LED chip, lighting equipment and display equipment

Abstract

The utility model provides an LED chip, lighting equipment and display equipment, and relates to the technical field of semiconductors. The second surface of the substrate is provided with a plurality of second convex structures, and the groove area between two adjacent second convex structures is equivalent to further thinning processing on the substrate, so that heat can be transmitted out through the substrate more easily, and the design also increases the contact area between the heat dissipation layer and the substrate, thereby improving the heat dissipation efficiency. And the heat dissipation performance of the LED chip is further improved to the greatest extent. The reflecting layer is arranged, so that part of light rays emitted to the direction of the substrate can be totally reflected on the interface of the substrate and the reflecting layer, and the light-emitting performance of the LED chip is improved; the first convex structures and the second convex structures which are opposite in orientation and similar to cones are arranged in one-to-one correspondence in the first direction, so that the incident angle of most of light emitted to the interface of the substrate and the reflecting layer is larger than the total reflection angle, and the light-emitting performance of the LED chip is further improved.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to an LED chip, lighting device, and display device. Background Technology

[0002] GaN-based light-emitting diodes (LEDs) are widely used in lighting and display fields due to their high photoelectric conversion efficiency, excellent color rendering, high brightness, and long lifespan. The working principle of an LED chip is that holes and electrons emit light through radiative recombination at the PN junction. During carrier recombination, non-radiative recombination inevitably occurs, generating a significant amount of heat. However, LED chips are highly sensitive to operating temperature. When the junction temperature of an LED chip rises, the device's lifespan decreases significantly, accompanied by light decay and unstable emission wavelength. Therefore, effective heat dissipation during operation is a crucial prerequisite for ensuring the normal operation of LED chips.

[0003] Thanks to the application of ITO material current spreading layers in blue LED chips, these devices often adopt a top-mounted packaging structure. The top-mounted structure offers advantages such as low cost, good light output, and simple manufacturing process, making it one of the mainstays of the industry. The structural characteristics of top-mounted LED chips mean that the sapphire substrate is bonded to the base, and the sapphire substrate has very poor thermal conductivity, which makes heat dissipation particularly difficult for high-power blue LED chips.

[0004] Currently, common methods for improving the heat dissipation capacity of LED chips mainly involve improvements in packaging materials and structures. Patent CN201520086913.X proposes fixing the LED chip to a bracket using thermally conductive insulating adhesive. The bracket then dissipates heat by contacting solder joints on the circuit board through bracket pins coated with a graphene layer. Patent CN202010553610.X proposes fixing the LED chip to a heat sink, connecting the heat sink with the LED chip fixed to a heat dissipation substrate with multiple heat dissipation holes using heat pipes, and circulating water into these heat dissipation holes. The heat from the heat sink is transferred to the heat dissipation holes through the heat pipes, and the heat is absorbed by water cooling.

[0005] However, the thermal conductivity of sapphire substrates is 20 W / m·K, which is much worse than that of silicon substrates. A large amount of heat cannot be transferred out through the sapphire substrate, and a large amount of heat is still trapped inside the LED chip, which seriously affects the stability and reliability of the device. Furthermore, the luminous performance of LED chips also needs to be improved.

[0006] Therefore, how to improve the heat dissipation and light emission performance of LED chips is a technical problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0007] In view of the above problems, this application provides an LED chip, a lighting device, and a display device to improve the heat dissipation performance and luminous performance of the LED chip. The specific solution is as follows:

[0008] A first aspect of this application provides an LED chip, the LED chip comprising:

[0009] A substrate having a first surface and a second surface disposed opposite to each other in a first direction;

[0010] An epitaxial structure is located on one side of a first surface of the substrate; the first direction is perpendicular to the plane of the substrate and points from the substrate to the epitaxial structure; the first surface of the substrate has a plurality of first protrusion structures, the size of the first protrusion structures gradually decreasing in the first direction; the second surface of the substrate has a plurality of second protrusion structures, the size of the second protrusion structures gradually decreasing in the second direction, the second direction being parallel to the first direction and pointing in opposite directions; wherein, the first protrusion structures and the second protrusion structures are arranged in a one-to-one correspondence in the first direction;

[0011] A reflective layer and a heat dissipation layer are sequentially located on one side of the second surface of the substrate, wherein the reflective layer and the heat dissipation layer at least fill the groove region between two adjacent second protrusion structures.

[0012] Preferably, in the above-mentioned LED chip, the first protrusion structure and the second protrusion structure have the same shape, which is conical.

