Division method

Abstract

To provide a division method which can be smoothly divided while suppressing a processing time and a cost.SOLUTION: A division method comprises: a first cutting step 101 of making a cutting blade to be rotated to be cut along a division schedule line from a front surface of a processed material, and forming a first cutting groove that is not achieved to a back surface of the processed material; a second cutting step 102 that makes the cutting blade to be rotated to be cut along the first cutting groove from the back surface of the processed material after the first cutting step 101, and forming a second cutting groove that is not achieved to a bottom part of the first cutting groove; and a division step 103 of applying an external force to the processed material, and dividing the processed material along the division schedule line after the second cutting step 102.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for dividing a substrate used for an optical device wafer or the like along planned dividing lines. [Background technology]

[0002] In general, optical device wafers made of sapphire, SiC, glass, etc., which form optical devices, are divided into individual chips. When dividing this type of optical device wafer into individual chips, a method is known in which the optical device wafer is divided by irradiating the optical device wafer with a laser beam to form a division starting point inside the optical device wafer, and then expanding an expand sheet attached to the optical device wafer (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-248555 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the method described in Patent Document 1, when the wafer has a certain thickness (e.g., 1 mm), it is necessary to widen the incidence area of ​​the laser beam within the surface of the optical device wafer in order to focus the laser beam inside the optical device wafer, which reduces the number of chips that can be obtained from one optical device wafer.

[0005] In addition to the method described in Patent Document 1, there is a method of cutting an optical device wafer with a rotating cutting blade to divide it, but cutting an optical device wafer having a predetermined thickness in multiple steps increases the processing time. In addition, in the case of hard materials such as sapphire, the cutting blade wears rapidly and the cost of consumables is high, making this method uneconomical.

[0006] Therefore, a division method to solve the above problems has been required.

[0007] An object of the present invention is to provide a dividing method that can divide smoothly while suppressing processing time and costs. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, the dividing method of the present invention is a method for dividing a plate-shaped workpiece having devices formed in each area partitioned by a plurality of intersecting division lines, and is characterized by comprising: a first cutting step in which a rotating cutting blade is caused to cut from the front surface of the workpiece along the division lines to form a first cutting groove that does not reach the rear surface of the workpiece; a second cutting step after the first cutting step in which a rotating cutting blade is caused to cut from the rear surface of the workpiece along the first cutting groove to form a second cutting groove that does not reach the bottom of the first cutting groove; and a dividing step after the second cutting step in which an external force is applied to the workpiece to divide the workpiece along the division lines.

[0009] In the above dividing method, the distance between the bottom of the first cut groove and the bottom of the second cut groove may be equal to or less than one tenth of the thickness of the workpiece.

[0010] In the above dividing method, the workpiece may include a sapphire substrate, a SiC substrate, or a glass substrate. Effect of the Invention

[0011] The present invention has an effect of enabling smooth division while suppressing processing time and costs. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view showing an example of a workpiece to be processed by the dividing method according to the first embodiment. [Diagram 2]FIG. 2 is a flowchart showing the flow of the division method according to the first embodiment. [Diagram 3] FIG. 3 is a perspective view that typically shows a state in which a dicing tape is attached to the back surface of the workpiece in the first cutting step of the dividing method shown in FIG. [Figure 4] FIG. 4 is a perspective view that typically shows a state in which a dicing tape is attached to the back surface of the workpiece in the first cutting step of the dividing method shown in FIG. [Diagram 5] FIG. 5 is a perspective view that typically shows a state in which a first cut groove is formed in the surface of the workpiece in the first cutting step of the dividing method shown in FIG. [Figure 6] FIG. 6 is a perspective view that typically shows a state in which a second cut groove is formed on the rear surface of the workpiece in the second cutting step of the dividing method shown in FIG. [Figure 7] FIG. 7 is a side view, partially in section, typically showing a state in which the workpiece is held by the dividing device in the dividing step of the dividing method shown in FIG. [Figure 8] FIG. 8 is a side view, partially in section, that typically shows a state in which the workpiece has been divided into individual device chips in the dividing step of the dividing method shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The form (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiment. Furthermore, the components described below include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the configurations described below can be appropriately combined. Furthermore, various omissions, substitutions, or modifications of the configurations can be made without departing from the gist of the present invention.

