Method for dividing a single crystal substrate and method for manufacturing a device chip

Abstract

To suppress deterioration in yield by improving a processing quality of a single crystal substrate.SOLUTION: A division method of a single crystal substrate that performs cleavage to divide the single crystal substrate, comprises: a holding step of holding a single crystal substrate in which a plurality of division schedules lines along a first direction are set on one surface so as to be along a predetermined crystal direction which can perform the cleavage of the single crystal substrate, by a chuck table of a laser processing device; a laser beam irradiation step of intermittently forming an acceleration region for accelerating the cleavage of the single crystal substrate along each division schedule line by irradiation with a laser beam along each division schedule line from a laser beam irradiation unit of the laser processing device after the holding step; and a division step of dividing the single crystal substrate by performing the cleavage of the single crystal substrate along each division schedule line by applying an external force to the single crystal substrate after the laser beam irradiation step.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for splitting a single crystal substrate and a method for manufacturing device chips by splitting a single crystal substrate to manufacture a plurality of device chips.

Background Art

[0002] When manufacturing light-emitting device chips such as LEDs (Light Emitting Diodes) and LDs (Laser Diodes), for example, a workpiece having a single crystal substrate (i.e., a wafer) is used. After forming light-emitting elements in each region partitioned by a plurality of planned division lines set in a grid pattern on the wafer, the wafer is divided along each planned division line.

[0003] As the material of the single crystal substrate, for example, sapphire, silicon carbide, and gallium nitride are used. When dividing the wafer, for example, a scriber having a blade portion formed of a high-hardness material such as diamond (i.e., a diamond scriber) is used.

[0004] A method is known in which a scribe groove is formed along each planned division line using this scriber, and then the wafer is divided by applying an external force to the scribe groove (see, for example, Patent Document 1).

[0005] When splitting a single crystal substrate, a method has been proposed in which a predetermined crystal orientation and a planned division line are set substantially parallel, a scribe groove is formed along the planned division line, and then the single crystal substrate is split along each planned division line to divide the wafer (see, for example, Patent Document 2). However, when the scribe groove is formed relatively shallow, there is a problem that an undivided region occurs even when an external force is applied to the single crystal substrate, and the single crystal substrate is not completely divided.

[0006] On the other hand, when scribe grooves are formed relatively deep, applying external force to the single-crystal substrate makes it less likely for undivided regions to occur. However, when scribe grooves are formed relatively deep, if the longitudinal direction of the scribe grooves deviates from the predetermined crystal orientation used for cleavage, cracks may occur in a direction that intersects the longitudinal direction of the planned division line at an angle. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2015-207579 [Patent Document 2] Japanese Patent Publication No. 2012-119479 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] When cracks of this type occur in an oblique direction, causing them to extend beyond the planned division line, it results in manufacturing defects for the light-emitting device chip, leading to a decrease in yield. This invention has been made in view of these problems, and aims to suppress the decrease in yield by improving the processing quality of single-crystal substrates. [Means for solving the problem]

[0009] According to one aspect of the present invention, a method for dividing a single crystal substrate by cleaving it is provided, comprising: a holding step of holding the single crystal substrate, which is set on one surface such that a plurality of division lines along a first direction are aligned with a predetermined crystal orientation that allows the single crystal substrate to be cleaved, in a chuck table of a laser processing apparatus; a laser beam irradiation step of intermittently forming promotion regions along each division line to promote cleavage of the single crystal substrate by irradiating a laser beam from a laser beam irradiation unit of the laser processing apparatus along each division line after the holding step; and a dividing step of dividing the single crystal substrate by applying an external force to the single crystal substrate and cleaving it along each division line after the laser beam irradiation step.

[0010] Preferably, in the holding step, the other side of the single crystal substrate opposite to the one side is held by the chuck table, and in the laser beam irradiation step, a laser beam having a wavelength absorbed by the single crystal substrate is irradiated to intermittently form processing grooves having a depth that does not completely cut the single crystal substrate along each planned division line as the facilitating region.

[0011] Preferably, in the laser beam irradiation step, a first processing groove having a first depth from that surface is formed as the acceleration region at one end of each planned division line in the first direction, and a second processing groove having a second depth shallower than the first depth is intermittently formed as the acceleration region in the region other than the one end of each planned division line, and in the division step, the single crystal substrate is divided by sequentially pressing the pressing blade from one end toward the other end located on the opposite side of the one end.

[0012] Preferably, in the laser beam irradiation step, a laser beam having a wavelength that penetrates the single crystal substrate is irradiated to intermittently form weakened regions, which are the enhancement regions, along each planned division line, by reducing the strength of the single crystal substrate.

[0013] Preferably, in the laser beam irradiation step, a first vulnerable region having a first depth from that surface is formed as the accelerating region at one end of each planned division line in the first direction, and a second vulnerable region having a second depth shallower than the first depth is intermittently formed as the accelerating region in the region other than the one end of each planned division line, and in the division step, the single crystal substrate is divided by sequentially pressing the pressing blade from one end toward the other end located on the opposite side of the one end.

[0014] Preferably, a plurality of division lines are further set on one surface of the single crystal substrate along a second direction perpendicular to the first direction, and in the laser beam irradiation step, when the enhancement region is formed intermittently along each division line in the first direction, the enhancement region is formed in each of the plurality of intersection regions where the plurality of division lines along the first direction and the plurality of division lines along the second direction intersect.

[0015] Preferably, a plurality of division lines are further set on one surface of the single crystal substrate along a second direction perpendicular to the first direction, and in the laser beam irradiation step, when the enhancement region is intermittently formed along each division line in the first direction, the enhancement region is formed in the region excluding the plurality of intersection regions where the plurality of division lines along the first direction and the plurality of division lines along the second direction intersect.

[0016] According to another aspect of the present invention, a method for manufacturing a device chip by dividing a single crystal substrate, comprising: a holding step of holding a single crystal substrate with a chuck table of a laser processing apparatus, wherein a plurality of division lines arranged in a grid along a first direction and a second direction intersecting each other are set on one surface such that a plurality of division lines along the first direction are aligned with a predetermined crystal orientation that can cleave the single crystal substrate; a first laser beam irradiation step, after the holding step, irradiating a laser beam from a laser beam irradiation unit of the laser processing apparatus along each of the division lines in the first direction to intermittently form an acceleration region along each of the division lines in the first direction to promote cleavage of the single crystal substrate; and after the holding step, the laser beam irradiation unit A method for manufacturing a device chip is provided, comprising: a second laser beam irradiation step of irradiating the single crystal substrate with a laser beam along a plurality of planned division lines in a second direction to form division starting points along each of the planned division lines in the second direction; a first division step of applying an external force to the promotion region of the single crystal substrate after the first and second laser beam irradiation steps to cleave the single crystal substrate along each of the planned division lines in the first direction; and a second division step of applying an external force to the division starting points of the single crystal substrate after the first and second laser beam irradiation steps to divide the single crystal substrate, wherein the single crystal substrate is divided into a plurality of device chips after the first and second division steps.

[0017] According to yet another aspect of the present invention, a method for dividing a single crystal substrate by cleaving it is provided, comprising: a holding step of holding the single crystal substrate, which has a plurality of division lines along a first direction set on one surface such that the single crystal substrate is aligned with a predetermined crystal orientation that allows for cleavage, in a chuck table of a laser processing apparatus; a laser beam irradiation step, after the holding step, of irradiating a laser beam from a laser beam irradiation unit of the laser processing apparatus along each division line to promote the cleavage of the single crystal substrate, in a range from the surface to a predetermined depth at one end of the division line in the first direction; and a dividing step, after the laser beam irradiation step, of applying an external force to the single crystal substrate by sequentially pressing a pressing blade from one end toward the other end located opposite to the one end, thereby dividing the single crystal substrate by cleaving it along the division lines.

