Light-emitting diode structure

Abstract

To improve a yield of a metal junction process of a light-emitting diode structure, and enhance a light extraction efficiency.SOLUTION: The present invention relates to a light-emitting diode structure 1 comprising: a permanent substrate 10; a joint complex layer 20; a mirror reflection complex layer 30; and an epitaxial semiconductor complex layer 40. The joint complex layer is arranged onto the permanent substrate. The mirror reflection complex layer is arranged onto the joint complex layer. The epitaxial semiconductor complex layer is arranged onto the mirror reflection complex layer. A joint boundary surface of the joint metal complex layer and the permanent substrate is a non-flatness surface of which a front surface roughness is less than 0.5 micrometer (μm).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a light emitting diode structure, and more particularly to a high brightness light emitting diode structure. [Background technology]

[0002] Light Emitting Diode (LED) structure has advantages such as high brightness, small size, low power consumption, and long life, and is widely used in lighting and display products. In the manufacturing process of light emitting diodes, wafer bonding is a key step for bonding a single LED element to a carrier substrate. The purpose of this bonding process is to improve the performance of the LED element by increasing the light output efficiency and thermal management.

[0003] Specifically, LED elements that have undergone a semiconductor epitaxial process can be bonded to a permanent substrate by metal bonding to obtain more efficient light output. Optical components such as a mirror reflective layer can be installed on the substrate to enhance the light reflection effect and improve the light extraction efficiency. At the same time, when the LED element and the heat dissipation substrate are closely combined, the heat generated by the LED element can be effectively transferred to the outside through the heat dissipation substrate, maintaining the appropriate operating temperature of the LED element and improving the performance and lifespan of the LED element.

[0004] However, in the bonding process between the LED element and the permanent substrate, it may have an adverse effect on the mirror reflection system of the LED element, and thus may have an adverse effect on the performance of the LED. In the conventional metal bonding process, in order to ensure the reflection efficiency of the mirror reflection system of the LED element, it is necessary to flatten the bonding interface between the LED element and the permanent substrate. If this bonding interface is not flat, it will have an adverse effect on the flatness of the mirror reflection system of the LED element after bonding. As a result, the light emitted from the LED element will be scattered during the reflection process, and the reflection efficiency will decrease. Consequently, the light output efficiency decreases. To overcome the problems caused by the metal bonding process that adversely affects the light extraction efficiency of the LED element, it is an urgent issue for the industry to develop an innovative light-emitting diode structure that can improve the performance of the LED element while considering the bonding strength between the LED element and the permanent substrate.

Summary of the Invention

[0005] The main object of the present invention is to provide a high-brightness light-emitting diode structure. By adjusting the roughness of the bonding interface between the permanent substrate and the metal bonding layer, the effect of strengthening the metal bonding can be obtained without adversely affecting the reflection efficiency of the mirror reflection system. The present invention can improve the yield of the metal bonding process of the conventional light-emitting diode structure and increase the light extraction efficiency.

[0006] To achieve the above object, the present invention provides a light-emitting diode structure including a permanent substrate, a bonding metal composite layer, a mirror reflection composite layer, and an epitaxial semiconductor composite layer. The bonding metal composite layer is disposed on the permanent substrate. The mirror reflection composite layer is disposed on the bonding metal composite layer. The epitaxial semiconductor composite layer is disposed on the mirror reflection composite layer. The bonding interface between the bonding metal composite layer and the permanent substrate is a non-flat surface with a surface roughness (Ra) of less than 0.5 micrometers (μm).

[0007] In an embodiment of the present invention, the bonding metal composite layer has a first bonding metal layer and a second bonding metal layer, and the bonding interface between the first bonding metal layer and the second bonding metal layer is a flat surface.

[0008] In an embodiment of the present invention, the materials of the first bonding metal layer and the second bonding metal layer are one selected from the group consisting of gold (Au), indium (In), and tin (Sn), or a combination thereof.

[0009] In an embodiment of the present invention, the thicknesses of the first bonding metal layer and the second bonding metal layer are from about 1 micrometer (μm) to 2 micrometers (μm).

