Micro LED chip packaging structure and preparation method

Abstract

The present invention relates to the field of microelectronics and discloses a micro-LED chip packaging structure and preparation method. The method comprises the following steps: first, sequentially growing an N-type base layer, a quantum well, and a P-type base layer on a sapphire substrate; then, using laser lift-off technology, lift-off the micro-LED chip from the sapphire substrate and transferring it to a temporary substrate; then, sequentially bonding the multiple temporary substrates to a transparent substrate using a transparent bonding adhesive; and finally, using a planarization process to fill the gaps between the micro-LED chip and the transparent substrate to ensure a smooth surface. The laser lift-off technology and precise bonding process ensure the integrity of the micro-LED chip, avoiding damage associated with traditional methods. The use of a transparent bonding adhesive increases light transmittance, improving the brightness and clarity of the display. The triangular arrangement solves the visual color deviation problem associated with the existing "straight" arrangement, thereby improving the uniformity of display quality.

Description

Technical Field

[0001] The present invention relates to the field of microelectronics technology, and in particular to a micro LED chip packaging structure and a preparation method thereof. Background Art

[0002] As an emerging display technology, micro-LED technology is widely used in high-resolution, low-power, and long-life displays. Micro-LED chip packaging is a critical process step in achieving efficient displays. Currently, most micro-LED chip packaging technologies use mechanical stripping. While simple, this method can easily cause physical damage to the chip, affecting its yield rate. Cracks and defects on the chip surface are common, especially in mass production. Furthermore, mechanical stripping makes it difficult to precisely control the docking position between the micro-LED chip and the substrate, which poses a risk to the chip's stability and electrical connectivity during the subsequent packaging process.

[0003] During the packaging process, the planarization step of the filler material typically relies on manual operation or simple coating techniques, resulting in uneven filling and uneven chip surfaces. This in turn affects the quality of the electrical connection and causes subsequent display instability. The bonding adhesive materials used in traditional packaging significantly affect light transmittance. Existing materials often absorb or scatter light, especially when demanding high-resolution and high-brightness displays, reducing display brightness and clarity.

[0004] Traditional micro-LED chips are often arranged in a straight line. While this layout ensures color consistency from the front and left and right angles, it often exhibits color shift from vertical to horizontal, impacting display uniformity and visual quality. As display technology continues to demand more consistent color, existing arrangements are unable to effectively address color differences at different viewing angles, making them difficult to meet the demands of modern high-end display products.

[0005] Therefore, improving the micro-LED chip packaging process, optimizing the chip arrangement, and selecting suitable packaging materials to improve display effects and stability have become important directions for the current development of micro-LED technology. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention provides a micro-LED chip packaging structure and preparation method to solve the problems of chip damage, unstable electrical connection, low light transmittance and color deviation in the micro-LED chip packaging process in the existing technology.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions: a micro LED chip packaging structure, comprising at least three micro LED chips, wherein the micro LED chips are arranged in a triangle shape;

[0008] Each micro-LED chip includes an N-type base layer, a quantum well layer and a P-type base layer, and electrodes are in contact with the N-type base layer and the P-type base layer respectively, and the electrodes include a positive electrode in contact with the P-type base layer and a negative electrode in contact with the N-type base layer;

[0009] The space between the micro-LED chip and the transparent substrate is filled with BCB, PI or PDMS material;

[0010] A metal pad is provided in the central area of ​​the three micro LED chips. The diameter of the metal pad is greater than 30 microns, and the distance between the metal pad and the metal ring is greater than 5 microns.

[0011] Preferably, the size of the micro LED chip ranges from 1 micron×1 micron to 400 microns×400 microns.

[0012] Preferably, the transparent substrate is made of sapphire, glass or quartz, and has a thickness of 0.5 mm to 1 mm.

[0013] Preferably, the material used for the N-type base layer and the P-type base layer is one of gallium nitride and aluminum gallium indium phosphide.

[0014] Preferably, the filling material between the micro LED chip and the transparent substrate is transparent polyimide, polydimethylsiloxane or benzocyclobutene.

[0015] Preferably, the packaging structure further includes a pad provided on the chip electrode, the size of the pad is greater than 60 microns×60 microns, and the material of the pad is gold, tin or aluminum.

