Micro LED chip and preparation method

Abstract

The application discloses a Micro LED chip and a preparation method thereof. The Micro LED chip comprises a driving panel, a plurality of LED units arranged in an array on the driving panel, a grid structure surrounding the plurality of LED units to form a plurality of grid holes arranged in an array, and a plurality of microlenses arranged in the grid holes and having a light-collecting convex surface facing the LED units. Light emitted by the LED units can be emitted from a side of the microlenses away from the LED units after passing through the light-collecting convex surface. The microlenses are formed on the LED units and have the light-collecting convex surface facing the LED units, so that the light emitted by the LED units can be effectively collected after passing through the light-collecting convex surface, the light emission amount of the light emitted from the side of the microlenses away from the LED units is improved, and the efficiency and stability of full-color display of the Micro LED chip are improved.

Description

Technical Field

[0001] This application relates to the field of LED display technology, and in particular to a Micro LED chip and its fabrication method. Background Technology

[0002] In existing Micro LED chips, microlenses are mostly directly covered on the LED unit, and the surface facing away from the LED unit is a raised surface that bulges outward. This allows the light emitted by the LED unit to be focused when it exits through the raised surface. However, the light emitted by the LED unit is scattered light, and the focusing effect is not good after passing through the microlens with this structure, resulting in low light utilization. Summary of the Invention

[0003] To address the problems existing in the prior art, this application provides a Micro LED chip and its fabrication method, the technical solution of which is as follows:

[0004] On one hand, this application provides a Micro LED chip, comprising:

[0005] Driver panel;

[0006] Multiple LED units are arranged in an array on the drive panel;

[0007] A grid structure, comprising multiple grid holes arranged in an array around multiple LED units;

[0008] Multiple microlenses are disposed in the grid holes, and the surface of the microlens facing the LED unit is a light-concentrating convex surface. The light emitted by the LED unit can pass through the light-concentrating convex surface and then exit from the side of the microlens away from the LED unit.

[0009] Furthermore, there is a cavity between the microlens and the LED unit, and the light emitted by the LED unit can pass through the cavity and the focusing convex surface, and then exit from the side of the microlens away from the LED unit.

[0010] Furthermore, the refractive index of the microlens is greater than that of the cavity.

[0011] Furthermore, the microlens is used to focus and / or collimate the light emitted from the LED unit into the cavity.

[0012] Furthermore, the ratio between the radius of curvature of the light-concentrating convex surface and the lateral dimension of the light-emitting surface of the LED unit is 0.15 to 18.

[0013] Furthermore, the light-emitting surface of the LED unit is located at the focal plane of the microlens.

[0014] Furthermore, the microlens includes a stacked transparent support layer and a lens body. The transparent support layer is located between the lens body and the cavity. The transparent support layer has a recessed structure facing the LED unit, and the light-concentrating convex surface is located on the side of the transparent support layer away from the lens body.

[0015] Furthermore, the Micro LED chip also includes a color conversion layer, which covers the side of the microlens facing away from the LED unit.

[0016] Furthermore, the lateral dimension of the grid aperture gradually increases from the side closer to the LED unit to the side farther away from the LED unit.

[0017] Furthermore, the Micro LED chip also includes a reflective layer that at least covers the sidewalls of the grid aperture.

[0018] Furthermore, the material of the microlens includes at least one of transparent photoresist, transparent organic resin, silicon dioxide, silicon nitride, and aluminum oxide.

[0019] On the other hand, this application also provides a method for fabricating a Micro LED chip, comprising:

[0020] A driving panel is provided; the driving panel is provided with a grid structure and multiple LED units arranged in an array, the grid structure surrounding the multiple LED units to form multiple grid holes arranged in an array;

[0021] Multiple microlenses are formed on the driving panel; the microlenses are disposed in the grid holes, and the surface facing the LED unit is a light-concentrating convex surface, so that the light emitted by the LED unit can pass through the light-concentrating convex surface and exit from the side of the microlenses away from the LED unit.

[0022] Furthermore, a cavity exists between the microlens and the LED unit; forming multiple microlenses on the driving panel includes:

[0023] A sacrificial layer is formed in the grid holes; the sacrificial layer covers the LED unit, and the surface of the sacrificial layer is a concave surface recessed towards the LED unit;

[0024] The microlens is formed on the sacrificial layer, and the sacrificial layer is removed to form the cavity between the microlens and the LED unit.

[0025] Further, the microlens includes a transparent support layer and a lens body; the process of forming the microlens on the sacrificial layer and removing the sacrificial layer to form the cavity between the microlens and the LED unit includes:

[0026] The transparent support layer is formed on the sacrificial layer; the transparent support layer has a structure that is recessed toward the LED unit.

[0027] Remove the sacrificial layer to form the cavity between the transparent support layer and the LED unit;

[0028] The lens body is formed on the transparent support layer to obtain the microlens.

[0029] Furthermore, the light-concentrating convex surface and the concave surface of the sacrificial layer are conformally arranged.

[0030] Furthermore, after forming a plurality of microlenses on the drive panel, the method further includes:

[0031] A color conversion layer is formed on the side of the microlens opposite to the LED unit.

