Light emitting diode and light emitting device

Abstract

The application provides a light emitting diode and a light emitting device. The metal reflecting layer of the light emitting diode is provided with a cladding layer at the periphery. The metal reflecting layer extends to the edge of the light emitting diode to form a trailing structure. The extension of the trailing structure to the edge of the light emitting diode does not exceed the edge of the cladding layer. The arrangement makes the metal reflecting layer completely wrapped. When the metal reflecting layer contains Ag, the Ag can be prevented from being precipitated, and thus the reliability problems such as electric leakage can be prevented. The metal reflecting layer is completely wrapped, the structure is not damaged, the reflecting effect is guaranteed, and thus the light emitting effect of the light emitting diode can be improved. In addition, the metal reflecting layer forms the trailing structure, so that the cladding layer above the metal reflecting layer has a good covering effect, and the adhesion effect between adjacent layer structures is improved. The trailing structure is beneficial to the filling of metal during bonding, improves the bonding effect, and further improves the reliability and stability of the light emitting diode.

Description

Technical Field

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

[0002] The basic structure of a light-emitting diode (LED) consists of a PN junction between P-type and N-type semiconductors. When a forward voltage is applied to the LED, electrons and holes recombine at the junction, releasing energy as photons, which then form light radiation. With the rapid development of LEDs, the requirements for them have become increasingly stringent. For example, higher optical parameters (such as luminous flux, luminous efficiency, and luminous intensity) are desirable, as are smaller fluctuations in stability (such as color temperature, color coordinates, light decay, and reliability).

[0003] For reverse-polarity light-emitting diodes (LEDs), they typically have a vertical structure, consisting of a substrate, a silver mirror, a dielectric layer, and an epitaxial layer stacked sequentially. Through-holes are provided in the dielectric layer, and conductive material is placed within these holes to electrically connect to the epitaxial layer. Since the silver mirror usually covers the entire surface of the dielectric layer, this arrangement exposes the Ag metal on the sidewalls of the silver mirror to the air after the LED is diced. During prolonged operation, the Ag metal is prone to oxidation and migration to the epitaxial layer at the dicing location, leading to leakage current in the reverse-polarity LED and consequently degrading its optical parameters and stability. Summary of the Invention

[0004] In view of the defects and shortcomings of the existing light-emitting diodes in terms of light emission, the purpose of this application is to provide a light-emitting diode and a light-emitting device to obtain a light-emitting diode product with better light emission effect and more stable performance.

[0005] To achieve the above and other related objectives, in a first aspect, this application provides a light-emitting diode, which includes at least a substrate, a bonding layer, a cladding layer, a metal reflective layer, and a semiconductor epitaxial stack stacked sequentially.

[0006] The coating layer is located between the metal reflective layer and the bonding layer. The metal reflective layer includes a main body portion and a trailing structure extending from the main body portion toward the edge of the light-emitting diode. The end of the trailing structure extending toward the edge of the light-emitting diode does not exceed the edge of the coating layer.

[0007] This application also provides a light-emitting device, including a circuit board and a light-emitting element disposed on the circuit board, wherein the light-emitting element includes the light-emitting diode provided in this application.

[0008] Compared with the prior art, the light-emitting diode and light-emitting device provided in this application have at least the following beneficial effects:

[0009] In the technical solution of this application, a cladding layer is provided around the metal reflective layer of the light-emitting diode (LED). The metal reflective layer extends towards the edge of the LED to form a trailing structure, and the cladding layer covers the trailing structure. The end of the trailing structure extending towards the edge of the LED does not exceed the edge of the cladding layer. This arrangement ensures that the metal reflective layer is completely encapsulated. When the metal reflective layer contains Ag, Ag deposition is prevented, thus preventing reliability issues such as leakage. The complete encapsulation of the metal reflective layer preserves its structure, ensuring reflection and improving the light emission performance of the LED. Furthermore, the trailing structure provides good coverage for the cladding layer above the metal reflective layer, improving adhesion between adjacent layers. This trailing structure also facilitates metal filling during bonding, improving bonding and further enhancing the reliability and stability of the LED.

[0010] In addition, the light-emitting devices provided in this application all include the light-emitting diodes provided by the above-mentioned technical solutions. Therefore, the light-emitting devices also have the above-mentioned good technical effects. Attached Figure Description

[0011] Figure 1 The diagram shown is a structural schematic of a light-emitting diode in the prior art.

[0012] Figure 2 The diagram shown is a schematic diagram of the structure of a light-emitting diode provided in Embodiment 1 of this application.

[0013] Figure 3 The diagram shown is a schematic representation of the structure of a light-emitting diode in one of the optional examples.

[0014] Figure 4 Displayed as Figure 2 The diagram shown is a top-down view of the structure of a light-emitting diode. For ease of illustration, only the projected outline of a portion of the structure is shown.

[0015] Figure 5 Displayed as Figure 2 The diagram shown is a top-down view of the structure of a light-emitting diode. For ease of illustration, the first electrode and the projected outline of the via in the dielectric layer are highlighted.

[0016] Figure 6 The diagram shown is a flowchart illustrating the manufacturing method of a light-emitting diode as described in Example 1.

[0017] Figure 7 The diagram shows an epitaxial structure formed on a growth substrate.

[0018] Figure 8 Displayed as in Figure 7 The diagram shows a transparent conductive layer and a dielectric layer formed on top of the structure, with a through-hole formed in the dielectric layer and a conductive material formed in the through-hole.

[0019] Figure 9 Displayed as in Figure 8 The diagram shows a patterned photoresist layer formed on top of the dielectric layer.

