JP7360007B2 - Manufacturing method of light emitting device - Google Patents

Description

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

In recent years, light emitting diodes such as white LEDs have become increasingly bright and are widely used as light sources for general lighting, vehicle-mounted applications, and the like. As the applications expand, even higher brightness is required. Patent Document 1 discloses a light emitting device in which a plurality of light emitting diode chips are stacked vertically to increase luminous efficiency per unit area.

Japanese Patent Application Publication No. 2010-41057

However, in the light emitting device disclosed in Patent Document 1, each light emitting diode chip is provided with either a positive or negative electrode, so it is necessary to secure an area for forming one electrode for each light emitting diode chip. However, there is a problem that the formation range of the active layer per unit area becomes smaller.

Furthermore, in a light emitting device in which a plurality of light emitting diodes are stacked, it is necessary to suppress light absorption at the junction between the light emitting diodes and improve the light extraction efficiency of the light emitting device.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for manufacturing a light emitting device in which a plurality of light emitting parts are stacked, in which the formation range of the active layer per unit area is increased and the light extraction efficiency is improved. shall be.

In order to solve the above problems, a method for manufacturing a light emitting device according to an embodiment of the present invention includes a first substrate, a first semiconductor layer of a first conductivity type, and a first active layer on the first substrate. and a second semiconductor layer of a second conductivity type different from the first conductivity type, in order from the first substrate side; a second substrate; A second wafer is prepared on a second substrate, including the fourth semiconductor layer of the second conductivity type, the second active layer, and the third semiconductor layer of the first conductivity type in this order from the second substrate side. a second wafer preparation step, and a first conductive oxide film having a light-transmitting property and electrically connected to the second semiconductor layer on the second semiconductor layer exposed on the surface of the first wafer; a first forming step of forming a first conductive member provided on the first conductive oxide film; and a first forming step of forming a first conductive member provided on the third semiconductor layer of the second wafer; a second forming step of forming a connected second conductive oxide film having light-transmitting properties and a second conductive member provided on the second conductive oxide film; a joining step of joining a second wafer by thermocompression bonding the first conductive member and the second conductive member; and after the joining step, removing the second substrate of the second wafer; an exposing step of exposing the fourth semiconductor layer, and the transmittance of the first conductive member and the second conductive member after the bonding step with respect to the wavelength of light from the first active layer is as follows: The transmittance of the first conductive member and the second conductive member in the first forming step and the second forming step is higher than that of the first conductive member with respect to the wavelength of light from the first active layer.

According to the method for manufacturing a light emitting device according to an embodiment of the present invention configured as described above, in a light emitting device in which a plurality of light emitting parts are stacked, the formation range of the active layer per unit area is increased, A light emitting device with improved light extraction efficiency can be easily manufactured.

1 is a schematic cross-sectional view showing the configuration of a light emitting device according to an embodiment of the present invention. 1 is a schematic cross-sectional view for explaining a method of manufacturing a light emitting device according to an embodiment of the present invention. 1 is a schematic cross-sectional view for explaining a method of manufacturing a light emitting device according to an embodiment of the present invention. 1 is a schematic cross-sectional view for explaining a method of manufacturing a light emitting device according to an embodiment of the present invention. 1 is a schematic cross-sectional view for explaining a method of manufacturing a light emitting device according to an embodiment of the present invention. 1 is a schematic cross-sectional view for explaining a method of manufacturing a light emitting device according to an embodiment of the present invention. 1 is a schematic cross-sectional view for explaining a method of manufacturing a light emitting device according to an embodiment of the present invention. 1 is a schematic cross-sectional view for explaining a method of manufacturing a light emitting device according to an embodiment of the present invention. 1 is a schematic cross-sectional view for explaining a method of manufacturing a light emitting device according to an embodiment of the present invention. 1 is a schematic cross-sectional view for explaining a method of manufacturing a light emitting device according to an embodiment of the present invention. 1 is a schematic cross-sectional view for explaining a method of manufacturing a light emitting device according to an embodiment of the present invention. 1 is a schematic cross-sectional view for explaining a method of manufacturing a light emitting device according to an embodiment of the present invention. 1 is a schematic cross-sectional view for explaining a method of manufacturing a light emitting device according to an embodiment of the present invention.

