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) structures have advantages such as high brightness, small size, low power consumption, and long life, and are 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 LED elements by increasing light output efficiency and thermal management.

[0003] Specifically, LED elements that have undergone the semiconductor epitaxial process are bonded to a permanent substrate using metal bonding to achieve 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 light extraction efficiency. At the same time, when the LED element is tightly coupled with the heat dissipation substrate, the heat generated by the LED element can be effectively transferred to the outside through the heat dissipation substrate, maintaining the LED element at an appropriate operating temperature and improving the performance and lifespan of the LED element.

[0004] However, the bonding process between the LED element and the permanent substrate can adversely affect the mirror reflection system of the LED element, ultimately negatively impacting LED performance. In conventional metal bonding processes, the bonding interface between the LED element and the permanent substrate must be flat to ensure the reflective efficiency of the LED element's mirror reflection system. If this bonding interface is not flat, the flatness of the mirror reflection system of the LED element after bonding will be adversely affected. As a result, the light emitted from the LED element will be scattered during the reflection process, reducing its reflective efficiency. As a result, the light output efficiency will decrease. To overcome the problems caused by the metal bonding process that adversely affect the light extraction efficiency of LED elements, the industry is urgently seeking to develop innovative light-emitting diode structures that can improve LED element performance while taking into account the bonding strength between the LED element and the permanent substrate. Summary of the Invention

[0005] The primary objective 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 achieved without adversely affecting the reflective efficiency of the mirror reflection system. The present invention can improve the yield of the metal bonding process of conventional light-emitting diode structures 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 bonded metal composite layer, a mirror-reflective composite layer, and an epitaxial semiconductor composite layer. The bonded metal composite layer is disposed on the permanent substrate. The mirror-reflective composite layer is disposed on the bonded metal composite layer. The epitaxial semiconductor composite layer is disposed on the mirror-reflective composite layer. The bonded interface between the bonded 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 bonded 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 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.

[0009] In an embodiment of the present invention, the thickness of the first and second bonding metal layers is about 1 to 2 micrometers (μm).

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

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

[0012] In an embodiment of the present invention, the material of the first mirror reflective layer is 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), zinc oxide (ZnO), or a combination thereof.

[0013] In an embodiment of the present invention, the material of the second mirror reflective 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-reflective composite layer, and an epitaxial semiconductor composite layer. The bonding metal composite layer is disposed on the permanent substrate. The mirror-reflective composite layer is disposed on the bonding metal composite layer. The epitaxial semiconductor composite layer is disposed on the mirror-reflective composite layer. The bonding interface between the mirror-reflective composite layer and the epitaxial semiconductor composite layer is a non-flat surface. The mirror-reflective composite layer has a first mirror-reflective layer and a second mirror-reflective layer. The bonding interface between the first mirror-reflective layer and the second mirror-reflective 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 explanation of the drawings]

[0016] [Figure 1] 1 is a schematic diagram illustrating a light-emitting diode structure according to an embodiment of the present invention; [Figure 2] 1 is a schematic diagram illustrating a light-emitting diode structure according to another embodiment of the present invention; [Figure 3] 1 is a schematic diagram illustrating a light-emitting diode structure according to another embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described below through examples. Note that the examples of the present invention are merely examples of embodiments and are not intended to limit the present invention to the environments, applications, or specific aspects described in the examples. Therefore, the explanation of the examples is intended to explain the present invention, but does not limit the present invention. Note that components not directly related to the present invention are omitted and not shown in the embodiments and drawings. The dimensional relationships between the components in the drawings are intended to facilitate understanding and do not limit the actual dimensions.

[0018] FIG. 1 shows one 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-reflective 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-reflective composite layer 30 is disposed on the bonding metal composite layer 20. The epitaxial semiconductor composite layer 40 is disposed on the mirror-reflective 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 according to the present invention shown in FIG. 1 is a final structure in which an epitaxial composite layer that has undergone an epitaxial process is transferred from a temporary epitaxial growth substrate to a permanent substrate using the innovative technique of the present invention. The present invention will now 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, but is not limited to, a silicon substrate or a sapphire substrate. An appropriate substrate can be selected depending on the actual application and process characteristics. For example, a silicon substrate has high mechanical structural support strength, contributing to stability during the manufacturing process. Furthermore, a silicon substrate has better heat dissipation than a sapphire substrate, which helps control the temperature of the LED element. Furthermore, the cost of a silicon substrate is lower than that of a sapphire substrate, which is an important factor for industrial mass production. On the other hand, a sapphire substrate has high transparency to blue light and ultraviolet light, which helps improve the light output efficiency of the LED element. Furthermore, a sapphire substrate has high stability in high-temperature environments, which is important for high-power LED elements. Furthermore, sapphire is a better insulator, preventing current intrusion and improving the insulation performance of components.

