JP2021185594A - Method of manufacturing light-emitting element - Google Patents

Abstract

To provide a method of manufacturing a light-emitting element, improved in ease of cleaving a substrate.SOLUTION: There is provided a method of manufacturing a light-emitting element in which a laser beam is condensed inside a substrate 50 provided with a semiconductor structure 11 to form a plurality of modified portions and then the substrate 50 is cleaved. The method of manufacturing a light-emitting element includes the steps of: scanning the substrate with a laser beam along a predetermined planned cleavage line PC to perform first irradiation to form the plurality of first modified portions 21 located on the planned cleavage line PC inside the substrate 50 and cracks generated from the first modified portions 21; after the first irradiation, scanning the substrate with a laser beam along a first virtual line VL1 that is parallel to the planned cleavage line PC in a top view and is offset in a plane direction of the substrate 50 by a predetermined distance to perform second irradiation to form a plurality of second modified portions 22 located on the first virtual line VL1 inside the substrate 50; and facilitating development of the cracks generated from the first modified portions 21 by cleaving the substrate 50 starting from the plurality of first modified portions 21.SELECTED DRAWING: Figure 7

Description

The present invention relates to a method for manufacturing a light emitting element.

Semiconductor light emitting devices are small, power efficient, and emit bright colors. Further, the semiconductor light emitting device has excellent initial drive characteristics and is resistant to vibration and repeated on / off lighting. Due to such excellent characteristics, semiconductor light emitting devices such as light emitting diodes (hereinafter also referred to as "LEDs") and laser diodes are used as various light sources to further improve the luminous output and emit light. There is a need to improve efficiency.

Such a semiconductor light emitting device can be obtained by epitaxially growing a semiconductor layer on a sapphire substrate or the like and then dividing the semiconductor layer. As a method of dividing a sapphire substrate on which a semiconductor layer is laminated, for example, in Patent Document 1, a modified region is formed inside the sapphire substrate by irradiating a laser beam from the back surface side of the sapphire substrate, and the modified region is formed. A method of cutting by causing a crack from the sapphire has been proposed. Further, when the sapphire substrate is thickened, the cutting may be insufficient only by providing one modified region inside the sapphire substrate. Therefore, a method has been proposed in which laser irradiation is further performed to provide two or three or more modified regions in the thickness direction of the sapphire substrate and cut them.

However, if a plurality of such modified regions are provided in the thickness direction of the sapphire substrate, the portion where the laser light is focused approaches the semiconductor layer, and the laser light may deteriorate the semiconductor layer. However, if only one modified region is provided in the thickness direction of the substrate, the division becomes insufficient as described above. As described above, the splittability of the sapphire substrate and the suppression of deterioration of the semiconductor layer are in conflict with each other, and it is difficult to achieve both of them.

Japanese Unexamined Patent Publication No. 2006-245062

The present invention has been made to solve such conventional problems. An object of the present invention is to provide a method for manufacturing a light emitting element having improved ease of cutting of a substrate.

In order to achieve the above object, according to the method for manufacturing a light emitting device according to an embodiment of the present invention, a plurality of modified portions are formed by condensing laser light inside a substrate on which a semiconductor structure is formed. After that, it is a method of manufacturing a light emitting element that cuts the substrate by scanning a laser beam along a preset scheduled cut line, and a plurality of first modifications located inside the substrate on the scheduled cut line. After the first irradiation to form the quality part and the crack generated from the first reforming part, and after the first irradiation, a predetermined amount is parallel to the planned split line in the top view and is in the plane direction of the substrate. A step of scanning the laser beam along the shifted first virtual line and performing a second irradiation to form a plurality of second reforming portions located on the first virtual line inside the substrate, and a plurality of the first. (I) A step of promoting the extension of the crack generated from the first modified portion by cutting the substrate starting from the modified portion can be included.

By the method for manufacturing a light emitting element according to an embodiment of the present invention, the second reformed portion is formed along the first virtual line different from the planned cutting line, thereby promoting the extension of cracks from the first modified portion. It is possible to easily cut the substrate.

It is a schematic sectional drawing which shows the light emitting element obtained by the manufacturing method which concerns on Embodiment 1. FIG. It is a schematic cross-sectional view which shows the state of dividing a substrate into a light emitting element. It is a schematic plan view which shows the scanning direction of a laser beam with respect to a substrate. It is a schematic cross-sectional view which shows the state which formed the reforming part along a plurality of planned cutting lines. FIG. 5A is a schematic plan view showing how the laser beam is irradiated to the same portion of the substrate a plurality of times by the method according to the comparative example, and FIG. 5B is a state where the scanning position is shifted for each scan by the method according to the first embodiment. It is a schematic plan view which shows. 6A is a schematic cross-sectional view of the substrate of FIG. 5A, and FIG. 6B is a schematic cross-sectional view of the substrate of FIG. 5B. FIG. 7A is a schematic plan view showing an irradiation pattern of laser light radiated onto the substrate by the method according to the second embodiment, and FIG. 7B is a cross-sectional view of the substrate of FIG. 7A. FIG. 8A is a schematic plan view showing an irradiation pattern of laser light radiated onto the substrate by the method according to the third embodiment, and FIG. 8B is a schematic cross-sectional view of the substrate of FIG. 8A. It is a graph which shows the result of having measured the length of a crack by scanning a laser beam by the method which concerns on Examples 1 and 2 and Comparative Examples 1 and 2. 3 is a graph showing the crack length when the offset amount of the laser beam is changed by the methods according to Examples 3 to 7 and Comparative Example 3. FIG. 11A is a plan photograph showing a modified region of a substrate irradiated with laser light by the method according to Comparative Example 3, and FIG. 11B is a plan photograph showing a modified region of a substrate irradiated with laser light by the method according to Example 4. 11C is a plan photograph showing a modified region of a substrate irradiated with laser light by the method according to Example 6, FIG. 11D is a photograph showing a substrate cross section of FIG. 11A, and FIG. 11E is a photograph showing a substrate cross section of FIG. 11B. 11F is a photograph showing a cross section of the substrate of FIG. 11C. It is a schematic plan view of the substrate which made the orientation flat surface coincide with the horizontal plane. It is a schematic plan view which shows the plurality of reforming parts formed with respect to the planned cutting line, and the plurality of reforming parts formed by offsetting in the + direction and the − direction from the planned cutting line. FIG. 14A is a schematic perspective view showing an example in which the first virtual line is set on the left side with respect to the planned cutting line, and FIG. 14B is a schematic perspective view showing an example in which the first virtual line is set on the right side with respect to the planned cutting line. be. FIG. 15A is a micrograph showing the surface of the substrate in an example in which the first virtual line is shifted by +5 μm from the planned cutting line, and FIG. 15B is a micrograph showing the surface of the substrate in an example in which the first virtual line is shifted by -5 μm from the planned cutting line. Is. FIG. 16A is a schematic perspective view showing an example in which the second pass is offset in the + direction from the first pass, and FIG. 16B is a schematic perspective view showing an example in which the second pass is offset in the − direction from the first pass. FIG. 17A is a micrograph showing an example in which the second pass is offset by 5 μm in the + direction from the first pass, and FIG. 17B is a micrograph showing an example in which the second pass is offset by 5 μm in the + direction from the first pass, FIG. 17C. Is a micrograph showing an example in which the second pass is offset by 5 μm in the − direction from the first pass, and FIG. 17D is a micrograph showing an example in which the second pass is offset by 5 μm in the − direction from the first pass. 18A is a schematic cross-sectional view of the substrate in FIG. 16A, and FIG. 18B is a schematic cross-sectional view of the substrate in FIG. 16B. It is a schematic plan view of the substrate in which the orientation flat surface is inclined by 45 ° from the horizontal plane. FIG. 20A is a schematic enlarged plan view showing the shape of processing marks when laser light is scanned from left to right along the left-right direction on the substrate and irradiated in a pulse shape, and FIG. 20B is the substrate obtained by scanning FIG. 20A. 20C is a schematic enlarged plan view showing the shape of the processing mark when the laser beam is scanned from right to left along the left-right direction and irradiated in a pulse shape on the substrate, and FIG. 20D is a scanning of FIG. 20C. It is a micrograph of the substrate which performed. FIG. 21A is a schematic enlarged plan view showing the extension of cracks obtained when the laser beam is scanned in the left-right direction and then offset upward to scan the laser beam, and FIG. 21B is the laser beam scanned in the left-right direction. After that, it is a schematic enlarged plan view which shows the extension of the crack obtained when the laser beam is scanned by offsetting it downward. It is a schematic plan view which shows the light emitting element obtained by individualizing the substrate of FIG. 5B. It is a schematic plan view which shows the other example which shows the irradiation position of a laser beam. It is a schematic plan view which shows the light emitting element obtained by making the substrate of FIG. 23 into pieces. It is an enlarged photograph of an individualized light emitting element.

