Light emitting diode and light emitting device

Abstract

The utility model relates to the technical field of semiconductor electronic device provides a kind of light emitting diode and light emitting device.Light emitting diode at least includes: substrate, with oppositely arranged first surface and second surface;Several convex pattern structures, interval setting in the above of the first surface of substrate;Protective layer, setting in the above of the first surface, and covering convex pattern structure and first surface;Epitaxial structure, setting in the above of protective layer, from bottom to top including first semiconductor layer, active layer and second semiconductor layer sequentially laminated;Wherein, the refractive index of protective layer is less than the refractive index of substrate.Light emitting diode made of this kind of structure can prevent pattern structure on substrate from being damaged during chip processing, maintain the integrity of pattern structure, increase the amount of light reflection when light passes through pattern structure, enhance the reflection effect, and thus improve the front light efficiency of light emitting diode and the brightness of device.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of semiconductor electronic device, especially relates to a light emitting diode and light emitting device. BACKGROUND

[0002] In the light emitting diode (LED) industry, in order to obtain higher quality, less dislocation density epitaxial layer, usually adopt heteroepitaxial growth technology, for example, on SiC substrate, sapphire substrate, Si substrate carries out GaN, GaAs etc. The growth of epitaxial growth. At present, GaN epitaxial and sapphire substrate heteroepitaxial growth technology is more mature. Patterned sapphire substrate (PSS) technology is used for heteroepitaxial growth, which can effectively reduce the dislocation density of GaN epitaxial material, thereby reducing the non-radiative recombination of active layer, reducing the reverse leakage current, improving the life of LED;The light emitted by the active layer changes the exit angle of the total reflection light after multiple scattering through the GaN and sapphire substrate interface, increases the probability of LED light from the sapphire substrate, thereby improving the light extraction efficiency.

[0003] In the current existing light emitting diode, when the light enters the patterned sapphire substrate from the active layer, since the refractive index (1.7~1.8) of sapphire substrate and the refractive index (about 2.5) of GaN are relatively small, the light is easy to be transmitted at the interface of patterned sapphire substrate, and the patterned sapphire substrate is damaged in the process of epitaxial growth, which reduces the reflectivity of light towards the epitaxial light emitting surface, and reduces the light emitting efficiency of the light emitting diode.

[0004] Therefore, when manufacturing the light emitting diode, how to protect the pattern structure on the substrate from being damaged, improve the epitaxial growth quality, and further improve the light emitting efficiency of the light emitting diode has become one of the technical problems to be solved by the technical personnel in the field. Utility model content

[0005] In order to solve the deficiency of the patterned substrate in the chip manufacturing process in the prior art, the utility model provides a light emitting diode and light emitting device, which can protect the pattern structure on the substrate from being damaged in the chip manufacturing process, increase the (total) reflection of light in the pattern structure area of the substrate, and further improve the light emitting efficiency of the light emitting diode.

[0006] To achieve at least one of the above objects or other objectives, the utility model provides a light emitting diode, at least includes: substrate, has opposite first surface and second surface, a plurality of convex pattern structure is arranged in the first surface of substrate above, the protective layer is arranged in the first surface above, and the first surface and a plurality of convex pattern structure are covered, epitaxial structure is arranged in the protective layer above, from bottom to top includes first semiconductor layer, active layer and second semiconductor layer which are stacked in turn, wherein, the refractive index of protective layer is less than the refractive index of substrate.

[0007] In some embodiments, the thickness of the protective layer is no more than 2.5 microns. In some embodiments, the thickness of the protective layer is greater than or equal to 3 microns.

[0008] In some embodiments, on the first surface of the substrate, the protective layer is divided into a first region and a second region. From the top of the first surface of the substrate, the second region is located at the periphery of the first region; the epitaxial structure is located in the first region, the thickness of the protective layer in the first region is H1, the thickness of the protective layer in the second region is H2, and H1>H2.

[0009] In some embodiments, the thickness difference between H1 and H2 is no more than 0.5 microns.

[0010] In some embodiments, in the second region, the thickness of the protective layer is unevenly distributed.

[0011] In some embodiments, the protective layer is a first DBR structure, and the first DBR structure is a stacked structure composed of first sub-layers and second sub-layers alternately, wherein the refractive index of the first sub-layer is less than the refractive index of the second sub-layer.

[0012] In some embodiments, when the protective layer is a first DBR structure, in the first DBR structure, the sub-layer closest to and farthest from the first surface of the substrate is a first sub-layer, and the thickness of the first sub-layer farthest from the first surface of the substrate is greater than or equal to 200 angstroms.

[0013] In some embodiments, a second DBR structure is provided below the second surface of the substrate, and the second DBR structure is a stacked structure composed of third sub-layers and fourth sub-layers alternately, wherein the stacked structure of the third sub-layers and the fourth sub-layers is at least one group, and the third sub-layers and the fourth sub-layers have different refractive indexes.

[0014] In some embodiments, a buffer layer is provided between the protective layer and the epitaxial structure.

[0015] In some embodiments, the refractive index of the epitaxial structure is greater than the refractive index of the substrate, and the refractive index of the substrate is greater than the refractive index of the protective layer.

[0016] In some embodiments, the sidewall of the epitaxial structure has an inclined angle with the substrate, and the inclined angle is an acute angle.

[0017] To achieve at least one of the above advantages or other advantages, the utility model also provides a light emitting device, it can include the light emitting diode of any one of preceding.

