Multi-color LED pixel unit and micro LED display panel

Abstract

To provide a multi-color light-emitting pixel unit and a microdisplay panel.SOLUTION: A multi-color light-emitting pixel unit (1000) includes a first type of light-emitting transistor formed on a substrate (100) and including, in bottom-to-top order, a first segment (101-1) of a first metal layer and a first segment (102-1) of a first type of light-emitting layer, and a second type of light-emitting transistor formed on the substrate (100) and including, in bottom-to-top order, a second segment (101-2) of the first metal layer, a second segment (102-2) of the first type of light-emitting layer, a first segment (201-1) of a second metal layer, and a first segment (202-1) of a second type of light-emitting layer, and including a first electrical connector (203) connecting the second segment (101-2) of the first metal layer and the first segment (201-1) of the second metal layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Patent Application No. 16 / 567,077, filed September 1, 2019. The above-mentioned application is incorporated herein by reference in its entirety.

[0002] The present disclosure relates generally to the technical field of micro light emitting diodes, and more particularly to multi-color LED pixel units and micro LED display panels. [Background technology]

[0003] A light-emitting diode (LED) is a type of semiconductor diode that can convert electrical energy into light energy. A conventional light-emitting diode contains a PN junction with unidirectional conductivity. Under positive bias, holes flow from the P region to the N region and electrons flow from the N region to the P region, and the combination of electrons in the N region and holes in the P region results in spontaneous emission of excited light. Electrons and holes have different energy states in different semiconductor materials, and therefore the energy produced by the combination of electrons and holes is different. The higher the energy, the shorter the wavelength of the excited light. Thus, LEDs can emit different lights of different wavelengths, from ultraviolet light to infrared light, thereby creating multicolor LEDs.

[0004] Multicolor LEDs that emit white light or light of different colors have wide applications, most of which are in the display field. A conventional LED display panel is formed by assembling single-color LEDs one by one on a substrate. The method of assembling single-color LEDs includes bonding the LEDs by metal wires, or connecting the electrodes of the LEDs with an interconnect layer by a metal bonding process or another process. The process of assembling the LEDs of different colors is not carried out until the process of assembling the single-color LEDs is completed, which makes the process complicated, increases the difficulty of the process, and increases the production cost. In addition, the multicolor display panel fabricated by assembling or forming single LEDs one by one consumes more power and reduces the brightness and color. Summary of the Invention

[0005] According to one aspect of the present disclosure, a multi-color light-emitting pixel unit is provided, the multi-color light-emitting pixel unit includes a first type of light-emitting transistor formed on a substrate, the first type of light-emitting transistor including, in bottom-to-top order, a first segment of a first metal layer and a first segment of a first type of light-emitting layer, and a second type of light-emitting transistor formed on the substrate, the second type of light-emitting layer including, in bottom-to-top order, a second segment of the first metal layer, a second segment of the first type of light-emitting layer, a first segment of a second metal layer, and a first segment of a second type of light-emitting layer, and including a first electrical connector connecting the second segment of the first metal layer and the first segment of the second metal layer.

[0006] According to another aspect of the present disclosure, there is provided a microdisplay panel, the microdisplay panel including the multi-color light-emitting pixel unit described above. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a cross-sectional view illustrating a multi-color light-emitting pixel unit according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a cross-sectional view illustrating a multi-color light-emitting pixel unit according to an embodiment of the present disclosure. [Diagram 3] FIG. 2 is a cross-sectional view illustrating a multi-color light-emitting pixel unit according to an embodiment of the present disclosure. [Figure 4] FIG. 2 illustrates a top view of a multi-color light-emitting pixel unit according to an embodiment of the present disclosure. [Diagram 5] FIG. 2 is a cross-sectional view illustrating a multi-color light-emitting pixel unit according to an embodiment of the present disclosure. [Figure 6] 2 is a flowchart illustrating a method for 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 during 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 during 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 during 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 during the method steps of FIG. 6 according to one embodiment of the present disclosure. [Figure 11] 7 is a flowchart showing details of step S601 of FIG. 6 according to one embodiment of the present disclosure. [Figure 12] 12 is a cross-sectional view illustrating a structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 13] 12 is a cross-sectional view illustrating a structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 14] 12 is a cross-sectional view illustrating a structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 15] 12 is a cross-sectional view illustrating a structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 16] 12 is a cross-sectional view illustrating a structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 17] 12 is a cross-sectional view illustrating a structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 18]12 is a cross-sectional view illustrating a structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 19] 12 is a cross-sectional view illustrating a structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 20] 12 is a cross-sectional view illustrating a structure formed in the step of FIG. 11 according to one embodiment of the present disclosure. [Figure 21] 12 is a cross-sectional view illustrating a 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. [Diagram 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 fabricating 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 fabricating a first electrical connector according to one embodiment of the present disclosure. [Figure 28] FIG. 2 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 for fabricating the multi-color light-emitting pixel unit shown in FIG. 3 according to one embodiment of the present disclosure. [Diagram 30] 30A-30C are cross-sectional views illustrating structures formed during the method steps of FIG. 29 according to one embodiment of the present disclosure. [Diagram 31] 30A-30C are cross-sectional views illustrating structures formed during the method steps of FIG. 29 according to one embodiment of the present disclosure. [Diagram 32]30A-30C are cross-sectional views illustrating structures formed during the method steps of FIG. 29 according to one embodiment of the present disclosure. [Diagram 33] 30A-30C are cross-sectional views illustrating structures formed during the method steps of FIG. 29 according to one embodiment of the present disclosure. [Diagram 34] 30A-30C are cross-sectional views illustrating structures formed during the method steps of FIG. 29 according to one embodiment of the present disclosure. [Diagram 35] 30 is a flowchart showing details of step S701 of FIG. 29 according to one embodiment of the present disclosure. [Diagram 36] 1A-1C are cross-sectional views illustrating 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 showing 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. [Diagram 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. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A further understanding of the present disclosure will be provided by reference in detail to the preferred embodiments of the present invention below. The specific embodiments discussed 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.

