Light emitting diode and light emitting device

Abstract

The application relates to the technical field of semiconductor manufacturing, in particular to a light-emitting diode which comprises a semiconductor stack, an insulating layer and a metal reflecting layer, the semiconductor stack comprises a first semiconductor layer, a light-emitting layer and a second semiconductor layer in sequence along the direction from the upper surface to the lower surface, the insulating layer is arranged on the lower surface of the semiconductor stack, the insulating layer has a first opening, the metal reflecting layer is arranged on the lower surface of the semiconductor stack and covers the insulating layer, part of the metal reflecting layer is filled in the first opening, and the vertical projection points of the edge end points of the upper surface of the insulating layer on the horizontal plane are distributed in the first line segment of the vertical projection of the edge end points of the upper surface of the metal reflecting layer on the horizontal plane. Therefore, the edge of the insulating layer in the preparation process can be prevented from having a sawtooth-shaped defect, damage can be avoided, and the quality of the light-emitting diode is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a light-emitting diode and a light-emitting device. Background Technology

[0002] A light-emitting diode (LED) is a semiconductor light-emitting element, typically made of semiconductors such as GaN, GaAs, GaP, and GaAsP. Its core is a PN junction that emits light. LEDs possess advantages such as high luminous intensity, high efficiency, small size, and long lifespan, and are considered one of the most promising light sources available today. LEDs are widely used in lighting, monitoring and command systems, high-definition broadcasting, high-end cinemas, office displays, interactive conferencing, virtual reality, and other fields.

[0003] To meet market demands, LEDs have developed ultra-high power horizontal structure chips. The high-power horizontal structure employs a thermoelectric separation design, featuring high current density, ultra-high brightness, and excellent aging performance. Packaging manufacturers typically use a high-voltage series connection for packaging, effectively expanding the light-emitting area to meet product application requirements.

[0004] Currently, the following problems exist in the fabrication of high-power horizontal structure light-emitting diodes: Due to the need to enhance light reflection, the insulating layer is usually made of two materials with different refractive indices, such as a DBR structure with alternating stacks of silicon oxide and titanium oxide. The etching rate of these two materials is different in the etching solution used in the etching process, resulting in delamination at the edge of the insulating layer, presenting a "serrated" defect. As a result, the effect is poor in the subsequent evaporation of metal electrodes. Furthermore, as the subsequent process temperature increases, the gaps at the edge of the insulating layer further increase. During the final stripping of the pad electrodes, the epitaxial layer will be lifted along the gap, or even fall off, which greatly affects the quality of the light-emitting diode.

[0005] It should be noted that the information disclosed in this background section is intended only to enhance the understanding of the overall background of the present invention, and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The present invention provides a light-emitting diode, which includes a semiconductor stack, an insulating layer and a metal reflective layer.

[0007] The semiconductor stack has opposing upper and lower surfaces, and sequentially includes a first semiconductor layer, a light-emitting layer, and a second semiconductor layer along the direction from the upper to the lower surface. An insulating layer is disposed on the lower surface of the semiconductor stack, and the insulating layer includes at least two materials with different refractive indices. The insulating layer has a first opening, which corresponds to the area below the second semiconductor layer. A metal reflective layer is disposed on the lower surface of the semiconductor stack and covers the insulating layer, with a portion of the metal reflective layer filling the first opening. The vertical projection points of the edge endpoints of the upper surface of the insulating layer onto the horizontal plane are distributed within a first line segment connecting the vertical projections of the edge endpoints of the upper surface of the metal reflective layer onto the horizontal plane.

[0008] The present invention also provides a light-emitting device, which employs any of the light-emitting diodes provided above.

[0009] An embodiment of the present invention provides a light-emitting diode and a light-emitting device. By distributing the vertical projection points of the edge endpoints of the upper surface of the insulating layer in the horizontal plane within the first line segment connecting the vertical projection points of the edge endpoints of the upper surface of the metal reflective layer in the horizontal plane, the metal reflective layer can cover the insulating layer. This can effectively avoid the problem of "serrated" defects at the edges of the insulating layer during the manufacturing process, prevent damage, and improve the quality of the light-emitting diode.

