LED chip

Abstract

The LED chip comprises a light-emitting structure, an ohmic contact layer, a first electrode and a second electrode, the light-emitting structure comprises a first type semiconductor layer, an active layer and a second type semiconductor layer which are stacked in sequence; one side surface, close to the second-type semiconductor layer, of the light-emitting structure forms a light-emitting surface; the ohmic contact layer is located on the light-emitting surface and provided with a plurality of through holes exposed out of the light-emitting surface, and the through holes are distributed at intervals; the first electrode is electrically connected with the first type semiconductor layer; the second electrode is electrically connected with the second type semiconductor layer; the second electrode comprises a PAD electrode and a plurality of expansion electrodes; the PAD electrode is located on the surface of the ohmic contact layer deviating from the light-emitting surface; the extension electrodes are embedded into the through holes in a one-to-one correspondence manner; and the Ohmic contact layer conducts the PAD electrode and the extension electrode. According to the LED chip, on the basis that current expansion is not affected, the proportion of the electrodes on the surface of the light emitting side of the chip is reduced, and the electrodes are not prone to falling off.

Description

Technical Field

[0001] The present invention relates to the technical field of light emitting diodes, and more particularly to an LED chip. Background Art

[0002] With the continuous development of science and technology, LED (Light Emitting Diode) as a new type of light-emitting device, compared with traditional light-emitting devices, LED chips have many advantages such as low power consumption, high color purity, long life, small size, fast response time, energy saving and environmental protection. It has become the most popular light source at present, with an increasing market share and a wider range of applications.

[0003] Chips with different structures (e.g., face-mounted, reverse polarity, and flip-chip) almost all encounter the problems of poor current spreading and absorption of emitted light by electrodes, resulting in suboptimal luminous intensity of the LED chip. Common solutions adopted in the industry include: 1. Preparing structures such as a Bragg distributed reflector (DBR) or an omnidirectional reflector (ODR) on the non-light-emitting side to increase the chip's light extraction efficiency by reflecting the non-emitted light. 2. Enhancing the current spreading capability by designing different electrode structures on the light-emitting surface. For example, by designing the electrode grid lines to be thinner, smaller, and fewer, the electrode can minimize the obstruction of the active layer's emitted light and increase the light extraction efficiency. However, the traditional distribution of electrode grid lines on the light-emitting surface still occupies a large portion of the chip's effective light-emitting area, thereby reducing the chip's light extraction efficiency. Moreover, in order to achieve better current spreading, it is usually necessary to design a relatively precise continuous pattern, which is complex to process and requires high precision from the machine. In addition, in order to minimize the obstruction of the outgoing light, the electrode grid lines are designed to be as thin as possible, which greatly affects the firmness of the grid lines and increases the risk of the electrode grid lines falling off.

[0004] This case was created to solve the problem of the above-mentioned electrodes occupying a large light-emitting area and falling off. Summary of the Invention

[0005] In view of this, the present invention provides an LED chip, which reduces the proportion of the electrode on the light-emitting side surface of the chip without affecting the current expansion, and the electrode is not easy to fall off.

[0006] To achieve the above-mentioned object, the technical solution adopted by the present invention is as follows: an LED chip, comprising: a light-emitting structure, an ohmic contact layer, a first electrode and a second electrode;

[0007] The light emitting structure comprises a first-type semiconductor layer, an active layer, and a second-type semiconductor layer stacked in sequence; a surface of the light emitting structure close to the second-type semiconductor layer forms a light emitting surface;

[0008] The ohmic contact layer is located on the light emitting surface and is provided with a plurality of through holes exposing the light emitting surface, and the through holes are arranged at intervals;

[0009] The first electrode is electrically connected to the first-type semiconductor layer;

[0010] The second electrode is electrically connected to the second-type semiconductor layer; the second electrode includes a PAD electrode and a plurality of extended electrodes; the PAD electrode is located on the surface of the ohmic contact layer away from the light-emitting surface; the extended electrodes are embedded in each of the through holes one by one; the ohmic contact layer conducts the PAD electrode and the extended electrodes.