Hereinafter, a light emitting device according to an embodiment and a method for manufacturing the same will be described with reference to the drawings.

FIG. 1 is a sectional view showing the configuration of a light emitting device according to an embodiment of the present invention.
In the light emitting device of this embodiment, as shown in FIG. 1, a first light emitting section 1 and a second light emitting section 2 provided above the first light emitting section 1 are formed on a substrate 7. The first light emitting section 1 includes a first semiconductor layer 11 of a first conductivity type, a first active layer 12, and a second semiconductor layer 13 of a second conductivity type different from the first conductivity type from the substrate 7 side. Contains in order. The second light emitting section 2 includes a third semiconductor layer 21 of the first conductivity type, a second active layer 22, and a fourth semiconductor layer 23 of the second conductivity type in order from the first light emitting section 1 side. . A first conductive oxide film 4a, a second conductive oxide film 4b, and a conductive member 5 are provided between the first light emitting part 1 and the second light emitting part 2. Light from the first light emitting section 1 is emitted from the fourth semiconductor layer 23 side of the second light emitting section 2 via the first conductive oxide film 4a, the second conductive oxide film 4b, and the conductive member 5. .

In the light emitting device of the embodiment, the first light emitting section 1 is joined to the substrate 7 by a metal layer 6, and between the first light emitting section 1 and the metal layer 6, the first semiconductor layer of the first light emitting section 1 is connected. A second electrode 32 connected to 11 is provided. Thus, for example, by using the conductive substrate 7 as the substrate 7, the light emitting device of this embodiment can supply power to the first light emitting section 1 via the substrate 7. In the light emitting device of this embodiment, as shown in FIG. 1, a first electrode 31 is provided on the upper surface of the fourth semiconductor layer 23 of the second light emitting section 2. Further, as described above, the first conductive oxide film 4a, the second conductive oxide film 4b, and the conductive member 5 are provided between the first light emitting part 1 and the second light emitting part 2, and the first light emitting part 1 and the second light emitting section 2 are electrically connected. As described above, the first light emitting section 1 and the second light emitting section 2 are connected in series between the first electrode 31 and the second electrode 32, and by applying a voltage between the first electrode 31 and the second electrode 32, The first light emitting section 1 and the second light emitting section 2 can be caused to emit light.

Hereinafter, a method for manufacturing a light emitting device according to an embodiment will be described.

<First wafer preparation process>
In the first wafer preparation step, for example, a third substrate 73 made of Si is prepared. Then, as shown in FIG. 2, the second semiconductor layer 13 of the second conductivity type, the first active layer 12, and the first semiconductor layer 11 of the first conductivity type are formed on the third substrate 73. They are formed in order from the substrate 73 side. Note that the second semiconductor layer 13 may be formed on the third substrate 73 with a buffer layer interposed therebetween. The semiconductor layer can be formed, for example, by a known technique such as metal organic chemical vapor deposition (MOCVD), hydride vapor phase epitaxy (HVPE), or molecular beam epitaxial growth (MBE). As the third substrate 73, a substrate on which the respective semiconductor layers constituting the first light emitting section 1 can be stacked can be used, and for example, a Si substrate, a sapphire substrate, a gallium arsenide substrate, a GaN substrate, etc. can be used. I can do it. In this embodiment, it is particularly preferable to use a Si substrate as the third substrate 73, which makes it easier to remove the third substrate 73 in a step to be described later. Since the Si substrate is relatively easy to process and can be removed by wet etching, etc., damage to the semiconductor stack made of semiconductor layers can be reduced compared to the case where the third substrate 73 is removed by laser lift-off. It can be reduced.

Next, as shown in FIG. 3, a second electrode 32 in a predetermined pattern is formed on the first semiconductor layer 11. The second electrode 32 is formed, for example, by a lift-off method using photoresist. For example, a photoresist is formed on a portion of the first semiconductor layer 11 where the second electrode 32 is not formed, and a metal film is formed on the first semiconductor layer 11 and the photoresist using the photoresist as a mask. Then, the second electrode 32 can be formed by removing the photoresist together with the metal film formed on the photoresist.