[0018] Preferably, the predetermined depth is 15% to 80% of the thickness of the single crystal substrate from one surface to the other surface located opposite to that surface, and in the laser beam irradiation step, the enhancement region is formed at one end in the range from the one surface to the predetermined depth. [Effects of the Invention]

[0019] In the method for dividing a single crystal substrate and manufacturing a device chip according to the present invention, a laser beam is irradiated from the laser beam irradiation unit of a laser processing apparatus to intermittently form promotion regions for promoting cleavage of the single crystal substrate along each planned division line in the first direction (laser beam irradiation step, first laser beam irradiation step).

[0020] In this way, since a laser processing device is used to form an acceleration region to promote cleavage in the single-crystal substrate, the depth position of the acceleration region in the single-crystal substrate becomes easier to control compared to when a diamond scriber is used to form scribe grooves. Therefore, it is possible to suppress the occurrence of undivided regions when dividing the single-crystal substrate.

[0021] After the laser beam irradiation step, an external force is applied to the single crystal substrate, and the single crystal substrate is divided by splitting the single crystal substrate along each planned division line in the first direction (division step, first division step).

[0022] The acceleration regions intermittently formed along the planned division line in the laser beam irradiation step function as guides when the single crystal substrate splits in the division step. Therefore, even when the longitudinal direction of the acceleration region is formed deviating from a predetermined crystal orientation, the occurrence of cracks in an oblique direction that protrude beyond the planned division line can be suppressed. Accordingly, a decrease in the yield during the manufacture of the light-emitting device chips can be suppressed.

[0023] Further, in the method for dividing a single crystal substrate according to another aspect of the present invention, by irradiating a laser beam from the laser beam irradiation unit of the laser processing apparatus, an acceleration region for promoting the splitting of the single crystal substrate is formed in a range from one surface to a predetermined depth at one end portion in the first direction of the planned division line (laser beam irradiation step).

[0024] Thereby, compared with the case of forming a scribe groove using a diamond scriber, the depth position of the acceleration region in the single crystal substrate becomes easier to control, so that the occurrence of an undivided region when dividing the single crystal substrate can be suppressed.

[0025] After the laser beam irradiation step, by sequentially pressing the pressing blade from one end portion toward the other end portion located on the opposite side of the one end portion, an external force is applied to the single crystal substrate, and the single crystal substrate is divided by splitting the single crystal substrate along the planned division line in the first direction (division step).

[0026] The cleavage region formed at one end during the laser beam irradiation step initiates cleavage, and by sequentially pressing the pressing blade from one end to the other, the single crystal substrate can be sequentially cleaved at the pressing positions of the pressing blade. Therefore, compared to the case where the pressing blade is pressed almost simultaneously across the range from one end to the other, the occurrence of cracks in the oblique direction can be suppressed, thus suppressing a decrease in yield during the manufacturing of light-emitting device chips. [Brief explanation of the drawing]

[0027] [Figure 1] This is a flowchart of the division method. [Figure 2] Figure 2(A) is a perspective view of the workpiece, and Figure 2(B) is a cross-sectional view of the workpiece. [Figure 3] This is a diagram showing the holding step. [Figure 4] This figure shows the laser beam irradiation step. [Figure 5] This is a cross-sectional view of the workpiece after the laser beam irradiation step. [Figure 6] This figure shows the second laser beam irradiation step. [Figure 7] This is a partial cross-sectional side view showing the division steps. [Figure 8] This is a partial cross-sectional side view showing the division steps. [Figure 9] Figure 9(A) shows a continuous scribe groove, Figure 9(B) shows how a crack occurs in an oblique direction, Figure 9(C) shows an intermittent machining groove, and Figure 9(D) shows how the intermittent machining groove acts as a guide to split the single crystal substrate. [Figure 10] Figure 10(A) is a partial cross-sectional side view showing the second division step, and Figure 10(B) is a partial cross-sectional side view showing the second division step. [Figure 11] This is a perspective view of a light-emitting device chip. [Figure 12] This is a cross-sectional view of the workpiece after the laser beam irradiation step in the second embodiment. [Figure 13]Figure 13(A) shows the pressing blade being applied to one end, and Figure 13(B) shows the pressing blade being applied to the other end. [Figure 14] Figure 14(A) shows the situation when the pressing blade is pressed against one end, and Figure 14(B) shows the situation when the pressing blade is pressed against the other end. [Figure 15] This is a cross-sectional view of the workpiece after the laser beam irradiation step of the third embodiment. [Figure 16] This is a cross-sectional view of the workpiece after the laser beam irradiation step of the fourth embodiment. [Figure 17] This figure shows the laser beam irradiation step of the fifth embodiment. [Figure 18] Figure 18(A) is a cross-sectional view of the workpiece after the laser beam irradiation step in the sixth embodiment, and Figure 18(B) is a cross-sectional view of the workpiece after the laser beam irradiation step in the seventh embodiment. [Modes for carrying out the invention]

[0028] An embodiment of one aspect of the present invention will be described with reference to the attached drawings. Figure 1 is a flowchart of a method for dividing a single crystal substrate 13 (see Figure 2(A), etc.) of a workpiece 11 according to the first embodiment, and a method for manufacturing a plurality of light-emitting device chips (device chips) 33 (see Figure 11) produced by said division.

[0029] First, let's describe the workpiece 11 that will be divided. Figure 2(A) is a perspective view of the workpiece 11, and Figure 2(B) is a cross-sectional view of the workpiece 11 along A-A in Figure 2(A). The workpiece 11 is a wafer having a disc-shaped single crystal substrate 13.

[0030] The single-crystal substrate 13 is used as a substrate for forming the light-emitting element 15. In this embodiment, the single-crystal substrate 13 is made of gallium arsenide (GaAs), but the single-crystal substrate 13 may be made of other compound semiconductor materials having a cleavable crystal orientation (for example, indium phosphide (InP), gallium nitride (GaN)).

[0031] The single crystal substrate 13 includes a first crystal orientation [0-11] and a second crystal orientation

[0011] which are orthogonal to each other. The first crystal orientation [0-11] is parallel to the first direction 11a shown in Figure 2(A), and the second crystal orientation

[0011] is parallel to the second direction 11b shown in Figure 2(A). The first direction 11a and the second direction 11b are also orthogonal to each other.

[0032] In the first crystal orientation [0-11], cracks are more likely to occur compared to the second crystal orientation

[0011] , so the single crystal substrate 13 is more easily cleaved. In the second crystal orientation

[0011] , cracks are less likely to occur compared to the first crystal orientation [0-11], but cleavage of the single crystal substrate 13 along the second crystal orientation is also possible.

[0033] In other words, both the first crystal orientation [0-11] and the second crystal orientation

[0011] are crystal orientations that can cleave the single crystal substrate 13, but the first crystal orientation [0-11] is relatively easier to cleave.

[0034] Furthermore, even when the single-crystal substrate 13 is formed of another compound semiconductor material, a first crystal orientation that is relatively easy to cleave and a second crystal orientation that is less easy to cleave than the first crystal orientation can be appropriately selected.

[0035] The single crystal substrate 13 is thinned to a predetermined thickness 13c by grinding or the like. The single crystal substrate 13 in this embodiment has a thickness 13c of 90 μm. The thickness 13c is the length from the surface 13a to the back surface (other surface) 13b located on the opposite side of the surface 13a.

[0036] On the surface (one side) 13a of the single crystal substrate 13, a plurality of first division lines 17a along the first direction 11a of the single crystal substrate 13 and a plurality of second division lines 17b along the second direction 11b of the single crystal substrate 13 are set in a grid pattern.

[0037] In Figure 2(A), the first planned division line 17a is shown parallel to the first direction 11a, but as will be explained later, the first planned division line 17a may be slightly offset from the first direction 11a (see, for example, Figure 9(A)).