[0014] [Embodiment 1] A dividing method according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing an example of a workpiece to be processed by the dividing method according to the first embodiment. Fig. 2 is a flowchart showing the flow of the dividing method according to the first embodiment.

[0015] (Workpiece) The dividing method according to the first embodiment is a method for dividing a workpiece 1 shown in Fig. 1 into individual device chips 10. The workpiece 1 to be processed by the dividing method according to the first embodiment is, for example, a wafer such as a disk-shaped optical device wafer having a substrate 2 made of sapphire, SiC, or glass. That is, in the first embodiment, the workpiece 1 includes a sapphire substrate, a SiC substrate, or a glass substrate as the substrate 2. In the first embodiment, the substrate 2 of the workpiece 1 is made of sapphire, SiC, or glass, and is therefore harder than, for example, silicon constituting the substrate of a semiconductor wafer, i.e., a silicon substrate.

[0016] 1, a workpiece 1 has a plurality of mutually intersecting division lines 4 set on a surface 3 of a substrate 2, and devices 5 formed in each of the areas partitioned by the division lines 4 on the surface 3 of the substrate 2. In the first embodiment, the devices 5 are optical elements such as LEDs (Light-Emitting Diodes), for example.

[0017] The workpiece 1 is divided into individual device chips 10 along the planned division lines 4. The device chips 10 include a part of the substrate 2 and a device 5 formed on the surface 3 of the substrate 2. The workpiece 1 has a thickness 6 of 750 μm or more and 1 mm, which is thicker than a semiconductor wafer in which the substrate 2 is made of silicon or the like. In the first embodiment, the thickness 6 of the workpiece 1 is 750 μm.

[0018] (Dividing method) The dividing method according to the first embodiment is a method for dividing the workpiece 1 along the intended dividing lines 4 into individual device chips 10. Each device chip 10 includes a part of the substrate 2 and a device 5 formed on the surface of the substrate 2. As shown in FIG. 2, the dividing method according to the first embodiment includes a first cutting step 101, a second cutting step 102, and a dividing step 103.

[0019] (First cutting step) Fig. 3 is a perspective view showing a state where a dicing tape is attached to the back surface of a workpiece in the first cutting step of the dividing method shown in Fig. 2. Fig. 4 is a perspective view showing a state where a dicing tape is attached to the back surface of a workpiece in the first cutting step of the dividing method shown in Fig. 2. Fig. 5 is a perspective view showing a state where a first cut groove is formed on the surface of a workpiece in the first cutting step of the dividing method shown in Fig. 2.

[0020] The first cutting step 101 is a step in which a rotating cutting blade 35 is caused to cut from the front surface 3 of the workpiece 1 along the intended division line 4 to form a first cut groove 21 that does not reach the back surface 7 behind the front surface 3 of the workpiece 1. In the first cutting step 101, as shown in Fig. 3, an annular frame 11 having an inner diameter larger than the outer diameter of the workpiece 1 is attached to the outer edge of the back surface 7 behind the front surface 3 of the workpiece 1, and a disk-shaped dicing tape 12 having an outer diameter larger than the outer diameter of the workpiece 1 is opposed to the back surface 7 behind the front surface 3 of the workpiece 1.

[0021] In the first embodiment, in the first cutting step 101, as shown in FIG. 4, the back surface 7 of the workpiece 1 is attached to the center of the dicing tape 12, and the workpiece 1 is supported in the inner opening of the annular frame 11 via the dicing tape 12. In the first embodiment, the dicing tape 12 is an adhesive tape that includes a base layer made of a resin having non-adhesive properties and flexibility, and a glue layer made of a resin having adhesive properties and flexibility that is laminated on the base layer, and the glue layer is attached to the back surface 7 of the workpiece 1. In the present invention, the dicing tape 12 may be a sheet that does not have a glue layer and is composed only of a base material made of a thermoplastic resin, and is attached to the back surface 7 of the workpiece 1 and the annular frame 11 by heating.

