A miniature light-emitting diode chip, its fabrication method, and a display device.

Abstract

This application discloses a miniature light-emitting diode (LED) chip, its fabrication method, and a display device. The miniature LED chip includes: a substrate; an active layer covering one side surface of the substrate, the active layer comprising sequentially stacked electron-type semiconductor layers, multiple quantum well layers, and hole-type semiconductor layers; from a regional perspective, the active layer includes a light-emitting portion and a packaging portion, with a trench between the light-emitting portion and the packaging portion. A conductive metal layer is provided on the surface of the light-emitting portion away from the substrate. In this embodiment, by providing a light-emitting portion with a surface connected to electrodes in a designated area of ​​the active layer, and providing a packaging portion and trenches in the remaining active layer that do not have light-emitting capability, only the area containing the light-emitting portion within the active layer can emit light under current drive, thereby reducing the light-emitting area of ​​the chip without reducing its size.

Description

Technical Field

[0001] This application relates to the field of optoelectronics technology, specifically to a micro light-emitting diode chip, its fabrication method, and a display device. Background Technology

[0002] Micro LED display is a next-generation display technology that specifically refers to a display technology that uses self-emissive, micrometer-sized LEDs as light-emitting pixel units, and assembles them onto a driving panel to form a high-density LED array. Micro LED chips are characterized by their small size, high integration, and self-emissive nature. Compared to display devices based on traditional materials such as Liquid Crystal Display (LCD) and Organic Light-Emitting Diode (OLED), they offer significant advantages in brightness, resolution, contrast ratio, and thermal stability.

[0003] Mass transfer of miniature LED chips is currently a major technological challenge, primarily due to the extremely high packaging precision requirements and the extremely small chip size. Increasing the chip size would effectively alleviate these problems, but miniature LED chips often require low-current drive. Increasing the chip size without changing the drive current would reduce the current density on the chip, thereby affecting its light extraction efficiency. Summary of the Invention

[0004] This application provides a miniature light-emitting diode chip, a fabrication method, and a display device, which can increase the current density of the chip without reducing its size.

[0005] In a first aspect, embodiments of this application provide a miniature light-emitting diode chip, comprising:

[0006] Substrate;

[0007] An active layer covering one side surface of the substrate, the active layer comprising an electronic semiconductor layer, a multiple quantum well layer and a hole semiconductor layer stacked sequentially; the active layer comprising a light-emitting portion and a packaging portion, wherein, in at least one pair of opposing sides of the light-emitting portion, the packaging portion is provided on the side of each side away from the other side, and a trench is formed between the packaging portion and the light-emitting portion.

[0008] A metal layer located on the side of the light-emitting portion away from the substrate, the metal layer includes a first electrode and a second electrode, wherein the first electrode is electrically connected to the electron-type semiconductor layer for injecting electrons into the electron-type semiconductor layer, and the second electrode is electrically connected to the hole-type semiconductor layer for injecting holes into the hole-type semiconductor layer.

[0009] This application embodiment provides a light-emitting part with a surface-connected electrode in a designated area of ​​the active layer, and provides a packaging part and trenches in the remaining active layer that do not have the ability to emit light, so that only the area where the light-emitting part is located in the active layer can emit light under the drive of current, thereby reducing the light-emitting area of ​​the chip without reducing the chip size.

[0010] In some possible embodiments, along the arrangement direction of a pair of opposite sides of the light-emitting portion, the first electrode and the second electrode are located on both sides of the light-emitting portion, and a portion of the first electrode overlaps the light-emitting portion and is connected to the electronic semiconductor layer of the light-emitting portion through a via penetrating the hole semiconductor layer and the multiple quantum well layer;

[0011] A portion of the second electrode overlaps with the light-emitting portion to be electrically connected to the electronic semiconductor layer.

[0012] In some possible embodiments, the surface area of ​​the light-emitting part is the same as the preset light-emitting area, the center point of the preset light-emitting area is located above the center line of the light-emitting part, and the center line of the light-emitting part is the center line of the substrate.

