JP6656597B2 - Light emitting device manufacturing method - Google Patents

Description

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

  As a method for manufacturing a light-emitting element in which a compound semiconductor serving as a light-emitting layer is stacked on a substrate, a method of forming an element separation line by irradiating the substrate with a laser has been proposed. In a method for manufacturing a light emitting element, improvement in productivity is required.

Japanese Patent No. 5119463

  The present invention provides a method for manufacturing a light emitting device that can improve productivity.

  According to one embodiment of the present invention, a method for manufacturing a light-emitting element includes applying a laser beam to a substrate of a wafer including a substrate having a first surface and a second surface, and a semiconductor structure provided on the second surface. Irradiating a laser beam to form a plurality of modified regions inside the substrate; and separating the wafer into a plurality of light emitting elements after the laser beam irradiating process. The laser light irradiation step includes a first irradiation step of scanning the laser light along a plurality of first lines. The plurality of first lines extend in a first direction parallel to the first surface, and are arranged in a second direction parallel to the first surface and intersecting the first direction. The laser light irradiation step includes a second irradiation step of scanning the laser light along a second line extending in the second direction after the first irradiation step. In the first irradiation step, the laser light is applied to a plurality of positions along the first direction, and a first irradiation pitch of the plurality of positions along the first direction is 2.5 μm or less, The pitch of the plurality of first lines in the second direction is 0.7 mm or more.

  According to one embodiment of the present invention, a method for manufacturing a light-emitting element which can improve productivity is provided.

4 is a flowchart illustrating a method for manufacturing a light emitting device according to an embodiment. FIG. 3 is a schematic view illustrating a wafer used in the method for manufacturing a light emitting device according to the embodiment. FIG. 3 is a schematic view illustrating a wafer used in the method for manufacturing a light emitting device according to the embodiment. It is a schematic diagram which illustrates a part of the manufacturing method of the light emitting element which concerns on embodiment. It is a schematic plan view which illustrates a part of the manufacturing method of the light emitting element concerning an embodiment. It is a schematic plan view which illustrates a part of the manufacturing method of the light emitting element concerning an embodiment. It is a schematic plan view which illustrates a part of the manufacturing method of the light emitting element concerning an embodiment. It is a schematic plan view which illustrates a part of the manufacturing method of the light emitting element concerning an embodiment. It is a schematic cross section which illustrates a part of manufacturing method of a light emitting element. FIG. 9 is a graph illustrating an experimental result regarding a method for manufacturing a light emitting device. 7 is a micrograph image illustrating an experimental result regarding a method for manufacturing a light emitting device. 7 is a micrograph image illustrating an experimental result regarding a method for manufacturing a light emitting device. It is a schematic diagram which illustrates the experimental result regarding the manufacturing method of a light emitting element. It is a schematic diagram which illustrates a part of another manufacturing method of the light emitting element which concerns on embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The drawings are schematic or conceptual, and the relationship between the thickness and the width of each part, the size ratio between the parts, and the like are not necessarily the same as actual ones. In addition, even when the same part is represented, the dimensions and ratios may be represented differently depending on the drawings.
In the specification of the present application, the same reference numerals are given to the same elements as those described above with respect to the already-described drawings, and the detailed description will be appropriately omitted.

FIG. 1 is a flowchart illustrating a method for manufacturing a light emitting device according to the embodiment.
2 and 3 are schematic views illustrating a wafer used in the method for manufacturing a light emitting device according to the embodiment. FIG. 2 is a sectional view taken along line II-II of FIG. FIG. 3 is a plan view seen from the arrow AR of FIG.

  As shown in FIG. 1, the method for manufacturing a light emitting device according to the embodiment includes a laser light irradiation step (Step S110) and a separation step (Step S120). The laser beam irradiation step includes a first irradiation step (Step S111) and a second irradiation step (Step S112). The separation step includes a first separation step (Step S121) and a second separation step (Step S122).

  In the laser irradiation step, the wafer is irradiated with laser light. Hereinafter, an example of a wafer will be described.

  As shown in FIGS. 2 and 3, the wafer 50W includes a substrate 50 and a semiconductor structure 51. The substrate 50 has a first surface 50a and a second surface 50b. The second surface 50b is a surface opposite to the first surface 50a. The semiconductor structure 51 is provided on the second surface 50b, for example.