[0010] In an embodiment of the present invention, the bonding interface between the bonding metal composite layer and the permanent substrate is a patterned interface with a pattern depth of less than 0.5 micrometer (μm).

[0011] In an embodiment of the present invention, the mirror reflection composite layer has a first mirror reflection layer and a second mirror reflection layer, and the bonding interface between the first mirror reflection layer and the second mirror reflection layer is a flat surface.

[0012] In an embodiment of the present invention, the material of the first mirror reflection layer is one selected from the group consisting of titanium dioxide (TiO2), silicon nitride (SiN x ), silicon dioxide (SiO2), magnesium fluoride (MgF2), indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), and zinc oxide (ZnO), or a combination thereof.

[0013] In an embodiment of the present invention, the material of the second mirror reflection layer is one selected from the group consisting of silver (Ag), gold (Au), aluminum (Al), platinum (Pt), titanium (Ti), and nickel (Ni), or a combination thereof.

[0014] To achieve the above object, the present invention further provides a light-emitting diode structure including a permanent substrate, a bonding metal composite layer, a mirror reflection composite layer, and an epitaxial semiconductor composite layer. The bonding metal composite layer is disposed on the permanent substrate. The mirror reflection composite layer is disposed on the bonding metal composite layer. The epitaxial semiconductor composite layer is disposed on the mirror reflection composite layer. The bonding interface between the mirror reflection composite layer and the epitaxial semiconductor composite layer is a non-flat surface. The mirror reflection composite layer has a first mirror reflection layer and a second mirror reflection layer. The bonding interface between the first mirror reflection layer and the second mirror reflection layer is a flat surface.

[0015] Those skilled in the art can understand other objects of the present invention, as well as the technical means and embodiments of the present invention, by referring to the drawings and the embodiments described below.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0017] Hereinafter, the content of the present invention will be described through examples. It should be noted that the examples of the present invention are examples of the embodiments, and are not intended to be limited to the environments, applications, or specific aspects as described in the examples. Therefore, the description of the examples is for explaining the present invention, but does not limit the present invention. In the embodiments and the drawings, components not directly related to the present invention are omitted and not shown. The dimensional relationships of the components in the drawings are for facilitating understanding and do not limit the actual dimensions.

[0018] Figure 1 shows an embodiment of a light-emitting diode structure according to the present invention. The light-emitting diode structure 1 includes a permanent substrate 10, a bonding metal composite layer 20, a mirror reflection composite layer 30, an epitaxial semiconductor composite layer 40, and an electrode 50. The bonding metal composite layer 20 is disposed on the permanent substrate 10. The mirror reflection composite layer 30 is disposed on the bonding metal composite layer 20. The epitaxial semiconductor composite layer 40 is disposed on the mirror reflection composite layer 30. The electrode 50 is disposed on the epitaxial semiconductor composite layer 40. First, it should be noted that the light-emitting diode structure of the present invention shown in Figure 1 is the final structure in which the epitaxial composite layer subjected to the epitaxial process is transferred from the temporary epitaxial growth substrate to the permanent substrate using the innovative technology of the present invention. Hereinafter, the present invention will be described in detail based on several embodiments.

[0019] Specifically, the permanent substrate 10 of the light-emitting diode structure 1 of the present invention may be a silicon substrate or a sapphire substrate, but is not limited thereto. An appropriate substrate can be selected according to the actual use and the characteristics of the process. For example, a silicon substrate has high mechanical structural support strength and contributes to the stability in the manufacturing process. Also, a silicon substrate has higher heat dissipation than a sapphire substrate and is useful for temperature control of the LED element. Note that the cost of the silicon substrate is lower than that of the sapphire substrate, which is an important factor in industrial mass production. On the other hand, a sapphire substrate has high transparency to blue light and ultraviolet light and is useful for improving the light output efficiency of the LED element. Also, a sapphire substrate has high stability in a high-temperature environment, which is important for high-power LED elements. Note that since sapphire is a better insulator, it can prevent the intrusion of current and improve the insulation performance of the component.