[0013] Preferably, in the above-mentioned LED chip, the refractive index of the reflective layer is less than or equal to 1.5.

[0014] Preferably, in the above-mentioned LED chip, the thickness of the reflective layer ranges from 0.1μm to 0.5μm.

[0015] Preferably, in the above-mentioned LED chip, the thermal conductivity of the heat dissipation layer is greater than or equal to 500 W / m·K.

[0016] Preferably, in the above-mentioned LED chip, the thickness of the heat dissipation layer ranges from 1μm to 200μm.

[0017] Preferably, in the LED chip described above, the depth of the groove region between two adjacent second protrusion structures is less than the thickness of the substrate.

[0018] Preferably, in the above-mentioned LED chip, the LED chip further includes: a DBR layer located on the side of the heat dissipation layer opposite to the substrate.

[0019] A second aspect of this application provides a lighting device comprising the LED chip described in any of the preceding claims.

[0020] A third aspect of this application provides a display device, the display device comprising the LED chip described in any of the preceding claims.

[0021] By employing the above technical solutions, this application provides an LED chip, a lighting device, and a display device. The second surface of the substrate has multiple second protrusion structures. The groove region between two adjacent second protrusion structures is equivalent to further thinning the substrate, making it easier for heat to be transferred away through the substrate. This design also increases the contact area between the heat dissipation layer and the substrate, thereby maximizing the heat dissipation performance of the LED chip. By setting a reflective layer, some light rays incident on the substrate can undergo total internal reflection at the interface between the substrate and the reflective layer, improving the luminous performance of the LED chip. By arranging the first and second conical protrusion structures with opposite orientations in a one-to-one correspondence in the first direction, the incident angle of most light rays incident on the interface between the substrate and the reflective layer can be greater than the total internal reflection angle, further improving the luminous performance of the LED chip. Attached Figure Description

[0022] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0023] Figure 1 This is a schematic diagram of the structure of an LED chip provided in an embodiment of the present utility model;

[0024] Figure 2 A schematic diagram of the optical path of an LED chip with a reflective layer provided in an embodiment of this utility model;

[0025] Figure 3 A schematic diagram of the optical path of an LED chip without a reflective layer provided in an embodiment of this utility model;

[0026] Figure 4 A schematic diagram of the optical path of an LED chip having a second protrusion structure resembling a cone shape, provided for an embodiment of this utility model;

[0027] Figure 5 A schematic diagram of the optical path of an LED chip with a columnar second protrusion structure provided in an embodiment of this utility model;

[0028] Figure 6 A schematic flowchart illustrating a method for fabricating an LED chip according to an embodiment of this utility model;

[0029] Figures 7-10 for Figure 6 A partial structural schematic diagram corresponding to the preparation method shown. Detailed Implementation

[0030] The embodiments of this application are described below with reference to the accompanying drawings. The terminology used in the implementation section of this application is only for explaining specific embodiments and is not intended to limit the application. Those skilled in the art will recognize that, with technological advancements and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0031] It should be noted that the directional terms appearing in this utility model are based on the relative positional relationships shown in the accompanying drawings and should not be taken as absolute limitations on this application.

[0032] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of an LED chip provided in an embodiment of the present invention. The LED chip provided in this embodiment of the present invention includes:

[0034] Substrate 11, the substrate 11 having a first surface and a second surface disposed opposite to each other in a first direction X.

[0035] An epitaxial structure is located on one side of the first surface of the substrate 11; the first direction X is perpendicular to the plane of the substrate 11 and points from the substrate 11 to the epitaxial structure; the first surface of the substrate 11 has a plurality of first protrusion structures 12, the size of the first protrusion structures 12 gradually decreasing in the first direction X; the second surface of the substrate 11 has a plurality of second protrusion structures 13, the size of the second protrusion structures 13 gradually decreasing in the second direction Y, the second direction Y being parallel to the first direction X and pointing in opposite directions; wherein, the first protrusion structures 12 and the second protrusion structures 13 are arranged one-to-one in the first direction X. Alternatively, the first protrusion structures 12 and the second protrusion structures 13 are arranged one-to-one in the second direction Y.

[0036] A reflective layer 14 and a heat dissipation layer 15 are sequentially located on one side of the second surface of the substrate 11, and the reflective layer 14 and the heat dissipation layer 15 at least fill the groove area between two adjacent second protrusion structures 13.