[0020] Figure 10 Displayed as in Figure 9 A schematic diagram of the metallic material deposited on top of the structure shown.

[0021] Figure 11 Shown as peeled off Figure 10 The diagram shows the photoresist portion and the layer formed on top of the metal reflective layer.

[0022] Figure 12 Displayed as Figure 11 Electron micrographs of the metallic reflective layer and the coating layer are shown.

[0023] Figure 13 The schematic diagram of the structure of the light-emitting diode provided in Embodiment 2 of this application.

[0024] Figure 14 The diagram shown is a schematic diagram of the light-emitting device provided in Embodiment 3 of this application.

[0025] List of reference numerals in the attached diagram:

[0026] 11. Substrate; 12. Epitaxial layer; 13. Silver mirror; 14. Dielectric layer.

[0027] 110. Semiconductor epitaxial stack; 101. Mesa structure; 111. N-type semiconductor layer; 112. Active layer; 113. P-type semiconductor layer; 114. Ohmic contact layer; 115. Current spreading layer; 120. Dielectric layer; 121. Through-hole; 130. Metal reflective layer; 131. Main body; 132. Trailing structure; 140. Substrate; 151. First electrode; 1511. Main body; 1512. Extension; 152. Second electrode; 153. Transparent conductive layer; 160. Conductive pillar; 170. Insulating protective layer; 180. Covering layer; 181. First part; 182. Second part; 190. Bonding layer.

[0028] 200, Growth substrate; 210, Patterned photoresist layer; 211, Opening; 212, Gap.

[0029] 300, Light-emitting device; 310, Substrate; 311, Device layer; 312, Interconnect layer; 320, Light-emitting unit. Detailed Implementation

[0030] The following specific embodiments illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application 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 this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0031] It should be noted that the illustrations provided in the embodiments of this application are merely schematic representations of the basic concept of this application. Although the illustrations only show components relevant to this application and are not drawn according to the actual number, shape, and size of components in implementation, the shape, quantity, and proportion of each component can be arbitrarily changed in actual implementation, and the layout of the components may also be more complex. The structures, proportions, sizes, etc., shown in the accompanying drawings are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the implementation conditions of this application. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and purposes that this application can produce, should still fall within the scope of the technical content disclosed in this application.

[0032] See Figure 1 In the prior art, a light-emitting diode includes a substrate 11, a silver mirror 13, a dielectric layer 14, and an epitaxial layer 12 stacked sequentially. For example... Figure 1 As shown, the silver mirror 13 covers the entire surface of the dielectric layer 14. Figure 1 In the individual chip shown, the metal Ag on the sidewall of the silver mirror 13 is exposed to the air. When the light-emitting diode is lit for a long time, the metal Ag is easily oxidized and easily migrates from the silver mirror 13 along the sidewall of the light-emitting diode to the epitaxial layer 12, which leads to reliability problems such as leakage and short circuit. This in turn leads to a decrease in the light parameters and stability of the light-emitting diode, all of which will affect the light output efficiency of the light-emitting diode.

[0033] To address the aforementioned technical deficiencies, this application provides a light-emitting diode, which includes at least a substrate, a bonding layer, a cladding layer, a metal reflective layer, and a semiconductor epitaxial stack stacked sequentially.

[0034] The coating layer is located between the metal reflective layer and the bonding layer. The metal reflective layer includes a main body portion and a trailing structure extending from the main body portion toward the edge of the light-emitting diode. The end of the trailing structure extending toward the edge of the light-emitting diode does not exceed the edge of the coating layer.

[0035] By adopting the above technical solution, the tail structure extends to the edge of the light-emitting diode (LED) without exceeding the edge of the cladding layer, ensuring that the metal reflective layer is completely encapsulated. When the metal reflective layer contains Ag, Ag deposition is prevented, thus preventing reliability issues such as leakage. The complete encapsulation of the metal reflective layer preserves its structure and ensures reflection, thereby improving the light emission performance of the LED. Furthermore, the tail structure provides good coverage for the cladding layer above it, improving adhesion between adjacent layers. This tail structure also facilitates metal filling during bonding, enhancing bonding and further improving the reliability and stability of the LED.

[0036] Optionally, the line connecting the end and the starting point of the trailing structure has an angle α with the plane containing the surface of the metal reflective layer away from the metal bonding layer, where 5°≤α<90°, and the starting point is the junction of the trailing structure, the main body, and the covering layer.

[0037] Optionally, 5°≤α≤30°.

[0038] Optionally, the extension distance D0 of the trailing structure toward the edge of the light-emitting diode does not exceed the width W of the second portion of the covering layer that covers the trailing structure.

[0039] The aforementioned limitation of the included angle α and the limitation of the extension distance of the trailing structure indicate that the metal reflective layer forms a trailing structure toward the edge of the light-emitting diode, and the trailing structure forms a structure with a small slope, which is beneficial to improving the coverage effect of the metal reflective layer on the dielectric layer, and at the same time, it is beneficial to the adhesion of the subsequently formed material layer on the metal reflective layer, thereby improving the reliability of the light-emitting diode.

[0040] Optionally, the semiconductor epitaxial stack is formed as a mesa structure, and the edge of the main body portion of the metal reflective layer and the edge of the mesa structure have a first spacing distance D1, 1μm≤D1≤25μm.

[0041] The first spacing mentioned above causes the metal reflective layer to be recessed relative to the edge of the LED, preventing it from extending to the edge of the LED. This avoids migration of substances like Ag within the metal reflective layer, thus improving the LED's optical parameters and reliability. Simultaneously, it ensures that the metal reflective layer covers the LED's light-emitting area, enhancing reflection and increasing the LED's light extraction efficiency.

