KR102539062B1 - Method of manufacturing a light emitting element - Google Patents

Abstract

[Problem] To provide a method for manufacturing a light emitting device capable of improving productivity.
[Solution Means] According to the embodiment, a method for manufacturing a light emitting element includes a laser beam irradiation step of irradiating a substrate of a wafer including a substrate and a semiconductor structure with a laser beam to form a plurality of modified regions inside the substrate; After the light irradiation process, a separation process of separating the wafer into a plurality of light emitting elements is included. The laser beam irradiation step includes a first irradiation step of scanning a laser beam 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 crossing the first direction. A laser beam irradiation process includes a 2nd irradiation process of scanning a laser beam along the 2nd line extended in the 2nd direction after a 1st irradiation process. In the first irradiation step, the laser beam is irradiated to a plurality of positions along the first direction, the first irradiation pitch of the plurality of positions is 2.5 μm or less, and the pitch of the plurality of first lines in the second direction is 0.7 mm or more.

Description

Manufacturing method of light emitting device {METHOD OF MANUFACTURING A LIGHT EMITTING ELEMENT}

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

In a method of manufacturing a light emitting device in which a compound semiconductor functioning as a light emitting layer is laminated on a substrate, a method of forming an element isolation line by irradiating a substrate with a laser has been proposed. In the manufacturing method of a light emitting element, improvement of productivity is requested|required.

Japanese Patent No. 5119463

The present invention provides a method for manufacturing a light emitting device capable of improving productivity.

According to one aspect of the present invention, a method of manufacturing a light emitting device includes irradiating a laser beam to a substrate of a wafer including a substrate having first and second surfaces and a semiconductor structure provided on the second surface, A laser beam irradiation step of forming a plurality of modified regions inside the substrate, and a separation step of separating the wafer into a plurality of light emitting elements after the laser beam irradiation step. The laser beam irradiation step includes a first irradiation step of scanning the laser beam 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 crossing the first direction. The laser beam irradiation step includes, after the first irradiation step, a second irradiation step of scanning the laser beam along a second line extending in the second direction. In the first irradiation step, the laser beam is irradiated to a plurality of positions along the first direction, a first irradiation pitch of the plurality of positions along the first direction is 2.5 μm or less, and the plurality of positions The pitch of the first line in the second direction is 0.7 mm or more.

According to one aspect of the present invention, a method for manufacturing a light emitting device capable of improving productivity is provided.

[Fig. 1] It is a flowchart illustrating a method of manufacturing a light emitting element according to an embodiment.
[ Fig. 2 ] It is a schematic diagram illustrating a wafer used in a method for manufacturing a light emitting element according to an embodiment.
[Fig. 3] It is a schematic diagram illustrating a wafer used in the method for manufacturing a light emitting element according to an embodiment.
[ Fig. 4 ] It is a schematic diagram illustrating a part of a method for manufacturing a light emitting device according to an embodiment.
[Fig. 5] It is a schematic plan view illustrating a part of a method for manufacturing a light emitting element according to an embodiment.
[ Fig. 6 ] It is a schematic plan view illustrating a part of a method for manufacturing a light emitting element according to an embodiment.
[ Fig. 7 ] It is a schematic plan view illustrating a part of a method for manufacturing a light emitting element according to an embodiment.
[ Fig. 8 ] It is a schematic plan view illustrating a part of a method for manufacturing a light emitting element according to an embodiment.
[Fig. 9] Fig. 9 is a schematic cross-sectional view illustrating a part of a method for manufacturing a light emitting element.
[Fig. 10] is a graph illustrating experimental results regarding a manufacturing method of a light emitting device.
[Fig. 11] A photomicrograph showing experimental results regarding a manufacturing method of a light emitting element.
[Fig. 12] A photomicrograph image illustrating experimental results regarding a manufacturing method of a light emitting element.
[ Fig. 13 ] It is a schematic diagram illustrating experimental results regarding a manufacturing method of a light emitting element.
[Fig. 14] It is a schematic diagram illustrating a part of another manufacturing method of the light emitting element according to the embodiment.

EMBODIMENT OF THE INVENTION Below, each embodiment of this invention is described, referring drawings.

In addition, the drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the size between parts, and the like are not necessarily the same as those in reality. In addition, even when the same part is shown, there are cases in which dimensions or ratios of each other are shown differently depending on the drawings.