Hereinafter, embodiments will be described in detail based on the drawings. However, the embodiments to examples shown below exemplify a method for manufacturing a light emitting device for embodying the technical idea of the present invention, and the present invention is not limited to the following. In particular, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the examples are not intended to limit the scope of the present invention to that alone, and are merely explanatory examples. It's just that. The size and positional relationship of the members shown in each drawing may be exaggerated for the sake of clarity. Further, in the following description, members of the same or the same quality are shown with the same name and reference numeral, and detailed description thereof will be omitted as appropriate. Further, each element constituting the present invention may be configured such that a plurality of elements are composed of the same member and the plurality of elements are combined with one member, or conversely, the function of one member is performed by the plurality of members. It can also be shared and realized. Further, in the present specification, the term "upper" as used in terms of layers and the like is not limited to the case where they are formed in contact with the upper surface, but also includes the cases where they are formed apart from each other and above the layers. It is used to include the case where an intervening layer exists between them. Furthermore, the contents described in some examples, embodiments may be available in other embodiments, embodiments and the like. Also, in the following description, terms indicating a specific direction or position (for example, "top", "bottom", and other terms including those terms) are used as needed, but the use of these terms is a drawing. This is for facilitating the understanding of the invention with reference to the above, and the meaning of these terms does not limit the technical scope of the present invention. In addition, in this specification, "providing" is used in the sense of including both those provided as a separate member and those configured as an integral member.
(Light emitting element 10)

First, the light emitting element 10 obtained by the manufacturing method according to the first embodiment of the present invention is shown in a schematic cross-sectional view of FIG. The light emitting element 10 shown in FIG. 1 is a face-up type LED which is an example of a nitride semiconductor element. Hereinafter, the details of the light emitting element 10 will be described.

In the light emitting device 10 of FIG. 1, a semiconductor structure 11 in which a plurality of nitride semiconductor layers are laminated is formed on a first main surface 51 which is one main surface of a substrate 50 having a pair of facing main surfaces. There is. Specifically, the light emitting element 10 has a semiconductor structure in which an n-type semiconductor layer 6, an active region 8, and a p-type semiconductor layer 7 are sequentially provided on the first main surface 51 of the substrate 50 from the first main surface 51 side. 11 is formed. On the n-type semiconductor layer 6, an n-side pad electrode 3A electrically connected to the n-type semiconductor layer 6 is formed. Further, a translucent conductive layer 13 is formed on the p-type semiconductor layer 7. On the translucent conductive layer 13, a p-side pad electrode 3B that is electrically connected to the p-type semiconductor layer 7 via the translucent conductive layer 13 is formed. Further, the surface of the semiconductor structure 11 and the surfaces of the n-side pad electrode 3A and the p-side pad electrode 3B are covered with the insulating protective film 14. A part of the surface of the n-side pad electrode 3A and the p-side pad electrode 3B is exposed from the protective film 14. When power is supplied from the outside, the light emitting element 10 emits light from the active region 8 via the n-side pad electrode 3A and the p-side pad electrode 3B, and mainly emits light from the electrode forming surface side in FIG. Is taken out. That is, in the light emitting element 10 of FIG. 1, the surface side on which the n-side pad electrode 3A and the p-side pad electrode 3B are provided is the main light extraction surface 18. Hereinafter, each component of the light emitting element 10 will be specifically described.
(Board 50)

The size and thickness of the substrate 50 are not particularly limited as long as the substrate 50 is capable of epitaxially growing the semiconductor structure 11. When a nitride semiconductor is epitaxially grown as the semiconductor structure 11, an insulating substrate made of sapphire having any of the C-plane, the R-plane, and the A-plane as the main surface can be used as the substrate 50.
(Semiconductor structure 11)

The semiconductor structure 11, the general formula can be used _{In x Al y Ga 1-xy} N (0 ≦ x, 0 ≦ y, x + y ≦ 1) is a nitride semiconductor. The semiconductor structure 11 has an active region 8 which is a light emitting layer, and the active region 8 can be a single or multiple quantum well structure. The peak wavelength of the light emitted from the active region 8 can be in the range of 360 nm or more and 650 nm or less, preferably in the range of 380 nm or more and 560 nm or less. The n-type semiconductor layer 6 may contain Si, Ge and the like as n-type impurities. Further, the p-type semiconductor layer 7 may contain Mg, Zn and the like as p-type impurities. The concentration of impurities in the nitride semiconductor layer containing impurities is preferably 5 × 10 ¹⁶ / cm ³ or more and 5 × 10 ²¹ / cm ³ or less.
(Translucent conductive layer 13)

As shown in FIG. 1, the translucent conductive layer 13 is formed on the p-type semiconductor layer 7. By forming the translucent conductive layer 13 on the p-type semiconductor layer 7, the current can be spread over a relatively wide range of the p-type semiconductor layer 7.