[0042] Optionally, the extension distance D0 of the trailing structure toward the edge of the light-emitting diode does not exceed the first interval distance D1.

[0043] The extension distance D0 of the trailing structure does not exceed the first interval distance D1, which further ensures that the metal reflective layer will not extend to the edge of the light-emitting diode, thereby helping to further improve the reliability of the light-emitting diode.

[0044] Optionally, the semiconductor epitaxial stack is formed into a mesa structure, and the ratio of the projected area S1 of the metal reflective layer to the projected area S2 of the mesa structure satisfies: 70% ≤ S1 / S2 < 100%.

[0045] The limitation on the projected area of ​​the aforementioned metal reflective layer and platform structure ensures that the metal reflective layer will not extend to the edge of the light-emitting diode, while also ensuring that the metal reflective layer can cover the light-emitting area of ​​the light-emitting diode, thereby improving the reflection effect and the light extraction efficiency of the light-emitting diode.

[0046] Optionally, the thickness of the main portion of the metal reflective layer is between 200 Å and 6000 Å.

[0047] Optionally, the thickness of the trailing structure gradually increases from the edge of the light-emitting diode toward the center, and the thickness of the trailing structure is not greater than the thickness of the main body portion.

[0048] The thickness of the metal reflective layer ensures a sufficiently high reflection efficiency, while preventing excessive absorption heat and surface roughening, which helps to ensure the performance stability of the light-emitting diode.

[0049] Optionally, the covering layer includes a first portion covering the main body portion and a second portion covering the trailing structure, wherein the first portion and the second portion have the same metal layer structure.

[0050] Optionally, the second part has the same thickness as the first part, and on the side away from the metal reflective layer, there is a height difference between the upper surface of the second part and the upper surface of the first part.

[0051] The first and second parts of the cladding layer can be formed simultaneously. At this time, due to the certain distance between the metal reflective layer and the edge of the light-emitting diode, there is a certain height difference between the cladding structure and the bonding layer. Simultaneously, the presence of the trailing structure creates a smooth transition between the first and second parts, which facilitates the filling of the bonding metal during subsequent bonding, forming a complete structure.

[0052] Optionally, on the side away from the metal reflective layer, the upper surface of the first portion is flush with the upper surface of the second portion.

[0053] The first and second portions of the coating can be formed in steps. For example, the second portion can be formed first to make it flush with the surface of the metal reflective layer, and then the first portion can be formed. This allows the first and second portions to have flush surfaces, which facilitates subsequent bonding.

[0054] Optionally, the coating layer comprises a multilayer structure formed from any of Ni, Tiw, Ti, Pt, and Au.

[0055] The choice of materials for the coating structure can effectively block the diffusion and migration of active ions such as Ag, thereby improving the reliability of the light-emitting diode.

[0056] Optionally, the light-emitting diode further includes a dielectric layer located between the semiconductor epitaxial stack and the metal reflective layer; the dielectric layer has a via, and the via is filled with the metal reflective layer.

[0057] Optionally, a transparent conductive layer is further provided between the metal reflective layer and the semiconductor epitaxial stack within the via.

[0058] The metal reflective layer and transparent conductive layer inside the through-hole enable electrical connection between the epitaxial layer and the electrode structure. The transparent conductive layer can also improve the current diffusion effect, which is beneficial to improving the light parameter of the light-emitting diode.

[0059] This application also provides a light-emitting device, which includes a circuit board and a light-emitting element disposed on the circuit board, wherein the light-emitting element includes the light-emitting diode provided in this application.

[0060] The light-emitting device includes the light-emitting device described above in this application, and therefore also has better light emission effect and good control performance.

[0061] The following examples will now be used to provide a detailed description. For ease of understanding, the growth direction of the semiconductor epitaxial stack is defined as growing from bottom to top, with the substrate located below the semiconductor epitaxial stack and the electrode structure located above the semiconductor epitaxial stack.

[0062] Example 1

[0063] This embodiment provides a light-emitting diode (LED), see [link]. Figure 2 The light-emitting diode includes a substrate 140, a semiconductor epitaxial stack 110, a bonding layer 190 between the substrate 140 and the semiconductor epitaxial stack 110, a metal reflective layer 130 between the bonding layer 190 and the semiconductor epitaxial stack 110, and a cladding layer 180 between the metal reflective layer 130 and the bonding layer 190. The semiconductor epitaxial stack 110 can be any material capable of emitting light under voltage, such as GaN, GaAs, AlGaN, AlInP, AlGaInP, or AlGaP. Similarly... Figure 2 As shown, the semiconductor epitaxial stack 110 includes an N-type semiconductor layer 111, an active layer 112, and a P-type semiconductor layer 113.

[0064] The N-type semiconductor layer 111, active layer 112, and P-type semiconductor layer 113 may include semiconductor material layers of group III-V elements, such as Al, Ga, In, and P. The N-type semiconductor layer 111 may include N-type impurities such as Si, Ge, and Sn, while the P-type semiconductor layer 113 may include P-type impurities such as Mg, Sr, Ba, and Zn. The active layer 112 provides the region for electron-hole recombination and emits light. Different materials can be selected depending on the emission wavelength. The active layer 112 is made of aluminum gallium indium phosphide (AlGaInP) series materials, emitting red, yellow, or orange light. The active layer 112 can be a single heterostructure (SH), a double heterostructure (DH), a double-sided double heterostructure (DDH), or a multi-quantum well (MQW). The active layer 112 comprises a well layer and a barrier layer, wherein the barrier layer has a larger band gap than the well layer. By adjusting the composition ratio of the semiconductor material in the active layer 112, it is desired to radiate light of different wavelengths. In this embodiment, the active layer 112 radiates light in the 550nm–900nm wavelength range, such as red, yellow, and orange light, and further, radiates red light. The active layer 112 is a material layer that provides electroluminescent radiation, such as aluminum gallium indium phosphide (AGaInP) or aluminum gallium arsenide (AGaAs), more preferably AGaInP, which can be a single quantum well or a multi-quantum well.

