Light-emitting element and light-emitting device
By designing an insulating layer through-hole connection electrode structure in the LED light-emitting element and using a reflective die-bonding substrate, the problems of low wire bonding reliability and low light extraction efficiency were solved, achieving higher brightness and light extraction efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TIANJIN SANAN OPTOELECTRONICS
- Filing Date
- 2022-12-28
- Publication Date
- 2026-06-16
Smart Images
Figure CN115799426B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor devices and apparatus, and particularly to a light-emitting element and a light-emitting device. Background Technology
[0002] LEDs are widely used in the lighting industry due to their high brightness and low energy consumption. For horizontally structured light-emitting elements, the wire bonding structure is a crucial component affecting their optical and electrical performance. Factors influencing wire bonding reliability include: 1. Surface flatness of the bonding section; 2. Effective dispersion of impact forces during the bonding process. Factors affecting light extraction efficiency include: 1. Shielding of the bonding electrodes used for encapsulation; 2. Reflection at interfaces of materials with different refractive indices during light output; 3. Absorption of light by various materials during light output.
[0003] To address the aforementioned shortcomings of LEDs, it is essential to provide a solution that can effectively improve the reliability of LED wire bonding while simultaneously enhancing its light extraction efficiency. Summary of the Invention
[0004] In view of the above-mentioned defects of LEDs in the prior art, the present invention provides a light-emitting element and a light-emitting device to solve one or more of the above problems.
[0005] An embodiment of the present invention provides a light-emitting element, comprising:
[0006] An epitaxial layer, the epitaxial layer comprising at least a semiconductor layer of a first conductivity type, an active layer and a semiconductor layer of a second conductivity type stacked sequentially, the epitaxial layer having a first mesa, the first mesa exposing the semiconductor layer of the first conductivity type;
[0007] An insulating layer is formed on the epitaxial layer, and the insulating layer has through holes;
[0008] An electrode structure includes a first electrode electrically connected to a semiconductor layer of the first conductivity type and a second electrode electrically connected to a semiconductor layer of the second conductivity type.
[0009] The electrode structure includes a wire bonding portion and at least one connecting portion. The wire bonding portion is located above the insulating layer, the connecting portion is located at the edge of the wire bonding portion, and the through hole penetrating the insulating layer extends toward the epitaxial layer.
[0010] Optionally, the horizontal projected area of the bonding portion on the epitaxial layer is greater than the horizontal projected area of the connecting portion on the epitaxial layer.
[0011] Optionally, the horizontal projection of the bonding portion on the epitaxial layer does not coincide with the horizontal projection of the connecting portion on the epitaxial layer.
[0012] Optionally, the insulating layer is an insulating reflective layer, which is a single-layer structure or a multi-layer structure formed by repeatedly stacking two layers of material.
[0013] Optionally, the horizontal projected area of each of the electrode structures on the epitaxial layer accounts for 1% to 30% of the horizontal projected area of the epitaxial layer.
[0014] Optionally, a current spreading layer is further formed above the epitaxial layer. The current spreading layer is connected to the connecting portion. The current spreading layer is linearly distributed above the epitaxial layer. The horizontal projection of the current spreading layer on the epitaxial layer does not overlap with the horizontal projection of the bonding portion on the epitaxial layer.
[0015] Optionally, the light-emitting element further includes a bonding layer and a substrate, wherein the bonding layer is formed between the substrate and the epitaxial layer for bonding the epitaxial layer to the substrate, and the substrate is a transparent substrate.
[0016] Optionally, the width of the wire bonding portion of the electrode structure is between 50 μm and 100 μm, the width of the connecting portion is smaller than the width of the wire bonding portion, the width of the through hole in the insulating layer is between 4 μm and 20 μm, and the width of the connecting portion is 2 μm to 10 μm larger than the width of the through hole in the insulating layer.
[0017] Optionally, the projection of the wire bonding portion on the epitaxial layer is circular, the projection of the connection portion of the second electrode on the epitaxial layer is arc-shaped, and the connection portion of the second electrode is located at the edge of the wire bonding portion.