The translucent conductive layer 13 can be an oxide containing at least one element selected from the group consisting of, for example, Zn, In, and Sn. Specifically, it is desirable to form a translucent conductive layer 13 containing an oxide of Zn, In, Sn such as ITO, ZnO, In ₂ O ₃ , SnO _{2, and the like, and ITO is preferably used.} As a result, good ohmic contact can be obtained to diffuse the current to the semiconductor structure that abuts the light from the active region 8 while transmitting the light.
(Electrode 3)

The n-side pad electrode 3A and the p-side pad electrode 3B are electrically connected to the n-type semiconductor layer 6 and the p-type semiconductor layer 7, respectively. The n-side pad electrode 3A and the p-side pad electrode 3B can be, for example, Au or an alloy containing Au as a main component.
(Protective film 14)

The protective film 14 covers at least the upper surface of the n-type semiconductor layer 6 and the upper surface of the p-type semiconductor layer 7. The protective film 14 has an n-side opening on the upper surface of the n-type semiconductor layer 6 and a p-side opening on the upper surface of the p-type semiconductor layer 7. The protective film 14 also covers the side surfaces of the n-type semiconductor layer 6 and the p-type semiconductor layer 7. In particular, by continuously covering the side surface of the n-type semiconductor layer 6, the side surface of the active region 8, and the side surface of the p-type semiconductor layer 7, the generation of leakage current is prevented. The film thickness of the protective film 14 may be as long as it can protect each semiconductor layer, and is preferably 10 nm or more and 1000 nm or less, and more preferably 100 nm or more and 300 nm or less.
(Manufacturing method of light emitting element)

In the method of manufacturing a light emitting element, first, a substrate 50 made of sapphire and having a first main surface 51 and a second main surface 52 is prepared. The substrate 50 has a substantially circular shape in a plan view, and has an orientation flat surface OF at a part of the peripheral edge. The orientation flat surface OF is preferably the A surface or the C surface. Among them, it is preferable to use a sapphire substrate having the C surface (0001) as the first main surface 51 and the orientation flat surface OF as the A surface (11-20) as the substrate 50. The thickness of the substrate 50 is preferably, for example, 100 μm or more and 800 μm or less, and more preferably 100 μm or more and 300 μm or less.

As described above, the present invention can be suitably used for a sapphire substrate that is difficult to cut. In the following example, an example in which a sapphire substrate is used as the substrate 50 will be described.
(Semiconductor layer forming process)

The semiconductor structure 11 is formed on the first main surface 51 of the substrate 50. The semiconductor structure 11 includes a plurality of semiconductor layers. The growth method of the semiconductor layer is not particularly limited. For example, MOVPE (metalorganic vapor phase growth method), MOCVD (metalorganic chemical vapor deposition method), HVPE (hydride vapor phase growth method), MBE (molecular beam epitaxy method), and the like are known as semiconductor growth methods. All methods can be suitably used. In particular, it is preferable to use MOCVD because the semiconductor layer can be grown with good crystallinity.
(Cut process)

After the semiconductor structure 11 is grown on the first main surface 51 of the substrate 50, for example, the substrate 50 is polished to about 100 μm or more and 300 μm or less. After that, a part of the substrate 50 is modified by condensing the laser beam inside the substrate 50 and partially embrittlement it. The scanning pattern of the laser beam in the cross-sectional view is shown in the schematic cross-sectional view of FIG. As shown in FIG. 2, the laser beam LB is irradiated to the inside of the substrate 50 from the second main surface 52 side of the substrate 50. By irradiating the laser beam LB, the irradiated region is modified to form the modified portion 20. Then, a crack CR is generated from the modified portion 20 toward the first main surface 51 side and the second main surface 52 side of the substrate 50. By scanning the laser beam LB in the plane of the substrate 50 to form the plurality of reforming portions 20, the reforming line 26 in which the plurality of reforming portions 20 are formed in a line shape is formed. By applying stress to the substrate 50, the substrate 50 is cut from the reformed portion 20 and the crack CR as starting points.

While condensing the laser beam inside the substrate 50, it is scanned along a plurality of planned cutting lines PCs shown in FIG. 3, which are scheduled to be cut at the time of individualization. In top view, the scanning of the laser beam LB is a primary direction that is substantially perpendicular to the orientation flat surface OF and a direction that is substantially parallel to the orientation flat surface OF, as shown in FIG. 2. Do this in the next direction and in each direction. For example, the laser beam is scanned along the primary direction and then scanned along the secondary direction. By scanning the laser beam along the plurality of planned cutting lines PCs, the reformed portion 20 along the plurality of scheduled cutting lines PCs is formed as shown in the schematic cross-sectional view shown in FIG. Then, the substrate 50 is cut along the planned cutting line PC and separated into a plurality of light emitting elements.

However, when the substrate 50 is thickened, the crack CR may not be sufficiently extended by the above method, and it may be difficult to cut the substrate 50. Therefore, in order to further promote the expansion of the crack CR, it is conceivable to increase the output of the laser beam LB, but if the output of the laser beam LB is increased too much, the semiconductor layer formed on the substrate 50 will be heated by the laser beam LB or the like. There is a concern that it will deteriorate.
[Embodiment 1]

Therefore, as a result of diligent research, the present inventors have found that the extension of the crack CR can be promoted by devising the irradiation position of the laser beam LB, and have come to the present invention. Specifically, as shown in FIG. 5A, not only the first reforming section 21 is formed by irradiating the laser beam along the planned cutting line PC, but also as shown in FIG. 5B, the location is from the planned cutting line PC. A second reformed portion 22 is formed inside the substrate 50 by irradiating a laser beam along the first virtual line VL1 shifted by a fixed amount. Here, the irradiation position of the laser beam in the cross-sectional view is shown in the cross-sectional views of FIGS. 6A and 6B. FIG. 6A shows an irradiation pattern of a comparative example corresponding to FIG. 5A, and FIG. 6B shows an irradiation pattern according to the first embodiment corresponding to FIG. 5B. In the irradiation of the laser beam according to the first embodiment, as shown in FIG. 6B, while irradiating the laser beam at substantially the same position in the thickness direction of the substrate 50 on the planned cut line PC and the first virtual line VL1, FIG. 5B As shown in the above, the laser beam is applied to the planned cut line PC and the first virtual line VL1. By doing so, the extension of the crack CR from the first reformed portion 21 formed along the planned cutting line PC can be promoted, and the substrate 50 can be efficiently cut.

Normally, the strain generated during the formation of the modified portion 20 is released, so that cracks are generated from the modified portion 20. However, when the modified portion 20 is newly formed in the vicinity of the region where the modified portion 20 is formed and the crack has already occurred, the force generated when the strain is released contributes most to the generation of the new crack. It is presumed that it mainly works for cracks that have already occurred. That is, in the first embodiment, the force generated when the strain generated when forming the second reforming portion 22 is released acts on the crack CR from the already formed first reforming portion 21. It is presumed that the extension of the crack CR is promoted.

FIG. As shown in 6B, the width W2 of the finally formed modified region becomes large.

The process of cutting the substrate 50 in this way will be described. First, the first irradiation for scanning the laser beam LB along the planned cutting line PC is performed, and from the plurality of first reforming units 21 located on the planned cutting line PC and the first reforming unit 21 inside the substrate 50. Form cracks and cracks. Then, following the first irradiation, a second irradiation is performed in which the laser beam is scanned along the first virtual line VL1 which is parallel to the planned cutting line PC in the top view of the substrate 50 and is shifted by a predetermined amount in the plane direction of the substrate 50. conduct. As a result, a plurality of second reforming portions 22 located on the first virtual line VL1 are formed inside the substrate 50, and the extension of cracks generated from the first reforming portion 21 is promoted. Then, the substrate 50 is cut from the plurality of first reforming portions 21 as starting points.

Here, it is preferable that the output of the laser beam in the second irradiation is equal to or higher than the output of the laser beam in the first irradiation. As a result, the force due to the release of the strain generated during the formation of the second reforming portion 22 can be further increased, and the expansion of cracks from the first reforming portion 21 can be easily promoted.