[0065] In this embodiment, the active layer 112 may optionally be a multi-quantum-well layer, comprising alternating AlGaInP quantum well layers and AlGaInP quantum barrier layers, wherein the Al content in the AlGaInP quantum well layers and AlGaInP quantum barrier layers is different. The multi-quantum-well layer may comprise alternating stacked AlGaInP quantum well layers and AlGaInP quantum barrier layers for 1 to 200 cycles. As an example, the multi-quantum-well layer comprises alternating stacked AlGaInP quantum well layers and AlGaInP quantum barrier layers for 5 cycles.

[0066] Similarly, refer to Figure 2The light-emitting diode may further include an ohmic contact layer 114 formed on the side of the N-type semiconductor layer 111 away from the active layer 112. This ohmic contact layer 114 may be a heavily doped AlGaAs layer, GaAs layer, AlInP layer, GaInP layer, or AlGaInP layer, etc. The dopant may be an N-type impurity such as Si, Ge, or Sn with a doping concentration greater than or equal to 1.0E+19 atom / cm³. 3 Furthermore, greater than or equal to 1.0E+20atom / cm 3 Optionally, the thickness of the ohmic contact layer 114 is between 10 nm and 500 nm, and more specifically, between 50 nm and 500 nm, 100 nm and 500 nm, 50 nm and 400 nm, 100 nm and 200 nm, etc.

[0067] The semiconductor epitaxial stack 110 is bonded to the substrate 140 from one side of the P-type semiconductor layer 113 via a bonding layer 190. The substrate 140 can be an insulating substrate, a semiconductor substrate, a metal substrate, etc. In this embodiment, the substrate 140 is a silicon (Si) substrate, a germanium (Ge) substrate, a silicon carbide (SiC) substrate, a gallium nitride (GaN) substrate, an aluminum nitride (AlN) substrate, a gallium phosphide (GaP) substrate, or a gallium arsenide (GaAs) substrate, etc. Optionally, the bonding layer 190 is a metal bonding layer, such as Cu, Al, Sn, Au, Ag, Pb, Ti, Ni, In, Pt, or W, etc.

[0068] A dielectric layer 120 is also formed between the metal reflective layer 130 and the semiconductor epitaxial stack 110. Specifically, the dielectric layer 120 is formed on the side of the P-type semiconductor layer 113 away from the active layer 112, the metal reflective layer 130 is formed on the side of the dielectric layer 120 away from the P-type semiconductor layer 113, and the cladding layer 180 covers the metal reflective layer 130.

[0069] like Figure 2 As shown, the metal reflective layer 130 includes a main body portion 131 located in the middle region of the light-emitting diode (LED), and a trailing structure 132 extending from the main body portion 131 toward the edge of the LED. The metal reflective layer 130 is a metal material layer with high reflectivity, such as an Ag layer or an Al layer, preferably an Ag layer with high density and etching resistance, and may also include metal layers such as Ni, Ti, and W. The thickness of the main body portion 131 of the metal reflective layer 130 is between 200 Å and 6000 Å, and more specifically, between 500 Å and 5000 Å, or 1000 Å and 3000 Å. This provides sufficiently high reflection efficiency while preventing absorption heat and surface roughening caused by excessive thickness, thus contributing to the stability of the LED's performance.

[0070] Optional examples, such as Figure 2As shown, the junction of the main body 131 of the metal reflective layer 130 and the trailing structure 132 is defined as the starting point of the trailing structure 132. The line connecting the end of the trailing structure 132 and the starting point forms an angle α with the plane containing the surface of the metal reflective layer 130 away from the metal bonding layer 190, where 5° ≤ α < 90°, and further, 5° ≤ α ≤ 30°. The trailing structure 132 forms a gentle slope structure with a small gradient; further, it forms a similar arc-shaped gentle slope that is concave relative to the line connecting the end of the trailing structure 132 and the starting point (i.e., concave towards the direction of the semiconductor epitaxial stack 110). In optional examples, such as... Figure 3 As shown, the trailing structure 132 can also form an inclined sidewall along the line connecting the end and the starting point. That is, the trailing structure 132 and the main body 131 together form a nearly inverted trapezoidal structure. The above-described structure of the trailing structure 132 is beneficial to improving the coverage effect of the metal reflective layer 130 on the dielectric layer 120, and also facilitates the adhesion of the subsequently formed material layer on the metal reflective layer 130, thereby improving the reliability of the light-emitting diode.

[0071] Similarly, refer to Figure 2 The semiconductor epitaxial stack 110 is formed into a mesa structure 101, the edge of which is recessed relative to the edge of the light-emitting diode (LED). A first spacing distance D1 exists between the edge of the main body portion 131 of the metal reflective layer 130 and the edge of the mesa structure 101. The edge of the main body portion 131 refers to the boundary line between the main body portion 131 and the trailing structure 132. Specifically, 1 μm ≤ D1 ≤ 25 μm, further, 2 μm ≤ D1 ≤ 20 μm, 2 μm ≤ D1 ≤ 15 μm, and 5 μm ≤ D1 ≤ 10 μm. The first spacing distance D1 causes the main body portion 131 of the metal reflective layer 130 to be recessed relative to the edge of the LED, preventing it from extending to the edge of the LED and thus preventing the migration of substances such as Ag in the metal reflective layer. This improves the optical parameters and reliability of the LED. Simultaneously, it ensures that the metal reflective layer 130 covers the light-emitting area (i.e., the central region) of the LED, improving the reflection effect and increasing the light extraction efficiency of the LED. Furthermore, the extension distance D0 of the trailing structure 132 towards the edge of the light-emitting diode does not exceed the first spacing distance D1. This further ensures that the metal reflective layer 130 does not extend to the edge of the light-emitting diode, thereby further improving the reliability of the light-emitting diode.

