Multicolor LED pixel units and micro LED display panels

Abstract

A method for manufacturing a micro light emitting diode (LED) display panel (650), comprising: forming a stack structure on a wafer substrate (500), the stack structure comprising, in bottom-to-top order, a first metal layer (101), a first type of light emitting layer (102), a second metal layer (201), and a second type of light emitting layer (202) (S4101); and forming a plurality of trenches (600) in the stack structure, the plurality of trenches (600) defining a plurality of micro LED display panel regions (550). (S4102), patterning the second type light emitting layer (202) and the second metal layer (201) (S4103), selectively etching the stack structure to expose sides of the first metal layer (101) to form a plurality of first LEDs (01) and a plurality of second LEDs (02) in each micro LED display panel area (550), and cutting the wafer substrate (500) to form a plurality of micro LED display panels (650).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims the benefit of priority to U.S. Patent Application No. 17 / 886,850, filed August 12, 2022, which is a continuation-in-part of U.S. Patent Application No. 17 / 840,516, filed June 14, 2022, which is a continuation-in-part of U.S. Patent Application No. 16 / 567,123, filed September 11, 2019, and granted as Patent No. 11,362,133, the entire contents of which are incorporated herein by reference. [Technical Field]

[0002] The present disclosure relates generally to the field of micro light emitting diode technology, and more particularly to multicolor LED pixel units and micro LED display panels. [Background technology]

[0003] Light-emitting diodes (LEDs), a type of semiconductor diode, can convert electrical energy into light energy. Conventional LEDs contain a PN junction with unidirectional conduction. Under a positive bias, holes flow from the P region to the N region, and electrons flow from the N region to the P region. The combination of electrons in the N region and holes in the P region generates spontaneous excitation light. Electrons and holes have different energy states in different semiconductor materials, and therefore the energy generated by the combination of electrons and holes is different. The higher the energy, the shorter the wavelength of the excitation light. Therefore, LEDs can emit light of different wavelengths, from ultraviolet to infrared, allowing multicolor LEDs to be produced.

[0004] Multicolor LEDs, which emit white or other colored light, have a wide range of applications, most of which are in the display field. Traditional LED display panels are formed by assembling single-color LEDs one by one onto a substrate. The method for assembling single-color LEDs involves bonding the LEDs to an interconnect layer using metal wires or LED connection electrodes through a metal bonding process or other process. The assembly process for other colored LEDs cannot be performed until the assembly process for the single-color LEDs is complete, resulting in complex processes, increased processing difficulty, and higher manufacturing costs. Furthermore, multicolor display panels manufactured by assembling or forming single LEDs one by one consume high power and suffer from reduced brightness and color. Summary of the Invention

[0005] According to an aspect of the present disclosure, a method for manufacturing a micro light emitting diode (LED) display panel includes forming a stack structure on a wafer substrate, the stack structure comprising, in bottom-to-top order, a first metal layer, a first type light emitting layer, a second metal layer, and a second type light emitting layer; forming a plurality of trenches in the stack structure, the plurality of trenches defining a plurality of micro LED display panel regions; and patterning the second type light emitting layer and the second metal layer until a portion of a top surface of the first type light emitting layer is exposed. forming a plurality of first LEDs and a plurality of second LEDs in each micro LED display panel area by patterning the second type light emitting layer and the second metal layer and then selectively etching the stack structure to expose side surfaces of the first metal layer, wherein each first LED includes the first metal layer and the first type light emitting layer, and each second LED includes the first metal layer, the first type light emitting layer, the second metal layer, and the second type light emitting layer; and cutting the wafer substrate to form a plurality of micro LED display panels. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a cross-sectional view illustrating a multi-color light-emitting pixel unit according to one embodiment of the present disclosure. [Figure 2] 1 is a cross-sectional view illustrating a multi-color light-emitting pixel unit according to one embodiment of the present disclosure. [Figure 3] 1 is a cross-sectional view illustrating a multi-color light-emitting pixel unit according to one embodiment of the present disclosure. [Figure 4] FIG. 2 is a top view illustrating a multi-color light-emitting pixel unit according to one embodiment of the present disclosure. [Figure 5] 1 is a cross-sectional view illustrating a multi-color light-emitting pixel unit according to one embodiment of the present disclosure. [Figure 6] 2 is a flowchart illustrating a method of fabricating the multi-color light-emitting pixel unit shown in FIG. 1 according to one embodiment of the present disclosure. [Figure 7] 7A-7C are cross-sectional views illustrating structures formed in the method steps of FIG. 6 according to one embodiment of the present disclosure. [Figure 8] 7A-7C are cross-sectional views illustrating structures formed in the method steps of FIG. 6 according to one embodiment of the present disclosure. [Figure 9] 7A-7C are cross-sectional views illustrating structures formed in the method steps of FIG. 6 according to one embodiment of the present disclosure. [Figure 10] 7A-7C are cross-sectional views illustrating structures formed in the method steps of FIG. 6 according to one embodiment of the present disclosure. [Figure 11] 7 is a flowchart illustrating details of step S601 of FIG. 6 according to one embodiment of the present disclosure. [Figure 12] 12A-12C are cross-sectional views illustrating the structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 13] 12A-12C are cross-sectional views illustrating the structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 14] 12A-12C are cross-sectional views illustrating the structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 15] 12A-12C are cross-sectional views illustrating the structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 16]12A-12C are cross-sectional views illustrating the structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 17] 12A-12C are cross-sectional views illustrating the structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 18] 12A-12C are cross-sectional views illustrating the structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 19] 12A-12C are cross-sectional views illustrating the structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 20] 12A-12C are cross-sectional views illustrating the structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 21] 12A-12C are cross-sectional views illustrating the structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 22] 7 is a flowchart illustrating details of step S604 of FIG. 6 according to one embodiment of the present disclosure. [Figure 23] 23 is a cross-sectional view illustrating a structure formed in the step of FIG. 22 according to one embodiment of the present disclosure. [Figure 24] 23 is a cross-sectional view illustrating a structure formed in the step of FIG. 22 according to one embodiment of the present disclosure. [Figure 25] 23 is a cross-sectional view illustrating a structure formed in the step of FIG. 22 according to one embodiment of the present disclosure. [Figure 26] 1A-1C are cross-sectional views illustrating structures formed during a process of manufacturing a first electrical connector according to one embodiment of the present disclosure. [Figure 27] 1A-1C are cross-sectional views illustrating structures formed during a process of manufacturing a first electrical connector according to one embodiment of the present disclosure. [Figure 28] FIG. 1 is a cross-sectional view illustrating a multi-color light-emitting pixel unit having a micro-gap structure according to one embodiment of the present disclosure. [Figure 29] 4 is a flowchart illustrating a method of manufacturing the multi-color light-emitting pixel unit shown in FIG. 3 according to one embodiment of the present disclosure. [Figure 30] 30A-30C are cross-sectional views illustrating structures formed in the method steps of FIG. 29 according to one embodiment of the present disclosure. [Figure 31] 30A-30C are cross-sectional views illustrating structures formed in the method steps of FIG. 29 according to one embodiment of the present disclosure. [Figure 32] 30A-30C are cross-sectional views illustrating structures formed in the method steps of FIG. 29 according to one embodiment of the present disclosure. [Figure 33] 30A-30C are cross-sectional views illustrating structures formed in the method steps of FIG. 29 according to one embodiment of the present disclosure. [Figure 34] 30A-30C are cross-sectional views illustrating structures formed in the method steps of FIG. 29 according to one embodiment of the present disclosure. [Figure 35] 30 is a flowchart illustrating details of step S701 of FIG. 29 according to one embodiment of the present disclosure. [Figure 36] 1A-1C are cross-sectional views of micro-gap structures formed in three types of light emitting layers according to one embodiment of the present disclosure. [Figure 37] 30 is a flowchart illustrating details of step S705 of FIG. 29 according to one embodiment of the present disclosure. [Figure 38] 38 is a cross-sectional view illustrating a structure formed in the step of FIG. 37 according to one embodiment of the present disclosure. [Figure 39] 38 is a cross-sectional view illustrating a structure formed in the step of FIG. 37 according to one embodiment of the present disclosure. [Figure 40] 38 is a cross-sectional view illustrating a structure formed in the step of FIG. 37 according to one embodiment of the present disclosure. [Figure 41] 1 is a flowchart illustrating a method for manufacturing a micro LED display panel according to one embodiment of the present disclosure. [Figure 42] 42A-42C are cross-sectional views illustrating structures formed by the method steps of FIG. 41. [Figure 43] 42A-42C are cross-sectional views illustrating structures formed by the method steps of FIG. 41. [Figure 44] 42A-42C are top views of structures formed by the method steps of FIG. 41. [Figure 45] 42A-42C are cross-sectional views illustrating structures formed by the method steps of FIG. 41. [Figure 46]42A-42C are cross-sectional views illustrating structures formed by the method steps of FIG. 41. [Figure 47] 42A-42C are cross-sectional views illustrating structures formed by the method steps of FIG. 41. [Figure 48] 42A-42C are top views of structures formed by the method steps of FIG. 41. DETAILED DESCRIPTION OF THE INVENTION

[0007] In order to provide a further understanding of the present invention, reference will now be made in detail to the preferred embodiments. The specific embodiments described and the accompanying drawings are merely illustrative of specific ways to make and use the invention and do not limit the scope of the invention or the appended claims.