[0037] Specifically, in this embodiment of the invention, the substrate 11 includes, but is not limited to, a sapphire substrate. The epitaxial structure includes at least an N-type semiconductor layer 16, a multiple quantum well layer 17, and a P-type semiconductor layer 18 sequentially stacked in a first direction X; a first groove at least penetrating the P-type semiconductor layer 18 and the multiple quantum well layer 17, the first groove exposing a portion of the surface of the N-type semiconductor layer 16. The N-type semiconductor layer 16 is an N-type doped semiconductor layer, and the P-type semiconductor layer 18 is a P-type doped semiconductor layer. For example, the N-type semiconductor layer 16 can be an N-type doped GaN layer, and the P-type semiconductor layer 18 can be a P-type doped GaN layer. It should be noted that this embodiment of the invention only uses a GaN layer as an example of a semiconductor layer; obviously, the semiconductor layer can also be a semiconductor layer of other semiconductor materials. When a GaN layer is used as the semiconductor layer, the LED chip is a GaN-based LED chip.

[0038] The core structure of an LED chip is a PN junction. When a forward bias is applied to the PN junction, electrons flow from the N-type region to the P-type region, and holes flow from the P-type region to the N-type region. These charge carriers recombine near the PN junction, releasing energy and generating photons to emit light. The multiple quantum well layer 17 is a key structure in the LED chip, its function being to improve the recombination efficiency of charge carriers and the luminous efficiency. The multiple quantum well layer 17 is composed of alternating quantum wells (QWs) and quantum barriers (QBs). Typically, the band gap of the quantum wells is smaller than that of the quantum barriers. This confines electrons and holes within the quantum wells under the influence of an external electric field, thereby increasing the recombination probability of electrons and holes and thus improving the luminous efficiency.

[0039] It should be noted that the epitaxial structure provided in this embodiment may also include other functional film layers, such as a buffer layer 19 located between the substrate 11 and the N-type semiconductor layer 16.

[0040] Optionally, the buffer layer 19 includes, but is not limited to, an AlN buffer layer with a thickness ranging from 3 nm to 50 nm. Its main function is to buffer problems such as lattice mismatch between the substrate 11 and the epitaxial structure.

[0041] Optionally, the thickness of the N-type semiconductor layer 16 ranges from 1 μm to 10 μm, and the thickness of the P-type semiconductor layer 18 is approximately 300 nm.

[0042] Optionally, the multi-quantum well layer 17 includes, but is not limited to, 3-10 cycles of InGaN / GaN layers, wherein the thickness of the InGaN layer ranges from 2nm to 10nm, and the thickness of the GaN layer ranges from 10nm to 20nm; the In composition in the InGaN layer ranges from 10% to 20%.

[0043] like Figure 1 As shown, the LED chip provided in this embodiment of the present invention further includes:

[0044] A transparent conductive layer 20 is located on the side of the P-type semiconductor layer 18 away from the substrate 11. The transparent conductive layer 20 includes, but is not limited to, an ITO layer and mainly serves to spread current.

[0045] A current blocking layer 21 is located on the side of the transparent conductive layer 20 facing the substrate 11. This current blocking layer 21 includes, but is not limited to, a SiO2 current blocking layer and mainly serves to block current. It should be noted that this current blocking layer 21 is also referred to as a CB layer in the field.

[0046] P electrode 22 connected to P-type semiconductor layer 18, and N electrode 23 connected to N-type semiconductor layer 16.

[0047] The N electrode 23 includes a Ti layer, an Al layer, a Ni layer and an Au layer stacked in the first direction X; the thickness of the Ti layer ranges from 20nm to 40nm, the thickness of the Al layer ranges from 100nm to 300nm, the thickness of the Ni layer ranges from 10nm to 50nm, and the thickness of the Au layer ranges from 50nm to 200nm.

[0048] P electrode 22 includes a Ni layer and an Au layer stacked in the first direction X; wherein the thickness of the Ni layer ranges from 20 nm to 100 nm, and the thickness of the Au layer ranges from 50 nm to 200 nm.

[0049] like Figure 1 As shown, the LED chip provided in this embodiment of the present invention further includes:

[0050] The DBR (Distributed Bragg Reflector) layer 24 is located on the side of the heat dissipation layer 15 opposite to the substrate 11.

[0051] The DBR layer 24 is used to emit light that has passed through the substrate 11 from the front of the LED chip to improve the light-emitting performance of the LED chip. This also indicates that the LED chip provided in the embodiments of this application is a front-mounted LED chip.

[0052] In this embodiment of the invention, the refractive index of the reflective layer 14 is less than or equal to 1.5. In other words, the reflective layer 14 can be understood as a low-refractive-index film layer, mainly used to reflect light incident on the substrate 11. The reflective layer 14 is prepared by, but is not limited to, a plasma-enhanced chemical vapor deposition method, and the thickness of the reflective layer 14 ranges from 0.1 μm to 0.5 μm. For example, the reflective layer 14 can be a SiO2 reflective layer.