[0072] Optional examples, such as Figure 4As shown, the projection outline E1 of the light-emitting diode (LED), the projection outline E2 of the mesa structure 101, the projection outline E31 of the main body 131 of the metal reflective layer 130, and the projection outline E32 of the trailing structure 132 are illustrated. The area enclosed by projection outline E31 is the projected area S1 of the metal reflective layer 130, and the area enclosed by projection outline E2 is the projected area S2 of the mesa structure 101. S1 and S2 satisfy the following conditions: 70% ≤ S1 / S2 < 100%, further satisfying 75% ≤ S1 / S2 ≤ 99.5%, and even further satisfying 85% ≤ S1 / S2 ≤ 99%. The limitation on the ratio of the projected areas of the metal reflective layer 130 and the mesa structure 101 ensures that the metal reflective layer 130 does not extend to the edge of the LED, while simultaneously ensuring that the metal reflective layer 130 can cover the light-emitting area of ​​the LED, improving the reflection effect and increasing the light extraction efficiency of the LED.

[0073] Refer again Figure 2 A cladding layer 180 is formed on the surface of the metal reflective layer 130 away from the semiconductor epitaxial stack 110. The cladding layer 180 includes a first portion 181 covering the main body portion 131 of the metal reflective layer 130, and a second portion 182 surrounding the first portion 181 and covering the trailing structure 132. The first portion 181 and the second portion 182 are structurally continuous. The cladding layer 180 covers the metal reflective layer 130, and the second portion 182 covers and surrounds the trailing structure 132. The cladding layer 180 comprises a multilayer structure formed from any combination of Ni, Tiw, Ti, Pt, and Au. Preferably, the cladding layer 180 is a Pt / Ti / Pt / Ti / Pt / Au composite layer. The aforementioned metal material layer can effectively block the migration of Ag in the metal reflective layer. At the same time, since the second part 182 of the coating layer 180 wraps around the periphery of the metal reflective layer 130, it can effectively prevent the migration of Ag along the sidewall of the light-emitting diode, which is beneficial to improving the reliability of the light-emitting diode. On the other hand, it can also effectively block the diffusion of metal elements in the subsequently formed bonding layer 190 into the metal reflective layer 130, ensuring the functional stability of the metal reflective layer 130.

[0074] like Figure 2 and Figure 4As shown, the cladding layer 180 covers the metal reflective layer 130 and extends to the edge of the light-emitting diode, covering the surface of the exposed dielectric layer 120. At this time, the second portion 182 of the cladding layer 180 has a width W in the direction towards the edge of the light-emitting diode, and the extension distance D0 of the trailing structure 132 towards the edge of the light-emitting diode does not exceed the width W of the second portion 182. The extension distance D0 of the trailing structure 132 towards the edge of the light-emitting diode does not exceed the width W of the second portion 182, so that the metal reflective layer 130 is completely encapsulated. When the metal reflective layer 130 contains Ag, Ag deposition can be prevented, thereby preventing reliability problems such as leakage current.

[0075] like Figure 2 As shown, in this embodiment, the first portion 181 and the second portion 182 of the covering layer 180 are continuous structures, and there is no clear boundary between them. That is, the first portion 181 and the second portion 182 are formed simultaneously. The metal layer deposited on the surface of the main body portion 131 of the metal reflective layer 130 forms the first portion 181, and the metal layer deposited on the surface of the trailing structure 132 and the surface of the dielectric layer 120 surrounding the trailing structure 132 forms the second portion 182. (See also...) Figure 11 At this point, there will be a certain height difference Δh between the first part 181 and the second part 182. Since the trailing structure 132 is formed as a gentle slope structure, when forming the first part 181 and the second part 182, the metal material can cover the main part 131 and the trailing structure 132 more evenly and form a slow transition, with good continuity and bonding stability between the two.

[0076] In an optional example, the first portion 181 and the second portion 182 can also be formed stepwise. For example, firstly, a metal layer can be deposited on the surface of the trailing structure 132 of the metal reflective layer 130 and on the surface of the dielectric layer 120 surrounding the trailing structure 132 to form the second portion 182. Then, a metal layer can be deposited on the surface of the main body portion 131 of the metal reflective layer 130 to form the first portion 181. By forming the first portion 181 and the second portion 182 stepwise, the thickness of the deposited metal layer can be controlled so that the upper surfaces of the first portion 181 and the second portion 182 are at the same height, that is, the surfaces away from the metal reflective layer 130 are at the same height. This is beneficial for the subsequent bonding layer 190 to form a flat structure, which facilitates subsequent bonding.

[0077] Similarly, Figure 2 As shown, a bonding layer 190 is provided between the cladding layer 180 and the substrate 140. The bonding layer 190 can be an Au / In composite material layer. Metal In has good fluidity during the bonding process and can fill the height difference Δh portion between the first part 181 and the second part 182 of the cladding layer 180 well, forming a good bond.