[0008] Hereinafter, the present disclosure will be further described by the embodiments of the present disclosure in combination with Figures 1 to 44. It should be noted that all the accompanying drawings are in a very simplified form, and the inaccurate scale is only used to help explain the embodiments of the present disclosure in a simple and clear manner.

[0009] The multicolor light-emitting pixel unit disclosed herein includes at least one type of light-emitting transistor or several types of light-emitting transistors. Each type of light-emitting transistor includes a top conductive layer, a bottom conductive layer, and a light-emitting layer between the top and bottom conductive layers. All light-emitting transistors share the same top and bottom conductive layers. Note that the light-emitting layer may be a single layer or multiple layers. An intermediate layer may be disposed between two of the multiple light-emitting layers in the same light-emitting diode. The multicolor light-emitting pixel unit includes first to Mth types of light-emitting transistors, where M is an integer greater than or equal to 2. Each of the first to Mth types of light-emitting transistors includes at least the same type of light-emitting layer. For example, each of the first to Mth types of light-emitting transistors includes a first type of light-emitting layer. Each of the second to Mth types of light-emitting layers is different from the first type of light-emitting layer. The present disclosure also provides a microdisplay panel having a plurality of the above-described pixel units arranged in a matrix.

[0010] In some embodiments, the light-emitting transistor can be at least one of a light-emitting diode (LED), a Schottky light-emitting transistor, etc. The top conductive layer of the light-emitting transistor can be, but is not limited to, a transparent conductive layer, and the bottom conductive layer of the light-emitting transistor can be, but is not limited to, a metal layer. Hereinafter, an LED will be used as an example of a light-emitting transistor, but this does not limit the scope of the present disclosure. Those skilled in the art can change the LED into other light-emitting transistors through conventional technical means.

[0011] FIG. 1 is a cross-sectional view illustrating a multicolor light-emitting pixel unit 1000 according to one embodiment of the present disclosure. Referring to FIG. 1, the multicolor light-emitting pixel unit 1000 includes at least a first type LED 01 and a second type LED 02 arranged side by side on a substrate 100. The tops of the first type LED 01 and the second type LED 02 are not on the same horizontal plane. The type of the first type LED 01 is different from the type of the second type LED 02. Here, as shown in FIG. 1, the top of the first type LED 01 is lower than the top of the second type LED 02. According to one embodiment, the first type LED 01 is selected from one of a red LED, a green LED, a blue LED, a yellow LED, an orange LED, or a cyan LED, and the second type LED 02 is selected from one of a green LED, a blue LED, a red LED, a yellow LED, an orange LED, or a cyan LED. Furthermore, the size of the light-emitting area of the first type LED 01 is different from the size of the light-emitting area of the second type LED 02. For example, the first type LED 01 is a red LED and the second type LED 02 is a green LED, and the size of the light-emitting area of the red LED is different from the size of the light-emitting area of the green LED. Furthermore, depending on the different colors that may be required, the light-emitting area of the green LED can be smaller than the light-emitting area of the red LED.

[0012] Furthermore, an isolation structure 07 is disposed between the first-type LED 01 and the second-type LED 02. In the embodiment shown in FIG. 1, the isolation structure 07 between the first-type LED 01 and the second-type LED 02 is an isolation trench. The multicolor light-emitting pixel unit 1000 includes a first metal layer, a first-type light-emitting layer, a second metal layer, and a second-type light-emitting layer. As shown in FIG. 1, the first-type LED 01 includes, from bottom to top, at least a first segment 101-1 of the first metal layer and a first segment 102-1 of the first-type light-emitting layer. The first segment 101-1 of the first metal layer constitutes the bottom conductive layer of the first-type LED 01. The second-type LED 02 includes, from bottom to top, at least a second segment 101-2 of the first metal layer, a second segment 102-2 of the first-type light emitting layer, a first segment 201-1 of the second metal layer, a first segment 202-2 of the second-type light emitting layer, and a first electrical connector 203. The first segment 101-1 of the first metal layer and the second segment 101-2 of the first metal layer are electrically connected to the substrate 100. An isolation structure 07 separates the first segment 101-1 of the first metal layer in the first-type LED 01 from the second segment 101-2 of the first metal layer in the second-type LED 02. The isolation structure 07 also separates the first segment 102-1 of the first-type light emitting layer in the first-type LED 01 from the second segment 102-2 of the first-type light emitting layer in the second-type LED 02. Furthermore, to simplify the manufacturing process, the first segment 201-1 of the second metal layer, the second segment 102-2 of the first light emitting layer, and the second segment 101-2 of the first metal layer in the second-type LED 02 are electrically connected to each other by a first electrical connector 203. According to one embodiment, the first electrical connector 203 can be attached to and contact some or all of the sidewall surfaces of the second-type LED 02. Alternatively, the first electrical connector 203 can be attached to and contact only the surfaces of the first segment 201-1 of the second metal layer and the second segment 101-2 of the first metal layer in the second-type LED 02.Further alternatively, the first electrical connector 203 can be formed as a conductive side arm attached to and contacting the sidewalls of the first segment 201-1 of the second metal layer, the second segment 102-2 of the first-type light emitting layer, and the second segment 101-2 of the first metal layer. The electrical connector 203 between the second segment 101-2 of the first metal layer and the first segment 201-1 of the second metal layer in the second-type LED 02 can have another shape, such as a curve. In the embodiment shown in FIG. 1 , the first electrical connector 203 is attached to the sidewall of the second-type LED 02 so that the first electrical connector 203 conforms to the surface topography of the sidewall of the second-type LED 02.

[0013] Referring to FIG. 1 , an upper isolation layer 04 and an upper transparent conductive layer 05 are disposed on a first segment 102-1 of a first type of light emitting layer in a first type LED 01 and a first segment 202-1 of a second type of light emitting layer in a second type LED 02. The upper isolation layer 04 covers the first segment 102-1 of the first type of light emitting layer, the first segment 202-1 of the second type of light emitting layer, and the exposed substrate 100. The upper isolation layer 04 has openings that expose portions of the upper surfaces of the first segment 102-1 of the first type of light emitting layer and the first segment 202-1 of the second type of light emitting layer. The upper transparent conductive layer 05 covers the upper isolation layer 04 and is formed within the openings in the upper isolation layer 04, thereby contacting the exposed upper surfaces of the first segment 102-1 of the first type of light emitting layer and the first segment 202-1 of the second type of light emitting layer through the openings.

[0014] The substrate 100 is an integrated circuit (IC) substrate. The IC substrate includes an interconnect layer electrically connected to the first segment 101-1 of the first metal layer in the first type LED 01 and the second segment 101-2 of the first metal layer in the second type LED 02. The first electrical connector 203 is connected to the second segment 101-2 of the first metal layer in the second type LED 02, and thus the first electrical connector 203 is connected to the interconnect layer in the substrate 100. Further, referring to FIG. 1 , the bottom of the first electrical connector 203 extends to the substrate 100 to connect to the interconnect layer. Here, the IC substrate includes at least a drive circuit. The drive circuit individually controls each LED.

[0015] 2 is a cross-sectional view illustrating a multi-color light-emitting pixel unit 2000 according to one embodiment of the present disclosure. Referring to FIG. 2, the multi-color light-emitting pixel unit 2000 includes at least a first type LED 01, a second type LED 02, and a third type LED 03 arranged on the same substrate 100. The third type LED 03 is different from the first type LED 01 and the second type LED 02. Here, the first type LED 01 is selected from one of a red LED, a green LED, a blue LED, a yellow LED, an orange LED, or a cyan LED; the second type LED 02 is selected from one of a green LED, a blue LED, a red LED, a yellow LED, an orange LED, or a cyan LED; and the third type LED 03 is selected from one of a blue LED, a red LED, a green LED, a yellow LED, an orange LED, or a cyan LED. For example, a red LED is selected as the first type LED01, a green LED is selected as the second type LED02, and a blue LED is selected as the third type LED03. Referring to FIG. 2, the height of the third type LED03 is different from the height of the first type LED01. Furthermore, the height of the first type LED01 is different from the height of the second type LED02, and the height of the second type LED02 is the same as the height of the third type LED03. In other embodiments, as shown in FIG. 3, the height of the third type LED03, the height of the first type LED01, and the height of the second type LED02 may be different from each other.