[0009] Hereinafter, the present disclosure will be further described according to the embodiments of the present disclosure in conjunction with Figures 1 to 40. It should be pointed out that all the accompanying drawings adopt a very simplified form, and the inaccurate scale is only used to help explain the embodiments of the present disclosure conveniently and clearly.

[0010] The multicolor light-emitting pixel unit disclosed herein includes at least one type of light-emitting transistor or multiple 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 conductive layer and the bottom conductive layer. All of the light-emitting transistors share the same top conductive layer and the same bottom conductive layer. It should be noted that the light-emitting layer can be a single layer or multiple layers. An intermediate layer can be disposed between two of the multiple light-emitting layers of the same light-emitting diode. It is assumed that the multicolor light-emitting pixel unit includes first to Mth types of light-emitting transistors, where M is an integer equal to or greater than 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. A microdisplay panel including a plurality of the above-mentioned pixel units arranged in a matrix is ​​also provided in the present disclosure.

[0011] 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 is, but is not limited to, a transparent conductive layer, and the bottom conductive layer of the light-emitting transistor is, but is not limited to, a metal layer. Hereinafter, LED is 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 another light-emitting transistor according to conventional technical means.

[0012] FIG. 1 is a cross-sectional view showing a multi-color light-emitting pixel unit 1000 according to an embodiment of the present disclosure. Referring to FIG. 1, the multi-color light-emitting pixel unit 1000 includes at least a first type LED01 and a second type LED02 arranged side-by-side on a substrate 100. The top of the first type LED01 and the top of the second type LED02 are not in the same horizontal plane. The type of the first type LED01 is different from the type of the second type LED02. As shown in FIG. 1 herein, the top of the first type LED01 is lower than the top of the second type LED02. According to an embodiment, the first type LED01 is selected from a red LED, a green LED, a blue LED, a yellow LED, an orange LED, or a cyan LED, and the second type LED02 is selected from a green LED, a blue LED, a red LED, a yellow LED, an orange LED, or a cyan LED. In addition, the size of the light-emitting area of ​​the first type LED01 is different from the size of the light-emitting area of ​​the second type LED02. For example, the first type LED01 is a red LED, and the second type LED02 is a green LED, and the size of the light-emitting area of ​​the red LED is different from that of the green LED. Furthermore, according to 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.

[0013] In addition, an insulating structure 07 is disposed between the first type LED and the second type LED. In the embodiment shown in FIG. 1, the insulating structure 07 between the first type LED 01 and the second type LED 02 is an insulating trench. The multi-color 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 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 in bottom-to-top order. The first segment 101-1 of the first metal layer constitutes the bottom conductive layer of the first type LED 01. The second type LED02 includes 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 202-2 of the second type light emitting layer, in bottom-to-top order, 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. The insulating structure 07 insulates the first segment 101-1 of the first metal layer in the first type LED01 from the second segment 101-2 of the first metal layer in the second type LED02. The insulating structure 07 also insulates the first segment 102-1 of the first type light emitting layer in the first type LED01 from the second segment 102-2 of the first type light emitting layer in the second type LED02. In addition, 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 LED02 are electrically connected to each other by a first electrical connector 203. According to an embodiment, the first electrical connector 203 can be attached to and contact a part or the entire sidewall surface of the second type LED02. 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 LED02.Further alternatively, the first electrical connector 203 can be formed as a conductive side arm that is attached to and contacts 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 of the second type LED02 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 LED02, so that the first electrical connector 203 adapts to the surface shape of the sidewall of the second type LED02.

[0014] 1, a top insulating layer 04 and a top transparent conductive layer 05 are disposed on the first segment 102-1 of the first type of light emitting layer in the first type LED 01 and the first segment 202-1 of the second type of light emitting layer in the second type LED 02. The top insulating 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 top insulating layer 04 has openings that expose portions of the top 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 top transparent conductive layer 05 covers the top insulating layer 04 and is formed in the openings in the top insulating 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.

[0015] The substrate 100 is an integrated circuit (IC) substrate. The IC substrate includes an interconnect layer electrically connected with the first segment 101-1 of the first metal layer of the first type LED 01 and the second segment 101-2 of the first metal layer of the second type LED 02. The first electrical connector 203 is connected with the second segment 101-2 of the first metal layer of the second type LED 02, so that the first electrical connector 203 is connected with the interconnect layer of the substrate 100. In addition, referring to FIG. 1, the lower portion of the first electrical connector 203 extends to the substrate 100 and connects with the interconnect layer. In this specification, the IC substrate includes at least a driving circuit. The driving circuit controls all the LEDs separately.