[0013] In some possible embodiments, the trench and the surface of the package portion away from the substrate are covered with solder pads, and the height of the solder pads is the same as the height of the metal electrode.

[0014] In some possible embodiments, the thickness of the electronic semiconductor layer and the hole semiconductor layer is between 0.5 and 10 micrometers.

[0015] Secondly, embodiments of this application provide a method for fabricating a miniature light-emitting diode chip, the method comprising:

[0016] An active layer is coated on the surface of a substrate, the active layer comprising an electronic semiconductor layer, a multiple quantum well, and a hole semiconductor layer stacked sequentially;

[0017] The active layer is patterned to divide it into a light-emitting portion, an encapsulation portion located on both sides of the light-emitting portion, and a trench located between the encapsulation portion and the light-emitting portion adjacent to the encapsulation portion.

[0018] A metal layer is covered on the side of the light-emitting part away from the substrate. The metal layer includes a first electrode for injecting electrons into the electron-type semiconductor layer and a second electrode for injecting holes into the hole-type semiconductor layer.

[0019] In this embodiment, an active layer of the same size as the substrate is first laid on the substrate surface. The active layer is then patterned to divide it into light-emitting portions, packaging portions on both sides of the light-emitting portions, and trenches between the packaging portions and the light-emitting portions adjacent to the packaging portions. Finally, a connecting motor is provided on the surface of the light-emitting portion away from the substrate so that only the light-emitting portion in the active layer has the ability to emit light under current drive, thereby reducing the light-emitting area of ​​the chip without reducing the chip size.

[0020] In some possible embodiments, prior to patterning the active layer, the method further includes:

[0021] The preset light-emitting area is determined based on the driving current and desired current density of the micro LED chip;

[0022] The patterning process of the active layer includes:

[0023] The position of the light-emitting part on the active layer is determined according to the center point of the preset light-emitting area; wherein, the surface area of ​​the light-emitting part is the same as the preset light-emitting area, the center point of the preset light-emitting area is located above the center line of the light-emitting part, and the center line of the light-emitting part is the center line of the substrate;

[0024] A predetermined volume of a designated active layer is removed from the remaining active layer adjacent to the light-emitting part along the boundary of the light-emitting part;

[0025] The region where the designated active layer is removed is designated as the trench, and the light-emitting part and the active layer outside the trench are designated as the encapsulation part.

[0026] In some possible embodiments, the method further includes, prior to coating the substrate surface with the active layer:

[0027] The preset light-emitting area is determined to be smaller than the surface area of ​​the substrate;

[0028] The method further includes:

[0029] If the preset light-emitting area is not less than the surface area of ​​the substrate, then the substrate is enlarged in size; wherein the enlarged substrate size is not greater than the package size of the micro LED chip on the substrate.

[0030] In some possible embodiments, prior to patterning the active layer, the method further includes:

[0031] The preset light-emitting area is determined to be smaller than the surface area of ​​the expanded substrate;

[0032] The method further includes:

[0033] If the preset light-emitting area is not less than the surface area of ​​the expanded substrate, then after the active layer is covered on the substrate surface, the entire active layer covering the substrate surface will be used as the light-emitting part.

[0034] Thirdly, embodiments of this application provide a display device, including:

[0035] Display panel, used to display images;

[0036] A backlight module is located on the light-incident side of the display panel; the backlight module includes a micro light-emitting diode (LED) lamp board, on which micro LED chips as described in any of the first aspects above are distributed. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of a miniature light-emitting diode chip provided in an embodiment of this application;

[0038] Figure 2 A schematic diagram of mass transfer provided for an embodiment of this application;

[0039] Figure 3 A cross-sectional view of a miniature light-emitting diode chip 300 provided in an embodiment of this application;

[0040] Figure 4 Provided for the embodiments of this application Figure 3 The structure diagram of the active layer 302 shown in the figure is as follows;

[0041] Figure 5 This is a schematic diagram of the region division of the active layer 302 provided in an embodiment of this application;

[0042] Figure 6 This is a schematic diagram of electrode connections provided in an embodiment of this application;

[0043] Figure 7 This is a schematic diagram illustrating the placement of solder pads in the active layer, as provided in an embodiment of this application.