[0016] In the multi-color light-emitting pixel unit 2000, the structures of the first type LED01 and the second type LED02 are the same as those of the first type LED01 and the second type LED02 in the multi-color light-emitting pixel unit 2000, so detailed descriptions will not be repeated. The third type LED03 in the multi-color light-emitting pixel unit 2000 includes, from bottom to top, at least a third segment 101-3 of the first metal layer, a third segment 102-3 of the first type light-emitting layer, a first segment 301-1 of the third metal layer, and a first segment 302-1 of the third type light-emitting layer, as well as a second electrical connector 303 connecting the third segment 101-3 of the first metal layer and the first segment 301-1 of the third metal layer. The multi-color light-emitting pixel unit 2000 also includes an upper isolation layer 04 that covers the first type LED 01, the second type LED 02, and the third type LED 03 and has openings that expose portions of the first segment 102-1 of the first type light-emitting layer, the first segment 202-1 of the second type light-emitting layer, and the first segment 302-1 of the third type light-emitting layer in the first type LED 01. An upper electrode layer 05 is formed on the upper isolation layer 04 and is in contact with the first segment 102-1 of the first type light-emitting layer, the first segment 202-1 of the second type light-emitting layer, and the first segment 302-1 of the third type light-emitting layer through the openings in the upper isolation layer 04.

[0017] 3 is a cross-sectional view illustrating a multi-color light-emitting pixel unit 3000 according to one embodiment of the present disclosure. Referring to FIG. 3, in the multi-color light-emitting pixel unit 3000, the top of the third-type LED03 is higher than the top of the second-type LED02, and the height of the first-type LED is different from the height of the second-type LED03.

[0018] FIG. 4 is a top view of a multicolor light-emitting pixel unit 4000 according to one embodiment of the present disclosure. The multicolor light-emitting pixel unit 4000 can be the multicolor light-emitting pixel unit 2000 shown in FIG. 2 or the multicolor light-emitting pixel unit 3000 shown in FIG. 3. While FIG. 4 illustrates an arrangement of three types of LEDs 01, 02, and 03 in the pixel unit, the present disclosure also encompasses other arrangements, such as a matrix. Here, the size of the light-emitting area of the third type LED 03 is different from the size of the light-emitting area of the first type LED 01 and different from the size of the light-emitting area of the second type LED 02. For example, the first type LED 01 is a red LED, the second type LED 02 is a green LED, and the third type LED 03 is a blue LED. The size of each light-emitting area of the first, second, and third types LEDs 01, 02, and 03 can be determined according to the required color of light to be emitted by the multicolor light-emitting pixel unit 4000. When white light is required, the size of the light-emitting area of the red LED is larger than that of the green LED, and the size of the light-emitting area of the blue LED is larger than that of the green LED. To achieve a better light-emitting effect, the distance between the red LED and the blue LED is larger than that between the blue LED and the green LED, and the distance between the red LED and the green LED is larger than that between the blue LED and the green LED, as shown in Figure 4.

[0019] Referring again to FIG. 3 , an isolation structure 07 is disposed between two of the first-type LED 01, the second-type LED 02, and the third-type LED 03. The isolation structure is an isolation trench. The first-type LED 01, the second-type LED 02, and the third-type LED 03 are formed from a first metal layer 101, a first-type light-emitting layer 102, a second metal layer 201, a second-type light-emitting layer 202, a third metal layer 301, and a third-type light-emitting layer 302. The first-type LED 01 and the second-type LED 02 in FIG. 3 are the same as the first-type LED 01 and the second-type LED 02 in FIG. 2. Specifically, as shown in FIG. 3 , the first-type LED 01 includes, from bottom to top, at least a first segment 101-1 of the first metal layer and a first segment 102-1 of the first-type light-emitting layer. The second type LED02 includes, from bottom to top, at least a second segment 101-2 of the first metal layer, a second segment 102-2 of the first type light emitting layer, a first segment 201-1 of the second metal layer, and a first segment 202-1 of the second type light emitting layer, and a first electrical connector 203. The third type LED03 includes, from bottom to top, at least a third segment 101-3 of the first metal layer, a third segment 102-3 of the first type light emitting layer, a second segment 201-2 of the second metal layer, a second segment 202-2 of the second type light emitting layer, a first segment 301-1 of the third metal layer, and a first segment 302-1 of the third type light emitting layer, and a second electrical connector 303. 3, the first segment 101-1 of the first metal layer, the second segment 101-2 of the first metal layer, and the third segment 101-3 of the first metal layer are electrically connected to the substrate 100. The first electrical connector 203 in the second type LED 02 electrically connects the first segment 201-1 of the second metal layer to the second segment 101-2 of the first metal layer. The second electrical connector 303 in the third type LED 03 electrically connects the first segment 301-1 of the third metal layer to the second segment 201-2 of the second metal layer and the third segment 101-3 of the first metal layer.The isolation structure 07 separates the first segment 101-1 of the first metal layer in the first type LED 01 from the second segment 101-2 of the first metal layer in the second type LED 02 and the third segment 101-3 of the first metal layer in the third type LED 03, and separates the first segment 102-1 of the first type light emitting layer in the first type LED 01 from the second segment 102-2 of the first type light emitting layer in the second type LED 02 and the third segment 102-3 of the first metal layer in the third type LED 03. The first segment 201-1 of the second metal layer in the second type LED02 is separated from the third segment 102-3 of the first type light emitting layer in the third type LED03, the first segment 201-1 of the second metal layer in the second type LED02 is separated from the second segment 201-2 of the second metal layer in the third type LED03, and the first segment 202-1 of the second type light emitting layer in the second type LED02 is separated from the second segment 202-2 of the second type light emitting layer in the third type LED03. It should be noted that the first electrical connector 203 is used to connect the second segment 102-2 of the first type light emitting layer with the second segment 101-2 of the first metal layer in the second type LED 02, and the second electrical connector 303 is used to connect the second segment 202-2 of the second type light emitting layer and the third segment 102-3 of the first type light emitting layer with the third segment 101-3 of the first metal layer in the third type LED 03. Therefore, to simplify the manufacturing process, the first electrical connector 203 further connects the second segment 102-2 of the first type light emitting layer with the second segment 101-2 of the first metal layer, similar to FIG. That is, in the second type LED 02, the first electrical connector 203 connects the first segment 201-1 of the second metal layer and the second segment 102-2 of the first type light emitting layer with the second segment 101-2 of the first metal layer, and the second electrical connector 303 further connects the second segment 202-2 of the second type light emitting layer with the third segment 101-3 of the first metal layer.That is, in the third type LED 03, the second electrical connector 303 connects the first segment 301-1 of the third metal layer, the second segment 202-2 of the second type light emitting layer, and the second segment 201-2 of the second metal layer with the third segment 101-3 of the first metal layer. Alternatively, the second electrical connector 303 further connects the second segment 202-2 of the second type light emitting layer and the third segment 102-3 of the first type light emitting layer with the third segment 101-3 of the first metal layer. That is, in the third-type LED03, the second electrical connector 303 connects the first segment 301-1 of the third metal layer, the second segment 202-2 of the second-type light emitting layer, the second segment 201-2 of the second metal layer, and the third segment 102-3 of the first-type light emitting layer with the third segment 101-3 of the first metal layer. Furthermore, the bottoms of the first electrical connector 203 and the second electrical connector 303 directly contact the substrate 100 separately, simplifying the manufacturing process. Note that the first electrical connector 203 and the second electrical connector 303 are made of a conductive metal. In one embodiment, the second electrical connector 303 is attached to and contacts the sidewall surface of the third-type LED03.

[0020] In one embodiment, the first type light emitting layer is a red light emitting layer, the second type light emitting layer is a green light emitting layer, and the third type light emitting layer is a blue light emitting layer, and the first type LED01 is a red LED01, the second type LED02 is a green LED02, and the third type LED03 is a blue LED03. In the red LED01, a voltage applied between the top transparent conductive layer 05 and the first segment 101-1 of the first metal layer is applied to the first segment 102-1 of the red light emitting layer, causing the first segment 102-1 of the red light emitting layer in the red LED01 to emit red light. In the green LED 02, the first electrical connector 203 electrically connects the second segment 102-2 of the red light emitting layer to the second segment 101-2 of the first metal layer so that a voltage applied between the upper transparent conductive layer 05 and the second segment 101-2 of the first metal layer is applied only to the first segment 202-1 of the green light emitting layer, so that only the first segment 202-1 of the green light emitting layer in the green LED 02 emits green light, and the second segment 102-2 of the red light emitting layer in the green LED 02 does not emit light. In the third type LED 03, the second electrical connector 303 electrically connects the third segment of the red light emitting layer 102-3 and the second segment of the green light emitting layer 202-2 to the third segment of the first metal layer 101-3 so that a voltage applied between the upper transparent conductive layer 05 and the third segment of the first metal layer 101-3 is applied only to the first segment of the blue light emitting layer 302-1, so that only the first segment of the blue light emitting layer 302-1 in the blue LED 03 emits blue light, and the third segment of the red light emitting layer 102-3 and the second segment of the green light emitting layer 202-2 in the blue LED 03 do not emit light.