[0032] Implementing this application will have the following beneficial effects:

[0033] 1. The microlens of this application has a focusing convex surface facing the LED unit. The light emitted by the LED unit can be effectively focused after passing through the focusing convex surface, which means that the scattered light from the LED unit light source can be effectively focused and / or collimated. More light can be emitted on the side of the microlens away from the LED unit, increasing the light output of the light source. It also makes it easier for the light to enter the color conversion layer after emission and be utilized, improving the color conversion efficiency and greatly improving the efficiency of full-color display of Micro LED chips.

[0034] 2. This application forms a cavity between the LED unit and the microlens. The light emitted by the LED unit first passes through the cavity and then through the focusing convex surface, which can be further focused. This synergistically enables the scattered light from the LED unit light source to be effectively focused and / or collimated, further increasing the light output of the light source. It also facilitates the light to enter the color conversion layer after emission and be utilized, improving the color conversion efficiency and greatly enhancing the efficiency of full-color display of Micro LED chips.

[0035] 3. In this application, the color conversion layer is located on the side of the microlens away from the LED unit, and there is a cavity gap between the microlens and the LED unit. This avoids direct contact between the color conversion layer and the LED unit, and also avoids the aging of the color conversion layer material under high temperature conditions caused by the strong light intensity emitted by the LED unit. This effectively reduces the heat conduction of blue light, increases the aging threshold of the material in the MicroLED chip, and improves the stability, reliability and lifespan of the full-color display of the MicroLED chip. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in the embodiments will be briefly described below, wherein the same components are represented by the same reference numerals. Obviously, the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0037] Figure 1 This is a schematic diagram of the structure of a Micro LED chip provided in an embodiment of this application;

[0038] Figure 2 A schematic diagram of the optical path of the light emitted by the LED unit in some exemplary embodiments provided in this application;

[0039] Figure 3 A schematic diagram of a driving panel with LED units provided in an embodiment of this application;

[0040] Figure 4 This application provides a schematic diagram of a drive panel with a grid structure as an embodiment of the present application.

[0041] Figure 5 This is a schematic diagram of a structure obtained after forming a sacrificial layer, provided in an embodiment of this application.

[0042] Figure 6 This is a schematic diagram of the structure obtained after forming a transparent support layer, provided in an embodiment of this application.

[0043] Figure 7 This is a schematic diagram of the structure obtained after removing the sacrificial layer, provided in an embodiment of this application.

[0044] Figure 8 This is a schematic diagram of a structure obtained after forming a microlens, as provided in an embodiment of this application.

[0045] The attached figures are labeled as follows:

[0046] 100-Driver panel, 101-First contact, 102-Second contact, 200-LED unit, 201-First electrode, 202-Light-emitting layer, 203-Second electrode, 204-Bonding layer, 205-Passivation layer, 300-Grid structure, 301-Grid hole, 400-Microlens, 401-Concentrating convex surface, 402-Transparent support layer, 403-Lens body, 500-Cavity, 510-Sacrificial layer, 600-Color conversion layer, 700-Reflective layer. Detailed Implementation

[0047] The technical solutions of 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 the embodiments, and therefore should not be construed as limiting this application. 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.

[0048] It should be noted that, in the description of this application, the following definitions shall apply unless a different definition is given elsewhere in the claims or this specification. All numerical values, whether or not explicitly indicated, are defined herein as being modified by the term "about". The term "about" generally refers to a range of numerical values ​​that a person skilled in the art would consider equivalent to the stated values ​​to produce substantially the same properties, functions, results, etc. A range of numerical values ​​indicated by a low value and a high value is defined as including all numerical values ​​within that range and all subranges included within that range.

[0049] It should be noted that the terms "first," "second," etc., used in the specification, claims, and drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such uses of the terms can be interchanged where appropriate so that embodiments of this application can be implemented in an order other than that shown in the figures or descriptions below. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, or product that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, or products.

[0050] In this application's specification, claims, and drawings, "layer" refers to a portion of material comprising a region of a certain thickness. A layer may extend over the entire underlying or upper layer structure, or may have a extent smaller than that of the underlying or upper layer structure. Furthermore, a layer may be a region of a homogeneous or heterogeneous continuous structure with a thickness less than the thickness of the continuous structure. For example, a layer may be located between the top and bottom surfaces of a continuous structure, or between any pair of horizontal planes therebetween. A layer may extend horizontally, vertically, and / or along a tapered surface. Layers may comprise multiple layers. For example, a semiconductor layer may comprise one or more doped or undoped semiconductor layers, and may have the same or different materials.

[0051] To address the issues of unsatisfactory light-gathering effect and low light utilization in existing Micro LED chips, this application provides a Micro LED chip and its fabrication method. The Micro LED chip includes a driving panel, multiple LED units, a grid structure, and multiple microlenses. Multiple LED units are arrayed on the driving panel, and the grid structure surrounds the multiple LED units to form multiple grid holes. Microlenses are disposed within these grid holes, with one surface facing the LED unit being a focusing convex surface. Light emitted from the LED unit passes through this focusing convex surface and exits from the side of the microlens away from the LED unit. Furthermore, compared to traditional microlens structures, this inverted microlens design effectively gathers the light emitted by the LED unit at the focusing convex surface, allowing more light to exit from the side of the microlens away from the LED unit. This significantly increases the light output of the LED unit and further enhances the color conversion efficiency of the emitted light entering the color conversion layer, thereby improving the efficiency and stability of full-color display using the Micro LED chip.

