MicroLED packaging structure containing color conversion layer

Abstract

The invention relates to the technical field of semiconductor display, and discloses a MicroLED packaging structure containing a color conversion layer, the MicroLED packaging structure comprises a bottom layer and a plurality of LED crystals, the top of the bottom layer is provided with a first packaging layer, the first packaging layer is internally provided with a plurality of conductive blocks, one side of each LED crystal is fixedly connected to the outer side of the corresponding conductive block, and the other side of each LED crystal is fixedly connected to the outer side of the corresponding conductive block. A packaging layer is arranged outside the first packaging layer and the LED crystal, a contact layer is arranged outside the packaging layer, a flat layer is arranged outside the packaging layer and the contact layer, a color conversion layer is arranged outside the flat layer, and a plurality of light blocking blocks are installed in the color conversion layer. The vertical blue light efficiently excites the color conversion layer, so that the color conversion layer fully converts the blue light into light of other colors, light transmission loss is reduced, the effect of higher brightness is achieved under the condition that an LED with a smaller size is adopted, display performance is greatly improved, and powerful support is provided for miniaturization and high performance of a display product.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor display technology, and in particular to a MicroLED packaging structure containing a color conversion layer. Background Art

[0002] With the rapid development of display technology, MicroLED, with its numerous advantages such as high brightness, high contrast, low power consumption, and long life, has become a highly promising technology in the display field. As a key component in achieving MicroLED display performance, MicroLED packaging structures have long been a focus of research and development. While traditional MicroLED packaging structures meet display needs, they also face the challenge of continuously improving performance and reducing costs. With the consumer market's increasing demand for thinner, smaller, and higher-resolution display products, optimizing MicroLED packaging structures has become increasingly urgent.

[0003] MicroLED packaging structures in existing technologies are typically implemented using a variety of materials and processes. For example, sapphire is used as a substrate for epitaxial growth of MicroLED chips, the chips are connected to conductive structures through metal welding and other methods, and then different packaging layers and protective structures are used to ensure the normal operation and stability of the chips. In terms of color realization, AlGaInP materials are often used to achieve red light display. Its principle is based on the luminescence characteristics of semiconductor materials, and the recombination of electrons and holes produces light of a specific wavelength. At the same time, in order to ensure the propagation and display effect of light, filters, light blocks and other structures are also set to control the propagation path and color purity of the light.

[0004] In practical applications, as microLED device size continues to decrease, the drawbacks of existing technologies are becoming increasingly apparent. For example, in wearable devices such as smartwatches, achieving higher resolution and a more compact design requires the use of smaller microLED devices. However, the efficiency of traditional AlGaInP red LEDs decreases significantly as device size decreases. This is because the quantum efficiency and carrier recombination efficiency of the AlGaInP material are affected at small sizes, resulting in reduced luminous efficiency. Furthermore, achieving red light using a blue microLED plus red quantum dots approach presents new challenges. As blue LED device size decreases and flip-chip pads become smaller than 10µm, soldering and wiring become extremely difficult. For example, in high-definition display devices such as mobile phones, increasing screen pixel density requires the use of smaller blue LEDs. However, due to the small size of flip-chip pads, traditional soldering processes struggle to ensure reliable electrical connections, making cold solder joints and short circuits more likely to occur. Furthermore, the reduced wiring space complicates circuit design, leading to reduced production efficiency and increased costs. Therefore, the present invention provides a MicroLED packaging structure including a color conversion layer to address the deficiencies in the prior art. Summary of the Invention

[0005] In response to the shortcomings of the prior art, the present invention provides a MicroLED packaging structure containing a color conversion layer, which solves the problem of reduced luminous efficiency due to reduced device size in the prior art MicroLED packaging structure.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: A MicroLED packaging structure containing a color conversion layer, comprising a bottom layer and multiple LED crystals, a packaging layer 1 is provided on the top of the bottom layer, a plurality of conductive blocks are provided inside the packaging layer 1, one side of the LED crystal is fixedly connected to the outside of the conductive block, a wrapping layer is provided outside the packaging layer 1 and the LED crystal, a contact layer is provided outside the wrapping layer, a flat layer is provided outside the packaging layer and the contact layer, a color conversion layer is provided outside the flat layer, a plurality of light blocking blocks are installed inside the color conversion layer, and one end of the light blocking block is bonded to the outside of the flat layer, a packaging layer 2 is provided between the light blocking block and the other end and the outside of the color conversion layer, a filter 1 and a filter 2 are provided outside the packaging layer 2, and a packaging layer 3 is provided outside the packaging layer 2, the filter 1 and the filter 2.