[0021] 3 , the upper isolation layer 04 and the upper transparent conductive layer 05 are disposed on the first type LED 01, the second type LED 02, and the third type LED 03. The upper isolation layer 04 covers the first segment 102-1 of the first type light emitting layer, the first segment 202-1 of the second type light emitting layer, the first segment 302-1 of the third type light emitting layer, and the exposed substrate 100. Openings are disposed in the upper isolation layer 04 to expose portions of the top surfaces of the first segment 102-1 of the first type light emitting layer, the first segment 202-1 of the second type light emitting layer, and the first segment 302-1 of the third type light emitting layer. The upper transparent conductive layer 05 covers the upper isolation layer 04 and is formed within the openings of the upper isolation layer 04, thereby contacting the exposed upper surfaces of the first segments 102-1 of the first type light emitting layer, the first segments 202-1 of the second type light emitting layer, and the first segments 302-1 of the third type light emitting layer.

[0022] A detailed description of the substrate 100 in the multi-color light-emitting pixel unit 3000 having at least three types of LEDs corresponds to the description of FIG. 1 and will not be repeated here. Note that the interconnect layer in the IC substrate 100 electrically connects the first type LEDs 01, the second type LEDs 02, and the third type LEDs 03. The driver circuit in the IC substrate 100 individually controls each LED.

[0023] 1-4, one or more of the light emitting layers 102, 202, and 302 may have a microgap structure. For example, in the multicolor light emitting pixel unit 1000 shown in FIG. 1, the first type light emitting layer 102 may have a microgap structure, or the second type light emitting layer 202 may have a microgap structure, or both the first type light emitting layer 102 and the second type light emitting layer 202 may have a microgap structure. As another example, in the multicolor light-emitting pixel unit 3000 shown in Figure 3, the first type light-emitting layer 102 can have a microgap structure, or the second type light-emitting layer 202 can have a microgap structure, or the third type light-emitting layer 302 can have a microgap structure, or both the first type light-emitting layer 102 and the second type light-emitting layer 202 can have a microgap structure, or both the second type light-emitting layer 202 and the third type light-emitting layer 302 can have a microgap structure, or both the first type light-emitting layer 102 and the third type light-emitting layer 302 can have a microgap structure, or all of the first type light-emitting layer 102, the second type light-emitting layer 202, and the third type light-emitting layer 302 can have a microgap structure. Here, each of the microgap structures in the multicolor light-emitting pixel units 1000 to 3000 shown in Figures 1 to 3 can be, but is not limited to, an air gap. The air gap is sealed. In order to release stress in the light emitting layer and avoid bending of the light emitting layer without affecting the light emitting efficiency of the light emitting layer, the cross-sectional dimension of the air gap is preferably 2 nm or less, where the cross-sectional dimension of the air gap can be the diameter of the cross-section of the air gap, or the length or width of the cross-section of the air gap.

[0024] 5 is a cross-sectional view illustrating a multicolor light-emitting pixel unit 5000 according to one embodiment of the present disclosure. As shown in FIG. 5, each of the first type light-emitting layer 102, the second type light-emitting layer 202, and the third type light-emitting layer 302 can have multiple microgap structures 06. Each of the microgap structures 06 extends along a direction perpendicular to the substrate 100 and penetrates a corresponding light-emitting layer, such as the first type light-emitting layer 102, the second type light-emitting layer 202, or the third type light-emitting layer 302. When multiple light-emitting layers are used in one embodiment, the microgap structure 06 is disposed in at least one light-emitting layer, preferably the upper light-emitting layer.

[0025] 5 , the microgap structures 06 are staggered relative to one another within the multiple light emitting layers. That is, the microgap structures 06 within the first-type light emitting layer 102 are not vertically aligned with the microgap structures 06 within the second-type light emitting layer 202, and the microgap structures 06 within the second-type light emitting layer 202 are not vertically aligned with the microgap structures 06 within the third-type light emitting layer 302. In each of the second-type LED 02 and the third-type LED 03, the microgap structures within the first-type light emitting layer 102 are separated and sealed between a second metal layer 201 above the first-type light emitting layer 102 and a first metal layer 101 below it. In the third type LED 03, the microgap structure 06 in the second type light emitting layer 202 is separated and sealed between a third metal layer 301 on top of the second type light emitting layer 202 and the second metal layer 201 at its bottom, and the microgap structure 06 in the third type light emitting layer 302 is separated and sealed between an upper separation layer 04 on top of the third type light emitting layer 302 and the third metal layer 301 at its bottom.

[0026] Similarly, in another embodiment of the present disclosure, in a multicolor light-emitting pixel unit including first to Mth types of LEDs, the Mth type of LED has M light-emitting layers, and a metal layer is disposed at the bottom of each light-emitting layer, where M is a positive integer greater than or equal to 2. In each of the first to Mth types of LEDs, an upper conductive layer (as the upper conductive layer) is disposed on the upper light-emitting layer, so that the microgap structures in the upper light-emitting layer can be separated and sealed between the upper conductive layer and the metal layer at the bottom of the upper light-emitting layer. The microgap structures in all light-emitting layers are separated and sealed between metal layers at the top and bottom of the respective light-emitting layers, respectively.

[0027] Furthermore, similar to the multicolor light-emitting pixel units 1000 to 4000 of FIGS. 1 to 4 , a multicolor light-emitting pixel unit according to another embodiment of the present disclosure includes a plurality of LEDs, including a first type LED to an Mth type LED. The Mth type LED includes all of the light-emitting layers and metal layers of the (M-1)th type LED, and at least the Mth light-emitting layer and the Mth metal layer. Based on this, the Mth type LED has an (M-1)th electrical connector connected to the Mth metal layer, the (M-1)th metal layer, ..., and the first metal layer. Furthermore, the (M-1)th electrical connector can be connected to the Mth metal layer, the (M-1)th type light-emitting layer, the (M-1)th metal layer, ..., the first type light-emitting layer, and the first metal layer. The arrangement of the (M-1)th electrical connector can refer to the description of the first electrical connector 203 in FIG. 1. The first to (M-1)th electrical connectors connect the first to Mth metal layers, and the first to (M-1)th electrical connectors can be in direct contact with the substrate and the first metal layer. Here, the first type LEDs are different from the Mth type LEDs. Furthermore, all types of LEDs can be selected from one of red LEDs, green LEDs, blue LEDs, yellow LEDs, orange LEDs, purple LEDs, and cyan LEDs. In this specification, the different color LEDs are conventional LEDs, which are known to those skilled in the art and will not be described herein. Furthermore, the first type LEDs to the Mth type LEDs are spaced apart on the same substrate. An upper isolation layer covers the exposed surface of the substrate and the exposed surfaces of the first to Mth type LEDs. The upper isolation layer of all types of LEDs has an opening, and a transparent conductive layer covers the surface of the upper isolation layer and fills the opening, and the transparent conductive layer at the bottom of the opening electrically contacts the upper light-emitting layer of all types of LEDs. 4 and 5, in a pixel unit having M types of LEDs, the sizes of the light emission areas of the first to Mth types of LEDs are different from each other. According to the arrangement of the LEDs in the pixel unit, the size of the light emission area of the first type of LED is larger than the size of the light emission area of the other types of LEDs.Optionally, the first type of LED is a red LED having a light emitting area larger than the light emitting area of the other types of LEDs. Alternatively, the other types of LEDs include at least a green LED or a blue LED.

[0028] According to one embodiment of the present disclosure, there is also provided a multicolor microdisplay panel, which includes a plurality of multicolor pixel units arranged in a matrix, where the multicolor pixel units can be the LED pixel units described above.

[0029] The method for fabricating a multi-color light-emitting pixel unit will be further described below with reference to the drawings.

[0030] Figure 6 is a flowchart illustrating a method for fabricating the multi-color light-emitting pixel unit shown in Figure 1 according to one embodiment of the present disclosure. Figures 7 to 10 are cross-sectional views illustrating a structure formed in the steps shown in Figure 6 according to one embodiment of the present disclosure. Referring to Figure 6, the method for fabricating the multi-color light-emitting pixel unit shown in Figure 1 includes the following steps.