[0052] The method for fabricating this Micro LED chip involves several steps. First, a driving panel is provided, which has a grid structure and multiple LED units arranged in an array. The grid structure surrounds the multiple LED units to form multiple grid holes. Next, multiple microlenses are formed on the driving panel. Each microlens is positioned within a grid hole, and its surface facing the LED unit is a light-concentrating convex surface. Light emitted from the LED unit can pass through the light-concentrating convex surface and exit from the side of the microlens away from the LED unit. This method for fabricating the Micro LED chip is simple and convenient, effectively improving the structural precision of the microlenses formed during the fabrication process. This significantly improves the fabrication accuracy and yield of the Micro LED chip, which is beneficial for enhancing the accuracy, stability, and reliability of full-color Micro LED displays and for improving the long-term performance of the Micro LED chip.

[0053] Please refer to the instruction manual below. Figure 1-2 The technical solutions of the embodiments of the present invention will be described in detail below. It is understood that the Micro LED chips in the accompanying drawings are only some specific embodiments of the technical solutions of this application. The Micro LED chips of this application may include fewer or more structural features, and are not intended to be limited to any particular embodiment. Figure 1-2 Limited to the structure described herein, for example, this Micro LED chip can be applied to, for example, Figure 1 The common cathode structure shown can also be applied to the common anode structure, making it widely applicable.

[0054] like Figure 1As shown, the Micro LED chip includes a driving panel 100, multiple LED units 200, a grid structure 300, and multiple microlenses 400. The multiple LED units 200 are arranged in an array on the driving panel 100. Each LED unit 200 can emit light as a light source and is also called a pixel. In some exemplary embodiments, the size of the LED unit 200 is 0.1μm to 10μm.

[0055] Among them, such as Figure 1 As shown, the driving panel 100 includes multiple contacts for connection to a driving circuit. Multiple LED units 200 are electrically connected to the multiple contacts to achieve individual control of the multiple LED units 200. In some exemplary embodiments, the multiple contacts include a first contact 101 and multiple second contacts 102. The first contact 101 can be electrically connected to the multiple LED units 200, and each second contact 102 can be electrically connected to one LED unit 200 respectively to drive any one of the multiple LED units 200 to emit light. Optionally, in a common cathode structure, the first contact 101 is a cathode contact and the second contact 102 is an anode contact. Alternatively, in a common anode structure, the first contact 101 is an anode contact and the second contact 102 is a cathode contact.

[0056] like Figure 1 As shown, the LED unit 200 includes a first electrode 201, a light-emitting layer 202, and a second electrode 203. The first electrode 201 covers the light-emitting layer 202 and is made of a transparent conductive material. The light emitted from the light-emitting layer 202 can be emitted from one side of the first electrode 201 to avoid affecting the light emission efficiency. At the same time, the first electrodes 201 of multiple LED units 200 are electrically connected to each other to form a common electrode. The second electrode 203 is located on the second contact 102 so that each LED unit 200 is individually electrically connected to the second contact 102 through the second electrode 203, thereby realizing individual control of each LED unit.

[0057] In some exemplary embodiments, the LED unit further includes a bonding layer 204, which is located between the second electrode 203 and the driving panel 100 to improve the bonding stability between the second electrode 203 and the driving panel; the bonding layer 204 is made of a conductive material so that the second electrode 203 can be electrically connected to the second electrode 203 through the bonding layer 204, thereby improving the reliability of the electrical connection.

[0058] In some exemplary embodiments, the LED unit further includes a passivation layer 205, which covers the sidewalls of the light-emitting layer 202, the second electrode 203, and the bonding layer 204, and partially covers the surface of the driving panel 100, so that adjacent LED units are spaced apart from each other; and the passivation layer 205 is also located between the first electrode 201 and the second electrode 203. The material of the passivation layer 205 has good electrical insulation to avoid short circuit between the first electrode 201 and the second electrode 203, thereby improving the stability and lifespan of the LED unit; in addition, it should be noted that the passivation layer 205 is a light-transmitting material and does not affect the light emission efficiency of the light-emitting layer 202.

[0059] In some exemplary embodiments, the LED unit 200 has a rectangular cross-section in the direction perpendicular to the surface of the driving panel 100, that is, the sidewalls of the LED unit 200 are perpendicular to the surface of the driving panel 100, and the LED unit 200 as a whole has a columnar structure; such as Figure 1 As shown, in some other exemplary embodiments, the LED unit 200 has a trapezoidal cross-section in the direction perpendicular to the surface of the driving panel 100, that is, the sidewall of the LED unit 200 is an inclined surface. From the side close to the driving panel 100 to the side away from the driving panel 100, the cross-sectional area of ​​the LED unit 200 gradually decreases, which can initially concentrate the light emitted by the LED unit 200, which is beneficial to improving the light-gathering effect of the LED unit 200.

[0060] like Figure 1 As shown, the grid structure 300 surrounds the multiple grid holes 301 in which the multiple LED units 200 are arranged in an array, spacing the multiple LED units 200 apart from each other. The end of the grid structure 300 near the driving panel 100 is located on the common electrode layer of the LED unit 200 (in the common cathode structure, the common electrode layer is a common cathode). The common electrode layer covers the driving panel 100, thereby spacing the multiple LED units 200 while avoiding affecting the conductivity of the multiple LED units 200.