[0018] Optionally, an ohmic contact layer is further formed on the semiconductor layer of the second conductivity type. The ohmic contact layer is located below the current spreading layer and does not overlap with the wire bonding portion of the second electrode.
[0019] Optionally, the ohmic contact layer is located below the current spreading layer, and the ohmic contact layer does not overlap with the connection portion of the second electrode.
[0020] Optionally, an ohmic contact layer is further formed on the semiconductor layer of the second conductivity type, the ohmic contact layer being located below the current spreading layer, and the ohmic contact layer not overlapping the connection portion of the second electrode.
[0021] Optionally, the ohmic contact layer has a strip structure, and the length of the ohmic contact layer is less than the length of the current spreading layer.
[0022] According to another embodiment of the present invention, a light-emitting device is provided, comprising: a die-bonding substrate and a light-emitting element fixed to the die-bonding substrate, wherein the light-emitting element is the light-emitting element provided by the present invention.
[0023] As described above, the light-emitting element and light-emitting device of this application have the following beneficial effects:
[0024] The light-emitting element of this application includes a substrate, an epitaxial layer located on the front side of the substrate, an insulating layer formed on the surface of the epitaxial layer, and an electrode structure. The electrode structure includes a first electrode electrically connected to a semiconductor layer of a first conductivity type and a second electrode electrically connected to a semiconductor layer of a second conductivity type. The electrode structure includes a wire bonding portion and a connecting portion. The wire bonding portion is located above the insulating layer, and the connecting portion extends from the edge of the wire bonding portion through the insulating layer toward the epitaxial layer. The connecting portion of the electrode structure is configured to extend from the edge of the wire bonding portion toward the epitaxial layer, and the projection of the wire bonding portion on the front side of the substrate does not coincide with the projection of the connecting portion on the front side of the substrate. This design ensures that the entire wire bonding portion is located above the insulating layer, resulting in a flat surface and improved reliability during the chip bonding process. Furthermore, the wire bonding portion is located above the insulating layer, which has high hardness, effectively dispersing the impact force during the bonding process, thereby improving chip reliability.
[0025] The insulating layer of this application is preferably an insulating reflective layer, such as a DBR reflective layer. In this case, the wire bonding portion of the metal material and the insulating reflective layer form an ODR structure, which can increase the reflection of light emitted from the epitaxial layer, improve the light extraction efficiency of the light-emitting element, and increase the brightness of the light-emitting element.
[0026] The light-emitting device of this application uses a transparent die-bonding adhesive with a certain refractive index to fix the light-emitting element to the die-bonding substrate, so that more light is emitted from the chip and reflected by the die-bonding substrate with a reflective surface, which greatly improves the external quantum efficiency of the chip and improves the light-emitting efficiency of the light-emitting device. Attached Figure Description
[0027] Figure 1 The diagram shown is a schematic diagram of the structure of the light-emitting element provided in Embodiment 1 of this application.
[0028] Figure 2 Displayed as Figure 1 The diagram shows a top view of the light-emitting element.
[0029] Figure 3 The diagram shown is a schematic diagram of the structure of the light-emitting element provided in Embodiment 2.
[0030] Figure 4 Displayed as Figure 3 The diagram shows a top view of the light-emitting element.
[0031] Figure 5 The diagram shown is a schematic diagram of the light-emitting device provided in Embodiment 2 of this application.
[0032] Component designation explanation
[0033] 100, Substrate; 101, Epitaxial layer; 1011, Semiconductor layer of first conductivity type; 1012, Active region; 1013, Semiconductor layer of second conductivity type; 102, Bonding layer; 1031, First electrode; 1032, Second electrode; 1033, Wire bonding portion; 1034, Connector portion; 104, Insulating layer; 105, Current spreading layer; 106, Ohmic contact layer; 200, Die-bonding substrate; 201, Die-bonding adhesive. Detailed Implementation
[0034] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0035] Example 1
[0036] This embodiment provides a light-emitting element, such as... Figure 1 As shown, the light-emitting element in this embodiment includes a substrate 100, which has a front side and a back side disposed opposite to each other. An epitaxial layer 101 is formed on the front side of the substrate 100. The epitaxial layer 101 includes a first conductivity type semiconductor layer 1011, an active layer 1012, and a second conductivity type semiconductor layer 1013, which are sequentially stacked on the front side of the substrate 100. Optionally, the substrate 100 may be a transparent substrate such as a sapphire substrate, which is suitable for bonding the epitaxial layer 101 and does not affect the light emission of the light-emitting element.