The first virtual line VL1 is preferably located at a position shifted from the planned cutting line PC by 3 μm or more and 7 μm or less in the plane direction of the substrate. By setting the amount of shifting the first virtual line VL1 from the planned cutting line PC in the plane direction of the substrate to 3 μm or more, it is possible to efficiently promote the extension of cracks from the first reforming section 21. By setting the amount of the first virtual line VL1 to be shifted from the planned cutting line PC in the plane direction of the substrate to 7 μm or less, the extension of the crack CR from the first reforming section 21 is promoted, and the second reforming section 22 The occurrence of cracks can be suppressed.

It is preferable that the focusing position of the laser light in the second irradiation is about the same as the focusing position of the laser light in the first irradiation in the thickness direction of the substrate. As a result, the action of promoting the extension of the crack CR from the first reforming section 21 by the second reforming section 22 described above can be effectively generated.

As the laser beam LB, various lasers such as a laser that generates a pulsed laser and a continuous wave laser that can cause multiphoton absorption can be used. Examples of the pulse width of the pulsed laser beam include 100 fsec to 1000 psec. Further, as the peak wavelength of the laser beam, a peak wavelength capable of transmitting through the substrate 50 made of sapphire is selected. For example, the peak wavelength of the laser beam is in the range of 350 nm or more and 1100 nm or less. Examples of the laser having a wavelength capable of transmitting the substrate 50 made of sapphire include Nd: YAG laser, Yb: YAG laser, Nd: YVO ₄ laser, Nd: YLF laser, titanium sapphire laser, and KGW laser. The laser spot diameter of the laser beam is, for example, 1 μm or more and 10 μm or less.

FIG. 22 shows a schematic plan view of the light emitting element 10 which is cut into pieces by cutting the substrate 50 shown in FIG. 5B along the planned cutting line PC. The light emitting element 10 shown in FIG. 22 is a light emitting element located at the lower right in FIG. 5B. In the light emitting element 10 which is fragmented into a rectangular shape in this way, a second modified portion is formed along a part of four sides defining the outer edge of the light emitting element 10 in a plan view. In FIG. 22, the second reforming portion 22 is formed along two adjacent sides of the upper side and the left side of the rectangular shape.

Further, in the example of FIG. 5B, the first virtual line VL1 is irradiated with a laser beam along each of the planned cut line PCs for dividing the substrate 50 vertically and horizontally, and the second reforming unit 22 is formed. Although the example of forming has been described, the present invention is not limited to this configuration, and the second modified portion 22 may be formed for only one of the vertical and horizontal laser beams scanned vertically and horizontally. An example of such a situation is shown in the schematic plan view of FIG. In this example, the first virtual line VL1 is set along the planned cutting line PC extending in the lateral direction in the figure, and the laser light is scanned by the planned cutting line PC and the first virtual line VL1 to scan the first reforming unit 21. And the second reforming section 22 is formed. As for the planned cutting line PC'extending in the vertical direction, the laser beam is scanned only on the planned cutting line PC'to form only the first reforming section 21. As shown in the schematic plan view of FIG. 24, the light emitting element 10B obtained by cutting the substrate 50 scanned by the laser beam into pieces is provided on only one of the four sides (upper side in FIG. 24). A second reforming section 22 is formed along the line.

Further, an enlarged photograph of the light emitting element 10 thus obtained is shown in FIG. 25. FIG. 25 is an enlarged photograph of a part of the upper side of the outer edge of the light emitting element 10 shown in FIG. 22. Here, a sapphire substrate was used as the substrate 50. A femtosecond laser having a pulse width of 700 fs was used as the laser beam. The output of the first irradiation of the laser beam was 0.15 W, and the output of the second irradiation was 0.25 W. The offset amount between the first irradiation and the second irradiation was 6 μm. FIG. 25 shows an optical micrograph (transmitted illumination to which illumination light is applied from the back surface side) seen from the back surface side of the sapphire substrate by cutting the substrate 50 to obtain a light emitting element 10. Further, the focal position of the optical microscope is set to be the region of the second reforming portion 22 inside the substrate 50. As shown in FIG. 25, it can be confirmed that the second reforming portion 22 is formed inward from the outer edge along the outer edge.
[Embodiment 2]

In the first embodiment, an example in which the laser beam is scanned twice in the parallel direction of the substrate 50 at different irradiation positions has been described. However, in the present invention, the number of times the laser beam is scanned is not limited to two, and may be three or more. As an example, a method of scanning the laser beam three times is shown in the plan view of FIG. 7A and the cross-sectional view of FIG. 7B as the second embodiment. As shown in these figures, following the second irradiation, the second virtual line shifted in the plane direction of the board 50 on the side opposite to the first virtual line VL1 with respect to the planned split line PC in the top view of the board 50. The laser beam is scanned along the line VL2. By such third irradiation, a plurality of third modified portions 23 located on the second virtual line VL2 are formed inside the substrate 50, and the extension of crack CR from the first modified portion 21 is promoted. .. According to this method, as compared with the first embodiment described above, not only the second reforming section 22 but also the force generated during the formation of the third reforming section 23 is released from the first reforming section 21. By acting on the crack CR, the extension of the crack CR can be further promoted. As shown in FIG. 7B, the width W3 of the reformed region finally formed in the second embodiment is larger than the width W2 of the reformed region finally formed in the first embodiment shown in FIG. 6B. In the examples of FIGS. 7A and 7B, for the sake of explanation, an example in which the first virtual line VL1 is arranged on the left side of the planned cutting line PC and the second virtual line VL2 is arranged on the right side is described. It is preferable to appropriately change which side of the line VL2 is arranged on the left or right side with respect to the planned cutting line PC, depending on the conditions of the sapphire substrate and the like.

The output of the laser beam in the third irradiation is preferably equal to or higher than the output of the laser beam in the first irradiation. As a result, the force due to the release of the strain generated during the formation of the third reforming portion 23 can be further increased, and the expansion of cracks from the first reforming portion 21 can be easily promoted. The second virtual line VL2 is preferably located at a position shifted by 3 μm or more and 7 μm or less from the planned cutting line PC. By setting the amount of the second virtual line VL2 to be shifted from the planned cutting line PC in the plane direction of the substrate to 3 μm or more, the expansion of cracks from the first reforming section 21 can be efficiently promoted. By setting the amount of the second virtual line VL2 to be shifted from the planned cutting line PC in the plane direction of the substrate to 7 μm or less, the extension of the crack CR from the first reforming section 21 is promoted, and the third reforming section 23 It is possible to suppress the generation of cracks from.

Similarly, it is preferable that the first virtual line VL1 is also positioned at a position shifted by 3 μm or more and 7 μm or less from the planned cutting line PC. By setting the amount of shifting the first virtual line VL1 from the planned cutting line PC in the plane direction of the substrate to 3 μm or more, it is possible to efficiently promote the extension of cracks from the first reforming section 21. By setting the amount of the first virtual line VL1 to be shifted from the planned cutting line PC in the plane direction of the substrate to 7 μm or less, the extension of the crack CR from the first reforming section 21 is promoted, and the second reforming section 22 The occurrence of cracks can be suppressed.