[0011] Furthermore, the ohmic contact layer is provided with at least one through-hole group; each through-hole group is provided with at least one through-hole; when each through-hole group is provided with a plurality of through-holes, each through-hole is spaced apart in a direction away from the PAD electrode.

[0012] Furthermore, when there are multiple through hole groups, each through hole group is evenly arranged around the PAD electrode.

[0013] Furthermore, the through holes of each through hole group are arranged along a straight line.

[0014] Furthermore, a spacing distance L between each of the through holes in each of the through hole groups is 2 μm-12 μm, including endpoint values.

[0015] Furthermore, the spacing distances L between the through holes in each through hole group are equal or unequal.

[0016] Furthermore, a spacing distance L between the through holes in each through hole group gradually decreases in a direction away from the PAD electrode.

[0017] Furthermore, the thickness of the ohmic contact layer is greater than or equal to 70 nm, including the endpoint value.

[0018] Furthermore, the ohmic contact layer is provided with a roughened structure on the surface between the through holes.

[0019] Furthermore, it also includes a first-type current spreading layer, a dielectric film layer, a metal reflective layer, a metal bonding layer, and a substrate, which are located on the surface of the first-type semiconductor layer away from the active layer and are arranged in sequence away from the first-type semiconductor layer; a conductive hole is provided on the dielectric film layer, and a conductive metal that conducts the metal reflective layer and the first-type current spreading layer is provided in the conductive hole; the first electrode is provided on the surface of the substrate away from the metal reflective layer; it also includes a second-type current spreading layer and a second-type roughening layer, which are located on the surface of the second-type semiconductor layer away from the active layer and are arranged in sequence away from the second-type semiconductor layer; the ohmic contact layer is located on the second-type roughening layer.

[0020] Compared with the existing technology, the technical solution provided by the present invention has at least the following advantages:

[0021] 1. An LED chip comprising: a light-emitting structure, an ohmic contact layer, a first electrode, and a second electrode; the light-emitting structure comprising a first-type semiconductor layer, an active layer, and a second-type semiconductor layer stacked in sequence; a light-emitting surface is formed on a surface of the light-emitting structure close to the second-type semiconductor layer; the ohmic contact layer is located on the light-emitting surface and is provided with a plurality of through holes exposing the light-emitting surface, and the through holes are arranged at intervals; the first electrode is electrically connected to the first-type semiconductor layer; the second electrode is electrically connected to the second-type semiconductor layer; the second electrode comprises a PAD electrode and a plurality of extended electrodes; the PAD electrode is located on a surface of the ohmic contact layer facing away from the light-emitting surface; the extended electrodes are embedded in each through hole in a one-to-one correspondence; the ohmic contact layer conducts electricity between the PAD electrode and the extended electrodes. Due to the above-mentioned structural arrangement, the LED chip of the present application divides the second electrode into two parts, the PAD electrode and the extended electrode, and the PAD electrode can ensure ohmic contact between the second electrode and the second-type semiconductor layer; the extended electrode is only provided in the through hole, which reduces the area occupied by the electrode on the chip's light-emitting surface, thereby reducing the electrode's shielding of the emitted light and improving the light extraction efficiency of the LED chip. The ohmic contact layer provides electrical connection between the PAD electrode and the extended electrode, allowing the discontinuous extended electrode to more flexibly direct the current flow from the PAD electrode, providing a larger and more uniform current spreading performance and reducing current crowding beneath the electrode. Furthermore, embedding the extended electrode within the through-hole effectively eliminates the risk of existing thin electrode grid lines falling off, enhancing the electrode's robustness.

[0022] 2. The through holes in the through hole group are arranged at intervals in a direction away from the PAD electrode, inducing the current flowing up and down the PAD electrode to spread along the arrangement direction of the through holes, making the current spread more uniform.