[0007] Preferably, the conductive block is made of copper and is used to provide current to the LED crystal.

[0008] Preferably, the LED crystal is a composite material, comprising metal, ITO, p+-GaN, MQW, n+-GaN and u-GaN.

[0009] Preferably, the material of the wrapping layer is SiO or SiN, or a stacked structure of the two.

[0010] Preferably, the contact layer is used for ohmic contact, and the material of the contact layer is ITO.

[0011] Preferably, the material of the planar layer is organic matter, which is used for planarization and insulation.

[0012] Preferably, the light blocking block is black photoresist for absorbing and blocking light.

[0013] Preferably, the materials of the encapsulation layer 1, the encapsulation layer 2 and the encapsulation layer 3 are all silicon nitride, aluminum oxide or a composite material thereof, which is used to prevent water vapor and oxygen from corroding other structures.

[0014] Preferably, the colors of the first filter and the second filter are different, so as to shield the blue light that is not completely converted.

[0015] A method for packaging a MicroLED with a color conversion layer, applied to the aforementioned MicroLED packaging structure with a color conversion layer, comprises the following steps: S1. Remove the used MicroLED from the sapphire using laser lift-off technology; S2. Solder the MicroLED to the conductive block by AuSn eutectic welding, AuIn eutectic welding, or ACF welding. S4, thinning the u-GaN and n+-GaN parts of the LED crystal and wrapping them with a PV wrapping layer; S5. Digging holes outside the wrapping layer to make ohmic contacts with the contact layer, and then covering with a flat layer to protect the circuit structure; S6. Setting a light blocking block outside the flat layer to absorb and block light; S7. Place a color conversion layer outside the light blocking block, the color conversion layer being a quantum dot material or a phosphor material, and then encapsulate it with a second encapsulation layer; S8. Filters 1 and 2 are set outside the encapsulation layer 2 to shield the blue light that is not completely converted, and then the encapsulation layer 3 is used to cover it, thus completing the encapsulation operation of the entire structure.

[0016] The present invention provides a MicroLED packaging structure including a color conversion layer. It has the following beneficial effects: 1. The present invention adopts a vertical blue light + color conversion structure solution. In the entire packaging process, from laser stripping to optimize substrate connection, to multi-layer structure to ensure stable performance, each link cooperates with each other. The vertical blue light high-efficiency color conversion structure enables the color conversion structure to fully convert blue light into other colors of light, reducing light transmission loss, and achieving higher brightness while using smaller LEDs, greatly improving display performance and providing strong support for the miniaturization and high performance of display products.

