A miniature light-emitting diode and its manufacturing method

Abstract

This application provides a micro light-emitting diode and its manufacturing method. A first reflective layer, a first light-emitting structure, a transparent substrate, a second reflective layer, a second light-emitting structure, a third reflective layer, and a third light-emitting structure are sequentially stacked. The transparent substrate has a frustum or truncated cone structure. The transparent substrate has a first surface, a second surface, and inclined sidewalls. The area of ​​the first surface is larger than the area of ​​the second surface. The first light-emitting structure emits light using the inclined sidewalls. A first electrode is located on the surface of the first reflective layer away from the first light-emitting structure. A second electrode penetrates the first reflective layer and at least a portion of the first light-emitting structure. A third electrode penetrates the third light-emitting structure to the third reflective layer. A fourth electrode is located on the surface of the third light-emitting structure away from the third reflective layer. The first, second, and third light-emitting structures emit light in the same direction, avoiding side color mixing effects from light-emitting structures on the same plane and improving display performance.

Description

Technical Field

[0001] This invention relates to the field of semiconductor devices, and in particular to a miniature light-emitting diode and its manufacturing method. Background Technology

[0002] With the rapid development of terminal devices, higher demands are being placed on their displays. Current display technology is mainly divided into liquid crystal displays (LCDs), organic light-emitting diodes (OLEDs), and micro-light-emitting diode (Micro-LED) displays. Micro-LED displays are a new generation of display technology that miniaturizes, thins, and arrays diode structures, enabling single-point driving light emission and offering advantages such as high brightness, high luminous efficiency, and low power consumption. Micro-LEDs are micrometers in size, and the spacing between each Micro-LED is also at the micrometer level; therefore, Micro-LED-based display panels contain a massive number of Micro-LEDs.

[0003] However, due to the small spacing between each Micro-LED, color mixing occurs when different Micro-LEDs emit light, resulting in a deterioration in display quality. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a micro light-emitting diode and a method for manufacturing the same, which reduces the impact of color mixing, improves the display effect, and reduces the process cost.

[0005] To achieve the above objectives, this application provides the following technical solution:

[0006] This application provides a miniature light-emitting diode, including:

[0007] A first reflective layer, a first light-emitting structure, a transparent substrate, a second reflective layer, a second light-emitting structure, a third reflective layer, and a third light-emitting structure are sequentially stacked.

[0008] The transparent substrate has a frustum or truncated cone structure. The transparent substrate has a first surface in contact with the first light-emitting structure, a second surface in contact with the second light-emitting structure, and an inclined sidewall. The area of ​​the first surface is larger than the area of ​​the second surface. The first light-emitting structure emits light using the inclined sidewall.

[0009] The first electrode is located on the surface of the first reflective layer away from the first light-emitting structure.

[0010] The second electrode penetrates the first reflective layer and at least a portion of the first light-emitting structure;

[0011] The third electrode extends through the third light-emitting structure to the third reflective layer;

[0012] The fourth electrode is located on the surface of the third light-emitting structure away from the third reflective layer.

[0013] Optionally, the light emission efficiency of the first light-emitting structure is determined based on the thickness of the transparent substrate and the ratio of the first surface to the second surface.

[0014] Optionally, the thickness of the transparent substrate ranges from 50 to 120 micrometers, and the ratio of the first surface to the second surface ranges from [1, 2].

[0015] Optionally, the second light-emitting structure and the third light-emitting structure are electrically connected through the third reflective layer.

[0016] Optionally, the reflectivity of the third reflective layer to the second light-emitting structure is less than a first threshold, and the reflectivity of the third reflective layer to the third light-emitting structure is greater than a second threshold.

[0017] Optionally, the transparent substrate is made of sapphire or gallium nitride.

[0018] Optionally, if the transparent substrate is made of sapphire, the transparent substrate has conductive contacts that electrically connect the second reflective layer and the first light-emitting structure.

[0019] Optionally, the first light-emitting structure is a blue light-emitting structure, the second light-emitting structure is a red light-emitting structure, and the third light-emitting structure is a green light-emitting structure.

[0020] Optionally, the blue light emitting structure includes a second type of blue light conductive layer, a blue light emitting layer and a first type of blue light conductive layer stacked sequentially; the red light emitting structure includes a first type of red light conductive layer, a red light emitting layer and a second type of red light conductive layer stacked sequentially; and the green light emitting structure includes a second type of green light conductive layer, a green light emitting layer and a first type of green light conductive layer stacked sequentially.

[0021] Optionally, it further includes an insulating layer for isolating the third electrode and the third light-emitting structure, as well as the first electrode and the first reflective layer.