[0016] A method for preparing a micro LED chip comprises the following steps:

[0017] S1. Growing an N-type GaN layer, a quantum well layer, and a P-type GaN layer sequentially on a sapphire substrate, or growing an N-type AlGaInP layer, a quantum well layer, and a P-type AlGaInP layer on a GaAs substrate;

[0018] S21. A positive electrode is deposited on the P-type base, and a negative electrode is deposited on the N-type base, wherein the electrode material is chromium, aluminum, titanium and gold;

[0019] S3. Control the size of the micro-LED chip to be 1 micron × 1 micron to 400 microns × 400 microns;

[0020] S4. Peel the micro-LED chip from the sapphire substrate to a temporary substrate using laser technology with a laser power of 50mW to 250mW.

[0021] Preferably, the size of the sapphire substrate is four inches or six inches, and the angle between the edge of the micro LED chip and the flat edge of the substrate is 45°±5°.

[0022] Preferably, the micro LED chip is peeled from the sapphire substrate to the temporary substrate by laser lift-off technology, and the lift-off power is 50mW to 250mW.

[0023] Preferably, the electrodes of the micro-LED chip are made of chromium, aluminum, titanium and gold materials, and the thickness of the metal layer matches the current demand.

[0024] The present invention provides a micro-LED chip packaging structure and preparation method. It has the following beneficial effects:

[0025] 1. This invention utilizes laser lift-off technology combined with a precise butt-jointed bonding process to effectively peel the micro-LED chip from the sapphire substrate and transfer it to a temporary baseplate, while maintaining the chip's integrity. This technical solution avoids damage to the micro-LED chip during the lift-off process, a problem inherent in conventional methods. It also addresses the potential for chip cracking or surface damage caused by mechanical lift-off in existing technologies, improving both the yield and quality of micro-LED chips.

[0026] 2. This invention ensures the smoothness of the micro-LED chip surface through a precisely controlled fill material planarization step, avoiding poor electrical connections caused by surface unevenness. Compared to traditional manual filling methods, this technology provides higher precision and stability during the planarization process, effectively preventing package failures caused by surface unevenness, thereby improving the reliability and service life of the display device.

[0027] 3. This invention utilizes transparent bonding adhesives, such as BCB, PI, and PDMS, during chip packaging to optimize the optical performance of micro-LED chips. This technical solution effectively increases light transmittance and solves the light absorption and scattering issues of some packaging materials in existing technologies, thereby enhancing the brightness and clarity of the display, making it particularly suitable for high-brightness and high-resolution display applications.

[0028] 4. This invention provides a triangular arrangement of micro-LED chips, resolving the color deviation problem caused by the traditional straight-line arrangement. This innovative arrangement not only optimizes the RGB color mixing effect but also enhances color consistency across different viewing angles, resolving the color difference problem caused by improper arrangement in existing technologies and further improving display quality and viewing experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a planar schematic diagram of the micro LED chip packaging structure of the present invention;

[0030] Figure 2 This is a schematic cross-sectional view of the micro-LED chip packaging structure of the present invention. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the specification of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0032] Please see the attached Figure 1 An embodiment of the present invention provides a micro-LED chip package structure comprising at least three micro-LED chips arranged in a triangular pattern. This triangular arrangement significantly improves display quality and reduces color shift. Through a rational layout and optimized electrical connections, the micro-LED chips achieve good contact with the substrate via appropriate filler material, and are further protected by metal pads to prevent damage during the packaging process.

[0033] In this embodiment, the micro-LED chips are arranged in a triangular pattern. The key to this arrangement is that the three RGB micro-LED chips (red, green, and blue) are arranged in an equilateral triangle, resulting in more uniform light mixing between the three chips. This design helps maintain color consistency across different viewing angles, particularly when viewed from above or below, effectively reducing color shift.

[0034] Specifically, the triangular arrangement of the micro-LED chips ensures that the red, green, and blue chips are located at the vertices of the triangle, optimizing the mixing effect of the three colors of light. Due to the advantages of the triangular layout, the three colors of light will not show obvious deviation at different viewing angles, which is particularly important for large-scale displays and high-resolution displays.