[0031] 7 , in step S601, a stack structure including a first metal layer 101, a first-type light emitting layer 102, a second metal layer 201, and a second-type light emitting layer 202 is formed on a substrate 100 from bottom to top. In other words, the first-type light emitting layer 102 and the second-type light emitting layer 202 are stacked on the substrate 100 from bottom to top. The first metal layer 101 is formed on the bottom of the first-type light emitting layer 102. The second metal layer 201 is formed on the bottom of the second-type light emitting layer 202. The second metal layer 201 is disposed between the first-type light emitting layer 102 and the second-type light emitting layer 202.

[0032] More specifically, the substrate 100 can be, but is not limited to, an IC substrate.

[0033] Fig. 11 is a flowchart showing details of step S601 of Fig. 6 according to one embodiment of the present disclosure. Figs. 12 to 21 are cross-sectional views showing a structure formed in the steps shown in Fig. 11 according to one embodiment of the present disclosure. Referring to Fig. 11, step S601 further includes the following specific steps:

[0034] In step S101, referring to FIG. 12, a first metal bonding layer M01 is formed on the substrate 100, a first type light emitting layer 102 is formed on the first base B1, and a second metal bonding layer M02 is formed on the first type light emitting layer 102.

[0035] More specifically, the first metal bonding layer MOI can be prepared by physical vapor deposition, such as, but not limited to, evaporation or sputtering. The material of the first base B1 is designed according to the first type of light emitting layer 102. For example, the first base B1 can be based on gallium nitride (GaN). The first type of light emitting layer 102 can be formed on the first base B1 by, but not limited to, epitaxial growth. The second metal bonding layer MO2 can be prepared by physical vapor deposition, such as, but not limited to, evaporation.

[0036] In step S102, referring to FIG. 13 in combination with FIG. 12, the first base B1 is turned upside down so that the second metal bonding layer M02 faces the first metal bonding layer M01, and then the second metal bonding layer M02 is bonded to the first metal bonding layer M01 to form the first metal layer 101.

[0037] In step S103, referring to FIG. 14 in combination with FIG. 13, the first base B1 is removed.

[0038] Now, referring to FIG. 15, after the first base B1 is removed, step S103 may further include thinning the first-type light emitting layer 102.

[0039] Furthermore, according to one embodiment, after the first base B1 is removed or the first-type light emitting layer 102 is thinned and before the third metal bonding layer is formed, referring to FIG. 16 , step S103 may further include forming a microgap structure 06 in the first-type light emitting layer 102. The microgap structure 06 is formed by, but not limited to, photolithography and etching. In photolithography, a lithography pattern is designed according to the dimensions of the microgap structure 06. According to one embodiment, the cross-sectional dimension of the microgap structure pattern is 2 nm or less. Here, the cross-sectional dimension of the air gap may be the diameter of the cross section of the air gap, or the length or width of the cross section of the air gap.

[0040] In step S104, referring to FIG. 17, a third metal bonding layer M03 is formed on the first type light emitting layer 102, a second type light emitting layer 202 is formed on the second base B2, and a fourth metal bonding layer M04 is formed on the second type light emitting layer 202.

[0041] In step S105, referring to Figure 18 in combination with Figure 17, the second base B2 is turned upside down so that the fourth metal bonding layer M04 faces the third metal bonding layer M03, and the fourth metal bonding layer M04 is bonded to the third metal bonding layer M03 to form the second metal layer 201.

[0042] In step S106, referring to FIG. 19 in combination with FIG. 18, the second base B2 is removed.

[0043] Now, after removing the second base B2, referring to FIG. 20, in step S106, the second-type light emitting layer 202 is thinned.

[0044] According to one embodiment, after the second base B2 is removed or the second-type light emitting layer 202 is thinned, referring to Figure 21, in step S106, a microgap structure 06 is formed in the second-type light emitting layer 202. The microgap structure 06 is formed using a process similar to the process of forming the microgap structure 06 in the first-type light emitting layer 102. Therefore, the description of the process of forming the microgap structure 06 in the second-type light emitting layer 202 will not be repeated.

[0045] Referring again to FIGS. 6-10, the process after step S601 according to an embodiment of the present disclosure is further described below.

[0046] In step S602, referring to FIG. 8 , the second-type light-emitting layer 202 and the second metal layer 201 are patterned until a portion of the top of the first-type light-emitting layer 102 is exposed, thereby forming a step structure made by the second-type light-emitting layer 202 on the first-type light-emitting layer 102.

[0047] More specifically, the process of patterning the second-type light emitting layer 202 and the second metal layer 201 is carried out by photolithography and plasma etching. The process of patterning the second-type light emitting layer 202 and the second metal layer 201 also includes over-etching the top of the first-type light emitting layer 102. The parameters of the patterning process can be set according to actual needs, and are not limited herein.

[0048] In step S603, referring to FIG. 9 , the second type light emitting layer 202, the second metal layer 201, the first type light emitting layer 102, and the first metal layer 101 are etched according to the preset first type light emitting region A01 and the preset second type light emitting region A02, so as to segment the first type light emitting layer 102 in the first type light emitting region A01 from the first type light emitting layer 102 in the second type light emitting region A02, and to segment the first metal layer 101 in the first type light emitting region A01 from the first metal layer 101 in the second type light emitting region A02. As a result of step S603, a first type LED01 is formed, which includes a first segment 101-1 of the first metal layer and a first segment 102-1 of the first type light emitting layer, and a second type LED02 is formed, which includes a second segment 101-2 of the first metal layer, a second segment 102-2 of the first type light emitting layer, a first segment 201-1 of the second metal layer, and a second segment 202-1 of the second type light emitting layer.

[0049] Here, the etching process of the second-type light emitting layer 202, the second metal layer 201, the first-type light emitting layer 102, and the first metal layer 101 is carried out by photolithography and etching. The parameters of the etching process can be set according to actual needs.

[0050] According to one embodiment, as a result of step S603, the plurality of multicolor light-emitting pixel units are segmented from each other according to a preset pixel unit array. In this way, the pixel units and / or the light-emitting transistors in the array of pixel units can be prepared by one segmentation step, which simplifies the process, reduces manufacturing costs, and facilitates large-scale manufacturing in particular.

[0051] In step S604, referring to FIG. 10, in the second type light emitting region A02, a shared upper electrode layer 05 functioning as an extraction electrode for the second metal layer 201 is formed on the top of the first segment 102-1 of the first type light emitting layer and the first segment 202-1 of the second type light emitting layer.

[0052] Fig. 22 is a flowchart showing details of step S604 of Fig. 6 according to one embodiment of the present disclosure. Figs. 23 to 25 are cross-sectional views showing a structure formed in the step shown in Fig. 22 according to one embodiment of the present disclosure. Referring to Fig. 22, the specific process of step S604 includes the following steps.

[0053] In step S401, referring to FIG. 23, a portion of the first segment 202-1 of the second-type light emitting layer is removed so as to expose a portion of the first segment 201-1 of the second metal layer.

[0054] In step S402, referring to FIG. 24, in the second type light emitting region A02, a first electrical connector 203 is formed on the sidewalls and top of the first segment 201-1 of the second metal layer, the sidewalls of the second segment 102-2 of the first type light emitting layer, and the sidewalls of the second segment 101-2 of the first metal layer.

[0055] 26-27 are cross-sectional views showing a structure formed in steps of manufacturing the first electrical connector 203 according to an embodiment of the present disclosure. In step S402, the first electrical connector 203 is formed by the following specific steps:

[0056] In step S4021, referring to FIG. 26 in combination with FIG. 24, a mask Y is formed to shield areas without the first electrical connector 203, thereby exposing the top and sidewalls of the first segment 201-1 of the second metal layer, the sidewalls of the second segment 102-2 of the first type light emitting layer, and the sidewalls of the second segment 101-2 of the first metal layer in the second type light emitting area A02.

[0057] In step S4022, with reference to FIG. 27, after step S4021 is completed, a conductive material 203' is deposited on the substrate 100.

[0058] In step S4023, referring again to FIG. 10, in the second type light emitting region A02, the mask Y and the conductive material 203' on the mask Y are removed so that a first electrical connector 203 is formed on the top and sidewalls of the first segment 201-1 of the second metal layer, the sidewalls of the second segment 102-2 of the first type light emitting layer, and the sidewalls of the second segment 101-2 of the first metal layer.

[0059] The process for fabricating the shared top electrode layer 05 is further described below.

[0060] 25, in step S403, an isolation layer 04 is formed to cover the first type light emitting region A01, the second type light emitting region A02, and the surface of exposed substrate 100. The isolation layer 04 has openings over first segments 102-1 of the first type light emitting layer in the first type light emitting region A01 and first segments 202-1 of the second type light emitting layer in the second type light emitting region A02.