Next, as shown in FIG. 3, an insulating film 35 is formed in a portion where the second electrode 32 is not formed. For example, the insulating film 35 is formed by forming a photoresist on the first semiconductor layer 11 and the second electrode 32, and using the photoresist as a mask. Then, the photoresist is removed together with the insulating film formed on the second electrode 32. Thereby, the insulating film 35 can be formed in the portion where the second electrode 32 is not formed. The insulating film 35 is provided on the cutting position CL, for example, as shown in FIG. 13, which will be described later. By arranging the insulating film 35 in this manner, it is possible to create a structure in which the second electrode 32 is not exposed from the side surface of the light emitting device due to the insulating film 35. As a result, the occurrence of short circuits on the side surfaces of the light emitting device is suppressed, and reliability can be improved.

Next, as shown in FIG. 4, a metal layer 6 is formed on the second electrode 32 and the insulating film 35 formed on the first semiconductor layer 11. Separately, a first substrate 71 having a metal layer 6 formed on one surface is prepared. Then, as shown in FIGS. 5 and 6, the first substrate 71 is bonded onto the first semiconductor layer 11 via the second electrode 32 and the insulating film 35 by bonding the metal layers 6 together. Here, the first substrate 71 corresponds to the substrate 7 in FIG. The first substrate 71 is attached to a structure in which the second semiconductor layer 13 of the second conductivity type, the first active layer 12, and the first semiconductor layer 11 of the first conductivity type are provided on the third substrate 73. After bonding with layer 6, third substrate 73 is removed, as shown in FIG. The removal of the third substrate 73 is performed, for example, by laser lift-off, which irradiates the vicinity of the interface between the third substrate 73 and the second semiconductor layer 13 with laser light to separate the third substrate 73 and the second semiconductor layer 13. Alternatively, the third substrate 73 is removed by performing wet etching using a solution that can etch the third substrate 73.

The semiconductor stacked structure formed on the third substrate 73 as described above is transferred onto the first substrate 71 via the metal layer 6, the second electrode 32, and the insulating film 35. Through these steps, the first semiconductor layer 11, the first active layer 12, and the second semiconductor layer 13 are sequentially formed on the first substrate 71 from the first substrate 71 side, as shown in FIG. A first wafer 100 having one light emitting section 1 is prepared. That is, in the first wafer 100, the first semiconductor layer 11, the first active layer 12, and the second semiconductor layer 13 are formed on the first substrate 71 via the metal layer 6, the second electrode 32, and the insulating film 35. are stacked in order. In the first wafer 100, the second semiconductor layer 13 is exposed on the surface of the first wafer 100. The second electrode 32 is located between the first substrate 71 and the first semiconductor layer 11 and electrically connects the first substrate 71 and the first semiconductor layer 11. Here, the first substrate 71 is preferably a silicon substrate, and by making the first substrate 71 a silicon substrate, the first substrate 71 can be easily divided in a cutting process to be described later.

<Second wafer preparation process>
In the second wafer preparation step, a second substrate 72 made of Si, for example, is prepared. Then, as shown in FIG. 8, a fourth semiconductor layer 23 of the second conductivity type, a second active layer 22, and a third semiconductor layer 21 of the first conductivity type are formed on the second substrate 72. They are formed in order from the substrate 72 side. Note that the fourth semiconductor layer 23 may be formed on the second substrate 72 with a buffer layer interposed therebetween. In this way, the second light emitting section 2 is formed, in which the fourth semiconductor layer 23, the second active layer 22, and the third semiconductor layer 21 are sequentially formed on the second substrate 72 from the second substrate 72 side. A second wafer 200 is prepared.

<First formation step>
In the first formation step, a first conductive oxide film 4 a electrically connected to the second semiconductor layer 13 is formed on the second semiconductor layer 13 exposed on the surface of the first wafer 100 . Furthermore, a first conductive member 5a is formed on the first conductive oxide film 4a. As shown in FIG. 9, on the second semiconductor layer 13, a first conductive oxide film 4a and a first conductive member 5a are laminated. The first conductive oxide film 4a and the first conductive member 5a can be formed by, for example, a known technique such as a sputtering method or a vapor deposition method.