[0035] As an option, the size of micro-LED chips is typically set to range from 1 micron x 1 micron to 400 microns x 400 microns. The size of micro-LED chips can be adjusted appropriately based on actual needs. Specifically, for high-resolution displays, the size of micro-LED chips can be smaller to achieve higher pixel density; for low-resolution displays, larger sizes can be selected.

[0036] The choice of a transparent substrate is also crucial in this invention. It ensures unimpeded light output from the micro-LED chip. Typically, transparent substrates are made of sapphire, glass, or quartz. In some embodiments, the thickness of the transparent substrate is typically set between 0.5 mm and 1 mm. The selected substrate material must possess good mechanical strength and optical transparency to ensure stable and clear display effects.

[0037] The materials used for N-type base layer and P-type base layer are gallium nitride as an example. Figure 2 ,Each micro-LED chip includes N-type gallium nitride, quantum well layer and P-type gallium nitride layer, and the electrodes are in contact with the N-type gallium nitride layer and the P-type gallium nitride layer respectively;

[0038] Micro-LED chips are typically made of gallium nitride (GaN) material, with a structure consisting of N-type GaN, quantum well layers, and P-type GaN layers. This structure is grown sequentially on a sapphire substrate using MOCVD (metal-organic chemical vapor deposition) technology.

[0039] N-type gallium nitride layer: This layer plays the role of electron transport and provides load current.

[0040] Quantum well layer: As the light-emitting layer, the thickness and doping concentration of the quantum well have a direct impact on the light emission efficiency.

[0041] P-type gallium nitride layer: This layer is responsible for accepting positive current from the power supply, thereby driving the light-emitting process.

[0042] Through standard semiconductor processing, the P-type GaN layer is connected to the positive electrode, and the N-type GaN layer is connected to the negative electrode. Electrode materials can be made of metals such as chromium, aluminum, titanium, and gold, which have good electrical conductivity and can effectively prevent oxidation.

[0043] The size of micro-LED chips usually ranges from 1 micron x 1 micron to 400 microns x 400 microns, and the specific size depends on the resolution requirements of the display. For high-resolution displays, the size of micro-LED chips will be smaller.

[0044] The space between the micro-LED chip and the transparent substrate is filled with BCB, PI, or PDMS. In the packaging structure of the present invention, the connection between the micro-LED chip and the transparent substrate is made of a filler material. Examples of filler materials include BCB (benzocyclobutene), PI (polyimide), and PDMS (polydimethylsiloxane). These fillers offer excellent transparency and stability, ensuring a secure connection between the micro-LED chip and the substrate.

[0045] Specifically, the filler material is used to fill the gap between the micro-LED chip and the substrate, ensuring that the micro-LED chip does not shift or displace due to external forces during the packaging process. The thickness of the filler material is typically controlled to be within 5 microns of the height of the micro-LED chip electrodes. If the filler material thickness exceeds the electrode height, the excess filler material can be removed through processes such as photolithography, dry etching, wet etching, or laser ablation to ensure that the micro-LED chip electrodes are exposed and achieve good electrical contact.

[0046] A metal pad is placed in the center of each of the three micro-LED chips. The diameter of the metal pad is greater than 30 microns, and the spacing between the metal pad and the metal ring is greater than 5 microns. In this embodiment, the micro-LED chip packaging structure further includes a metal pad placed in the center of the chip. The diameter of the metal pad is typically greater than 30 microns, and the spacing between the metal pad and the metal ring is typically greater than 5 microns. The primary function of the metal pad is to prevent physical damage to the chip from contact with ejector pins during the packaging process. The metal pad has strong mechanical strength and effectively distributes pressure from the ejector pins, preventing damage to the chip surface.

[0047] In a specific embodiment, the material of the metal pad can be selected from metals with strong mechanical strength such as aluminum, chromium, and gold. These metal materials can not only enhance the chip's damage resistance, but also provide additional protection for the chip during the packaging process, ensuring that no electrode damage or cracks will occur in subsequent patch operations.

[0048] In some embodiments, the electrical connection of the micro-LED chip is achieved through a metal layer. The metal materials used include chromium, aluminum, titanium, copper, etc. The design of the metal layer must not only consider electrical performance, but also ensure that it can firmly contact with the micro-LED chip electrodes during the packaging process, thereby ensuring long-term stable electrical connection.