In addition, in this specification, the same code|symbol is attached|subjected to the same element as what was mentioned above with respect to the already-explained drawing, and detailed description is abbreviate|omitted suitably.

1 is a flowchart illustrating a method for manufacturing a light emitting element according to an embodiment.

2 and 3 are schematic diagrams illustrating wafers used in the method for manufacturing a light emitting element according to the embodiment. FIG. 2 is a cross-sectional view along line II-II of FIG. 3 . FIG. 3 is a plan view seen from arrow AR in FIG. 2 .

As shown in Fig. 1, the method for manufacturing a light emitting element according to the embodiment includes a laser beam irradiation step (step S110) and a separation step (step S120). A laser beam irradiation process includes a 1st irradiation process (step S111) and a 2nd irradiation process (step S112). The separation process includes a first separation process (step S121) and a second separation process (step S122).

In the laser irradiation step, a laser beam is irradiated to the wafer. Examples of wafers will be described below.

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

The direction from the second surface 50b to the first surface 50a is referred to as the Z-axis direction. One direction perpendicular to the Z-axis direction is the X-axis direction. A direction perpendicular to the Z-axis direction and the X-axis direction is referred to as the Y-axis direction. The first surface 50a and the second surface 50b extend along the X-Y plane. The Z-axis direction corresponds to the thickness direction (eg, 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 intersects 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 follows the Y-axis direction.

The substrate 50 is made of sapphire, for example. The substrate 50 is, for example, a sapphire substrate (eg, 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 extension direction of the orientation flat 55 follows the first direction D1 of the wafer 50W. In the embodiment, the relationship between the first direction D1 and the extension direction of the orientation flat 55 is arbitrary. The relationship between the second direction D2 and the extension direction of the orientation flat 55 is arbitrary.

A laser beam is irradiated to such a wafer 50W. The wafer 50W is separated along the boundary of the plurality of regions 51r. A plurality of light emitting elements are obtained from the plurality of regions 51r.

4 is a schematic diagram illustrating a part of a method for manufacturing a light emitting element according to an embodiment.

4 illustrates irradiation of a laser beam. As shown in FIG. 4 , the laser beam 61 is irradiated to the substrate 50 of the wafer 50W. In this example, the laser beam 61 enters the substrate 50 from the first surface 50a.

The laser light 61 is emitted in pulse form. As a laser light source, a Nd:YAG laser, a titanium sapphire laser, a Nd:YVO ₄ laser, or a Nd:YLF laser, etc. are used, for example. The wavelength of the laser light 61 is the wavelength of light passing through the substrate 50 . The laser light 61 is, for example, a laser light having a peak wavelength in a range of 800 nm or more and 1200 nm or less.

The laser beam 61 is scanned along a direction parallel to the X-Y plane. For example, the relative position of the laser light 61 and the substrate 50 is changed along a direction parallel to the X-Y plane. The position of the converging point of the laser beam 61 along the Z-axis direction (position when the substrate 50 is the reference) may be changeable.

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

A plurality of modified regions 53 are formed inside the substrate 50 by the irradiation of the laser beam 61 . The laser light 61 is condensed inside the substrate 50 . At a position of a specific depth inside the substrate 50, energy by the laser light 61 is concentrated. As a result, a plurality of modified regions 53 are formed. The pitch of the converging points 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 embrittled by laser irradiation in the inside of the substrate 50 .

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

In this way, in the laser beam irradiation step (step S110), the substrate 50 is irradiated with the laser beam 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 process (step S120), the wafer 50W is separated into a plurality of light emitting elements after the laser beam irradiation process. For example, by performing separation along two directions, the wafer 50W is separated into a plurality of light emitting elements.

An example of a laser beam irradiation step will be described below.

5 is a schematic plan view illustrating a part of a method for manufacturing a light emitting element according to an embodiment.

5 illustrates the first irradiation process (step S111). As shown in FIG. 5, in the 1st irradiation process, the laser beam 61 is scanned along the some 1st line L1.

The plurality of first lines L1 extend in the first direction D1 and are arranged in the second direction D2. As already described, the first direction D1 is parallel to the first surface 50a. The second direction D2 is parallel to the first surface 50a and intersects 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 embodiment, the 1st pitch P1 is 0.7 mm or more, for example. 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, still more preferably 1 mm or more and 2 mm or less.

The plurality of first lines L1 follow the boundary between the 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 irradiated 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 to each other in the first direction D1 follow 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 a method for manufacturing a light emitting element according to an embodiment.