In the first formation step, it is preferable to perform a surface roughening step of forming an uneven structure on the surface of the second semiconductor layer 13 before forming the first conductive oxide film 4a. Thereby, the light extraction efficiency of the manufactured light emitting device can be improved. In particular, this uneven structure scatters light traveling from the first light emitting section 1 to the second light emitting section, making it easier to take out the light from the fourth semiconductor layer 23 side of the second light emitting section 2. The surface of the second semiconductor layer 13 is roughened, for example, by wet etching. When the first conductive oxide film 4a is formed on the surface of the second semiconductor layer 13 after forming an uneven structure on the surface of the second semiconductor layer 13 by this roughening process, the first conductive oxide film 4a is An uneven structure along the uneven structure of the surface of the second semiconductor layer 13 is also formed on the surface. When forming the first conductive member 5a on the first conductive oxide film 4a on which the uneven structure is formed, the thickness of the first conductive member 5a is set such that the uneven structure of the first conductive oxide film 4a is covered. It is preferable to form the first conductive oxide film 4a thicker than the convex portion of the first conductive oxide film 4a. Thereby, in the bonding process to be described later, it is possible to reduce the possibility that bonding by the first conductive member 5a will be inhibited by the uneven structure of the first conductive oxide film 4a. The uneven structure has, for example, a plurality of protrusions having a height of 1 μm or more and 2 μm or less.

As the first conductive member 5a, metals such as indium, zinc, tin, indium tin, etc. can be used. The first conductive member 5a can also have a multilayer structure in which a plurality of metal layers are laminated. For example, it may have a multilayer structure in which an indium layer and a tin layer are laminated in order from the first conductive oxide film 4a side. Thereby, the first wafer 100 and the second wafer 200 can be stably bonded in the bonding process described later. When the first conductive member 5a has the multilayer structure described above, the thickness of each layer can be 0.1 nm or more and 5 nm or less. For example, when the first conductive member 5a has a multilayer structure in which an indium layer and a tin layer are laminated in order from the first conductive oxide film 4a side, the thickness of the indium layer is about 0.8 nm, and the thickness of the tin layer is about 0.8 nm. The film thickness can be made approximately 0.4 nm.

The thickness of the first conductive member 5a is preferably, for example, 1 nm or more and 10 nm or less. By setting the film thickness of the first conductive member 5a to 1 nm or more, it is easy to sufficiently oxidize the first conductive member 5a and improve the transmittance in the bonding process described later. By setting the film thickness of the first conductive member 5a to 10 nm or less, light absorption by the first conductive member 5a after the bonding process described later can be suppressed, and light extraction efficiency can be improved.

<Second formation step>
In the second formation step, a second conductive oxide film 4b electrically connected to the third semiconductor layer 21 is formed on the third semiconductor layer 21 of the second wafer 200. Further, a second conductive member 5b is formed on the second conductive oxide film 4b. As shown in FIG. 10, on the third semiconductor layer 21, a second conductive oxide film 4b and a second conductive member 5b are laminated. The second conductive oxide film 4b and the second conductive member 5b can be formed by, for example, a known technique such as a sputtering method or a vapor deposition method.

In the second formation step, it is preferable to perform a second roughening step of forming an uneven structure on the surface of the third semiconductor layer 21 before forming the second conductive oxide film 4b. Thereby, the light extraction efficiency of the manufactured light emitting device can be improved. In particular, the uneven structure scatters light traveling from the first light emitting section 1 to the second light emitting section 2, making it easier to take out the light from the fourth semiconductor layer 23 side of the second light emitting section 2. The surface of the third semiconductor layer 21 is roughened, for example, by wet etching. When the second conductive oxide film 4b is formed on the surface of the third semiconductor layer 21 after forming the uneven structure on the surface of the third semiconductor layer 21 by the second roughening step, the second conductive oxide film 4b An uneven structure along the uneven structure on the surface of the third semiconductor layer 21 is also formed on the surface of the third semiconductor layer 21 . When forming the second conductive member 5b on the second conductive oxide film 4b on which the uneven structure is formed, the thickness of the second conductive member 5b is set such that the uneven structure of the second conductive oxide film 4b is covered. In other words, it is preferable to make it thicker than the convex portion of the second conductive oxide film 4b. Thereby, in the bonding process to be described later, it is possible to reduce the possibility that bonding by the second conductive member 5b will be inhibited by the uneven structure of the second conductive oxide film 4b. The uneven structure has, for example, a plurality of protrusions having a height of 1 μm or more and 2 μm or less.