It is preferable that the focusing position of the laser light in the third irradiation is about the same as the focusing position of the laser light in the first irradiation in the thickness direction of the substrate 50. As a result, the above-mentioned action of the third reforming section 23 to promote the extension of the crack CR from the first reforming section 21 can be effectively generated.
[Embodiment 3]

In the first and second embodiments, an example is described in which the irradiation condition of the laser beam LB is not changed for each scan but is constant, but the present invention is not limited to this configuration, and the irradiation condition of the laser beam is changed for each scan. May be good. As an example, a method of changing the pitch of the laser beam for each scan is shown in the plan view of FIG. 8A and the cross-sectional view of FIG. 8B as the third embodiment. Here, the pitch of the laser beam is the distance between adjacent focusing positions when the laser light is scanned and focused on a plurality of focusing positions. In the method shown in FIGS. 8A and 8B, first irradiation is performed by first scanning along the planned cutting line PC at the first pitch PH1, and then the second irradiation narrower than the first pitch PH1 is performed on the left and right sides of the planned cutting line PC. The second irradiation to irradiate with the pitch PH2 and the third irradiation to irradiate with the third pitch PH3 are performed. In other words, the first irradiation is performed by making the first pitch PH1 wider than the second pitch PH2 and the third pitch PH3. By scanning the laser beam under such irradiation conditions, the splittability of the substrate 50 can be improved. The reason why the splittability of the substrate 50 is improved is that the second reforming section 22 and the third reforming section 23 are formed more densely by narrowing the pitch, and the second reforming section 22 and the third reforming section are improved. It is presumed that this is because the force when the strain generated during the formation of the 23 is released is increased, and the extension of the crack CR from the first reforming portion 21 is further promoted. In the examples of FIGS. 8A and 8B, an example including the third irradiation was described, but even in the case of only the first irradiation and the second irradiation not including the third irradiation, the second pitch PH2 of the second irradiation is higher than that of the second irradiation. By widening the first pitch PH1 of the first irradiation, the splittability of the substrate 50 can be improved.

In the second and third embodiments, the amount of shifting the first virtual line VL1 in the plane direction of the substrate and the pitch when scanning the laser beam may be different between the second irradiation and the third irradiation.
[Examples 1 and 2; Comparative Examples 1 and 2]

In order to confirm the effectiveness of the present invention, the substrate 50 processed by changing the laser beam irradiation conditions in Examples 1 and 2 and Comparative Examples 1 and 2 was produced, and the results based on the respective laser beam irradiation conditions were obtained. evaluated. The irradiation conditions of the laser beam in Examples 1 and 2 and Comparative Examples 1 and 2 will be described.

As the substrate 50, a sapphire substrate having a thickness of 185 μm in which the semiconductor structure 11 was formed on the first main surface 51 was used. Then, Comparative Example 1 in which the scanning position of the laser beam in the thickness direction of the substrate 50 is the same for the first irradiation and the second irradiation, and Example 1 in which the scanning position of the laser beam is different between the first irradiation and the second irradiation. And, the substrate 50 was processed. Further, there is Comparative Example 2 in which the scanning position of the laser beam in the thickness direction of the substrate 50 is the same for the first irradiation, the second irradiation, and the third irradiation, and the scanning position of the laser beam is the first irradiation, the second irradiation, and the third irradiation. The substrate 50 was processed according to Example 2 which was different from each other by the third irradiation. In Example 1, the scanning position of the second irradiation was the same as that of the first irradiation in the thickness direction of the substrate 50, but was shifted by 3 μm from the scanning position of the first irradiation in the plane direction of the substrate 50. Further, in the second embodiment, the scanning positions of the second irradiation and the third irradiation are the same as those of the first irradiation in the thickness direction of the substrate 50, and the scanning positions of the first irradiation are set in the plane direction of the substrate 50, respectively. It was shifted by 3 μm. In Examples 1 and 2 and Comparative Examples 1 and 2, the irradiation conditions of the laser light other than the scanning position are set to be the same, the output of the laser light is 0.6 W, and the defocus amount is about 39 μm. The laser beam is pulse-driven and has a pitch of about 6 μm.

Then, the lengths of cracks generated in the substrate 50 in Comparative Examples 1 and 2 and Examples 1 and 2 were measured and compared. The measurement results of Examples 1 and 2 and Comparative Examples 1 and 2 are shown in FIG.

From the measurement results of FIG. 9, the scanning position of the laser beam in the thickness direction of the substrate 50 is shifted in the plane direction of the substrate 50 between the first irradiation and the second irradiation, as compared with the case where the scanning position of the laser beam is the same. It can be confirmed that the crack can be lengthened. That is, it was confirmed that the substrate 50 was easily cut. In Example 1 and Comparative Example 1 in which the laser beam was scanned twice, the crack could be extended by about 15 μm in Example 1 as compared with Comparative Example 1. Further, in Example 2 and Comparative Example 2 in which the laser beam was scanned three times, the crack could be extended by about 20 μm in Example 2 as compared with Comparative Example 2. In addition, from the comparison between Example 1 and Example 2, it was confirmed that the effect of extending the cracks was greater in the three scans than in the two scans. Further, in Comparative Examples 1 and 2, since the laser beam is irradiated to the same scanning position a plurality of times, a plurality of reformed portions 20 are formed more densely on the planned cutting line PC than in Examples 1 and 2. .. When the substrate 50 in such a state is cut along the planned cutting line PC, there is a tendency that a large force is required due to the cutting of the board 50. In Examples 1 and 2, since only the first reforming section 21 is provided on the planned cutting line PC, the force required for cutting the substrate 50 is smaller than that of Comparative Examples 1 and 2. According to the first embodiment, it is considered that the substrate 50 can be easily split because the expansion of cracks from the reforming portion 20 can be promoted without increasing the force required for splitting the substrate 50. Be done. Further, according to the second embodiment, since the expansion of cracks from the reforming portion 20 can be promoted as compared with the first embodiment, the substrate 50 can be more easily made without increasing the force required for breaking the substrate 50. It is thought that it can be divided.
[Examples 3 to 7; Comparative Example 3]

Further, the substrates 50 processed by changing the laser beam irradiation conditions in Examples 3 to 7 and Comparative Example 3 were produced, and the results under the respective laser beam irradiation conditions were evaluated. The irradiation conditions of the laser beam in Examples 3 to 7 and Comparative Example 3 will be described.

Similar to Examples 1 and 2 and Comparative Examples 1 and 2 described above, a sapphire substrate having a thickness of 185 μm in which the semiconductor structure 11 was formed on the first main surface 51 was used as the substrate 50. Then, the offset amounts d1 and d2, which are the amounts of the scanning positions of the second irradiation and the third irradiation shifted in the plane direction of the substrate 50 with respect to the scanning position of the first irradiation, are set in Examples 3 to 7 and Comparative Example 3, respectively. The test was conducted differently. The results are shown in FIGS. 10, 11A to 11F. In Examples 3 to 7 and Comparative Example 3, the offset amount d1 in the second irradiation and the offset amount d2 in the third irradiation were the same. Examples in which the offset amounts d1 and d2 are set to 0 μm are compared in Examples 3, examples in which the offset amounts are set to 1 μm in Examples 3, examples in which the offset amounts are set to 3 μm, Examples in Examples 4 and 5 μm, and Examples in which the offset amounts are set to 5 and 7 μm. An example of 6 and 10 μm was used as Example 7. Then, the crack length in the cross section of the substrate 50 was measured. Further, in Comparative Example 3, Example 4, and Example 6, the modified region by the laser beam in the plan view and the optical micrograph of the cross section of the substrate 50 were observed.