[0049] The electrode size is typically greater than 60 microns by 60 microns. The pads are typically made of gold, tin, or aluminum, which have excellent weldability and ensure a good connection to the external circuit during subsequent soldering. Furthermore, the design of the metal layer and pads should meet the current requirements of the micro-LED chip to ensure stable current transmission.

[0050] In some embodiments, in order to accurately control the arrangement and size of the micro LED chip, the following formula can be used for calculation and design. Assume that the size of the micro LED chip is ,in is the width of the chip, is the height of the chip. According to the requirements of the triangle arrangement, the minimum spacing between chips It can be calculated by the following formula:

[0051]

[0052] in, and are the width and height of the chip respectively. Based on this formula, the minimum distance between chips can be calculated to ensure a compact arrangement without overlapping.

[0053] At the same time, the design of the metal pad also needs to meet the following conditions: the diameter of the metal pad Should be greater than 30 microns, and the minimum spacing between the metal pad and the metal ring Should be greater than 5 microns. The formula is as follows:

[0054]

[0055] The design of these parameters can ensure the effective function of the metal pad and prevent the chip from being damaged by external pressure.

[0056] The micro-LED chip package structure proposed in this embodiment successfully addresses numerous issues with traditional packaging, such as color consistency, chip damage, and excessive package size, through a series of innovative solutions, including a triangular arrangement, metal pad design, and filler materials. Furthermore, through rational electrical connections and precise design calculations, the package structure's stability and long-term reliability are ensured. This structure is widely applicable to various display devices, particularly high-resolution, high-brightness, and high-reliability micro-LED displays.

[0057] As part of this application, the present invention also provides a method for fabricating a micro-LED chip, aiming to produce a micro-LED chip with precise dimensions and stable performance. This method includes multiple steps, covering key processes such as micro-LED chip growth, chip electrode formation, and final peeling and transfer. Through these process steps, the structural quality, electrical performance, and connection to the substrate of the micro-LED chip can be effectively controlled, thereby meeting the requirements of high resolution, long life, and high brightness display.

[0058] In this embodiment, the fabrication method for the micro-LED chip begins with a sapphire substrate. A gallium nitride (GaN) layer, a quantum well layer, and a p-type GaN layer are sequentially grown using semiconductor processes. Electrodes are then formed through photolithography and metal deposition. Finally, the micro-LED chip is peeled from the sapphire substrate and transferred to a temporary substrate. The key to this entire process lies in precise control of each step to ensure high-quality micro-LED chip dimensions, structure, and electrical performance. The micro-LED chip is peeled from the sapphire substrate using laser lift-off technology. During the lift-off process, a laser power of 50mW to 250mW is used to ensure the integrity of the micro-LED chip. The number of chips peeled at each lift-off is controlled as 1 / (M*N), where M and N are natural numbers greater than or equal to 2, to avoid damage caused by peeling too many chips at once.

[0059] In this embodiment, the micro-LED chip is grown on a sapphire substrate. First, an N-type gallium nitride layer, a quantum well layer, and a P-type gallium nitride layer are sequentially grown on the sapphire substrate using MOCVD (metal organic chemical vapor deposition) technology. Specifically:

[0060] N-type gallium nitride layer: This layer is responsible for providing electron carriers and is usually composed of highly doped gallium nitride for electron transmission.

[0061] Quantum well layer: Located between the N-type and P-type gallium nitride layers, it serves as the light-emitting layer. This layer enhances light emission efficiency through quantum effects. The thickness and doping concentration of the quantum well layer have a significant impact on the optoelectronic performance of LEDs.

[0062] P-type gallium nitride layer: This layer is responsible for receiving positive current, promoting the recombination of electrons and holes, and thus stimulating the generation of light.

[0063] In some embodiments, the thickness of the N-type GaN layer is typically several microns, the quantum well layer is several nanometers, and the thickness of the P-type GaN layer varies depending on the application. The doping concentration also needs to be adjusted based on specific requirements to ensure good optoelectronic performance.