[0018] The utility model provides a light emitting diode and light emitting device, compared with prior art light emitting diode, at least has following advantage:

[0019] 1, in the patterned substrate, by setting the protective layer between the protruding pattern structure and epitaxial structure, the protruding pattern structure is formed complete covering protection by the protective layer, prevent the protruding pattern structure is destroyed in subsequent process, increase the reflection of light in the protruding pattern structure area to the light emitting surface, reduce the transmission of light in the back of patterned substrate (non the side of setting epitaxial structure), and then improve the light emitting efficiency of light emitting diode.

[0020] 2, in the patterned substrate, the refractive index of protective layer is less than the refractive index of substrate, when light is incident to the patterned substrate, the total reflection of light to the light emitting surface can be increased through the protective layer, and then the light emitting efficiency of light emitting diode is improved, and the brightness of device is improved.

[0021] 3, in the patterned substrate, by setting the DBR structure of different sublayer interlaced layering with different refractive index on the back of substrate (non the side of setting epitaxial structure), the reflection of light after the transmission of patterned substrate can be increased, and then the light emitting amount of light emitting surface of light emitting diode is increased, the light emitting efficiency is improved, and the brightness of device is improved. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical scheme in the embodiments of the utility model or prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description, and obviously, the drawings in the following description are some embodiments of the utility model, and for those skilled in the art, other drawings can also be obtained without creative labor according to these drawings.

[0023] Figure 1 It is a structure schematic view of an embodiment of prior art light emitting diode with patterned substrate;

[0024] Figure 2 It is a sectional structure schematic view of the first embodiment of patterned substrate in the utility model;

[0025] Figure 3 It is Figure 2 It is a sectional structure schematic view of the first embodiment of patterned substrate in the utility model;

[0026] Figure 4This is a cross-sectional view of the second embodiment of the patterned substrate in this utility model;

[0027] Figure 5 This is a cross-sectional view of the third embodiment of the patterned substrate in this utility model;

[0028] Figure 6 for Figure 5 A schematic cross-sectional view of an embodiment of the back-side DBR structure in the patterned substrate shown.

[0029] Figure 7 This is a cross-sectional view of the first embodiment of the light-emitting diode in this utility model;

[0030] Figure 8 for Figure 7 A schematic diagram of the optical path of the light-emitting diode in the patterned substrate region (indicated by the arrow);

[0031] Figure 9 This is a cross-sectional view of the second embodiment of the light-emitting diode in this utility model;

[0032] Figure 10 This is a schematic diagram of the structure of a patterned substrate after the epitaxial structure fabrication process is completed in this utility model.

[0033] Reference numerals: 100-patterned substrate, 200-light-emitting diode, 10-substrate, 10a-first surface, 10b-second surface, 12-patterned structure, 14-protective layer, 15-first DBR structure, 151-bottom layer, 152-intermediate layer, 153-top layer, S1-first region, S2-second region, 16-second DBR structure, 161-top layer, 162-intermediate layer, 163-bottom layer, 18-buffer layer, 20-epitaxy structure, 21-first semiconductor layer, 22-active layer, 23-second semiconductor layer, 30-transparent conductive layer, 40-current blocking layer, 50-first electrode, 60-second electrode, H / H1 / H2-thickness, α-tilt angle. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0035] In the description of the utility model, it needs to be understood that, the orientation or position relation indicated by the terms "center", "transverse", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is the orientation or position relation based on the drawings shown, and is only for the convenience of describing the utility model and simplifying the description, and therefore cannot be understood as indicating or implying that the device or component indicated must have a specific orientation, or be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the utility model. In addition, the terms "first" and "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features limited by "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the utility model, unless otherwise specified, the meaning of "a plurality of" is two or more. In addition, the term "includes" and any variation thereof means "at least includes".

[0036] In the description of the utility model, it needs to be understood that, the orientation or position relation indicated by the terms "center", "transverse", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is the orientation or position relation based on the drawings shown, and is only for the convenience of describing the utility model and simplifying the description, and therefore cannot be understood as indicating or implying that the device or component indicated must have a specific orientation, or be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the utility model. In addition, the terms "first" and "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features limited by "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the utility model, unless otherwise specified, the meaning of "a plurality of" is two or more. In addition, the term "includes" and any variation thereof means "at least includes".

[0037] The terms used herein are merely used to describe specific embodiments and are not intended to limit exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms "a," "an," and "the" used herein are also intended to include the plural forms. It should also be understood that the terms "including" and / or "comprising" as used herein specify the presence of stated features, integers, steps, operations, units and / or components, and do not preclude the presence or addition of one or more other features, integers, steps, operations, units, components and / or combinations thereof.

[0038] The structural dimensions of the patterned substrate and the light-emitting diode in the specific embodiments shown in the drawings are not drawn in accordance with the actual size. The thickness of the pattern structure and each layer in the actual object is relatively thin. In order to facilitate understanding and description of the structural characteristics, the thickness and other characteristics of the levels in the schematic diagram of the drawings are enlarged accordingly, and do not correspond to the actual object.