[0023] 3. Each through-hole group is evenly arranged around the PAD electrode, making the current spread more uniform.

[0024] 4. The surface between each through hole is provided with a roughened structure, which further increases the effective light-emitting area and improves the light intensity of the LED. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0026] Figure 1 Schematic diagram of the existing electrode structure of LED chips;

[0027] Figure 2 for Figure 1 Schematic top view of

[0028] Figure 3 This is a schematic structural diagram of an embodiment of an LED chip in this application;

[0029] Figure 4 for Figure 3 Schematic diagram of the top view structure;

[0030] Figure 5 Schematic diagram of the structure of the ohmic contact layer in this application;

[0031] Figure 6 This is a schematic structural diagram of another embodiment of the LED chip in this application;

[0032] Figure 7 for Figure 6 Schematic diagram of the top view structure;

[0033] Figure 8 This is a schematic structural diagram of another embodiment of the LED chip in this application.

[0034] Reference numerals:

[0035] First-type semiconductor layer 1; active layer 2; second-type semiconductor layer 3; ohmic contact layer 4; through-hole group 41; through-hole 411; first electrode 5; second electrode 6; PAD electrode 61; extended electrode 62; first-type current spreading layer 7; dielectric film layer 8; metal reflective layer 9; metal bonding layer 10; substrate 11; conductive metal 12; second-type current spreading layer 13; second-type roughening layer 14. DETAILED DESCRIPTION

[0036] To make the content of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0037] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0038] Secondly, this application is described in detail with reference to schematic diagrams. When describing the embodiments of this application, for ease of explanation, cross-sectional views of device structures may be partially enlarged and not to scale. Furthermore, these schematic diagrams are merely illustrative and should not limit the scope of protection of this application. Furthermore, in actual production, three-dimensional dimensions, including length, width, and depth, should be included.

[0039] like Figure 1 、 2 As shown, the existing LED chip electrodes include PAD electrodes 61 and electrode grid lines (i.e. Figure 2 The extended electrode 62 in the chip). The thinner, smaller, and fewer electrode grid lines are designed, the less likely the electrode blocks the light emitted from the active layer, thereby increasing the light extraction rate. However, the traditional distribution of electrode grid lines on the light-emitting surface still occupies a large effective light-emitting area of ​​the chip, thereby reducing the light extraction efficiency of the chip. Moreover, in order to obtain better current expansion, it is usually necessary to design a more precise continuous pattern, which is complex in process and requires a high precision of the machine. In addition, in order to minimize the blockage of the emitted light, the electrode grid lines are designed to be as thin as possible, which greatly affects the firmness of the electrode grid lines and increases the risk of the electrode grid lines falling off.

[0040] In order to solve the problem that the above-mentioned electrodes occupy a large light-emitting area and fall off, the present application provides an LED chip, which includes a light-emitting structure, an ohmic contact layer 4, a first electrode 5 and a second electrode 6.

[0041] like Figure 3 、 4 As shown in Figures 5 and 6, the light-emitting structure includes a first-type semiconductor layer 1, an active layer 2, and a second-type semiconductor layer 3 stacked in sequence; a light-emitting surface is formed on the surface of the light-emitting structure adjacent to the second-type semiconductor layer 3. The light-emitting surface can be the surface of the second-type semiconductor layer 3 facing away from the active layer 2, or it can be the surface of other functional layers located on the second-type semiconductor layer 3 facing away from the active layer 2. One of the first-type semiconductor layer 1 and the second-type semiconductor layer 3 is an N-type semiconductor layer, and the other is a P-type semiconductor layer. In this application, the first-type semiconductor layer 1 is a P-type semiconductor layer, and the second-type semiconductor layer 3 is an N-type semiconductor layer.

[0042] The ohmic contact layer 4 is located on the light emitting surface and is provided with a plurality of through holes 411 exposed to the light emitting surface. The through holes 411 are arranged at intervals.