As the second conductive member 5b, the same metal as the first conductive member 5a described above can be used. Further, like the first conductive member 5a, the second conductive member 5b can also have a multilayer structure in which a plurality of metal layers are laminated. For example, a multilayer structure may be formed in which an indium layer and a tin layer are laminated in order from the second conductive oxide film 4b side. Thereby, the first wafer 100 and the second wafer 200 can be stably bonded in the bonding process described later. When the second conductive member 5b has the multilayer structure described above, the thickness of each layer can be 0.1 nm or more and 5 nm or less. For example, when the second conductive member 5b has a multilayer structure in which an indium layer and a tin layer are laminated in order from the first conductive oxide film 4a side, the thickness of the indium layer is about 0.8 nm, and the thickness of the tin layer is about 0.8 nm. The film thickness can be made approximately 0.4 nm.

The thickness of the second conductive member 5b is preferably, for example, greater than or equal to 1 nm and less than or equal to 10 nm. By setting the film thickness of the second conductive member 5b to 1 nm or more, it is easy to sufficiently oxidize the second conductive member 5b and improve the transmittance in the bonding process described later. By setting the film thickness of the second conductive member 5b to 10 nm or less, light absorption by the second conductive member 5b can be suppressed and light extraction efficiency can be improved.

<Joining process>
As shown in FIG. 11, in the bonding step, the first conductive member 5a provided on the first conductive oxide film 4a and the second conductive member 5b provided on the second conductive oxide film 4b are bonded by thermocompression. Join by. Thereby, the first wafer 100 and the second wafer 200 are bonded. As shown in FIG. 12, a first light emitting section 1 and a second light emitting section 2 are provided on a first substrate 71. The thermocompression bonding in the bonding step is performed, for example, by applying pressure in a vacuum at a temperature of 250° C. or more and 550° C. or less for 60 minutes or more and 90 minutes or less.

The transmittance for the wavelength of light from the first active layer 12 of the first conductive member 5a and the second conductive member 5b after the bonding process is the same as that of the first conductive member in the first forming process and the second forming process described above. It is higher than the transmittance of the wavelength of light from the first active layer 12 of the first active layer 5a and the second conductive member 5b. That is, by performing the bonding process, the first conductive member 5a and the second conductive member 5b have higher transmittance for the wavelength of light from the first active layer 12 than before the bonding process. It is presumed that this is because a part of the metal film constituting the first conductive member 5a and the second conductive member 5b is oxidized by thermocompression bonding and changed into a metal oxide film. Ru. For example, by forming the first conductive member 5a and the second conductive member 5b with a multilayer structure in which an indium layer and a tin layer are laminated, and then performing a bonding process, the first conductive member 5a and the second conductive member 5b after the bonding process are A part of the second conductive member 5b changes to a member containing indium tin oxide (ITO).

Further, in this embodiment, the bonding process is performed with the first conductive member 5a and the second conductive member 5b in contact with the first conductive oxide film 4a and the second conductive oxide film 4b, respectively. Therefore, oxygen contained in the first conductive oxide film 4a and the second conductive oxide film 4b is supplied to the first conductive member 5a and the second conductive member 5b, and Oxidation of the metal film constituting the member 5b can be further promoted. Therefore, according to the present embodiment, the oxidation of the first conductive member 5a and the second conductive member 5b after the bonding process is promoted, and the transmittance for the wavelength of light from the first active layer 12 is efficiently increased. be able to.

When the first conductive member 5a and the second conductive member 5b are formed into a multilayer structure in which the above-described indium layer and tin layer are laminated, the joining process is performed, the first conductive member 5a and the second conductive member 5b are Thermocompression bonding is performed with the tin layers in contact. Therefore, in the bonding step, the tin layers of the first conductive member 5a and the second conductive member 5b are stably bonded to each other. As a result, while stably bonding the first wafer 100 and the second wafer 200, the transmittance of the first conductive member 5a and the second conductive member 5b with respect to the wavelength of light from the first active layer 12 can be adjusted during the bonding process. can be higher than before.

<Exposure process>
After the bonding process, the second substrate 72 of the second wafer 200 shown in FIG. 11 is removed, and the fourth semiconductor layer 23 is exposed as shown in FIG. 12. The second substrate 72 can be removed by laser lift-off or wet etching, similar to the method for removing the third substrate 73 described above. By using a silicon substrate for the second substrate 72, the second substrate 72 can be easily removed in the same manner as the third substrate 73 described above.