[0039] Please refer to Figure 1 , Figure 1A schematic diagram of a structure of an embodiment of a light emitting diode with a patterned substrate. At present, for example in the process of a flip chip light emitting diode, a patterned substrate with a convex pattern structure is used to improve the growth quality of epitaxy, thereby improving the light extraction efficiency. The light extraction efficiency of a light emitting diode is one of the important performance indicators of the device, and in subsequent process technology, high-temperature acid and the like are used to etch the epitaxial structure (such as a GaN epitaxial layer) laterally to form a reverse triangular slope on the side of the light emitting diode (LED chip), thereby improving the light extraction efficiency of the light emitting diode. At the same time, the corrosive nature of high-temperature acid and the like will also corrode the pattern structure on the patterned substrate. As shown in Figure 1 the SEM image obtained by electron beam scanning of the existing flip chip light emitting diode made of a patterned substrate, after epitaxial growth, the convex pattern structure on the patterned substrate facing the epitaxial structure is damaged due to the influence of etching raw materials on the patterned substrate during the process. Specifically, as shown in the left view, the heights (thicknesses) of the plurality of convex pattern structures on the patterned substrate are different and the difference is large, the scattering loss of light in the pattern structure region increases, the internal total reflection decreases, the light extraction efficiency of the light emitting diode is reduced, and the device stability and reliability of the light emitting diode are also reduced. Figure 1

[0040] Embodiment 1

[0041] Please compare Figure 1 Please refer to Figure 2 , Figure 2 A schematic diagram of a side cross-sectional structure of a first embodiment of a patterned substrate in the utility model. In order to achieve at least one of the advantages or other advantages, an embodiment of the utility model provides a patterned substrate 100, at least comprising: a substrate 10, a plurality of convex pattern structures 12 and a protective layer 14. The substrate 10 has a first surface 10a and a second surface 10b arranged oppositely. The plurality of convex pattern structures 12 are arranged above the first surface 10a of the substrate 10. The spacing between the plurality of convex pattern structures 12 exposes the first surface 10a of the substrate 10. The protective layer 14 is arranged above the first surface 10a and completely covers the plurality of convex pattern structures 12 and the exposed first surface 10a between the convex pattern structures 12.

[0042] Please refer to Figure 2 ​In the illustrated example, the first surface 10a of the substrate 10 is defined as the upper surface / above and the second surface 10b of the substrate 10 is defined as the lower surface / below in the vertical direction with reference to the substrate 10. Optionally, the material of the substrate 10 can be one or more of Al2O3 (main component of sapphire), ZnO, Si, SiC, SiO2, SiN. In the present embodiment, the sapphire substrate 10 is taken as an example for illustration. The refractive index of the sapphire substrate 10 is 1.7-1.8.

[0043] The plurality of protruding pattern structures 12 are arranged at intervals on the first surface 10a of the substrate 10 and are located above the first surface 10a. The end of the protruding pattern structure 12 that is attached to the first surface 10a of the substrate 10 is the bottom end, and the end of the protruding pattern structure 12 that is away from the first surface 10a of the substrate 10 is the top end. The cross-sectional width of the top end of the protruding pattern structure 12 is smaller than the cross-sectional width of the bottom end of the protruding pattern structure 12. For example, the shape of the protruding pattern structure 12 can be one or more of a conical shape, a cannonball shape, a conical body, a regular polygonal pyramid, a hemispherical body, a circular truncated cone body, a spherical segment body, a circular cylinder, a regular polyhedron, a square column, a Mongolian yurt, and any irregular geometric body. Optionally, the height (thickness) of each protruding pattern structure 12 is between 1 μm and 2.5 μm. The material of the protruding pattern structure 12 is an optical thin film material, and the refractive index of the material is smaller than the refractive index of the substrate 10. Optionally, the material of the protruding pattern structure 12 can be one or more of Al2O3, SiO2, Si3N4, ZnO2, Si, SiC, GaAs, Ti3O5, or TiO2. In the present embodiment, the material of the protruding pattern structure 12 is Al2O3, which has the same refractive index as the substrate 10.

[0044] In some embodiments, the protective layer 14 is arranged above the first surface 10a and completely covers the plurality of protruding pattern structures 12 and the exposed first surface 10a between the protruding pattern structures 12. As shown in FIG. 1, the protective layer 14 is arranged on the first surface 10a of the substrate 10 and covers the plurality of protruding pattern structures 12 and the exposed first surface 10a between the protruding pattern structures 12. Figure 2As shown, the protective layer 14 is formed above the first surface 10a of the substrate 10. The protective layer 14 has a certain thickness at the top end of the protruding pattern structure 12, and completely covers the gap between the protruding pattern structures 12 and the exposed first surface 10a of the substrate 10, thereby completely covering the bottom end to the top end of the protruding pattern structure 12 to protect the protruding pattern structure 12 from being damaged before the epitaxial structure growth. Furthermore, the protective layer 14 will not be removed during the growth of the epitaxial structure, and is even retained between the substrate 10 and the epitaxial structure after the device is formed. The complete covering of the protruding pattern structure 12 by the protective layer 14 can prevent the top end of the protruding pattern structure 12 from being damaged during the growth process of the epitaxial structure, reduce the total reflection and scattering loss of light at the first surface 10a of the substrate 10, and improve the growth quality of the epitaxial structure, thereby improving the light extraction efficiency of the light emitting diode and enhancing the brightness and performance of the device.