[0038] In other words, when the first planned division line 17a is said to be aligned with the first direction 11a, it includes cases where the first planned division line 17a is perfectly parallel to the first direction 11a, as well as cases where it is slightly offset (for example, by about 1 to 2 degrees). The same applies when the second planned division line 17b is aligned with the second direction 11b.

[0039] The first planned division line 17a and the second planned division line 17b are perpendicular (intersect). In this embodiment, the width (length in the direction perpendicular to the longitudinal direction) of each of the first planned division line 17a and each of the second planned division line 17b is 20 μm, but the width of the planned division line (i.e., the street) is not limited to this value.

[0040] Each of the rectangular regions defined by multiple first division lines 17a and multiple second division lines 17b has a light-emitting element 15 such as an LED or LD formed within it. The number of light-emitting elements 15 is not limited to the example shown in Figure 2(A), etc.

[0041] After thinning the workpiece 11, and before laser processing the workpiece 11, a workpiece unit 23 is formed, in which the workpiece 11 is supported by a metal annular frame 21 via a resin protective tape 19, as shown in Figure 3.

[0042] Specifically, the workpiece unit 23 is formed by attaching the central part of the circular protective tape 19 to the back surface 13b of the single crystal substrate 13, and the outer edge of the protective tape 19 to one surface of the annular frame 21.

[0043] Next, the single-crystal substrate 13 of the workpiece unit 23 is laser-processed using the laser processing device 2 (see Figure 3). The laser processing device 2 will now be described with reference to Figures 3 and 4. The laser processing device 2 has a disc-shaped chuck table 4.

[0044] The chuck table 4 has a disc-shaped frame made of metal. A disc-shaped recess is formed in the center of the frame, and a disc-shaped porous plate (not shown) made of ceramics is fixed in this recess.

[0045] A suction source (not shown), such as a vacuum pump, is connected to the frame. When negative pressure from the suction source is transmitted to the porous plate via the frame, negative pressure is generated on the upper surface of the porous plate. The upper surface of the frame and the upper surface of the porous plate are substantially flush, and function as a substantially flat holding surface for suction and holding the workpiece 11.

[0046] The holding surfaces are positioned approximately parallel to the X-Y plane, which is composed of the X-axis direction (machining feed direction) and the Y-axis direction (indexing feed direction). The X-axis, Y-axis, and Z-axis directions (vertical direction, up and down direction) are mutually orthogonal.

[0047] Multiple clamping units (not shown) are provided on the outer circumference of the chuck table 4 at approximately equal intervals along the circumferential direction of the chuck table 4. Each clamping unit grips the annular frame 21 of the workpiece unit 23.

[0048] The chuck table 4 is supported by a table rotation mechanism (not shown) that includes a rotational drive source (not shown), such as a motor. When the rotational drive source is operated, the chuck table 4 can rotate around a predetermined axis of rotation along the Z-axis direction.

[0049] The table rotation mechanism is supported by a horizontal movement mechanism (not shown). The horizontal movement mechanism includes a ball screw type X-axis movement mechanism and a Y-axis movement mechanism (both not shown).

[0050] The horizontal movement mechanism can move the table rotation mechanism and the chuck table 4 along the X-axis and Y-axis directions. In other words, the horizontal movement mechanism can perform machining feed and indexing feed of the chuck table 4.

[0051] The horizontal movement mechanism is fixed to the base (not shown) of the laser processing device 2. A column (not shown) is provided at one end of the base in the Y-axis direction, with its longitudinal portion aligned along the Z-axis direction and its upper end positioned above the horizontal movement mechanism.

[0052] The column section is equipped with a ball screw type Z-axis movement mechanism (not shown). The Z-axis movement mechanism includes a movable plate (not shown) that can move along the Z-axis direction, and a laser beam irradiation unit 6 is fixed to this movable plate (see Figure 4).

[0053] The laser beam irradiation unit 6 has a laser oscillator (not shown). The laser oscillator contains, for example, an Nd:YVO4 crystal as the laser medium. A pulsed laser beam with a wavelength of 1064 nm is emitted from the laser oscillator by Q-switched pulse oscillation.

[0054] The laser beam is irradiated onto the workpiece 11 after its wavelength is converted as needed. For example, the wavelength of the pulsed laser beam emitted from the laser oscillator is converted to a wavelength of 355 nm (the wavelength absorbed by the single-crystal substrate 13) via a nonlinear optical crystal provided in the laser beam irradiation unit 6, and then irradiated onto the workpiece 11.

[0055] The wavelength-converted laser beam is incident on an acousto-optic modulator (hereinafter abbreviated as AOM, based on the initials of Acousto-Optic Modulator) located in the laser beam irradiation unit 6. The AOM is controlled by an electrical signal.

[0056] The AOM has a switching function that switches between irradiating the workpiece 11 with the laser beam (output ON state) and not irradiating the workpiece 11 with the laser beam (output OFF state) according to the specifications given by the input electrical signal.

[0057] The laser beam irradiation unit 6 has a cylindrical housing 8 whose longitudinal portion is arranged along the Y-axis. An irradiation head 10 is fixed to the tip of the housing 8. The irradiation head 10 houses a focusing lens (not shown) and the like.

[0058] In this embodiment, the irradiation head 10 emits a pulsed laser beam L having a wavelength (for example, 355 nm) that is absorbed by the single-crystal substrate 13 via a nonlinear optical crystal, AOM, etc., and is irradiated along the Z-axis toward the holding surface of the chuck table 4.

[0059] A microscope camera unit 12 is fixed near the irradiation head 10. The microscope camera unit 12 includes an objective lens and an image sensor such as a CCD (Charge-Coupled Device) image sensor.

[0060] Furthermore, the microscope camera unit 12 is equipped with a light source such as an LED used during imaging. The housing 8, illumination head 10, microscope camera unit 12, etc., can be moved integrally along the Z-axis direction by a Z-axis movement mechanism.

[0061] The operation of the chuck table 4, suction source, multiple clamping units, rotational drive source, horizontal movement mechanism, Z-axis movement mechanism, laser beam irradiation unit 6, microscope camera unit 12, etc., is controlled by the control unit (not shown) of the laser processing apparatus 2.

[0062] A control unit is composed of a computer that includes, for example, a processor (processing unit) represented by a CPU (Central Processing Unit), main memory such as DRAM (Dynamic Random Access Memory) and SRAM (Static Random Access Memory), and auxiliary storage such as flash memory and hard disk drives.

[0063] The auxiliary storage device stores software containing a predetermined program. The control unit's functions are realized by operating the processing unit and other components according to this software. Next, the breaking device 14 used when dividing the single crystal substrate 13 after laser processing will be described with reference to Figures 7 and 8.

[0064] The braking device 14 has a support base 16 that supports the laser-processed workpiece 11. The support base 16 has a recess 16b on its upper surface 16a, formed such that its longitudinal portion is aligned in a predetermined direction (in the example shown in Figure 8, the depth direction of the paper) (see Figure 8). The longitudinal portion of the recess 16b is longer than the diameter of the single crystal substrate 13.

[0065] A pressing blade 18 is provided above the support base 16. The pressing blade 18 is positioned along a predetermined direction (the depth direction of the paper in the example shown in Figure 8) such that its straight lower end 18a is at the same height along the longitudinal direction of the pressing blade 18.

[0066] The longitudinal length of the pressing blade 18 is longer than the diameter of the single crystal substrate 13, and a ball screw type first movement mechanism (not shown) for pushing the pressing blade 18 downward is provided at the top of the pressing blade 18. By pushing the pressing blade 18 downward with the first movement mechanism, a downward external force can be applied to the single crystal substrate 13 placed on the support base 16.

[0067] Next, a method for dividing the single crystal substrate 13 by cleaving it, and a method for manufacturing multiple light-emitting device chips 33 by dividing the single crystal substrate 13 will be explained according to the flowchart shown in Figure 1.