[0037] The aforementioned epitaxial layer 101 can be an AlGaInP series material layer, specifically a quaternary epitaxial layer 101, capable of radiating red light when energized. Preferably, the aforementioned semiconductor layer 1011 of the first conductivity type can be a P-type layer, and the semiconductor layer 1013 of the second conductivity type can be an N-type layer. The aforementioned epitaxial layer 101 is bonded to the substrate 100 via a bonding layer 102. Preferably, the side of the epitaxial layer 101 facing the substrate 100 is formed with a rough surface to reduce the number of reflections during light output and improve the brightness of the light-emitting element.
[0038] For example, a growth substrate is first provided, and a semiconductor layer 1013 of a second conductivity type, an active layer 1012 and a semiconductor layer 1011 of a first conductivity type are sequentially grown on the growth substrate. Then, a bonding layer 102 is formed above the semiconductor layer 1011 of the first conductivity type, and the epitaxial layer 101 is bonded to the substrate 100 through the bonding layer 102. Then, the growth substrate is removed.
[0039] Similarly, Figure 1 As shown, a mesa is formed in the epitaxial layer 101, which exposes a semiconductor layer 1011 of a first conductivity type for subsequent electrode structure formation. An insulating layer 104 is formed on the surface sidewalls of the epitaxial layer 101. Specifically, the insulating layer 104 is formed on the surface of the semiconductor layer 1013 of the second conductivity type, the surface of the semiconductor layer 1011 exposed by the first mesa, and the exposed sidewalls of the epitaxial layer 101. The insulating layer 104 protects the epitaxial layer 101 from damage by external moisture or contaminants, ensuring the optical and electrical properties of the epitaxial layer 101. Preferably, the insulating layer 104 can be a single layer with a refractive index lower than that of the epitaxial layer 101, which can reflect light, such as a SiO2 layer or a SiNx layer; or the insulating layer 104 can be multilayered, such as a combination of two layers of SiO2 and SiNx, or a multilayer structure of alternating SiO2 and TiO2. The insulating layer 104 is formed as a reflective structure layer to reflect the light radiated from the active layer 1012 of the epitaxial layer 101, thereby improving the light extraction efficiency of the light-emitting element.
[0040] The insulating layer 104 has at least two through holes, each with a width of 4μm to 20μm, and the shape of the hole can be circular or elliptical.
[0041] like Figures 1-2 As shown, an electrode structure is formed above the epitaxial layer 101. This electrode structure includes a first electrode 1031 and a second electrode 1032. The first electrode 1031 is formed on a first mesa, that is, above the semiconductor layer 1011 of the first conductivity type, and is electrically connected to the semiconductor layer 1011 of the first conductivity type. The second electrode 1032 is formed above the semiconductor layer 1013 of the second conductivity type and is electrically connected to the semiconductor layer 1013 of the second conductivity type. (See attached diagram.) Figure 2 Both the first electrode 1031 and the second electrode 1032 include a wire bonding portion 1033 and a connecting portion 1034. The wire bonding portion 1033 is formed above the insulating layer 104, preferably at a corner of the light-emitting element. The connecting portion 1034 extends downward from the edge of the wire bonding portion 1033, penetrates a through-hole in the insulating layer 104, and connects to a semiconductor layer 1011 of the first conductivity type or a semiconductor layer 1013 of the second conductivity type. Figure 3As shown, the horizontal projected area of the bonding portion 1033 on the front side of the substrate 100 (i.e., on the epitaxial layer 101) is larger than the horizontal projected area of the connecting portion 1034 on the front side of the substrate 100, and the horizontal projection of the bonding portion 1033 on the front side of the substrate 100 does not coincide with the horizontal projection of the connecting portion 1034 on the front side of the substrate 100. Preferably, the horizontal projection of the bonding portion 1033 on the front side of the substrate 100 is circular. For example, the bonding portion 1033 of the first electrode 1031 is formed into a circular structure on the surface of the epitaxial layer 101, or as shown in the figure. Figure 2 As shown, at least two adjacent right-angled sides of the bonding portion 1033 of the first electrode 1031 are connected to an arc-shaped side; more preferably, two of the adjacent right-angled sides may be parallel to the two edges of the rectangular chip. For example, the horizontal projection of the bonding portion 1033 of the second electrode 1032 on the front side of the substrate 100 is a circular structure.