[0061] That is, each LED unit 200 is respectively set in a grid hole 301. The number of grid holes 301 can be the same as or greater than the number of LED units 200, and the height of the grid structure 300 is greater than the height of the LED unit 200. On the one hand, it can focus the light emitted by the LED unit 200 to a certain extent, prevent cross-lighting between LED units 200, achieve good optical isolation, which is conducive to improving the light output of the LED unit 200 and improving the light emission accuracy. It can also achieve heat conduction to a certain extent, preventing heat accumulation from adversely affecting the long-term performance of the Micro LED chip. On the other hand, it is convenient to form a microlens 400 in the grid hole 301 during the fabrication process, so that the microlens 400 can better focus the light emitted by the LED unit 200, further improving the light output and light source utilization of the LED unit 200.

[0062] The material of the grid structure 300 may include at least one of organic resin, organic black matrix photoresist, color filter photoresist and polyimide. It should be noted that the above-mentioned material of the grid structure 300 is only an example and is not intended to limit this application. Materials that can collimate the light emitted by the LED unit 200 through reflection or refraction are all within the protection scope of this application.

[0063] Specifically, such as Figure 1 As shown, the lateral dimension of the grid hole 301 gradually increases from the side closer to the LED unit 200 to the side farther away from the LED unit 200. That is, the sidewall of the grid structure 300 is inclined, and the angle between the surface of the grid structure 300 away from the front drive panel 100 and the sidewall of the grid structure 300 is an obtuse angle. The grid structure 300 can further improve the effectiveness and efficiency of focusing and / or collimating the light emitted by the LED unit 200. It works in conjunction with the LED unit 200 with its inclined sidewall to greatly increase the light output of the LED unit 200. In some optional specific embodiments, the shape of the grid hole 301 can be a bowl shape or a trumpet shape.

[0064] Specifically, such as Figure 1 As shown, the Micro LED chip also includes a reflective layer 700, which covers at least the sidewall of the grid hole 301. It has high reflectivity and can effectively reflect the light emitted by the LED unit 200 to the surface of the reflective layer 700, thereby further increasing the light output of the LED unit 200. In addition, the reflective layer 700 can also work with the inclined side of the LED unit 200 to perform multiple reflections, which greatly improves the light utilization rate and luminous brightness of the LED unit 200.

[0065] In some exemplary embodiments, the reflective layer 700 may cover the sidewall of the grid aperture 301; in other exemplary embodiments, the reflective layer 700 covers the sidewall of the grid aperture 301 and the side surface of the grid structure 300 facing away from the drive panel 100.

[0066] The reflective layer 700 is made of organic and inorganic materials. The organic materials include high-reflectivity organic coatings, and the inorganic materials include metallic materials such as aluminum, copper, and silver. The high reflectivity is beneficial to improving the light output of the LED unit 200 and also to improving the full-color display quality of the Micro LED chip. In some preferred embodiments, the reflective layer 700 is made of metallic materials, which is beneficial to improving the overall light output.

[0067] like Figure 1 As shown, the microlens 400 is disposed in the grid hole 301, that is, each microlens 400 is disposed in a grid hole 301. In the same grid hole 301, the microlens 400 is located on the side of the LED unit 200 away from the driving panel 100, and the surface facing the LED unit 200 is a light-concentrating convex surface 401. The light emitted by the LED unit 200 can pass through the light-concentrating convex surface 401 and then exit from the side of the microlens 400 away from the LED unit 200. The light-concentrating convex surface 401 plays the role of converging the light, which enables more light emitted by the LED unit 200 to exit from the side of the microlens 400 away from the LED unit 200, thereby improving the light output of the LED unit 200 and the subsequent light utilization rate. The surface of the microlens 400 away from the LED unit 200 can be a plane, a convex surface or a concave surface, and this application does not make a specific limitation on this.

[0068] Specifically, such as Figure 1 As shown, there is a cavity 500 between the microlens 400 and the LED unit 200. The light-concentrating convex surface 401 is located at the interface between the cavity 500 and the microlens 400. The light emitted by the LED unit 200 can pass through the cavity 500 and the light-concentrating convex surface 401 and then exit from the side of the microlens 400 away from the LED unit 200, further enhancing the light-concentrating effect, increasing the light output of the LED unit 200 and the subsequent light utilization rate.

[0069] Specifically, the microlens 400 and the cavity 500 have different refractive indices for light. The refractive index of the microlens 400 is greater than that of the cavity 500, meaning that the refractive index of the material of the microlens 400 is greater than that of the gas in the cavity 500. The light emitted by the LED unit 200 first enters the cavity 500, and then passes through the focusing convex surface 401 and enters the microlens 400. Since the refractive index of the microlens 400 is higher than that of the cavity 500, refraction can occur at the interface between the two, i.e., at the focusing convex surface 401, so that the scattered light emitted by the LED unit 200 is effectively focused, achieving collimation of the light source emitted by the LED unit 200. For example, in some exemplary embodiments, the gas in the cavity 500 is air with a refractive index of 1.