[0078] Optional examples, such as Figure 2 As shown, a via 121 is formed in the dielectric layer 120, and a conductive pillar 160 is formed by filling the via 121 with a conductive material, which is electrically connected to the P-type semiconductor layer 113. Further, to increase the adhesion between the conductive pillar 160 and the P-type semiconductor layer 113 and the current spread on the P-type semiconductor layer 113 side, a transparent conductive layer 153 is provided between the dielectric layer 120 and the P-type semiconductor layer 113. This transparent conductive layer 153 can be a material layer such as ITO. In this embodiment, the conductive pillar 160 is a metal reflective layer 130 filled into the via 121 (specifically, the main body portion 131 of the metal reflective layer 130). To increase the adhesion between the metal reflective layer 130 forming the conductive pillar 160 and the transparent conductive layer 153, an adhesion layer, such as IZO, is provided between the conductive pillar 160 and the transparent conductive layer 153. In other alternative examples, the conductive pillar 160 can be formed of a transparent conductive material such as ITO, or a metallic material with good conductivity and stability such as Au or Zn.

[0079] The dielectric layer 120 can be a single-layer structure formed from one of SiO2, SiN, SiON, TiO2, etc., or a multi-layer structure formed from any combination of these materials. Optionally, it can be a DBR structure with reflective properties, such as a DBR structure formed from SiO2 and TiO2. In this embodiment, the dielectric layer 120 is a DBR structure, which forms a total internal reflection structure with the aforementioned metal reflective layer 130, increasing the reflection of light radiated from the active layer 112 and enhancing the light extraction efficiency of the light-emitting diode.

[0080] Similarly, refer to Figure 2 The light-emitting diode in this embodiment further includes an electrode structure, which includes a first electrode 151 and a second electrode 152. The first electrode 151 is formed on the side of the N-type semiconductor layer 111 away from the active layer 112 and is electrically connected to the N-type semiconductor layer 111. On the other side of the substrate 140 opposite to the semiconductor epitaxial stack 110, a back gold layer is formed, which can serve as the second electrode 152 electrically connected to the P-type semiconductor layer 113. The first electrode 151 and the second electrode 152 can be any one or more layer structures selected from Au, Ni, AuGeNi, Ti, Pt, BeAu, and AuZn, and they can have the same or different material composition layers.

[0081] like Figure 5As shown, the projected outline of the first electrode 151 and the projected outline of the via 121 in the dielectric layer 120 are illustrated. The first electrode 151 includes a body portion 1511 and an extension portion 1512 connected to the body portion 1511. The provision of the extension portion 1512 of the first electrode 151 can improve the current diffusion effect and uniformity on the N-type semiconductor layer 111 side. In an optional embodiment, the extension portion 1512 is formed into a finger-like structure, and the first electrode 151 may include one or more of the extension portions 1512. Figure 5 As shown, the distance between the center line of the extension portion 1512 closest to the edge of the light-emitting diode and the projected outline E2 of the mesa structure 101 is D2, and the distance between the geometric center of the through hole 121 closest to the edge of the light-emitting diode and the projected outline E2 of the mesa structure 101 is D3. D3 > D2, and 3μm ≤ D2 ≤ 75μm. Further, 10μm ≤ D2 ≤ 50μm, 10μm ≤ D2 ≤ 20μm, etc.; 10μm ≤ D3 ≤ 50μm, further, 10μm ≤ D2 ≤ 40μm, 15μm ≤ D2 ≤ 30μm, 10μm ≤ D2 ≤ 20μm, etc.

[0082] In this embodiment, the light-emitting diode has a vertical structure, with one side of the N-type semiconductor layer 111 being the light-emitting side. Furthermore, the area not covered by the first electrode 151 is the specific light-emitting area. For example... Figure 2 As shown, in this embodiment, an ohmic contact layer 114 is further included below the first electrode 151 to form a good ohmic contact with the first electrode 151, ensuring the normal operating voltage of the light-emitting diode. Optionally, to prevent current concentration near the electrode, the vias 121 in the dielectric layer 120 are not aligned vertically with the first electrode 151, and are staggered, thereby increasing current diffusion and improving the light-emitting effect. Furthermore, adjacent vias 121 can be arranged as follows: Figure 5 The arrangement shown can be either staggered or aligned.

[0083] In the optional examples, refer to Figure 2 In order to further increase the light extraction efficiency of the light-emitting diode, in this embodiment, after the first electrode 151 is formed, the light-emitting surface outside the area of ​​the first electrode 151 is roughened to form a roughened surface, thereby increasing the light extraction rate.

[0084] Refer again Figure 2 The light-emitting diode in this embodiment also includes an insulating protective layer 170. This insulating protective layer 170 covers the sidewalls of the light-emitting diode, and further covers the edge portions of the sidewalls and surface of the light-emitting surface and the first electrode 151. The insulating protective layer 170 may, for example, be SiO2. x SiN x SiO x Ny Al2O3, TiO x Any one or more combinations thereof. The insulating protective layer 170 can effectively prevent the light-emitting diode, especially the semiconductor epitaxial stack 110, from contamination or damage by external moisture, impurities, etc., ensuring the performance reliability and durability of the light-emitting diode. In addition, the insulating protective layer 170 can also achieve insulation between the first electrode 151 and the second electrode 152, preventing defects such as short circuits between them, and improving the reliability of the light-emitting diode.