[0064] After the gallium nitride and quantum well layers are grown, the next step is to form electrodes for the micro-LED chip. In this embodiment, metal electrodes are deposited on the P-type gallium nitride layer and the N-type gallium nitride layer using photolithography:

[0065] P-type electrode: A metal electrode is deposited on the P-type gallium nitride layer. Metals such as aluminum, titanium, or gold are usually selected. The size and shape of the electrode should be designed according to the size of the micro-LED chip.

[0066] N-type electrode: A metal electrode is deposited on the N-type GaN layer. The electrode material can be selected from chromium, titanium or aluminum to ensure good contact between the electrode and the N-type GaN layer.

[0067] Through photolithography, the electrode pattern is precisely transferred to the surface of the GaN layer, ensuring that the electrode covers and maintains good contact with the GaN layer. In some embodiments, the thickness of the electrode material typically ranges from tens to hundreds of nanometers, with the specific thickness being selected based on current requirements and performance requirements.

[0068] The size of the micro-LED chip is typically determined by the resolution of the display. In this embodiment, the size of the micro-LED chip can range from 1 micron x 1 micron to 400 microns x 400 microns, depending on the application requirements. For example, in high-resolution displays, the size of the micro-LED chip is typically smaller to achieve a higher pixel density.

[0069] Through precise photolithography, the size of each micro-LED chip can be controlled. The width of the chip and height It can be calculated by the following formula:

[0070]

[0071] in, Indicates the width of the chip, Indicates the height of the chip. The size of the micro-LED chip can be flexibly adjusted according to the display resolution requirements. Generally, as the display resolution increases, the size of the micro-LED chip will decrease to accommodate more pixels.

[0072] Laser lift-off is used to separate the micro-LED chip from the sapphire substrate. In this process, a laser beam with an appropriate wavelength and power is used to lift the micro-LED chip from the sapphire substrate. The laser power is typically set between 50mW and 150mW.

[0073] Through the laser lift-off process, the micro-LED chip is separated from the sapphire substrate and transferred to a temporary substrate. The temporary substrate is usually made of flexible materials such as benzocyclobutene (BCB), polyimide (PI) or polydimethylsiloxane (PDMS). These materials can effectively protect the micro-LED chip and prevent it from being damaged by external forces during the transfer process.

[0074] In some embodiments, laser lift-off is performed by:

[0075]

[0076] By adjusting these parameters, the stability of the peeling process and the integrity of the micro-LED chip can be ensured.

[0077] After laser lift-off, the micro-LED chips are transferred to a temporary substrate. The three temporary substrates are sequentially bonded to a transparent substrate, with the flat edges aligned. The use of the temporary substrates is crucial during the transfer of the micro-LED chips. They require both good mechanical strength and flexibility to accommodate subsequent processing steps.

[0078] After transfer, the micro-LED chip will enter the subsequent packaging and electrical connection steps. Generally speaking, after the micro-LED chip is transferred to the temporary substrate, its size, structure and electrical performance need to undergo a series of tests and adjustments to ensure that it meets the requirements of the final display device.

[0079] The fabrication method for the micro-LED chip in this embodiment successfully produces a micro-LED chip with stable performance and precise dimensions through rational material selection, precise process control, laser lift-off, and transfer steps. This method not only meets the requirements of high-resolution display screens but also ensures high performance of the micro-LED chip in subsequent packaging and applications.

[0080] Through the implementation of the above technical solutions, the damage rate in the chip manufacturing process can be effectively reduced, while the optoelectronic performance of the chip can be improved, providing a stable and efficient technical path for the manufacture of micro-LED display devices.

[0081] As part of this application, the present invention also provides a method for preparing a micro-LED chip packaging structure. This method aims to address issues such as chip damage and color shift during the prior art packaging process, ensuring consistent display of the micro-LED chip at different viewing angles and improving package stability. This method ensures efficient chip packaging by improving various aspects of the packaging structure, including the arrangement of the micro-LED chips, the filling process, substrate bonding, and electrical connections. In particular, the triangular arrangement of the micro-LED chips effectively reduces the risk of ejector pin damage while improving display quality.

[0082] In this embodiment, the fabrication method for the micro-LED chip package structure is achieved through several key steps, including chip electrical connection, temporary substrate bonding, filling, metal pad design, and final cutting. Precise control of each step is crucial to the final package quality and chip display performance.