[0070] Specifically, the microlens 400 is used to focus and / or collimate the light emitted from the LED unit 200 to the cavity 500, such as... Figure 2 As shown, the microlens 400 is a convex lens that protrudes towards the LED unit 200, and the focusing convex surface 401 is a curved surface that protrudes towards the LED unit 200. The microlens 400 has a high refractive index, so the scattered light will be refracted when it reaches the focusing convex surface 401. The angle of refraction after refraction is smaller than the angle of incidence when it reaches the focusing convex surface 401, which effectively concentrates the light. This makes the exit angle of a large amount of scattered light more consistent on the microlens 400 and the exit surface of the microlens 400, effectively concentrating the light and improving the light output and light utilization of the LED unit 200.

[0071] Specifically, the material of the microlens 400 includes at least one of transparent photoresist, transparent organic resin, silicon dioxide, silicon nitride, and aluminum oxide, which has a high refractive index and can effectively concentrate and focus light. However, it should be noted that the material of the microlens 400 is only an example and is not intended to limit this application. Transparent materials with a refractive index greater than that of the gas in the cavity 500 are all within the scope of protection of this application.

[0072] Specifically, in some exemplary embodiments, the microlens 400 includes a stacked transparent support layer 402 and a lens body 403. The transparent support layer 402 is located between the lens body 403 and the cavity 500, which can effectively support the lens body 403 and improve the overall structural strength and stability of the microlens 400. The transparent support layer 402 has a structure that is recessed towards the LED unit 200, and the light-concentrating convex surface 401 is located on the side of the transparent support layer 402 away from the lens body 403. Therefore, during the manufacturing process, the transparent support layer 402 can serve as a pre-shaped structure for the light-concentrating convex surface 401 and also as a support structure for the lens body 403, which is beneficial to improving the manufacturing accuracy and structural reliability.

[0073] The transparent support layer 402 may be made of the same material as or different from the lens body 403, but the refractive index of both the transparent support layer 402 and the lens body 403 is greater than the refractive index of the cavity 500. In some optional embodiments, the transparent support layer 402 is made of inorganic oxide. In some preferred embodiments, the transparent support layer 402 is made of at least one of silicon dioxide and aluminum oxide, which has good light transmittance and good support.

[0074] In some exemplary embodiments, the thickness of the transparent support layer 402 in the region away from the grid structure 300 is greater than or equal to the thickness of the transparent support layer 402 in the region close to the grid structure 300, so as to pre-form a convex lens shape; in other exemplary embodiments, the transparent support layer 402 is a thin coating.

[0075] Specifically, the ratio between the radius of curvature of the focusing convex surface 401 and the lateral dimension of the light-emitting surface of the LED unit 200 is 0.15 to 18. The light-emitting surface refers to the side of the LED unit 200 that emits divergent light away from the driving panel 100, or the side of the LED unit 200 that emits divergent light towards the cavity 500 and the microlens 400. Understandably, the ratio between the radius of curvature of the focusing convex surface 401 and the lateral dimension of the light-emitting surface of the LED unit 200 can be any value between 0.15 and 18. For example, the ratio between the radius of curvature of the focusing convex surface 401 and the lateral dimension of the light-emitting surface of the LED unit 200 can be 0.15, 0.5, 1, 2, 5, 10, 15, 18, etc. In this way, the focusing convex surface 401 can refract light at a larger angle, effectively reducing the focal length and facilitating the collimation of the divergent light emitted by the LED unit 200.

[0076] In some exemplary embodiments, the ratio between the radius of curvature of the focusing convex surface 401 and the lateral dimension of the light-emitting surface of the LED unit 200 is 0.15 to 5, which makes the microlens 400 have a larger refraction angle and effectively reduce the focal length; in some preferred embodiments, the ratio between the radius of curvature of the focusing convex surface 401 and the lateral dimension of the light-emitting surface of the LED unit 200 is 0.3 to 3, which results in a better focusing effect.

[0077] In some exemplary embodiments, the radius of curvature of the focusing convex surface 401 is 1.5 μm to 50 μm; it can be understood that the radius of curvature of the focusing convex surface 401 can be any value from 1.5 μm to 50 μm; exemplaryly, the radius of curvature of the focusing convex surface 401 can be 1.5 μm, 2 μm, 5 μm, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, 45 μm, 50 μm, etc.

[0078] In some exemplary embodiments, the lateral dimension of the light-emitting surface of the LED unit 200 is 3μm to 100μm; it can be understood that the lateral dimension of the light-emitting surface of the LED unit 200 can be any value from 3μm to 100μm; exemplaryly, the lateral dimension of the light-emitting surface of the LED unit 200 can be 3μm, 5μm, 10μm, 20μm, 25μm, 30μm, 50μm, 70μm, 80μm, 90μm, 100μm, etc.

[0079] In this way, the radius of curvature of the focusing convex surface 401 can be matched with the lateral dimensions of the light-emitting surface of different LED units 200, and work together to effectively improve the collimation of the scattered light emitted by the backlight of the LED unit 200, greatly improve the light output of the LED unit 200 and the subsequent light utilization rate, and has good applicability.