[0044] Figure 8 A flowchart illustrating the fabrication method of the miniature light-emitting diode chip provided in the embodiments of this application;

[0045] Figure 9 This is a schematic diagram of the structure of a conventional miniature light-emitting diode chip provided in the embodiments of this application;

[0046] Figure 10 A schematic diagram illustrating how to determine the light-emitting part is provided for embodiments of this application;

[0047] Figure 11 A schematic diagram comparing the chip provided in the embodiments of this application with a conventional chip;

[0048] Figure 12 This is another schematic diagram comparing the chip provided in the embodiments of this application with a conventional chip;

[0049] Figure 13 This is a schematic diagram of the chip fabrication process provided in the embodiments of this application;

[0050] Reference numerals: 301-substrate, 302-active layer, 303-metal layer, 3031-first electrode, 3032-second electrode, 401-electronic semiconductor layer, 402-multiple quantum well layer, 403-hole semiconductor layer, 501-light-emitting part, 502-packaging part, 503-trench, 600-pad. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Unless otherwise specified, the embodiments and features in the embodiments of this application can be arbitrarily combined with each other. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than that shown here.

[0052] The terms "first" and "second" in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the term "comprising" and any variations thereof are intended to cover non-exclusive protection. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses. The term "multiple" in this application can mean at least two, for example, two, three, or more, and is not limited by the embodiments of this application.

[0053] To facilitate understanding of the technical solutions provided in the embodiments of this application, a brief introduction to the miniature light-emitting diode chip is given first. Specifically, as follows... Figure 1As shown, a micro-LED chip refers to a high-density, micro-sized LED array structure integrated on a chip. Compared to conventional LED chips, it can achieve the requirements of thin-film and miniaturization. The size of a single micro-LED chip can be less than 10 micrometers (μm), which is 1% of the size of a conventional LED chip. Each pixel on a micro-LED chip has the ability to be addressed and driven to emit light independently. The above technology reduces the pixel distance from the millimeter level to the micrometer level, giving the chip self-emissive display characteristics. As can be seen from the above, the current size of micro-LED chips has reached below 100 micrometers. Traditional LED chips are typically larger than 200 μm, while micro-LED chips are shrunk to less than 50 μm. Taking a 4K display screen as an example, the number of micrometer-sized chips that need to be transferred is as high as 24 million (calculated as 3840x2160 x RGB three-color LEDs). Even if 10,000 chips are transferred at a time, it would need to be repeated 2,400 times. Related technologies often use mass transfer technology to encapsulate micro-LED chips.

[0054] Mass transfer technology refers to the transfer of a large number of miniature light-emitting diode (LED) chips from a source substrate to a target substrate or driver circuit board using high-precision equipment. The industry has developed various approaches based on different technical principles, but mainstream technologies all involve two key processes: substrate separation and chip placement / removal. The specific transfer process is as follows: Figure 2 As shown, the chip is first separated from the source substrate by a certain force (such as magnetic force), and then the separated miniature light-emitting diode chip is transferred with high precision from the source substrate to the packaging area of ​​the target display substrate through a transfer device. Currently, the main problems with mass transfer technology are as follows: the thickness of the epitaxial layer of the light-emitting diode crystal to be transferred is only about 3% of the original light-emitting diode thickness, and a single transfer requires moving tens of thousands or even hundreds of thousands of light-emitting diodes, resulting in a very large number of transfers. Therefore, highly precise and meticulous operations are required to ensure product yield.