6 illustrates the second irradiation process (step S112). As shown in Fig. 6, in the second irradiation step, the laser beam 61 is scanned along the plurality of second lines L2.

The plurality of second lines L2 extend in the second direction D2. The plurality of second wires 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 follow the boundary between the plurality of regions 51r (see FIG. 3 ) arranged in the first direction D1, for example.

In the irradiation of the laser beam 61 along one of the plurality of second lines L2 in the second irradiation step, the laser beam 61 is irradiated 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 adjacent second positions 61b in the second direction D2 follow the second direction D2.

In one example, the 1st irradiation pitch Lp1 is smaller than the 2nd irradiation pitch Lp2.

In one example, the 1st pitch P1 (refer FIG. 5) is smaller than the 2nd pitch P2 (refer FIG. 6). The 1st pitch P1 may be made larger than the 2nd pitch P2, and you may make the 1st pitch P1 and the 2nd pitch P2 the same.

Hereinafter, an example of the separation process will be described.

Fig. 7 is a schematic plan view illustrating a part of a method for manufacturing a light emitting element according to an embodiment.

7 illustrates the first separation process. In the first separation process, the wafer 50W is separated into a 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 a plurality of bars 52 . In the embodiment, one bar 52 is a state in which a plurality of regions 51r are arranged in the first direction D1.

Fig. 8 is a schematic plan view illustrating a part of a method for manufacturing a light emitting element according to an embodiment.

8 illustrates a second separation process. The second separation process is performed after the first separation process. In the second separation process, after the first separation process, the bar 52 is separated into a 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 separation is performed, for example, by cutting.

As already described, 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 mentioned above, in the laser beam irradiation process, the 1st irradiation process (step S111) and the 2nd irradiation process (step S112) are implemented. It has been found that there are cases where the substrate 50 (wafer 50W) is irradiated with the laser beam 61 in an undesirable state when the second irradiation process is performed after the first irradiation process. This example will be described below.

Fig. 9 is a schematic cross-sectional view illustrating a part of a method for manufacturing a light emitting element.

FIG. 9 exemplifies the irradiation state of the substrate 50 and the laser beam 61 when the second irradiation process is performed after the first irradiation process. In this example, the first irradiation process was not performed under appropriate conditions.

As shown in FIG. 9, in the 1st irradiation process, the laser beam 61 is irradiated along the 1st line L1. As a result, a plurality of modified regions 53a are formed inside the substrate 50 . In FIG. 9 , a cross section by a plane including the second direction D2 and the Z-axis direction is shown. For this reason, one of the plurality of modified regions 53a is shown. 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 cracks CR are generated in the substrate 50, but the main surface of the substrate 50 ( For example, the first surface 50a) is continuous and is one plane. That is, the substrate 50 is not separated from the crack CR as a starting point only by irradiating the laser beam 61 . Cracks CR are generated starting from the plurality of modified regions 53.

On the other hand, when the irradiation conditions of the laser beam 61 are inappropriate, a plurality of modified regions 53a are formed in the substrate 50, and cracks (CR) occur in the substrate 50. The first surface 50a of the substrate 50 is separated from the first line L1 by the crack CR. The two first surfaces 50a formed separately are not continuous. The two first surfaces 50a are inclined to each other. In this way, when the irradiation conditions of the laser beam 61 are inappropriate, unintentional "cracking" occurs in the substrate 50.

Due to this unintentional "crack", the first surface 50a of the substrate 50 becomes uneven. By "cracking", the first surface 50a is inclined. In this state, when the second irradiation step is performed, the depth position of the converging point of the laser beam 61 in the substrate 50 becomes not constant. For this reason, the depth position of the plurality of modified regions 53b formed in the second irradiation step is not constant.

As shown in Fig. 9, for example, in the region close to the crack CR, the position of the modified region 53b is deep. On the other hand, in the region far from the crack CR, the position of the modified region 53b is shallow. For this reason, it becomes difficult to carry out the separation (second separation process) based on the second irradiation process in a desired state. For example, defects tend to occur and product yield tends to decrease, making it difficult to sufficiently increase productivity. In the region close to the crack CR, the position where the laser beam 61 is focused becomes close to the semiconductor structure 51. For this reason, damage by the laser beam 61 arises in the semiconductor structure 51.