[0080] Specifically, the light-emitting surface of the LED unit 200 is located at the focal plane of the microlens 400. The distance between the focusing convex surface 401 and the light-emitting surface of the LED unit 200 is positively correlated with the focal length of the microlens 400, and this distance is also positively correlated with the refractive index of the microlens 400 material. However, the focal length of the microlens 400 is negatively correlated with the refractive index of the microlens 400 material; that is, the larger the refractive index of the microlens 400 material, the smaller the focal length of the microlens 400. The focal length of the microlens 400 is also related to the radius of curvature of the focusing convex surface 401. By adjusting the radius of curvature of the focusing convex surface 401 and selecting the refractive index of the microlens 400 material, in conjunction with adjusting the distance, the light-emitting surface of the LED unit 200 is located at the focal plane of the microlens 400. This synergistically improves the effectiveness, reliability, and stability of the collimation of the divergent light emitted by the LED unit 200 by the microlens 400, greatly enhancing the luminous brightness of the LED unit 200.

[0081] Specifically, such as Figure 1 As shown, the Micro LED chip also includes a color conversion layer 600, which covers the side of the microlens 400 away from the LED unit 200. The color conversion layer 600 is used to convert the color of the light emitted by the LED unit 200, so that different areas in the Micro LED chip can emit different colors of light to achieve full-color display. More importantly, the color conversion layer 600 and the LED unit 200 are pre-collimated by the microlens 400, so that more of the light emitted by the LED unit 200 can be incident on the color conversion layer 600 and utilized by the color conversion layer 600, which greatly improves the color conversion efficiency.

[0082] In some exemplary embodiments, the side surface of the microlens 400 facing away from the LED unit 200 may be higher than the grid structure 300; in other exemplary embodiments, the side surface of the microlens 400 facing away from the LED unit 200 may be flush with the upper surface of the grid structure 300; in some preferred embodiments, the side surface of the microlens 400 facing away from the LED unit 200 is located within the grid aperture 301, that is, the height of the upper surface of the microlens 400 is less than the height of the grid structure 300, so as to facilitate the deposition of the color conversion layer 600 on the microlens 400, and the height of the side surface of the color conversion layer 600 facing away from the LED unit 200 may be higher than, equal to or less than the height of the grid structure, which is not specifically limited in this application.

[0083] The color conversion layer 600 uses a color conversion material, which includes organic resin and inorganic nanoparticles. The organic resin serves as a carrier, and the inorganic nanoparticles, such as quantum dots, are used to achieve photoluminescence.

[0084] In some exemplary embodiments, the color conversion layer 600 includes a blue light conversion area, a red light conversion area, and a green light conversion area disposed on the same layer. Light emitted from the side of the microlens 400 away from the LED unit 200 to the color conversion layer 600 can emit different colors of light after passing through different color conversion areas. After passing through the blue light conversion area, blue light is emitted; after passing through the red light conversion area, red light is emitted; and after passing through the green light conversion area, green light is emitted, so as to realize the multi-color full-color display of the Micro LED chip.

[0085] Specifically, the cavity 500 can also be reused as a heat insulation layer between the LED unit 200 and the color conversion layer 600. Compared with the structure in traditional Micro LED chips where the light-emitting surface of the LED unit 200 is in direct contact with the color conversion material of the color conversion layer 600, the cavity 500 can effectively isolate the strong light intensity of the LED unit 200, greatly reduce the blue light heat conduction of the LED unit 200, and increase the aging threshold of the microlens 400 and the color conversion layer 600 materials. In particular, the material of the color conversion layer 600 includes quantum dots, which are extremely prone to aging under high temperature conditions. The cavity 500 can effectively slow down the aging of the color conversion layer 600. Moreover, the microlens 400 is located between the cavity 500 and the color conversion layer 600, which can further play a role in separating the two, greatly reducing the aging rate of the color conversion layer 600. This is beneficial to improving the overall stability and long-term performance of the Micro LED chip and extending its lifespan.

[0086] Please refer to the appendix of the instruction manual below. Figure 1 , 3 -8. This application introduces a method for fabricating a Micro LED chip.

[0087] First, such as Figure 3-4As shown, a driving panel is provided; the driving panel is provided with a grid structure and multiple LED units arranged in an array, the grid structure surrounding the multiple LED units to form multiple grid holes arranged in an array.

[0088] like Figure 3 and Figure 4 As shown, the grid structure 300 can be formed after the LED unit 200, that is, multiple LED units 200 are formed on the driving panel 100, and then the grid structure 300 is formed around the multiple LED units 200, so that the multiple LED units 200 are respectively located in the grid holes 301 of the grid structure 300.

[0089] In some exemplary embodiments, after forming a plurality of LED units 200, a whole layer of grid material can be formed on the driving panel 100 having a plurality of LED units 200, and then the grid material layer is etched to form a grid structure 300 having a plurality of grid holes 301.

[0090] like Figure 4 As shown, in some exemplary embodiments, after the grid structure 300 is formed, a reflective layer 700 is formed on the driving panel 100 having the grid structure 300. The reflective layer 700 at least covers the sidewalls of the grid hole 301. During the formation of the reflective layer 700, a whole layer of reflective material can be formed on the driving panel 100 having the grid structure 300. The reflective material layer covers the grid hole 301 (and the LED unit 200) and the grid structure 300. It can be formed by deposition by atomic layer deposition, chemical vapor deposition, evaporation, sputtering, etc. Then, the reflective material layer is etched to remove the reflective material covering the LED unit 200 inside the grid hole 301, and retain the reflective material on the sidewall of the grid hole 301, or retain the reflective material on the sidewall of the grid hole 301 and the surface of the grid structure 300 facing away from the driving panel 100, thus forming the reflective layer 700.