[0016] FIG. 2 is a cross-sectional view showing a multi-color light-emitting pixel unit 2000 according to an embodiment of the present disclosure. Referring to FIG. 2, the multi-color light-emitting pixel unit 2000 includes at least a first type LED01, a second type LED02, and a third type LED03 disposed on the same substrate 100. The third type LED03 is different from the first type LED01 and the second type LED02. Herein, the first type LED01 is selected from a red LED, a green LED, a blue LED, a yellow LED, an orange LED, or a cyan LED, the second type LED02 is selected from a green LED, a blue LED, a red LED, a yellow LED, an orange LED, or a cyan LED, and the third type LED03 is selected from 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. 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, but the height of the second type LED02 is the same as the height of the third type LED03. In other embodiments, the height of the third type LED03, the height of the first type LED01, and the height of the second type LED02 can be different from each other, as shown in FIG.

[0017] 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 of the multi-color light-emitting pixel unit 2000, and therefore the detailed description of the structures is not repeated. The third type LED03 of the multi-color light-emitting pixel unit 2000 includes 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 in the order from bottom to top, and a second electrical connector 303 connects 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 a top insulating layer 04 covering the first type LED01, the second type LED02, and the third type LED03, and having an opening exposing a portion of the first segment 102-1 of the first type light-emitting layer, a portion of the first segment 202-1 of the second type light-emitting layer, and a portion of the first segment 302-1 of the third type light-emitting layer in the first type LED01. A top electrode layer 05 is formed on the top insulating layer 04 and contacts 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 opening in the top insulating layer 04.

[0018] 3 is a cross-sectional view of a multi-color light-emitting pixel unit 3000 according to an 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 second type LED03.

[0019] FIG. 4 is a top view showing a multi-color light-emitting pixel unit 4000 according to an embodiment of the present disclosure. The multi-color light-emitting pixel unit 4000 can be the multi-color light-emitting pixel unit 2000 shown in FIG. 2 or the multi-color light-emitting pixel unit 3000 shown in FIG. 3. Although FIG. 4 shows the arrangement of three types of LEDs 01, 02, and 03 in a pixel unit, the present disclosure also includes other arrangements such as a matrix. Herein, 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 also 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 the light-emitting area of ​​each of the first, second, and third types LED 01, 02, and 03 can be determined according to the color of light required to be emitted from the multi-color 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. As shown in Figure 4, the space between the red LED and the blue LED is larger than that between the blue LED and the green LED, and the space between the red LED and the green LED is larger than that between the blue LED and the green LED, so that a better light-emitting effect is achieved.

[0020] 3, an insulating structure 07 is disposed between two of the first type LED01, the second type LED02, and the third type LED03. The insulating structure is an insulating trench. The first type LED01, the second type LED02, and the third type LED03 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 LED01 and the second type LED02 in FIG. 3 are the same as the first type LED01 and the second type LED02 in FIG. 2. Specifically, as shown in FIG. 3, the first type LED01 includes 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 in bottom-to-top order. The second type LED02 includes at least, from bottom to top, a second segment 101-2 of the first metal layer, a second segment 102-2 of the first type of light emitting layer, a first segment 201-1 of the second metal layer, and a first segment 202-1 of the second type of light emitting layer, and a first electrical connector 203. The third type LED03 includes at least, from bottom to top, a third segment 101-3 of the first metal layer, a third segment 102-3 of the first type of light emitting layer, a second segment 201-2 of the second metal layer, a second segment 202-2 of the second type of light emitting layer, a first segment 301-1 of the third metal layer, and a first segment 302-1 of the third type of 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 with 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 with the second segment 201-2 of the second metal layer and the third segment 101-3 of the first metal layer.The insulating structure 07 insulates 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 insulates 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 insulated 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 insulated 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 of light-emitting layer in the second type LED 02 with the second segment 101-2 of the first metal layer, and the second electrical connector 303 is used to connect the second segment 202-2 of the second type of light-emitting layer and the third segment 102-3 of the first type of light-emitting layer in the third type LED 03 with the third segment 101-3 of the first metal layer. Therefore, in order to simplify the manufacturing process, the first electrical connector 203 also connects the second segment 102-2 of the first type of light-emitting layer with the second segment 101-2 of the first metal layer in the same manner as in FIG. 1 . 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. 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. In addition, the lower part of the first electrical connector 203 and the lower part of the second electrical connector 303 directly contact the substrate 100 separately, which simplifies the manufacturing process. It should be noted that the material of the first electrical connector 203 and the second electrical connector 303 is formed 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.

[0021] In one embodiment, the first type of light-emitting layer is a red light-emitting layer, the second type of light-emitting layer is a green light-emitting layer, and the third type of light-emitting layer is a blue light-emitting layer, and the first type of LED01 is a red LED01, the second type of LED02 is a green LED02, and the third type of 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. As a result, the first segment 102-1 of the red light-emitting layer in the red LED01 emits red light. In the green LED02, the first electrical connector 203 electrically connects the second segment 102-2 of the red light-emitting layer with the second segment 101-2 of the first metal layer, so that the voltage applied between the top 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. As a result, only the first segment 202-1 of the green light-emitting layer in the green LED02 emits green light, and the second segment 102-2 of the red light-emitting layer in the green LED02 does not emit light. In the third type LED03, the second electrical connector 303 electrically connects the third segment 102-3 of the red light emitting layer and the second segment 202-2 of the green light emitting layer with the third segment 101-3 of the first metal layer, so that the voltage applied between the top transparent conductive layer 05 and the third segment 101-3 of the first metal layer is applied only to the first segment 302-1 of the blue light emitting layer. As a result, only the first segment 302-1 of the blue light emitting layer in the blue LED03 emits blue light, and the third segment 102-3 of the red light emitting layer and the second segment 202-2 of the green light emitting layer in the blue LED03 do not emit light.