[0022] In the first cutting step 101 in the first embodiment, the cutting device 30 shown in Fig. 5 suction-holds the back surface 7 side of the substrate 2 of the workpiece 1 to the holding surface 32 of the chuck table 31 via the dicing tape 12, and clamps the annular frame 11 with the clamping portion 33 around the chuck table 31. In the first cutting step 101 in the first embodiment, the cutting device 30, as shown in Fig. 5, relatively moves the chuck table 31 and the cutting blade 35 rotated about its axis by the spindle 34 of the cutting unit 36 ​​along the planned division line 4, while cutting the cutting blade 35 from the front surface 3 of the workpiece 1 to a depth not reaching the back surface 7, to form a first cut groove 21 in the front surface 3 of the workpiece 1 along the planned division line 4 that does not reach the back surface 7 (i.e., the bottom portion 22 is located at the center in the thickness direction of the workpiece 1). In the first embodiment, in the first cutting step 101 , the cutting device 30 forms first cut grooves 21 in the surface 3 of the workpiece 1 along all of the intended division lines 4 .

[0023] (Second cutting step) Fig. 6 is a perspective view that shows a schematic state of forming a second cut groove on the back surface of the workpiece in the second cutting step of the dividing method shown in Fig. 2. The second cutting step 102 is a step that follows the first cutting step 101, in which a rotating cutting blade 35 is caused to cut along the first cut groove 21 from the back surface 7 of the workpiece 1 to form a second cut groove 23 that does not reach the bottom 22 of the first cut groove 21.

[0024] In the first embodiment, in the second cutting step 102, the dicing tape 12 is peeled off from the rear surface 7 of the workpiece 1. In the first embodiment, in the second cutting step 102, an annular frame 13 (separate from the annular frame 11) whose inner diameter is larger than the outer diameter of the workpiece 1 is attached to the outer edge portion of the front surface 3 of the workpiece 1, and a central portion of a disk-shaped dicing tape 14 (separate from the dicing tape 12) whose outer diameter is larger than the outer diameter of the workpiece 1 is attached to the front surface 3 of the workpiece 1, and the workpiece 1 is supported within an opening on the inside of the annular frame 13 via the dicing tape 14.

[0025] In the first embodiment, the dicing tape 14 is an adhesive tape that, like the dicing tape 12, includes a base layer made of a non-adhesive and flexible resin and a glue layer made of an adhesive and flexible resin laminated on the base layer, and the glue layer is attached to the surface 3 of the workpiece 1. In the present invention, the dicing tape 14 may be a sheet that does not include a glue layer and is made of only a base material made of a thermoplastic resin, and is attached to the surface 3 of the workpiece 1 and the annular frame 13 by heating.

[0026] In the first embodiment, in the second cutting step 102, the cutting device 30 shown in Fig. 6 suction-holds the front surface 3 side of the substrate 2 of the workpiece 1 to the holding surface 32 of the chuck table 31 via the dicing tape 14, and clamps the annular frame 13 with the clamping portion 33. In the first embodiment, in the second cutting step 102, as shown in Fig. 6, the cutting device 30 relatively moves the chuck table 31 and the cutting blade 35 rotated about its axis by the spindle 34 of the cutting unit 36 ​​along the intended division line 4, while cutting the cutting blade 35 from the rear surface 7 of the workpiece 1 to a depth not reaching the bottom 22 of the first cut groove 21, to form a second cut groove 23 along the rear surface 7 of the workpiece 1 that does not reach the bottom 22 of the first cut groove 21 (i.e., the bottom 24 is located at the center in the thickness direction of the workpiece 1). In the first embodiment, in the second cutting step 102 , the cutting device 30 forms second cut grooves 23 in the rear surface 7 of the workpiece 1 along the first cut grooves 21 formed on all of the intended division lines 4 .