[0043] The first electrode 5 is electrically connected to the first-type semiconductor layer 1 .

[0044] The second electrode 6 is electrically connected to the second-type semiconductor layer 3 and includes a pad electrode 61 and a plurality of extension electrodes 62. The pad electrode 61 is located on the surface of the ohmic contact layer 4 facing away from the light-emitting surface. The extension electrodes 62 are embedded in each through hole 411 in a one-to-one correspondence. The ohmic contact layer 4 provides electrical conduction between the pad electrode 61 and the extension electrodes 62.

[0045] Due to the above-mentioned structural setting, the LED chip of the present application divides the second electrode into two parts, the PAD electrode and the extended electrode. The PAD electrode 61 can ensure the ohmic contact between the second electrode 6 and the semiconductor layer; the extended electrode 62 is only arranged in the through hole 411, which reduces the area ratio of the electrode on the light-emitting surface of the chip, thereby reducing the electrode's shielding of the emitted light and improving the light-emitting efficiency of the LED chip. The ohmic contact layer 4 conducts the PAD electrode 61 and the extended electrode 62, so that the discontinuous extended electrode 62 can more flexibly induce the direction of the current conducted by the PAD electrode 61, provide a larger area and more uniform current expansion performance, and improve the current crowding under the electrode. In addition, the embedded extended electrode 62 in the through hole 411 effectively avoids the risk of the existing small electrode grid line falling off and enhances the firmness of the electrode.

[0046] The cross-sectional shape of the extended electrode 62 (i.e., the cross-sectional shape of the through-hole 411) can be regular or irregular, such as rectangular or circular, or a combination thereof; the size of each extended electrode 62 can be uniform or inconsistent. In this application, the upper surface of the extended electrode 62 is flush with the upper surface of the ohmic contact layer 4, and the lower surface contacts the light-emitting surface to achieve electrical connection with the second-type semiconductor layer 3. The cross-sectional shape of the PAD electrode is not limited to the circular shape shown in the figure; other shapes are also possible.

[0047] Preferably, if Figure 3 、 4 As shown in Figures 5 and 6, the ohmic contact layer 4 is provided with at least one through-hole group 41; each through-hole group 41 is provided with at least one through-hole 411; when each through-hole group 41 is provided with a plurality of through-holes 411, each through-hole 411 is spaced apart in a direction away from the PAD electrode 61, inducing the current flowing up and down the PAD electrode 61 to expand along the arrangement direction of the through-holes 411, and the current expansion is more uniform. In the present application, the through-holes 411 of each through-hole group 41 on the ohmic contact layer 4 are spaced apart in a direction away from the PAD electrode 61, with the area where the PAD electrode 61 is provided as the base point. Exemplarily, in the present application, the through-hole 411 closest to the PAD electrode 61 in each through-hole group 41 is spaced apart from the PAD electrode 61, but in other embodiments, the through-hole closest to the PAD electrode can also be provided close to the PAD electrode 61.

[0048] Furthermore, when there are multiple through-hole groups 41 , each through-hole group 41 is evenly arranged around the PAD electrode 61 , so that the current spreads more evenly. Figure 5 As shown exemplarily, the LED chip has four through hole groups 41, each of which is provided with three through holes 411; in actual use, the number of through hole groups 41 and the number of through holes 411 in each through hole group 41 can be set according to specific needs.

[0049] Furthermore, the through holes 411 of each through hole group 41 are arranged along a straight line, which is beneficial to current expansion.

[0050] Preferably, if Figure 5 As shown, the spacing distance L between the through holes 411 in each through hole group 41 is 2 μm to 12 μm, inclusive. For example, the spacing between the through holes 411 can be 2 μm, 4 μm, 9 μm, 12 μm, etc. Excessive spacing can affect the current spreading effect. Therefore, by setting an appropriate spacing distance L, the current flowing out of the PAD electrode can be better spread.