[0022] This application provides a method for manufacturing a miniature light-emitting diode, comprising:

[0023] A first light-emitting structure is formed on a transparent substrate, a second light-emitting structure is formed on the first substrate, and a third light-emitting structure is formed on the second substrate;

[0024] A third reflective layer is formed on the surface of the third light-emitting structure, and a first reflective layer is formed on the surface of the first light-emitting structure;

[0025] The second light-emitting structure and the third light-emitting structure are bonded together with the third reflective layer facing the second light-emitting structure.

[0026] The second light-emitting structure and the first substrate are stripped apart, and a second reflective layer is formed on the exposed surface of the second light-emitting structure.

[0027] The transparent substrate is cut to form a frustum structure or a truncated cone structure. The transparent substrate has a first surface in contact with the first light-emitting structure, a second surface away from the first light-emitting structure, and inclined sidewalls. The area of ​​the first surface is larger than the area of ​​the second surface.

[0028] The second light-emitting structure and the first light-emitting structure are bonded together with the second reflective layer facing the second surface;

[0029] The third light-emitting structure and the second substrate are stripped apart;

[0030] A first electrode, a second electrode, a third electrode, and a fourth electrode are formed. The first electrode is located on the side surface of the first reflective layer away from the first light-emitting structure. The second electrode penetrates the first reflective layer and at least part of the first light-emitting structure. The third electrode penetrates the third light-emitting structure to the third reflective layer. The fourth electrode is located on the side surface of the third light-emitting structure away from the third reflective layer.

[0031] This application provides a miniature light-emitting diode, comprising a first reflective layer, a first light-emitting structure, a transparent substrate, a second reflective layer, a second light-emitting structure, a third reflective layer, and a third light-emitting structure stacked sequentially. The transparent substrate is a frustum or truncated cone structure, and has a first surface in contact with the first light-emitting structure, a second surface in contact with the second light-emitting structure, and inclined sidewalls. The area of ​​the first surface is larger than the area of ​​the second surface. The first light-emitting structure emits light using the inclined sidewalls. A first electrode is located on the side surface of the first reflective layer away from the first light-emitting structure. A second electrode penetrates the first reflective layer and at least part of the first light-emitting structure. A third electrode penetrates the third light-emitting structure to the third reflective layer. A fourth electrode is located on the side surface of the third light-emitting structure away from the third reflective layer. In other words, by stacking the first, second, and third light-emitting structures sequentially to form a vertical structure, the light emitted by the first light-emitting structure is reflected by the first reflective layer and exits through the inclined sidewall of the transparent substrate. The light emitted by the second light-emitting structure is reflected by the second reflective layer and exits through the third light-emitting structure. The light emitted by the third light-emitting structure is reflected by the third reflective layer. That is, the light emission directions of the first, second, and third light-emitting structures are all facing the same side, avoiding the side color mixing effect of light-emitting structures on the same plane. Furthermore, by using four electrodes to control the light emission of the three light-emitting structures respectively, the display effect can be improved and the process cost can be reduced. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This paper shows a schematic diagram of the structure of a miniature light-emitting diode provided in an embodiment of this application;

[0034] Figure 2 This invention provides a schematic diagram of the structure of another miniature light-emitting diode according to an embodiment of the present application.

[0035] Figure 3 A schematic flowchart of a method for manufacturing a miniature light-emitting diode according to an embodiment of this application is shown;

[0036] Figures 4-10 A schematic diagram of a micro light-emitting diode manufactured according to the manufacturing method provided in the embodiments of this application is shown. Detailed Implementation

[0037] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0038] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0039] Secondly, this application provides a detailed description in conjunction with schematic diagrams. When detailing the embodiments of this application, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of this application. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0040] Current display technology is mainly divided into liquid crystal displays (LCDs), organic light-emitting diode displays (OLEDs), and micro-light-emitting diode (Micro-LED) displays. Micro-LED displays are a next-generation display technology that miniaturizes, thins, and arrays diode structures, enabling single-point light emission and offering advantages such as high brightness, high luminous efficiency, and low power consumption. Micro-LEDs are micrometers in size, and the spacing between each Micro-LED is also at the micrometer level; therefore, Micro-LED-based display panels contain a massive number of Micro-LEDs.

[0041] However, due to the small spacing between each Micro-LED, color mixing occurs when different Micro-LEDs emit light, resulting in a deterioration in display quality. Furthermore, the current manufacturing process for display panels based on micro-LEDs is extremely complex, requiring the transfer of a massive number of tiny Micro-LEDs into a large-size panel, leading to lower yield rates and increased costs.

