Light emitting diode structure

Abstract

The invention relates to a light emitting diode structure which comprises a permanent substrate, a bonding metal composite layer, a specular reflection composite layer and an epitaxial semiconductor composite layer. Wherein the bonding metal composite layer is located on the permanent substrate, the specular reflection composite layer is located on the bonding metal composite layer, and the epitaxial semiconductor composite layer is located on the specular reflection composite layer. An uneven joint surface is arranged between the bonding metal composite layer and the permanent substrate, and the surface roughness (Ra) of the uneven joint surface is less than 0.5 micron (mu m).

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 Art

[0002] A light-emitting diode structure (LED for short) has the advantages of high brightness, small size, low power consumption, and long lifespan, and is widely used in lighting or display products. Chip bonding in the light-emitting diode manufacturing process is a key step, mainly for bonding a single LED chip to a carrier substrate. The purpose of this bonding process is to improve the light output efficiency and heat dissipation management to enhance the performance of the LED chip.

[0003] Specifically, by fixing the LED chip that has completed the semiconductor epitaxial process to a permanent substrate in a metal bonding manner, the output of light can be managed more effectively. The substrate may include some optical elements, such as a mirror reflection layer, which helps to improve the reflection effect of light and increase the light extraction output efficiency. At the same time, by bonding with a substrate having good scattering performance, after the LED chip is closely combined with the heat dissipation substrate, it helps to effectively transfer the heat generated by the LED chip to the outside through the heat dissipation substrate, thereby maintaining the appropriate working temperature of the LED chip and improving the performance and lifespan of the LED chip.

[0004] However, during the bonding process between the LED chip and the permanent substrate, it may affect the mirror reflection system on the LED chip, thereby affecting the performance of the LED. In the current existing metal bonding process, to ensure the reflection efficiency of the mirror reflection system of the LED chip, it is necessary to ensure that the bonding surfaces of both the LED chip and the permanent substrate are flat. If this bonding surface is not flat, after the bonding process, the flatness of the mirror reflection system of the LED chip will also be affected, ultimately resulting in scattering of the light generated by the subsequent LED chip during the reflection process, reducing the reflection efficiency, and finally reducing the light extraction efficiency. To overcome the problem that the metal bonding process affects the light extraction of the LED chip, the industry urgently needs an innovative light-emitting diode structure that can balance the bonding strength between the LED chip and the permanent substrate and improve the performance of the LED chip. Summary of the Invention

[0005] The main objective of the present invention is to provide a high-brightness light-emitting diode structure. By adjusting the roughness of the plane between the permanent substrate and the metal bonding layer, both the metal bonding strength can be enhanced and the reflection efficiency of the mirror reflection system is not affected, thereby improving the yield of the metal bonding process of the existing light-emitting diode structure and enhancing the light extraction efficiency.

[0006] To achieve the above object, the present invention provides a light-emitting diode structure, which includes a permanent substrate, a bonding metal composite layer, a mirror reflection composite layer, and an epitaxial semiconductor composite layer. Among them, the bonding metal composite layer is located on the permanent substrate, the mirror reflection composite layer is located on the bonding metal composite layer, and the epitaxial semiconductor composite layer is located on the mirror reflection composite layer. There is an uneven interface between the bonding metal composite layer and the permanent substrate, and the surface roughness (Ra) of the uneven interface is less than 0.5 micrometers (μm).

[0007] In an embodiment of the light-emitting diode structure of the present invention, the bonding metal composite layer includes a first bonding metal layer and a second bonding metal layer, and there is a flat interface between the first bonding metal layer and the second bonding metal layer.

[0008] In an embodiment of the light-emitting diode structure of the present invention, the materials of the first bonding metal layer and the second bonding metal layer are selected from one of the group consisting of gold (Au), indium (In), tin (Sn) and their combinations.