[0051] Preferably, the spacing distances L between the through holes 411 in each through hole group 41 are equal or unequal. Figure 3 、 4 The example shows the case where the spacing distance L is equal. Figure 6 、 7 The case where the spacing distances L are not equal is shown as an example.

[0052] Further, when the spacing distances L between the through holes 411 in the through hole groups 41 are not equal, the spacing distances L between the through holes 411 in the through hole groups 41 may be set to gradually decrease in a direction away from the PAD electrode 61 .

[0053] The spacing distances L between the through holes 411 in the through hole groups 41 may be equal or unequal and may be selected within the range of 2 μm to 12 μm (including the end points).

[0054] Preferably, the thickness of the ohmic contact layer 4 is greater than or equal to 70 nm, inclusive. For example, it can be 70 nm, 80 nm, 95 nm, 100 nm, etc. Setting an appropriate thickness of the ohmic contact layer 4 can better spread the current flowing out of the PAD electrode.

[0055] Preferably, if Figure 8 As shown, the ohmic contact layer 4 is provided with a roughened structure on the surface between the through holes 411, which further increases the effective light-emitting area and improves the light intensity of the LED.

[0056] Preferably, taking a red LED chip as an example, Figure 3As shown, the LED chip also includes a first-type current spreading layer 7, a dielectric film layer 8, a metal reflective layer 9, a metal bonding layer 10, and a substrate 11, which are located on the surface of the first-type semiconductor layer 1 away from the active layer 2 and are sequentially arranged along the surface away from the first-type semiconductor layer 1; a conductive hole is provided on the dielectric film layer 8, and a conductive metal 12 is provided in the conductive hole to conduct electricity between the metal reflective layer 9 and the first-type current spreading layer 7; a first electrode 5 is provided on the surface of the substrate 11 away from the metal reflective layer 9; and the chip also includes a second-type current spreading layer 13 and a second-type roughening layer 14, which are located on the surface of the second-type semiconductor layer 3 away from the active layer 2 and are sequentially arranged along the surface away from the second-type semiconductor layer 3; and an ohmic contact layer 4 is located on the second-type roughening layer 14. That is, the LED chip comprises, from bottom to top, the following: first electrode 5, substrate 11, metal bonding layer 10, metal reflective layer 9, dielectric film layer 8, first-type current spreading layer 7, first-type semiconductor layer 1, active layer 2, second-type semiconductor layer 3, second-type current spreading layer 13, second-type roughening layer 14, ohmic contact layer 4, and second electrode 6. The surface of the second-type roughening layer facing away from the active layer 2 is the light-emitting surface.

[0057] In the present application, the first-type current spreading layer can be a P-GaP layer to ensure current spreading and ohmic contact on the P surface, the first-type semiconductor layer can be a P-Al InP limiting layer, the second-type semiconductor layer can be an N-Al InP limiting layer, the second-type current spreading layer can be N-Al Ga InP, the second-type roughening layer can be an N-Al Ga InP roughening layer, the ohmic contact layer 4 can be N-GaAs, the dielectric film layer can be SiO2, the metal reflector can be Ag or Au, and the metal bonding layer can be Au-Au or Au-In.

[0058] Among them, this application only uses the structure of the red light LED chip as an example for explanation, but the structure of the LED chip is not limited to this; for example, the chip type can be a blue-green light LED chip, a deep ultraviolet LED chip, etc.; the chip structure can be a vertical structure, a reverse polarity structure, a horizontal structure, a face-up structure, a flip-chip structure, etc.

[0059] Taking a red light emitting diode as an example, the manufacturing process of the LED chip of this application is described as follows:

[0060] An N-GaAs buffer layer, an N-GaInP etching stop layer, an N-GaAs ohmic contact layer, a NAlGaInP roughening layer, an N-AlGaInP current spreading layer, an N-AlInP confinement layer, an active layer, a PAlInP confinement layer, and a P-GaP layer are sequentially epitaxially grown on a GaAs growth substrate by using a metal organic compound vapor deposition (MOCVD) method to obtain a corresponding epitaxial wafer.