[0017] 2. The present invention uses a color conversion structure in the display structure to realize the red light structure, abandoning the traditional AlGaInP red light. The characteristics of the quantum dot material enable it to perform well in red light conversion, effectively improving the light efficiency and reducing energy waste. At the same time, it avoids the use of relatively complex and high-cost AlGaInP materials, significantly reducing production costs, and providing display products with more competitive prices while ensuring quality, thereby promoting the development of the display industry towards high efficiency and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0019] Among them, 1. Bottom layer; 2. Encapsulation layer 1; 3. Conductive block; 4. LED crystal; 5. Wrapping layer; 6. Contact layer; 7. Flat layer; 8. Light blocking block; 9. Color conversion layer; 10. Encapsulation layer 2; 11. Filter 1; 12. Filter 2; 13. Encapsulation layer 3. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the present specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0021] Please see the attached Figure 1An embodiment of the present invention provides a MicroLED packaging structure containing a color conversion layer, including a bottom layer 1 and multiple LED crystals 4. A packaging layer 2 is provided on the top of the bottom layer 1, and multiple conductive blocks 3 are provided inside the packaging layer 2. The MicroLED is welded to the conductive blocks 3 by AuSn eutectic welding, AuIn eutectic welding, ACF welding, etc. Taking AuSn eutectic welding as an example, it uses gold-tin alloy (20% tin) to be liquid at temperatures above 280°C. When the temperature slowly drops, a eutectic reaction occurs, forming a good connection, thereby achieving a stable electrical connection between the MicroLED and the conductive block 3. One side of the LED crystal 4 is fixedly connected to the outside of the conductive block 3. The conductive block 3 is made of copper, which has good conductivity and can provide stable current input for the LED crystal 4 to meet the working requirements of the LED crystal 4. The LED crystal 4 is a composite material including metal, ITO, p+-GaN, MQW, n+-GaN and u-GaN.After soldering is completed, the u-GaN and n+-GaN parts in the LED crystal 4 need to be thinned. Thinning the wafer has many benefits. The thinned chip is smaller and can adapt to thinner packaging designs. It also has a shorter heat diffusion path and a higher surface area to volume ratio, which helps to transfer the heat generated by the chip during operation faster and more efficiently. If the chip is too thick, heat will accumulate inside the chip during the transfer process, causing local overheating and affecting device performance. Then, a wrapping layer 5 is set outside the packaging layer 2 and the LED crystal 4. The material of the wrapping layer 5 is SiO or SiN, or a stacked structure of the two. This layer mainly plays the role of protecting the LED crystal 4 , to prevent it from being affected by external environmental factors, a contact layer 6 is provided on the outside of the wrapping layer 5, and the contact layer 6 is used to make ohmic contact on the outside of the wrapping layer 5. The material of the contact layer 6 is ITO, which has good conductivity and optical transparency. It can achieve ohmic contact while minimizing the impact on light propagation, ensuring that subsequent light can be smoothly emitted. A flat layer 7 is provided on the outside of the wrapping layer 5 and the contact layer 6. The material of the flat layer 7 is PI, OC and other materials, which has good insulation performance, can effectively isolate the circuit, prevent the occurrence of problems such as short circuits, and provide a flat foundation for subsequent structures to protect the circuit structure. A color conversion layer 9 is provided on the outside of the flat layer 7. A plurality of light-blocking blocks 8 are installed inside the conversion layer 9, and one end of the light-blocking block 8 is in contact with the outer side of the flat layer 7. The light-blocking block 8 is a black photoresist, and its main function is to absorb and block light to prevent light crosstalk between different pixel units, thereby improving the contrast and color purity of the display, making the display clearer and the color more vivid. The other end of the light-blocking block 8 and the outer side of the color conversion layer 9 are provided with an encapsulation layer 2 10, which is encapsulated with the encapsulation layer 2 10. The material of the encapsulation layer 2 10 is a composite material of silicon nitride and aluminum oxide. This composite material has good chemical stability, corrosion resistance and light transmittance, and can prevent water vapor and oxygen from eroding the internal structure, further protecting the internal LED crystal 4, the interface The touch layer 6 and other structures are not damaged by the external environment, which extends the service life of the entire packaging structure. The outside of the packaging layer 2 10 is provided with a filter 11 and a filter 2 12. The colors of the filter 11 and the filter 2 12 are different. Their function is to shield the blue light that is not completely converted. By selectively filtering the light, the final emitted light is more in line with the display requirements in color and spectrum, and the display effect is optimized. The outside of the packaging layer 2 10, the filter 1 11 and the filter 2 12 is provided with a packaging layer 3 13, and finally covered with the packaging layer 3 13. The material of the packaging layer 3 13 is also a composite material of silicon nitride and aluminum oxide, which further strengthens the protection of the internal structure and blocks the interference of external adverse factors.At this point, the overall structural packaging operation is completed. Through this vertical blue light color conversion layer structure solution, a smaller LED can achieve a higher brightness effect. It has significant advantages in the display field and is expected to promote the development of related display products towards higher performance.

[0022] Please see the attached Figure 1 The present invention also provides a method for packaging a MicroLED including a color conversion layer, including the following steps: S1. Remove the used MicroLED from the sapphire using laser lift-off technology; S2. Solder the MicroLED to the conductive block 3 by AuSn eutectic welding, AuIn eutectic welding, or ACF welding. S4, thinning the u-GaN and n+-GaN parts in the LED crystal 4 and wrapping them with a PV wrapping layer 5; S5, making ohmic contact with the outside of the wrapping layer 5 using the contact layer 6, and then covering with the flat layer 7 to protect the circuit structure; S6. A light blocking block 8 is provided outside the flat layer 7 to absorb and block light; S7, placing a color conversion layer 9 outside the light blocking block 8, the color conversion layer 9 being a quantum dot material or a phosphor material, and then encapsulating it with an encapsulation layer 10; S8. Set filter 11 and filter 2 12 outside the second encapsulation layer 10 to shield the blue light that is not completely converted, and then cover it with the third encapsulation layer 13 to complete the encapsulation operation of the entire structure.