[0010] Other features and advantages of the present invention will be set forth in the following description, and some of the technical features and advantages may be apparent from the description or learned by practicing the invention. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, some of the drawings in the following description are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the structure of a light-emitting diode provided in an embodiment of the present invention;

[0013] Figure 2 yes Figure 1 A schematic diagram showing the vertical projection of the upper surface of the insulating layer onto the horizontal plane, the upper surface of the metal reflective layer onto the horizontal plane, and the lower surface of the light-emitting layer onto the horizontal plane.

[0014] Figure 3 This is a schematic diagram of the structure of a traditional light-emitting diode;

[0015] Figure 4This is a schematic diagram of a traditional light-emitting diode exhibiting epitaxial shedding.

[0016] Figure 5 This is a schematic diagram of a light-emitting diode provided in an embodiment of the present invention.

[0017] Figure label:

[0018] 12-Semiconductor stack; 121-First semiconductor layer; 122-Light emitting layer; 123-Second semiconductor layer; 14-Insulating layer; 16-Metal reflective layer; 18-Metal protective layer; 21-First electrode; 22-Second electrode; 31-First opening; 32-Second opening; 34-Conductive layer; 40-Bonding layer; 42-Carrier substrate. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] In the description of this invention, it should be understood that the terms "center," "lateral," "upper," "lower," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. Additionally, the term "comprising" and any variations thereof mean "at least comprising."

[0021] Please see Figures 1 to 5 , Figure 1 This is a schematic diagram of the structure of a light-emitting diode provided in an embodiment of the present invention. Figure 2 yes Figure 1The diagram shows the vertical projection of the line connecting the edge endpoints of the upper surface of the insulating layer 14 and the edge endpoints of the upper surface of the metal reflective layer 16 in the horizontal plane, and the lower surface of the light-emitting layer 122 in the horizontal plane. Figure 3 This is a schematic diagram of the structure of a traditional light-emitting diode. Figure 4 This is a schematic diagram of a traditional light-emitting diode exhibiting epitaxial growth. Figure 5 This is a schematic diagram of a light-emitting diode according to an embodiment of the present invention. It should be noted that... Figure 2 To make the points in the figure clearer, the length of the line segment between point E and point F has been shortened. To achieve at least one or more of the aforementioned advantages, an embodiment of the present invention provides a light-emitting diode (LED). As shown in the figure, the LED includes a semiconductor stack 12, an insulating layer 14, and a metal reflective layer 16.

[0022] The semiconductor stack 12 has opposing upper and lower surfaces, and the semiconductor stack 12 includes a first semiconductor layer 121, a light-emitting layer 122, and a second semiconductor layer 123 sequentially along the direction from the upper surface to the lower surface. That is, the light-emitting layer 122 is located between the first semiconductor layer 121 and the second semiconductor layer 123.

[0023] The first semiconductor layer 121 can be an N-type semiconductor layer, which can provide electrons to the light-emitting layer 122 under the influence of a power source. The first semiconductor layer 121 can be an electron-providing material layer through n-type doping. The N-type semiconductor layer can be doped with n-type dopants such as Si, Ge, or Sn.

[0024] The light-emitting layer 122 can be a quantum well (QW) structure. In some embodiments, the light-emitting layer 122 can also be a multiple quantum well (MQW) structure, wherein the multiple quantum well structure includes multiple quantum well layers (Wells) and multiple quantum barrier layers (Barriers) arranged alternately in a repeating manner, such as a GaN / AlGaN, InAlGaN / InAlGaN, or AlInP / AlGaInP multi-quantum well structure. Furthermore, the composition and thickness of the well layers within the light-emitting layer 122 determine the wavelength of the generated light. To improve the luminous efficiency of the light-emitting layer 122, this can be achieved by changing the depth of the quantum wells, the number of paired quantum wells and quantum barriers, the thickness, and / or other characteristics within the light-emitting layer 122.

[0025] The second semiconductor layer 123 can be a p-type semiconductor layer, which can provide holes to the light-emitting layer 122 under the influence of power. The second semiconductor layer 123 can be a hole-providing material layer by p-type doping, and the p-type semiconductor layer can be doped with p-type dopants such as Mg, Zn, Ca, Sr or Ba. The second semiconductor layer 123 can be a single-layer structure or a multi-layer structure with different compositions.