[0085] This embodiment also provides a method for manufacturing the aforementioned light-emitting diode. For example... Figure 6 As shown, the manufacturing method includes the following steps:

[0086] Step S101: Provide a growth substrate and form a semiconductor epitaxial stack on the growth substrate, wherein the semiconductor epitaxial stack includes an N-type semiconductor layer, an active layer and a P-type semiconductor layer sequentially stacked from the surface of the growth substrate;

[0087] Step S102: Form a dielectric layer on one side of the P-type semiconductor layer of the semiconductor stack;

[0088] Step S103: A patterned photoresist layer is formed above the dielectric layer, and vias are formed in the dielectric layer;

[0089] Step S104: Deposit a metal material layer above the dielectric layer and photoresist layer and inside the via, and peel off the photoresist layer to form a metal reflective layer;

[0090] Step S105: Form a coating layer over the metal reflective layer;

[0091] Step S106: Form a bonding layer above the cladding layer and bond the semiconductor epitaxial stack to the substrate.

[0092] like Figure 7 As shown, for example, a growth substrate 200 is first provided, and an N-type semiconductor layer 111, an active layer 112, and a P-type semiconductor layer 113 are sequentially grown on the growth substrate 200. Then, as... Figure 8 As shown, a dielectric layer 120 is formed above the P-type semiconductor layer 113. Optionally, a transparent conductive layer 153 is first formed above the P-type semiconductor layer 113 before forming the dielectric layer 120.

[0093] After that, as Figure 9As shown, a patterned photoresist layer 210 is formed above the dielectric layer 120, and the dielectric layer 120 is etched to form a via 121 therein. This via 121 penetrates the dielectric layer 120 to expose the underlying transparent conductive layer 153. The patterned photoresist layer 210 covers the area between adjacent light-emitting diodes (i.e., the dicing area for subsequent dicing of the light-emitting diodes) and exposes the aforementioned via 121, forming an opening 211 in the middle region of the light-emitting diode. Figure 9 As shown, at one end facing the middle region of the light-emitting diode, the sidewall connecting the patterned photoresist layer 210 and the dielectric layer 120 is formed as a gently sloping structure, that is, a gap 212 is formed between the patterned photoresist layer 210 and the dielectric layer 120. Figure 10 As shown, in Figure 9 A metallic material is deposited on the surface of the structure shown. For example, in this embodiment, a metallic material such as Ag or Al, which can form a material layer with good reflective properties, is deposited. Preferably, Ag is deposited. Specifically, metallic material is deposited above the patterned photoresist layer 210, above the dielectric layer 120 exposed by the opening 211, and within the via 121. The metallic material covers the surface of the dielectric layer 120 exposed by the opening 211 and extends into the aforementioned gap 212, covering the dielectric layer 120 and the patterned photoresist layer 210 at the gap 212, and creating a significant discontinuity between the dielectric layer 120 and the patterned photoresist layer 210, facilitating subsequent stripping. The metallic material filling the via 121 forms conductive pillars 160 in the via 121 to achieve electrical connection with the P-type semiconductor layer 113.

[0094] In other alternative examples, the via 121 can first be filled with a transparent conductive material such as ITO, or a metal material with good conductivity and stability such as Au or Zn to form a conductive pillar 160, so as to achieve electrical connection with the P-type semiconductor layer 113. Then, the metal material deposition step is performed.

[0095] Subsequently, the patterned photoresist layer 210 and the metal material layer deposited on it are stripped off, and the remaining metal layer forms a metal reflective layer 130. The metal reflective layer 130 specifically includes a main body portion 131 covering the dielectric layer 120 in the middle of the light-emitting diode and a trailing structure 132 extending from the main body portion 131. The specific structure can be referred to the above description of the light-emitting diode, and will not be repeated here.

[0096] Then as Figure 11 As shown, a metal layer is deposited above the metal reflective layer 130 to form a cladding layer 180. (As illustrated...) Figure 11 As shown, in Figure 10A metallic material, such as a Pt-Ti-Pt-Ti-Pt-Au metal layer, is deposited sequentially on the front side of the structure shown to form a cladding layer 180. At this time, the cladding layer 180 has the same morphology as the metal reflective layer 130, namely, a first portion 181 covering the main body portion 131 of the metal reflective layer 130, and a second portion 182 extending from the first portion 181 and covering the trailing structure 132, also forming a gently sloping structure. There is a height difference Δh between the upper surface of the second portion 182 and the upper surface of the first portion 181. Subsequently, a bonding layer 190, such as an Au / In composite layer, is formed above the cladding layer 180 and then bonded to the substrate 140. Because the In metal layer has good thermal fluidity during the bonding process, it fills the height difference Δh region, forming a flat bonding surface.

[0097] like Figure 12 As shown, in this embodiment, the metal reflective layer 130 is formed by stripping the photoresist. The metal reflective layer 130 has good flatness and does not exhibit defects such as holes or edge warping that occur when using dry or wet etching. Figure 12 As shown, the metal reflective layer 130 itself has good flatness, and the coating layer 180 formed on it also has good flatness, forming a good coating effect on the metal reflective layer 130.

[0098] Example 2

[0099] This embodiment also provides a light-emitting diode, such as... Figure 13 As shown, the light-emitting diode also includes a substrate 140, a semiconductor epitaxial stack 110, a bonding layer 190 between the substrate 140 and the semiconductor epitaxial stack 110, a metal reflective layer 130 between the bonding layer 190 and the semiconductor epitaxial stack 110, and a cladding layer 180 between the metal reflective layer 130 and the bonding layer 190. The semiconductor epitaxial stack 110 can be any material capable of emitting light under voltage, such as GaN, GaAs, AlGaN, AlInP, AlGaInP, or AlGaP. Similarly, as... Figure 13 As shown, the semiconductor epitaxial stack 110 includes an N-type semiconductor layer 111, an active layer 112, and a P-type semiconductor layer 113.