[0027] In addition, in the first embodiment, the distance 25 between the bottom 22 of the first cut groove 21 and the bottom 24 of the second cut groove 23 formed in the cutting steps 101 and 102 is 1 / 10 or less of the thickness 6 of the workpiece 1. In addition, in the first embodiment, the distance 25 between the bottom 22 of the first cut groove 21 and the bottom 24 of the second cut groove 23 formed in the cutting steps 101 and 102 is desirably 30 / 750 or more of the thickness 6 of the workpiece 1.

[0028] (split step) Fig. 7 is a schematic side view, partially in section, showing a state in which a workpiece is held in a dividing device in the dividing step of the dividing method shown in Fig. 2. Fig. 8 is a schematic side view, partially in section, showing a state in which the workpiece has been divided into individual device chips in the dividing step of the dividing method shown in Fig. 2.

[0029] The dividing step 103 is a step of dividing the workpiece 1 along the dividing lines 4 by applying an external force to the workpiece 1 after the second cutting step 102. In the dividing step 103 in the first embodiment, as shown in FIG. 7, the dividing device 50 places the surface 3 side of the workpiece 1 on the holding surface 52 of the holding table 51 via the dicing tape 14, and the annular frame 13 is placed on the upper surface 54 of the mounting plate 53 provided on the outer periphery of the holding table 51 via the outer edge of the dicing tape 14. At this time, the holding surface 52 of the holding table 51 and the upper surface 54 of the mounting plate 53 are located on the same plane. In the first embodiment, in the dividing step 103, the dividing device 50 clamps the annular frame 13 between the clamp portion 55 and the upper surface 54 of the mounting plate 53.

[0030] In the first embodiment, in the dividing step 103, the dividing device 50 relatively moves the holding table 51 and the mounting plate 53 in a direction perpendicular to the holding surface 52, i.e., the front surface 3 of the workpiece 1 placed on the holding table 51. In the first embodiment, in the dividing step, as shown in Fig. 8, the dividing device 50 raises the holding table 51 and expands the dicing tape 14 in the planar direction.

[0031] Then, as a result of the expansion of the dicing tape 14, a radial tensile force acts on the dicing tape 14, and the workpiece 1 is subjected to a radial tensile force, which is an external force, from the dicing tape 14. In the first embodiment, in the dividing step 103, the workpiece 1 has cut grooves 21, 23 formed along the intended division lines 4, so that when a radial tensile force is applied as an external force, the workpiece 1 is divided into individual device chips 10 starting from the cut grooves 21, 23, as shown in Fig. 8, and the intervals between the device chips 10 are widened. The device chips 10 are then picked up from the dicing tape 14.

[0032] The dividing method according to the first embodiment described above forms a first cut groove 21 on the front surface 3 side in a first cutting step 101, and forms a second cut groove 23 on the back surface 7 side in a second cutting step 102, the second cut groove 23 not reaching the bottom 22 of the first cut groove 21. For this reason, the dividing method according to the first embodiment can reduce the amount of cutting of the workpiece 1, and can reduce the number of cuts of the workpiece 1 and the amount of wear of the cutting blade 35.

[0033] Moreover, in the dividing method according to the first embodiment, after the cutting steps 101 and 102, an external force is applied to the workpiece 1 to divide it into individual device chips 10.

[0034] As a result, the dividing method according to the first embodiment has the effect of enabling smooth division while suppressing processing time and costs, even if the workpiece 1 is harder than a sapphire substrate, a SiC substrate, or a silicon substrate including a glass substrate as the substrate 2, and is thicker than a semiconductor wafer having a thickness 6 of 750 μm or more.

[0035] Furthermore, in the dividing method according to the first embodiment, the cut grooves 21 and 23 are formed as the dividing start points in the dividing step 103, so that no laser beam is irradiated when the dividing start points are formed.