[0042] Based on the above technical problems, this application provides a micro light-emitting diode, comprising a first reflective layer, a first light-emitting structure, a transparent substrate, a second reflective layer, a second light-emitting structure, a third reflective layer, and a third light-emitting structure stacked sequentially. The transparent substrate is a frustum or truncated cone structure, and has a first surface in contact with the first light-emitting structure, a second surface in contact with the second light-emitting structure, and inclined sidewalls. The area of ​​the first surface is larger than the area of ​​the second surface. The first light-emitting structure emits light using the inclined sidewalls. A first electrode is located on the side surface of the first reflective layer away from the first light-emitting structure. A second electrode penetrates the first reflective layer and at least part of the first light-emitting structure. A third electrode penetrates the third light-emitting structure to the third reflective layer. A fourth electrode is located on the side surface of the third light-emitting structure away from the third reflective layer. In other words, by stacking the first, second, and third light-emitting structures sequentially to form a vertical structure, the light emitted by the first light-emitting structure is reflected by the first reflective layer and exits through the inclined sidewall of the transparent substrate. The light emitted by the second light-emitting structure is reflected by the second reflective layer and exits through the third light-emitting structure. The light emitted by the third light-emitting structure is reflected by the third reflective layer. That is, the light emission directions of the first, second, and third light-emitting structures are all facing the same side, avoiding the side color mixing effect of light-emitting structures on the same plane. Furthermore, by using four electrodes to control the light emission of the three light-emitting structures respectively, the display effect can be improved and the process cost can be reduced.

[0043] To better understand the technical solution and effects of this application, the specific embodiments will be described in detail below with reference to the accompanying drawings.

[0044] refer to Figure 1The diagram shown is a schematic diagram of a micro light-emitting diode provided in an embodiment of this application. The micro light-emitting diode provided in this embodiment includes a first reflective layer 110, a first light-emitting structure 120, a transparent substrate 130, a second reflective layer 140, a second light-emitting structure 150, a third reflective layer 160, and a third light-emitting structure 170, which are stacked sequentially.

[0045] In the embodiments of this application, the first light-emitting structure 120, the second light-emitting structure 150 and the third light-emitting structure 170 are used to emit light. The light emitted by the first light-emitting structure 120, the second light-emitting structure 150 and the third light-emitting structure 170 has different center wavelengths so as to mix the light-emitting colors and perform light-emitting display.

[0046] The light emission colors of the first light-emitting structure 120, the second light-emitting structure 150, and the third light-emitting structure 170 can be set according to the actual situation.

[0047] As an example, the first light-emitting structure 120 is a blue light-emitting structure, the second light-emitting structure 150 is a red light-emitting structure, and the third light-emitting structure 170 is a green light-emitting structure.

[0048] In the embodiments of this application, the first light-emitting structure 120, the second light-emitting structure 150, and the third light-emitting structure 170 each have multiple film layers for emitting light. When the first light-emitting structure 120 is a blue light-emitting structure, the second light-emitting structure 150 is a red light-emitting structure, and the third light-emitting structure 170 is a green light-emitting structure, the blue light-emitting structure includes a second type blue light-conductive layer 121, a blue light-emitting layer 122, and a first type blue light-conductive layer 123 stacked sequentially; the red light-emitting structure includes a first type red light-conductive layer 151, a red light-emitting layer 152, and a second type red light-conductive layer 153 stacked sequentially; and the green light-emitting structure includes a second type green light-conductive layer 171, a green light-emitting layer 172, and a first type green light-conductive layer 173 stacked sequentially. (Refer to...) Figure 2 The diagram shown is a structural schematic of another miniature light-emitting diode provided in an embodiment of this application.

[0049] Specifically, the blue light-emitting layer 122 is used to emit blue light, the red light-emitting layer 152 is used to emit red light, and the green light-emitting layer 172 is used to emit green light. The blue light-emitting layer 122, the red light-emitting layer 152, and the green light-emitting layer 172 can also be called active layers, which can be quantum well layers.

[0050] The second type of blue conductive layer 121 and the first type of blue conductive layer 123 are used to conduct electrical signals to the blue light emitting layer 122, so that the blue light emitting layer 122 emits blue light. The first type of red conductive layer 151 and the second type of red conductive layer 153 are used to conduct electrical signals to the red light emitting layer 152, so that the red light emitting layer 152 emits red light. The second type of green conductive layer 171 and the first type of green conductive layer 173 are used to conduct electrical signals to the green light emitting layer 172, so that the green light emitting layer 172 emits green light.

[0051] Specifically, the second type blue conductive layer 121 and the first type blue conductive layer 123 can be N-type and P-type conductive layers, respectively, or they can be P-type and N-type conductive layers, respectively. Correspondingly, the first type red conductive layer 151 and the second type red conductive layer 153 can be P-type and N-type conductive layers, respectively, or they can be N-type and P-type conductive layers, respectively. Similarly, the second type green conductive layer 171 and the first type green conductive layer 173 can be N-type and P-type conductive layers, respectively, or they can be P-type and N-type conductive layers, respectively. The embodiments in this application are not specifically limited here; specific settings can be made by those skilled in the art according to actual conditions.