[0061] A dielectric film layer is sequentially evaporated onto the P-GaP layer on the epitaxial wafer surface. Conductive holes are then machined in the dielectric film layer, and conductive metal is fabricated within the conductive holes. After evaporating a metal reflective layer onto the dielectric film layer, a substrate is bonded to one side of the metal reflective layer. The N-face GaAs growth substrate, N-GaAs buffer layer, and N-Ga InP etching stop layer are sequentially removed to expose the N-GaAs ohmic contact layer. Through holes 411 are then formed in the N-GaAs ohmic contact layer as required, followed by the fabrication of the PAD electrode and extension electrode for the second electrode. The first electrode is fabricated on the surface of the substrate facing away from the active layer.

[0062] It should be understood by those skilled in the art that, in the disclosure of the present invention, the terms "horizontal", "vertical", "upper", "lower", etc. indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms cannot be understood as limiting the present invention.

[0063] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other.

[0064] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An LED chip, characterized in that: include: a light emitting structure, an ohmic contact layer, a first electrode and a second electrode; The light emitting structure comprises a first-type semiconductor layer, an active layer, and a second-type semiconductor layer stacked in sequence; a surface of the light emitting structure close to the second-type semiconductor layer forms a light emitting surface; The ohmic contact layer is located on the light emitting surface and is provided with a plurality of through holes exposing the light emitting surface, and the through holes are arranged at intervals; The first electrode is electrically connected to the first-type semiconductor layer; The second electrode is electrically connected to the second-type semiconductor layer; the second electrode includes a PAD electrode and a plurality of extended electrodes; the PAD electrode is located on a surface of the ohmic contact layer away from the light-emitting surface; The extended electrodes are embedded in the through holes in a one-to-one correspondence; the ohmic contact layer conducts between the PAD electrodes and the extended electrodes.

2. The LED chip according to claim 1, wherein: The ohmic contact layer is provided with at least one through-hole group; each through-hole group is provided with at least one through-hole; when each through-hole group is provided with a plurality of through-holes, the through-holes are spaced apart in a direction away from the PAD electrode.

3. The LED chip according to claim 2, wherein: When there are multiple through hole groups, each through hole group is evenly arranged around the PAD electrode.

4. The LED chip according to claim 2, wherein: The through holes of each through hole group are arranged along a straight line.

5. The LED chip according to claim 2, wherein: The spacing distance L between each of the through holes in each of the through hole groups is 2 μm to 12 μm, inclusive.

6. The LED chip according to claim 2, wherein: The spacing distances L between the through holes in each through hole group are equal or unequal.

7. The LED chip according to claim 2, wherein: The spacing distance L between the through holes in each through hole group gradually decreases in a direction away from the PAD electrode.

8. The LED chip according to claim 1, wherein: The thickness of the ohmic contact layer is greater than or equal to 70 nm, including the end point value.

9. The LED chip according to claim 1, wherein: The ohmic contact layer is provided with a roughened structure on a surface spaced between the through holes.

10. The LED chip according to claim 1, wherein: The invention also includes a first-type current spreading layer, a dielectric film layer, a metal reflective layer, a metal bonding layer, and a substrate, which are located on a surface of the first-type semiconductor layer away from the active layer and are sequentially arranged away from the first-type semiconductor layer; a conductive hole is provided on the dielectric film layer, and a conductive metal is provided in the conductive hole to conduct electricity between the metal reflective layer and the first-type current spreading layer; the first electrode is provided on a surface of the substrate away from the metal reflective layer; It also includes a second-type current spreading layer and a second-type roughening layer located on a surface of the second-type semiconductor layer away from the active layer and sequentially arranged away from the second-type semiconductor layer; the ohmic contact layer is located on the second-type roughening layer.

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