[0009] In an embodiment of the light-emitting diode structure of the present invention, the thickness of the first bonding metal layer and the second bonding metal layer is 1 micrometer (μm) to 2 micrometers (μm).

[0010] In an embodiment of the light-emitting diode structure of the present invention, there is a patterned interface between the bonding metal composite layer and the permanent substrate, and the pattern depth value of the patterned interface is less than 0.5 micrometers (μm).

[0011] In an embodiment of the light-emitting diode structure of the present invention, the mirror reflection composite layer includes a first mirror reflection layer and a second mirror reflection layer, and there is a flat interface between the first mirror reflection layer and the second mirror reflection layer.

[0012] In an embodiment of the light-emitting diode structure of the present invention, the material of the first mirror reflection layer is selected from one of the group consisting of titanium dioxide (TiO2), silicon nitride (SiNx), silicon dioxide (SiO2), magnesium fluoride (MgF2), indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), zinc oxide (ZnO) and their combinations.

[0013] In an embodiment of the light-emitting diode structure of the present invention, the material of the second mirror reflection layer is selected from one of the group consisting of silver (Ag), gold (Au), aluminum (Al), platinum (Pt), titanium (Ti), nickel (Ni) and their combinations.

[0014] To achieve the above object, the present invention further provides a light-emitting diode structure, which includes a permanent substrate, a bonding metal composite layer, a mirror reflection composite layer, and an epitaxial semiconductor composite layer. Among them, the bonding metal composite layer is located on the permanent substrate, the mirror reflection composite layer is located on the bonding metal composite layer, the epitaxial semiconductor composite layer is located on the mirror reflection composite layer, and there is an uneven interface between the mirror reflection composite layer and the epitaxial semiconductor composite layer. Among them, the mirror reflection composite layer includes a first mirror reflection layer and a second mirror reflection layer, and there is a flat interface between the first mirror reflection layer and the second mirror reflection layer.

[0015] After referring to the accompanying drawings and the embodiments described hereinafter, those of ordinary skill in the art can understand the other objects of the present invention, as well as the technical means and implementation schemes of the present invention. Description of the Drawings

[0016] Figure 1 Schematic diagram of the light-emitting diode structure in an embodiment of the present invention;

[0017] Figure 2 Schematic diagram of the light-emitting diode structure in another embodiment of the present invention; and

[0018] Figure 3 Schematic diagram of the light-emitting diode structure in another embodiment of the present invention.

[0019] Description of the Reference Numerals

[0020] 1 Light-emitting diode structure

[0021] 10 Permanent substrate

[0022] 20 Bonding metal composite layer

[0023] 22 First bonding metal layer

[0024] 24 Second bonding metal layer

[0025] 30 Mirror reflection composite layer

[0026] 32 First mirror reflection layer

[0027] 34 Second mirror reflection layer

[0028] 40 Epitaxial semiconductor composite layer

[0029] 42 P-type epitaxial semiconductor layer

[0030] 44 Light-emitting layer

[0031] 46 N-type epitaxial semiconductor layer

[0032] 50 Electrode. Detailed Embodiments

[0033] The following will explain the content of the present invention through embodiments. The embodiments of the present invention are not intended to limit the present invention to be implemented in any specific environment, application, or special manner as described in the embodiments. Therefore, the description of the embodiments is only for the purpose of explaining the present invention, rather than limiting the present invention. It should be noted that in the following embodiments and drawings, elements not directly related to the present invention have been omitted and not shown, and the dimensional relationships between the elements in the drawings are only for easy understanding and are not intended to limit the actual ratio.

[0034] Please refer to Figure 1 , which discloses one of the embodiments of the light-emitting diode structure of 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. Among them, the bonding metal composite layer 20 is located on the permanent substrate 10, the mirror reflection composite layer 30 is located on the bonding metal composite layer 20, the epitaxial semiconductor composite layer 40 is located on the mirror reflection composite layer 30, and the electrode 50 is located on the epitaxial semiconductor composite layer 40. First of all, it should be noted that Figure 1 The light-emitting diode structure of the present invention shown is already the final structure in which the epitaxial composite layer after the epitaxial process is transferred from the temporary epitaxial growth substrate to the permanent substrate by the innovative technology of the present invention. The following will specifically describe the present invention with several embodiments.