[0042] The width of the wire bonding portion 1033 of the first electrode 1031 and the second electrode 1032 is between 50μm and 100μm. It can be reasonably designed according to different wire bonding requirements.
[0043] Preferably, the connecting portion 1034 penetrates the through hole of the insulating layer 104. The shape of the connecting portion 1034 can be similar to the shape of the through hole of the insulating layer 104, such as an arc shape. The size of the connecting portion 1034 can be slightly larger than the size of the through hole of the insulating layer 104, at least covering the through hole of the insulating layer 104 and penetrating the through hole of the insulating layer 104. For example, the width of the connecting portion 1034 is 2μm to 10μm larger than the width of the through hole.
[0044] from Figure 1 It can be seen that the through hole of the insulating layer 104 is also located on one side of the wire bonding section.
[0045] Since the connecting portion 1034 extends downward from the edge of the wire bonding portion 1033 and does not overlap with the wire bonding portion 1033, the surface of the wire bonding portion 1033 is smoother, which is beneficial to improving the reliability of the wire bonding portion 1033 during the wire bonding process and ensuring the electrical performance of the light-emitting element. At the same time, the wire bonding portion 1033 is formed above the insulating layer 104. Since the insulating layer 104 has high hardness, it can effectively disperse the impact force during the wire bonding process, thereby improving the reliability of the electrode structure. In addition, as mentioned above, the insulating layer 104 can also be formed as a reflective structure. The metal forming the electrode structure is formed above the insulating layer 104. Therefore, the electrode structure and the insulating layer 104 can form an ODR structure, which increases the reflection of light radiated from the active layer 1012, improves the light extraction rate of the light-emitting element, and is beneficial to improving the brightness of the light-emitting element.
[0046] In an optional embodiment, the projected area of the electrode structure on the front side of the substrate 100 accounts for 1% to 30% of the projected area of the epitaxial layer 101 on the front side of the substrate 100. Compared to the flip-chip structure, the upright electrode structure significantly reduces the area ratio of the electrode structure. Meanwhile, as described above, the electrode structure and the insulating layer 104 form an ODR structure, increasing light reflection.
[0047] In addition, as in the same way Figure 1 and Figure 2 As shown, the light-emitting element in this embodiment further includes a current spreading layer 105, which is formed above a first conductivity type semiconductor layer 1011 and a second conductivity type semiconductor layer 1013. Furthermore, a connection portion 1034 of the electrode structure is formed above the current spreading layer 105 and connected to it. Preferably, as shown... Figure 2 As shown, the current spreading layer 105 is distributed in a linear structure above the epitaxial layer 101. The current spreading layer 105 facilitates the lateral spread of current and improves the electrical performance of the light-emitting element.
[0048] The current spreading layer 105 is connected to the first electrode 1031 and the second electrode 1032, respectively. The number of current spreading layers 105 connected to the first electrode 1031 can be one or more, and the number of current spreading layers 105 connected to the second electrode 1032 can also be one or more. Figure 2 As shown, there are two connection portions 1034. The number of current spreading layers 105 above the epitaxial layer 101 corresponds to the number of connection portions 1034. That is, each connection portion 1034 is in contact with one end of a linear current spreading layer 105.
[0049] In another optional embodiment of this example, please refer to Figure 4 As shown, the electrode structure, taking the second electrode 1032 as an example, includes a bonding portion 1033 and three connecting portions 1034 extending downward from the edge of the bonding portion 1033. The bonding portion 1033 is preferably located at the corner of the light-emitting element, and the three connecting portions 1034 are evenly distributed on the side away from the corner of the light-emitting element. Three current spreading layers 105 are formed above the second conductivity type semiconductor layer 1013, and are respectively connected to the three connecting portions 1034.