[0055] Increasing the chip size would effectively alleviate the difficulty of mass transfer operations. However, micro LED chips often require low-current drive. Increasing the chip size without changing the drive current would reduce the current density on the chip, thus affecting the chip's light extraction efficiency. To solve the above problems, this application provides a micro LED chip, a fabrication method, and a display device. Specifically, it provides a light-emitting portion with a surface covered by a connected electrode within the active layer, and a packaging portion without a connected electrode and a trench within the remaining active layer (excluding the light-emitting portion). This ensures that only the light-emitting portion within the active layer has the ability to emit light under current drive, thereby reducing the chip's light-emitting area without reducing the chip size.

[0056] Figure 3A cross-sectional view of a miniature light-emitting diode chip 300 provided in an embodiment of this application is shown below. Figure 3 As shown, the micro LED chip 300 specifically includes: a substrate 301, an active layer 302 covering one side surface of the substrate 301, and a metal layer 303 disposed on the side of the active layer 302 away from the substrate 301. The active layer 302 is stacked sequentially from bottom to top as follows: Figure 4 The electronic semiconductor layer 401 shown in the figure (i.e. Figure 4 The N-type semiconductor layer shown in the figure, the multiple quantum well layer 402 covering the surface of the electronic semiconductor layer 401 away from the substrate 301, and the hole-type semiconductor layer 403 covering the surface of the multiple quantum well layer 402 away from the substrate 301 (i.e., the N-type semiconductor layer), the multiple quantum well layer 402 covering the surface of the multiple quantum well layer 402 away from the substrate 301 (i.e., the hole-type semiconductor layer 403) Figure 4 (The P-type semiconductor layer shown in the figure). It should be understood that the substrate 301, the electronic semiconductor layer 401, the multiple quantum well layer 402, and the hole semiconductor layer 403 all have the same surface area.

[0057] In some possible embodiments, the thicknesses of the electronic semiconductor layer 401 and the hole semiconductor layer 403 are between 0.5 and 10 micrometers.

[0058] From a regional perspective, the region where the active layer 302 is located can be divided as follows: Figure 5 The diagram shows a light-emitting portion 501, a packaging portion 502, and a trench 503 disposed between the light-emitting portion 501 and the packaging portion 502. A metal layer 303 is provided on the surface of the light-emitting portion 501 away from the substrate 301. The metal layer 303 includes a first electrode 3031 (i.e.,...). Figure 5 The P-type electrode shown in the figure) and the second electrode 3032 (i.e. Figure 5 (N-type electrode shown in the image).

[0059] The specific connection method between the first electrode 3031, the second electrode 3032, and the light-emitting part 501 is as follows: Figure 6 As shown, specifically, along the arrangement direction of a pair of opposite sides of the light-emitting portion 501, the first electrode 3031 and the second electrode 3032 are located on both sides of the light-emitting portion 501. A portion of the first electrode 3031 overlaps with the light-emitting portion 501 and is connected to the electron-type semiconductor layer 401 of the light-emitting portion 501 through a via penetrating the hole-type semiconductor layer 403 and the multiple quantum well layer. A portion of the second electrode 3032 overlaps with the light-emitting portion 501 to be electrically connected to the electron-type semiconductor layer 401. That is, the first electrode 3031 is electrically connected to the electron-type semiconductor layer 401 for injecting electrons into the electron-type semiconductor layer 401, and the second electrode 3032 is electrically connected to the hole-type semiconductor layer 403 for injecting holes into the hole-type semiconductor layer 403.

[0060] In the above structure, under current drive, only the light-emitting portion 501 within the active layer 302 of the micro LED chip 300 can conduct current through the first electrode 3031 and the second electrode 3032 disposed on the light-emitting portion 501, causing the light-emitting portion 501 to emit light. The remaining area of ​​the active layer 302 (the encapsulation portion 502 and the trench 503) does not have the ability to emit light. Therefore, without reducing the chip size, the current density on the chip can be increased by reducing the light-emitting area of ​​the chip.

