Light emitting element and method for manufacturing the same

Abstract

The present invention relates to the field of semiconductor manufacturing technology, and in particular to a light-emitting element and a method for manufacturing the same. The light-emitting element includes a substrate; an epitaxial stack having a first surface and a second surface relative to each other; a transparent bonding layer located between the first surface of the epitaxial stack and the substrate, and the transparent bonding layer includes at least one dense layer made of a transparent oxide; wherein a gap is formed on the transparent bonding layer, and the gap extends from the transparent bonding layer surface close to the epitaxial stack to the transparent bonding layer surface away from the epitaxial stack, and does not reach the transparent bonding layer surface away from the epitaxial stack. The light-emitting element provided by the present invention reduces the internal stress of the transparent oxide itself by setting a gap on the transparent bonding layer, thereby effectively reducing the cracking and peeling phenomenon between the interface of the epitaxial stack and the transparent bonding layer caused by thermal mismatch in the subsequent chip annealing process.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a light-emitting element and a manufacturing method thereof. Background Art

[0002] Light Emitting Diode (LED) is a semiconductor light-emitting element, usually made of semiconductors such as GaN, GaAs, GaP, GaAsP, etc. Its core is a PN junction with light-emitting characteristics. Under forward voltage, electrons are injected from the N region into the P region, and holes are injected from the P region into the N region. The electrons and holes recombine to make the light-emitting diode emit light. LED has the advantages of high luminous intensity, high efficiency, small size, and long service life, and is widely used in various fields.

[0003] Existing light-emitting elements generally bond the epitaxial layer to the substrate through bonding technology, among which the bonding technology of bonding the epitaxial layer to the substrate using transparent oxide as the bonding layer is widely used in light-emitting diodes. However, the chip source obtained by this bonding method will have abnormal explosion points in the subsequent chip annealing process, that is, the interface between the epitaxial layer and the transparent oxide will crack and peel off, which will affect the reliability of the light-emitting diode. Therefore, how to avoid abnormal explosion points in the chip source in the subsequent chip process has become one of the technical problems that technicians in this field need to solve urgently. Summary of the invention

[0004] The present invention provides a light-emitting element, which includes: a substrate;

[0005] an epitaxial stack having opposing first and second surfaces;

[0006] a transparent bonding layer, located between the first surface of the epitaxial stack and the substrate, the transparent bonding layer comprising at least one dense layer made of a transparent oxide;

[0007] A gap is formed on the transparent bonding layer, and the gap extends from the transparent bonding layer surface close to the epitaxial stack to the transparent bonding layer surface away from the epitaxial stack, and does not reach the transparent bonding layer surface away from the epitaxial stack.

[0008] In some embodiments, the height of the gap from the surface of the transparent bonding layer on the side away from the epitaxial stack is greater than or equal to 0.8 μm.

[0009] In some embodiments, the first surface is a rough surface, and the rough surface is a randomly roughened surface or a regularly patterned surface, and the maximum depth of the roughening is between 0.5 and 1.0 μm.

[0010] In some embodiments, the transparent bonding layer includes at least two dense layers formed by stacking transparent oxides; wherein the density of the dense layer directly contacting the epitaxial stack is higher than the density of the dense layer not directly contacting the epitaxial stack.

[0011] In some embodiments, the transparent bonding layer includes a first dense layer and a second dense layer made of transparent oxide, and the second dense layer is formed on the first dense layer; the first dense layer is in contact with the epitaxial stack, and the second dense layer is in contact with the substrate, and the density of the first dense layer is higher than the density of the second dense layer.

[0012] In some embodiments, the first dense layer and the second dense layer are made of the same or different materials.

[0013] In some embodiments, a thickness ratio of the first dense layer to the second dense layer ranges from 1:100 to 1:5.

[0014] In some embodiments, the transparent bonding layer has a thickness of 2-5 μm.

[0015] In some embodiments, the transparent bonding layer is made of insulating material or conductive material.

[0016] In some embodiments, the transparent bonding layer is formed on the first surface of the epitaxial stack by a chemical deposition process or a coating process.

[0017] In some embodiments, the surface of the transparent bonding layer is polished, the polishing amount is greater than or equal to 0.8 μm and less than or equal to 1.5 μm, and the surface roughness is less than or equal to 10 nm.

[0018] In some embodiments, the light emitting element further includes an insulating protection layer, and the insulating protection layer at least covers the surface and sidewalls of the epitaxial stack.