The irradiation conditions of the laser processing machine were set so that the output of the laser beam was 0.6 W, the defocus amount was 39 μm, and the feed rate was 600 mm / s. Laser irradiation was performed by scanning while driving the laser beam in a pulsed manner.

For each of Comparative Example 3, Example 4, and Example 6, FIGS. 11A to 11C show plan photographs of the modified region formed inside the substrate 50. 11D to 11F show cross-sectional photographs of the substrate 50. Of these, FIGS. 11A and 11D show Comparative Example 3, FIG. 11B, and FIG. 11E show Example 4, FIG. 11C, and FIG. 11F show Example 6, respectively.

FIG. 10 is a graph for confirming the change in the crack length by changing the offset amounts d1 and d2. Table 1 shows the conditions of the offset amounts d1 and d2 and the measurement results of the crack length in Comparative Example 3 and Examples 3 to 7, respectively. As shown in FIG. 10, in Examples 3 to 7 in which the offset amounts d1 and d2 are changed in the range of 1 μm or more and 10 μm or less, the offset amounts d1 and d2 are zero, that is, the cracks are not offset as compared with Comparative Example 3. The effect of extending the length was confirmed. Further, it was confirmed that by setting the offset amounts d1 and d2 to 3 μm or more and 7 μm or less, the cracks can be efficiently extended as compared with Comparative Example 3.

As shown in FIG. 11D, it can be seen that in Comparative Example 3, the length of the crack is short and does not reach the surface of the substrate 50. On the other hand, in Examples 4 and 6 shown in FIGS. 11E and 11F, it can be seen that the cracks extend to the surfaces of the substrate 50 (first main surface 51 and second main surface 52). From this, it was confirmed that the effect of promoting the extension of cracks can be obtained by setting the offset amounts d1 and d2 to 3 μm or more. On the other hand, in Example 6 shown in FIG. 11F, the crack is slightly meandering and extended, but in Example 4 shown in FIG. 11E, the crack is extended in a substantially linear shape. From this, it was confirmed that the meandering of cracks can be suppressed by setting the offset amounts d1 and d2 to 7 μm or less. From the above, it can be said that it is more preferable that the offset amount for shifting the irradiation position in the second and third irradiations from the irradiation position in the first irradiation in the plane direction is 3 μm or more and 7 μm or less.

Next, the pitch of the laser beam in the first irradiation, the second irradiation, and the third irradiation was changed, and the ease of extension of the crack from the first reforming section 21 by changing the pitch was examined. The laser light in the first irradiation was scanned along the planned cutting line PC, and the planned cutting line PC was set to be along the m-axis direction of the substrate 50 made of sapphire. The thickness of the substrate 50 is 150 μm. The scans in the second irradiation and the third irradiation were set at positions offset by 5 μm with respect to the first irradiation, respectively. The frequency of the laser beam was 75 kHz and the defocus was 20 μm. The pitch in the first irradiation was set to 4 μm, and the pitch in the second irradiation and the third irradiation was changed to 2 μm, 3 μm, and 4 μm. Then, for each condition, the pulse energy of the laser beam was changed to 1.8 μJ, 2 μJ, 2.2 μJ, and 2.4 μJ, and the ease of crack extension was examined. Under each condition, the pulse energy of the laser beam used for the first irradiation, the second irradiation, and the third irradiation was the same. Table 2 shows the results of verifying the elongation of cracks under each condition. The values indicated by [%] in Table 2 are values indicating how much the cracks were extended in the thickness direction of the substrate by observing the cross-sectional photograph of the substrate. For example, the condition of 100% means that the cracks have reached the first main surface 51 and the second main surface 52 of the substrate 50.

From the above results, it can be seen that the pulse energy required for crack extension increases as the pitch in the second irradiation and the third irradiation is widened. From this, it can be seen that by making the pitch of the laser light in the second irradiation and the third irradiation narrower than the pitch of the laser light in the first irradiation, the crack can be sufficiently extended with a smaller pulse energy. By reducing the pulse energy required for crack extension, damage to the semiconductor layer due to laser irradiation can be reduced.
[Embodiment 4]

Whether the first virtual line VL1 that scans the laser beam in the second irradiation is set to the left or right side with respect to the scheduled cut line PC depends on the orientation flat surface OF in the plan view of the substrate 50 made of sapphire and the cut schedule. It depends on the positional relationship with the line PC. For example, as shown in FIG. 12, the planned cutting line PC is set in the m-axis direction parallel to the orientation flat surface OF (plane A) in a plan view with the orientation flat surface OF of the substrate 50 placed on the front side. Consider the case where the substrate 50 is cut. Here, in the following description, for convenience, the front side when the orientation flat surface OF of the substrate 50 is arranged on the front side is set as the bottom, and the top and bottom and the left and right sides are defined with respect to the substrate 50 with the bottom as a reference. Even when the substrate 50 is rotated and the position of the orientation flat surface OF is changed, the up / down and left / right specified before the substrate 50 is rotated are applied. In FIG. 12, the orientation flat surface OF when the orientation flat surface OF is arranged on the front side is horizontal, and the angle of the orientation flat surface OF in the plan view is 0 ° in the sense that it coincides with the horizontal plane.

FIG. 13 is a schematic plan view in which a plurality of reforming portions 20 are formed on the substrate 50 by laser irradiation. In FIG. 13, the first pass is set as the planned cut line PC, and the first virtual line VL1 of the second pass is set to the first virtual line VL1 + which is the + direction on the upper side, or the first virtual line which is the minus direction on the lower side. Whether to set the line VL1- is examined based on the difference in meandering on the surface of the substrate 50 caused by the extension of cracks.

This will be described with reference to the perspective views of FIGS. 14A and 14B. FIG. 14A is an example in which the first virtual line VL1 +, which is the second pass, is set on the left side with respect to the planned cutting line PC. Further, FIG. 14B is an example in which the first virtual line VL1-, which is the second pass, is set on the right side with respect to the planned cutting line PC. In either case, the extension directions of the cracks generated by the second irradiation from the second pass to the first pass are almost the same, so that the degree of meandering does not change. An example of a micrograph of the surface of the substrate 50 in a plan view is shown in FIG. 15A, an example in which the first virtual line VL1 on the second pass is offset by +5 μm from the planned cutting line PC, and an example in which the first virtual line VL1 is offset by -5 μm is shown in FIG. 15B. Each is shown. As shown in these figures, when the substrate 50 is divided in the m-axis direction, the degree of meandering on the surface of the substrate 50 is almost the same regardless of which direction the first virtual line VL1 is displaced from the planned division line PC. It didn't change.

The example of cutting the substrate 50 in the m-axis direction has been described above. Next, an example of dividing the substrate 50 in the a-axis direction will be described with reference to FIGS. 16A, 16B, 17A to 17D, 18A, and 18B. FIG. 16A shows a schematic perspective view of an example in which the first virtual line VL1 which is the second pass is offset in the + direction on the left side from the first pass. FIG. 16B shows a schematic perspective view of an example in which the first virtual line VL1 which is the second pass is offset in the minus direction on the right side from the first pass. Further, FIGS. 17A and 17B show micrographs in a plan view of an example in which the second pass is offset by 5 μm in the + direction from the first pass, respectively. 17C and 17D show photomicrographs of an example in which the second pass is offset by 5 μm in the minus direction from the first pass, respectively. Further, FIG. 18A shows a schematic cross-sectional view of the substrate 50 of FIG. 16A, and FIG. 18B shows a schematic cross-sectional view of the substrate 50 of FIG. 16B.