The semiconductor structure 51 includes, for example, an n-type semiconductor layer, an active layer, and a p-type semiconductor layer. An n-type semiconductor layer is located between the p-type semiconductor layer and the substrate 50. An active layer is located between the p-type semiconductor layer and the n-type semiconductor layer. The semiconductor structure 51 includes, for _{example, In x Al y Ga 1-x} -y N (0 ≦ x, 0 ≦ y, x + y <1) nitride such as semiconductor. The peak wavelength of the light emitted from the active layer is, for example, 360 nm or more and 650 nm or less.

  The direction from the second surface 50b toward the first surface 50a is defined as a Z-axis direction. One direction perpendicular to the Z-axis direction is defined as an X-axis direction. A direction perpendicular to the Z-axis direction and the X-axis direction is defined as a Y-axis direction. The first surface 50a and the second surface 50b extend along the XY plane. The Z-axis direction corresponds to a thickness direction (for example, a depth direction) of the substrate 50.

  As shown in FIG. 3, the semiconductor structure 51 includes, for example, a plurality of regions 51r. Each of the plurality of regions 51r corresponds to one light emitting element. The plurality of regions 51r are arranged in the first direction D1 and the second direction D2.

  The first direction D1 is one direction parallel to the first surface 50a. The second direction D2 is parallel to the first surface 50a and crosses the first direction D1. The second direction D2 is, for example, perpendicular to the first direction D1. In this example, the first direction D1 is along the X-axis direction. The second direction D2 runs along the Y-axis direction.

  The substrate 50 is made of, for example, sapphire. The substrate 50 is, for example, a sapphire substrate (for example, a c-plane sapphire substrate). In the substrate 50, the first surface 50a may be inclined with respect to the c-plane. When the substrate 50 is a sapphire substrate, in one example, the first direction D1 is along the m-axis of the sapphire substrate. At this time, the second direction D2 is along the a-axis of the sapphire substrate.

  The substrate 50 has an orientation flat 55. In this example, the direction in which the orientation flat 55 extends is along the first direction D1 of the wafer 50W. In the embodiment, the relationship between the first direction D1 and the direction in which the orientation flat 55 extends is arbitrary. The relationship between the second direction D2 and the direction in which the orientation flat 55 extends is arbitrary.

  Laser light is irradiated on such a wafer 50W. The wafer 50W is separated along the boundaries of the plurality of regions 51r. A plurality of light emitting elements can be obtained from the plurality of regions 51r.

FIG. 4 is a schematic view illustrating a part of the method for manufacturing the light emitting device according to the embodiment.
FIG. 4 exemplifies laser beam irradiation. As shown in FIG. 4, the substrate 50 of the wafer 50W is irradiated with a laser beam 61. In this example, the laser light 61 enters the substrate 50 from the first surface 50a.

  The laser light 61 is emitted in a pulse shape. As the laser light source, for example, an Nd: YAG laser, a titanium sapphire laser, an Nd: YVO4 laser, an Nd: YLF laser, or the like is used. The wavelength of the laser light 61 is the wavelength of light transmitted through the substrate 50. The laser beam 61 is, for example, a laser beam having a peak wavelength in a range from 800 nm to 1200 nm.

  The laser beam 61 is scanned along a direction parallel to the XY plane. For example, the relative position between the laser beam 61 and the substrate 50 is changed along a direction parallel to the XY plane. The position of the focal point of the laser beam 61 along the Z-axis direction (position based on the substrate 50) may be changeable.

  For example, the laser beam 61 is discretely applied along one direction along the first surface 50a of the substrate 50. The plurality of positions irradiated with the laser beam 61 are separated from each other along one direction. The plurality of positions irradiated with the laser beam 61 are arranged at one pitch (laser irradiation pitch Lp). The laser irradiation pitch Lp corresponds to a pitch between shots of the laser beam 61.

  The irradiation of the laser beam 61 forms a plurality of modified regions 53 inside the substrate 50. The laser light 61 is focused inside the substrate 50. At a position at a specific depth inside the substrate 50, energy due to the laser beam 61 concentrates. Thus, a plurality of modified regions 53 are formed. The pitch of the converging point of the laser beam 61 when forming the plurality of modified regions 53 corresponds to the laser irradiation pitch Lp. The modified region 53 is, for example, a region that is embrittled by laser irradiation inside the substrate 50.

