circumference 141 of the inner ring 140 and the inner circumference 151 of the outer ring 150, and the outer ring 150 is fitted to the outer circumference side of the inner ring 140 via the expanded sheet 110. As a result, the inner ring 140 and the outer ring 150 can maintain and fix the area of ​​the expanded sheet 110 on the inner circumference side of the sandwiched area.

[0057] In the workpiece unit formation step 1005, the expanded sheet 110 is sandwiched between the outer circumference 141 of the inner ring 140 and the inner circumference 151 of the outer ring 150, and then the workpiece 100, expanded sheet 110, and annular frame 111 are removed from the expansion device 20 together with the inner ring 140 and the outer ring 150. Even after being removed from the expansion device 20 in this way, the area on the inner circumference side of the sandwiched area of ​​the expanded sheet 110 is maintained and fixed in an expanded state by the inner ring 140 and the outer ring 150. On the other hand, the area on the outer circumference side of the sandwiched area of ​​the expanded sheet 110 is removed from the expansion device 20, and the expanded state created by the expansion device 20 is resolved.

[0058] In the workpiece unit formation step 1005, as shown in Figure 9, the excess region, which is the region on the outer circumference side of the region sandwiched by the expanded sheet 110, is removed. In Embodiment 2, the excess region is separated from the region on the inner circumference side of the region sandwiched by the expanded sheet 110 by cutting the expanded sheet 110 along the lower surfaces of the inner ring 140 and the outer ring 150 with a cutter or the like. As a result, as shown in Figure 9, a workpiece unit 200 is formed in which the workpiece 100, the inner ring 140 and the outer ring 150 are integrated via the expanded sheet 110.

[0059] As shown in Figure 9, the workpiece unit 200 formed in the workpiece unit formation step 1005 is formed with the expanded sheet 110 attached to the back surface 104 of the workpiece 100 in an expanded state, and the outer peripheral edge of the expanded sheet 110 is sandwiched between the outer peripheral portion 141 of the inner ring 140 and the inner peripheral portion 151 of the outer ring 150.

[0060] In Embodiment 2, the splitting step 1004 is modified as shown in Figure 10. Instead of splitting the workpiece 100 with the expanded sheet 110 expanded by the expansion device 20 as in Embodiment 1, the workpiece 100 is split with the expanded sheet 110 expanded by the inner ring 140 and the outer ring 150. The other configurations are the same as in Embodiment 1. That is, in Embodiment 2, the splitting step 1004, as shown in Figure 10, splits the workpiece 100 that constitutes the workpiece unit 200 formed in the workpiece unit formation step 1005.

[0061] In Embodiment 2, the splitting step 1004 is performed by holding the workpiece unit 200 from below with a cylindrical holding unit 33, as shown in Figure 10. The holding unit 33 used in the splitting step 1004 of Embodiment 2 has an upper surface that is annular in shape when viewed from above, and is formed as a flat plane. The inner diameter of the holding unit 33 is formed to be slightly smaller than the inner diameter of the inner ring 140, and the outer diameter is formed to be slightly larger than the outer diameter of the outer ring 150. Therefore, in the splitting step 1004, in Embodiment 2, first, the inner ring 140 and outer ring 150 of the workpiece unit 200 are positioned above and coaxially with the holding unit 33 and placed on the upper surface of the holding unit 33.

[0062] In the splitting step 1004, in Embodiment 2, an external force is then applied to the workpiece 100 of the workpiece unit 200, which is held from below by the holding unit 33, in the same manner as in Embodiment 1, to split the workpiece 100 along the planned splitting line 102, starting from the modified layer 120. In the example of Embodiment 2 shown in Figure 10, the workpiece 100 is split by pressing with the braking blade 31, similar to the example of Embodiment 1 shown in Figure 5, but the present invention is not limited to this, and the workpiece 100 may also be split by pressing with a pressing roller as described above.