[0061] 10, in step S404, after step S403, a continuous shared top electrode layer 05 is formed, for example by deposition, over the entire substrate 100. The shared top electrode layer 05 formed in the openings connects the first segment 102-1 of the first-type light emitting layer in the first-type light emitting region A01 and the first segment 202-1 of the second-type light emitting layer in the second-type light emitting region A02.

[0062] FIG. 28 shows the structure of a multicolor light-emitting pixel unit having micro-gap structures in the first-type light-emitting layer 102 and the second-type light-emitting layer 202 according to one embodiment of the present disclosure.

[0063] Figure 29 is a flowchart illustrating a method of fabricating the multi-color light-emitting pixel unit 3000 shown in Figure 3 according to one embodiment of the present disclosure. Figures 30-34 are cross-sectional views illustrating a structure formed in the steps shown in Figure 6 according to one embodiment of the present disclosure. Referring to Figure 29, the method of fabricating the multi-color light-emitting pixel unit 3000 shown in Figure 3 includes the following steps.

[0064] 30 , in step S701, a stack structure is formed on a substrate 100, including, from bottom to top, a first metal layer 101, a first-type light emitting layer 102, a second metal layer 201, a second-type light emitting layer 202, a third metal layer 301, and a third-type light emitting layer 302. In other words, the first-type light emitting layer 102, the second-type light emitting layer 202, and the third-type light emitting layer 302 are stacked on the substrate 100 from bottom to top. The first metal layer 101 is formed on the bottom of the first-type light emitting layer 102. The second metal layer 201 is formed on the bottom of the second-type light emitting layer 202. The third metal layer 301 is formed on the bottom of the third-type light emitting layer 302. The second metal layer 201 is disposed between the first-type light emitting layer 102 and the second-type light emitting layer 202. The third metal layer 301 is disposed between the second type light emitting layer 202 and the third type light emitting layer 302 .

[0065] 35 is a flowchart showing details of step S701 in FIG. 29 according to one embodiment of the present disclosure. Referring to FIG. 35 in combination with FIG. 30, step S701 further includes the following steps. Note that structures formed in steps S801 to S809 of this embodiment are not shown. However, steps S801 to S809 of this embodiment can be understood by those skilled in the art with reference to steps S101 to S109 of the above-described embodiment.

[0066] In step S801, a first metal bonding layer is formed on the substrate 100, a first type light emitting layer 102 is formed on the first base, and a second metal bonding layer is formed on the first type light emitting layer 102.

[0067] More specifically, the first metal bonding layer can be prepared by physical vapor deposition, such as, but not limited to, evaporation or sputtering. The material of the first base is designed according to the first type of light emitting layer 10. For example, the first base can be based on gallium nitride (GaN). The first type of light emitting layer 102 can be fabricated on the first base by, but not limited to, epitaxial growth. The second metal bonding layer can be prepared by physical vapor deposition, such as, but not limited to, evaporation.

[0068] In step S802, the first base is turned upside down so that the second metal bonding layer faces the first metal bonding layer, and the second metal bonding layer is bonded to the first metal bonding layer to form first metal layer 101.

[0069] In step S803, the first base is removed.

[0070] Here, after the first base is removed, step S803 may further include thinning the first-type light emitting layer 102. Furthermore, referring to FIG. 36 , after the first base is removed or the first-type light emitting layer 102 is thinned and before the third metal bonding layer is formed, step S803 may further include forming a microgap structure 06 in the first-type light emitting layer 102. The microgap structure 06 is formed by, but is not limited to, photolithography and etching. In photolithography, a lithography pattern is designed according to the dimensions of the microgap structure 06. According to one embodiment, the cross-sectional dimension of the microgap structure pattern is 2 nm or less.

[0071] In step S804, a third metal bonding layer is formed on the first type light emitting layer 102, a second type light emitting layer 202 is formed on the second base, and a fourth metal bonding layer is formed on the second type light emitting layer 202.

[0072] In step S805, the second base is turned upside down so that the fourth metal bonding layer faces the third metal bonding layer, and then the fourth metal bonding layer is bonded to the third metal bonding layer to form second metal layer 201.

[0073] In step S806, the second base is removed.

[0074] Here, after the second base is removed, step S106 may further include thinning the second-type light emitting layer 202. Furthermore, after the second base is removed or the second-type light emitting layer 202 is thinned, referring to FIG. 36 , step S106 further includes forming a microgap structure 06 in the second-type light emitting layer 202. The microgap structure 06 may be formed using a process similar to the process for forming the microgap structure 06 described above. Therefore, the description of the process for forming the microgap structure 06 will not be repeated.

[0075] In step S807, a fifth metal bonding layer is formed on the second type light emitting layer 202, a third type light emitting layer 302 is formed on the third base, and a sixth metal bonding layer is formed on the third type light emitting layer 302.

[0076] In step S808, the third base is turned upside down so that the sixth metal bonding layer faces the fifth metal bonding layer, and then the sixth metal bonding layer is bonded to the fifth metal bonding layer to form third metal layer 301.

[0077] In step S809, the third base is removed.

[0078] Here, after the third base is removed, step S109 may further include thinning the third type light emitting layer 302. Furthermore, after the third base is removed or the third type light emitting layer 302 is thinned, referring to FIG. 36 , step S109 further includes forming a microgap structure 06 in the third type light emitting layer 302. The microgap structure 06 may be formed using a process similar to the process for forming the microgap structure 06 described above. Therefore, the description of the process for forming the microgap structure 06 will not be repeated.

[0079] FIG. 36 shows microgap structures 06 in the first type light emitting layer 102, the second type light emitting layer 202, and the third type light emitting layer 302.

[0080] Referring again to Figures 30-34, the process after step S701 is further described below.

[0081] In step S702, referring to FIG. 31 , the third type light emitting layer 302 and the third metal layer 301 are patterned until a portion of the top of the second type light emitting layer 202 is exposed, thereby forming a step structure created by the third type light emitting layer 302 on the second type light emitting layer 202.

[0082] More specifically, the step structure includes a third-type light emitting layer 302 and a third metal layer 301. The process of patterning the third-type light emitting layer 302 and the third metal layer 301 also includes over-etching the top of the first-type light emitting layer 102.

[0083] In step S703, referring to FIG. 32, the second type light emitting layer 202 and the second metal layer 201 are further patterned until a portion of the top of the first type light emitting layer 202 is exposed, thereby forming a step structure created by the second type light emitting layer 202 on the first type light emitting layer 102.

[0084] More specifically, a step structure is created by the second-type light emitting layer 202 and the second metal layer 201. The patterning process can be performed by photolithography and plasma etching. The process of patterning the second-type light emitting layer 202 and the second metal layer 201 also includes over-etching the top of the first-type light emitting layer 102. The parameters of the patterning process can be set according to actual needs and are not limited herein.

[0085] In step S704, referring to FIG. 33 , the first metal layer 101 in the first type light emitting region A01 is separated from the first metal layer 101 in the second type light emitting region A02, and from the first type light emitting layer 102 in the third type light emitting region A03, so as to segment the first type light emitting layer 102 in the first type light emitting region A01 from the first type light emitting layer 102 in the second type light emitting region A02 and from the first type light emitting layer 102 in the third type light emitting region A03, according to the preset first type light emitting region A01, the preset second type light emitting region A02, and the preset third type light emitting region A03. and etching third type light emitting layer 302, third metal layer 301, second type light emitting layer 202, second metal layer 201, first type light emitting layer 102, and first metal layer 101 so as to segment second type light emitting layer 202 in second type light emitting region A02 from first type light emitting layer 101 in third type light emitting region A03, so as to segment second type light emitting layer 202 in second type light emitting region A02 from second type light emitting layer 202 in third type light emitting region A03, and so as to segment second metal layer 201 in second type light emitting region A02 from second metal layer 201 in third type light emitting region A03. As a result of step S704, a first type LED01 is formed, the first type LED01 including a first segment 101-1 of the first metal layer and a first segment 102-1 of the first type light emitting layer; a second type LED02 including a second segment 101-2 of the first metal layer, a second segment 102-2 of the first type light emitting layer, a first segment 201-1 of the second metal layer, and a first segment 202-1 of the second type light emitting layer; and a third type LED03 including a third segment 101-3 of the first metal layer, a third segment 102-3 of the first type light emitting layer, a second segment 201-2 of the second metal layer, a second segment 202-2 of the second type light emitting layer, a first segment 301-1 of the third metal layer, and a first segment 302-1 of the third type light emitting layer.

[0086] Here, the etching process is carried out by photolithography and etching process, the parameters of which can be set according to actual needs.