When the substrate 50 is divided in the m-axis direction, the substrate 50 is divided in a direction substantially perpendicular to the thickness direction of the substrate 50. Therefore, it is considered that the degree of meandering on the surface of the substrate 50 was substantially the same regardless of whether the first virtual line VL1 was on the upper side or the lower side of the planned cutting line PC. On the other hand, when the substrate 50 is cut in the a-axis direction, the substrate 50 tends to be cut diagonally with respect to the thickness direction of the substrate 50 due to the influence of the crystal plane of sapphire. Therefore, when the second reforming section 22 is formed by offsetting the first virtual line VL1 which is the second pass in the + direction as in the comparative example shown in FIG. 16A, the first pass is as shown in FIG. 18A. Due to the cracks formed from the first reforming section 21, the cracks from the second reforming section 22 may be connected to the cracks from the first reforming section 21. In such a case, in the comparative examples shown in FIGS. 17A and 17B, meandering of cracks occurs on the surface of the substrate 50. For example, in FIGS. 17A and 17B, the portion where the crack is formed in a curved shape instead of a linear portion is a meandering portion on the lower side.

On the other hand, as shown in FIGS. 16B and 18B for explaining the fourth embodiment, when the first virtual line VL1 which is the second pass is offset in the minus direction to form the second reforming section 22, one pass is formed. The influence of the crack extending diagonally from the first reforming portion 21 formed by the eye on the crack from the second reforming portion 22 is reduced. For example, as shown in FIG. 18B, when the crack from the first reforming portion 21 extends toward the second main surface 52 side of the substrate 50, it passes over the region where the second reforming portion 22 is formed. Extend without. As a result, as described above, the cracks from the second reforming section 22 are suppressed from being connected to the cracks from the first reforming section 21, so that the meandering of the cracks on the surface of the substrate 50 can be suppressed. .. As a result, as shown in FIGS. 17C and 17D, meandering of cracks on the surface of the substrate 50 is suppressed. From the above, with the orientation flat surface OF placed on the front side, the first irradiation is performed on the planned cutting line PC set in the direction (a axis) perpendicular to the orientation flat surface OF (A surface). .. After that, it is preferable to set the first virtual line VL1 in a direction perpendicular to the orientation flat surface OF on the right side of the planned cutting line PC and perform the second irradiation. As a result, it is possible to suppress a situation in which cracks on the surface of the substrate 50 meander when the substrate 50 is cut.
[Embodiment 5]

In the fourth embodiment, as shown in FIG. 12, it is preferable to divide the substrate 50 in the m-axis direction and the a-axis direction in a posture where the angle formed by the orientation flat surface OF and the horizontal plane is 0 °. The setting of the first virtual line VL1 was examined. In the fifth embodiment, as shown in FIG. 19, it is preferable to divide the substrate 50 in the vertical direction and the horizontal direction in a state where the substrate 50 is placed in a posture where the angle between the orientation flat surface OF and the horizontal plane is 45 °. Consider the setting of the first virtual line VL1.

As shown in FIG. 19, a plane schematically showing a plurality of reforming portions 20 formed by scanning a laser beam in the left-right direction with the substrate 50 tilted 45 ° with respect to the horizontal plane of the orientation flat surface OF. The figures are shown in FIGS. 20A and 20C. FIG. 20A shows a state in which the pulse-driven laser beam is scanned in the direction of traveling from the left side to the right side indicated by the arrow in the figure. FIG. 20C shows a state in which the pulse-driven laser beam is scanned in the direction of traveling from the right side to the left side indicated by the arrow in the figure. 20B is a photomicrograph of the scanned substrate shown in FIG. 20A, and FIG. 20D is a photomicrograph of the scanned substrate shown in FIG. 20C. As shown in these figures, when the laser beam is scanned, among the plurality of cracks extending from the reforming portion 20, the cracks formed on the opposite side of the traveling direction of the laser beam, and the crack closest to the scanning line is formed. It turns out that it tends to be stretched the most. In FIG. 20A, the length of the most extending crack among the plurality of cracks (straight lines) extending from the modified portion 20 is shown to be longer than the other cracks. It is presumed that such a tendency is due to the fact that the laser beam is not scanned along the m-axis direction or the a-axis direction of the substrate 50. Therefore, after forming the first reforming section 21 along the planned cutting line PC, the position of the first virtual line VL1 and the scanning direction of the laser beam are determined in consideration of the extension of cracks from the first reforming section 21. It is preferable to perform the set second irradiation.

In the schematic plan view of FIG. 21A, the laser beam was scanned from the right side to the left side along the planned cut line PC in the first pass, and then offset upward with respect to the planned cut line PC in the second pass. The extension of the crack when the laser beam is scanned from the left side to the right side along the first virtual line VL1 is shown. When scanning the laser beam as shown in FIG. 21A, among the cracks from the second reforming portion 22 formed in the second pass, the cracks extending longer than the other cracks were formed in the first pass. It is formed in close proximity to a crack extending longer than the other cracks among the cracks from the modified portion 21. Therefore, the cracks from the first reforming section 21 and the second reforming section 22 are connected to each other, and the cracks formed on the surface of the substrate 50 tend to meander.

Next, in the schematic plan view of FIG. 21B, the laser beam is scanned from the right side to the left side along the planned cut line PC in the first pass, and then offset to the lower side of the planned cut line PC in the second pass. The extension of the crack when the laser beam is scanned from the left side to the right side along the first virtual line VL1 is shown. When scanning the laser beam as shown in FIG. 21B, the extension direction of the cracks from the second reforming portion 22 formed in the second pass, which is longer than the other cracks, was formed in the first pass. Among the cracks from the first reforming portion 21, the direction is opposite to the extension direction of the crack longer than the other cracks. In FIG. 20C, the length of the most extending crack among the plurality of cracks (straight lines) extending from the modified portion 20 is shown to be longer than the other cracks. Therefore, among the cracks from the first reforming section 21 and the second reforming section 22, it becomes difficult to connect the cracks longer than the other cracks. By suppressing the connection between such cracks, it is possible to prevent the cracks formed on the surface of the substrate 50 from meandering.

From the above, in the substrate 50 in the posture in which the orientation flat surface OF is arranged on the front side and the posture is rotated by 45 ° counterclockwise, the laser is first referred to the planned split line PC set in the left-right direction. The first irradiation is performed by scanning the light from the right side to the left side in the first traveling direction. After that, it is preferable to set the first virtual line VL1 below the planned cutting line PC and perform the second irradiation to scan the laser beam in the second traveling direction from the left side to the right side.

Further, although the case where the substrate 50 is cut along the left-right direction has been described above, when the substrate 50 is cut along the vertical direction, the second irradiation is similarly performed in consideration of the crack from the first reforming portion 21. Is preferable. That is, in the substrate 50 in the posture in which the orientation flat surface OF of the substrate 50 is placed on the front side and rotated by 45 ° counterclockwise, the laser is first referred to the planned split line PC set in the vertical direction. The first irradiation is performed by scanning the light from the lower side to the upper side in the first traveling direction. After that, the first virtual line VL1 is set on the right side of the planned cutting line PC, and the second irradiation is performed so that the laser beam is scanned in the second traveling direction from the upper side to the lower side. By doing so, similarly to the above, the connection between the cracks extending from the modified portions formed in the first pass and the second pass is suppressed, and the cracks formed on the surface of the substrate 50 meander. It can be suppressed.