  From the plurality of modified regions 53, for example, cracks propagate. The crack extends in the Z-axis direction of the substrate 50. The crack becomes a starting position of the separation of the substrate 50. For example, in a separation step described later, a force (for example, a load or an impact) is applied. Thereby, the substrate 50 is separated based on the crack.

  As described above, in the laser light irradiation step (Step S110), the substrate 50 is irradiated with the laser light 61 to form a plurality of modified regions 53 inside the substrate 50. Laser irradiation is performed, for example, along the first direction D1 and the second direction D2.

  Then, in the separation step (step S120), after the laser light irradiation step, the wafer 50W is separated into a plurality of light emitting elements. For example, by performing separation along two directions, the wafer 50W is separated into a plurality of light emitting elements.

Hereinafter, an example of the laser beam irradiation step will be described.
FIG. 5 is a schematic plan view illustrating a part of the method for manufacturing the light emitting device according to the embodiment.
FIG. 5 illustrates the first irradiation step (Step S111). As shown in FIG. 5, in the first irradiation step, the laser beam 61 is scanned along a plurality of first lines L1.

  The plurality of first lines L1 extend in the first direction D1 and are arranged in the second direction D2. As described above, the first direction D1 is parallel to the first surface 50a. The second direction D2 is parallel to the first surface 50a and crosses the first direction D1. The plurality of first lines L1 are arranged at a first pitch P1. The first pitch P1 is a distance between two adjacent first lines L1 in the second direction D2 along the second direction D2. In the embodiment, the first pitch P1 is, for example, 0.7 mm or more. The first pitch P1 is preferably 0.7 mm or more and 3 mm or less, more preferably 0.9 mm or more and 2.5 mm or less, and still more preferably 1 mm or more and 2 mm or less.

  The plurality of first lines L1 are along a boundary between a plurality of regions 51r (see FIG. 3) arranged in the second direction D2, for example.

  As shown in FIG. 5, in the irradiation of the laser beam 61 along one of the plurality of first lines L1, the laser beam 61 is applied to the plurality of first positions 61a. The plurality of first positions 61a are arranged along the first direction D1. The pitch of the plurality of first positions 61a corresponds to the first irradiation pitch Lp1. In the first irradiation pitch Lp1, two first positions 61a adjacent in the first direction D1 are along the first direction D1.

  The first irradiation pitch Lp1 is, for example, 2.5 μm or less, preferably 2.0 μm or less, and more preferably 1.5 μm or less.

FIG. 6 is a schematic plan view illustrating a part of the method for manufacturing the light emitting device according to the embodiment.
FIG. 6 illustrates the second irradiation step (Step S112). As shown in FIG. 6, in the second irradiation step, the laser beam 61 is scanned along a plurality of second lines L2.

  The multiple second lines L2 extend in the second direction D2. The plurality of second lines L2 are arranged at a second pitch P2 in the first direction D1. The second pitch P2 is a distance between two adjacent second lines L2 in the first direction D1 along the first direction D1.

  The plurality of second lines L2 are along a boundary between the plurality of regions 51r (see FIG. 3) arranged in the first direction D1, for example.

  In the irradiation of the laser light 61 along one of the plurality of second lines L2 in the second irradiation step, the laser light 61 is applied to the plurality of second positions 61b. The plurality of second positions 61b are arranged along the second direction D2. The pitch of the plurality of second positions 61b corresponds to the second irradiation pitch Lp2. In the second irradiation pitch Lp2, two second positions 61b adjacent in the second direction D2 are along the second direction D2.

  In one example, the first irradiation pitch Lp1 is smaller than the second irradiation pitch Lp2.

  In one example, the first pitch P1 (see FIG. 5) is smaller than the second pitch P2 (see FIG. 6). The first pitch P1 may be larger than the second pitch P2, or the first pitch P1 and the second pitch P2 may be the same.

Hereinafter, an example of the separation step will be described.
FIG. 7 is a schematic plan view illustrating a part of the method for manufacturing the light emitting device according to the embodiment.
FIG. 7 illustrates the first separation step. In the first separation step, the wafer 50W is separated into the plurality of bars 52 along the plurality of first lines L1. For example, by applying a load to the wafer 50W along the first line L1 using a blade, the wafer 50W is separated into the plurality of bars 52. In the embodiment, one bar 52 is in a state where a plurality of regions 51r are arranged in the first direction D1.