In this way, it was found that when the conditions of the first irradiation step were inappropriate, unintended “cracking” occurred, and as a result, it was difficult to perform the second irradiation step under appropriate conditions.

In embodiment, the conditions of the 1st irradiation process are made appropriate. Thereby, for example, unintentional "cracking" can be suppressed. Thereby, the 2nd irradiation process can be performed under appropriate conditions. It is possible to provide a method for manufacturing a light emitting device capable of improving productivity.

Hereinafter, the experimental result regarding the conditions of the 1st irradiation process is demonstrated.

In the experiment, as the substrate 50, a sapphire substrate having a thickness of 200 μm was used. The planar shape of the sample is a square with a side length of 10.2 mm. The central part of the sample was irradiated with laser light 61 under different irradiation conditions. A laser beam 61 was irradiated along the m-axis of the sapphire substrate. After irradiation with the laser beam 61, the breaking strength of the sample was measured. In the measurement of breaking strength, the pressing 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, among the irradiation conditions of the laser beam 61, in samples SP11-SP14, the power and the laser pulse width are the same value, and the value of the laser irradiation pitch is changed.

10 is a graph illustrating experimental results regarding a manufacturing method of a light emitting element.

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 the samples SP11 to SP14 shown in FIG. 10 is an average value of values obtained by measuring three times for each of the samples SP11 to SP14. The breaking strength N1 in the sample (SP11) was 3.8 N. The breaking strength N1 in the sample (SP12) was 2.3 N. The breaking strength N1 in the sample (SP13) was 1.6 N. The breaking strength N1 in the sample (SP14) was 0.6 N.

As can be seen from FIG. 10 , the breaking strength N1 greatly depends on the laser irradiation pitch Lp. By making the laser irradiation pitch Lp small, high breaking strength N1 is obtained. In the above experiment, the laser beam 61 is irradiated along the m-axis of the sapphire substrate. For example, it is thought that the result similar to FIG. 10 can be obtained also when the laser beam 61 is irradiated along the a-axis of a sapphire substrate.

For example, when the breaking strength N1 is relatively small as in the sample SP14, unintended "cracking" occurs in the substrate 50 after the first irradiation step is performed. On the other hand, in the case where the breaking strength N1 is high, in the substrate 50 after performing the first irradiation step, occurrence of unintentional "cracking" can be suppressed.

By making the laser irradiation pitch Lp small, 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 can be obtained. In the substrate 50 after performing the first irradiation step, unintentional occurrence of "cracking" can be further suppressed.

When the laser irradiation pitch Lp is set larger than a predetermined value, it is difficult for cracks formed to connect to each other, and the substrate 50 tends to be difficult to split. For this reason, the inventors of the present invention thought that the substrate 50 becomes easily divided by narrowing the laser irradiation pitch Lp. However, as described above, in practice, it has been found that by narrowing the laser irradiation pitch Lp, the breaking strength N1 increases and unintentional "cracking" of the substrate 50 is suppressed. The reason why unintentional "cracking" is suppressed is that a plurality of modified regions 53 are densely formed inside the substrate 50 on the scanning line of the laser beam 61, and they overlap each other, thereby forming the substrate 50 I think this is because it has become difficult to separate.

In the embodiment, the laser irradiation pitch Lp (ie, the first irradiation pitch Lp1) in the first irradiation step is made small. For example, the 1st irradiation pitch Lp1 is 2.5 micrometers or less. Thereby, high breaking strength N1 can be obtained and unintentional "cracking" can be suppressed. Thereby, for example, the irradiation state of the laser beam 61 in the second irradiation step (the depth of the converging point) 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 by the laser beam can be suppressed in the laser beam irradiation step. Moreover, it can suppress that the time required for a laser beam irradiation process becomes long, and productivity can be improved.

In the embodiment, for example, the first irradiation pitch Lp1 is preferably smaller than the second irradiation pitch Lp2. Thereby, unintentional "crack" after the 1st irradiation process can be suppressed.

For example, the second irradiation pitch Lp2 is 5.0 μm or more and 12.0 μm or less, preferably 5.0 μm or more and 7.0 μm or less. When the second irradiation pitch Lp2 is 5.0 μm or more, for example, when separating the substrates, the line serving as the starting point of the separation tends to be straight. When the second irradiation pitch Lp2 is 12.0 μm or less, it is possible to prevent cracks CR from the modified region 53 from becoming difficult to connect to each other, and separation of the substrate 50 becomes easy, for example. .