[0063] The method for dividing a workpiece and manufacturing a device chip according to Embodiment 2, having the configuration described above, is similar to Embodiment 1 in that an expansion step 1003 is performed to expand the expand sheet 110 before performing the dividing step 1004 to divide the workpiece 100, and the dividing step 1004 is performed with the expand sheet 110 expanded to divide the workpiece 100. Therefore, the method for dividing a workpiece and manufacturing a device chip according to Embodiment 2 will have the same effects as Embodiment 1.

[0064] The method for dividing a workpiece and manufacturing a device chip according to Embodiment 2 is a modification of Embodiment 1, further comprising a workpiece unit forming step 1005, in which the expanded expanded sheet 110 is sandwiched between the outer circumference 141 of the inner ring 140 and the inner circumference 151 of the outer ring 150, after the expansion step 1003 and before the dividing step 1004, thereby forming a workpiece unit 200 in which the workpiece 100, the inner ring 140 and the outer ring 150 are integrated via the expanded expanded sheet 110. In this way, the method for dividing a workpiece and manufacturing a device chip according to Embodiment 2 allows the expanded sheet 110 to be fixed in an expanded state by being sandwiched between the inner ring 140 and the outer ring 150, instead of fixing the expanded sheet 110 in an expanded state by the expansion device 20 that performed the expansion step 1003 in Embodiment 1. Therefore, the method for dividing a workpiece and manufacturing a device chip according to Embodiment 2 makes it easier to handle the expanded sheet 110 while it is fixed in an expanded state, compared to Embodiment 1. This allows for easier and more accurate division than conventional methods, and also reduces the risk of chipping due to collisions between device chips 130.

[0065] [Examples] Next, the inventors of the present invention confirmed the effects of the workpiece division method and device chip manufacturing method according to Embodiment 1. Figure 11 is a diagram illustrating the effects of the workpiece division method and device chip manufacturing method according to Embodiment 1. Figure 11 summarizes the results obtained when confirming the effects.

[0066] The "Comparative Example" column on the left side of Figure 11 shows the state of the workpiece 100 after the formation of the modified layer 120 and after the workpiece 100 is divided (images taken from the surface 101 side) when a conventional workpiece division method and device chip manufacturing method is performed, which only involves attaching the expanded sheet 110, forming the modified layer 120, and dividing the workpiece 100 by applying external force, without performing the extended step 1003 of the workpiece division method and device chip manufacturing method according to Embodiment 1. The "Examples" column on the right side of Figure 11 shows the state of the workpiece 100 after the formation of the modified layer 120 and after the division (images taken from the surface 101 side) when the workpiece division method and device chip manufacturing method according to Embodiment 1 is carried out, which includes an expansion step 1003 (labeled "Expand" in Figure 11), and involves attaching the expanded sheet 110, forming the modified layer 120, expanding the expanded sheet 110 with the expansion device 20, and dividing the workpiece 100 by applying external force while the expanded sheet 110 is expanded with the expansion device 20. In the "Comparative Examples" and "Examples," a glass substrate (amorphous substrate) with an amorphous material such as glass as the base material was used as the workpiece 100.

[0067] As shown in Figure 11, when a conventional method of dividing a workpiece and manufacturing a device chip according to Embodiment 1 was performed without the expansion step 1003, it was observed that almost no gaps 131 were formed between the device chips 130 from the time the modified layer 120 was formed until after division. On the other hand, when the method of dividing a workpiece and manufacturing a device chip according to Embodiment 1, including the expansion step 1003 by the expansion device 20, was performed, it was observed that a similarly appropriate gap 131 was formed between all the device chips 130 from the time the modified layer 120 was formed until after division. Specifically, the gap 131 between the device chips 130 formed in the "Comparative Example" was 20 μm, while the gap 131 between the device chips 130 formed in the "Example" was 260 μm. As a result, in the embodiment shown in Figure 11, by performing the expansion step 1003 with the expansion device 20 and applying an external force to divide the workpiece 100 while the expanded sheet 110 is expanded by the expansion device 20, it became clear that at the moment the device chips 130 are separated from the workpiece 100, they are pulled by the expanded expanded sheet 110, forming a gap 131 of roughly the same size between the device chips 130.