[0087] According to one embodiment, as a result of step S704, the plurality of multicolor light-emitting pixel units are segmented from each other according to a preset pixel unit array. Thus, the pixel units and / or the light-emitting transistors in the array of pixel units can be prepared by one segmentation step, which simplifies the process, reduces manufacturing costs, and facilitates large-scale manufacturing in particular.

[0088] In step S705, referring to FIG. 34, a shared upper electrode layer 05, which functions as an extraction electrode for the first segment 201-1 of the second metal layer and an extraction electrode for the first segment 302-1 of the third metal layer, is formed on the top of the first segment 102-1 of the first type light emitting layer, the first segment 202-1 of the second type light emitting layer, and the first segment 301-1 of the third type light emitting layer.

[0089] Figure 37 is a flowchart showing details of step S705 of Figure 29 according to one embodiment of the present disclosure. Figures 38 to 40 are cross-sectional views showing the structure formed in the step of Figure 37. Referring to Figure 37, step S705 further includes the following steps.

[0090] In step S501, referring to FIG. 38, a portion of the first segment 302-1 of the third type light emitting layer and a portion of the first segment 202-1 of the second type light emitting layer are removed so that a portion of the first segment 201-1 of the second metal layer and a portion of the first segment 301-1 of the third metal layer are exposed.

[0091] In step S502, referring to FIG. 39, in the second type light emitting region A02, a first electrical connector 203 is formed on the sidewalls and top of the first segment 201-1 of the second metal layer, the sidewalls of the second segment 102-2 of the first type light emitting layer, and the sidewalls of the second segment 101-2 of the first metal layer, and in the third type light emitting region A03, a second electrical connector 303 is formed on the top and sidewalls of the first segment 301-1 of the third metal layer, the sidewalls of the second segment 202-2 of the second type light emitting layer, the sidewalls of the second segment 201-2 of the second metal layer, the sidewalls of the third segment 102-3 of the first type light emitting layer, and the sidewalls of the third segment 101-3 of the first metal layer.

[0092] 39, the process for manufacturing the first electrical connector 203 and the second electrical connector 303 further includes the following steps: Although the following steps S5021 to S5023 are not illustrated, it should be noted that steps S5021 to S5023 can be understood by those skilled in the art with reference to steps S4021 to S4023 in the above-described embodiment.

[0093] In step S5021, a mask is formed on the substrate 100 to shield areas without the first electrical connector 203 and the second electrical connector 303, thereby exposing the top and sidewalls of the first segment 201-1 of the second metal layer, the sidewalls of the second segment 102-2 of the first type light emitting layer, and the sidewalls of the second segment 101-2 of the first metal layer in the second type light emitting region A02, and the top and sidewalls of the first segment 301-1 of the third metal layer, the sidewalls of the second segment 202-2 of the second type light emitting layer, the sidewalls of the second segment 201-2 of the second metal layer, the sidewalls of the third segment 102-3 of the first type light emitting layer, and the sidewalls of the third segment 101-3 of the first metal layer in the third type light emitting region A03.

[0094] In step S5022, after step S5021 is completed, a conductive material is deposited on the substrate 100.

[0095] In step S5023, referring to FIG. 39, the mask and the conductive material on the mask are removed so that in the second type light emitting region A02, a first electrical connector 203 is formed on the top and sidewalls of the first segment 201-1 of the second metal layer, the sidewalls of the second segment 102-2 of the first type light emitting layer, and the sidewalls of the second segment 101-2 of the first metal layer, and in the third type light emitting region A03, a second electrical connector 303 is formed on the top and sidewalls of the first segment 301-1 of the third metal layer, the sidewalls of the second segment 202-2 of the second type light emitting layer, the sidewalls of the second segment 201-2 of the second metal layer, the sidewalls of the third segment 102-3 of the first type light emitting layer, and the sidewalls of the third segment 101-3 of the first metal layer.

[0096] The process for fabricating the shared top electrode layer 05 is further described below.

[0097] 40, in step S503, an isolation layer 04 is formed to cover the first type light emitting region A01, the second type light emitting region A02, the third type light emitting region A03, and the surface of exposed substrate 100. The isolation layer 04 has openings on the first segment 102-1 of the first type light emitting layer, the first segment 202-1 of the second type light emitting layer, and the first segment 302-1 of the third type light emitting layer.

[0098] 34 , in step S504, after step S503, a continuous shared top electrode layer 05 is formed over the entire substrate 100. The shared top electrode layer 05 deposited in the openings is connected to the first segment of the first type light emitting layer 102-1, the first segment of the second type light emitting layer 202-1, and the first segment of the third type light emitting layer 302.

[0099] As described above, in the method for fabricating a multicolor light-emitting pixel unit according to an embodiment of the present disclosure, the film deposition processes for all types of LEDs can be performed simultaneously, allowing the LEDs to be prepared simultaneously without having to be prepared separately. This simplifies the process for fabricating multicolor light-emitting pixel units and micro LED display panels and facilitates large-scale production. As a result of the fabrication method according to an embodiment of the present disclosure, different types of LEDs are arranged side by side on the same substrate at short distances from each other. This reduces the size of the LEDs and the display panel made from them. For example, each LED may measure 40 μm × 40 μm. Furthermore, the tops of the different types of LEDs are not on the same horizontal plane. That is, the heights of the different types of LEDs are not the same to expose different types of light-emitting layers at the top of the different types of LEDs. This ensures a sufficient light-emitting area, improves the emission efficiency of all LEDs, and improves the integration of various LEDs. The micro LED display panel formed using the pixel unit according to an embodiment of the present disclosure exhibits clear image display and high resolution. Furthermore, in the Mth type LED, the upper light-emitting layer (the Mth type light-emitting layer) can emit light because an electrical connector connects all metal layers. However, the other light-emitting layers in the Mth type LED are short-circuited because the metal layers on either side of each of the other light-emitting layers are electrically connected to each other. For example, in the Mth type LED, the first type light-emitting layer is short-circuited because the first type metal layers and the second type metal layers on either side of the first type light-emitting layer are electrically connected to each other. The second type light-emitting layer is short-circuited because the second type metal layers and the third type metal layers on either side of the second type light-emitting layer are electrically connected to each other, and so on. Therefore, the various types of LEDs emit light separately without affecting each other. Furthermore, the microgaps in the light-emitting layers can relieve stress within the light-emitting layers, preventing warping without affecting the light-emitting efficiency of the light-emitting layers, thereby improving product yield.

[0100] FIG. 41 is a flowchart illustrating a method of manufacturing a micro LED display panel according to one embodiment of the present disclosure.

[0101] 42, which is a cross-sectional view showing the structure formed in step S4101, a stack structure including, in bottom-to-top order, a first metal layer 101, a first-type light emitting layer 102, a second metal layer 201, and a second-type light emitting layer 202 is formed on wafer substrate 500 in step S4101. The process of forming the stack structure on wafer substrate 500 is similar to the process of forming the stack structure on substrate 100 described with reference to FIGS. 11 to 21. Therefore, a detailed description of step S4101 will not be repeated.

[0102] In step S4102, referring to FIG. 43 which is a cross-sectional view illustrating the structure formed in step S4102 and FIG. 44 which is a top view illustrating the structure formed in step S4102, trenches 600 are formed in the stack structure. The trenches 600 may be formed by etching from the top of the stack structure toward the bottom of the stack structure until the wafer substrate 500 is exposed. The trenches 600 define a plurality of micro LED display panel regions 550 on the wafer substrate 500. Adjacent micro LED display panel regions 550 are separated from each other by trenches 600 formed therebetween. The plurality of micro LED display panel regions 550 are used to form a plurality of micro LED display panels.

[0103] 45, which shows a portion M of the structure of FIG. 43 and is a cross-sectional view after step S4103 has been performed, the second-type light emitting layer 202 and the second metal layer 201 over the entire wafer substrate 500 are patterned, i.e., selectively etched, until a portion of the top surface of the first-type light emitting layer 102 is exposed, thereby forming a plurality of step structures over the entire wafer substrate 500. The process performed in step S4103 is similar to the process performed in step S602 described with reference to FIG. 8. Therefore, a detailed description of step S4103 will not be repeated. During the etching process of step S4103, stress generated by etching can be released through the trenches 600, thereby preventing warping of the wafer substrate 500 due to the stress.