[0083] In this embodiment, the micro-LED chips are first electrically connected to each other through electrical connections. The electrical connection material used is a metal layer. Common metal materials include chromium, aluminum, and titanium. Depending on the needs, the thickness of the metal layer is typically between tens and hundreds of nanometers. The electrical connection process can be accomplished through metal evaporation or sputtering techniques.

[0084] Generally, the metal layer needs to be in good contact with the electrodes of the micro-LED chip to ensure smooth current transmission. In some embodiments, the thickness of the metal layer is directly related to the current demand and stability requirements, and therefore needs to be determined according to the specific application.

[0085] Formula part: For the design of electrical connection, the thickness of the required metal layer It can be determined by the following formula:

[0086]

[0087] in, is the maximum current, is the electrical conductivity of the metal, is the cross-sectional area of ​​the metal layer through which current flows. This formula ensures that the design of the metal layer meets the current carrying requirements and ensures the stability of the electrical connection.

[0088] After the electrical connection of the micro-LED chip is completed, the next step is to connect the micro-LED chip to the transparent substrate. This process requires a bonding process. In this embodiment, the bonding material used is transparent polyimide (PI), polydimethylsiloxane (PDMS), or benzocyclobutene (BCB). These materials have good transparency and mechanical strength, ensuring a stable bond between the micro-LED chip and the substrate.

[0089] Specifically, the bonding process between the transparent substrate and the temporary substrate utilizes hot pressing, typically at a temperature of 150°C to 250°C for a duration between 30 seconds and 1 minute. This controlled temperature and duration ensures the fluidity and adhesion of the bonding material, preventing delamination or instability during subsequent processing.

[0090] In one possible implementation, the temporary substrate can be made of a flexible material, such as PDMS, which effectively protects the micro-LED chips from damage during subsequent operations. Furthermore, aligning the substrate's flat edges ensures accurate positioning of multiple micro-LED chips on the substrate.

[0091] Because the micro-LED chip itself is a protruding structure, to ensure the flatness of the entire package structure, it needs to be filled with one or more stacked structures of organic, metal, or inorganic materials. The key to this process is to use the right filling material to fill the gap between the micro-LED chip and the transparent substrate, and to ensure that the thickness of the filling layer is consistent with the height of the chip electrodes.

[0092] In some embodiments, organic fillers include BCB, PI, PDMS, epoxy resin, silicone, or acrylic (polymethyl methacrylate), metals include chromium (Cr) and aluminum (Al), and inorganic fillers include silicon oxide, aluminum oxide, titanium oxide, and silicon nitride. These fillers have excellent mechanical strength and transparency, effectively ensuring that the electrodes of the micro-LED chip are exposed without affecting light transmission. Each filler can also be supplemented with appropriate carbon powder based on the required light transmittance.

[0093] The thickness of the filling layer is typically controlled to be within 5 microns of the micro-LED chip electrode height. If the filling layer thickness exceeds the height of the micro-LED electrode, the excess filling material must be removed through subsequent processes such as photolithography, dry etching, wet etching, or laser ablation to ensure the exposed portion of the electrode for good electrical contact.

[0094] In one embodiment, the thickness of the filling material Height to chip electrode The relationship between can be expressed as:

[0095]

[0096] This control ensures the integrity of the chip electrodes and prevents the accumulation of filler material that could affect the chip's electrical connections. The electrodes on the micro-LED chip are electrically connected through a metal layer. The electrodes can be composed of a single metal or a stack of multiple metals. Metal types include chromium, aluminum, titanium, platinum, gold, copper, and tin. The substrate is then thinned and cut into individual devices.

[0097] In this embodiment, the packaging structure for the micro-LED chip also includes a metal pad in the center of the chip. The metal pad's diameter is typically greater than 30 microns, and the minimum spacing between the metal pad and the metal ring is at least 5 microns. The metal pad is designed to prevent the pressure from the ejector pins during the packaging process from directly impacting the micro-LED chip and potentially damaging its surface. The metal pad effectively dissipates the pressure from the ejector pins, protecting the micro-LED chip from physical damage.

[0098] Specifically, the metal pad can be made of aluminum, chromium, gold and other metals, which have strong mechanical strength and can maintain stability during the packaging process. The design of the metal pad can not only increase the compressive strength of the chip, but also ensure that the ejector pin will not damage the micro-LED chip during operation.