[0019] In some embodiments, the insulating protection layer is a transparent insulating layer.

[0020] In some embodiments, the light-emitting element also includes: a first welding electrode and a second welding electrode, both located on the second surface of the epitaxial stack; the epitaxial stack includes a first semiconductor layer, an active layer and a second semiconductor layer, and the active layer is located between the first semiconductor layer and the second semiconductor layer; the first welding electrode is electrically connected to the first semiconductor layer; the second welding electrode is electrically connected to the second semiconductor layer.

[0021] In some embodiments, the light emitting element is a red light emitting element or an infrared light emitting element.

[0022] The present invention also provides a method for manufacturing a light emitting element, comprising the steps of:

[0023] Providing an epitaxial stack grown on a growth substrate, the epitaxial stack comprising a first semiconductor layer, an active layer, and a second semiconductor layer;

[0024] Roughening one surface of the epitaxial stack of the light emitting element, and then depositing a transparent bonding layer on the roughened surface of the epitaxial stack by a coating process, so that the transparent bonding layer has a gap; the gap does not penetrate the opposite surface of the transparent bonding layer;

[0025] After a polishing process, the epitaxial stack is bonded and transferred to a substrate and the growth substrate is removed to expose the epitaxial layer stack.

[0026] In some embodiments, the method further includes the steps of: making an insulating protective layer to cover the surface and side walls of the epitaxial stack; making a first welding electrode and a second welding electrode, and electrically connecting them to the first type semiconductor layer and the second type semiconductor layer respectively.

[0027] A light-emitting element provided by an embodiment of the present invention reduces the internal stress of the transparent oxide itself by setting a gap on the transparent bonding layer, thereby effectively reducing the cracking and peeling phenomenon between the epitaxial stack and the transparent bonding layer interface caused by thermal mismatch in the subsequent chip annealing process.

[0028] Other features and advantages of the present invention will be set forth in the following description, and in part will be apparent from the description, or may be learned by practicing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 is a schematic structural diagram of a light-emitting element in an embodiment provided by the present invention;

[0031] Figure 2 It is a schematic structural diagram of a face-up or flip-down structure light-emitting element provided by the present invention;

[0032] Figure 3 is a schematic structural diagram of a vertical structure light-emitting element provided by the present invention;

[0033] Figures 4 to 11 It is a schematic diagram of the structure of the light-emitting element in different manufacturing stages shown in the embodiment of the present invention.

[0034] Reference numerals:

[0035] 10 - substrate; 20 - epitaxial stack; 30 - transparent bonding layer; 31 - gap; 21 - first semiconductor layer; 22 - active layer; 23 - second semiconductor layer; 40 - insulating protection layer; 50 - first welding electrode; 60 - second welding electrode; 70 - growth substrate. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; the technical features designed in different implementation modes of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0037] In the description of the present invention, it should be understood that the terms "center", "lateral", "up", "down", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more. In addition, the term "including" and any variation thereof all mean "at least including".

[0038] See also Figure 1 , Figure 1 1 is a schematic diagram of a light emitting element in an embodiment of the present invention. To achieve at least one of the above advantages or other advantages, an embodiment of the present invention provides a light emitting element, as shown in the figure, the light emitting element may include a substrate 10, an epitaxial stack 20 and a transparent bonding layer 30.

[0039] The substrate 10 has sufficient strength to mechanically support the epitaxial stack 20 and can transmit light emitted from the semiconductor epitaxial stack 20. Specifically, the substrate 10 can be a transparent substrate, and the material of the transparent substrate includes inorganic materials or III-V semiconductor materials. Inorganic materials include silicon carbide (SiC), germanium (Ge), sapphire, lithium aluminate (LiAlO2), zinc oxide (ZnO), glass or quartz. III-V semiconductor materials include indium phosphide (InP), gallium phosphide (GaP), gallium nitride (GaN), and aluminum nitride (AlN) materials.

[0040] The epitaxial stack 20 has a first surface and a second surface opposite to each other. In this embodiment, the first surface and the second surface may correspond to the upper surface and the lower surface of the epitaxial stack 20, respectively. The epitaxial stack 20 may be manufactured using an existing epitaxial method, such as metal organic chemical vapor deposition (MOCVD), molecular beam deposition (MBE), or hydride vapor deposition (HVPE).