[0068] Furthermore, Figure 11 shows "Comparative Examples" and "Examples" in which the workpiece 100 was a glass substrate with an amorphous material such as glass as the base material, but even when the same division process as in the "Comparative Examples" and "Examples" was performed on a sapphire substrate, a garnet substrate, and a ceramic substrate as the workpiece 100, the same results as the glass substrate examples shown in the "Comparative Examples" and "Examples" columns of Figure 11 were obtained. This revealed that, not only when the workpiece 100 is a glass substrate, but also when it is a sapphire substrate, a garnet substrate, or a ceramic substrate, by performing the expansion step 1003 with the expansion device 20 and applying external force while the expanded sheet 110 is expanded by the expansion device 20 to divide the workpiece 100, it is possible to form a similarly appropriate gap 131 between the device chips 130 at the moment the device chips 130 are separated from the workpiece 100, as they are pulled by the expanded expanded sheet 110.

[0069] Furthermore, Figure 11 shows an "Example" in which the workpiece 100 is divided by applying external force while the expanded sheet 110 is expanded by the expansion device 20. However, even when the workpiece division method and device chip manufacturing method according to Embodiment 2 is performed, in which the workpiece unit formation step 1005 is further performed after the expansion step 1003, and the workpiece 100 is divided by applying external force while the expanded sheet 110 is expanded by the inner ring 140 and outer ring 150, the result was obtained that, similar to the example shown in the "Example" column of Figure 11, a moderate gap 131 of roughly the same size is formed between all the device chips 130 from after the formation of the modified layer 120 to after division. This revealed that even when the workpiece unit formation step 1005 is performed after the expansion step 1003, and the workpiece 100 is divided by applying external force while the expanded sheet 110 is expanded by the inner ring 140 and outer ring 150, a similarly appropriate gap 131 can be formed between the device chips 130 at the moment the device chips 130 are separated from the workpiece 100, as they are pulled by the expanded expanded sheet 110.

[0070] It should be noted that the present invention is not limited to the embodiments described above. That is, it can be implemented with various modifications without departing from the core principles of the present invention. [Explanation of symbols]

[0071] 15 Laser beam 31 Braking Blade 100 Workpiece 102 planned division lines 103 devices 110 Expandable Sheet 120 Modified layer 130 device chips 140 Inner Ring 141 Outer perimeter 150 Outer Ring 151 Inner circumference 200 Workpiece Units 1001 Adhesion Step 1002 Modified layer formation step 1003 Extension Step 1004 division steps 1005 Workpiece unit formation step

Claims

1. A method for dividing a workpiece in which multiple intersecting division lines are set, The process includes an attachment step of attaching an expanded sheet to the workpiece, A modified layer formation step involves focusing a laser beam with a wavelength that is transparent to the workpiece into the workpiece to form a modified layer along the planned division line, Following the modified layer formation step, there is an expansion step in which the expanded sheet is fixed in an expanded state, Following the expansion step, a splitting step is performed in which an external force is applied to the workpiece to split it along the planned splitting line, starting from the modified layer. A method for dividing a workpiece, comprising the following components.

2. The method for dividing a workpiece according to claim 1, wherein the dividing step involves pressing the workpiece with a pressing means to divide it.

3. The method for dividing a workpiece according to claim 1, further comprising a workpiece unit forming step, in which, after the expansion step, the expanded expanded sheet is sandwiched between the outer circumference of the inner ring and the inner circumference of the outer ring, thereby forming a workpiece unit in which the workpiece, the inner ring and the outer ring are integrated via the expanded sheet.

4. The method for dividing a workpiece according to any one of claims 1 to 3, wherein the workpiece is amorphous.

5. A method for dividing a workpiece according to any one of claims 1 to 3, wherein the workpiece includes a sapphire substrate, a garnet substrate, and a ceramic substrate.

6. A method for manufacturing a device chip, in which a device is formed in a workpiece having a device formed in a region partitioned by multiple intersecting division lines on its surface, using the method for dividing a workpiece described in claim 1.

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