[0068] First, the workpiece unit 23 is placed on the chuck table 4, and the back surface 13b of the single crystal substrate 13 is held in place by suction from the holding surface of the chuck table 4 via the protective tape 19 (holding step S10). Figure 3 shows the holding step S10.

[0069] After the holding step S10, the surface 13a is imaged using the microscope camera unit 12 to calculate the deviation between the first division line 17a and the X-axis direction (i.e., alignment is performed). Next, the orientation of the chuck table 4 in the X-Y plane is adjusted so that the first division line 17a is approximately parallel to the X-axis direction.

[0070] Then, with the focusing point of the laser beam L positioned at one end of the first planned division line 17a at a height near the surface 13a, the chuck table 4 is fed at a predetermined speed. The processing conditions in the laser beam irradiation step S20 are, for example, as follows.

[0071] Wavelength: 355nm Average output: 0.5W Repeat frequency: 160kHz Machining feed rate: 10 mm / s Number of passes: 1

[0072] The number of passes refers to the number of times the laser beam L is irradiated onto the single crystal substrate 13 along one first division line 17a (or one second division line 17b) at a predetermined processing feed rate.

[0073] For example, when there are two passes, the focusing point of the laser beam L is moved from one end to the other at a predetermined processing feed rate (1st pass), and then moved from the other end to the first end at a predetermined processing feed rate (2nd pass).

[0074] In the laser beam irradiation step S20 of this embodiment, the irradiation and non-irradiation of the laser beam L along the first planned division line 17a are controlled using the AOM described above, thereby intermittently forming processing grooves (accelerating regions) 25a along the first planned division line 17a to promote cleavage of the single crystal substrate 13.

[0075] Figure 4 shows the laser beam irradiation step (first laser beam irradiation step) S20. In this embodiment, the processing groove 25a is formed intermittently along the first planned division line 17a so as to avoid the side region of the light-emitting element 15.

[0076] Specifically, processing grooves 25a are formed in two end regions 13d located outside the single crystal substrate 13 beyond the intersection region 13e between one first division line 17a and the outermost second division line 17b, and in multiple intersection regions 13e where multiple first division lines 17a and multiple second division lines 17b intersect.

[0077] After forming a machining groove 25a along one of the first division line 17a, the chuck table 4 is indexed and fed to intermittently form machining grooves 25a along other first division line 17a adjacent in the Y-axis direction to the first division line 17a that was machined immediately before.

[0078] In this manner, processing grooves 25a are intermittently formed along all of the first planned division lines 17a. As shown in Figure 5, the processing grooves 25a have a predetermined depth 25a1 that does not completely cut through the single crystal substrate 13. The predetermined depth 25a1 is, for example, 5% or more and less than 15% of the single crystal substrate 13 from the surface 13a.

[0079] In this embodiment, where the thickness 13c of the single crystal substrate 13 is 90 μm, the predetermined depth 25a1 is 10 μm (approximately 11%) from the surface 13a. Figure 5 is a cross-sectional view of the workpiece 11 after the laser beam irradiation step S20.

[0080] After the laser beam irradiation step S20, the surface 13a is imaged using the microscope camera unit 12, and then the orientation of the chuck table 4 is adjusted so that the second division line 17b is approximately parallel to the X-axis direction.

[0081] And the focusing point L of the laser beam L P With the (see Figure 6) positioned at one end of one of the planned second division lines 17b on the single crystal substrate 13, the chuck table 4 is fed at a predetermined speed (second laser beam irradiation step S30).

[0082] Figure 6 shows the second laser beam irradiation step S30. The processing conditions in the second laser beam irradiation step S30 are, for example, as follows.

[0083] Wavelength: 355nm Average output: 1.5W Repeat frequency: 160kHz Machining feed rate: 10 mm / s Number of passes: 1

[0084] In the second laser beam irradiation step S30, the laser beam L is irradiated from the irradiation head 10 along each second division line 17b to form processing grooves (division starting points) 25b along each second division line 17b of the single crystal substrate 13.

[0085] In this embodiment, the machining groove 25b is formed continuously along the second planned division line 17b, but the machining groove 25b may also be formed intermittently along the second planned division line 17b. The machining groove 25b has a predetermined depth 25b1 that does not completely cut the single crystal substrate 13 (see Figure 10(B)).

[0086] The predetermined depth 25b1 is deeper than the predetermined depth 25a1 of the processed groove 25a. The predetermined depth 25b1 is 15% to 80% of the thickness 13c of the single crystal substrate 13, more preferably 20% to 50%.

[0087] As described above, the second direction 11b of the single crystal substrate 13 is less prone to cleavage than the first direction 11a. Therefore, in this embodiment, the processing groove 25b is formed deeper than the processing groove 25a. This suppresses the occurrence of an undivided region in the second division step S50.

[0088] In the second laser beam irradiation step S30, the average output of the laser beam L is increased, but instead of increasing the average output, or in conjunction with it, the processing feed rate may be lowered, or the number of passes may be increased.

[0089] By slowing down the processing feed rate, the amount of energy irradiated per unit time in a unit area increases, thus achieving an effect similar to that of increasing the average output. Similarly, by increasing the number of passes, the amount of time the laser beam L is irradiated in a unit area increases, thus achieving an effect similar to that of increasing the average output.

[0090] In this embodiment, the second laser beam irradiation step S30 is performed after the laser beam irradiation step S20, but the laser beam irradiation step S20 may be performed after the second laser beam irradiation step S30.

[0091] After the laser beam irradiation step S20 and the second laser beam irradiation step S30, the single crystal substrate 13 is divided using the braking device 14 (dividing step (first dividing step) S40).

[0092] Figure 7 is a partial cross-sectional side view showing the division step S40, and Figure 8 is a partial cross-sectional side view showing the division step S40 when viewed from a 90-degree different orientation from that of Figure 7.

[0093] In the division step S40, first, the release paper 19a, which was initially attached to the adhesive layer of the protective tape 19, is placed on the surface 13a side of the single crystal substrate 13. At this time, the release paper 19a is attached to the protective tape 19 using the adhesive layer exposed between the single crystal substrate 13 and the annular frame 21, and is integrated with the workpiece unit 23.

[0094] Next, the position of the single crystal substrate 13 on top is adjusted so that the intermittently formed processing grooves 25a along one of the first planned division lines 17a are located on the recesses 16b. At this time, the single crystal substrate 13 is placed on the support base 16 so that the front surface 13a faces downwards and the back surface 13b faces upwards.

[0095] Subsequently, by pressing the pressing blade 18 into the recess 16b, a downward external force is applied to the single crystal substrate 13 from the back surface 13b side. This allows the single crystal substrate 13 to be cleaved along one of the first planned division lines 17a.

[0096] After cleaving the single crystal substrate 13 along one of the first planned splitting lines 17a, an external force is similarly applied along another first planned splitting line 17a adjacent to the first planned splitting line 17a that was cleaved immediately before. This causes the single crystal substrate 13 to be cleaved along the other first planned splitting lines 17a. Similarly, the single crystal substrate 13 is cleaved along all of the first planned splitting lines 17a.

[0097] In this embodiment, since a processing groove 25a for promoting cleavage of the single crystal substrate 13 is formed using a laser processing apparatus 2, the depth position of the processing groove 25a in the single crystal substrate 13 becomes easier to control compared to the case where a scribe groove 29 is formed using a diamond scriber.

[0098] When using a diamond scriber, the depth position of the machined groove 25a is relatively difficult to control due to factors such as the material, type, and shape of the cutting edge, the angle at which the cutting edge contacts the surface 13a, and the jumping and landing of the cutting edge during machining.