[0053] In this embodiment of the present invention, the thermal conductivity of the heat dissipation layer 15 is greater than or equal to 500 W / m·K. The heat dissipation layer 15 can be a diamond heat dissipation layer, which is mainly used for rapid heat conduction. The heat dissipation layer 15 is prepared by microwave plasma chemical vapor deposition, and the thickness of the heat dissipation layer 15 ranges from 1 μm to 200 μm.

[0054] refer to Figure 2 , Figure 2 A schematic diagram of the optical path of an LED chip with a reflective layer provided in an embodiment of this utility model is shown below. Figure 3 , Figure 3 This is a schematic diagram of the optical path of an LED chip without a reflective layer, provided as an embodiment of the present invention.

[0055] Since the light-emitting surface of the upright LED chip is the side with the epitaxial structure, it is desirable that as much light incident on the substrate 11 as possible is reflected back to the front surface for emission. In comparison, since each film layer absorbs light to a certain extent, such as... Figure 2 As shown in this embodiment of the invention, when a low-refractive-index reflective layer 14 is inserted, compared to... Figure 3 The structure shown allows light emitted from the substrate 11 at angles greater than the critical angle to undergo total internal reflection, thus preventing absorption by the materials of the heat dissipation layer 15 and the DBR layer 24, thereby improving the light-emitting performance of the LED chip.

[0056] In other words, the LED chip provided in this embodiment of the present invention improves the light-emitting performance of the LED chip by setting a reflective layer 14 so that some of the light rays incident on the substrate 11 can undergo total internal reflection at the interface between the substrate 11 and the reflective layer 14. The provision of a heat dissipation layer 15 further improves the heat dissipation performance of the LED chip.

[0057] refer to Figure 4 , Figure 4 A schematic diagram of the optical path of an LED chip with a second conical protrusion structure provided for an embodiment of this utility model is shown below. Figure 5 , Figure 5 This is a schematic diagram of the optical path of an LED chip with a columnar second protrusion structure provided in an embodiment of the present invention.

[0058] First, the second surface of the substrate 11 has multiple second protrusion structures 13. The groove area between two adjacent second protrusion structures 13 is equivalent to further thinning the substrate 11, making it easier for heat to be transferred out through the substrate 11. This design also increases the contact area between the heat dissipation layer 15 and the substrate 11, thereby maximizing the heat dissipation performance of the LED chip.

[0059] Secondly, looking at it in a comparative way, such as Figure 4 The diagram shows a first and second cone-shaped protrusion structure 12 and a second protrusion structure 13 facing opposite directions, and they are arranged one-to-one in the first direction X. Figure 5 The structure shown allows most of the light rays incident on the interface between the substrate 11 and the reflective layer 14 to have an incident angle greater than the total internal reflection angle, thereby further improving the light-emitting performance of the LED chip. In other words, with the reflective layer 14 provided, this embodiment of the invention can further optimize the morphology of the second surface of the substrate 11 to further improve the light-emitting performance of the LED chip.

[0060] Optionally, the first protrusion structure 12 and the second protrusion structure 13 have the same shape, which is conical. The depth of the groove region between two adjacent second protrusion structures 13 is less than the thickness of the substrate 11, so as to avoid this design from affecting the strength of the substrate 11, ensuring the structural stability of the substrate 11, and thus ensuring the structural stability of the LED chip.

[0061] In summary, the LED chip provided by this embodiment improves the second surface of the substrate 11 by giving it multiple second protrusion structures 13. The groove area between two adjacent second protrusion structures 13 is equivalent to further thinning the substrate 11, making it easier for heat to be transferred away through the substrate 11. This design also increases the contact area between the heat dissipation layer 15 and the substrate 11, thereby maximizing the heat dissipation performance of the LED chip. By setting the reflective layer 14, some of the light rays incident on the substrate 11 can undergo total internal reflection at the interface between the substrate 11 and the reflective layer 14, improving the light-emitting performance of the LED chip. By setting the first and second protrusion structures 12 and 13, which are similar to cones with opposite orientations, in a one-to-one correspondence in the first direction X, the incident angle of most of the light rays incident on the interface between the substrate 11 and the reflective layer 14 is greater than the total internal reflection angle, thereby further improving the light-emitting performance of the LED chip.