[0052] Specifically, the material of the N-type conductive layer can be N-type doped gallium nitride, and the material of the P-type conductive layer can be P-type doped gallium nitride.

[0053] In the embodiments of this application, the first reflective layer 110 is used to reflect the light emitted by the first light-emitting structure 120, that is, the light emitted by the first light-emitting structure 120 is emitted from the same direction, thereby improving the light emission efficiency of the first light-emitting structure 120. Correspondingly, the second reflective layer 140 is used to reflect the light emitted by the second light-emitting structure 150, that is, the light emitted by the second light-emitting structure 150 is emitted from the same direction. The third reflective layer 160 is used to reflect the light emitted by the third light-emitting structure 170, that is, the light emitted by the third light-emitting structure 170 is emitted from the same direction. The light emission directions of the second light-emitting structure 150 and the third light-emitting structure 170 are the same as the emission direction of the first light-emitting structure 120. By stacking the first light-emitting structure 120, the second light-emitting structure 150, and the third light-emitting structure 170 sequentially to form a vertical structure, the side color mixing effect of light-emitting structures on the same plane is avoided, ultimately improving the display effect.

[0054] In practical applications, when the light from the first light-emitting structure 120 is emitted, it passes through multiple film layers such as the second reflective layer 140, the second light-emitting structure 150, the third reflective layer 160, and the third light-emitting structure 170. The light may be lost or even fail to be emitted. Therefore, the transparent substrate 130 can be configured as a frustum or truncated cone structure. The transparent substrate 130 has a first surface 131 that contacts the first light-emitting structure 120, a second surface 132 that contacts the second light-emitting structure 150, and an inclined sidewall 133. The area of ​​the first surface 131 is larger than the area of ​​the second surface 132, so that the area of ​​the first light-emitting structure 120 is larger than the area of ​​the second light-emitting structure 150. Subsequently, the first light-emitting structure 120 can emit light using the inclined sidewall 133, thus avoiding light loss of the first light-emitting structure 120.

[0055] In practical applications, when the first light-emitting structure 120 is a blue light-emitting structure, the second light-emitting structure 150 is a red light-emitting structure, and the third light-emitting structure 170 is a green light-emitting structure, the blue light emitted by the first light-emitting structure 120 will be absorbed by the second light-emitting structure 150. Therefore, the first light-emitting structure 120 uses the inclined sidewall 133 of the transparent substrate 130 to emit blue light, which can prevent the blue light from being absorbed by the second light-emitting structure 150.

[0056] In the embodiments of this application, the light emission efficiency of the first light-emitting structure 120 is related to the area of ​​the inclined sidewall 133, that is, the area of ​​the inclined sidewall 133 can be determined according to the thickness of the transparent substrate 130 and the ratio of the first surface 131 and the second surface 132.

[0057] As an example, the thickness of the transparent substrate 130 ranges from 50 to 120 micrometers, and the ratio of the first surface 131 to the second surface 132 ranges from [1, 2].

[0058] In the embodiments of this application, in order to enable the second light-emitting structure 150 and the third light-emitting structure 170 to emit light from the same side, the third reflective layer 160 can reflect the light emitted by the third light-emitting structure 170 and transmit the light emitted by the second light-emitting structure 150. That is, the reflectivity of the third reflective layer 160 to the second light-emitting structure 150 is less than the first threshold, and the reflectivity of the third reflective layer 160 to the third light-emitting structure 170 is greater than the second threshold.

[0059] Specifically, the first threshold can be 10%, and the second threshold can be 80%. When the first light-emitting structure 120 is a blue light-emitting structure, the second light-emitting structure 150 is a red light-emitting structure, and the third light-emitting structure 170 is a green light-emitting structure, the reflectivity of the third reflective layer 160 to the red light emitted by the second light-emitting structure 150 is less than 10%, and the reflectivity to the green light emitted by the third light-emitting structure 170 is greater than 80%.

[0060] In embodiments of this application, the micro light-emitting diode includes a first electrode 181, a second electrode 182, a third electrode 183, and a fourth electrode 184. The second electrode 182 is located on the side surface of the first reflective layer 110 away from the first light-emitting structure 120. The first electrode 181 penetrates the first reflective layer 110 and at least a portion of the first light-emitting structure 120. The third electrode 183 penetrates the third light-emitting structure 170 to the third reflective layer 160. The fourth electrode 184 is located on the side surface of the third light-emitting structure 170 away from the third reflective layer 160.