[0041] Please refer to Figure 1 In this embodiment, the transparent bonding layer 30 is located between the first surface of the epitaxial stack 20 and the substrate 10, wherein the transparent bonding layer 30 is formed on the first surface of the epitaxial stack 20 by a chemical deposition process or a coating process. Preferably, the thickness of the transparent bonding layer 30 is 2-5 μm.

[0042] The transparent bonding layer 30 includes at least one dense layer made of transparent oxide. Specifically, the transparent bonding layer 30 can be a single-layer structure or a multi-layer structure, and the number of bonding layers of the multi-layer structure is set according to actual needs. For example, the transparent bonding layer 30 may include a first bonding layer close to the epitaxial stack 20 and a second bonding layer away from the epitaxial stack 20. In one embodiment of the present invention, the first bonding layer is adjacent to the epitaxial stack 20, and the second bonding layer is adjacent to the substrate 10. The first bonding layer and the second bonding layer are sequentially formed on the epitaxial stack 20 to form the transparent bonding layer 30. For example, the first bonding layer is a transparent conductive layer that can play a role in current expansion, and the second bonding layer is a bonding material layer that can play a role in bonding to the substrate 10. Both materials are the same or different materials containing transparent oxide.

[0043] Optionally, the material of the transparent bonding layer 30 may be an insulating material and / or a conductive material. The insulating material includes but is not limited to aluminum oxide (Al2O3), silicon oxide (SiO x ), titanium oxide (TiO2), tantalum oxide (Ta2O5), silicon nitride (SiN x ) etc. The conductive material includes but is not limited to indium tin oxide (ITO), indium oxide (InO), tin oxide (SnO), cadmium tin oxide (CTO), antimony tin oxide (ATO), aluminum zinc oxide (AZO), zinc tin oxide (ZTO), zinc oxide (ZnO), indium zinc oxide (IZO), gallium zinc oxide (GZO), etc., and may also be the same material or a combination of the above materials. When the transparent bonding layer 30 is made of conductive material and contacts the epitaxial stack 20, it can act as a current spreading layer, improve the effect of current spreading, and enhance the uniformity of current distribution.

[0044] like Figure 1As shown, in this embodiment, a gap 31 is formed on the transparent bonding layer 30, and the gap 31 extends from the surface of the transparent bonding layer 30 close to the epitaxial stack 20 to the surface of the transparent bonding layer 30 away from the epitaxial stack 20, and does not reach the surface of the transparent bonding layer 30 away from the epitaxial stack 20. Through the above arrangement, while ensuring the bonding quality, the bonding yield of the component can be effectively improved. And the experiment shows that the transparent oxide with the gap 31 as the bonding layer can effectively reduce the internal stress of the transparent oxide itself, and reduce the cracking and peeling phenomenon between the epitaxial stack 20 and the transparent bonding layer 30 interface caused by thermal mismatch in the subsequent chip annealing process, thereby further improving the reliability of the light-emitting element manufacturing.

[0045] In some embodiments, the first surface is a rough surface, that is, the epitaxial stack 20 close to the substrate 10 is a rough surface, and the rough surface is a random roughened surface or a regular patterned surface, which is not limited here, and the maximum depth of the roughening is between 0.5 and 1.0 μm. When light passes through the transparent bonding layer 30 and the first surface, the occurrence of total reflection can be reduced.

[0046] Among them, the gap 31 can be produced by evaporating the transparent bonding layer 30 on the rough surface. Specifically, under the premise of not affecting the bonding strength and bonding stability, the density of the gap 31 can be selected according to the actual needs by adjusting the roughness of the rough surface to select a suitable density, and its shape, height, and size can be adjusted according to the actual transparent bonding layer 30 and the specific parameters of the rough surface manufacturing process. Through a limited number of experiments, a gap 31 that is more conducive to reducing its internal stress can be obtained.

[0047] In this embodiment, after the transparent bonding layer 30 is formed, the surface of the transparent bonding layer 30 needs to be polished to improve the flatness of the surface of the transparent bonding layer 30. Preferably, the polishing amount is set to be greater than or equal to 0.8 μm and less than or equal to 1.5 μm, and the surface roughness is set to be less than or equal to 10 nm.

[0048] Furthermore, considering that the transparent bonding layer 30 will be thinned after the polishing process, the height of the gap 31 from the surface of the transparent bonding layer 30 on the side away from the epitaxial stack 20 will be reduced. In order to prevent the gap 31 from reaching the surface of the transparent bonding layer 30 on the side away from the epitaxial stack 20 after the polishing process, when forming the transparent bonding layer 30, a certain height of the transparent bonding layer 30 may be reserved on the basis of the required height. Preferably, the reserved height may be: the height of the gap 31 from the surface of the transparent bonding layer 30 on the side away from the epitaxial stack 20 is greater than or equal to 0.8 μm.