[0100] The difference from other embodiments is that, as Figure 13As shown, the P-type semiconductor layer 113 of the light-emitting diode has a patterned structure on the side away from the active layer 112. Specifically, the outermost layer of the P-type semiconductor layer 113 away from the active layer 112 is a current spreading layer 115 formed by a P-type GaP layer. Part of the current spreading layer 115 is etched away to pattern the current spreading layer 115, and the remaining portion serves as the part where the P-type semiconductor layer 113 forms an electrical connection with the second electrode 152. At this time, a transparent conductive layer 153 is formed on the surface of the current spreading layer 115 and located in the region where the via 121 is located, so as to be electrically connected to the conductive pillar 160. Since the current spreading layer formed by part of the GaP layer is removed, the light absorption phenomenon caused by it can be reduced, thereby improving the light extraction efficiency of the light-emitting diode.

[0101] Example 3

[0102] This embodiment provides a light-emitting device, such as... Figure 14 As shown, the light-emitting device 300 includes a substrate 310 and a light-emitting unit 320 located above the substrate 310. A device layer 311 and an interconnect layer 312 are formed on the substrate 310. The device layer 311 includes complementary metal-oxide-semiconductor (CMOS) devices or TFT devices, which can constitute the driving circuit and control circuit of the light-emitting diode unit. The light-emitting unit is located above the substrate 310 and electrically connected to the interconnect layer 312. In this embodiment, the light-emitting unit includes any one or more light-emitting diodes provided in Embodiments 1 to 5 of this application. The light-emitting diode is electrically connected to the interconnect layer 312 through a first electrode 151 and a second electrode 152. The interconnect layer 312 is also electrically connected to the devices in the device layer 311, thereby realizing the electrical connection between the light-emitting diode and the devices, and the light-emitting diode can be controlled through the devices. Since the light-emitting device includes the light-emitting diode of this application, it also has good light emission performance.

[0103] The light-emitting device 300 may also include a housing to protect the light-emitting device from external contamination or damage, while not affecting the light emission effect of the light-emitting device, thereby improving the light emission effect and display effect of the light-emitting device.

[0104] In summary, the light-emitting diode and light-emitting device provided in this application effectively overcome the various shortcomings of the prior art and have high industrial application value.

[0105] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. A light-emitting diode, characterized in that, It includes at least a substrate, a bonding layer, a cladding layer, a metal reflective layer, and a semiconductor epitaxial stack, stacked sequentially. The coating layer is located between the metal reflective layer and the bonding layer. The metal reflective layer includes a main body portion and a trailing structure extending from the main body portion toward the edge of the light-emitting diode. The end of the trailing structure extending toward the edge of the light-emitting diode does not exceed the edge of the coating layer.

2. The light-emitting diode according to claim 1, characterized in that, The line connecting the end and the starting point of the trailing structure forms an angle α with the plane containing the surface of the metal reflective layer away from the metal bonding layer, where 5°≤α<90°, and the starting point is the junction of the trailing structure, the main body, and the covering layer.

3. The light-emitting diode according to claim 2, characterized in that, 5°≤α≤30°。 4. The light-emitting diode according to claim 1, characterized in that, The extension distance D0 of the trailing structure toward the edge of the light-emitting diode does not exceed the width W of the second part of the covering layer that covers the trailing structure.

5. The light-emitting diode according to claim 1, characterized in that, The semiconductor epitaxial stack is formed into a mesa structure, and there is a first interval distance D1 between the edge of the main part of the metal reflective layer and the edge of the mesa structure, where 1μm≤D1≤25μm.

6. The light-emitting diode according to claim 5, characterized in that, The extension distance D0 of the trailing structure toward the edge of the light-emitting diode does not exceed the first interval distance D1.

7. The light-emitting diode according to claim 1, characterized in that, The semiconductor epitaxial stack is formed into a mesa structure, and the ratio of the projected area S1 of the metal reflective layer to the projected area S2 of the mesa structure satisfies: 70% ≤ S1 / S2 < 100%.

8. The light-emitting diode according to claim 1, characterized in that, The thickness of the main portion of the metal reflective layer is between 200 Å and 6000 Å.

9. The light-emitting diode according to claim 7, characterized in that, The thickness of the trailing structure gradually increases from the edge of the light-emitting diode toward the center, and the thickness of the trailing structure is not greater than the thickness of the main body.

10. The light-emitting diode according to claim 1, characterized in that, The covering layer includes a first portion covering the main body portion and a second portion covering the trailing structure, the first portion and the second portion having the same metal layer structure.

11. The light-emitting diode according to claim 10, wherein the second portion has the same thickness as the first portion, and on the side away from the metal reflective layer, there is a height difference between the upper surface of the second portion and the upper surface of the first portion.

12. The light-emitting diode according to claim 10, characterized in that, On the side away from the metal reflective layer, the upper surface of the second portion is flush with the upper surface of the first portion.

13. The light-emitting diode according to claim 1, characterized in that, The coating layer comprises a multilayer structure formed by any of Ni, Tiw, Ti, Pt, and Au.

14. The light-emitting diode according to claim 1, characterized in that, It also includes a dielectric layer located between the semiconductor epitaxial stack and the metal reflective layer; the dielectric layer has a via, and the via is filled with the metal reflective layer.

15. The light-emitting diode according to claim 13, characterized in that, A transparent conductive layer is also present between the metal reflective layer and the semiconductor epitaxial stack within the via.

16. A light-emitting device, characterized in that, It includes a circuit board and a light-emitting element disposed on the circuit board, wherein the light-emitting element comprises a light-emitting diode as described in any one of claims 1 to 15.

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