[0099] Formula part: Assume that the diameter of the metal pad is , the distance between the metal ring is , then:

[0100]

[0101] With this design, the metal pad can effectively prevent damage from the ejector pin while maintaining good electrical contact performance.

[0102] During the packaging process, the micro-LED chip undergoes the aforementioned electrical connection, bonding, and filling processes before it is finally cut. This process typically uses laser cutting or mechanical cutting to separate the micro-LED chip from the substrate, forming an independent micro-LED device.

[0103] In some embodiments, the cutting process must ensure that the edges of each micro-LED chip are not damaged to avoid affecting its optoelectronic performance. The cut micro-LED chips must undergo rigorous testing to ensure that their brightness, color consistency, and electrical performance meet the requirements.

[0104] The fabrication method for the micro-LED chip package structure in this embodiment ensures the package stability and display performance of the micro-LED chip through rational process control. Through metal pad design, filling process, temporary substrate bonding, and precise electrical connections, the damage resistance, color consistency, and long-term stability of the micro-LED chip are effectively improved. These technical measures are widely applicable to the manufacture of high-resolution, long-life micro-LED display devices.

[0105] As an alternative to the present invention, the materials used for the N-type base layer and the P-type base layer used in the present invention can be replaced by aluminum gallium indium phosphide. The packaging process and preparation method are similar to those of gallium nitride and will not be described in detail here.

[0106] 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 micro LED chip packaging structure, characterized in that: include, at least three micro LED chips, the micro LED chips being arranged in a triangle shape, and the size of the micro LED chips ranging from 1 micron x 1 micron to 400 microns x 400 microns; Each micro-LED chip includes N-type gallium nitride, a quantum well layer, and a P-type gallium nitride layer, and electrodes are in contact with the N-type gallium nitride layer and the P-type gallium nitride layer respectively; BCB, PI or PDMS material is filled between the micro LED chip and the transparent substrate, and the transparent substrate is made of sapphire, glass or quartz material; A metal pad is provided in the central area of ​​the three micro LED chips. The diameter of the metal pad is greater than 30 microns, and the distance between the metal pad and the metal ring is greater than 5 microns.

2. A method for preparing a micro LED chip, characterized in that: A micro-LED chip packaging structure according to claim 1, comprising the following steps: S1. Sequentially growing an N-type GaN layer, a quantum well layer, and a P-type GaN layer on a sapphire substrate; S2. Preparing a positive electrode in contact with the P-type gallium nitride layer and a negative electrode in contact with the N-type gallium nitride layer; S3. Control the size of the micro LED chip to be 1 micron × 1 micron to 400 microns × 400 microns.

3. The method for preparing a micro LED chip according to claim 2, wherein: The size of the sapphire substrate is four inches or six inches, and the angle between the edge of the micro LED chip and the flat edge of the substrate is 45°.

4. The method for preparing a micro LED chip according to claim 2, wherein: The micro-LED chips are peeled off from the sapphire substrate to a temporary substrate using laser technology, and the number of micro-LED chips peeled off each time is 1 / (M*N), where M and N are natural numbers greater than or equal to 2.

5. A method for preparing a micro-LED chip packaging structure, characterized in that: A micro-LED chip packaging structure according to claim 1, comprising the following steps: Sa. electrically connecting multiple micro-LED chips; Sb. The plurality of temporary substrates are sequentially bonded to the transparent substrate, wherein the bonding uses BCB, PI or PDMS bonding glue, and the flat edges of the substrates are aligned during the bonding process; The connection between the micro-LED chip and the transparent substrate uses a filling material.

6. The method for preparing a micro-LED chip packaging structure according to claim 5, characterized in that: The filling material is used to planarize the protruding portion of the micro LED chip, and the filling material is BCB, PI, PDMS, epoxy resin or silica gel.

7. The method for preparing a micro-LED chip packaging structure according to claim 5, characterized in that: The thickness of the filling material is controlled to be within 5 microns based on the height of the micro-LED chip electrode, and when the thickness of the filling layer is higher than the micro-LED chip electrode, excess filling material is removed by photolithography, dry etching, wet etching or laser ablation.

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