[0061] In other words, the first electrode 181 and the second electrode 182 are located on one side of the micro light-emitting diode, and the third electrode 183 and the fourth electrode 184 are located on the other side of the micro light-emitting diode. The first electrode 181, the second electrode 182, the third electrode 183 and the fourth electrode 184 are used to control the first light-emitting structure 120, the second light-emitting structure 150 and the third light-emitting structure 170 to emit light, so as to realize the control and mixing of multiple light-emitting colors.

[0062] In the embodiments of this application, the first reflective layer 110, the second reflective layer 140, and the third reflective layer 160 may all be conductive, and the second light-emitting structure 150 and the third light-emitting structure 170 may be electrically connected through the third reflective layer 160. If the third reflective layer 160 is not conductive, a metal contact may be provided in the third reflective layer 160 so that the second light-emitting structure 150 and the third light-emitting structure 170 may be electrically connected through the metal contact.

[0063] Specifically, the third reflective layer 160 can be a distributed Bragg reflection (DBR) with conductive function.

[0064] In the embodiments of this application, the transparent substrate 130 is made of sapphire or gallium nitride. If the transparent substrate 130 is made of gallium nitride, the first light-emitting structure 120 and the second light-emitting structure 150 can be electrically connected through the conductive transparent substrate 130 and the second reflective layer 140.

[0065] If the transparent substrate 130 is made of sapphire, the transparent substrate 130 may have conductive contacts 134. (Refer to...) Figure 2 As shown, conductive contact 134 electrically connects the second reflective layer 140 and the first light-emitting structure 120, thereby realizing the electrical connection between the first light-emitting structure 120 and the second light-emitting structure 150.

[0066] In practical applications, the thickness of the transparent substrate 130 cannot be too thick. If it is too thick, the distance between the conductive contacts 134 will be too long, which is not conducive to the electrical connection between the first light-emitting structure 120 and the second light-emitting structure 150. The thickness of the transparent substrate 130 cannot be too thin either. If it is too thin, the distance between the blue light-emitting layer 122 and the second reflective layer 140 of the first light-emitting structure 120 will be too close, which will affect the light emission of the first light-emitting structure 120.

[0067] In the embodiments of this application, when the first light-emitting structure 120 is a blue light-emitting structure, the second light-emitting structure 150 is a red light-emitting structure, and the third light-emitting structure 170 is a green light-emitting structure, the first electrode 181 penetrates the first reflective layer 110, the second type blue light-conducting layer 121, the blue light-emitting layer 122 to the first type blue light-conducting layer 123. (Refer to...) Figure 2 As shown.

[0068] Specifically, the first electrode 181 and the second electrode 182 are used to control the first light-emitting structure 120 to emit light, the first electrode 181 and the third electrode 183 are used to control the second light-emitting structure 150 to emit light, and the third electrode 183 and the fourth electrode 184 are used to control the third light-emitting structure 170 to emit light.

[0069] In embodiments of this application, the miniature light-emitting diode may further include an insulating layer 190, as referenced. Figure 2 As shown, the insulating layer 190 is located between the sidewall of the first light-emitting structure 120 and the sidewall of the first electrode 181, and between the sidewall of the third light-emitting structure 170 and the sidewall of the third electrode 183. The insulating layer 190 is used to isolate the third electrode 183 and the third light-emitting structure 170, and also to isolate the first electrode 181 and the first reflective layer 110, as well as to isolate the first electrode 181 and part of the first light-emitting structure 120.

[0070] Therefore, the micro light-emitting diode provided in this application embodiment forms a vertical structure by sequentially stacking a first light-emitting structure, a second light-emitting structure, and a third light-emitting structure. The light emitted by the first light-emitting structure is reflected by the first reflective layer and exits through the inclined sidewall of the transparent substrate. The light emitted by the second light-emitting structure is reflected by the second reflective layer and exits through the third light-emitting structure. The light emitted by the third light-emitting structure is reflected by the third reflective layer. That is, the light-emitting directions of the first, second, and third light-emitting structures are all facing the same side, which can avoid light absorption and achieve effective light emission. It also avoids the side color mixing effect of light-emitting structures on the same plane. Furthermore, by using four electrodes to control the light emission of the three light-emitting structures respectively, multiple light emission control and color mixing can be achieved, which can improve the display effect. In addition, the design of the three-dimensional vertical light-emitting structure can reduce the size of a single pixel unit, improve the display resolution, and eliminate the need to transfer multiple colors of micro light-emitting diodes multiple times. Only the micro light-emitting diode provided in this application embodiment needs to be transferred once, which improves the reliability of the mass transfer process and reduces the process cost.