[0045] In some embodiments, as shown in FIG. 1, the protective layer 14 is formed above the first surface 10a of the substrate 10. The protective layer 14 has a certain thickness at the top end of the protruding pattern structure 12, and completely covers the gap between the protruding pattern structures 12 and the exposed first surface 10a of the substrate 10, thereby completely covering the bottom end to the top end of the protruding pattern structure 12 to protect the protruding pattern structure 12 from being damaged before the epitaxial structure growth. Furthermore, the protective layer 14 will not be removed during the growth of the epitaxial structure, and is even retained between the substrate 10 and the epitaxial structure after the device is formed. The complete covering of the protruding pattern structure 12 by the protective layer 14 can prevent the top end of the protruding pattern structure 12 from being damaged during the growth process of the epitaxial structure, reduce the total reflection and scattering loss of light at the first surface 10a of the substrate 10, and improve the growth quality of the epitaxial structure, thereby improving the light extraction efficiency of the light emitting diode and enhancing the brightness and performance of the device. Figure 2 As shown, the protective layer 14 fills the first surface 10a of the substrate 10 between the adjacent protruding pattern structures 12, and the protective layer 14 has a certain thickness at the top end of the protruding pattern structure 12, thereby forming a flat surface above the top end of the protruding pattern structure 12 (before the epitaxial structure process). Optionally, the height (thickness) of each protruding pattern structure 12 is between 1 μm and 2.5 μm, and at this time, the thickness H of the protective layer 14 is greater than the height of the protruding pattern structure 12, and the thickness H of the protective layer 14 is greater than or equal to 3 microns. The thickness H of the protective layer 14 is of a filling type, and after the chip process is completed, the transparent conductive layer remaining between the adjacent protruding pattern structures 12 during the process can be more effectively removed, thereby preventing the light emitting diode from leaking and other phenomena. Further, considering that the overall thickness of the subsequent light emitting diode cannot be too thick, the thickness H of the protective layer 14 ranges from 3 microns to 6 microns.

[0046] Optionally, the material of the protective layer 14 is a light-transmitting material. Optionally, the material of the protective layer 14 can be a non-conductive light-transmitting insulating material. The material of the protective layer 14 can be a light-transmitting material that is conductive or non-conductive. The refractive index of the protective layer 14 is less than the refractive index of the substrate 10. Optionally, the thickness of the protective layer 14 ranges from 1 to 3 microns. For example, the material of the protective layer 14 can be methyl low-refractive silica gel (refractive index less than 1.43), SiO2 (refractive index about 1.5), DBR (SiO2+TiO2), etc. When light passes through the substrate 10, the refractive index of the protective layer 14 is less than the refractive index of the substrate 10, so that the light will not be absorbed by the substrate 10 and can be reflected in time through the protruding pattern structure 12 and the protective layer 14 to the light emitting surface of the light emitting diode, thereby improving the front light extraction efficiency of the light emitting diode.

[0047] For example, in some embodiments, the material of the protective layer 14 is methyl low-refractive silica gel, which has a refractive index less than 1.43 and less than the refractive index of the sapphire substrate 10. A layer of methyl low-refractive silica gel is coated on the first surface 10a of the substrate 10 by spin coating during the formation of the substrate 10, and is baked at 150°C for 30 minutes. The thickness of the methyl low-refractive silica gel can be controlled by the rotation speed of the spin coating. The methyl low-refractive silica gel is not removed in subsequent epitaxial structure growth and chip processing procedures. In the epitaxial structure growth and chip processing procedures, the protective layer 14 formed by the methyl low-refractive silica gel can resist high-temperature acid etching, so that the raised pattern structure 12 on the first surface 10a of the substrate 10 is not damaged by the high-temperature acid etching. The light reflection amount of the area of the first surface 10a of the substrate 10 is increased, which is beneficial to improving the light extraction efficiency and the brightness of the light-emitting diode.

[0048] In another embodiment, the protective layer 14 is a single layer of SiO2. In this case, the material of the protective layer 14 is a light-transmitting insulating material.

[0049] In some other embodiments, the material of the protective layer 14 can be a light-reflecting material (or a retroreflective material, a back reflector), so as to increase the reflection amount of the light emitted by the active layer in the epitaxial structure on the light-emitting surface of the protective layer 14, thereby improving the light extraction efficiency and the brightness of the light-emitting diode.

[0050] Embodiment 2

[0051] In combination with Figure 2 Referring to Figure 3 , Figure 3 is Figure 2 FIG. 2 shows a cross-sectional structure of an embodiment of the protective layer in the patterned substrate. The same parts of Embodiment 2 as those of Embodiment 1 are not described again.

[0052] Optionally, the protective layer 14 can be a DBR structure. The DBR structure, also known as a distributed Bragg reflector, is a periodic structure composed of two materials with different refractive indexes arranged in an ABAB or ABA manner. The DBR structure can reduce the loss of light in the light-emitting diode and improve the light reflection rate in the light-emitting diode, thereby improving the light extraction efficiency. In some embodiments, the protective layer 14 is a first DBR structure 15, and the first DBR structure 15 is a stacked structure composed of first sub-layers and second sub-layers arranged alternately. The refractive index of the first sub-layer is less than the refractive index of the second sub-layer. In the first DBR structure 15, the sub-layers closest to and farthest from the first surface 10a of the substrate 10 are the first sub-layers, and the thickness of the first sub-layer farthest from the first surface 10a of the substrate 10 is greater than or equal to 200 angstroms. Optionally, the stacked structure of the first sub-layers and the second sub-layers is at least two groups.