[0023] Specifically, first, the used MicroLED is peeled off from the sapphire through laser lift-off technology. Since MicroLED chips based on GaN luminescent materials often use sapphire as the mainstream substrate for epitaxial growth, this is because the lattice mismatch between GaN and sapphire is low and sapphire is cheap. However, the sapphire substrate has problems such as non-conductivity and poor thermal conductivity. These problems seriously affect the luminous efficiency of MicroLED devices and are not conducive to their application in flexible displays. Laser lift-off technology uses a short-wavelength laser with photon energy greater than the energy band gap of gallium nitride (GaN) but less than the band gap of sapphire and aluminum nitride (AlN). It irradiates from one side of the sapphire. After the laser passes through sapphire and AlN, it is absorbed by the surface GaN, which undergoes thermal decomposition to generate nitrogen and metallic gallium. The nitrogen escapes, and then the GaN epitaxial layer and the sapphire substrate can be separated by mechanical force. This step lays the foundation for the subsequent reasonable installation of MicroLEDs and the optimization of their performance. Subsequently, the MicroLED is welded to the conductive block 3 through AuSn eutectic welding, AuIn eutectic welding, ACF welding, etc., and a eutectic reaction occurs, thereby forming a stable and reliable connection, achieving a good electrical connection between the MicroLED and the conductive block 3, ensuring that the conductive block 3 can stably provide current to the MicroLED and guarantee the power supply required for the normal operation of the LED crystal 4. Then, the u-GaN in the LED crystal 4 is removed.The n+-GaN part is thinned, and the chip after thinning is smaller. The thinned chip has a shorter heat diffusion path and a higher surface area to volume ratio, which helps to transfer the heat generated by the chip during operation faster and more effectively. It is then wrapped with a PV wrapping layer 5 to protect the LED crystal 4. It can prevent the LED crystal 4 from being affected by external environmental factors. The contact layer 6 is used to make ohmic contact on the outside of the wrapping layer 5. The ohmic contact can ensure that the current is smoothly transmitted between the wrapping layer 5 and the subsequent structure. At the same time, its good optical transparency can minimize the impact on light propagation while achieving ohmic contact, ensuring that subsequent light can be emitted smoothly. The flat layer 7 is then covered to protect the circuit structure. The material of the flat layer 7 has good insulation properties and can effectively isolate the circuit to prevent problems such as short circuits. A light blocking block 8 is set outside the flat layer 7 to absorb and block light. The light blocking block 8 is a black photoresist. Its main function is to prevent light crosstalk between different pixel units. During the display process, if light crosstalk occurs between different pixel units, the contrast of the displayed image will be reduced, the color purity will be reduced, and the image will become blurred. The presence of the light blocking block 8 can effectively absorb and block these crosstalk lights, thereby improving the contrast and color purity of the display, making the displayed image clearer and the colors more vivid, and greatly improving the display effect. , then encapsulate it with the second encapsulation layer 10. The material of the second encapsulation layer 10 is a composite material of silicon nitride and aluminum oxide. This composite material has good chemical stability, corrosion resistance and light transmittance. The second encapsulation layer 10 can prevent the erosion of the internal structure by external adverse factors such as water vapor and oxygen, and further protect the internal LED crystal 4, contact layer 6 and other structures from damage by the external environment, thereby extending the service life of the entire encapsulation structure and ensuring its long-term stable operation. Filters 11 and 2 are set on the outside of the second encapsulation layer 10 to shield the blue light that is not completely converted. Finally, it is covered with the third encapsulation layer 13. The material of the third encapsulation layer 13 is also a composite material of silicon nitride and aluminum oxide. The composite material further strengthens the protection of the internal structure and blocks interference from adverse external factors. Through the above series of operations, the overall structural packaging operation is completed. Finally, through the vertical blue light + color conversion structure solution, a smaller LED can achieve higher brightness. In this solution, the vertical blue light structure can more efficiently excite the color conversion layer 9, allowing the quantum dots to more fully convert blue light into other desired colors. At the same time, due to the optimized structural design, light loss during transmission is reduced, thus achieving higher brightness even when using smaller LEDs. This has significant advantages in the display field and is expected to promote the development of related display products towards higher performance.