[0022] 3, a top insulating layer 04 and a top transparent conductive layer 05 are disposed over the first type LEDs 01, the second type LEDs 02, and the third type LEDs 03. The top insulating layer 04 covers the first segment of the first type light emitting layer 102-1, the first segment of the second type light emitting layer 202-1, the first segment of the third type light emitting layer 302-1, and the exposed substrate 100. Openings are disposed in the top insulating layer 04 to expose portions of the top surfaces of 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 302-1. The top transparent conductive layer 05 covers the top insulating layer 04 and is formed in the openings of the top insulating layer 04, thereby contacting the exposed upper surface of the first segment 102-1 of the first type of light-emitting layer, the exposed upper surface of the first segment 202-1 of the second type of light-emitting layer, and the exposed upper surface of the first segment 302-1 of the third type of light-emitting layer.

[0023] The 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. It should be noted that the interconnect layer of the IC substrate 100 is electrically connected to the first type LED01, the second type LED02, and the third type LED03. The driving circuit of the IC substrate 100 controls all the LEDs separately.

[0024] In the multi-color light-emitting pixel units 1000-4000 of Figures 1-4, one or more of the light-emitting layers 102, 202, and 302 can have a microgap structure. For example, in the multi-color light-emitting pixel unit 1000 shown in Figure 1, 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 both the first type light-emitting layer 102 and the second type light-emitting layer 202 can have a microgap structure. As another example, in the multi-color light-emitting pixel unit 3000 shown in FIG. 3, the first type light-emitting layer 102 can have a micro-gap structure, or the second type light-emitting layer 202 can have a micro-gap structure, or the third type light-emitting layer 302 can have a micro-gap structure, or both the first type light-emitting layer 102 and the second type light-emitting layer 202 can have a micro-gap structure, or both the second type light-emitting layer 202 and the third type light-emitting layer 302 can have a micro-gap structure, or both the first type light-emitting layer 102 and the third type light-emitting layer 302 can have a micro-gap 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 micro-gap structure. In this specification, each of the micro-gap structures in the multi-color light-emitting pixel units 1000 to 3000 shown in FIG. 1 to FIG. 3 can be, but is not limited to, an air gap. The air gap is sealed. Preferably, the cross-sectional dimension of the air gap is 2 nm or less so as to relieve 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, where the cross-sectional dimension of the air gap can be the cross-sectional diameter of the air gap, or the cross-sectional length or width of the air gap.

[0025] 5 is a cross-sectional view illustrating a multi-color light-emitting pixel unit 5000 according to an embodiment of the present disclosure. As shown in FIG. 5, the first type light-emitting layer 102, the second type light-emitting layer 202, and the third type light-emitting layer 302 can each have multiple micro-gap structures 06. Each micro-gap structure 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 an embodiment, the micro-gap structure 06 is disposed in at least one light-emitting layer, preferably the top light-emitting layer.

[0026] 5, the micro-gap structures 06 are staggered in the multiple light-emitting layers, i.e., the micro-gap structures 06 in the first type light-emitting layer 102 are not vertically aligned with the micro-gap structures 06 in the second type light-emitting layer 202, and the micro-gap structures 06 in the second type light-emitting layer 202 are not vertically aligned with the micro-gap structures 06 in the third type light-emitting layer 302. In the second type LED 02 and the third type LED 03, respectively, the micro-gap structures in the first type light-emitting layer 102 are insulated and sealed between the second metal layer 201 above and the first metal layer 101 below the first type light-emitting layer 102. In the third type LED 03, the micro-gap structure 06 in the second type light-emitting layer 202 is insulated and sealed between a third metal layer 301 above the second type light-emitting layer 202 and the underlying second metal layer 201, and the micro-gap structure 06 in the third type light-emitting layer 302 is insulated and sealed between a top insulating layer 04 above the third type light-emitting layer 302 and the underlying third metal layer 301.

[0027] Similarly, in another embodiment of the present disclosure, in a multi-color light-emitting pixel unit including first to Mth type LEDs, the Mth type LED has M light-emitting layers, and a metal layer is disposed below each light-emitting layer, where M is a positive integer equal to or greater than 2. In each of the first to Mth type LEDs, a top conductive layer (as the top conductive layer) is disposed above the top light-emitting layer, so that the micro-gap structure in the top light-emitting layer can be insulated and sealed between the top conductive layer and the metal layer below the top light-emitting layer. The micro-gap structures in all light-emitting layers are insulated and sealed between the metal layers located above and below the associated light-emitting layer, respectively.