[0053] Referring toFigure 3 The material of the first sub-layer and the second sub-layer has corrosion resistance and strong stability. Optionally, the material of the first sub-layer is SiO2, and the material of the second sub-layer is TiO2. For example, the first DBR structure 15 is a stacked structure of SiO2 and TiO2 alternately arranged; further, the stacked structure of SiO2 and TiO2 is at least two groups. The refractive index of SiO2 is about 1.5, and the refractive index of TiO2 is 2.2-2.8. The first DBR structure 15 includes a bottom layer 151, an intermediate layer 152, and a top layer 153. In the vertical direction, the bottom layer 151 of the first DBR structure 15 is in contact / adhesion with the first surface 10a of the substrate 10 above the first surface 10a of the substrate 10. The bottom layer 151 is defined as the innermost layer close to the first surface 10a, that is, the bottom layer 151 is the first sub-layer closest to the first surface 10a of the substrate 10, and the material of the bottom layer 151 is SiO2 at this time. The intermediate layer 152 can be TiO2+SiO2+TiO2. The intermediate layer 152 can also be a stacked structure (multi-layer structure) of multiple groups of TiO2 and SiO2 alternately arranged, so that the combination of the bottom layer 151 and the last group of the intermediate layer 152 is a stacked structure of two or more groups of SiO2+TiO2. The top layer 153 of the first DBR structure 15 is arranged farthest away from the first surface 10a. The top layer 153 is defined as the outermost layer farthest away from the first surface 10a, that is, the top layer 153 is the first sub-layer farthest away from the first surface 10a of the substrate 10, and the material of the top layer 153 is SiO2 at this time, and the thickness of SiO2 is greater than or equal to 200 angstroms. The arrangement of SiO2 in the bottom layer 151 and the top layer 153 of the first DBR structure 15 can ensure that the refractive index of the protective layer 14 on the side of the substrate 10 (the bottom layer 151) is less than the refractive index of the substrate 10, and the refractive index of the protective layer 14 on the side of the epitaxial structure (the top layer 153) is less than the refractive index of the epitaxial structure (for example, the refractive index of GaN material is about 2.5), so that the light emitted by the epitaxial structure of the light-emitting diode to the patterned substrate 100 can be more reflected to the light-emitting surface, thereby improving the light extraction efficiency of the light-emitting diode.

[0054] When the protective layer 14 is the first DBR structure 15, the patterned structure 12 protruding on the substrate 10 can be coated and protected, and the first DBR structure 15 can increase the reflection of light on the first surface 10a of the substrate 10, reduce the shielding or absorption of light by the substrate 10, and improve the light extraction efficiency of the light-emitting diode and the brightness of the device.

[0055] When the protective layer 14 is the first DBR structure 15, no additional DBR structure needs to be arranged below the second surface 10b of the substrate 10 to increase the reflection of light on the back surface of the substrate 10, thereby improving the light extraction efficiency of the light-emitting diode.

[0056] Embodiment 3

[0057] In combinationFigure 2 Referring to Figure 4 , Figure 4 is a cross-sectional structure schematic view of a second embodiment of the patterned substrate in the present application. The same parts in Embodiment 3 and Embodiment 1 are not repeated here.

[0058] Referring to Figure 4 , unlike the filling type setting of the protective layer 14 in Embodiment 1, in some embodiments, the protective layer 14 is attached along the surface of the protruding pattern structure 12 to prevent the top end of the pattern structure 12 from being damaged in subsequent processes. As shown in Figure 4 , the shape of the protective layer 14 is basically consistent with the shape of the pattern structure 12. The thickness H of the protective layer 14 between adjacent pattern structures 12 is less than the height (thickness) of the pattern structure 12 and covers the first surface 10a of the substrate 10 exposed between adjacent pattern structures 12. Optionally, the height (thickness) of each protruding pattern structure 12 is between 1 μm and 2.5 μm, and at this time, the thickness H of the protective layer 14 is not more than 2.5 microns (i.e. H≦2.5 microns). The protective layer 14 is attached and set, and in subsequent processes, complete protection is formed on the top end of the protruding pattern structure 12 while the transparent conductive layer and the current blocking layer are left between adjacent protruding pattern structures 12. When the protective layer 14 is attached and set, the transparent conductive layer and the current blocking layer left between the protruding pattern structures 12 can be more, and it is relatively more complex to remove, and a small part may be inevitably left after removal.

[0059] Embodiment 4

[0060] In combination with Figure 2 Referring to Figure 5 , Figure 5 is a cross-sectional structure schematic view of a third embodiment of the patterned substrate in the present application. The same parts in Embodiment 4 and Embodiment 1 are not repeated here.

[0061] Referring to Figure 5In some embodiments, the light emitting diode made of the patterned substrate 100 is a vertical type light emitting diode, and the light emitting surface is located above the first surface 10a of the substrate 10. In order to reduce the obstruction or absorption of the light emitted by the epitaxial structure by the second surface 10b of the substrate 10, an additional second DBR structure 16 can also be provided below the second surface 10b (back surface) of the substrate 10. The second DBR structure 16 is a stacked structure of third sub-layers and fourth sub-layers, and the stacked structure of the third sub-layers and the fourth sub-layers is at least one group, and the third sub-layers and the fourth sub-layers have different refractive indexes. The second DBR structure 16 can be an ABA stacked structure. The light emitted by the epitaxial structure can be reflected to the light emitting surface by the second DBR structure 16 after being transmitted to the second surface 10b through the substrate 10, thereby increasing the reflectivity of the patterned substrate 100 to the light emitted by the epitaxial structure and improving the light emitting efficiency and brightness of the light emitting diode.