<First electrode formation process>
As shown in FIG. 13, in the first electrode 31 forming step, the first electrode 31 in a predetermined pattern is formed on the fourth semiconductor layer 23 of the second light emitting section 2. As shown in FIG. For example, the first electrode 31 is formed on the upper surface of the fourth semiconductor layer 23 at a position avoiding a cutting position CL, which will be described later. The first electrode 31 is formed, for example, by a lift-off method using photoresist. For example, a photoresist is formed on a portion of the fourth semiconductor layer 23 where the first electrode 31 is not formed, and a metal film is formed on the fourth semiconductor layer 23 and the photoresist using the photoresist as a mask. The first electrode 31 can then be formed by removing the photoresist together with the metal film formed on the photoresist.

<Dividing process>
Finally, the wafer on which the first electrode 31 is formed is divided into individual light emitting devices of a desired size. This division is performed by dicing, for example along the cutting position CL shown in FIG. 13.

According to the method for manufacturing a light emitting device of the above embodiment, the transmittance of the wavelength of light from the active layer at the bonding portion is improved by the bonding process using the first conductive member 5a and the second conductive member 5b. At the same time, the first wafer 100 and the second wafer 200 can be bonded. Therefore, it is possible to easily manufacture a light emitting device that includes the first light emitting section 1 and the second light emitting section 2 and has improved light extraction efficiency. Moreover, it becomes possible to form the first electrode 31 and the second electrode 32 above and below the structure including the first light emitting part 1 and the second light emitting part 2. As a result, the formation range of the first active layer 12 and the second active layer 22 per unit area in the top view of the light emitting device can be increased, and a light emitting device with a large light emitting area can be easily manufactured.

Next, each component of the light emitting device of the embodiment will be explained.

<Substrate 7>
As the substrate 7, a substrate made of Si, CuW, Mo, etc. can be used. When using a substrate made of silicon as the substrate 7, it is preferable that the electrical resistance is low. For example, the resistance may be lowered by doping a substrate made of Si with boron or the like. Further, by using a silicon substrate as the substrate 7, the wafer can be easily cut in the cutting process described later, and productivity can be improved.

<First light emitting section 1, second light emitting section 2>
The first light emitting section 1 includes, in order from the substrate 7 side, a first semiconductor layer 11 of a first conductivity type, a first active layer 12, and a second semiconductor layer 13 of a second conductivity type different from the first conductivity type. ,including. Like the first light emitting part 1, the second light emitting part 2 includes, in order from the first light emitting part side, a third semiconductor layer 21 of the first conductivity type, a second active layer 22, and a fourth semiconductor layer of the second conductivity type. A semiconductor layer 23 is included. Here, the first conductivity type refers to one of the n-type and p-type conductivity type, and the second conductivity type refers to the other conductivity type. In this embodiment, the first conductivity type is p type, and the second conductivity type is n type.

Semiconductor materials constituting the first _light emitting section 1 and the second light emitting section 2 include _III -V group nitride semiconductors ( _In )) can be used.

The first semiconductor layer 11, the second semiconductor layer 13, the third semiconductor layer 21, and the fourth semiconductor layer 23 may each be composed of a single layer, or may be composed of a stacked structure including a plurality of layers. may have been done. Further, the first semiconductor layer 11 and the third semiconductor layer 21 may partially include a layer that is not of the first conductivity type, for example, an undoped semiconductor layer, and the second semiconductor layer 13 and the fourth semiconductor layer 23 may partially include a layer that is not of the second conductivity type, or an undoped semiconductor layer. Here, the undoped semiconductor layer refers to a layer that is grown without adding impurities of the first or second conductivity type during growth. It may contain impurities.

Further, the first active layer 12 and the second active layer 22 may have a single quantum well structure or a multiple quantum well structure. Further, the first active layer 12 and the second active layer 22 have substantially the same emission peak wavelength. The emission peak wavelengths of the first active layer 12 and the second active layer 22 are each, for example, 430 nm or more and 480 nm or less.

It is preferable that an uneven structure is formed on the upper surface of the second semiconductor layer 13 of the first light emitting section 1. As will be described later, the upper surface of the second semiconductor layer 13 is the interface with the first transparent conductive film 4a. This uneven structure allows light to be easily extracted from the first light emitting section 1 toward the second light emitting section 2. It is preferable that an uneven structure is formed on the lower surface of the third semiconductor layer 21 of the second light emitting section 2. This uneven structure allows light to be easily extracted from the first light emitting section 1 toward the second light emitting section 2.