[0050] The wire bonding portion 1033 of the first electrode 1031 and the second electrode 1032 is made of the same material, comprising multiple layers of metal, including at least an adhesive layer (not shown) and a wire bonding layer (not shown). The adhesive layer is Ti or Cr, with a thickness of 2.5 nm to 10 nm, or even thicker, such as 10 nm to 20 nm, or even thicker, such as 20 nm to 50 nm. The wire bonding layer is Au, with a thickness of 1 μm to 4 μm. The wire bonding portion 1033 may also include an intermediate layer (not shown), such as a Pt layer, between the adhesive layer and the wire bonding layer, which serves as a barrier. If the adhesive layer is relatively thin, it can reflect light to a certain extent through the intermediate layer or the wire bonding layer, thereby enhancing the reflectivity of the wire bonding electrode and thus increasing the brightness.
[0051] The material of the connection portion 1034 between the first electrode 1031 and the second electrode 1032 can be the same as that of the wire bonding portion 1033. They are formed using the same process steps and are connected to each other, and both include the same multilayer material. The difference between the wire bonding portion 1033 and the connection portion 1034 of the electrode structure lies in their different positions and functions.
[0052] The current spreading layer 105 of the first electrode 1031 and the second electrode 1032 is composed of multiple metal layers, including a metal ohmic contact layer (not shown). When the first electrode 1031 is a P-type electrode, its metal ohmic contact layer may include a layer formed by combining Au and Be elements or Au and Zn elements, and may also include a protective layer (not shown) formed on the metal ohmic contact layer. The protective layer may be Pt to prevent the diffusion of metal elements in the metal ohmic contact layer. When the second electrode 1032 is an N-type electrode, its metal ohmic contact layer may include a layer formed by combining Au, Ge, and Ni elements, and may also include a protective layer, which may be Pt, to prevent the diffusion of metal elements in the metal ohmic contact layer. Of course, the current spreading layer 105 may also not include a protective layer. Preferably, the width of the current spreading layer is 3μm to 8μm.
[0053] Optionally, an ohmic contact layer 106 may be formed below the current spreading layer 105 connected to the second electrode 1032. To achieve a good ohmic contact between the semiconductor layer (second conductivity type semiconductor layer 1013) and the current spreading layer 105, an ohmic contact layer 106 is formed above the second conductivity type semiconductor layer 1013. The ohmic contact layer 106 can be linear in shape and is located below the current spreading layer 105. The length of the ohmic contact layer 106 can be equal to or shorter than the current spreading layer 105, and the width can be equal to or greater than the width of the current spreading layer 105. For example, the width of the ohmic contact layer 106 can be 3 μm to 9 μm. As a preferred embodiment, such as... Figure 2As shown, the ohmic contact layer 106 is not located below the via of the insulating layer 104, and one end of the linear ohmic contact layer 106 is at a certain distance from the via of the insulating layer 104; optionally, the other end of the ohmic contact layer 106 is aligned with one end of the current spreading layer 105. Optionally, for example, when the second electrode 1032 is an N-type electrode, the ohmic contact layer 106 can be gallium arsenide, doped with N-type.
[0054] Example 2
[0055] This embodiment also provides a light-emitting element, but the difference between it and the light-emitting element provided in Embodiment 1 is that:
[0056] like Figure 3 and Figure 4 As shown, the ohmic contact layer 106 is formed into multiple block structures distributed linearly, which is more conducive to the spread of current. At the same time, it can reduce the area of the ohmic contact layer 106 and reduce the light absorption problem caused by gallium arsenide doping to N-type.
[0057] When the ohmic contact layer 106 consists of multiple block structures, the widths of two adjacent block structures may be the same or different, and / or the spacing may be the same or different, which can be adjusted according to actual needs.