[0049] In some embodiments, the transparent bonding layer 30 includes at least two dense layers formed by stacking transparent oxides; wherein the density of the dense layer in direct contact with the epitaxial stack 20 is higher than the density of the dense layer not in direct contact with the epitaxial stack 20. Such a configuration enables the dense layer in direct contact with the epitaxial stack 20 to have higher adhesion, and while not affecting the bonding strength and bonding stability, it can ensure that the adhesion between the epitaxial stack 20 and the substrate 10 is effectively improved when the epitaxial stack 20 and the substrate 10 are bonded together, thereby improving the reliability of the formed light-emitting element.

[0050] Furthermore, the transparent bonding layer 30 includes a first dense layer and a second dense layer made of transparent oxide, the second dense layer is formed on the first dense layer; the first dense layer is in contact with the epitaxial stack 20, the second dense layer is in contact with the substrate 10, and the density of the first dense layer is higher than that of the second dense layer. The first dense layer and the second dense layer are formed by a plasma enhanced chemical vapor deposition process. Specifically, in the process of forming the dense layer by the plasma enhanced chemical vapor deposition process, the adhesion of the dense layer can also be improved by changing the high frequency power and the low frequency power. The materials of the first dense layer and the second dense layer can be the same or different.

[0051] Preferably, the thickness of the first dense layer is smaller than that of the second dense layer. More preferably, the thickness ratio of the first dense layer to the second dense layer is in the range of 1:100 to 1:5, so as to further ensure the adhesion thereof and meet the subsequent process requirements.

[0052] In some embodiments, see Figure 2 The light emitting element further includes: a first welding electrode 50, a second welding electrode 60, and an insulating protective layer 40, all of which are located on the second surface of the epitaxial stack 20. The insulating protective layer 40 at least covers the surface and sidewalls of the epitaxial stack 20. Optionally, the insulating protective layer 40 is a transparent insulating layer, specifically Al2O3, TiO2, SiO2, SiN, etc., the same material or a combination of materials.

[0053] The epitaxial stack 20 includes a first semiconductor layer 21, an active layer 22 and a second semiconductor layer 23, wherein the active layer 22 is located between the first semiconductor layer 21 and the second semiconductor layer 23. The first semiconductor layer 21 and the second semiconductor layer 23 have different conductivity types, electrical properties, polarities or are doped with elements to provide electrons or holes.

[0054] In this embodiment, the first semiconductor layer 21 may be a P-type semiconductor layer, which may provide holes to the active layer 22 under the action of a power source. In some embodiments, the first semiconductor layer 21 includes a P-type doped AlInP layer, and the doping may be Mg, C, etc. In some embodiments, the first semiconductor layer 21 includes a P-type doped nitride layer. The P-type doped nitride layer may include one or more P-type impurities of group II elements. The P-type impurities may include one or a combination of Mg, Zn, and Be. The first semiconductor layer 21 may be a single-layer structure or a multi-layer structure, and the multi-layer structure may have different compositions.

[0055] The active layer 22 may be a quantum well structure. In some embodiments, the active layer 22 may also be a multiple quantum well structure, wherein the multiple quantum well structure includes multiple quantum well layers and multiple quantum barrier layers alternately arranged in a repeated manner, for example, a multiple quantum well structure of AlGaInP / GaInP, GaN / AlGaN, InAlGaN / InAlGaN or InGaN / AlGaN. In addition, the composition and thickness of the well layer in the active layer 22 determine the wavelength of the generated light. In order to improve the luminous efficiency of the active layer 22, it can be achieved by changing the depth of the quantum well, the number of layers, thickness and / or other features of the paired quantum wells and quantum barriers in the active layer 22.

[0056] The second semiconductor layer 23 may be an N-type semiconductor layer, which may provide electrons to the active layer 22 under the action of a power source. The second semiconductor layer 23 may include an N-type doped nitride layer, a phosphide layer or an arsenide layer. The N-type doped nitride layer, the phosphide layer or the arsenide layer may include one or more N-type impurities of group IV elements. The N-type impurities may include one or a combination of Si, Ge, Sn, but the embodiments of the present disclosure are not limited thereto. In some other embodiments, the second semiconductor layer 23 may also be a single layer or a multilayer structure.