FIG. 8 is a schematic plan view illustrating a part of the method for manufacturing the light emitting device according to the embodiment.
FIG. 8 illustrates the second separation step. The second separation step is performed after the first separation step. In the second separation step, after the first separation step, the bar 52 is separated into the plurality of light emitting elements 51e along the plurality of second lines L2. For example, by applying a load to the bar 52 (wafer 50W) along the second direction D2 using a blade, the bar 52 is separated into a plurality of light emitting elements 51e.

  The above separation is performed, for example, by cleaving.

  As described above, in one example, the first pitch P1 is smaller than the second pitch P2. In one of the plurality of light emitting elements 51e obtained by the above manufacturing method, the length along the first direction D1 is longer than the length along the second direction D2. One of the plurality of light emitting elements 51e has a long side and a short side. The length of the long side substantially corresponds to the second pitch P2. The length of the short side corresponds to the first pitch P1.

  As described above, in the laser light irradiation step, the first irradiation step (Step S111) and the second irradiation step (Step S112) are performed. It has been found that when the second irradiation step is performed after the first irradiation step, the substrate 50 (wafer 50W) may be irradiated with the laser beam 61 in an undesired state. Hereinafter, this example will be described.

FIG. 9 is a schematic cross-sectional view illustrating a part of the method for manufacturing a light emitting device.
FIG. 9 illustrates the state of irradiation of the substrate 50 and the laser beam 61 when the second irradiation step is performed after the first irradiation step. In this example, the first irradiation step is not performed under appropriate conditions.

  As shown in FIG. 9, in a first irradiation step, a laser beam 61 is irradiated along a first line L1. Thus, a plurality of modified regions 53a are formed inside the substrate 50. FIG. 9 illustrates a cross section by a plane including the second direction D2 and the Z-axis direction. Therefore, one of the plurality of modified regions 53a is illustrated. The plurality of modified regions 53a are arranged along the first direction D1.

  When the irradiation conditions of the laser beam 61 are appropriate, a plurality of modified regions 53a are formed in the substrate 50, and a crack CR occurs in the substrate 50. However, the main surface (for example, the first surface 50a) of the substrate 50 It is continuous and one plane. That is, the substrate 50 is not separated from the crack CR only by irradiating the laser beam 61. The crack CR is generated from the plurality of modified regions 53 as starting points.

  On the other hand, if the irradiation conditions of the laser beam 61 are inappropriate, a plurality of modified regions 53a are formed on the substrate 50, and a crack CR occurs on the substrate 50. Due to the crack CR, the first surface 50a of the substrate 50 is separated at the first line L1 as a boundary. The two first surfaces 50a formed separately are not continuous. The two first surfaces 50a are inclined with respect to each other. As described above, when the irradiation conditions of the laser beam 61 are inappropriate, an unintended “crack” occurs in the substrate 50.

  Due to this unintended “cracking”, the first surface 50a of the substrate 50 is not flat. Due to the “crack”, the first surface 50a is inclined. When the second irradiation step is performed in this state, the depth position of the focal point of the laser beam 61 in the substrate 50 is not constant. Therefore, the depth positions of the plurality of modified regions 53b formed in the second irradiation step are not constant.

  As shown in FIG. 9, for example, in a region near the crack CR, the position of the modified region 53b is deep. On the other hand, in a region far from the crack CR, the position of the modified region 53b is shallow. For this reason, it becomes difficult to perform the separation based on the second irradiation step (second separation step) in a desired state. For example, a defect is likely to occur and a yield is likely to decrease, so that it becomes difficult to sufficiently increase productivity. In a region near the crack CR, the position where the laser beam 61 is converged is closer to the semiconductor structure 51. For this reason, damage by the laser beam 61 occurs in the semiconductor structure 51.

  Thus, it was found that if the conditions of the first irradiation step were inappropriate, unintended “cracks” occurred, and as a result, it was difficult to perform the second irradiation step under appropriate conditions.