[0020] In addition, 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, but is not limited to, an aluminum gallium indium arsenide (AlGaInAs) double heterostructure. 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 heterostructure of the epitaxial semiconductor composite layer 40 has 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 has a multiple quantum well (MQW) structure, containing aluminum gallium arsenide (AlGaAs) as the barrier layer of the multiple quantum well and indium gallium arsenide (InGaAs) as the well layer of the quantum well. The N-type epitaxial semiconductor layer 46 is a cladding layer of aluminum gallium arsenide (AlGaAs) doped with silicon (Si). The materials described in the above embodiment are merely examples, and the present invention is not limited thereto. In practice, the material and composition can be adjusted depending on 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] In this embodiment, the mirror-reflective composite layer 30 includes a first mirror-reflective layer 32 and a second mirror-reflective layer 34. The first mirror-reflective layer 32 may be made of a low-refractive index dielectric material, but is not limited to this. Examples of low-refractive index dielectric materials include titanium dioxide (TiO2), silicon nitride (SiN xThe second mirror reflective layer 34 may be made of, but is not limited to, a metal material having high reflectivity. The metal material having high reflectivity may be 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, in consideration of the support strength and heat dissipation efficiency of the LED structure, the epitaxial semiconductor composite layer 40 in the LED structure must be transferred from the original epitaxial growth substrate to the permanent substrate 10, which is the silicon substrate, by metal bonding, and then the original epitaxial growth substrate must be removed. Therefore, before the metal bonding process, the first bonding metal layer 22 must first be formed on the permanent substrate 10 by metal evaporation. Next, the second bonding metal layer 24 is formed on the mirror-reflective composite layer 30 of the original epitaxial growth substrate by evaporation. The materials for 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. The thicknesses of the first bonding metal layer 22 and the second bonding metal layer 24 are approximately 1 to 2 micrometers (μm).

[0023] As disclosed in the background art above, in the present invention, when metal bonding of a permanent substrate is performed, it is necessary to flatten the bonding interface between the first bonding metal layer 22 and the second bonding metal layer 24. This ensures the reflection efficiency of the mirror reflection system and prevents a decrease in reflection efficiency due to unevenness at the bonding interface. However, to increase the bonding strength at the bonding interface between the first bonding metal layer 22 and the second bonding metal layer 24 and improve the process yield of the metal bonding, the present invention provides an uneven surface at the bonding interface between the permanent substrate 10 and the first bonding metal layer 22. This uneven surface increases the bonding area, increases the bonding strength, and improves the yield of the metal bonding process. This allows the epitaxial semiconductor structure to be smoothly transferred to the permanent substrate. However, to avoid excessive "roughness" at the bonding interface, there is an upper limit to the unevenness between the permanent substrate 10 and the first bonding metal layer 22. In the case of excessive "roughness," when metal bonding is performed between the first and second bonding metal layers 22, 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 indirectly affects the flatness of the mirror-reflective composite layer 30, resulting in a decrease in the light reflection efficiency. Specifically, according to the research of the present invention, the roughness Ra value of the non-flat 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, the bonding strength of the two bonding metal layers can be improved while ensuring the flatness of the mirror-reflective composite layer 30.

[0024] In another embodiment of the present invention, the bonding interface between the bonding metal composite layer and the permanent substrate is made uneven by a patterning process. Specifically, as shown in FIG. 2, a patterned interface is formed between the first bonding metal layer 22 and the permanent substrate 10 by a patterning process. The pattern depth of this patterned interface must also be less than 0.5 micrometers (μm). In this way, the bonding strength between the two bonding metal layers can be improved while ensuring the flatness of the mirror-reflective composite layer 30 and avoiding a decrease in the reflective efficiency of the mirror-reflective layer.