[0099] In contrast, with the laser processing device 2, the depth of the processing groove 25a can be precisely controlled by parameters such as output and processing feed rate. Therefore, compared to using a diamond scriber, it is possible to suppress the occurrence of undivided regions when dividing the single crystal substrate 13.

[0100] Furthermore, the processing grooves 25a, which are intermittently formed along each first planned division line 17a, function as guides when the single crystal substrate 13 is cleaved in the division step S40. Therefore, even if the longitudinal direction of the processing grooves 25a is formed deviating from a predetermined crystal orientation, the occurrence of diagonal cracks 31a (see Figure 9(B)) that extend beyond the first planned division line 17a can be suppressed.

[0101] Therefore, compared to the conventional method of forming scribe grooves 29 along the planned division line and then applying an external force along the scribe grooves 29 to cleave the single crystal substrate 13, this method can suppress a decrease in yield during the manufacturing of the light-emitting device chip 33 (see Figure 11).

[0102] Here, using Figures 9(A) and 9(B), we will explain the diagonal cracks 31a that occur when a scribe groove 29 is formed along the first planned division line 17a, as in the conventional method. Figure 9(A) shows a continuous scribe groove 29.

[0103] In Figures 9(A) and 9(B), the first planned splitting line 17a is slightly deviated from the first direction 11a (i.e., the first crystal orientation [0-11]). The amount of deviation is the same in Figures 9(C) and 9(D), which will be discussed later.

[0104] When an external force is applied by the braking device 14 with the scribe groove 29 formed, as shown in Figure 8, the single crystal substrate 13 may cleave along the first direction 11a, causing the dividing groove 31 to extend beyond the first planned dividing line 17a and resulting in a crack 31a in an oblique direction (see Figure 9(B)).

[0105] In Figure 9(B), the division groove 31 is shown as a thicker line than the scribe groove 29. Figure 9(B) shows how diagonal cracks 31a occur. If the diagonal cracks 31a cause the division groove 31 to extend beyond the first planned division line 17a or reach the light-emitting element 15, it results in a manufacturing defect for the light-emitting device chip 33, which reduces the yield.

[0106] In contrast, Figures 9(C) and 9(D) illustrate how the intermittent processing grooves 25a formed through the laser beam irradiation step S20 according to this embodiment function as guides during cleavage.

[0107] Figure 9(C) shows the intermittent machining grooves 25a, and Figure 9(D) shows how the single crystal substrate 13 is divided using the intermittent machining grooves 25a as guides. In both Figure 9(C) and Figure 9(D), the first planned division line 17a is slightly offset from the first direction 11a.

[0108] However, as shown in Figure 9(D), since the divided groove 31 is formed so that the region between the two processed grooves 25a is connected to the processed grooves 25a, the divided groove 31 does not reach the light-emitting element 15. Therefore, a decrease in the yield of the light-emitting device chip 33 can be suppressed.

[0109] After the splitting step S40, the single crystal substrate 13 is divided into multiple light-emitting device chips (device chips) 33 by applying an external force to each processed groove 25b of the single crystal substrate 13 (second splitting step S50).

[0110] Figure 10(A) is a partial cross-sectional side view showing the second division step S50, and Figure 10(B) is a partial cross-sectional side view showing the second division step S50 viewed from a 90-degree different orientation from Figure 10(A).

[0111] In the second division step S50, a braking device 20 similar to the braking device 14 used in the division step S40 is used. However, in the braking device 20, the lower end 22a of the pressing blade 22 is positioned diagonally with respect to the upper surface 16a of the receiving base 16.

[0112] More specifically, as shown in Figure 10(A), the pressing blade 22 is positioned such that the height position of one end 22b1 at the lower end 22a of the pressing blade 22 is lower than the height position of the other end 22b2. Above the pressing blade 22, a ball screw type first movement mechanism (not shown) is provided for pushing the pressing blade 22 downward, similar to the braking device 14.

[0113] When the first moving mechanism pushes the pressing blade 22 downward, the pressing blade 22 is sequentially pressed against the second planned division line 17b from one end 17b1 to the other end 17b2. As described above, cleavage is less likely to occur in the second direction 11b compared to the first direction 11a, so the single crystal substrate 13 is less likely to be divided in the second planned division line 17b.

[0114] However, in the second division step S50, by sequentially pressing the pressing blade 22 from one end 17b1 to the other end 17b2 of the second division line 17b, the single crystal substrate 13 is partially cleaved in a crystal orientation parallel to the second direction 11b, while also making it easier to divide the single crystal substrate 13 at the pressing position of the lower end 22a of the pressing blade 22. Therefore, the single crystal substrate 13 can be divided approximately parallel to the second division line 17b.

[0115] In this manner, the single crystal substrate 13 is divided into light-emitting device chips 33 using the breaking device 20. Figure 11 is a perspective view of the light-emitting device chip 33.

[0116] In the second splitting step S50, by sequentially pressing the pressing blade 22 from one end 17b1 to the other end 17b2, the occurrence of cracks in an oblique direction can be suppressed compared to when the pressing blade 22 is pressed almost simultaneously over the range from one end 17b1 to the other end 17b2, thereby suppressing a decrease in yield during the manufacturing of the light-emitting device chip 33.

[0117] In this embodiment, the second division step S50 is performed after the division step S40, but the division step S40 may be performed after the second division step S50.

[0118] (Second Embodiment) Next, a second embodiment will be described with reference to Figures 12 to 14. Figure 12 is a cross-sectional view of the workpiece 11 after the laser beam irradiation step S20 in the second embodiment.

[0119] In the second embodiment, in the laser beam irradiation step S20 following the holding step S10, a first processing groove (accelerating region) 25c having a first depth 25c1 is formed at one end 17a1 of each first planned division line 17a from the surface 13a (see Figure 12).

[0120] The end portion 17a1 is a region located on the outer periphery of the single crystal substrate 13 in the longitudinal direction of the first planned division line 17a, more so than the intersection region 13e between the second planned division line 17b, which is located on the outermost periphery of the single crystal substrate 13, and the first planned division line 17a, and corresponds to one of the two end portions 13d described above.

[0121] When forming the first processed groove 25c, the processing conditions used when forming the processed groove 25b described above should be applied. The first depth 25c1 of the first processed groove 25c is 15% to 80%, more preferably 20% to 50%, of the thickness 13c of the single crystal substrate 13.

[0122] In this embodiment, where the thickness 13c of the single crystal substrate 13 is 90 μm, the first depth 25c1 is 30 μm (approximately 33%) from the surface 13a.

[0123] In the second embodiment, a second processing groove (accelerating region) 25d having a second depth 25d1 that is shallower than the first depth 25c1 is intermittently formed in the region other than one end 17a1 of each first planned division line 17a (specifically, the other end 17a2 and each intersecting region 13e).

[0124] When forming the second processed groove 25d, the processing conditions used when forming the processed groove 25a described above should be applied. The second depth 25d1 of the second processed groove 25d is, for example, 5% to 10% of the single crystal substrate 13.

[0125] In the first planned division line 17a, the second machining groove 25d is not connected to the first machining groove 25c and is separate from the first machining groove 25c. The first machining groove 25c and the second machining groove 25d may be formed in any order.

[0126] Then, in the splitting step S40, the braking device 20 shown in Figure 10(A) is used to sequentially press the pressing blades 18 from one end 17a1 to the other end 17a2 of the first planned splitting line 17a (see Figures 13(A) and 13(B)).

[0127] This allows the single crystal substrate 13 to be cleaved and divided along the first planned division line 17a. Figure 13(A) shows the pressing blade 22 being pressed against one end 17a1, and Figure 13(B) shows the pressing blade 22 being pressed against the other end 17a2 side of the one end 17a1.

[0128] By the way, in the splitting step S40, instead of the pressing blade 22 whose lower end 22a is positioned diagonally with respect to the upper surface 16a of the support base 16, a braking device 26 having an annular pressing blade 24 that can rotate around a rotating axis 24a may be used.