[0091] Next, as Figure 5-8 As shown, multiple microlenses are formed on the driving panel; the microlenses are disposed in the grid holes, and the surface facing the LED unit is a light-concentrating convex surface. The light emitted by the LED unit can pass through the light-concentrating convex surface and then exit from the side of the microlens away from the LED unit.

[0092] Specifically, in some exemplary embodiments, a cavity exists between the microlens and the LED unit; correspondingly, forming a plurality of microlenses on the driving panel includes:

[0093] A sacrificial layer is formed in the grid holes; the sacrificial layer covers the LED unit, and the surface of the sacrificial layer is a concave surface recessed towards the LED unit;

[0094] The microlens is formed on the sacrificial layer, and the sacrificial layer is removed to form the cavity between the microlens and the LED unit.

[0095] Among them, such as Figure 5 As shown, the sacrificial layer 510 is a precursor layer for forming the microlens 400. It can fill the grid holes 301 and cover the LED unit 200. The formation process of the sacrificial layer 510 includes at least one of high-speed spin coating and nanoimprinting to efficiently and accurately form a concave surface facing the LED unit 200. This concave surface is used to form the microlens 400, that is, the concave surface is used to form the light-concentrating convex surface 401, which is beneficial to improve the preparation accuracy and preparation yield of the light-concentrating convex surface 401. Furthermore, the radius of curvature of the concave surface can be determined by adjusting the process parameters of the sacrificial layer 510 formation process, resulting in high preparation accuracy and good reliability.

[0096] Specifically, the concave surface of the light-concentrating convex surface 401 and the concave surface of the sacrificial layer 510 are configured to conform to each other. That is, the radius of curvature of the light-concentrating convex surface 401 is the same as that of the concave surface of the sacrificial layer 510. After the concave surface of the sacrificial layer 510 is formed, the shape of the light-concentrating curved surface is also determined. The radius of curvature of the light-concentrating convex surface 401 can also be determined based on the process parameters of the process of forming the sacrificial layer 510, which is beneficial to improving the preparation accuracy of the light-concentrating curved surface.

[0097] In some exemplary embodiments, the material of the sacrificial layer 510 includes a resin material, which has good molding controllability and is beneficial to improving the accuracy and reliability of the concave shape of the sacrificial layer 510.

[0098] Specifically, the microlens 400 includes a transparent support layer 402 and a lens body 403; the process of forming the microlens on the sacrificial layer and removing the sacrificial layer to form the cavity between the microlens and the LED unit includes:

[0099] The transparent support layer is formed on the sacrificial layer; the transparent support layer has a structure that is recessed toward the LED unit.

[0100] Remove the sacrificial layer to form the cavity between the transparent support layer and the LED unit;

[0101] The lens body is formed on the transparent support layer to obtain the microlens.

[0102] Among them, such as Figure 6As shown, a transparent support layer 402 is formed on the sacrificial layer 510. The transparent support layer 402 can be a thin coating, so that the transparent support layer 402 as a whole presents a structure that is recessed towards the LED unit 200. On the one hand, the surface shape of the transparent support layer 402 facing the LED unit 200 has been determined, that is, the radius of curvature of the light-concentrating convex surface 401 has been predetermined, which improves the morphological accuracy and reliability of the light-concentrating convex surface 401. On the other hand, the transparent support layer 402 can serve as a support structure, providing good support for the subsequent formation of the lens body 403, avoiding the occurrence of structural collapse, and greatly improving the fabrication yield and fabrication reliability.

[0103] like Figure 7 As shown, the sacrificial layer 510 can be directly removed after the transparent support layer 402 is formed without affecting the subsequent formation of the transparent body. The removal process of the sacrificial layer 510 includes at least one of thermal decomposition, hydrolysis and plasma etching. The etching selectivity of the sacrificial layer 510 material is much higher than that of the microlens 400 material, so as to effectively remove the sacrificial layer 510 while avoiding damage to the morphological accuracy of the microlens 400, thereby improving the preparation accuracy and preparation yield of the entire preparation method.

[0104] Then, as Figure 8 As shown, a lens body 403 is formed on a transparent support layer 402 after the sacrificial layer 510 has been removed. The lens body 403 can be filled onto the transparent support layer 402 by spin coating, and together with the transparent support layer 402, it constitutes a complete microlens 400. The refractive index of the microlens 400 is determined based on the material of the microlens 400. Correspondingly, the refractive index of the transparent support layer 402 is determined based on the material of the transparent support layer 402, and the refractive index of the lens body 403 is determined based on the material of the lens body 403.

[0105] Furthermore, in some exemplary embodiments, both the lens body 403 and the sacrificial layer 510 can be made of resin material, while the transparent support layer 402 can be made of inorganic oxide. Thus, removing the sacrificial layer 510 before forming the lens body 403 can effectively avoid damage to the lens body 403. At the same time, the etching selectivity of the resin material of the sacrificial layer 510 is much greater than that of the inorganic oxide material of the transparent support layer 402, and the transparent support layer 402 will not be damaged. This fabrication method can effectively reduce the damage to the microlens 400 as a whole during the fabrication process, greatly improve the morphological accuracy and reliability of the microlens 400 and the focusing convex surface 401, and is conducive to improving the fabrication accuracy and yield, and improving the overall performance of the Micro LED chip.