[0062] Based on the above embodiments of this utility model, another embodiment of this utility model also provides a method for preparing an LED chip, see reference. Figure 6 , Figure 6 This is a schematic flowchart illustrating a method for fabricating an LED chip according to an embodiment of the present invention. The method for fabricating an LED chip according to an embodiment of the present invention includes:

[0063] S101: As Figure 7 As shown, a substrate 11 is provided, the substrate 11 having a first surface and a second surface disposed opposite to each other in a first direction X.

[0064] Specifically, in this step, the first surface of the substrate 11 has a plurality of first protrusion structures 12, the size of the first protrusion structures 12 gradually decreasing in the first direction X.

[0065] S102: As Figure 8 As shown, an epitaxial structure is formed on one side of the first surface of the substrate 11; the first direction X is perpendicular to the plane where the substrate 11 is located and points from the substrate 11 to the epitaxial structure.

[0066] Specifically, this step includes, but is not limited to, using processes such as MOCVD (Metal-organic Chemical Vapor Deposition) and micro / nano semiconductor fabrication techniques to prepare the desired epitaxial structure.

[0067] S103: As Figure 9 As shown, substrate 11 is thinned. That is, there is a relationship H1 > H2. The thickness of the thinned substrate 11 ranges from 50 μm to 100 μm.

[0068] S104: As Figure 10 As shown, the second surface of the substrate 11 is processed to give the second surface of the substrate 11 a plurality of second protrusion structures 13, the size of the second protrusion structure 13 gradually decreases in the second direction Y, the second direction Y is parallel to the first direction X and they point in opposite directions.

[0069] Specifically, in this step, the first protrusion structure 12 and the second protrusion structure 13 are arranged in a one-to-one correspondence in the first direction X.

[0070] S105: As Figure 1 As shown, a reflective layer 14, a heat dissipation layer 15, and a DBR layer 24 are sequentially formed on one side of the second surface of the substrate 11. The reflective layer 14 and the heat dissipation layer 15 at least fill the groove region between two adjacent second protrusion structures 13.

[0071] Based on the above embodiments of the present invention, another embodiment of the present invention also provides a lighting device, which includes the LED chip described in the above embodiments.

[0072] Based on the above embodiments of the present invention, another embodiment of the present invention also provides a display device, the display device including the LED chip described in the above embodiments.

[0073] The present invention provides a detailed description of an LED chip, lighting device, and display device. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

[0074] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0075] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that elements inherent to a process, method, article, or apparatus that comprises a list of elements, or elements inherent to such processes, methods, articles, or apparatus, are also included. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0076] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those 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 to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An LED chip, characterized in that, The LED chip includes: A substrate having a first surface and a second surface disposed opposite to each other in a first direction; An epitaxial structure is located on one side of a first surface of the substrate; the first direction is perpendicular to the plane of the substrate and points from the substrate to the epitaxial structure; the first surface of the substrate has a plurality of first protrusion structures, the size of the first protrusion structures gradually decreasing in the first direction; the second surface of the substrate has a plurality of second protrusion structures, the size of the second protrusion structures gradually decreasing in the second direction, the second direction being parallel to the first direction and pointing in opposite directions; wherein, the first protrusion structures and the second protrusion structures are arranged in a one-to-one correspondence in the first direction; A reflective layer and a heat dissipation layer are sequentially located on one side of the second surface of the substrate, wherein the reflective layer and the heat dissipation layer at least fill the groove region between two adjacent second protrusion structures.

2. The LED chip according to claim 1, characterized in that, The first protrusion structure and the second protrusion structure have the same shape, which is conical.

3. The LED chip according to claim 1, characterized in that, The refractive index of the reflective layer is less than or equal to 1.

5.

4. The LED chip according to claim 1, characterized in that, The thickness of the reflective layer ranges from 0.1 μm to 0.5 μm.

5. The LED chip according to claim 1, characterized in that, The thermal conductivity of the heat dissipation layer is greater than or equal to 500 W / m·K.

6. The LED chip according to claim 1, characterized in that, The thickness of the heat dissipation layer ranges from 1μm to 200μm.

7. The LED chip according to claim 1, characterized in that, The depth of the groove region between two adjacent second protrusion structures is less than the thickness of the substrate.

8. The LED chip according to any one of claims 1-7, characterized in that, The LED chip also includes: The DBR layer is located on the side of the heat dissipation layer opposite to the substrate.

9. A lighting device, characterized in that, The lighting device includes the LED chip according to any one of claims 1-8.

10. A display device, characterized in that, The display device includes the LED chip according to any one of claims 1-8.

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