[0057] It should be noted that the configuration of the epitaxial stack 20 is not limited thereto, and other functional structural layers that have an optimizing effect on the performance of the light-emitting element may be selected according to actual needs.

[0058] Specifically, the insulating protective layer 40 is provided with openings corresponding to the first welding electrode 50 and the second welding electrode 60, respectively. The first welding electrode 50 passes through the corresponding opening on the insulating protective layer 40 to be electrically connected to the first semiconductor layer 21, and the second welding electrode 60 passes through the corresponding opening on the insulating protective layer 40 to be electrically connected to the second semiconductor layer 23.

[0059] In some optional embodiments, the light emitting element is not limited to a red light emitting element or an infrared light emitting element.

[0060] It should be noted that the light emitting element provided by the present invention can be any light emitting diode with a face-up or flip-down structure using oxide as a bonding layer. Figure 2 As shown, it can also be a light-emitting diode of any vertical structure using oxide as a bonding layer. For details, please refer to Figure 3 As shown, no limitation is made here. Further, the light emitting element may preferably adopt, for example, a small-sized flip-chip light emitting diode, specifically a mini flip-chip light emitting diode. The size of the mini flip-chip light emitting diode may be between 90000 μm and 10000 μm. 2 Within, its length and width are 100μm to 300μm, and its height is 40μm to 100μm.

[0061] Figures 4 to 11 1 is a schematic diagram of a light-emitting element in different manufacturing stages according to an embodiment of the present invention. The present invention also provides a method for manufacturing a light-emitting element, comprising the following steps:

[0062] Please refer to Figure 4 , providing an epitaxial stack 20 grown on a growth substrate 70, the epitaxial stack 20 comprising a first semiconductor layer 21, an active layer 22, and a second semiconductor layer 23; the epitaxial stack 20 can be grown on the growth substrate 70 using existing known methods, such as metal organic chemical vapor deposition (MOCVD), molecular beam deposition (MBE) or hydride vapor phase deposition (HVPE) and other technologies.

[0063] Please refer to Figure 5 A surface of the light emitting element epitaxial stack 20 is roughened, and the roughening process can be carried out by etching, mechanical grinding, etc. The surface can be randomly roughened or regularly patterned, and the maximum depth of the roughening is between 0.5 and 1.0 μm.

[0064] Please refer to Figure 6 , a transparent bonding layer 30 is deposited on the roughened surface of the epitaxial stack 20 through a coating process, so that the transparent bonding layer 30 has a gap 31; the gap 31 does not penetrate the opposite surface of the transparent bonding layer 30.

[0065] Please refer to Figure 7 After a polishing process, the epitaxial stack 20 is bonded and transferred to the substrate 10 and the growth substrate 70 is removed to expose the epitaxial stack. The polishing amount of the polishing process is set to be greater than or equal to 0.8 μm and less than or equal to 1.5 μm, and the surface roughness is set to be less than or equal to 10 nm.

[0066] According to the above process, the obtained structure can be applied to face-up light-emitting elements, flip-down light-emitting elements, and vertical light-emitting elements, and the subsequent production steps can be refined according to the structure of the actual light-emitting element.

[0067] Further, here, taking a face-up or flip-down light-emitting element as an example, the epitaxial layer stack includes a first semiconductor layer 21, an active layer 22, and a second semiconductor layer 23. After the epitaxial layer stack 20 is bonded and transferred to the substrate 10 through a transparent bonding layer 30, the following steps are also included:

[0068] Please refer to Figure 8 , Fig. 9 , a P electrode is arranged on the first semiconductor layer 21, and then a portion of the first semiconductor layer 21 and the active layer 22 is etched away by a mask method, an N electrode is arranged on the exposed second semiconductor layer 23, and the epitaxial portion of a certain horizontal width of the periphery is further removed to expose a portion of the transparent bonding layer 30, so as to form a cutting path;

[0069] Please refer to Fig.10 , forming an insulating protection layer 40, and making the insulating protection layer 40 cover the surface and sidewalls of the epitaxial layer and the cutting road;

[0070] Please refer to Fig.11 , through holes are formed on the insulating protection layer 40 above the first semiconductor layer 21 and the second semiconductor layer 23, and a first welding electrode 50 and a second welding electrode 60 are made, and then contact the first semiconductor layer 21 and the second semiconductor layer 23 through the through holes.