[0028] In addition, similar to the multicolor light-emitting pixel units 1000-4000 in Figs. 1-4, the 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 at least all the light-emitting layers and metal layers constructed in the (M-1)th type LED, the Mth light-emitting layer, and the Mth metal layer. Based on the above, the Mth type LED has an (M-1)th electrical connector that connects 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. For the arrangement of the (M-1)th electrical connector, reference can be made to the description of the first electrical connector 203 in Fig. 1. The first through (M-1)th electrical connectors connect the first through Mth metal layers, and the first through (M-1)th electrical connectors can directly contact the substrate and the first metal layer. In this specification, there are differences between the first type LEDs to the Mth type LEDs. In addition, all types of LEDs can be selected from red LEDs, green LEDs, blue LEDs, yellow LEDs, orange LEDs, purple LEDs, or cyan LEDs. In this specification, the different color LEDs are conventional LEDs that may be known to those skilled in the art and are not described herein. Furthermore, the first type LEDs to the Mth type LEDs are spaced apart on the same substrate. A top insulating layer covers the exposed surface of the substrate and the exposed surfaces of the first through Mth types of LEDs. The top insulating layer of all types of LEDs has its own opening, and a transparent conductive layer covers the surface of the top insulating layer and fills the opening, and the transparent conductive layer under the opening electrically contacts the top light emitting layer of all types of LEDs. Referring to FIG. 4 and FIG. 5, in a pixel unit having M types of LEDs, the sizes of the light-emitting 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-emitting area of ​​the first type of LED is larger than the size of the light-emitting area of ​​the other type 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 type of LEDs. Alternatively, the other type of LED includes at least a green LED or a blue LED.

[0029] A multi-color microdisplay panel is also provided according to one embodiment of the present disclosure. The microdisplay panel includes a plurality of multi-color pixel units arranged in a matrix. The multi-color pixel units herein can be the LED pixel units described above.

[0030] The method for fabricating the multi-color light-emitting pixel unit is further described below in combination with the drawings.

[0031] Figure 6 is a flow chart illustrating a method for fabricating a multi-color light-emitting pixel unit as shown in Figure 1 according to one embodiment of the present disclosure. Figures 7-10 are cross-sectional views illustrating a structure formed in the steps illustrated in Figure 6 according to one embodiment of the present disclosure. Referring to Figure 6, the method for fabricating a multi-color light-emitting pixel unit as shown in Figure 1 includes the following steps:

[0032] In step S601, referring to FIG. 7, 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 in a bottom-to-top order. In other words, the first type light emitting layer 102 and the second type light emitting layer 202 are stacked on the substrate 100 in a bottom-to-top order. The first metal layer 101 is formed below the first type light emitting layer 102. The second metal layer 201 is formed below 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 light emitting layer 202.

[0033] More specifically, the substrate 100 can be, but is not limited to, an IC substrate.

[0034] Fig. 11 is a flow chart showing details of step S601 of Fig. 6 according to one embodiment of the present disclosure. Fig. 12-Fig. 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:

[0035] In step S101, referring to FIG. 12, a first metal bonding layer M01 is formed on a substrate 100, a first type light emitting layer 102 is formed on a first base B1, and a second metal bonding layer M02 is formed on the first type light emitting layer 102.

[0036] More specifically, the first metal bonding layer M01 can be made by physical vapor deposition, such as, but not limited to, evaporation, sputtering, etc. 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 M02 can be made by, but not limited to, physical vapor deposition, such as, but not limited to, evaporation.

[0037] In step S102, referring to FIG. 13 in combination with FIG. 12, the first base B1 is inverted 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.

[0038] Referring to FIG. 14 in combination with FIG. 13, in step S103, the first base B1 is removed.

[0039] Herein, after the first base B1 is removed, referring to FIG. 15, step S103 further includes: thinning the first-type light-emitting layer 102.

[0040] In addition, according to an embodiment, after the first base B1 is removed or the first type light emitting layer 102 is thinned, but before the third metal bonding layer is formed, referring to FIG. 16, step S103 may further include forming a micro-gap structure 06 in the first type light emitting layer 102. The micro-gap structure 06 is formed, but not limited to, by photolithography and etching. In photolithography, a lithography pattern is designed according to the dimensions of the micro-gap structure 06. According to an embodiment, the cross-sectional dimension of the micro-gap structure pattern is 2 nm or less. Here, the cross-sectional dimension of the air gap can be the cross-sectional diameter of the air gap, or the cross-sectional length or width of the air gap.

[0041] 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.

[0042] In step S105, referring to FIG. 18 in combination with FIG. 17, the second base B2 is inverted 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.

[0043] In step S106, referring to FIG. 19 in combination with FIG. 18, the second base B2 is removed.

[0044] Herein, after the second base B2 is removed, referring to FIG. 20, in step S106, the second-type light-emitting layer 202 is thinned.

[0045] According to an embodiment, after the second base B2 is removed or the second-type light-emitting layer 202 is thinned, referring to Fig. 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.

[0046] Referring again to FIGS. 6-10, the process after step S601 according to an embodiment of the present disclosure is further described below.

[0047] 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 created by the second-type light-emitting layer 202 on the first-type light-emitting layer 102.

[0048] More specifically, the process of patterning the second-type light-emitting layer 202 and the second metal layer 201 can be 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, which are not limited herein.

[0049] 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 that the first type light-emitting layer 102 in the first type light-emitting region A01 is segmented from the first type light-emitting layer 102 in the second type light-emitting region A02, and the first metal layer 101 in the first type light-emitting region A01 is segmented 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 of 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 of light-emitting layer, a first segment 201-1 of the second metal layer, and a second segment 202-1 of the second type of light-emitting layer.

[0050] In this specification, the process of etching 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.

[0051] According to an embodiment, as a result of step S603, a plurality of multi-color light-emitting pixel units are segmented from each other according to the preset array of pixel units. In this way, the light-emitting transistors in the form of pixel units and / or arrays of pixel units can be made by one segmentation step, which simplifies the process, reduces the production cost, and facilitates large-scale production in particular.

[0052] In step S604, referring to FIG. 10, a shared top 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 in the second type light-emitting area A02.