[0106] Specifically, such as Figure 1 As shown, after forming multiple microlenses on the drive panel, the method further includes:

[0107] A color conversion layer is formed on the side of the microlens opposite to the LED unit.

[0108] The color conversion layer 600 is used to convert the color of the light emitted by the LED unit 200. Accordingly, the materials of different color conversion areas in the color conversion layer 600 are also different. When the color conversion area is the same color as the light emitted by the LED unit 200, the material of the color conversion area can be transparent adhesive. When the color conversion area is different from the light emitted by the LED unit 200, the material of the color conversion area can be a mixture of quantum dots of the target color light and photoresist to form quantum dot adhesive of the target color light, which is filled on the surface of the microlens 400 above the LED unit 200 to form the color conversion area of ​​the target color light. For example, if the light emitted by the LED unit 200 itself is blue light, the material of the blue light color conversion area does not need to be a blue light color conversion material, and transparent adhesive can be filled in the blue light color conversion area. The material of the red light color conversion area can be red quantum dot adhesive, and the material of the green light color conversion area can be green quantum dot adhesive to improve the full-color display quality of the Micro LED chip.

[0109] Furthermore, the color conversion layer 600 is formed after the cavity 500 and microlens 400 are formed, and it is also separated from the LED unit 200 by the cavity 500 and microlens 400. This can effectively avoid the adverse effects of high temperature conditions during the fabrication process on the color conversion layer 600 material, improve the aging threshold of the color conversion layer 600 material, and benefit the efficiency, stability and long-term performance of Micro LED chip full-color display.

[0110] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0111] The above description is merely some embodiments of this application and is not intended to limit this application. Those skilled in the art should understand that various changes and improvements may be made to this application, and any modifications, equivalent substitutions and improvements made in accordance with this application fall within the scope of protection claimed by this application.

Claims

1. A Micro LED chip, characterized in that, include: Driver panel; Multiple LED units are arranged in an array on the drive panel; A grid structure, comprising multiple grid holes arranged in an array around multiple LED units; Multiple microlenses are disposed in the grid holes, and the surface facing the LED unit is a light-concentrating convex surface. There is a cavity between the microlenses and the LED unit. The light-emitting surface of the LED unit is located at the focal plane of the microlenses. The light emitted by the LED unit can pass through the cavity and the light-concentrating convex surface and then exit from the side of the microlenses away from the LED unit. A color conversion layer covers the side of the microlens facing away from the LED unit; the cavity can be reused as a heat insulation layer between the LED unit and the color conversion layer.

2. The Micro LED chip according to claim 1, characterized in that, The refractive index of the microlens is greater than that of the cavity.

3. The Micro LED chip according to claim 1, characterized in that, The microlens is used to focus and / or collimate the light emitted from the LED unit into the cavity.

4. The Micro LED chip according to claim 1, characterized in that, The ratio between the radius of curvature of the light-concentrating convex surface and the lateral dimension of the light-emitting surface of the LED unit is 0.15 to 18.

5. The Micro LED chip according to claim 1, characterized in that, The microlens includes a stacked transparent support layer and a lens body. The transparent support layer is located between the lens body and the cavity. The transparent support layer has a recessed structure facing the LED unit. The light-concentrating convex surface is located on the side of the transparent support layer away from the lens body.

6. The Micro LED chip according to claim 1, characterized in that, The lateral dimension of the grid aperture gradually increases from the side closer to the LED unit to the side farther away from the LED unit.

7. The Micro LED chip according to claim 1, characterized in that, The Micro LED chip also includes a reflective layer, which at least covers the sidewalls of the grid aperture.

8. The Micro LED chip according to claim 1, characterized in that, The material of the microlens includes at least one of transparent photoresist, transparent organic resin, silicon dioxide, silicon nitride, and aluminum oxide.

9. A method for fabricating a Micro LED chip, characterized in that, include: Provides a driver panel; The drive panel is provided with a grid structure and multiple LED units arranged in an array. The grid structure surrounds the multiple LED units to form multiple grid holes arranged in an array. A sacrificial layer is formed in the grid holes; The sacrificial layer covers the LED unit, and the surface of the sacrificial layer is a concave surface recessed towards the LED unit; A microlens is formed on the sacrificial layer, and the sacrificial layer is removed to form a cavity between the microlens and the LED unit; the microlens is disposed in the grid hole, and the surface facing the LED unit is a light-concentrating convex surface, so that the light emitted by the LED unit can pass through the light-concentrating convex surface and exit from the side of the microlens away from the LED unit. A color conversion layer is formed on the side of the microlens opposite to the LED unit.

10. The method for fabricating a Micro LED chip according to claim 9, characterized in that, The microlens includes a transparent support layer and a lens body; forming the microlens on the sacrificial layer and removing the sacrificial layer to form the cavity between the microlens and the LED unit includes: The transparent support layer is formed on the sacrificial layer; the transparent support layer has a structure that is recessed toward the LED unit. Remove the sacrificial layer to form the cavity between the transparent support layer and the LED unit; The lens body is formed on the transparent support layer to obtain the microlens.

11. The method for fabricating a Micro LED chip according to claim 9, characterized in that, The light-concentrating convex surface and the concave surface of the sacrificial layer are conformally arranged.

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