  In the embodiment, the conditions of the first irradiation step are set to be appropriate. Thereby, for example, unintended “cracking” can be suppressed. Thereby, the second irradiation step can be performed under appropriate conditions. A method for manufacturing a light-emitting element that can improve productivity can be provided.

  Hereinafter, experimental results regarding the conditions of the first irradiation step will be described.

  In the experiment, a sapphire substrate having a thickness of 200 μm was used as the substrate 50. The planar shape of the sample is a square with a side length of 10.2 mm. The central portion of the sample was irradiated with laser light 61 with different irradiation conditions. Laser light 61 was applied along the m-axis of the sapphire substrate. After the irradiation with the laser beam 61, the breaking strength of the sample was measured. In the measurement of the breaking strength, the pushing speed of the head applied to the sample is 0.05 mm / sec.

In the sample SP11, the power of the laser beam 61 is 3.5 μJ, and the laser irradiation pitch Lp is 1.5 μm. In the sample SP11, the laser pulse width is 5.0 ps.
In the sample SP12, the power of the laser beam 61 is 3.5 μJ, and the laser irradiation pitch Lp is 2.0 μm. In the sample SP12, the laser pulse width is 5.0 ps.
In the sample SP13, the power of the laser beam 61 is 3.5 μJ, and the laser irradiation pitch Lp is 2.5 μm. In the sample SP13, the laser pulse width is 5.0 ps.
In the sample SP14, the power of the laser beam 61 is 3.5 μJ, and the laser irradiation pitch Lp is 3.0 μm. In the sample SP14, the laser pulse width is 5.0 ps.
Thus, in the samples SP11 to SP14, of the irradiation conditions of the laser beam 61, the power and the laser pulse width have the same value, and the value of the laser irradiation pitch is changed.

FIG. 10 is a graph illustrating an experimental result on a method for manufacturing a light emitting device.
The vertical axis in FIG. 10 is the breaking strength N1 (Newton: N). FIG. 10 shows the breaking strength N1 of the samples SP11 to SP14. The breaking strength N1 of each of the samples SP11 to SP14 shown in FIG. 10 is an average of the values obtained by performing three measurements on each of the samples SP11 to SP14. The breaking strength N1 of the sample SP11 was 3.8N. The breaking strength N1 of the sample SP12 was 2.3N. The breaking strength N1 of the sample SP13 was 1.6N. The breaking strength N1 of the sample SP14 was 0.6N.

  As can be seen from FIG. 10, the breaking strength N1 strongly depends on the laser irradiation pitch Lp. By reducing the laser irradiation pitch Lp, a high breaking strength N1 can be obtained. In the above experiment, the laser beam 61 is irradiated along the m-axis of the sapphire substrate. For example, even when the laser beam 61 is irradiated along the a-axis of the sapphire substrate, it is considered that the same result as that of FIG. 10 is obtained.

  For example, when the breaking strength N1 is relatively small as in the case of the sample SP14, unintended “cracks” occur in the substrate 50 after the first irradiation step is performed. On the other hand, when the breaking strength N1 is high, occurrence of unintended “cracks” can be suppressed in the substrate 50 after the first irradiation step is performed.

By reducing the laser irradiation pitch Lp, a high breaking strength N1 can be obtained. For example, when the laser irradiation pitch Lp is 1.5 μm or less, a breaking strength N1 higher than 3.8 N is obtained. In the substrate 50 after performing the first irradiation step, occurrence of unintended “cracks” can be further suppressed.
When the laser irradiation pitch Lp is wider than a predetermined value, the formed cracks are hardly connected to each other, and the substrate 50 tends to be hardly broken. For this reason, the present inventors have considered that the substrate 50 can be easily broken by reducing the laser irradiation pitch Lp. However, as described above, it has been found that actually, by reducing the laser irradiation pitch Lp, the breaking strength N1 increases, and unintended “cracking” of the substrate 50 is suppressed. The reason why unintended “cracking” was suppressed is that a plurality of modified regions 53 were densely formed inside the substrate 50 on the scanning line of the laser beam 61, and the substrate 50 became hard to be broken by overlapping each other. It is considered to be.

  In the embodiment, the laser irradiation pitch Lp (that is, the first irradiation pitch Lp1) in the first irradiation step is reduced. For example, the first irradiation pitch Lp1 is 2.5 μm or less. Thereby, a high breaking strength N1 is obtained, and unintended “cracking” can be suppressed. Thereby, for example, the state of irradiation (depth of the focal point) of the laser beam 61 in the second irradiation step is stabilized.