[0129] Figure 14(A) shows the situation when the pressing blade 24 of the braking device 26 is pressed against one end 17a1. Figure 14(B) shows the situation when the pressing blade 24 is pressed against the other end 17a2.

[0130] In this way, by rotating the pressing blade 24 and moving it along the first planned division line 17a, the pressing blade 24 can be sequentially pressed from one end 17a1 to the other end 17a2.

[0131] In the second embodiment as well, the light-emitting device chip 33 can be manufactured by performing a second laser beam irradiation step S30 after the laser beam irradiation step S20, followed by the splitting step S40 and the second splitting step S50.

[0132] (Third Embodiment) Next, a third embodiment will be described with reference to Figure 15. Figure 15 is a cross-sectional view of the workpiece 11 after the holding step S10 and the laser beam irradiation step S20 in the third embodiment.

[0133] In holding step S10, the back surface 13b side of the single crystal substrate 13 is held by suction using the chuck table 4 so that the front surface 13a is exposed, as shown in Figure 3. However, the front surface 13a side may also be held by suction using the chuck table 4 so that the back surface 13b is exposed.

[0134] Furthermore, when the surface 13a is held by suction using the chuck table 4, a holding plate (not shown) made of substantially transparent glass and having multiple suction holes capable of transmitting negative pressure is fixed to the recess of the chuck table 4. In addition, by placing the microscope camera unit 12 below this substantially transparent holding plate, the surface 13a can be imaged from below.

[0135] Alternatively, instead of the nearly transparent holding plate, the microscope camera unit 12 shown in Figure 3 may be equipped with an infrared camera. This allows imaging of the front surface 13a side from above, in a manner that penetrates the back surface 13b.

[0136] In the laser beam irradiation step S20 of the third embodiment, instead of using a laser beam L having a wavelength that penetrates the single crystal substrate 13, a laser beam L having a wavelength that penetrates the single crystal substrate 13 is used to perform so-called stealth dicing (SD).

[0137] In this embodiment, where the single-crystal substrate 13 is formed of gallium arsenide, a pulsed laser beam L having a wavelength of 1064 nm is irradiated onto the single-crystal substrate 13. This wavelength can be achieved, for example, by omitting wavelength conversion in the laser beam irradiation unit 6 described above.

[0138] In the laser beam irradiation step S20 of the third embodiment, the focusing point L of the laser beam L P With the part positioned at one end of the first planned division line 17a at a height position near the surface 13a, the chuck table 4 is fed through the machine at a predetermined speed.

[0139] The processing conditions in the laser beam irradiation step S20 may be as follows, but are not limited to this example.

[0140] Wavelength: 1064nm Average output: 0.3W Repeat frequency: 160kHz Machining feed rate: 300 mm / s Number of passes: 1

[0141] In the laser beam irradiation step S20 of this embodiment, instead of the processing grooves 25a, 25b, the first processing groove 25c, and the second processing groove 25d, a fragile region (accelerated region) 25e is formed in a range from the surface 13a to a predetermined depth 25e1, where the strength of the single crystal substrate 13 is reduced compared to the laser beam L irradiation area.

[0142] The vulnerable region 25e includes a region whose crystallinity has been altered by multiphoton absorption, and cracks extending from that region toward the surface 13a and back surface 13b.

[0143] In this embodiment as well, the vulnerable region 25e is intermittently formed along the first division line 17a by controlling the irradiation and non-irradiation of the laser beam L along the first division line 17a.

[0144] In the second laser beam irradiation step S30 following the laser beam irradiation step S20, a processing groove 25b may be formed in the single crystal substrate 13 by ablation processing under the same processing conditions as in the first embodiment, but stealth dicing may also be performed under the following processing conditions.

[0145] Wavelength: 1064nm Average output: 0.3W Repeat frequency: 160kHz Machining feed rate: 300 mm / s Number of passes: 2

[0146] Note that the focusing point L of the laser beam L in the first pass. P When positioned at a predetermined depth, in the second pass, in order to suppress scattering of the laser beam L in the vulnerable region 25e formed in the first pass, the focal point L in the first pass PThe focusing point L of the laser beam L is located at a depth closer to the surface 13a (or the back surface 13b if the back surface 13b is exposed upwards) than the height position of the surface 13a (or the back surface 13b if the back surface 13b is exposed upwards). P To position it.

[0147] By increasing the number of passes in this way, it becomes easier to cleave the single crystal substrate 13 in the second direction 11b, which is more difficult to cleave in than the first direction 11a. Note that the number of passes is not limited to 2, but may be 3 or more.

[0148] The light-emitting device chip 33 can be manufactured by performing the splitting step S40 and the second splitting step S50 after the laser beam irradiation step S20 and the second laser beam irradiation step S30. The contents described in the first and second embodiments can be applied to the splitting step S40 and the second splitting step S50.

[0149] (Fourth Embodiment) Next, the fourth embodiment will be described with reference to Figure 16. Figure 16 is a cross-sectional view of the workpiece 11 after the holding step S10 and the laser beam irradiation step S20 in the fourth embodiment.

[0150] In the fourth embodiment, in the laser beam irradiation step S20 following the holding step S10, a first vulnerable region (enhancing region) 25f having a first depth 25f1 from the surface 13a is formed at one end 17a1 of each first planned division line 17a.

[0151] When forming the first vulnerable region 25f, the processing conditions used when forming the two or more vulnerable regions 25e described above should be applied. The first depth 25f1 of the first vulnerable region 25f is 15% to 80% of the single crystal substrate 13, more preferably 20% to 50%.

[0152] Furthermore, in the fourth embodiment, a second vulnerable region (enhancing region) 25g having a second depth 25g1 that is shallower than the first depth 25f1 is intermittently formed in the region other than one end 17a1 of each first planned division line 17a (specifically, the other end 17a2 and each intersection region 13e).

[0153] When forming the second vulnerable region 25g, the processing conditions used when forming the vulnerable region 25e described above should be applied. The second depth 25g1 of the second vulnerable region 25g is, for example, 5% to 10% of the single crystal substrate 13.

[0154] Furthermore, the second vulnerable region 25g, which is closest to the first vulnerable region 25f on the first planned division line 17a, is not connected to the first vulnerable region 25f and is located separately.

[0155] In the splitting step S40 following the laser beam irradiation step S20 and the second laser beam irradiation step S30, the braking device 20 is used to sequentially press the pressing blades 18 from one end 17a1 to the other end 17a2 of the first planned splitting line 17a (see Figures 13(A), 13(B), 14(A), and 14(B)).

[0156] This allows the single crystal substrate 13 to be cleaved and divided along the first planned division line 17a. After the division step S40, the second division step S50 is performed to manufacture the light-emitting device chip 33.

[0157] (Fifth Embodiment) Next, the fifth embodiment will be described with reference to Figure 17. Figure 17 shows the laser beam irradiation step S20 after the holding step S10 in the fifth embodiment.

[0158] In the laser beam irradiation step S20 of the fifth embodiment, when intermittently forming processing grooves 25a along each first planned division line 17a, processing grooves 25a are formed by ablation in multiple non-intersecting regions 13f, excluding multiple intersecting regions 13e where multiple first planned division lines 17a and multiple planned division lines 17b intersect.

[0159] The non-intersecting region 13f includes a linear region between adjacent intersecting regions 13e and an end region 13d. In this embodiment as well, since a laser processing device is used, the depth position of the processing groove 25a in the single crystal substrate 13 becomes easier to control, and furthermore, since the processing groove 25a is formed intermittently, the occurrence of diagonal cracks that extend beyond the first planned division line 17a can be suppressed.

[0160] In the fifth embodiment as well, after the laser beam irradiation step S20, the light-emitting device chip 33 can be manufactured by sequentially performing the steps from the second laser beam irradiation step S30 to the second splitting step S50, similar to the first embodiment.