[0061] Currently, the size of micro-LED chips typically differs significantly from the size of the packaging area reserved for them on the display substrate. The solution provided in this application allows for the free setting of the substrate size of the micro-LED chip 300 based on its corresponding packaging size on the display substrate. Specifically, a preset light-emitting area corresponding to the micro-LED chip 300 can be calculated based on its driving current and desired current density, and the surface area of ​​the light-emitting portion 501 can be set to be the same as the preset light-emitting area. Therefore, while ensuring that the substrate size of the micro-LED chip does not exceed the corresponding packaging size, it is possible to reduce the engineering difficulty of mass transfer by increasing the size of the micro-LED chip without increasing its light-emitting area. Furthermore, it is possible to increase the current density of the micro-LED chip by reducing its light-emitting area without reducing its size.

[0062] For example Figure 7 As shown, in this embodiment, the surface of the trench 503 and the package portion 502 away from the substrate 301 is covered with a solder pad 600, and the thickness of the solder pad 600 is the same as the height of the metal electrodes (first electrode 3031 and second electrode 3032). This ensures that the surface of the micro LED chip 300 away from the substrate 301 is at the same horizontal plane, thus avoiding increased engineering difficulty during mass transfer due to uneven chip surface area.

[0063] Furthermore, based on the micro light-emitting diode chip provided in the embodiments of this application, the embodiments of this application also provide a method for fabricating the micro light-emitting diode chip, specifically as follows: Figure 8 As shown, it includes the following steps:

[0064] Step 801: Cover the substrate surface with an active layer, the active layer comprising an electronic semiconductor layer, a multiple quantum well and a hole semiconductor layer stacked sequentially; pattern the active layer to divide the active layer into a light-emitting portion, a packaging portion located on both sides of the light-emitting portion, and a trench located between the packaging portion and the light-emitting portion adjacent to the packaging portion.

[0065] Step 802: Cover the surface of the light-emitting part away from the substrate with a metal layer, the metal layer including a first electrode for injecting electrons into the electron-type semiconductor layer and a second electrode for injecting holes into the hole-type semiconductor layer.

[0066] like Figure 9 As shown, the typical fabrication process for a micro LED chip involves epitaxial growth on a substrate using MOCVD (Metal-on-Chip Vacuum Diode) in a high-temperature vacuum environment, incorporating MO source gas, ammonia (NH3), and hydrogen (H2) to grow an N-type semiconductor, a quantum well (MQW), and a P-type semiconductor sequentially from bottom to top. This is followed by chip fabrication, which involves multiple steps to create a chip like... Figure 9 The image shows a conventional miniature light-emitting diode (LED) chip. Since the driving current of a miniature LED chip is typically very small, usually in the microamp (µA) or nanoamp (nA) range, the current density calculated based on the driving current and chip area is usually lower than the preset current density corresponding to the ideal maximum photoelectric conversion efficiency. To solve the above problem, this embodiment of the application prepares the miniature LED chip 300 described in the above process through steps 801-802. This miniature LED chip 300 provides a light-emitting portion with a surface-covered connected electrode within the active layer, and provides a packaging portion and trenches without connected electrodes in the remaining active layer of the non-light-emitting portion. This ensures that only the light-emitting portion within the active layer has the ability to emit light under current drive, thereby reducing the light-emitting area of ​​the chip without reducing its size.

[0067] Specifically, the size of current micro-LED chips typically differs significantly from the size of the packaging area reserved for them on the display substrate. By freely setting the substrate size of the micro-LED chip based on its corresponding packaging size on the display substrate, and ensuring that the substrate size does not exceed the corresponding packaging size, a light-emitting portion can be partitioned from the active layer grown on the substrate surface. By controlling the surface area of ​​the light-emitting portion to be the same as the preset light-emitting area, it is possible to increase the size of the micro-LED chip without increasing its light-emitting area, thus reducing the engineering difficulty of mass transfer. Conversely, it is possible to increase the current density of the micro-LED chip by reducing its light-emitting area without reducing its size.