  In the embodiment, the first irradiation pitch Lp1 is 1.0 μm or more. Thereby, for example, damage to the semiconductor structure 51 due to the laser light in the laser light irradiation step can be suppressed. In addition, the time required for the laser beam irradiation step can be prevented from becoming long, and the productivity can be improved.

  In the embodiment, for example, the first irradiation pitch Lp1 is preferably smaller than the second irradiation pitch Lp2. Thereby, unintended “cracks” can be suppressed after the first irradiation step.

  For example, the second irradiation pitch Lp2 is not less than 5.0 μm and not more than 12.0 μm, preferably not less than 5.0 μm and not more than 7.0 μm. When the second irradiation pitch Lp2 is equal to or more than 5.0 μm, for example, when separating the substrate, a line serving as a starting point of the separation easily becomes linear. When the second irradiation pitch Lp2 is 12.0 μm or less, for example, it is possible to prevent the cracks CR from the modified region 53 from being easily connected to each other, and the separation of the substrate 50 becomes easy.

  As described above, in the embodiment, the first pitch P1 (the pitch of the plurality of first lines L1 in the second direction D2) is 0.7 mm or more. The first pitch P1 is preferably 0.7 mm or more and 3 mm or less, more preferably 0.9 mm or more and 2.5 mm or less, and still more preferably 1 mm or more and 2 mm or less. When the first pitch P1 is 0.7 mm or more, a relatively large force acts on the portion of the substrate 50 where the modified region 53 is formed, and unintended “cracks” are likely to occur. This is considered to be due to the fact that when the wafer 50W has a warp due to stress and the first pitch P1 increases, the amount of warp between the adjacent first lines D1 becomes relatively large, and the warp results. As a result, it is considered that an unintended “crack” tends to occur in the portion where the modified region 53 is formed after the first irradiation step or during the first irradiation step. In the present embodiment, the first irradiation pitch Lp1 is narrowed. As a result, the breaking strength N1 increases, and even when the first pitch P1 is relatively large, unintended “cracking” can be suppressed.

  As described above, the first irradiation pitch Lp1 is preferably smaller than the second irradiation pitch Lp2. At this time, in one example, the first line L1 (first direction D1) is along the m-axis, and the second line L2 (second direction D2) is along the a-axis. In another example, the first line L1 (first direction D1) is along the a-axis, and the second line L2 (second direction D2) is along the m-axis. In still another example, the first line L1 (first direction D1) may be inclined with respect to the a-axis, and the second line L2 (second direction D2) may be inclined with respect to the a-axis.

  In the embodiment, it is particularly preferable that the first direction D1 (first line L1) is along the m-axis and the second direction D2 (second line L2) is along the a-axis. This is because the scanning of the laser beam 61 is performed along the m-axis, as described below, so that even if the laser irradiation pitch Lp (first irradiation pitch Lp1) is reduced, the line (the starting point of separation) becomes (Described later) tends to be linear.

  Hereinafter, an example of an experimental result when the laser beam 61 is scanned along the a-axis will be described.

FIG. 11 and FIG. 12 are micrograph images illustrating the experimental results regarding the method of manufacturing the light emitting device.
These figures show micrograph images of the samples SP21, SP22, and SP23. In these samples, the laser irradiation pitch Lp of the laser beam 61 is different from each other. In these samples, the laser beam 61 is scanned along the Y-axis direction. In this experiment, the Y-axis direction is along the a-axis of the sapphire substrate. The X-axis direction is along the m-axis of the sapphire substrate.

  The laser irradiation pitch Lp of the sample SP21 is 12 μm. The laser irradiation pitch Lp of the sample SP22 is 10 μm. The laser irradiation pitch Lp of the sample SP23 is 8 μm. In FIG. 11, the focus of the photograph is located at the depth of the modified region 53. In FIG. 12, the focus of the photograph is located on the surface (first surface 50a in this example) of the substrate 50 (sapphire substrate).