[0053] Fig. 22 is a flow chart showing details of step S604 of Fig. 6 according to one embodiment of the present disclosure. Fig. 23-25 ​​are cross-sectional views showing a structure formed in the steps 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.

[0054] In step S401, referring to FIG. 23, a portion of the first segment 202-1 of the second-type light-emitting layer is removed to expose a portion of the first segment 201-1 of the second metal layer.

[0055] In step S402, referring to FIG. 24, 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 in the second type light-emitting area A02.

[0056] 26-27 are cross-sectional views showing a structure formed in the steps of fabricating 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:

[0057] In step S4021, referring to FIG. 26 in combination with FIG. 24, a mask Y is formed to mask areas not having 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.

[0058] In step S4022, with reference to FIG. 27, after completing step S4021, a conductive material 203' is deposited on the substrate 100.

[0059] In step S4023, referring again to FIG. 10, mask Y and the conductive material 203' on mask Y are removed so as to form a first electrical connector 203 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 in the second type light-emitting area A02.

[0060] The process for fabricating the shared top electrode layer 05 is further described below.

[0061] 25, in step S403, an insulating layer 04 is formed covering the first type light-emitting region A01, the second type light-emitting region A02, and the exposed surface of the substrate 100. The insulating layer 04 has openings in 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] 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 to the first segments 102-1 of the first type light-emitting layer in the first type light-emitting region A01 and the first segments 202-1 of the second type light-emitting layer in the second type light-emitting region A02.

[0063] FIG. 28 shows a structure of a multi-color light-emitting pixel unit having a micro-gap structure in the first-type light-emitting layer 102 and the second-type light-emitting layer 202 according to one embodiment of the present disclosure.

[0064] Figure 29 is a flow chart illustrating a method of fabricating a multi-color light-emitting pixel unit as 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 illustrated in Figure 6 according to one embodiment of the present disclosure. Referring to Figure 29, a method of fabricating a multi-color light-emitting pixel unit 3000 as shown in Figure 3 includes the following steps.

[0065] In step S701, referring to FIG. 30, a stack structure including 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 is formed on a substrate 100 in a bottom-to-top order. 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 in a bottom-to-top order. The first metal layer 101 is formed below the first type light emitting layer 102. The second metal layer 201 is formed below the second type light emitting layer 202. The third metal layer 301 is formed below 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. A third metal layer 301 is disposed between the second-type light-emitting layer 202 and the third-type light-emitting layer 302 .

[0066] FIG. 35 is a flowchart showing details of step S701 of FIG. 29 according to an embodiment of the present disclosure. With reference to FIG. 35 in combination with FIG. 30, step S701 further includes the following steps. Note that the structures formed in steps S801-S809 of this embodiment are not shown in the drawings. However, steps S801-S809 of this embodiment can be understood by those skilled in the art with reference to steps S101-S109 of the above-mentioned embodiment.

[0067] In step S801, a first metal bonding layer is formed on a substrate 100, a first type light emitting layer 102 is formed on a first base, and a second metal bonding layer is formed on the top of the first type light emitting layer 102.

[0068] More specifically, the first metal bonding layer can be made by physical vapor deposition, such as, but not limited to, evaporation, sputtering, etc. 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 made by, but not limited to, epitaxial growth on the first base. The second metal bonding layer can be made by, but not limited to, physical vapor deposition, such as, but not limited to, evaporation.

[0069] 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 the first metal layer 101.

[0070] In step S803, the first base is removed.

[0071] Herein, after the first base is removed, step S803 may further include thinning the first type light emitting layer 102. In addition, 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, referring to FIG. 36, step S803 may further include forming a microgap structure 06 in the first type light emitting layer 102. The microgap structure 06 is formed, but not limited to, by photolithography and etching. In photolithography, a lithography pattern is designed according to the dimensions of the microgap structure 06. According to an embodiment, the cross-sectional dimension of the microgap structure pattern is 2 nm or less.

[0072] 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 top of the second type light emitting layer 202.

[0073] 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 the second metal layer 201.

[0074] In step S806, the second base is removed.

[0075] Herein, after the second base is removed, step S106 may further include thinning the second type light emitting layer 202. In addition, 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 of forming the microgap structure 06 described above. Therefore, the description of the process of forming the microgap structure 06 will not be repeated.

[0076] 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 top of the third type light emitting layer 302.

[0077] In step S808, the third base is flipped 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 the third metal layer 301.

[0078] In step S809, the third base is removed.

[0079] Herein, after the third base is removed, step S109 may further include thinning the third type light emitting layer 302. In addition, 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 of forming the microgap structure 06 described above. Therefore, the description of the process of forming the microgap structure 06 will not be repeated.

[0080] FIG. 36 shows micro-gap structures in first-type light-emitting layer 102, second-type light-emitting layer 202, and third-type light-emitting layer 302.

[0081] Referring again to FIGS. 30-34, the process after step S701 is further described below.

[0082] 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 topmost part 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.

[0083] 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.

[0084] 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.

[0085] More specifically, the step structure is made by the second-type light-emitting layer 202 and the second metal layer 201. The patterning process can be 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, which are not limited herein.