[0062] In combination Figure 5 Referring to Figure 6 , Figure 6 For Figure 5 FIG. 7 shows a cross-sectional structure schematic diagram of an embodiment of the back surface DBR structure in the patterned substrate. The materials of the third sub-layers and the fourth sub-layers have corrosion resistance and strong stability. Optionally, in the second DBR structure 16, the material of the third sub-layers is SiO2, and the material of the fourth sub-layers is TiO2; or the material of the third sub-layers is TiO2, and the material of the fourth sub-layers is SiO2. Optionally, in an embodiment, the stacked structure of the third sub-layers and the fourth sub-layers is at least 10 groups. For example, the second DBR structure 16 is a stacked structure of SiO2 and TiO2 alternately arranged. Further, the stacked structure of SiO2 and TiO2 is at least one group. The refractive index of SiO2 is about 1.5, and the refractive index of TiO2 is 2.2-2.8. Optionally, the thickness of the second DBR structure 16 is 3-5 microns, so as to have a good reflection effect on the light transmitted through the patterned substrate 100.

[0063] In an embodiment, the second DBR structure 16 comprises a top layer 161, an intermediate layer 162 and a bottom layer 163. In the vertical direction, the top layer 161 of the second DBR structure 16 is in contact / adhesion with the second surface 10b of the substrate 10 below the second surface 10b of the substrate 10. The top layer 161 is defined as the innermost layer close to the second surface 10b, and the material of the top layer 161 is SiO2. The intermediate layer 162 can be a single layer of TiO2, or a stacked structure (multi-layer structure) of TiO2 and SiO2 arranged alternately. The bottom layer 163 of the second DBR structure 16 is arranged farthest from the second surface 10b. The arrangement of the top layer 161 and the bottom layer 163 of the second DBR structure 16 with SiO2 can ensure that the refractive index of the side of the second DBR structure 16 facing the substrate 10 (the top layer 161) is less than the refractive index of the substrate 10, and the refractive index of the bottom layer 163 of the second DBR structure 16 is less than the refractive index of the intermediate layer 162 (the material of the intermediate layer 163 in adhesion with the bottom layer 163 is TiO2, and the refractive index of TiO2 is greater than the refractive index of SiO2), so that the emitted light of the epitaxial structure can be more reflected to the light emitting surface after being transmitted through the patterned substrate 100, thereby improving the light extraction efficiency of the light emitting diode.

[0064] Optionally, in some embodiments, the second DBR structure 16 is arranged in the patterned substrate 100 in combination with the first DBR structure 15. Figure 3 Referring to Figure 5 , the second DBR structure 16 is arranged in the patterned substrate 100 below the second surface 10b of the substrate 10, and the protection layer 14 is arranged for the first DBR structure 15, so that the emitted light of the epitaxial structure can be more reflected to the light emitting surface after being transmitted through the patterned substrate 100, thereby improving the light extraction efficiency of the light emitting diode and improving the brightness of the light emitting diode.

[0065] Embodiment 5

[0066] Please refer to Figure 2 , Figure 3 , Figure 5 and Figure 6 Referring to Figure 7 and Figure 8 , Figure 7 is a sectional structure schematic view of the first embodiment of the light emitting diode in the utility model, Figure 8 is Figure 7The light path (indicated by arrows) of the illustrated light-emitting diode in the patterned substrate region is schematically shown. To achieve at least one of the advantages or other advantages, an embodiment of the present application provides a light-emitting diode 200, at least comprising: a substrate, which is the patterned substrate 100 as defined in any one of the preceding embodiments; a buffer layer 18 arranged above the protection layer 14 in the patterned substrate 100; an epitaxial structure 20 arranged above the buffer layer 18, comprising from bottom to top a first semiconductor layer 21, an active layer 22 and a second semiconductor layer 23 which are sequentially stacked; a transparent conductive layer 30 arranged above the second semiconductor layer 23, exposing a part of the surface of the second semiconductor layer 23 away from the active layer 22; a first electrode 50 and a second electrode 60 arranged above the first semiconductor layer 21 and the second semiconductor layer 23 respectively, and electrically connected to the first semiconductor layer 21 and the second semiconductor layer 23 respectively; a current blocking layer 40 between the first semiconductor layer 21 and the first electrode 50 and between the second semiconductor layer 23 and the second electrode 60. The light-emitting diode 200 can further comprise an insulating layer (not shown in the figure) arranged above the transparent conductive layer 30, covering at least a part of the upper surface of the buffer layer 18, the first semiconductor layer 21 and the second semiconductor layer 23 away from the substrate, a part of the upper surface of the transparent conductive layer 30, a part of the upper surface of the protection layer 14, and a part of the upper surface of the first electrode 50 and the second electrode 60.