[0026] The first semiconductor layer 121, the light-emitting layer 122, and the second semiconductor layer 123 can be formed from materials such as aluminum gallium indium nitride, gallium nitride, aluminum gallium nitride, aluminum indium phosphide, aluminum gallium indium phosphide, gallium arsenide, or aluminum gallium arsenide. The first semiconductor layer 121 or the second semiconductor layer 123 includes a cladding layer that provides electrons or holes, and may include other layer materials, such as a current spreading layer, a window layer, or an ohmic contact layer, etc., configured as different multilayers depending on the doping concentration or composition content. The light-emitting layer 122 is the region that provides light radiation by providing electron-hole recombination, and different materials can be selected according to different emission wavelengths. The light-emitting layer 122 can be a periodic structure of a single quantum well or multiple quantum wells. By adjusting the composition ratio of the semiconductor materials in the light-emitting layer 122, it is desired to radiate light of different wavelengths. In this embodiment, the preferred material for the light-emitting layer 122 is aluminum gallium indium phosphide or aluminum gallium arsenide. The light-emitting layer 122 can radiate red light or infrared light. That is, the semiconductor stack 12 can radiate red light or infrared light, and the light-emitting diode can be a red light or infrared light-emitting diode.

[0027] An insulating layer 14 is disposed on the lower surface of the semiconductor stack 12. The insulating layer 14 serves both as insulation and a reflective layer, thereby improving the luminous efficiency of the light-emitting diode (LED). The insulating layer 14 comprises at least two materials with different refractive indices. Optionally, the insulating layer 14 is a DBR (Distributed Bragg Reflector) structure. A DBR structure is formed by periodically stacking thin films with different refractive indices, i.e., a periodic thin film composed of alternating high-refractive-index and low-refractive-index materials, such as silicon oxide and titanium oxide. By adjusting the refractive index, thickness, and stacking number of the individual films constituting the DBR structure, the DBR structure can achieve different transmittance and reflectance for light at different incident angles. However, this invention is not limited to this; the insulating layer 14 can also be composed of three or more layers of materials with different refractive indices. The insulating layer 14 has a first opening 31, which corresponds to the area below the second semiconductor layer 123. The insulating layer 14 can be connected to the second semiconductor layer 123. In some embodiments, a conductive layer 34 is provided at the first opening 31 for subsequent formation of better ohmic contact. This conductive layer 34 can be made of ITO or AuZn material, which facilitates voltage stability and good electrical contact with the second semiconductor layer 123. In this invention, the conductive layer 34 is distributed between the insulating layers 14, i.e., patterned, which reduces light absorption by the conductive layer 34. A metal reflective layer 16 filling the first opening 31 connects to the conductive layer 34.

[0028] A metal reflective layer 16 is disposed on the lower surface of the semiconductor stack 12 and covers the insulating layer 14. A portion of the metal reflective layer 16 fills the first opening 31 to form a good ohmic contact with the second semiconductor layer 123. The metal reflective layer 16 covers the four sidewalls and the lower surface of the insulating layer 14. Besides its electrical conduction function, the metal reflective layer 16 can also reflect light, forming an ODR (Optical Dispersion Reflection) structure together with the upper insulating layer 14 to enhance the light emission of the light-emitting diode. The metal reflective layer 16 can be a single-layer, double-layer, or multi-layer structure. The material of the metal reflective layer 16 can be selected from at least one of the group consisting of Au, Ag, Pt, and Ti. For example, the metal reflective layer 16 can be an Ag / Ti alloy metal structure, but this embodiment is not limited to this. The upper surface of the metal reflective layer 16 and the upper surface of the insulating layer 14 are located on the same horizontal plane to ensure the flatness of the structural surface. In some embodiments, the thickness of the metal reflective layer 16 can be in the range of 2000 to 6000 angstroms to improve the reflective effect of the metal reflective layer 16 and enhance the protection of the insulating layer 14.