[0086] In step S704, referring to FIG. 33 , 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, the third-type light-emitting layer 302, the third metal layer 301, 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 to etch the first-type light-emitting layer 102 in the first-type light-emitting region A01 from the first-type light-emitting layer in the second-type light-emitting region A02, and the third-type light-emitting region A03 from the first-type light-emitting layer in the third-type light-emitting region A04. A03, the first metal layer 101 in the first type light-emitting region A01 is segmented from the first metal layer in the second type light-emitting region A02 and from the first metal layer in the third type light-emitting region A03, the second type light-emitting layer 202 in the second type light-emitting region A02 is segmented from the second type light-emitting layer in the third type light-emitting region A03, and the second metal layer 201 in the second type light-emitting region A02 is segmented from the second metal layer in the third type light-emitting region A03. As a result of step S704, a first type LED 01 is formed, the first type LED 01 including the first segment 101-1 of the first metal layer and the first segment 102-1 of the first type light emitting layer, a second type LED 02 including the second segment 101-2 of the first metal layer, the second segment 102-2 of the first type light emitting layer, the first segment 201-1 of the second metal layer, and the first segment 202-1 of the second type light emitting layer, and a third type LED 03 including the third segment 101-3 of the first metal layer, the third segment 102-3 of the first type light emitting layer, the second segment 201-2 of the second metal layer, the second segment 202-2 of the second type light emitting layer, the first segment 301-1 of the third metal layer, and the first segment 302-1 of the third type light emitting layer.

[0087] Herein, the etching process is carried out by photolithography and etching process, the parameters of which can be set according to actual needs.

[0088] According to an embodiment, as a result of step S704, a plurality of multi-color light-emitting pixel units are segmented from each other according to the preset array of pixel units. Thus, the light-emitting transistors in the form of pixel units and / or arrays of pixel units can be made by one segmentation step, which simplifies the process, reduces the production cost, and facilitates large-scale production in particular.

[0089] In step S705, referring to FIG. 34, a shared top 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 301-1 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 302-1 of the third type light-emitting layer.

[0090] Figure 37 is a flow chart showing details of step S705 of Figure 29 according to one embodiment of the present disclosure. Figures 38-40 are cross-sectional views showing the structure formed in the step shown in Figure 37. Referring to Figure 37, step S705 further includes the following steps:

[0091] 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 to expose 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.

[0092] In step S502, referring to FIG. 39, 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 in the second type light-emitting area A02, and 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 in the third type light-emitting area A03.

[0093] 39, the process of manufacturing the first electrical connector 203 and the second electrical connector 303 further includes the following steps: Note that, although the following steps S5021 to S5023 are not shown in the drawings, those skilled in the art can understand steps S5021 to S5023 by referring to steps S4021 to S4023 in the above embodiment.

[0094] In step S5021, a mask is formed on the substrate 100 to shield areas not having the first electrical connector 203 and the second electrical connector 303, thereby exposing, in the second type light-emitting area A02, 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 area A03, 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.

[0095] In step S5022, after step S5021 is completed, a conductive material is deposited on the substrate 100.

[0096] In step S5023, referring to FIG. 39, the mask and the conductive material on the mask are removed to form a first electrical connector 203 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 in the second type light-emitting area A02, and 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 in the third type light-emitting area A03.

[0097] The process for fabricating the shared top electrode layer 05 is further described below.

[0098] 40, in step S503, an insulating layer 04 is formed covering the first type light-emitting region A01, the second type light-emitting region A02, the third type light-emitting region A03, and the exposed surface of the substrate 100. The insulating layer 04 has openings in 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.

[0099] 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 connects to the first segments 102-1 of the first type light-emitting layers, the first segments 202-1 of the second type light-emitting layers, and the first segments 302 of the third type light-emitting layers.

[0100] As described above, in the method of fabricating a multi-color light-emitting pixel unit according to an embodiment of the present disclosure, the deposition process can be performed simultaneously on all types of LEDs, so that the LEDs can be fabricated simultaneously without being fabricated separately, which simplifies the process of fabricating a multi-color light-emitting pixel unit and a micro LED display panel 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 a short distance from each other. Thus, the size of the LEDs and the display panel made of the LEDs can be reduced. For example, the size of each LED can be 40 μm×40 μm. In addition, 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, so that the different types of light-emitting layers are exposed on the tops of the different types of LEDs, thereby ensuring the light-emitting area and improving the light-emitting efficiency of all the LEDs, and improving the integration of various LEDs. The micro LED display panel formed by the pixel unit according to an embodiment of the present disclosure has a clear image display and high resolution. Furthermore, the electrical connector connects all the metal layers in the Mth type LED, so that the Mth type light-emitting layer, which is the top light-emitting layer in the Mth type LED, can emit light, while the metal layers disposed on both sides of each of the other light-emitting layers are electrically connected to each other, so that the other light-emitting layers in the Mth type LED are short-circuited. For example, in the Mth type LED, the first type metal layer and the second type metal layer disposed on both sides of the first type light-emitting layer are electrically connected to each other, so that the first type light-emitting layer is short-circuited, and the second type metal layer and the third type metal layer disposed on both sides of the second type light-emitting layer are electrically connected to each other, so that the second type light-emitting layer is short-circuited, and so on. Thus, the various types of LEDs emit light separately without affecting each other. Furthermore, the micro-gaps in the light-emitting layer can release the internal stress of the light-emitting layer and avoid the warping of the light-emitting layer without any effect on the light-emitting efficiency of the light-emitting layer, thereby improving the product yield.