<First conductive oxide film 4a, second conductive oxide film 4b>
The first conductive oxide film 4 a is provided on the upper surface of the second semiconductor layer 13 of the first light emitting section 1 . The second conductive oxide film 4b is provided on the lower surface of the third semiconductor layer 21 of the second light emitting section 2. The first conductive oxide film 4a functions as an electrode for making ohmic contact with the second semiconductor layer 13 of the first light emitting section 1. The second conductive oxide film 4b functions as an electrode for making ohmic contact with the third semiconductor layer 21 of the second light emitting section 2.

When forming the first conductive oxide film 4a on the surface of the second semiconductor layer 13 having an uneven structure, the surface of the first conductive oxide film 4a has an uneven structure along the uneven structure of the second semiconductor layer 13. Preferably, a structure is formed. Similarly, when forming the second conductive oxide film 4b on the surface of the third semiconductor layer 21 on which the uneven structure is formed, the uneven structure of the third semiconductor layer 21 is formed on the surface of the second conductive oxide film 4b. It is preferable that a concavo-convex structure along the surface is formed. Since the uneven structure is formed on the surfaces of the first conductive oxide film 4a and the second conductive oxide film 4b, the light directed from the first light emitting section 1 to the second light emitting section 2 can be directed to the first conductive oxide film 4b. It is scattered at the interface between 4a and conductive member 5, or at the interface between second conductive oxide film 4b and conductive member 5. Therefore, of the light traveling from the first light emitting section 1 to the second light emitting section 2, the light reflected toward the second light emitting section 1 side can be reduced, and the light extraction efficiency of the light emitting device can be improved. The uneven structure has, for example, a plurality of protrusions having a height of 1 μm or more and 2 μm or less.

The materials constituting the first conductive oxide film 4a and the second conductive oxide film 4b have high translucency and conductivity for light from the first active layer 12 and the second active layer 22. It is preferable to use For the first conductive oxide film 4a and the second conductive oxide film 4b, metal oxides such as indium tin oxide (ITO) and indium zinc oxide (IZO) can be used, for example. This suppresses absorption of light from the first light emitting section 1 and the second light emitting section 2 by the first conductive oxide film 4a and the second conductive oxide film 4b, improving the light extraction efficiency of the light emitting device. can be done.

The thickness of the first conductive oxide film 4a can be, for example, 10 nm or more and 1000 nm or less. The thickness of the second conductive oxide film 4b can be, for example, 10 nm or more and 1000 nm or less. By setting the film thickness of the first conductive oxide film 4a and the second conductive oxide film 4b to 10 nm or more, ohmic contact with the semiconductor layer can be easily ensured. By setting the thickness of the first conductive oxide film 4a and the second conductive oxide film 4b to 1000 nm or less, light absorption by the first conductive oxide film 4a and the second conductive oxide film 4b can be reduced. .

<Conductive member 5>
The conductive member 5 is provided between the first conductive oxide film 4a and the second conductive oxide film 4b, and electrically connects the first light emitting section 1 and the second light emitting section 2. The conductive member 5 is formed by joining a first conductive member 5a and a second conductive member 5b. Examples of materials constituting the conductive member 5 include indium, tin, and zinc, and alloys and oxides containing these metals as main components.

<Metal layer 6>
As the metal layer 6, a solder material mainly composed of AuSn, NiSn, AgSn, etc., or an alloy mainly composed of Au and Au, etc. can be used. It is preferable that the metal layer 6 includes a metal layer for improving adhesion to the member forming the metal layer 6. For example, it is preferable to include a metal layer made of Pt or Ti as an adhesion layer. In this embodiment, the thickness of the metal layer 6 can be changed as appropriate in consideration of bondability and conductivity.

<First electrode 31>
The first electrode 31 is provided on the upper surface of the fourth semiconductor layer 23 of the second light emitting section 2 . As the first electrode 31, a metal layer containing Au as a main component can be used. Further, in order to improve adhesion or prevent diffusion between metal layers, a multilayer structure may be used in which metal layers such as Ti, Pt, Ni, W, and Rh are laminated. The first electrode 31 can have, for example, a multilayer structure in which a Ti layer, a Pt layer, an Au layer, and a Ti layer are stacked in this order from the surface of the fourth semiconductor layer 23. The first electrode 31 can be formed, for example, by a known technique such as a sputtering method or a vapor deposition method.