[0024] Working principle: First, the used MicroLED is peeled off from the sapphire through laser lift-off technology, and the MicroLED is welded to the conductive block 3 through AuSn eutectic welding, AuIn eutectic welding, ACF welding, etc., and then the u-GaN, n+-GaN parts in the LED crystal 4 are thinned, and then wrapped with a PV wrapping layer 5, and ohmic contact is made with a contact layer 6 on the outside of the wrapping layer 5, and then covered with a flat layer 7 to protect the circuit structure. A light blocking block 8 is set on the outside of the flat layer 7 to absorb and block light, and then packaged with the packaging layer 2 10, and a filter 11 and a filter 2 12 are set on the outside of the packaging layer 2 10 to shield the blue light that is not completely converted, and then covered with the packaging layer 3 13, that is, the overall structure packaging operation is completed, and the vertical blue light + color conversion structure scheme is used to achieve a smaller LED and a higher brightness effect.

[0025] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A MicroLED packaging structure containing a color conversion layer, comprising a bottom layer (1) and a plurality of LED crystals (4), characterized in that: A packaging layer (2) is provided on the top of the bottom layer (1), a plurality of conductive blocks (3) are provided inside the packaging layer (2), one side of the LED crystal (4) is fixedly connected to the outside of the conductive block (3), a wrapping layer (5) is provided outside the packaging layer (2) and the LED crystal (4), a contact layer (6) is provided outside the wrapping layer (5), a flat layer (7) is provided outside the wrapping layer (5) and the contact layer (6), and a color layer (7) is provided outside the flat layer (7). A conversion layer (9), wherein a plurality of light-blocking blocks (8) are installed inside the color conversion layer (9), and one end of the light-blocking block (8) is bonded to the outer side of the flat layer (7), and an encapsulation layer 2 (10) is provided between the light-blocking block (8) and the other end and the outer side of the color conversion layer (9), and an optical filter 1 (11) and an optical filter 2 (12) are provided on the outer side of the encapsulation layer 2 (10), and an encapsulation layer 3 (13) is provided on the outer side of the encapsulation layer 2 (10), the optical filter 1 (11) and the optical filter 2 (12).

2. The MicroLED package structure with a color conversion layer according to claim 1, wherein: The conductive block (3) is made of copper and is used to provide current to the LED crystal (4).

3. The MicroLED package structure with a color conversion layer according to claim 1, wherein: The LED crystal (4) is a composite material, comprising metal, ITO, p+-GaN, MQW, n+-GaN and u-GaN.

4. The MicroLED package structure with a color conversion layer according to claim 1, wherein: The material of the wrapping layer (5) is SiO or SiN, or a laminated structure of the two.

5. The MicroLED package structure with a color conversion layer according to claim 1, wherein: The contact layer (6) is used for ohmic contact, and the material of the contact layer (6) is ITO.

6. The MicroLED package structure with a color conversion layer according to claim 1, wherein: The material of the flat layer (7) is organic matter and is used for flatness and insulation.

7. The MicroLED package structure with a color conversion layer according to claim 1, wherein: The light blocking block (8) is black photoresist and is used to absorb and block light.

8. The MicroLED package structure with a color conversion layer according to claim 1, wherein: The materials of the encapsulation layer 1 (2), the encapsulation layer 2 (10) and the encapsulation layer 3 (13) are all silicon nitride, aluminum oxide or their composite materials, and are used to prevent water vapor and oxygen from corroding other structures.

9. The MicroLED package structure with a color conversion layer according to claim 1, wherein: The color of the filter 1 (11) and the color filter 2 (12) are different, and are used to shield the blue light that is not completely converted.

10. A method for packaging a MicroLED with a color conversion layer, applied to a MicroLED packaging structure with a color conversion layer according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Remove the used MicroLED from the sapphire using laser lift-off technology; S2, soldering the MicroLED to the conductive block (3) by AuSn eutectic soldering, AuIn eutectic soldering, or ACF soldering; S4, thinning the u-GaN and n+-GaN portions of the LED crystal (4) and wrapping them with a PV wrapping layer (5); S5, digging a hole outside the wrapping layer (5) to make an ohmic contact with the contact layer (6), and then covering it with a flat layer (7) to protect the circuit structure; S6. Setting a light blocking block (8) outside the flat layer (7) to absorb and block light; S7, placing a color conversion layer (9) outside the light blocking block (8), the color conversion layer (9) being a quantum dot material or a phosphor material, and then encapsulating it with an encapsulation layer 2 (10); S8. Set filter 1 (11) and filter 2 (12) outside the packaging layer 2 (10) to shield the blue light that is not completely converted, and then cover it with packaging layer 3 (13), thus completing the packaging operation of the entire structure.

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