[0029] The vertical projection points of the edge endpoints of the upper surface of the insulating layer 14 onto the horizontal plane are distributed within the first line segment connecting the vertical projections of the edge endpoints of the upper surface of the metal reflective layer 16 onto the horizontal plane. Specifically, as shown... Figure 1 and Figure 2As shown, the vertical projection points of the edge endpoints of the upper surface of the insulating layer 14 onto the horizontal plane are points C and D, and the vertical projection points of the edge endpoints of the upper surface of the metal reflective layer 16 onto the horizontal plane are points A and B. The line segment connecting points A and B is the first vertical projection line segment. Points C and D both fall within the first vertical projection line segment, so that the metal reflective layer 16 is connected to the outermost side of the insulating layer 14, completely covering the insulating layer 14. This effectively avoids the problem of "jagged" defects appearing at the edges of the insulating layer 14 during the manufacturing process, improving the quality of the light-emitting diode. Conversely... Figure 3 The conventional light-emitting diode (LED) shown has its outermost insulating layer exposed. This insulating layer is made of two materials with different refractive indices. Due to the different etching rates of these two materials by the etching solution during the etching process, delamination occurs at the edge of the insulating layer, resulting in a "serrated" defect. The metal protective layer 18 cannot adequately cover the insulating layer. As the subsequent process temperature increases, the gaps at the edge of the insulating layer further widen. During the final stripping of the pad electrodes, the epitaxial layer is lifted along these gaps, causing epitaxial detachment. For a more detailed comparison, see the reference section. Figure 4 and Figure 5 , Figure 4 Traditional light-emitting diodes (LEDs) exhibited significant detachment issues, while Figure 5 With the aforementioned improvements, the LED of the present invention shows no visible peeling. According to experimental data, the design of the present invention can improve the epitaxial yield by 15%-30%.

[0030] In some embodiments, the minimum distance between the vertical projection point and the endpoint of the first vertical projection line segment is 5~10μm. That is, the distance from point C to point A is 5~10μm, and the distance from point D to point B is 5~10μm. If this distance range is too large (e.g., greater than 10μm), which means that the insulating layer 14 is reduced too much, the reflective effect of the insulating layer 14 will be deteriorated, thereby affecting the light output brightness of the light-emitting diode. If the distance range is too small (e.g., less than 5μm), the width of the metal reflective layer 16 will be too narrow, reducing its protective effect against solution erosion, resulting in a poorer blocking effect and still posing a risk of structural detachment.

[0031] In some embodiments, the lower surface of the light-emitting layer 122 is located within the first vertical projection line segment on the horizontal plane, and the vertical projection point is located outside the first vertical projection line segment. Specifically, as shown... Figure 1 and Figure 2As shown, the first vertical projection line segment of the lower surface of the light-emitting layer 122 on the horizontal plane refers to the line segment connecting points E and F. That is, the EF line segment is inside the AB line segment, while points C and D are outside the EF line segment. This allows the insulating layer 14 to play a more effective role in blocking and reflecting current. If points C and D fall inside the EF line segment, the current blocking effect of the insulating layer 14 will be worse, the reflection effect will be worse, and the optical performance of the light-emitting diode will be reduced. Furthermore, if the insulating layer 14 is to be shrunken inside the semiconductor stack 12 (i.e., points C and D are located inside the EF line segment), an additional process is required to remove the excess semiconductor stack 12, making the process more complicated and unfavorable for production.

[0032] In some embodiments, the light-emitting diode further includes a metal protective layer 18, a first electrode 21, and a second electrode 22.

[0033] The metal protective layer 18 covers the metal reflective layer 16 and also serves to conduct electricity. The metal protective layer 18 can be a single layer, double layer, or multi-layer structure, and the material of the metal protective layer 18 can be selected from at least one of the group consisting of Ti, Pt, and Au. For example, the metal protective layer 18 is a multi-layer stacked metal structure of Ti / Pt / Au.

[0034] The second semiconductor layer 123 has a second opening 32 that exposes the metal protective layer 18. The second electrode 22 is connected to the metal protective layer 18 through the second opening 32 to achieve electrical connection with the second semiconductor layer 123. The first electrode 21 is connected to the first semiconductor layer 121. The second electrode 22 is spaced apart from the semiconductor stack 12 to avoid short circuits. The first electrode 21 may include an extended electrode to facilitate current spread and improve the optical performance of the light-emitting diode.