  As can be seen from FIG. 11, in the sample SP21 having a large laser irradiation pitch Lp, a line 53L that linearly connects the plurality of modified regions 53 is observed. This line 53L is considered to correspond to the crack CR (or the origin of the crack CR). Also in the sample SP22 having the medium laser irradiation pitch Lp, a line 53L that linearly connects the modified regions 53 is observed in a part of the plurality of modified regions 53. However, this line 53L is bent as compared with the sample SP21. In the sample SP23 having the small laser irradiation pitch Lp, the line 53L that linearly connects the plurality of modified regions 53 is not substantially observed. In the sample SP23, a curved line 53X passing around the plurality of modified regions 53 is observed.

  As can be seen from FIG. 12, on the surface (first surface 50a) of the sapphire substrate, a clear line 53L along the first direction D1 is observed in the sample SP21 having a large laser irradiation pitch Lp. This line 53L is considered to correspond to the crack CR (or the origin of the crack CR). In the sample SP22 having the medium laser irradiation pitch Lp, the linearity of the line 53L is low, and a part of the line 53L is inclined with respect to the first direction D1. In the sample SP23 having a small laser irradiation pitch Lp, the line 53L is further unclear, and a part of the line 53L is greatly inclined with respect to the first direction D1.

FIG. 13 is a schematic view illustrating experimental results on a method for manufacturing a light-emitting element.
FIG. 13 schematically shows the lines 53L and 53X in the substrate 50 estimated from the micrographs of FIGS. 11 and 12.

  As shown in FIG. 13, in the sample SP21 having a large laser irradiation pitch Lp, a line 53L connecting the lattice points 54 of the sapphire crystal along the second direction D2 is generated. In the sample SP23 having a small laser irradiation pitch Lp, it is considered that, in addition to the line 53L, a line 53X that passes through the lattice point 54 of the sapphire crystal and extends in a direction inclined with respect to the second direction D2 is generated. It is considered that an intermediate state between the sample SP21 and the sample SP23 occurs in the sample SP22 having the intermediate laser irradiation pitch Lp.

  Thus, when the laser irradiation pitch Lp is large, a line 53L that connects the lattice points 54 of the sapphire crystal along the second direction D2 is formed. On the other hand, when the laser irradiation pitch Lp is small, a line 53X extending in a direction inclined with respect to the second direction D2 is likely to occur. The line 53X is a meandering line shape. When the meandering line 53X occurs, for example, when the substrate 50 is separated, the cut surface may not be linear.

  Thus, in the case of irradiating the laser beam 61 along the a-axis, if the laser irradiation pitch Lp is reduced, the meandering line 53X is likely to occur. This is considered to be a phenomenon unique to hexagonal crystals.

  On the other hand, when irradiating the laser beam 61 along the m-axis, the meandering line 53X hardly occurs even when the laser irradiation pitch Lp is reduced.

  From the above, in the embodiment, in the first irradiation step in which the laser irradiation pitch Lp is small, it is preferable that the laser beam 61 is scanned not along the a-axis but along the m-axis. At this time, in the second irradiation step, it is preferable that the laser beam 61 is scanned along the a-axis. This makes it possible to reduce the laser irradiation pitch Lp and suppress unintended “cracks”. Further, the generation of the meandering line 53X can be suppressed. As a result, a method for manufacturing a light-emitting element that can improve productivity can be provided.

  In the embodiment, the output of the laser beam 61 in the first irradiation step and the second irradiation step is preferably 100 mW or more and 300 mW or less, and more preferably 100 mW or more and 150 mW or less. If the output is higher than 300 mW, for example, the semiconductor structure 51 (for example, the light emitting element 51e) may be damaged. If the output is lower than 100 mW, for example, it is difficult to form the modified region 53 or it is difficult to extend a crack from the modified region 53. For this reason, separation of the substrate 50 becomes difficult. When the output is not less than 100 mW and not more than 300 mW, for example, easy separation is possible while suppressing damage to the semiconductor structure 51.

FIG. 14 is a schematic view illustrating a part of another method for manufacturing the light emitting device according to the embodiment.
FIG. 14 illustrates the irradiation of the laser beam 61. In this example, the focal point of the laser beam 61 is at a plurality of depth positions on the substrate 50. For example, the substrate 50 is irradiated with the laser beam 61 by scanning a plurality of times. For example, in a plurality of scans, the depth position of the focal point of the laser beam 61 is changed. Thereby, for example, a group of a plurality of modified regions 53 and a group of a plurality of modified regions 53A are formed. The positions of the plurality of reforming regions 53 in the Z-axis direction are different from the positions of the plurality of reforming regions 53A in the Z-axis direction.