[0036] As a result, the division method according to embodiment 1 can suppress an increase in the width of the planned division lines 4 even in a workpiece 1 that is thicker than a semiconductor wafer having a thickness of 750 μm or more, and can suppress a decrease in the number of device chips 10 that can be obtained from the workpiece 1.

[0037] In order to suppress the amount of cutting by the cutting blade 35, it is desirable to increase the distance 25 between the bottoms 22, 24 of the cutting grooves 21, 23 described above. However, if the distance 25 is made too long, an undivided division line 4 will be generated after the division step 103. Therefore, the inventors of the present invention confirmed the effect of the division method according to the first embodiment. The results are shown in Table 1 below.

[0038] In the confirmation, the division states of the comparative example, the present invention 1, the present invention 2, and the present invention 3, which have different distances 25 between the bottoms 22, 24 of the cut grooves 21, 23, and in which the workpiece 1 has a substrate 2 made of sapphire and a thickness 6 of 750 μm, were confirmed after being divided in the dividing step 103. In Table 1, the division states of the workpieces in which all of the division lines 4 were divided are indicated by a circle, and the division states of the workpieces in which at least some of the division lines 4 were not divided are indicated by an X.

[0039] [Table 1]

[0040] In the comparative example, the distance 25 was set to 90 μm. In the present invention 1, the distance 25 was set to 30 μm. In the present invention 2, the distance 25 was set to 50 μm. In the present invention 3, the distance 25 was set to 75 μm.

[0041] According to Table 1, in the comparative example, some of the dividing lines 4 did not divide. In contrast to such a comparative example, in present invention products 1, 2, and 3, all of the dividing lines 4 divided.

[0042] Therefore, according to Table 1, by setting the distance 25 between the bottoms 22, 24 of the cutting grooves 21, 23 formed in the cutting steps 101, 102 to be 30 / 750 or more and 1 / 10 or less of the thickness 6 of the workpiece 1, it has become clear that even if the substrate 2 is harder than a sapphire substrate, a SiC substrate, or a silicon substrate including a glass substrate and the workpiece 1 is thicker than a semiconductor wafer having a thickness 6 of 750 μm or more, the amount of cutting of the workpiece 1 can be reduced, and the workpiece 1 can be divided into individual device chips 10 while reducing the number of cuts of the workpiece 1 and the amount of wear of the cutting blade 35.

[0043] In short, according to Table 1, by setting the distance 25 between the bottoms 22, 24 of the cutting grooves 21, 23 to be 30 / 750 or more and 1 / 10 or less of the thickness 6 of the workpiece 1, it has become clear that even if the substrate 2 is harder than a sapphire substrate, a SiC substrate, or a silicon substrate including a glass substrate and the workpiece 1 is thicker than a semiconductor wafer having a thickness 6 of 750 μm or more, it can be smoothly divided while suppressing processing time and costs.

[0044] It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. [Explanation of symbols]

[0045] 1 Workpiece 3 surface 4. Planned division line 5 Devices 6 Thickness 7 Back side 21 First cutting groove 22 Bottom 23 Second cutting groove 24 Bottom 35 Cutting Blade 101 First cutting step 102 Second cutting step 103 division steps

Claims

1. A method for dividing a plate-shaped workpiece having devices formed in each of areas partitioned by a plurality of intersecting division lines, comprising the steps of: a first cutting step of cutting a first cutting groove that does not reach a back surface of the workpiece by cutting the workpiece from a front surface of the workpiece along the intended division line with a rotating cutting blade; a second cutting step in which a rotating cutting blade is caused to cut along the first cut groove from the back surface of the workpiece after the first cutting step, to form a second cut groove that does not reach the bottom of the first cut groove; a dividing step of dividing the workpiece along the dividing lines by applying an external force to the workpiece after the second cutting step; A division method comprising:

2. 2. The method according to claim 1, wherein the distance between the bottom of the first cut groove and the bottom of the second cut groove is equal to or less than one tenth of the thickness of the workpiece.

3. 3. The method according to claim 1, wherein the workpiece includes a sapphire substrate, a SiC substrate, or a glass substrate.

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