[0020] Also, in an embodiment of the light-emitting diode structure of the present invention, the epitaxial semiconductor composite layer 40 on the permanent substrate 10 may be an aluminum gallium indium arsenide (AlGaInAs) double hetero structure, but is not limited thereto. This epitaxial semiconductor composite layer 40 is formed by epitaxial lamination on an epitaxial growth substrate (not shown), for example, an indium phosphide (InP) substrate. Specifically, in this embodiment, the double hetero structure of the epitaxial semiconductor composite layer 40 includes a P-type epitaxial semiconductor layer 42, a light-emitting layer 44, and an N-type epitaxial semiconductor layer 46. The P-type epitaxial semiconductor layer 42 is a cladding layer of aluminum gallium arsenide (AlGaAs) doped with carbon (C). The light-emitting layer 44 is formed in a multiple quantum well (MQW) structure, includes aluminum gallium arsenide (AlGaAs) as a barrier layer of the multiple quantum well, and includes indium gallium arsenide (InGaAs) as a well layer of the quantum well. Also, the N-type epitaxial semiconductor layer 46 is a cladding layer of aluminum gallium arsenide (AlGaAs) doped with silicon (Si). Note that the materials described in the above embodiment are examples, and the present invention is not limited thereto. In practice, the material and composition can be adjusted according to the emission wavelength. For example, the epitaxial layer may be aluminum gallium indium phosphide (AlGaInP), indium gallium phosphide (InGaP), aluminum gallium arsenide (AlGaAs), indium gallium arsenide (InGaAs), indium phosphide (InP), or the like.

[0021] Also, in this embodiment, the mirror reflection composite layer 30 has a first mirror reflection layer 32 and a second mirror reflection layer 34. The first mirror reflection layer 32 may be composed of a low refractive index dielectric material, but is not limited thereto. The low refractive index dielectric material is titanium dioxide (TiO2), silicon nitride (SiN x) One selected from the group consisting of silicon dioxide (SiO2), magnesium fluoride (MgF2), indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), and zinc oxide (ZnO), or a combination thereof. The second mirror reflection layer 34 may be composed of a metal material with high reflectivity, but is not limited thereto. The metal material with high reflectivity is one selected from the group consisting of silver (Ag), gold (Au), aluminum (Al), platinum (Pt), titanium (Ti), and nickel (Ni), or a combination thereof.

[0022] In an embodiment of the present invention, considering the support strength and heat dissipation efficiency of the light-emitting diode structure, after transferring the epitaxial semiconductor composite layer 40 in the light-emitting diode structure from the original epitaxial growth substrate to the permanent substrate 10, which is the silicon substrate, by metal bonding, it is necessary to remove the original epitaxial growth substrate. Therefore, the first bonding metal layer 22 must first be formed on the permanent substrate 10 by metal evaporation before the metal bonding process. Next, the second bonding metal layer 24 is formed by evaporation on the mirror reflection composite layer 30 of the original epitaxial growth substrate. The materials of the first bonding metal layer 22 and the second bonding metal layer 24 are one selected from the group consisting of gold (Au), indium (In), and tin (Sn), or a combination thereof. Note that the thicknesses of the first bonding metal layer 22 and the second bonding metal layer 24 are from about 1 micrometer (μm) to 2 micrometers (μm).

[0023] As disclosed in the above-mentioned background art, in the present invention, when performing metal bonding on a permanent substrate, similarly, it is necessary to flatten the bonding interface between the first bonding metal layer 22 and the second bonding metal layer 24. Thereby, the reflection efficiency of the mirror reflection system can be ensured, and a decrease in reflection efficiency due to unevenness of the bonding interface can be avoided. However, on the other hand, in order to increase the bonding strength of the bonding interface between the first bonding metal layer 22 and the second bonding metal layer 24 and improve the process yield of metal bonding, in the present invention, the bonding interface between the permanent substrate 10 and the first bonding metal layer 22 is made into a non-planar surface. This non-planar surface can achieve the purpose of increasing the bonding area, enhancing the bonding strength, and improving the yield of the metal bonding process. Thereby, the epitaxial semiconductor structure can be smoothly transferred to the permanent substrate. However, in order to avoid excessive "roughness" of the bonding interface, there is an upper limit to the non-planarity between the permanent substrate 10 and the first bonding metal layer 22. In the case of excessive "roughness", when performing metal bonding between the first and second bonding metal layers 22 and 24, the unevenness of the bonding interface between the permanent substrate 10 and the first bonding metal layer 22 of the bonding metal composite layer will indirectly affect the flatness of the mirror reflection composite layer 30, and the reflection efficiency of light rays will decrease. Specifically, according to the research of the present invention, the roughness Ra value of the non-planar bonding interface between the permanent substrate 10 and the first bonding metal layer 22 must be less than 0.5 micrometers (μm). In this way, while ensuring the flatness of the mirror reflection composite layer 30, the bonding strength of the two bonding metal layers can be improved.