As already explained, 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 unintentional "cracking" tends to occur. This is because when the wafer 50W has warpage due to stress and the first pitch P1 is increased, the amount of warpage in each of the adjacent first lines D1 becomes relatively large, resulting in a warpage caused by the warpage. It is thought to be As a result, it is considered that after the first irradiation step is performed or during the first irradiation step, there is a tendency for unintentional "cracking" to occur easily in the portion where the modified region 53 is formed. In this embodiment, the 1st irradiation pitch Lp1 is made narrow. Thereby, breaking strength N1 becomes large, and even if it is a case where 1st pitch P1 is comparatively large, unintentional "crack" 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 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 also be inclined with respect to the a-axis.

In the embodiment, it is particularly preferred 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. As described below, this is because the laser beam 61 is scanned along the m-axis, so even if the laser irradiation pitch Lp (first irradiation pitch Lp1) is reduced, the line serving as the starting point of separation ( described later) tends to be linear.

Hereinafter, examples of experimental results when the laser light 61 is scanned along the a-axis will be described.

11 and 12 are photomicrographs illustrating experimental results regarding a manufacturing method of a light emitting element.

In these figures, photomicrograph images of the sample SP21, sample SP22, and sample SP23 are shown. In these samples, the laser irradiation pitch Lp of the laser light 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 follows the a-axis of the sapphire substrate. The X-axis direction follows the m-axis of the sapphire substrate.

The laser irradiation pitch Lp in the sample SP21 is 12 μm. The laser irradiation pitch Lp in the sample SP22 is 10 μm. The laser irradiation pitch Lp in 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 of the substrate 50 (sapphire substrate) (in this example, the first surface 50a).

As can be seen from FIG. 11 , in the sample SP21 having a large laser irradiation pitch Lp, a line 53L linearly connecting a plurality of modified regions 53 is observed. It is thought that this line 53L corresponds to the crack CR (or the origin of the crack CR). Also in the sample SP22 having an intermediate laser irradiation pitch Lp, a line 53L linearly connecting the modified regions 53 is observed in a part of the plurality of modified regions 53 . However, compared with sample SP21, this line 53L is bent. In the sample SP23 having a small laser irradiation pitch Lp, a line 53L linearly connecting 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 , in the sample SP21 having a large laser irradiation pitch Lp on the surface of the sapphire substrate (first surface 50a), a clear line along the first direction D1 ( 53L) is observed. It is thought that this line 53L corresponds to the crack CR (or the origin of the crack CR). In sample SP22 with an intermediate laser irradiation pitch Lp, the linearity of this line 53L becomes low, and a part of line 53L inclines with respect to the 1st direction D1. In the sample SP23 with a small laser irradiation pitch Lp, the line 53L becomes more unclear, and a part of the line 53L is greatly inclined with respect to the first direction D1.

Fig. 13 is a schematic diagram illustrating experimental results regarding a manufacturing method of a light emitting element.

FIG. 13 schematically shows 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 formed. In the sample SP23 having a small laser irradiation pitch Lp, in addition to the line 53L, a line 53X passing through the lattice point 54 of the sapphire crystal and extending in a direction inclined to the second direction D2 ) is thought to occur. In the sample SP22 with an intermediate laser irradiation pitch Lp, it is thought that an intermediate state between the sample SP21 and the sample SP23 arises.

In this way, when the laser irradiation pitch Lp is large, a line 53L connecting 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, lines 53X extending in a direction inclined with respect to the second direction D2 tend to occur. The line 53X is a meandering line shape. When a meandering line 53X is formed, for example, when the substrate 50 is separated, the cut surface may not be straight.

In this way, when the laser beam 61 is irradiated along the a-axis, if the laser irradiation pitch Lp is made small, meandering lines 53X tend to occur. This is considered to be a phenomenon specific to hexagonal crystals.

On the other hand, when irradiating the laser beam 61 along the m-axis, even when the laser irradiation pitch Lp is made small, the meandering line 53X is unlikely to occur.

From the foregoing, 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 be scanned along the m-axis instead of the a-axis. At this time, in the second irradiation step, it is preferable that the laser beam 61 is scanned along the a-axis. Thereby, the laser irradiation pitch Lp can be made small, and unintentional "cracking" can be suppressed. Furthermore, generation of the meandering line 53X can be suppressed. As a result, it is possible to provide a method for manufacturing a light emitting device capable of further improving productivity.