[0071] This application provides a miniature light-emitting diode, comprising a first reflective layer, a first light-emitting structure, a transparent substrate, a second reflective layer, a second light-emitting structure, a third reflective layer, and a third light-emitting structure stacked sequentially. The transparent substrate is a frustum or truncated cone structure, and has a first surface in contact with the first light-emitting structure, a second surface in contact with the second light-emitting structure, and inclined sidewalls. The area of ​​the first surface is larger than the area of ​​the second surface. The first light-emitting structure emits light using the inclined sidewalls. A first electrode is located on the side surface of the first reflective layer away from the first light-emitting structure. A second electrode penetrates the first reflective layer and at least part of the first light-emitting structure. A third electrode penetrates the third light-emitting structure to the third reflective layer. A fourth electrode is located on the side surface of the third light-emitting structure away from the third reflective layer. In other words, by stacking the first, second, and third light-emitting structures sequentially to form a vertical structure, the light emitted by the first light-emitting structure is reflected by the first reflective layer and exits through the inclined sidewall of the transparent substrate. The light emitted by the second light-emitting structure is reflected by the second reflective layer and exits through the third light-emitting structure. The light emitted by the third light-emitting structure is reflected by the third reflective layer. That is, the light emission directions of the first, second, and third light-emitting structures are all facing the same side, avoiding the side color mixing effect of light-emitting structures on the same plane. Furthermore, by using four electrodes to control the light emission of the three light-emitting structures respectively, the display effect can be improved and the process cost can be reduced.

[0072] Based on the miniature light-emitting diodes provided in the above embodiments, this application also provides a method for manufacturing a miniature light-emitting diode, see reference. Figure 3The diagram shown is a flowchart of a method for manufacturing a miniature light-emitting diode according to an embodiment of this application. The method includes the following steps:

[0073] S101, a first light-emitting structure 120 is formed on a transparent substrate 130, a second light-emitting structure 150 is formed on a first substrate 101, and a third light-emitting structure 170 is formed on a second substrate 102. (Reference) Figure 4 As shown.

[0074] In the embodiments of this application, a first light-emitting structure 120 may be formed on a transparent substrate 130, a second light-emitting structure 150 may be formed on a temporary substrate, such as a first substrate 101, and a third light-emitting structure 170 may be formed on a temporary substrate, such as a second substrate 102.

[0075] Specifically, the first light-emitting structure 120, the second light-emitting structure 150, and the third light-emitting structure 170 can be formed using epitaxial processes.

[0076] Specifically, a first type of blue light conductive layer 123, a blue light emitting layer 122, and a second type of blue light conductive layer 121 can be sequentially epitaxially formed on a transparent substrate 130. (Refer to...) Figure 4 As shown in Figure 4A, a first type of red light conductive layer 151, a red light emitting layer 152, and a second type of red light conductive layer 153 are sequentially epitaxially formed on the first substrate 101. (Refer to Figure 4A) Figure 4 As shown in 4B, a first type of green light-conducting layer 173, a green light-emitting layer 172, and a second type of green light-conducting layer 171 are sequentially epitaxially formed on the second substrate 102. (Refer to...) Figure 4 As shown in 4C.

[0077] S102, a third reflective layer 160 is formed on the surface of the third light-emitting structure 170, and a first reflective layer 110 is formed on the surface of the first light-emitting structure 120, for reference. Figure 5 As shown.

[0078] In the embodiments of this application, after the first light-emitting structure 120 and the third light-emitting structure 170 are epitaxially formed respectively, a third reflective layer 160 can be formed on the surface of the third light-emitting structure 170, and a first reflective layer 110 can be formed on the surface of the first light-emitting structure 120.

[0079] Specifically, a first reflective layer 110 can be formed on the second type of blue light conductive layer 121, as shown in the reference. Figure 5 As shown in Figure 5A, a third reflective layer 160 is formed on the second type green light conductive layer 171, as referenced. Figure 5 As shown in 5B.

[0080] S103, with the third reflective layer 160 facing the second light-emitting structure 150, the second light-emitting structure 150 and the third light-emitting structure 170 are bonded together, with reference to... Figure 6 As shown.

[0081] In the embodiments of this application, after the third reflective layer 160 is formed on the second type green light conductive layer 171, the second light-emitting structure 150 and the third light-emitting structure 170 can be bonded with the third reflective layer 160 facing the second light-emitting structure 150.

[0082] Specifically, the third reflective layer 160 and the second type of red light conductive layer 153 can be bonded together to achieve the bonding of the second light-emitting structure 150 and the third light-emitting structure 170.