[0068] Before performing step 801, the preset light-emitting area needs to be determined based on the driving current and desired current density of the micro LED chip. During step 801, the position of the light-emitting part in the active layer needs to be determined based on the center point of the preset light-emitting area. Specifically... Figure 10As shown, firstly, the centerline of the substrate is used as the centerline of the light-emitting part. Then, on the surface of the active layer away from the substrate, a target surface area equal to the preset light-emitting area is cut off with this centerline as the center point. The active layer corresponding to the target surface area is then used as the light-emitting part. This is equivalent to the surface area of ​​the light-emitting part being the same as the preset light-emitting area, and the center point of the preset light-emitting area being located above the centerline of the light-emitting part. Therefore, while increasing the chip size, the current density of the chip can still meet engineering requirements.

[0069] After determining the light-emitting portion within the active layer, a predetermined volume of a designated active layer needs to be removed from the remaining active layers adjacent to the light-emitting portion along the boundary of the light-emitting portion. In this embodiment, the area where the designated active layer is removed is designated as a trench, and the light-emitting portion and the active layer outside the trench are designated as a packaging portion. It should be understood that the purpose of removing the designated active layer to form a trench is to reduce the volume of the light-emitting portion within the active layer, i.e., to reduce the light-emitting area of ​​the micro LED chip. Furthermore, the predetermined volume of the designated active layer can be set according to actual needs, but it must be ensured that after removing the designated active layer, a certain volume of active layer (i.e., packaging portion) still exists in the light-emitting portion and the trench. This can be achieved by covering the surface of the packaging portion with a pad of the same height as the metal electrode to ensure that the surface of the micro LED chip away from the substrate is at the same level, thereby avoiding the problem of increased engineering difficulty in the mass transfer process due to uneven chip surface area. Specifically, as follows... Figure 11 As shown, Figure 11 The image above shows a miniature light-emitting diode chip 1 prepared using conventional processing methods. Figure 11 The image below shows a miniature light-emitting diode chip 2 obtained through the fabrication process described above in this application. A comparison shows that chip 1 and chip 2 have the same dimensions, but the light-emitting area of ​​chip 2 is only the surface area of ​​the light-emitting portion, while the light-emitting area of ​​chip 1 is the surface area of ​​the entire active layer. Therefore, the fabrication method provided in this application can reduce the light-emitting area of ​​the chip without reducing its size, thereby increasing the chip's current density.

[0070] Furthermore, after determining the preset light-emitting area, the chip size can be increased by expanding the substrate size, thereby reducing the engineering difficulty of mass transfer. Specifically, for example... Figure 12 As shown, Figure 12 The image above shows a miniature light-emitting diode chip 1 prepared using conventional processing methods. Figure 12The image below shows a miniature light-emitting diode chip 2 obtained through the fabrication process described above in this application. It is assumed that the preset light-emitting area is equal to the initial size of the chip substrate, meaning the preset light-emitting area is equal to the surface area of ​​the active layer grown on the substrate. A comparison shows that chip 2 is larger than chip 1, but the light-emitting area of ​​chip 2 is the same as that of chip 1. Therefore, the fabrication method provided in this application can increase the chip size without increasing the light-emitting area, thereby reducing the engineering difficulty of mass transfer.

[0071] After determining the light-emitting portion, encapsulation portion, and trenches within the active layer through the above process, solder pads need to be covered on the surface of the encapsulation portion. The length of the solder pads is extended so that they cover the surface of the trenches adjacent to the encapsulation portion until the solder pads connect with the electrode layer on one side of the adjacent trench. Furthermore, the solder pads covering the surface of the encapsulation portion are polished to ensure that the processed solder pads have the same height as the electrode layer. This ensures that the surface of the micro-LED chip away from the substrate is at the same level, avoiding increased engineering difficulty during mass transfer due to uneven chip surface area.