[0035] In some embodiments, the upper surface of the metal protective layer 18 and the lower surface of the second semiconductor layer 123 are flush. This flushing is achieved by the metal reflective layer 16 covering the insulating layer 14, thereby reducing the height difference between the first electrode 21 and the second electrode 22, which is beneficial for subsequent wire bonding processes of the electrodes.

[0036] In some embodiments, the light-emitting diode further includes a bonding layer 40 and a carrier substrate 42. The bonding layer 40 is disposed on the lower surface of the metal protective layer 18. The carrier substrate 42 is disposed on the lower surface of the bonding layer 40.

[0037] An embodiment of the present invention also provides a light-emitting device, which may employ a light-emitting diode from any of the foregoing embodiments.

[0038] In summary, the light-emitting diode and light-emitting device provided by one embodiment of the present invention distribute the vertical projection points of the edge endpoints of the upper surface of the insulating layer 14 in the horizontal plane within the first line segment connecting the vertical projections of the edge endpoints of the upper surface of the metal reflective layer 16 in the horizontal plane. This allows the metal reflective layer 16 to cover the insulating layer 14, effectively avoiding the problem of "serrated" defects at the edges of the insulating layer 14 during the manufacturing process, preventing damage, and improving the quality of the light-emitting diode.

[0039] Furthermore, those skilled in the art should understand that although many problems exist in the prior art, each embodiment or technical solution of the present invention can be improved in only one or a few aspects, without necessarily solving all the technical problems listed in the prior art or the background art simultaneously. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as a limitation on that claim.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions 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 diode, characterized in that: The light-emitting diode includes: A semiconductor stack having opposing upper and lower surfaces, wherein the semiconductor stack comprises, in sequence along the direction from the upper surface to the lower surface, a first semiconductor layer, a light-emitting layer, and a second semiconductor layer; An insulating layer is disposed on the lower surface of the semiconductor stack, the insulating layer comprising at least two materials with different refractive indices, the insulating layer having a first opening corresponding to the area below the second semiconductor layer; A metal reflective layer is disposed on the lower surface of the semiconductor stack and covers the insulating layer, with a portion of the metal reflective layer filling the first opening; Wherein, the vertical projection points of the edge endpoints of the upper surface of the insulating layer in the horizontal plane are distributed within the first line segment of the vertical projection of the edge endpoints of the upper surface of the metal reflective layer in the horizontal plane; the minimum distance between the vertical projection points and the endpoints of the first line segment of the vertical projection is 5~10μm. The light-emitting diode further includes a metal protective layer, a first electrode, and a second electrode. The metal protective layer covers the metal reflective layer. The second semiconductor layer has a second opening that exposes the metal protective layer. The second electrode is connected to the metal protective layer through the second opening. The first electrode is connected to the first semiconductor layer.

2. The light-emitting diode according to claim 1, characterized in that: The lower surface of the light-emitting layer is located within the first vertical projection line segment on the horizontal plane, and the vertical projection point is located outside the first vertical projection line segment.

3. The light-emitting diode according to claim 1, characterized in that: A conductive layer is provided at the first opening.

4. The light-emitting diode according to claim 3, characterized in that: The light-emitting diode further includes a bonding layer and a carrier substrate. The bonding layer is disposed on the lower surface of the metal protective layer, and the carrier substrate is disposed on the lower surface of the bonding layer.

5. The light-emitting diode according to claim 1, characterized in that: The thickness of the metal reflective layer ranges from 2000 angstroms to 6000 angstroms.

6. The light-emitting diode according to claim 1, characterized in that: The upper surface of the metal protective layer is flush with the lower surface of the second semiconductor layer.

7. The light-emitting diode according to claim 1, characterized in that: The material of the metal reflective layer is selected from at least one of the group consisting of Au, Ag, Pt and Ti.

8. The light-emitting diode according to claim 1, characterized in that: The material of the metal protective layer is selected from at least one of the group consisting of Ti, Pt, and Au.

9. The light-emitting diode according to claim 1, characterized in that: The semiconductor stack radiates red or infrared light.

10. The light-emitting diode according to claim 1, characterized in that: The insulating layer adopts a DBR structure.

11. A light-emitting device, characterized in that: The light-emitting device is a light-emitting diode as described in any one of claims 1 to 10.

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