[0071] In summary, compared with the prior art, the advantage of the light-emitting element provided by the present invention is that by setting a gap on the transparent bonding layer, the internal stress of the transparent oxide itself is reduced, thereby effectively reducing the cracking and peeling phenomenon between the epitaxial stack and the transparent bonding layer interface caused by thermal mismatch in the subsequent chip annealing process.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A light emitting element, characterized in that: The light emitting element comprises: substrate; an epitaxial stack having opposing first and second surfaces; a transparent bonding layer, located between the first surface of the epitaxial stack and the substrate, the transparent bonding layer comprising at least one dense layer made of a transparent oxide; A gap is formed on the transparent bonding layer, and the gap extends from the transparent bonding layer surface close to the epitaxial stack to the transparent bonding layer surface away from the epitaxial stack, and does not reach the transparent bonding layer surface away from the epitaxial stack.

2. The light emitting element according to claim 1, characterized in that: The height of the gap from the surface of the transparent bonding layer on the side away from the epitaxial stack is greater than or equal to 0.8 μm.

3. The light emitting element according to claim 1, wherein: The first surface is a rough surface, and the rough surface is a randomly roughened surface or a regularly patterned surface, and the maximum depth of the roughening is between 0.5 and 1.0 μm.

4. The light emitting element according to claim 1, characterized in that: The transparent bonding layer includes at least two dense layers formed by stacking transparent oxides; wherein the density of the dense layer directly in contact with the epitaxial stack is higher than the density of the dense layer not in direct contact with the epitaxial stack.

5. The light emitting element according to claim 4, characterized in that: The transparent bonding layer includes a first dense layer and a second dense layer made of transparent oxide, wherein the second dense layer is formed on the first dense layer; the first dense layer contacts the epitaxial stack, and the second dense layer contacts the substrate, and the density of the first dense layer is higher than that of the second dense layer.

6. The light emitting element according to claim 5, characterized in that: The first dense layer and the second dense layer are made of the same or different materials.

7. The light emitting element according to claim 5, characterized in that: The thickness ratio of the first dense layer to the second dense layer is in the range of 1:100 to 1:

5.

8. The light emitting element according to claim 1, characterized in that: The thickness of the transparent bonding layer is 2-5 μm.

9. The light emitting element according to claim 1, characterized in that: The transparent bonding layer is made of insulating material or conductive material.

10. The light emitting element according to claim 3, characterized in that: The transparent bonding layer is formed on the first surface of the epitaxial stack by a chemical deposition process or a coating process.

11. The light emitting element according to claim 10, characterized in that: The surface of the transparent bonding layer is polished, the polishing amount is greater than or equal to 0.8 μm and less than or equal to 1.5 μm, and the surface roughness is less than or equal to 10 nm.

12. The light emitting element according to claim 1, characterized in that: The light emitting element further includes an insulating protection layer, and the insulating protection layer at least covers the surface and side walls of the epitaxial stack.

13. The light emitting element according to claim 12, characterized in that: The insulating protection layer is a transparent insulating layer.

14. The light emitting element according to claim 1, characterized in that: The light-emitting element also includes: a first welding electrode and a second welding electrode, both located on the second surface of the epitaxial stack; the epitaxial stack includes a first semiconductor layer, an active layer and a second semiconductor layer, and the active layer is located between the first semiconductor layer and the second semiconductor layer; the first welding electrode is electrically connected to the first semiconductor layer; and the second welding electrode is electrically connected to the second semiconductor layer.

15. The light emitting element according to any one of claims 1 to 14, characterized in that: The light emitting element is a red light emitting element or an infrared light emitting element.

16. A method for manufacturing a light emitting element, characterized in that: Includes steps: Providing an epitaxial stack grown on a growth substrate, the epitaxial stack comprising a first semiconductor layer, an active layer, and a second semiconductor layer; Roughening one surface of the epitaxial stack of the light emitting element, and then depositing a transparent bonding layer on the roughened surface of the epitaxial stack by a coating process, so that the transparent bonding layer has a gap; the gap does not penetrate the opposite surface of the transparent bonding layer; After a polishing process, the epitaxial stack is bonded and transferred to a substrate and the growth substrate is removed to expose the epitaxial layer stack.

17. The method for manufacturing a light emitting element according to claim 16, characterized in that: Also includes the steps: Making an insulating protective layer to cover the surface and sidewalls of the epitaxial stack; A first welding electrode and a second welding electrode are manufactured and electrically connected to the first type semiconductor layer and the second type semiconductor layer respectively.

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