[0035] Specifically, the permanent substrate 10 of the light-emitting diode structure 1 of the present invention can be, but is not limited to, a silicon substrate or a sapphire substrate, and an appropriate substrate can be selected according to the actual application requirements and the characteristics of the process. For example, the silicon substrate provides better mechanical structure support strength, which helps to improve the stability during the manufacturing process. In addition, the heat dissipation effect of the silicon substrate is better than that of the sapphire substrate, which helps to control the temperature of the LED chip. Moreover, the silicon substrate is relatively lower in cost than the sapphire substrate, which is an important factor in industrial mass production. In contrast, the sapphire substrate has high transparency to blue light and ultraviolet light, which helps to improve the light output efficiency of the LED chip. In addition, the sapphire substrate has better stability in a high-temperature environment, which is important for the application of high-power LED chips. Moreover, sapphire is a better insulator, which helps to prevent the penetration of current and improve the insulation performance of the component.

[0036] In addition, in one embodiment of the light-emitting diode structure of the present invention, the epitaxial semiconductor composite layer 40 above the permanent substrate 10 can be, but is not limited to, an aluminum gallium indium arsenide (AlGaInAs) double heterostructure. The epitaxial semiconductor composite layer 40 was originally epitaxially stacked on an epitaxial growth substrate (not shown), such as an indium phosphide (InP) substrate. Specifically, in this embodiment, the double heterostructure 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. Among them, the P-type epitaxial semiconductor layer 42 is a carbon (C)-doped aluminum gallium arsenide (AlGaAs) confinement layer. The light-emitting layer 44 is formed by a multiple quantum well (MQW) structure, which includes aluminum gallium arsenide (AlGaAs) as the barrier layer of the multiple quantum well and indium gallium arsenide (InGaAs) as the well layer of the multiple quantum well. In addition, the N-type epitaxial semiconductor layer 46 is a silicon (Si)-doped aluminum gallium arsenide (AlGaAs) confinement layer. It should be noted that the materials described in the above embodiment are only examples, and the present invention is not limited thereto. In practical applications, the materials and their compositions can be adjusted according to the emission wavelength. For example, the epitaxial layer can be aluminum gallium indium phosphide (AlGaInP), indium gallium phosphide (InGaP), aluminum gallium arsenide (AlGaAs), indium gallium arsenide (InGaAs), indium phosphide (InP), etc.

[0037] Secondly, in this embodiment, the mirror reflection composite layer 30 includes a first mirror reflection layer 32 and a second mirror reflection layer 34. Among them, the first mirror reflection layer 32 can be, but is not limited to, composed of a low refractive index dielectric material, which is selected from the group consisting of titanium dioxide (TiO2), silicon nitride (SiNx), silicon dioxide (SiO2), magnesium fluoride (MgF2), indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), zinc oxide (ZnO) and combinations thereof. The second mirror reflection layer 34 can be, but is not limited to, composed of a high reflectivity metal material, which is selected from the group consisting of silver (Ag), gold (Au), aluminum (Al), platinum (Pt), titanium (Ti), nickel (Ni) and combinations thereof.

[0038] In an embodiment of the present invention, considering factors such as the support strength and heat dissipation efficiency of the light-emitting diode structure, the epitaxial semiconductor composite layer 40 in the above light-emitting diode structure must be transferred and bonded to the permanent substrate 10 of the silicon substrate by a metal bonding method from the original epitaxial growth substrate, and then the original epitaxial growth substrate is removed. Therefore, before performing the metal bonding process, first, a first bonding metal layer 22 must be formed on the permanent substrate 10 by metal evaporation. Secondly, a second bonding metal layer 24 is formed by evaporation above the mirror reflection composite layer 30 of the original epitaxial growth substrate. Among them, the materials of the first bonding metal layer 22 and the second bonding metal layer 24 are selected from one of the group consisting of gold (Au), indium (In), and tin (Sn) and their combinations. Moreover, the thicknesses of both the first bonding metal layer 22 and the second bonding metal layer 24 are 1 micrometer (μm) to 2 micrometers (μm).