[0101] While the present invention has been shown and described in detail with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. a first type of light emitting transistor formed on the substrate, the first type of light emitting transistor including, in bottom-to-top order, a first segment of a first metal layer and a first segment of a first type of light emitting layer; a second type of light emitting transistor formed on the substrate, the second type of light emitting transistor including, in bottom-to-top order, a second segment of the first metal layer, a second segment of the first type of light emitting layer, a first segment of a second metal layer, and a first segment of a second type of light emitting layer, and a first electrical connector connecting the second segment of the first metal layer and the first segment of the second metal layer.

2. 10. The multi-color light-emitting pixel unit of claim 1, further comprising a top electrode layer formed over the first type and second type light-emitting transistors.

3. a top insulating layer formed between the top electrode layer and the first type light emitting transistor and between the top electrode layer and the second type light emitting transistor; the top insulating layer includes openings exposing a portion of the first segment of the first type of light emitting layer and a portion of the first segment of the second type of light emitting layer; 3. The multi-color light-emitting pixel unit of claim 2, wherein the top electrode layer contacts the first segments of the first type of light-emitting layer and the first segments of the second type of light-emitting layer through the openings in the top insulating layer.

4. 2. The multi-color light-emitting pixel unit of claim 1, wherein a size of a light-emitting area of ​​the first type light-emitting transistor is different from a size of a light-emitting area of ​​the second type light-emitting transistor.

5. the first type light emitting transistor is a red light emitting transistor; 2. The multi-color light-emitting pixel unit of claim 1, wherein a size of a light-emitting area of ​​the first type light-emitting transistor is larger than a size of a light-emitting area of ​​the second type light-emitting transistor.

6. 10. The multi-color light-emitting pixel unit of claim 1, further comprising a micro-gap structure in at least one of the first type light-emitting layer and the second type light-emitting layer.

7. 10. The multi-color light-emitting pixel unit of claim 1, further comprising a micro-gap structure in both the first type light-emitting layer and the second type light-emitting layer.

8. 8. The multi-color light-emitting pixel unit of claim 7, wherein in the second-type light-emitting transistor, the micro-gap structures in the first segments of the second-type light-emitting layer are interleaved with the micro-gap structures in the second segments of the first-type light-emitting layer.

9. A third type of light emitting transistor, formed on the substrate, a third segment of the first metal layer, a third segment of the first type of light emitting layer, a second segment of the second metal layer, a second segment of the second type of light emitting layer, a first segment of a third metal layer, and a first segment of a third type of light emitting layer, in that order from bottom to top, and a second electrical connector connecting the third segment of the first metal layer, the second segment of the second metal layer, and the first segment of the third metal layer. The multi-color light-emitting pixel unit of claim 1 , further comprising a third type of light-emitting transistor.

10. 10. The multi-color light-emitting pixel unit of claim 9, further comprising a top electrode layer formed over the first type light-emitting transistors, the second type light-emitting transistors, and the third type light-emitting transistors.

11. a top insulating layer formed between the top electrode layer and the first type light emitting transistor, between the top electrode layer and the second type light emitting transistor, and between the top electrode layer and the third type light emitting transistor; the top insulating layer includes openings exposing a portion of the first segment of the first type of light emitting layer, a portion of the first segment of the second type of light emitting layer, and a portion of the first segment of the third type of light emitting layer; 11. The multi-color light-emitting pixel unit of claim 10, wherein the top electrode layer contacts the first segments of the first type of light-emitting layer, the first segments of the second type of light-emitting layer, and the first segments of the third type of light-emitting layer through the openings in the top insulating layer.

12. 10. The multi-color light-emitting pixel unit of claim 9, wherein the first type light-emitting transistor, the second type light-emitting transistor, and the third type light-emitting transistor have light-emitting areas of different sizes from each other.

13. the first type light emitting transistor is a red light emitting transistor; 10. The multi-color light-emitting pixel unit of claim 9, wherein a size of a light-emitting area of ​​the first type light-emitting transistor is larger than a size of a light-emitting area of ​​the second type light-emitting transistor, and the size of the light-emitting area of ​​the second type light-emitting transistor is larger than a size of a light-emitting area of ​​the third type light-emitting transistor.

14. 10. The multi-color light-emitting pixel unit of claim 9, further comprising a micro-gap structure in at least one of the first type light-emitting layer, the second type light-emitting layer, and the third type light-emitting layer.

15. 10. The multi-color light-emitting pixel unit of claim 9, further comprising a micro-gap structure in all of the first type light-emitting layer, the second type light-emitting layer, and the third type light-emitting layer.

16. in the second-type light-emitting transistor, the microgap structures in the first segments of the second-type light-emitting layer are interleaved with the microgap structures in the second segments of the first-type light-emitting layer; 16. The multi-color light-emitting pixel unit of claim 15, wherein in the third-type light-emitting transistor, the microgap structures in the first segments of the third-type light-emitting layer are interleaved with the microgap structures in the second segments of the second-type light-emitting layer, and the microgap structures in the second segments of the second-type light-emitting layer are interleaved with the microgap structures in the third segments of the first-type light-emitting layer.

17. 10. The multi-color light-emitting pixel unit of claim 1, wherein a height of the first type of light-emitting transistor is different from a height of the second type of light-emitting transistor.

18. 2. The multi-color light-emitting pixel unit of claim 1, wherein a height of the first type of light-emitting transistor is different from a height of the second type of light-emitting transistor, and the height of the second type of light-emitting transistor is different from a height of the third type of light-emitting transistor.

19. A microdisplay panel comprising the multi-color light-emitting pixel unit of claim 1.

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