[0083] S104, the second light-emitting structure 150 and the first substrate 101 are peeled off, and a second reflective layer 140 is formed on the exposed surface of the second light-emitting structure 150. (Reference) Figure 7 As shown.

[0084] In the embodiments of this application, after bonding the second light-emitting structure 150 and the third light-emitting structure 170, the second light-emitting structure 150 and the first substrate 101 can be peeled off to form a second reflective layer 140 on the exposed surface of the second light-emitting structure 150.

[0085] Specifically, the first substrate 101 and the second light-emitting structure 150 can be peeled off to expose the first type of red light conductive layer 151, and a second reflective layer 140 can be formed on the first type of red light conductive layer 151.

[0086] S105, the transparent substrate 130 is cut to form a frustum structure or a truncated cone structure, reference. Figure 8 As shown.

[0087] In the embodiments of this application, the transparent substrate 130 can be cut to form a frustum structure or a truncated cone structure. The transparent substrate 130 has a first surface 131 that is in contact with the first light-emitting structure 120, a second surface 132 that is away from the first light-emitting structure 120, and an inclined sidewall 133. The area of ​​the first surface 131 is larger than the area of ​​the second surface 132.

[0088] Specifically, the transparent substrate 130 can be cut using a cutting tool to a depth equal to the thickness of the transparent substrate 130, i.e., cutting to the contact surface between the first type of blue light conductive layer 123 and the transparent substrate 130.

[0089] If the transparent substrate 130 is made of sapphire, the transparent substrate 130 can be etched to form a conductive via through the transparent substrate 130. The conductive via is filled with conductive material to form a conductive contact 134, which is electrically connected to the first light-emitting structure 120.

[0090] S106, with the second reflective layer 140 facing the second surface 132, the second light-emitting structure 150 and the first light-emitting structure 120 are bonded together, with reference to... Figure 9 As shown.

[0091] In the embodiments of this application, the second light-emitting structure 150 and the first light-emitting structure 120 are bonded with the second reflective layer 140 facing the second surface 132 of the transparent substrate 130 to achieve a three-dimensional structure.

[0092] S107, the third light-emitting structure 170 and the second substrate 102 are stripped apart, reference Figure 10 As shown.

[0093] In this embodiment of the application, after bonding the transparent substrate 130 and the second light-emitting structure 150, the third light-emitting structure 170 and the second substrate 102 can be peeled off.

[0094] S108, forming a first electrode 181, a second electrode 182, a third electrode 183, and a fourth electrode 184, referenced. Figure 2 As shown.

[0095] In the embodiments of this application, after the third light-emitting structure 170 and the second substrate 102 are stripped, a first electrode 181, a second electrode 182, a third electrode 183 and a fourth electrode 184 are formed respectively. The second electrode 182 is located on the side surface of the first reflective layer 110 away from the first light-emitting structure 120. The first electrode 181 penetrates the first reflective layer 110 and at least part of the first light-emitting structure 120. The third electrode 183 penetrates the third light-emitting structure 170 to the third reflective layer 160. The fourth electrode 184 is located on the side surface of the third light-emitting structure 170 away from the third reflective layer 160.

[0096] In practical applications, since multiple second light-emitting structures 150 are formed on the first substrate 101 and multiple third light-emitting structures 170 are formed on the second substrate 102, before bonding the second light-emitting structures 150 and the third light-emitting structures 170, the cutting areas between the multiple second light-emitting structures 150 and the cutting areas before the multiple third light-emitting structures 170 can be etched to form multiple independent second light-emitting structures 150 and third light-emitting structures 170. Adhesive can be provided in the cutting areas to bond the multiple second light-emitting structures 150 and the multiple third light-emitting structures 170, thereby improving the reliability of the process.

[0097] Accordingly, the cutting area between multiple first light-emitting structures 120 can be etched to form multiple independent first light-emitting structures 120, and then an adhesive can be placed in the cutting area to bond the multiple first light-emitting structures 120 together, thereby improving the reliability of the process.

[0098] In practical applications, in order to improve the bonding alignment of the first light-emitting structure 120 and the second light-emitting structure 150, a film expansion process can be performed after the second light-emitting structure 150 and the third light-emitting structure 170 are bonded, so that the cutting area between the second light-emitting structures 150 is enlarged. Adhesive is placed in the enlarged cutting area so that the distance between the second light-emitting structures 150 after the enlarged cutting area is consistent with the center position of the second light-emitting structure 150 and the first light-emitting structure 120 overlapping when the second light-emitting structure 150 and the transparent substrate 130 are subsequently bonded.

[0099] After forming the micro light-emitting diode with the vertical structure provided in the embodiments of this application, the adhesive can be etched away to separate and form multiple independent micro light-emitting diodes.