[0039] As disclosed in the above prior art, when the present invention performs metal bonding on the permanent substrate, similarly, the bonding surfaces between the first bonding metal layer 22 and the second bonding metal layer 24 must be kept flat to ensure the reflection efficiency of the mirror reflection system and avoid reducing the reflection efficiency due to the unevenness of the bonding surfaces of the two. However, on the other hand, in order to increase the bonding strength between the interfaces of the first bonding metal layer 22 and the second bonding metal layer 24 and improve the process yield of metal bonding, the present invention designs the interface between the permanent substrate 10 and the first bonding metal layer 22 as an uneven interface. By increasing the interface area through this uneven interface, the purpose of increasing the bonding strength and improving the process yield of metal bonding can be achieved, so that the epitaxial semiconductor structure can be successfully transferred to the permanent substrate. However, the degree of unevenness between the permanent substrate 10 and the first bonding metal layer 22 must also have an upper limit to avoid the unevenness between the interfaces of the two being too "rough", which indirectly affects the flatness of the mirror reflection composite layer 30 when the first bonding metal layer 22 and the second bonding metal layer 24 are subjected to metal bonding and reduces the reflection efficiency of its light. Specifically, according to the research of the present invention, the roughness Ra value of the uneven interface between the permanent substrate 10 and the first bonding metal layer 22 must be less than 0.5 micrometer (μm) to improve the bonding strength between the two bonding metal layers on the premise of ensuring the flatness of the mirror reflection composite layer 30.

[0040] In another embodiment of the present invention, a patterned process needle can be used to achieve the purpose of having an uneven interface between the bonding metal composite layer and the permanent substrate. Please refer to Figure 2, specifically, after the patterning process is completed, a patterned interface is formed between the first bonding metal layer 22 and the permanent substrate 10, and the pattern depth value of this patterned interface must also be less than 0.5 micrometers (μm) to ensure the flatness of the mirror reflection composite layer 30 while improving the bonding strength between the two bonding metal layers and avoiding reducing the reflection efficiency of the mirror layer.

[0041] It should be noted that after the epitaxial process is completed on the epitaxial growth substrate, the surface of the epitaxial semiconductor composite layer 40 is usually an uneven non-planar surface. Therefore, when the coating process of the mirror system is subsequently performed on the epitaxial semiconductor composite layer 40, the first mirror reflection layer 32 in the mirror reflection composite layer 30 usually also remains formed on the epitaxial semiconductor composite layer 40 in this uneven manner, so that the interface between the first mirror reflection layer 32 and the epitaxial semiconductor composite layer 40 in the mirror reflection composite layer 30 is also an uneven interface. At this time, if the metal coating process of the second mirror reflection layer 34 in the mirror reflection composite layer 30 is continued without any treatment, the interface between the first mirror reflection layer 32 and the second mirror reflection layer 34 is also an uneven interface. This uneven interface will reduce the reflection efficiency of the subsequent light-emitting diode light and reduce the light extraction rate of the light-emitting diode. In view of this, to avoid the above problems, please refer to Figure 3 , the present invention particularly performs a polishing process after the coating process of the first mirror reflection layer 32 is completed and before the coating process of the second mirror reflection layer 34 is performed. After improving the uneven state of the surface of the first mirror reflection layer 32 with high and low undulations, the coating process of the second mirror reflection layer 34 is then performed. Therefore, after the mirror coating process is completed, the 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 is a flat interface, so as to improve the reflection efficiency of the mirror system and thus increase the light extraction rate of the light-emitting diode.