[0161] In particular, in the fifth embodiment, since no processing groove 25a is formed in the intersection region 13e, the single crystal substrate 13 is divided by pure cleavage alone without any processing marks from the ablation process being formed in the intersection region 13e.

[0162] Therefore, compared to the case where a processing groove 25a is formed in the intersection region 13e and then the single crystal substrate 13 is divided, there is an advantage in that chipping in the region corresponding to the intersection region 13e is less likely to occur in the light-emitting device chip 33.

[0163] In addition, in the laser beam irradiation step S20 of this embodiment, as in the second embodiment (Figure 12), a first processing groove 25c having a first depth 25c1 may be formed at one end 17a1, and a second processing groove 25d having a second depth 25d1 that is shallower than the first depth 25c1 may be intermittently formed in each non-intersecting region 13f other than the one end 17a1.

[0164] Furthermore, in the division step S40 of this embodiment, as in the second embodiment (Figures 13(A), 13(B), 14(A), and 14(B)), the pressing blade 18 may be sequentially pressed against the first planned division line 17a from one end 17a1 toward the other end 17a2.

[0165] By the way, in the laser beam irradiation step S20 of this embodiment, instead of forming the processed groove 25a etc. by ablation processing, the vulnerable region 25e, the first vulnerable region 25f, and the second vulnerable region 25g may be formed by stealth dicing, as in the third embodiment (Figure 15) and the fourth embodiment (Figure 16).

[0166] (Sixth Embodiment) Next, with reference to Figure 18(A), the sixth embodiment will be described. In the sixth embodiment, after the holding step S10, a first processing groove (accelerating region) 25c having a first depth 25c1 is formed from the surface 13a at one end 17a1 of each first planned division line 17a, similar to Figure 12 (laser beam irradiation step S20).

[0167] However, in the laser beam irradiation step S20 of the sixth embodiment, instead of intermittently forming the processing grooves 25a along each first planned division line 17a, the first processing groove 25c is formed by ablation processing only at one end 17a1 in the range from the surface 13a to a first depth 25c1 (a predetermined depth).

[0168] Figure 18(A) is a cross-sectional view of the workpiece 11 after the holding step S10 and the laser beam irradiation step S20 in the sixth embodiment. In the laser beam irradiation step S20 and the splitting step S40 after the second laser beam irradiation step S30, a braking device 20 (Figure 13(A)) or a braking device 26 (Figure 14(A)) is used.

[0169] In other words, in the splitting step S40, the pressing blade 22 or pressing blade 24 is sequentially pressed against each first planned splitting line 17a from one end 17a1 toward the other end 17a2. This applies an external force to the single crystal substrate 13, causing it to cleave along each first planned splitting line 17a and thus splitting the single crystal substrate 13.

[0170] In the sixth embodiment as well, since the first processing groove 25c is formed using the laser processing apparatus 2, the depth position of the first processing groove 25c in the single crystal substrate 13 is easier to control compared to the case where the scribe groove 29 is formed using a diamond scriber. Therefore, it is possible to suppress the occurrence of undivided regions when dividing the single crystal substrate 13.

[0171] Furthermore, the first processing groove 25c formed on one end 17a1 in the laser beam irradiation step S20 acts as a trigger for cleavage, and the single crystal substrate 13 is cleaved along the linear region to which the pressing blade 22 or pressing blade 24 is sequentially pressed from one end 17a1 to the other end 17a2.

[0172] In contrast, when the pressing blade 18 is pressed against the back surface 13b of the single crystal substrate 13 on which the scribe groove 29 is formed, a slight deviation of the first planned division line 17a from the first direction 11a may cause a crack 31a in an oblique direction (see Figure 8(B)).

[0173] However, as in this embodiment, by sequentially pressing the pressing blade 22 or pressing blade 24 from one end 17a1 to the other end 17a2, the single crystal substrate 13 can be sequentially cleaved at the pressing positions of the pressing blade 22 or pressing blade 24. Therefore, the occurrence of cracks 31a in an oblique direction can be suppressed.

[0174] In the sixth embodiment as well, after the division step S40, the light-emitting device chip 33 can be manufactured by performing the second division step S50, similar to the first embodiment.

[0175] (Seventh Embodiment) Next, the seventh embodiment will be described with reference to Figure 18(B). Figure 18(B) is a cross-sectional view of the workpiece 11 after the holding step S10 and the laser beam irradiation step S20 in the seventh embodiment.

[0176] In the laser beam irradiation step S20 of the seventh embodiment, a first vulnerable region (enhancement region) 25f having a first depth 25f1 is formed by stealth dicing only at one end 17a1 of each first planned division line 17a from the surface 13a. This point differs from the sixth embodiment, but all other points are the same as the sixth embodiment.

[0177] Although embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the scope described in the embodiments above. The structures, methods, etc., of the embodiments described above can be modified as appropriate and implemented without departing from the scope of the object of the present invention.

[0178] In the above-described embodiment, the case was explained in which the longitudinal direction of the first planned division line 17a is set along the first direction 11a, and the longitudinal direction of the second planned division line 17b is set along the second direction 11b.

[0179] However, in the second planned division line 17b, the pressing blade 22 or pressing blade 24 is pressed sequentially from one end 17b1 to the other end 17b2, making it easier to cleave or divide by means other than cleavage compared to when the pressing blade 18 is pressed approximately perpendicular to the back surface 13b. Therefore, the longitudinal direction of the second planned division line 17b does not have to be set along a crystal orientation that allows for cleavage. [Explanation of symbols]

[0180] 2: Laser processing machine, 4: Chuck table 6: Laser beam irradiation unit, 8: Housing 10: Irradiation head, 12: Microscope camera unit 11: Workpiece, 11a: First direction, 11b: Second direction 13: Single crystal substrate, 13a: Front surface (one side), 13b: Back surface (other side), 13c: Thickness 13d: edge region, 13e: crossing region, 13f: non-crossing region, 15: light-emitting element 14: Braking device, 16: Support base, 16a: Top surface, 16b: Recess 17a: First planned division line, 17a1: one end, 17a2: the other end 17b: Second planned division line, 17b1: one end, 17b2: the other end 18: Pressing blade, 18a: Lower end 19: Protective tape, 19a: Release paper, 21: Ring frame, 23: Workpiece unit 20: Braking device 22: Pressing blade, 22a: Lower end, 22b1: One end, 22b2: Other end 24: Pressing blade, 24a: Rotating shaft, 26: Braking device 25a: Machining groove (accelerated area), 25a1: Depth 25b: Machined groove (starting point of division), 25b1: Depth 25c: First machining groove (accelerated area), 25c1: First depth (predetermined depth) 25d: Second machining groove (accelerated area), 25d1: Second depth 25e: Vulnerable region (facilitated region), 25e1: Depth 25f: First vulnerable region (facilitation region), 25f1: First depth 25g: Second vulnerable region (facilitation region), 25g1: Second depth 29: Scrib groove, 31: Split groove, 31a: Diagonal crack 33: Light-emitting device chip (device chip) L: Laser beam, L P : Focusing point S10: Holding step S20: Laser beam irradiation step (first laser beam irradiation step) S30: Second laser beam irradiation step S40: Splitting step (First splitting step) S50: Second split step

Claims

1. A method for dividing a single crystal substrate by cleaving it, A holding step of holding a single crystal substrate, which has multiple planned division lines along a first direction set on one surface so as to be aligned with a predetermined crystal orientation that allows the single crystal substrate to be cleaved, in a chuck table of a laser processing apparatus, After the holding step, a laser beam irradiation step is performed in which a laser beam is irradiated from the laser beam irradiation unit of the laser processing apparatus along each planned division line to intermittently form promotion regions along each planned division line for promoting cleavage of the single crystal substrate, The process includes a splitting step in which, after the laser beam irradiation step, an external force is applied to the single crystal substrate to split it along each planned splitting line, thereby splitting the single crystal substrate. In this holding step, the other side of the single crystal substrate, which is located opposite to the one side, is held by the chuck table. In the laser beam irradiation step, a laser beam having a wavelength absorbed by the single crystal substrate is irradiated to intermittently form processing grooves having a depth that does not completely cut the single crystal substrate, along each planned division line as the promotion region, A first processing groove having a first depth from that surface is formed as the acceleration region at one end of each planned division line in the first direction, and a second processing groove having a second depth shallower than the first depth is intermittently formed as the acceleration region in the region other than the one end of each planned division line. The splitting method is characterized in that, in the splitting step, the single crystal substrate is split by sequentially pressing a pressing blade from one end toward the other end located on the opposite side of the first end.