[0104] 46, which is a cross-sectional view of portion M after step S4104 is performed, the second-type light emitting layer 202, the second metal layer 201, the first-type light emitting layer 102, and the first metal layer 101 on the entire wafer substrate 500 are selectively etched to expose the side surfaces of the first metal layer 101. As a result of performing step S4104, a plurality of first-type LEDs 01 and a plurality of second-type LEDs 02 are formed in each micro LED display panel region 550. Each first-type LED 01 includes a first segment 101-1 of the first metal layer and a first segment 102-1 of the first-type light emitting layer. Each second-type LED 02 includes a second segment 101-2 of the first metal layer, a second segment 102-2 of the first-type light emitting layer, a first segment 201-1 of the second metal layer, and a second segment 202-1 of the second-type light emitting layer. The process performed in step S4104 is similar to the process performed in step S603 described with reference to FIG. 9 . Therefore, a detailed description of step S4104 will not be repeated. During the etching process in step S4104, stress generated by etching can be released through trench 600, thereby preventing warping of wafer substrate 500 due to stress.

[0105] In step S4105, referring to FIG. 47, which is a cross-sectional view showing portion M after step S4105, an electrical connector is formed to electrically connect the second segment 101-2 of the first metal layer and the first segment 201-1 of the second metal layer in each second-type LED 02. Furthermore, in each micro LED display panel region 550, a shared upper electrode layer 05 functioning as an extraction electrode of the second metal layer 201 is formed on the top of the first segment 102-1 of the first-type light emitting layer in the plurality of first-type LEDs 01 and on the first segment 202-1 of the second-type light emitting layer in the plurality of second-type LEDs 02. The process performed in step S4105 is similar to the process performed in step S604 described with reference to FIG. 10 and FIGS. 22 to 28. Therefore, a detailed description of step S4105 will not be repeated.

[0106] In step S4106, referring to FIG. 48, which is a top view illustrating the structure formed in step S4106, the wafer substrate 500 having the structure formed in steps S4101-S4105 is cut through the wafer substrate 500 along the trenches 600 shown in FIG. 44, thereby forming a plurality of micro LED display panels 650.

[0107] As described above, in the method for manufacturing a micro LED display panel according to an embodiment of the present disclosure, a trench is formed in the stack structure before the stack structure is etched. Therefore, stress generated during the etching process of the stack structure can be released through the trench, thereby preventing warping of the wafer substrate due to stress. As a result, the quality of the micro LED display panel can be improved.

[0108] While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. 1. A method for manufacturing a micro light emitting diode (LED) display panel, comprising: forming a stack structure on a wafer substrate, the stack structure comprising, in bottom-to-top order, a first metal layer, a first type of light emitting layer, a second metal layer, and a second type of light emitting layer; forming a plurality of trenches in the stack structure, the plurality of trenches defining a plurality of micro LED display panel regions; patterning the second-type light emitting layer and the second metal layer until a portion of a top surface of the first-type light emitting layer is exposed; forming a plurality of first LEDs and a plurality of second LEDs in each of the micro LED display panel regions by patterning the second-type light emitting layer and the second metal layer, and then selectively etching the stack structure to expose side surfaces of the first metal layer, wherein each of the first LEDs includes the first metal layer and the first-type light emitting layer, and each of the second LEDs includes the first metal layer, the first-type light emitting layer, the second metal layer, and the second-type light emitting layer; cutting the wafer substrate to form a plurality of micro LED display panels; A method comprising:

2. forming the stack structure on the wafer substrate; sequentially forming the first metal layer and the first-type light emitting layer on the wafer substrate; forming a first metal bonding layer on the first-type light emitting layer; forming the second-type light emitting layer and a second metal bonding layer on a first base from below to above the first base; bonding the first metal bonding layer and the second metal bonding layer to form the second metal layer; removing the first base; The method of claim 1 , comprising:

3. forming the first metal layer and the first-type light emitting layer on the wafer substrate from bottom to top; forming a third metal bonding layer on the wafer substrate; forming the first-type light emitting layer and a fourth metal bonding layer on a second base from below the first base to above the first base; bonding the third metal bonding layer and the fourth metal bonding layer to form the first metal layer; removing the second base; The method of claim 2 , comprising:

4. thinning the first-type light-emitting layer before forming the first metal bonding layer on the first-type light-emitting layer; The method of claim 2 further comprising:

5. thinning the second type of light emitting layer; The method of claim 2 further comprising:

6. forming a microgap structure in at least one of the first type light emitting layer or the second type light emitting layer; The method of claim 2 further comprising:

7. forming a microgap structure in both the first type light emitting layer and the second type light emitting layer; further comprising The method of claim 2 , wherein the microgap structures in the first type of light emitting layer are staggered relative to the microgap structures in the second type of light emitting layer.

8. electrically connecting the first metal layer and the second metal layer in at least one of the second LEDs; The method of claim 1 further comprising:

9. electrically connecting the first metal layer and the second metal layer in at least one of the second LEDs; removing a portion of the second type light emitting layer in the second LED to expose an upper portion of the second metal layer in the second LED; forming electrical connectors on the exposed top and sidewalls of the second metal layer in the second LED and on the sidewalls of the first-type light emitting layer and the first metal layer in the second LED; The method of claim 8, comprising:

10. forming a top electrode layer over at least one first LED and at least one second LED in each micro LED display panel region; The method of claim 1 further comprising:

11. forming an isolation layer covering the at least one first LED and the at least one second LED; forming a first opening and a second opening in the isolation layer, the first opening exposing a portion of the first type of light emitting layer in the first LED, and the second opening exposing a portion of the second type of light emitting layer in the second LED; forming the top electrode layer on the wafer substrate, the top electrode layer contacting the first type light emitting layer in the first LED through the first opening and contacting the second type light emitting layer in the second LED through the second opening; The method of claim 10 further comprising:

12. the stack structure further comprises a third metal layer formed on the second type light emitting layer, and a third type light emitting layer formed on the third metal layer; the method further comprising patterning the third-type light-emitting layer and the third metal layer until a portion of the second-type light-emitting layer is exposed; and 2. The method of claim 1, wherein selectively etching the stack structure further comprises selectively etching the stack structure to form the plurality of first LEDs, the plurality of second LEDs, and a plurality of third LEDs, each third LED including the first metal layer, the first type light emitting layer, the second metal layer, the second type light emitting layer, the third metal layer, and the third type light emitting layer.

13. forming the stack structure on the wafer substrate; forming the first metal layer, the first type light emitting layer, the second metal layer, and the second type light emitting layer on a wafer substrate from bottom to top; forming a first metal bonding layer on the second-type light emitting layer; forming the third-type light emitting layer and the second metal bonding layer on a base from below to above the base; bonding the first metal bonding layer and the second metal layer to form the third metal layer; removing the base; 13. The method of claim 12, comprising:

14. thinning at least one of the first type light emitting layer, the second type light emitting layer, or the third type light emitting layer; The method of claim 12 further comprising:

15. forming a microgap structure in at least one of the first type light emitting layer, the second type light emitting layer, or the third type light emitting layer; The method of claim 12 further comprising:

16. forming a microgap structure in all of the first type light emitting layer, the second type light emitting layer, and the third type light emitting layer; further comprising the microgap structures in the first type of light emitting layer are staggered relative to the microgap structures in the second type of light emitting layer; and The method of claim 12 , wherein the microgap structures in the second type of light emitting layer are staggered relative to the microgap structures in the third type of light emitting layer.

17. electrically connecting the first metal layer and the second metal layer in at least one of the second LEDs, and electrically connecting the first metal layer, the second metal layer, and the third metal layer in each third LED; The method of claim 12 further comprising:

18. electrically connecting the first metal layer and the second metal layer in at least one of the second LEDs, and electrically connecting the first metal layer, the second metal layer, and the third metal layer in at least one of the third LEDs; removing a portion of the second-type light emitting layer in the second LED to expose an upper portion of the second metal layer in the second LED; removing a portion of the third-type light emitting layer in the third LED to expose an upper portion of the third metal layer in the third LED; forming a first electrical connector on the exposed top and sidewalls of the second metal layer in the second LED and on sidewalls of the first-type light emitting layer and the first metal layer in the second LED; forming a second electrical connector on the exposed top and sidewalls of the third metal layer in the third LED and on sidewalls of the second-type light emitting layer, the second metal layer, the first-type light emitting layer, and the first metal layer in the third LED; 18. The method of claim 17, comprising:

19. forming a top electrode layer over the at least one first LED, the at least one second LED, and the at least one third LED in each micro LED display panel region; The method of claim 12 further comprising:

20. forming an isolation layer covering the at least one first LED, the at least one second LED, and the at least one third LED; forming a first opening, a second opening, and a third opening in the separation layer, the first opening exposing a portion of the first type light emitting layer in the first LED, the second opening exposing a portion of the second type light emitting layer in the second LED, and the third opening exposing a portion of the third type light emitting layer in the third LED; forming the top electrode layer on the wafer substrate, the top electrode layer contacting the first type light emitting layer in the first LED through the first opening, the second type light emitting layer in the second LED through the second opening, and the third type light emitting layer in the third LED through the third opening; 20. The method of claim 19, further comprising:

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