Further, in the above example, the case where the first traveling direction of the first pass is from the right side to the left side has been described, but the first traveling direction may be the direction from the left side to the right side. In this case, the second irradiation may be performed by setting the first virtual line VL1 above the planned cutting line PC and setting the laser beam in the second traveling direction from the right side to the left side. Furthermore, in the above example, the case where the first traveling direction of the first pass is the direction from the lower side to the upper side has been described, but the first traveling direction may be the direction from the upper side to the lower side. In this case, the second irradiation may be performed by setting the first virtual line VL1 on the left side of the planned cutting line PC and setting the laser beam in the second traveling direction from the lower side to the upper side. Even in such a case, as in the above case, the connection between the cracks extending from the modified portions formed in the first pass and the second pass is suppressed, and the cracks formed on the surface of the substrate 50 meander. It can be suppressed.

3 ... Electrode 3A ... n-side pad electrode 3B ... p-side pad electrode 6 ... n-type semiconductor layer 7 ... p-type semiconductor layer 8 ... active region 10, 10B ... light emitting element 11 ... semiconductor structure 13 ... translucent conductive layer 14 ... Protective film 18 ... Light extraction surface 20 ... Modification section 21 ... First modification section 22 ... Second modification section 23 ... Third modification section 26 ... Modification line 50 ... Substrate 51 ... First main surface 52 ... First Two main surface LB ... Laser light CR ... Crack OF ... Orientation flat surface PC, PC'... Scheduled split line PH1 ... First pitch PH2 ... Second pitch PH3 ... Third pitch VL1, VL1 +, VL1- ... First virtual line VL2 ... Second virtual line d1 ... Offset amount in the second irradiation d2 ... Offset amount in the third irradiation

Claims (14)

A method for manufacturing a light emitting element, which condenses laser light inside a substrate on which a semiconductor structure is formed to form a plurality of modified portions, and then cuts the substrate.
The laser beam is scanned along a preset planned cutting line to form a plurality of first reforming portions located on the planned cutting line and cracks generated from the first reforming portion inside the substrate. The process of performing the first irradiation and
After the first irradiation, the laser beam is scanned along the first virtual line parallel to the planned cut line in the top view and shifted by a predetermined amount in the plane direction of the substrate, and the first virtual line is inside the substrate. A step of performing a second irradiation that promotes the extension of the crack generated from the first reforming portion by forming a plurality of second reforming portions located on the line, and a step of performing the second irradiation.
A step of cutting the substrate starting from a plurality of the first reforming portions, and
A method for manufacturing a light emitting device including. The method for manufacturing a light emitting element according to claim 1.
A method for manufacturing a light emitting element, wherein the output of the laser beam in the second irradiation is equal to or higher than the output of the laser beam in the first irradiation. The method for manufacturing a light emitting element according to claim 1 or 2.
The first virtual line is a method for manufacturing a light emitting element having a position shifted from the planned cutting line by 3 μm or more and 7 μm or less. The method for manufacturing a light emitting device according to any one of claims 1 to 3.
A method for manufacturing a light emitting element in which the focusing position of the laser light in the second irradiation is the same as the focusing position of the laser light in the first irradiation in the thickness direction of the substrate. The method for manufacturing a light emitting element according to any one of claims 1 to 4.
A method for manufacturing a light emitting element in which the pitch of the laser beam in the second irradiation is narrower than the pitch of the laser beam in the first irradiation. The method for manufacturing a light emitting device according to any one of claims 1 to 5.
The substrate is a method for manufacturing a light emitting element made of sapphire. The method for manufacturing a light emitting element according to claim 6.
The substrate has a substantially circular shape in a plan view, and has an orientation flat surface parallel to the A surface of the substrate at a part of the peripheral edge thereof.
In a plan view, when the front side is the bottom when the orientation flat surface is arranged on the front side, and the top, bottom, left and right are defined with respect to the substrate with the bottom as a reference.
The first advance of the laser beam from the right side to the left side with respect to the planned split line set in the left-right direction in the posture in which the orientation flat surface is arranged on the front side and rotated by 45 ° counterclockwise. After scanning in the direction and performing the first irradiation,
A method for manufacturing a light emitting element that performs the second irradiation by setting the first virtual line below the planned cutting line and scanning the laser beam in the second traveling direction from the left side to the right side. The method for manufacturing a light emitting element according to claim 6.
The substrate has a substantially circular shape in a plan view, and has an orientation flat surface parallel to the A surface of the substrate at a part of the peripheral edge thereof.
In a plan view, when the front side is the bottom when the orientation flat surface is arranged on the front side, and the top, bottom, left and right are defined with respect to the substrate with the bottom as a reference.
The first direction in which the laser beam is directed from the lower side to the upper side with respect to the planned division line set in the vertical direction in a posture in which the orientation flat surface is arranged on the front side and rotated by 45 ° counterclockwise. After scanning in the traveling direction and performing the first irradiation,
A method for manufacturing a light emitting element that performs the second irradiation by setting the first virtual line on the right side of the planned cutting line and scanning the laser beam in the second traveling direction from the upper side to the lower side. The method for manufacturing a light emitting element according to claim 6.
The substrate has a substantially circular shape in a plan view, and has an orientation flat surface parallel to the A surface of the substrate at a part of the peripheral edge thereof.
In a plan view, when the front side is the bottom when the orientation flat surface is arranged on the front side, and the top, bottom, left and right are defined with respect to the substrate with the bottom as a reference.
With the orientation flat surface arranged on the front side, the first irradiation is performed on the planned split line set in the direction perpendicular to the orientation flat surface, and then the first virtual line is scheduled to be split. A method for manufacturing a light emitting element that is set in a direction perpendicular to the orientation flat surface on the right side of the line and performs the second irradiation. The method for manufacturing a light emitting device according to any one of claims 1 to 9, further comprising:
After the second irradiation and before the step of cutting the substrate, the substrate is displaced by a predetermined amount in the plane direction of the substrate on the side opposite to the first virtual line in the top view. (Ii) A method for manufacturing a light emitting element, comprising a step of scanning a laser beam along a virtual line and performing a third irradiation to form a plurality of third modified portions located on the second virtual line inside the substrate. The method for manufacturing a light emitting element according to claim 10.
A method for manufacturing a light emitting element, wherein the output of the laser beam in the third irradiation is equal to or higher than the output of the laser beam in the first irradiation. The method for manufacturing a light emitting element according to claim 10 or 11.
The second virtual line is a method for manufacturing a light emitting element having a position shifted from the planned cutting line by 3 μm or more and 7 μm or less. The method for manufacturing a light emitting device according to any one of claims 10 to 12.
A method for manufacturing a light emitting element in which the focusing position of the laser light in the third irradiation is the same as the focusing position of the laser light in the first irradiation in the thickness direction of the substrate. The method for manufacturing a light emitting device according to any one of claims 1 to 13.
A method for manufacturing a light emitting element having a substrate thickness of 100 μm or more and 300 μm or less.

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