[0042] The above embodiments are only used to illustrate the implementation schemes of the present invention and explain the technical features of the present invention, and are not used to limit the protection scope of the present invention. Any easily completed changes or equivalent arrangements by those skilled in the art belong to the scope claimed by the present invention, and the scope of the right protection of the present invention shall be subject to the claims.

Claims

1. A light-emitting diode structure, comprising: A permanent substrate; A bonding metal composite layer located on the permanent substrate; A mirror reflection composite layer located on the bonding metal composite layer; and An epitaxial semiconductor composite layer located on the mirror reflection composite layer, Among them, There is an uneven interface between the bonding metal composite layer and the permanent substrate, and the surface roughness of the uneven interface is less than 0.5 microns.

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

3. The light-emitting diode structure according to claim 2, wherein the materials of the first bonding metal layer and the second bonding metal layer are selected from one of the groups consisting of gold, indium, tin and combinations thereof.

4. The light-emitting diode structure according to claim 2, wherein the thicknesses of the first bonding metal layer and the second bonding metal layer are from 1 micron to 2 microns.

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

6. The light-emitting diode structure according to claim 1, wherein the mirror reflection composite layer comprises a first mirror reflection layer and a second mirror reflection layer, and there is a flat interface between the first mirror reflection layer and the second mirror reflection layer.

7. The light-emitting diode structure according to claim 6, wherein the material of the first mirror reflection layer is selected from one of the groups consisting of titanium dioxide, silicon nitride, silicon dioxide, magnesium fluoride, indium tin oxide, indium zinc oxide, indium gallium zinc oxide, zinc oxide and combinations thereof.

8. The light-emitting diode structure according to claim 6, wherein the material of the second mirror reflection layer is selected from one of the groups consisting of silver, gold, aluminum, platinum, titanium, nickel and combinations thereof.

9. A light-emitting diode structure, comprising: A permanent substrate; A bonding metal composite layer located on the permanent substrate; A mirror reflection composite layer located on the bonding metal composite layer; and An epitaxial semiconductor composite layer located on the mirror reflection composite layer, and there is an uneven interface between the mirror reflection composite layer and the epitaxial semiconductor composite layer, Among them, The mirror reflection composite layer comprises a first mirror reflection layer and a second mirror reflection layer, and there is a flat interface between the first mirror reflection layer and the second mirror reflection layer.

10. The light-emitting diode structure according to claim 9, wherein the material of the first mirror reflection layer is selected from one of the groups consisting of titanium dioxide, silicon nitride, silicon dioxide, magnesium fluoride, indium tin oxide, indium zinc oxide, indium gallium zinc oxide, zinc oxide and combinations thereof.

11. The light-emitting diode structure according to claim 9, wherein the material of the second mirror reflection layer is selected from one of the groups consisting of silver, gold, aluminum, platinum, titanium, nickel and combinations thereof.

12. The light-emitting diode structure according to claim 9, wherein there is an uneven interface between the bonding metal composite layer and the permanent substrate, and the surface roughness of the uneven interface is less than 0.5 microns.

13. The light-emitting diode structure according to claim 12, wherein the bonding metal composite layer comprises a first bonding metal layer and a second bonding metal layer, and a flat interface is between the first bonding metal layer and the second bonding metal layer.

14. The light-emitting diode structure according to claim 13, wherein the materials of the first bonding metal layer and the second bonding metal layer are selected from one of the group consisting of gold, indium, and tin and combinations thereof.

15. The light-emitting diode structure according to claim 13, wherein the thicknesses of the first bonding metal layer and the second bonding metal layer are from 1 micrometer to 2 micrometers.

16. The light-emitting diode structure according to claim 9, wherein a patterned interface is between the bonding metal composite layer and the permanent substrate, and the pattern depth value of the patterned interface is less than 0.5 micrometer.

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