[0067] As Figure 7 shown, the protection layer 14 can be divided into a first region S1 and a second region S2 on the first surface 10a of the substrate 10. As viewed from above the first surface 10a of the substrate 10, the second region S2 is located at the periphery of the first region S1. Further, the area of the second region S2 is smaller than the area of the first region S1. In subsequent processes, the epitaxial structure 20 is located in the first region S1. The thickness of the protection layer 14 in the first region S1 is defined as H1, and the thickness of the protection layer 14 in the second region S2 is defined as H2, H1>H2. Among different regions, the difference in thickness of the protection layer 14 does not exceed 0.5 microns, i.e. |H1-H2|≦0.5 microns. In this way, the thickness of the top region of the protection layer of the pattern structure 12 can be ensured to be sufficient, avoiding the protection layer 14 being etched too much in subsequent processes and damaging the integrity of the top of the pattern structure 12, thereby affecting the protection effect of the protection layer 14 on the pattern structure 12, to increase the reflection of light on the side of the protection layer 14 away from the substrate 10, and to improve the light extraction efficiency. Optionally, compared with the first region S1, the number of the raised pattern structures 12 corresponding to the protection layer 14 in the second region S2 is smaller.

[0068] In the epitaxial structure growth and chip processing procedures, the surface of the protective layer 14 away from the substrate 10 in the second region S2 is etched, so that the thickness of the protective layer 14 in the second region S2 is unevenly distributed. It can be understood that, after the epitaxial structure growth and chip processing procedures are completed, the surface of the protective layer 14 away from the substrate 10 in the second region S2 is a non-smooth flat surface, which is a rough surface with concave-convex structure. In this way, the light reflection of the protective layer 14 in the second region S2 towards the light-emitting surface can be increased, and the light-emitting efficiency can be improved.

[0069] In the second electrode 60 region, the current blocking layer 40 is located between the second semiconductor layer 23 and the transparent conductive layer 30. The upper surface of the second region S2 of the protective layer 14 is covered with the insulating layer 70. In some embodiments, a PVD-AlN layer is formed as the buffer layer 18 on the side surface of the protective layer 14 away from the substrate, so that the plating film effect of the buffer layer 18 on the protective layer 14 is good, the AlN layer has good adhesion, and the growth of the epitaxial structure 20 is facilitated and the growth quality of the epitaxial structure 20 is improved. The epitaxial structure 20 and other hierarchical structures are not the focus of the present application, and will not be described in detail here. The structural features of this part can be referred to other existing documents.

[0070] Again refer to Figure 7 In some embodiments, the protective layer 14 is provided in a filling and leveling manner, and the buffer layer 18 is also provided in a planar manner. After the epitaxial structure 20 and other processes are completed, the surface above the pattern structure 12 in the second region S2 of the protective layer 14 is relatively flat, which is beneficial to removing the transparent conductive layer 30 and the current blocking layer 40 remaining in this region by a wet method, reducing the influence of the remaining transparent conductive layer 30, reducing the electric leakage, and improving the overall performance of the light-emitting diode 200.

[0071] As shown in Figure 7 In some embodiments, the epitaxial structure 20 is provided in an inverted trapezoidal structure, and the epitaxial structure 20 has an inclined angle a between the side wall and the substrate 10 (the upper surface of the protective layer 14 in the figure), and the inclined angle a is an acute angle. Optionally, the range of the inclined angle a is 20°-60°, which can improve the light reflection of the side wall region of the epitaxial structure 20 and improve the light-emitting efficiency. When the structure is provided in this way, the transparent conductive layer 30 and the current blocking layer 40 remaining in the second region of the protective layer 14 are removed by acid etching, which is easy to damage the pattern structure 12. At this time, the protective layer 14 is preferably provided in a filling and leveling manner, which can better protect the integrity of the pattern structure 12.

[0072] In some embodiments, the epitaxial structure 20 is arranged in a trapezoidal or vertical structure, and the sidewall of the epitaxial structure 20 and the substrate 10 (the upper surface of the protective layer 14 in the figure) have an inclined angle α, which is a right angle or an obtuse angle. In this case, the structure of the protective layer 14 can increase the total internal reflection of the substrate 10 and improve the light emission efficiency of the light-emitting diode 200.

[0073] Combination Figure 4 See Figure 9 , Figure 9 This is a cross-sectional view of the second embodiment of the light-emitting diode in this utility model. Figure 7 Compared to the LEDs shown, in Figure 9 In the illustrated embodiment, the protective layer 14 is attached, and the buffer layer 18 is also attached. That is, both the protective layer 14 and the buffer layer 18 have an uneven, textured structure that matches the shape of the patterned structure 12. After the epitaxial structure 20 and other processes are completed, the surface above the patterned structure 12 in the second region S2 of the protective layer 14 is non-flat. The remaining transparent conductive layer 30 and current blocking layer 40 in this region are also non-flat structures. These residues can be removed using other methods, thereby increasing light reflection in the second region S2 of the protective layer 14 and improving luminous efficiency.

[0074] contrast Figure 7 and Figure 9 In some embodiments, the light-emitting surface of the flip-chip LED made of the patterned substrate 100 is located below the second surface 10b of the substrate 10. In order to reduce the blocking or absorption of the light emitted from the epitaxial structure 20 by the second surface 10b of the substrate 10 and increase the light emission below the second surface 10b, the protective layer 14 may not adopt the first DBR structure 15, and the second DBR structure 16 may not be provided below the second surface 10b of the substrate 10. In this case, the protective layer 14 may be a single layer of SiO2 in a flat-fill manner to prevent the patterned structure 12 from being damaged in subsequent processes.