2. A method for dividing a single crystal substrate by cleaving it, A holding step of holding a single crystal substrate, which has multiple planned division lines along a first direction set on one surface so as to be aligned with a predetermined crystal orientation that allows the single crystal substrate to be cleaved, in a chuck table of a laser processing apparatus, After the holding step, a laser beam irradiation step is performed in which a laser beam is irradiated from the laser beam irradiation unit of the laser processing apparatus along each planned division line to intermittently form promotion regions along each planned division line for promoting cleavage of the single crystal substrate, The process includes a splitting step in which, after the laser beam irradiation step, an external force is applied to the single crystal substrate to split it along each planned splitting line, thereby splitting the single crystal substrate. In the laser beam irradiation step, a laser beam having a wavelength that penetrates the single crystal substrate is irradiated to intermittently form a weakened region along each planned division line, which is the enhancement region, in which the strength of the single crystal substrate is reduced. A first vulnerable region having a first depth from that surface is formed as the reinforcement region at one end of each planned division line in the first direction, and a second vulnerable region having a second depth shallower than the first depth is intermittently formed as the reinforcement region in the region other than the one end of each planned division line. A method for dividing a single crystal substrate, characterized in that, in the dividing step, the single crystal substrate is divided by sequentially pressing a pressing blade from one end toward the other end located on the opposite side of the one end.

3. On one surface of the single crystal substrate, a plurality of division lines are further set along a second direction perpendicular to the first direction. The method for dividing a single crystal substrate according to claim 1 or 2, characterized in that, in the laser beam irradiation step, when the promotion region is intermittently formed along each of the planned division lines in the first direction, the promotion region is formed in each of the plurality of intersection regions where the plurality of planned division lines along the first direction and the plurality of planned division lines along the second direction intersect.

4. On one surface of the single crystal substrate, a plurality of division lines are further set along a second direction perpendicular to the first direction. The method for dividing a single crystal substrate according to claim 1 or 2, characterized in that, in the laser beam irradiation step, when the promotion region is intermittently formed along each planned division line in the first direction, the promotion region is formed in a region excluding a plurality of intersection regions where a plurality of planned division lines along the first direction and a plurality of planned division lines along the second direction intersect.

5. A method for manufacturing device chips, which involves dividing a single crystal substrate to produce multiple device chips, A holding step of holding a single crystal substrate with a chuck table of a laser processing apparatus, wherein a plurality of division lines arranged in a grid along a first direction and a second direction that intersect each other are set on one surface such that a plurality of division lines along the first direction are aligned with a predetermined crystal orientation that allows the single crystal substrate to be cleaved, A first laser beam irradiation step is performed, in which a laser beam is irradiated from the laser beam irradiation unit of the laser processing apparatus along each of the planned division lines in the first direction to intermittently form promotion regions along each of the planned division lines in the first direction for promoting cleavage of the single crystal substrate, A second laser beam irradiation step is performed, in which a laser beam is irradiated from the laser beam irradiation unit onto the single crystal substrate along a plurality of planned division lines in the second direction, thereby forming division starting points along each of the planned division lines in the second direction. A first splitting step is performed in which, after the first laser beam irradiation step and the second laser beam irradiation step, an external force is applied to the promotion region of the single crystal substrate to cleave the single crystal substrate along each planned splitting line in the first direction, The method comprises a first laser beam irradiation step and a second laser beam irradiation step, followed by a second splitting step in which an external force is applied to the splitting starting point of the single crystal substrate to split the single crystal substrate, After the first and second division steps, the single crystal substrate is divided into the plurality of device chips. In this holding step, the other side of the single crystal substrate, which is located opposite to the one side, is held by the chuck table. In the first laser beam irradiation step, a laser beam having a wavelength absorbed by the single crystal substrate is irradiated to intermittently form processing grooves having a depth that does not completely cut the single crystal substrate, along each planned division line as the acceleration region, A first processing groove having a first depth from that surface is formed as the acceleration region at one end of each planned division line in the first direction, and a second processing groove having a second depth shallower than the first depth is intermittently formed as the acceleration region in the region other than the one end of each planned division line. A method for manufacturing a device chip, characterized in that in the first splitting step, the single crystal substrate is split by sequentially pressing a pressing blade from one end toward the other end located on the opposite side of the first end.

6. A method for manufacturing a device chip by dividing a single crystal substrate to produce a plurality of device chips, A holding step of holding a single crystal substrate with a chuck table of a laser processing apparatus, wherein a plurality of division lines arranged in a grid along a first direction and a second direction that intersect each other are set on one surface such that a plurality of division lines along the first direction are aligned with a predetermined crystal orientation that allows the single crystal substrate to be cleaved, A first laser beam irradiation step is performed, in which a laser beam is irradiated from the laser beam irradiation unit of the laser processing apparatus along each of the planned division lines in the first direction to intermittently form promotion regions along each of the planned division lines in the first direction for promoting cleavage of the single crystal substrate, A second laser beam irradiation step is performed, in which a laser beam is irradiated from the laser beam irradiation unit onto the single crystal substrate along a plurality of planned division lines in the second direction, thereby forming division starting points along each of the planned division lines in the second direction. A first splitting step is performed in which, after the first laser beam irradiation step and the second laser beam irradiation step, an external force is applied to the promotion region of the single crystal substrate to cleave the single crystal substrate along each planned splitting line in the first direction, The method comprises a first laser beam irradiation step and a second laser beam irradiation step, followed by a second splitting step in which an external force is applied to the splitting starting point of the single crystal substrate to split the single crystal substrate, After the first and second division steps, the single crystal substrate is divided into the plurality of device chips. In the first laser beam irradiation step, a laser beam having a wavelength that penetrates the single crystal substrate is irradiated to intermittently form a weakened region along each planned division line, which is the enhancement region, in which the strength of the single crystal substrate is reduced. A first vulnerable region having a first depth from that surface is formed as the reinforcement region at one end of each planned division line in the first direction, and a second vulnerable region having a second depth shallower than the first depth is intermittently formed as the reinforcement region in the region other than the one end of each planned division line. In the first splitting step, the single crystal substrate is split by sequentially pressing the pressing blades from one end toward the other end located on the opposite side of the first end. A method for manufacturing a device chip characterized by the following:

7. In the laser beam irradiation step, the enhancement region is formed at one end of the planned division line in the first direction, extending from that surface to a predetermined depth. A method for dividing a single crystal substrate according to claim 1 or 2, further comprising a dividing step of dividing the single crystal substrate by sequentially pressing a pressing blade against the single crystal substrate from one end toward the other end located opposite to the one end, after the laser beam irradiation step, thereby applying an external force to the single crystal substrate and dividing the single crystal substrate by cleaving it along the planned dividing line.

8. The predetermined depth is 15% to 80% of the thickness of the single crystal substrate from one surface to the other surface located opposite to that surface. The method for dividing a single crystal substrate according to claim 7, characterized in that the laser beam irradiation step involves forming the enhancement region at one end in a range from one surface to a predetermined depth.

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