[0058] Example 3
[0059] This embodiment provides a light-emitting device, such as... Figure 5 As shown, the light-emitting device includes a die-bonding substrate 200 and a light-emitting element located on the die-bonding substrate 200. The light-emitting element can be the light-emitting element provided in Embodiment 1 and / or Embodiment 2 of this application. The die-bonding substrate 200 can be a ceramic substrate, a printed circuit board, etc. A die-bonding region is provided above the die-bonding substrate 200, and the light-emitting element is fixed to this die-bonding region, for example, by using a die-bonding adhesive 201 with a certain refractive index to fix the light-emitting element to the die-bonding substrate 200. Therefore, the die-bonding adhesive 201 can further reflect the light emitted by the light-emitting element, improving the light extraction efficiency of the light-emitting device.
[0060] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.
Claims
1. A light-emitting element, characterized in that, include: An epitaxial layer, the epitaxial layer comprising at least a semiconductor layer of a first conductivity type, an active layer and a semiconductor layer of a second conductivity type stacked sequentially, the epitaxial layer having a first mesa, the first mesa exposing the semiconductor layer of the first conductivity type; An insulating layer is formed on the epitaxial layer, and the insulating layer has through holes; An electrode structure includes a first electrode electrically connected to a semiconductor layer of the first conductivity type and a second electrode electrically connected to a semiconductor layer of the second conductivity type. The electrode structure includes a wire bonding portion and at least one connecting portion. The wire bonding portion is located above the insulating layer, the connecting portion is located at the edge of the wire bonding portion, and the through hole penetrating the insulating layer extends toward the epitaxial layer. The horizontal projection of the wire bonding portion on the epitaxial layer does not coincide with the horizontal projection of the connecting portion on the epitaxial layer. At least one current spreading layer is formed above the epitaxial layer, and at least one current spreading layer is connected to at least one connection portion in a one-to-one correspondence. The horizontal projection of the current spreading layer on the epitaxial layer does not overlap with the horizontal projection of the bonding portion on the epitaxial layer. An ohmic contact layer is also formed on the semiconductor layer of the second conductivity type. The ohmic contact layer is located below the current spreading layer and does not overlap with the wire bonding portion of the second electrode.
2. The light-emitting element according to claim 1, characterized in that, The horizontal projected area of the bonding portion on the epitaxial layer is greater than the horizontal projected area of the connecting portion on the epitaxial layer.
3. The light-emitting element according to claim 1, characterized in that, The insulating layer is an insulating reflective layer, which can be a single-layer structure or a multi-layer structure formed by repeatedly stacking two layers of material.
4. The light-emitting element according to claim 1, characterized in that, The horizontal projected area of each of the electrode structures on the epitaxial layer accounts for 1% to 30% of the horizontal projected area of the epitaxial layer.
5. The light-emitting element according to claim 1, characterized in that, The current-spreading layer is linearly distributed above the epitaxial layer.
6. The light-emitting element according to claim 1, characterized in that, It also includes a bonding layer and a substrate, wherein the bonding layer is formed between the substrate and the epitaxial layer for bonding the epitaxial layer to the substrate, and the substrate is a transparent substrate.
7. The light-emitting element according to claim 1, characterized in that, The width of the wire bonding portion of the electrode structure is between 50 μm and 100 μm, the width of the connecting portion is smaller than the width of the wire bonding portion, the width of the through hole in the insulating layer is between 4 μm and 20 μm, and the width of the connecting portion is 2 μm to 10 μm larger than the width of the through hole in the insulating layer.
8. The light-emitting element according to claim 1, characterized in that, The projection of the wire bonding portion on the epitaxial layer is circular, and the projection of the connection portion of the second electrode on the epitaxial layer is arc-shaped. The connection portion of the second electrode is located at the edge of the wire bonding portion.
9. The light-emitting element according to claim 1, characterized in that, The ohmic contact layer is located below the current spreading layer, and the ohmic contact layer does not overlap with the connection portion of the second electrode.
10. The light-emitting element according to claim 9, characterized in that, The ohmic contact layer has a strip-shaped structure, and the length of the ohmic contact layer is less than the length of the current spreading layer.
11. A light-emitting device, characterized in that, include: A die-bonded substrate and a light-emitting element fixed to the die-bonded substrate, wherein the light-emitting element is the light-emitting element according to any one of claims 1 to 10.