[0024] In another embodiment of the present invention, the bonding interface between the bonding metal composite layer and the permanent substrate is made into a non-planar surface by patterning treatment. As shown in FIG. 2, specifically, by performing patterning treatment, a patterned interface is formed between the first bonding metal layer 22 and the permanent substrate 10. The pattern depth of this patterned interface must also be less than 0.5 micrometers (μm). In this way, while improving the bonding strength between the two bonding metal layers, the flatness of the mirror reflection composite layer 30 can be ensured, and a decrease in the reflection efficiency of the mirror reflection layer can be avoided.

[0025] After an epitaxial growth process is performed on an epitaxial growth substrate, it should be noted that the surface of the epitaxial semiconductor composite layer 40 usually becomes a non-flat surface with irregularities. Therefore, if a coating process of a mirror reflection layer is then carried out on the epitaxial semiconductor composite layer 40, the first mirror reflection layer 32 of the mirror reflection composite layer 30 is also usually formed on the epitaxial semiconductor composite layer 40 in a non-flat state. In this case, the bonding interface between the first mirror reflection layer 32 of the mirror reflection composite layer 30 and the epitaxial semiconductor composite layer 40 also becomes a non-flat surface. In this case, if the metal coating process of the second mirror reflection layer 34 of the mirror reflection composite layer 30 is carried out as it is, the bonding interface between the first mirror reflection layer 32 and the second mirror reflection layer 34 becomes a non-flat surface. This non-flat surface reduces the reflection efficiency of light from the light-emitting diode and reduces the light extraction efficiency of the light-emitting diode. In view of the above circumstances, in the present invention, in order to avoid the above problems, as shown in FIG. 3, after the coating process of the first mirror reflection layer 32 is carried out and before the coating process of the second mirror reflection layer 34 is carried out, a polishing process is carried out. Thereby, the coating process of the second mirror reflection layer 34 is carried out after the irregularities on the surface of the first mirror reflection layer 32 are improved. As a result, after the mirror coating process, the bonding interface between the first mirror reflection layer 32 and the second mirror reflection layer 34 in the mirror reflection composite layer 30 of the present invention becomes a flat interface, so that the reflection efficiency of the mirror system is improved and the light extraction efficiency of the light-emitting diode is improved.

[0026] The above embodiments illustrate the embodiments of the present invention and illustrate the characteristic configurations of the present invention. The present invention is not limited to the above embodiments. Modifications or equivalent arrangements that can be easily made by those skilled in the art are also within the scope of the present invention. The scope of protection of the rights of the present invention shall be based on the scope of the claims.

Description of reference numerals

[0027] 1 Light-emitting diode structure 10 Permanent substrate 20 Bonding metal composite layer 22 First bonding metal layer 24 Second bonding metal layer 30 Mirror reflection composite layer 32 First mirror reflection layer 34 Second mirror reflection layer 40 Epitaxial semiconductor composite layer 42 P-type epitaxial semiconductor layer 44 Light-emitting layer 46 N-type epitaxial semiconductor layer 50 Electrode

Claims

1. A light-emitting diode structure, comprising: a permanent substrate; a bonding metal composite layer disposed on the permanent substrate; a mirror reflection composite layer disposed on the bonding metal composite layer; an epitaxial semiconductor composite layer disposed on the mirror reflection composite layer, wherein a bonding interface between the bonding metal composite layer and the permanent substrate is a non-planar surface with a surface roughness (Ra) of less than 0.5 micrometers (μm).