In embodiment, it is preferable that the output of the laser beam 61 in a 1st irradiation process and a 2nd irradiation process is 100 mW or more and 300 mW or less, Preferably it is 100 mW or more and 150 mW or less. If the output is higher than 300 mW, damage may occur to the semiconductor structure 51 (eg, the light emitting element 51e), for example. If the output is lower than 100 mW, the formation of the modified region 53 becomes difficult, or the propagation of cracks from the modified region 53 becomes difficult, for example. For this reason, separation of the substrate 50 becomes difficult. When the output is 100 mW or more and 300 mW or less, for example, easy separation is possible while suppressing damage to the semiconductor structure 51 .

Fig. 14 is a schematic diagram illustrating a part of another manufacturing method of the light emitting element according to the embodiment.

14 illustrates irradiation of the laser beam 61. In this example, the convergence points of the laser beam 61 are located at a plurality of depth positions of the substrate 50 . For example, the laser beam 61 is scanned multiple times to irradiate the substrate 50 . For example, in multiple times of scanning, the depth position of the converging point of the laser beam 61 is changed. In this way, 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 modified regions 53 in the Z-axis direction are different from the positions of the plurality of modified regions 53A in the Z-axis direction.

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

According to the embodiment, a method for manufacturing a light emitting element capable of improving productivity can be provided.

In the present specification, "perpendicular" and "parallel" are not only strictly perpendicular and strictly parallel, but also include variations in manufacturing processes, for example, and may be substantially perpendicular and substantially parallel.

In the above, the embodiment of the present invention was described with reference to specific examples. However, the present invention is not limited to these specific examples. For example, with respect to each specific configuration of a wafer, a substrate, a semiconductor structure, a light emitting element, and a laser used in a method for manufacturing a light emitting element, a person skilled in the art can similarly carry out the present invention by appropriately selecting from the known range, and the same As long as the effect of can be obtained, it is included in the scope of the present invention.

In addition, combinations of any two or more elements from each specific example within a technically possible range are 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 above-described method for manufacturing a light emitting device as an embodiment of the present invention, all methods for manufacturing a light emitting device that can be implemented by appropriately designing changes by those skilled in the art are also applicable to the present invention, as long as the gist of the present invention is included. belong to the range

In addition, in the scope of the idea of the present invention, those skilled in the art can conceive of various examples of changes and modifications, and it is understood that these examples of changes and modifications also fall within the scope of the present invention.

50: substrate
50W: Wafer
50a: first side
50b: second side
51: semiconductor structure
51e: light emitting element
51r: area
52: bar
53, 53A: reforming area
53L, 53X: line
53a, 53b: reforming region
54: lattice point
55: orientation flat
61: laser light
61a, 61b: first and second positions
AR: arrow
CR: crack
D1, D2: first and second directions
L1, L2: 1st, 2nd line
Lp: laser irradiation pitch
Lp1, Lp2: First and second irradiation pitches
N1: breaking strength
P1, P2: first and second pitches
SP11~SP14, SP21~SP23: Sample

Claims (6)

As a method of manufacturing a light emitting device,
A laser beam is irradiated to a substrate of a sapphire wafer having first and second surfaces and a semiconductor structure provided on the second surface to form a plurality of modified regions inside the substrate. research process,
Separation process of separating the wafer into a plurality of light emitting devices after the laser light irradiation process
to provide,
The laser light irradiation process,
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 arranged in a second direction parallel to the plane and along the a-axis of the sapphire;
A second irradiation process of scanning the laser light along a second line extending in the second direction after the first irradiation process.
including,
In the first irradiation step,
The laser light is irradiated 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,
a pitch of the plurality of first lines in the second direction is 0.7 mm or more;
In the second irradiation step, the laser beam 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 greater than the first irradiation pitch; ,
The plurality of modified regions formed along the first line overlap each other,
A method for manufacturing a light emitting device. delete According to claim 1,
The second surface is a c-side of the sapphire. According to claim 1 or 3,
The second irradiation pitch is 5.0 μm or more and 12.0 μm or less, a method of manufacturing a light emitting element. According to claim 1 or 3,
The method of manufacturing a light emitting element, wherein the output of the laser beam in the first irradiation step and the second irradiation step is 100 mW or more and 300 mW or less. According to claim 1 or 3,
In the first irradiation step, the laser beam is irradiated to a plurality of positions in a depth direction from the first surface to the second surface.

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