[0100] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the method embodiments are basically similar to the structural embodiments, so they are described more simply; relevant parts can be referred to the descriptions of the structural embodiments.

[0101] The above description is merely a preferred embodiment of this application. Although this application has disclosed preferred embodiments above, it is not intended to limit this application. Any person skilled in the art can make many possible variations and modifications to the technical solutions of this application using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the technical solutions of this application. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this application without departing from the content of the technical solutions of this application shall still fall within the protection scope of the technical solutions of this application.

Claims

1. A miniature light-emitting diode, characterized in that, include: A first reflective layer, a first light-emitting structure, a transparent substrate, a second reflective layer, a second light-emitting structure, a third reflective layer, and a third light-emitting structure are sequentially stacked. The transparent substrate is a frustum or truncated pyramid structure. The transparent substrate has a first surface in contact with the first light-emitting structure, a second surface in contact with the second light-emitting structure, and an inclined sidewall. The area of ​​the first surface is larger than the area of ​​the second surface. The first light-emitting structure emits light using the inclined sidewall. The reflectivity of the third reflective layer to the second light-emitting structure is less than a first threshold, and the reflectivity of the third reflective layer to the third light-emitting structure is greater than a second threshold. The first threshold is less than the second threshold. The first electrode is located on the surface of the first reflective layer away from the first light-emitting structure. The second electrode penetrates the first reflective layer and at least a portion of the first light-emitting structure; The third electrode extends through the third light-emitting structure to the third reflective layer; The fourth electrode is located on the surface of the third light-emitting structure away from the third reflective layer.

2. The miniature light-emitting diode according to claim 1, characterized in that, The light emission efficiency of the first light-emitting structure is determined based on the thickness of the transparent substrate and the ratio of the first surface to the second surface.

3. The miniature light-emitting diode according to claim 2, characterized in that, The thickness of the transparent substrate ranges from 50 to 120 micrometers, and the ratio of the first surface to the second surface ranges from [1, 2].

4. The miniature light-emitting diode according to claim 1, characterized in that, The second light-emitting structure and the third light-emitting structure are electrically connected through the third reflective layer.

5. The miniature light-emitting diode according to claim 1, characterized in that, The transparent substrate is made of sapphire or gallium nitride.

6. The miniature light-emitting diode according to claim 5, characterized in that, If the transparent substrate is made of sapphire, the transparent substrate has conductive contacts that electrically connect the second reflective layer and the first light-emitting structure.

7. The miniature light-emitting diode according to any one of claims 1-6, characterized in that, The first light-emitting structure is a blue light-emitting structure, the second light-emitting structure is a red light-emitting structure, and the third light-emitting structure is a green light-emitting structure.

8. The miniature light-emitting diode according to claim 7, characterized in that, The blue light emitting structure includes a second type of blue light conductive layer, a blue light emitting layer and a first type of blue light conductive layer stacked in sequence; the red light emitting structure includes a first type of red light conductive layer, a red light emitting layer and a second type of red light conductive layer stacked in sequence; and the green light emitting structure includes a second type of green light conductive layer, a green light emitting layer and a first type of green light conductive layer stacked in sequence.

9. A method for manufacturing a miniature light-emitting diode, characterized in that, include: A first light-emitting structure is formed on a transparent substrate, a second light-emitting structure is formed on the first substrate, and a third light-emitting structure is formed on the second substrate; A third reflective layer is formed on the surface of the third light-emitting structure, and a first reflective layer is formed on the surface of the first light-emitting structure. The reflectivity of the third reflective layer to the second light-emitting structure is less than a first threshold, and the reflectivity of the third reflective layer to the third light-emitting structure is greater than a second threshold. The first threshold is less than the second threshold. The second light-emitting structure and the third light-emitting structure are bonded together with the third reflective layer facing the second light-emitting structure. The second light-emitting structure and the first substrate are stripped apart, and a second reflective layer is formed on the exposed surface of the second light-emitting structure. The transparent substrate is cut to form a frustum structure or a truncated cone structure. The transparent substrate has a first surface in contact with the first light-emitting structure, a second surface away from the first light-emitting structure, and inclined sidewalls. The area of ​​the first surface is larger than the area of ​​the second surface. The second light-emitting structure and the first light-emitting structure are bonded together with the second reflective layer facing the second surface; The third light-emitting structure and the second substrate are stripped apart; A first electrode, a second electrode, a third electrode, and a fourth electrode are formed. The first electrode is located on the side surface of the first reflective layer away from the first light-emitting structure. The second electrode penetrates the first reflective layer and at least part of the first light-emitting structure. The third electrode penetrates the third light-emitting structure to the third reflective layer. The fourth electrode is located on the side surface of the third light-emitting structure away from the third reflective layer.

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