2. The light-emitting diode structure according to claim 1, wherein the bonding metal composite layer has a first bonding metal layer and a second bonding metal layer, and a bonding interface between the first bonding metal layer and the second bonding metal layer is a planar surface.

3. The light-emitting diode structure according to claim 2, wherein a material of the first bonding metal layer and the second bonding metal layer is one selected from the group consisting of gold (Au), indium (In), and tin (Sn), or a combination thereof.

4. The light-emitting diode structure according to claim 2, wherein a thickness of the first bonding metal layer and the second bonding metal layer is from about 1 micrometer (μm) to 2 micrometers (μm).

5. The light-emitting diode structure according to claim 1, wherein the bonding interface between the bonding metal composite layer and the permanent substrate is a patterned interface with a pattern depth of less than 0.5 micrometers (μm).

6. The light-emitting diode structure according to claim 1, wherein the mirror reflection composite layer has a first mirror reflection layer and a second mirror reflection layer, and a bonding interface between the first mirror reflection layer and the second mirror reflection layer is a planar surface.

7. The material of the first mirror reflective layer is titanium dioxide (TiO ２ ), silicon nitride (SiN ｘ ), silicon dioxide (SiO ２ ), magnesium fluoride (MgF ２ ), indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), zinc oxide (ZnO), or a combination thereof, and the light emitting diode structure according to claim 6 is characterized in that it is one selected from the group consisting of

8. The light-emitting diode structure according to claim 6, wherein a material of the second mirror reflection layer is one selected from the group consisting of silver (Ag), gold (Au), aluminum (Al), platinum (Pt), titanium (Ti), and nickel (Ni), or a combination thereof.

9. A light-emitting diode structure, comprising: a permanent substrate; a bonding metal composite layer disposed on the permanent substrate; a mirror reflection composite layer disposed on the bonding metal composite layer; an epitaxial semiconductor composite layer disposed on the mirror reflection composite layer, wherein a bonding interface between the mirror reflection composite layer and the epitaxial semiconductor composite layer is a non-planar surface. The mirror reflection composite layer has a first mirror reflection layer and a second mirror reflection layer, and the bonding interface between the first mirror reflection layer and the second mirror reflection layer is a flat surface. A light-emitting diode structure.

10. The material of the first mirror reflective layer is titanium dioxide (TiO ２ ), silicon nitride (SiN ｘ ), silicon dioxide (SiO ２ ), magnesium fluoride (MgF ２ ), indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), zinc oxide (ZnO), or a combination thereof, and the light-emitting diode structure according to claim 9 is characterized in that it is one selected from the group consisting of or a combination thereof.

11. The material of the second mirror reflection layer is one selected from the group consisting of silver (Ag), gold (Au), aluminum (Al), platinum (Pt), titanium (Ti), nickel (Ni), or a combination thereof. The light-emitting diode structure according to claim 9, characterized in that.

12. The bonding interface between the bonding metal composite layer and the permanent substrate is a non-flat surface with a surface roughness (Ra) of less than 0.5 micrometers (μm). The light-emitting diode structure according to claim 9, characterized in that.

13. The bonding metal composite layer has a first bonding metal layer and a second bonding metal layer, and the bonding interface between the first bonding metal layer and the second bonding metal layer is a flat surface. The light-emitting diode structure according to claim 12, characterized in that.

14. The materials of the first bonding metal layer and the second bonding metal layer are one selected from the group consisting of gold (Au), indium (In), tin (Sn), or a combination thereof. The light-emitting diode structure according to claim 13, characterized in that.

15. The thicknesses of the first bonding metal layer and the second bonding metal layer are from about 1 micrometer (μm) to 2 micrometers (μm). The light-emitting diode structure according to claim 13, characterized in that.

16. The bonding interface between the bonding metal composite layer and the permanent substrate is a patterned interface with a pattern depth of less than 0.5 micrometers (μm). The light-emitting diode structure according to claim 9, characterized in that.

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