[0072] Furthermore, considering that although the calculated preset light-emitting area is usually smaller than the chip size, there are inevitably cases where the preset light-emitting area is not smaller than the chip size (i.e., the preset light-emitting area is not smaller than the surface area of ​​the substrate). In this case, the size of the chip substrate can be expanded to maximize the chip's light-emitting area. It should be noted that the expanded substrate size must not exceed the package size of the micro LED chip on the substrate to avoid the expanded chip size being too large to be packaged onto the display substrate.

[0073] In some possible embodiments, if the preset light-emitting area is not less than the surface area of ​​the expanded substrate, then after covering the substrate surface with an active layer, the entire active layer covering the substrate surface is used as the light-emitting part.

[0074] To facilitate understanding of how the fabrication method of a micro LED chip provided in the embodiments of this application is performed based on the preset light-emitting area of ​​the chip in the above process of this application, the specific details are as follows: Figure 13 As shown, it includes:

[0075] Step 1301: Determine the preset light-emitting area based on the driving current and desired current density of the micro LED chip;

[0076] Step 1302: Apply an active layer to the substrate surface of a predetermined size according to engineering requirements using a patterning process;

[0077] Step 1303: Expand the size of the substrate and cover the surface of the expanded substrate with an active layer; it should be noted that the size of the expanded substrate is not larger than the package size of the micro LED chip on the substrate;

[0078] Step 1304: Determine the position of the light-emitting part in the active layer according to the center point of the preset light-emitting area; wherein, the surface area of ​​the light-emitting part is the same as the preset light-emitting area, the center point of the preset light-emitting area is located above the center line of the light-emitting part, and the center line of the light-emitting part is the center line of the substrate.

[0079] Step 1305: Remove a predetermined volume of a designated active layer from the remaining active layer adjacent to the light-emitting part along the boundary of the light-emitting part, and use the area where the designated active layer is removed as a trench, and use the light-emitting part and the active layer outside the trench as an encapsulation part.

[0080] Step 1306: Cover the surface of the package with solder pads and extend the solder pads so that they extend and cover the surface of the trench adjacent to the package until the solder pads are connected to the electrode layer on one side of the adjacent trench.

[0081] Step 1307: Polish the solder pads covering the surface of the package to make the solder pads have the same height as the electrode layer.

[0082] Step 1308: Cover the surface of the light-emitting part away from the substrate with a metal layer; the metal layer includes a first electrode for injecting electrons into the electron-type semiconductor layer and a second electrode for injecting holes into the hole-type semiconductor layer.

[0083] In the above process, the embodiments of this application can determine the preset light-emitting area based on the driving current and desired current density of the micro LED chip, and then set the substrate size of the chip based on the preset light-emitting area. Therefore, according to actual needs, the engineering difficulty of mass transfer can be reduced by increasing the chip size without increasing the chip's light-emitting area. Alternatively, the current density of the chip can be increased by reducing the chip's light-emitting area without reducing the chip size.

[0084] It should be noted that the fabrication method of the micro LED chip in the above embodiments of this application may include more steps, which can be determined according to actual needs. The embodiments of this application do not limit this, and the detailed description and technical effects can be found in the description of the micro LED chip above, which will not be repeated here. In addition, in the fabrication method of the micro LED chip provided in the embodiments of this application, the specific process and fabrication procedure of steps 801 and 802 are not limited to the embodiments given above, and other process methods and steps can also be used for fabrication. For details, please refer to the description of each layer structure in the micro LED chip above, which will not be repeated here.

[0085] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A miniature light-emitting diode chip, characterized in that, include: Substrate; An active layer covering one side surface of the substrate, the active layer comprising an electronic semiconductor layer, a multiple quantum well layer and a hole semiconductor layer stacked sequentially; the active layer comprising a light-emitting portion and a packaging portion, wherein, in at least one pair of opposing sides of the light-emitting portion, the packaging portion is provided on the side of each side away from the other side, and a trench is formed between the packaging portion and the light-emitting portion. A metal layer located on the side of the light-emitting portion away from the substrate, the metal layer includes a first electrode and a second electrode, wherein the first electrode is electrically connected to the electron-type semiconductor layer for injecting electrons into the electron-type semiconductor layer, and the second electrode is electrically connected to the hole-type semiconductor layer for injecting holes into the hole-type semiconductor layer.