[0075] In the light-emitting diode 200, the refractive index of the epitaxial structure 20 (e.g., GaN material with a refractive index of approximately 2.5) is greater than that of the substrate 10 (e.g., sapphire substrate with a refractive index of 1.7–1.8), and the refractive index of the substrate 10 is greater than that of the protective layer 14 (e.g., SiO2 with a refractive index of approximately 1.5). This configuration results in a greater difference in refractive index between the epitaxial structure 20 and the protective layer 14 compared to the difference in refractive index between the epitaxial structure 20 and the patterned substrate 100. This allows light emitted from the epitaxial structure 20 towards the substrate 10 to have a wider incident angle on the patterned substrate 100 that satisfies total internal reflection. This, in turn, increases the reflectivity of the patterned substrate 100 towards the light emitted from the epitaxial structure 20, improves the light extraction efficiency of the light-emitting diode 200, and enhances the brightness of the device.

[0076] The high-voltage LED device is composed of a plurality of small-power LEDs in series, and short circuit and electric leakage can be caused due to the influence of LED technology (such as incomplete removal of ITO). When the high-voltage LED device is made by the series connection of the aforementioned light-emitting diode 200, the material of the protective layer 14 is a light-transmitting insulating material. The continuous protective layer 14 is arranged below each light-emitting diode 200 (LED), which can prevent the direct conduction between the adjacent light-emitting diodes 200, avoid short circuit, reduce the generation of electric leakage, and improve the stability, safety and light efficiency of the high-voltage LED device.

[0077] In combination Figure 1 Referring to Figure 10 , Figure 10 is a structural schematic view of an embodiment of the patterned substrate in the utility model after the epitaxial structure is made. Further, Figure 1 is an SEM image obtained by electron beam scanning of the existing normal type light-emitting diode made of the patterned substrate, Figure 10 is an SEM image obtained by electron beam scanning of the light-emitting diode 200 made of the patterned substrate 100 in the application. From the comparison of Figure 1 and Figure 10 , it can be known that the convex pattern structure 12 on the patterned substrate 100 in the application is covered with the protective layer 14, and the top of the convex pattern structure 12 will not be corroded by the etching material in the subsequent epitaxial structure 20 growth process and the like, and the convex pattern structure 12 can be completely retained, which ensures that the reflection of the epitaxial structure 20 emitted light in the convex pattern structure 12 area can be maximized. At the same time, in the second area S2 of the protective layer 12, the convex pattern structure 12 can also be completely retained, and the light received in this area can be more reflected to the light emitting surface, which increases the light reflection of the patterned substrate 100 area, improves the light emitting efficiency of the light-emitting diode 200, and improves the brightness of the device.

[0078] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the utility model, and not to limit them; although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the utility model.

Claims

1. A light emitting diode, characterized by, At least comprising: a substrate having a first surface and a second surface arranged oppositely; a plurality of protruding pattern structures arranged at intervals above the first surface of the substrate; a protective layer arranged above the first surface and covering the plurality of protruding pattern structures and the first surface; an epitaxial structure arranged above the protective layer, comprising a first semiconductor layer, an active layer and a second semiconductor layer stacked in sequence from bottom to top; wherein the refractive index of the protective layer is less than the refractive index of the substrate.

2. The light emitting diode of claim 1, wherein, The thickness of the protective layer is not more than 2.5 microns; or the thickness of the protective layer is greater than or equal to 3 microns.

3. The light emitting diode of claim 1, wherein, On the first surface of the substrate, the protective layer is divided into a first region and a second region, and viewed from above the first surface of the substrate, the second region is located at the periphery of the first region; the epitaxial structure is located in the first region, the thickness of the protective layer in the first region is H1, the thickness of the protective layer in the second region is H2, H1>H2.

4. The light emitting diode of claim 3, wherein, The thickness difference between H1 and H2 is not more than 0.5 microns.

5. The light emitting diode of claim 3, wherein the first and second semiconductor layers are formed of a nitride semiconductor. In the second region, the thickness of the protective layer is unevenly distributed.

6. The light emitting diode of claim 1, wherein, The protective layer is a first DBR structure, and the first DBR structure is a stacked structure composed of first sub-layers and second sub-layers alternately; wherein the refractive index of the first sub-layer is less than the refractive index of the second sub-layer.

7. The light emitting diode of claim 6, wherein, In the first DBR structure, the sub-layer closest to and farthest from the first surface of the substrate is the first sub-layer, and the thickness of the first sub-layer farthest from the first surface of the substrate is greater than or equal to 200 angstroms.

8. The light emitting diode according to claim 1 or 6, wherein A second DBR structure is arranged below the second surface of the substrate, and the second DBR structure is a stacked structure composed of third sub-layers and fourth sub-layers alternately, wherein the stacked structure of the third sub-layers and the fourth sub-layers is at least one group, and the third sub-layers and the fourth sub-layers have different refractive indexes.

9. The light emitting diode of claim 1, wherein, A buffer layer is arranged between the protective layer and the epitaxial structure.

10. The light emitting diode of claim 1, wherein, The refractive index of the epitaxial structure is greater than the refractive index of the substrate, and the refractive index of the substrate is greater than the refractive index of the protective layer.

11. The light emitting diode of claim 1, wherein, The epitaxial structure has an inclined angle between the sidewall and the substrate, and the inclined angle is an acute angle.

12. A light-emitting device, characterized in that: The light-emitting diode comprises any one of claims 1 to 11.

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