<Second electrode 32>
The second electrode 32 is provided on the lower surface of the first semiconductor layer 11 of the first light emitting section 1 . As the second electrode 32, it is preferable to use a metal layer containing a metal that can reflect the wavelength of light from the first light emitting part 1. For example, a metal layer such as Ag, Al, etc., or a layer containing these metals as a main component is preferably used. It is preferable that the alloy contains the following alloys. Thereby, the light from the first light emitting section 1 and the second light emitting section 2 can be reflected toward the fourth semiconductor layer 23 side of the second light emitting section 2, so that the light extraction efficiency of the light emitting device can be improved. Further, in order to improve adhesion and the like, a multilayer structure including a metal layer made of Ni, Ti, Pt, etc. may be used. For example, a multilayer structure may be formed in which an Ag layer, a Ni layer, a Ti layer, and a Pt layer are stacked in this order from the surface of the first semiconductor layer 11. The second electrode 32 can be formed, for example, by a known technique such as a sputtering method or a vapor deposition method.

1 First light emitting part 2 Second light emitting part 4 Conductive oxide film 4a First conductive oxide film 4b Second conductive oxide film 5 Conductive member 5a First conductive member 5b Second conductive member 6 Metal layer 7 Substrate 71 first substrate 72 second substrate 73 third substrate 11 first semiconductor layer 12 first active layer 13 second semiconductor layer 21 third semiconductor layer 22 second active layer 23 fourth semiconductor layer 31 first electrode 32 second electrode 35 Insulating film 100 First wafer 200 Second wafer

Claims (5)

a first substrate, a first semiconductor layer of a first conductivity type, a first active layer, and a second semiconductor layer of a second conductivity type different from the first conductivity type on the first substrate; a first wafer preparation step of preparing first wafers including the first substrate in order from the first substrate side;
a second substrate, and on the second substrate, a fourth semiconductor layer of the second conductivity type, a second active layer, and a third semiconductor layer of the first conductivity type, in order from the second substrate side. a second wafer preparation step of preparing a second wafer containing the
a first conductive oxide film having a light-transmitting property and electrically connected to the second semiconductor layer on the second semiconductor layer exposed on the surface of the first wafer; a first conductive member having a multilayer structure in which an indium layer and a tin layer are laminated in order from the first conductive oxide film side;
a second conductive oxide film having a light-transmitting property and electrically connected to the third semiconductor layer on the third semiconductor layer of the second wafer; and a second conductive oxide film provided on the second conductive oxide film, a second forming step of forming a second conductive member having a multilayer structure in which an indium layer and a tin layer are laminated in order from the second conductive oxide film side;
a joining step of joining the first wafer and the second wafer by thermocompression bonding the first conductive member and the second conductive member;
After the bonding step, an exposing step of removing the second substrate of the second wafer and exposing the fourth semiconductor layer,
The transmittance for the wavelength of light from the first active layer of the first conductive member and the second conductive member after the bonding step is the same as that of the first conductive member in the first forming step and the second forming step. A method for manufacturing a light emitting device, wherein the transmittance of the conductive member and the second conductive member to the wavelength of light from the first active layer is higher than that of the first active layer. 2. The method of manufacturing a light emitting device according to claim 1, wherein in the first forming step, an uneven structure is formed on the surface of the second semiconductor layer before forming the first conductive oxide film. 3. The method of manufacturing a light emitting device according to claim 1, wherein in the second forming step, an uneven structure is formed on the surface of the third semiconductor layer before forming the second conductive oxide film. further comprising a first electrode forming step of forming a first electrode on the surface of the fourth semiconductor layer exposed in the exposing step,
2. A second electrode is formed between the first substrate and the first semiconductor layer in the first wafer preparation step, the second electrode electrically connecting the first substrate and the first semiconductor layer. 3. The method for manufacturing a light emitting device according to any one of 3. 5. The method for manufacturing a light emitting device according to claim 1, wherein the first conductive oxide film and the second conductive oxide film are formed of indium tin oxide.

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