2. The micro light-emitting diode chip according to claim 1, characterized in that, Along the arrangement direction of a pair of opposite sides of the light-emitting part, the first electrode and the second electrode are located on both sides of the light-emitting part. A portion of the first electrode overlaps the light-emitting part and is connected to the electronic semiconductor layer of the light-emitting part through a via penetrating the hole semiconductor layer and the multiple quantum well layer. A portion of the second electrode overlaps with the light-emitting portion to be electrically connected to the electronic semiconductor layer.

3. The miniature light-emitting diode chip according to claim 1, characterized in that, The surface area of ​​the light-emitting part is the same as the preset light-emitting area, the center point of the preset light-emitting area is located above the center line of the light-emitting part, and the center line of the light-emitting part is the center line of the substrate.

4. The micro light-emitting diode chip according to claim 1, characterized in that, The trench and the surface of the package portion away from the substrate are covered with solder pads, and the height of the solder pads is the same as the height of the metal electrode.

5. The micro light-emitting diode chip according to any one of claims 1-4, characterized in that, The thickness of the electronic semiconductor layer and the hole semiconductor layer is between 0.5 and 10 micrometers.

6. A method for fabricating a miniature light-emitting diode chip, characterized in that, The method includes: An active layer is deposited on the surface of a substrate. The active layer includes an electronic semiconductor layer, a multiple quantum well, and a hole semiconductor layer stacked sequentially. The active layer is patterned to divide the active layer into a light-emitting portion, a packaging portion located on both sides of the light-emitting portion, and a trench located between the packaging portion and the light-emitting portion adjacent to the packaging portion. A metal layer is covered on the side of the light-emitting part away from the substrate. The metal layer includes a first electrode for injecting electrons into the electron-type semiconductor layer and a second electrode for injecting holes into the hole-type semiconductor layer.

7. The method according to claim 6, characterized in that, Before patterning the active layer, the method further includes: The preset light-emitting area is determined based on the driving current and desired current density of the micro LED chip; The patterning process of the active layer includes: The position of the light-emitting part on the active layer is determined according to the center point of the preset light-emitting area; wherein, the surface area of ​​the light-emitting part is the same as the preset light-emitting area, the center point of the preset light-emitting area is located above the center line of the light-emitting part, and the center line of the light-emitting part is the center line of the substrate; A predetermined volume of a designated active layer is removed from the remaining active layer adjacent to the light-emitting part along the boundary of the light-emitting part; The region where the designated active layer is removed is designated as the trench, and the light-emitting part and the active layer outside the trench are designated as the encapsulation part.

8. The method according to claim 6, characterized in that, Before coating the substrate surface with an active layer, the method further includes: The preset light-emitting area is determined to be smaller than the surface area of ​​the substrate; The method further includes: If the preset light-emitting area is not less than the surface area of ​​the substrate, then the substrate is enlarged in size; wherein the enlarged substrate size is not greater than the package size of the micro LED chip on the substrate.

9. The method according to claim 8, characterized in that, Before patterning the active layer, the method further includes: The preset light-emitting area is determined to be smaller than the surface area of ​​the expanded substrate; The method further includes: If the preset light-emitting area is not less than the surface area of ​​the expanded substrate, then after the active layer is covered on the substrate surface, the entire active layer covering the substrate surface will be used as the light-emitting part.

10. A display device, characterized in that, include: Display panel, used to display images; The backlight module is located on the light-incident side of the display panel; The backlight module includes a miniature light-emitting diode (LED) board, on which miniature LED chips as described in any one of claims 1-5 are distributed.

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