  As described above, in the first irradiation step, the laser beam 61 may be applied to a plurality of positions in the depth direction (Z-axis direction) from the first surface 50a to the second surface 50b. Thereby, for example, the generation of the meandering line 53X can be more stably suppressed.

  According to the embodiment, it is possible to provide a method for manufacturing a light emitting element that can improve productivity.

  In the specification of the present application, “vertical” and “parallel” include not only strictly vertical and strictly parallel, but also include, for example, variations in a manufacturing process, and may be substantially vertical and substantially parallel. Good.

  The embodiments of the invention have been described with reference to examples. However, the present invention is not limited to these specific examples. For example, the present invention can be similarly implemented by appropriately selecting a specific configuration of a wafer, a substrate, a semiconductor structure, a light emitting element, a laser, and the like used in a method for manufacturing a light emitting element from a known range. However, as long as a similar effect can be obtained, it is included in the scope of the present invention.

  A combination of any two or more elements of each specific example within a technically possible range is also included in the scope of the present invention as long as the gist of the present invention is included.

  In addition, based on the method for manufacturing a light-emitting element described above as an embodiment of the present invention, all methods for manufacturing a light-emitting element that can be implemented by a person skilled in the art by appropriately changing the design, as long as the gist of the present invention is included, It belongs to the scope of the present invention.

  In addition, within the scope of the concept of the present invention, those skilled in the art can come up with various modified examples and modified examples, and it is understood that these modified examples and modified examples also fall within the scope of the present invention. .

  50: substrate, 50W: wafer, 50a: first surface, 50b: second surface, 51: semiconductor structure, 51e: light emitting element, 51r: region, 52: bar, 53, 53A: modified region, 53L, 53X ... Line, 53a, 53b: Modified region, 54: Lattice point, 55: Orientation flat, 61: Laser beam, 61a, 61b: First and second positions, AR: Arrow, CR: Crack, D1, D2: First L1, L2: First and second lines, Lp: Laser irradiation pitch, Lp1, Lp2: First and second irradiation pitch, N1: Breaking strength, P1, P2: First and second pitch, SP11 to SP14, SP21 to SP23 ... samples

Claims (5)

Irradiating a laser beam to the substrate of a wafer including a substrate made of sapphire and having a first surface and a second surface, and a semiconductor structure provided on the second surface, and forming a plurality of modified regions inside the substrate; A laser light irradiation step of forming
A separation step of separating the wafer into a plurality of light emitting elements after the laser light irradiation step,
With
The laser light irradiation step,
A first irradiation step of scanning the laser beam along a plurality of first lines, wherein the plurality of first lines extend in a first direction parallel to the first surface and along the m-axis of the sapphire ; A first irradiation step parallel to the first surface and arranged in a second direction along the a-axis of the sapphire ;
A second irradiation step of scanning the laser light along a second line extending in the second direction after the first irradiation step;
Including
In the first irradiation step,
The laser beam is applied to a plurality of positions along the first direction, and a first irradiation pitch of the plurality of positions along the first direction is 2.5 μm or less,
Pitch in the second direction of the plurality of first line is state, and are more 0.7 mm,
In the second irradiation step, the laser light is irradiated to a plurality of positions along the second direction, and a second irradiation pitch of the plurality of positions along the second direction is larger than the first irradiation pitch. ,
The method of manufacturing a light emitting device , wherein the plurality of modified regions formed along the first line overlap each other . The second surface, the is a c-plane of sapphire, the method of manufacturing the light emitting device of claim 1, wherein. It said second irradiation pitch is less than 5.0 .mu.m 12.0 .mu.m, a manufacturing method of a light emitting device according to claim 1 or 2. The output of the laser light in the first irradiation step and the second irradiation step is 100mW or more 300mW or less, the method of manufacturing the light emitting device according to any one of claims 1-3. The light emitting device according to any one of claims 1 to 4 , wherein in the first irradiation step, the laser light is applied to a plurality of positions in a depth direction from the first surface to the second surface. Manufacturing method.