[0025] It should be noted that after the epitaxial growth process is performed on the epitaxial growth substrate, the surface of the epitaxial semiconductor composite layer 40 usually has unevenness and is non-planar. Therefore, when a mirror-reflective layer coating process is subsequently performed on the epitaxial semiconductor composite layer 40, the first mirror-reflective layer 32 of the mirror-reflective composite layer 30 is also usually formed on the epitaxial semiconductor composite layer 40 in an uneven state. In this case, the junction interface between the first mirror-reflective layer 32 of the mirror-reflective composite layer 30 and the epitaxial semiconductor composite layer 40 also has an uneven surface. In this case, if a metal coating process is performed on the second mirror-reflective layer 34 of the mirror-reflective composite layer 30 without any further processing, the junction interface between the first mirror-reflective layer 32 and the second mirror-reflective layer 34 will have an uneven surface. This uneven 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 order to avoid the above problems, in the present invention, as shown in Fig. 3, a polishing step is performed after the coating step of the first mirror reflective layer 32 is performed and before the coating step of the second mirror reflective layer 34 is performed. In this way, the coating step of the second mirror reflective layer 34 is performed after the surface irregularities of the first mirror reflective layer 32 have been improved. As a result, after the mirror coating step, the bonding interface between the first mirror reflective layer 32 and the second mirror reflective layer 34 in the mirror reflective composite layer 30 of the present invention becomes a flat interface, thereby improving the reflection efficiency of the mirror system and the light extraction efficiency of the light emitting diode.

[0026] The above examples are intended to explain embodiments of the present invention and to explain the characteristic configurations of the present invention. The present invention is not limited to the above examples. 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 is based on the claims. [Explanation of symbols]

[0027] 1. Light-emitting diode structure 10 Permanent substrate 20 Bonded metal composite layer 22 First bonding metal layer 24 Second bonding metal layer 30 Mirror Reflective Composite Layer 32 First mirror reflective layer 34 Second mirror reflective layer 40 Epitaxial semiconductor composite layer 42 P-type epitaxial semiconductor layer 44 Light-emitting layer 46 N-type epitaxial semiconductor layer 50 electrodes

Claims

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

2. 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 the bonding interface between the first bonding metal layer and the second bonding metal layer is a flat surface.

3. 3. The light-emitting diode structure of claim 2, wherein the 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. 3. The light-emitting diode structure of claim 2, wherein the thickness of the first bonding metal layer and the second bonding metal layer is about 1 to 2 micrometers (μm).

5. 2. The light-emitting diode structure according to claim 1, wherein the mirror-reflective composite layer comprises a first mirror-reflective layer and a second mirror-reflective layer, and the bonding interface between the first mirror-reflective layer and the second mirror-reflective layer is a flat surface.

6. 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 6. The light-emitting diode structure of claim 5, wherein the material is one selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), zinc oxide (ZnO), or a combination thereof.

7. 6. The light-emitting diode structure of claim 5, wherein the material of the second mirror reflective 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.

8. 1. A light emitting diode structure, comprising: a permanent insulating substrate; a bonded metal composite layer disposed on the permanent insulating substrate; a mirror-reflective composite layer disposed on the bonded metal composite layer; an epitaxial semiconductor composite layer disposed on the mirror-reflective composite layer; a non-flat bonded interface is formed between the bonded metal composite layer and the permanent insulating substrate; a bonding interface between the mirror-reflecting composite layer and the epitaxial semiconductor composite layer is an uneven surface; The light-emitting diode structure, wherein the mirror-reflective composite layer includes a first mirror-reflective layer and a second mirror-reflective layer, and the bonding interface between the first mirror-reflective layer and the second mirror-reflective layer is a flat surface.

9. 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 9. The light-emitting diode structure of claim 8, wherein the material is one selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), zinc oxide (ZnO), or a combination thereof.

10. 9. The light-emitting diode structure of claim 8, wherein the material of the second mirror reflective 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.

11. 9. The light-emitting diode structure of claim 8, wherein the bonding interface between the bonding metal composite layer and the permanent insulating substrate is a non-flat surface with a surface roughness (Ra) of less than 0.5 micrometers (μm).

12. 12. The light-emitting diode structure according to claim 11, wherein 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.

13. 13. The light-emitting diode structure of claim 12, wherein the 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.

14. 13. The light emitting diode structure of claim 12, wherein the thickness of the first bonding metal layer and the second bonding metal layer is about 1 to 2 micrometers (μm).

15. 9. The light-emitting diode structure of claim 8, wherein the bonding interface between the bonding metal composite layer and the permanent insulating substrate is a patterned interface with a pattern depth of less than 0.5 micrometers (μm).

Images