US-12628468-B2 - Method of manufacturing micro-light emitting diode and method of manufacturing display apparatus by using the same

Abstract

Provided are a method of manufacturing a micro-LED and a method of manufacturing a display apparatus to which the method is applied. In the method of manufacturing a micro-LED, a membrane formed to include a cavity is formed on a substrate, and then, a sacrificial layer that may be selectively removed by wet etching is formed on the membrane. Next, a light-emitting device is formed on the sacrificial layer, and the light-emitting device is separated from the membrane by the wet etching. In an example, an undoped semiconductor layer may further be formed between the membrane and the sacrificial layer. The sacrificial layer may include an oxide layer having the same crystal lattice structure as that of the undoped semiconductor layer. In an example, another undoped semiconductor layer may further be formed between the sacrificial layer and the light-emitting device.

Inventors

• Dongho Kim
• Howon Jang
• JEHONG OH
• KyungWook HWANG
• Junsik Hwang

Assignees

• SAMSUNG ELECTRONICS CO., LTD.
• SEOUL NATIONAL UNIVERSITY R&DB FOUNDATION

Dates

Publication Date

20260512

Application Date

20230627

Priority Date

20220627

Claims (20)

1. 1 . A method of manufacturing a light-emitting diode (LED) device, the method comprising: forming, on a substrate, a membrane formed to include a cavity; forming an undoped semiconductor layer on the membrane; forming a sacrificial layer on the undoped semiconductor layer, the sacrificial layer to be selectively removed by wet etching; forming a LED device on the sacrificial layer; and separating the LED device from the undoped semiconductor layer by the wet etching.
2. 2 . The method of claim 1 , wherein the undoped semiconductor layer comprises an undoped GaN layer.
3. 3 . The method of claim 2 , wherein the sacrificial layer comprises an oxide layer having the same crystal lattice structure as that of the undoped semiconductor layer.
4. 4 . The method of claim 1 , further comprising forming another undoped semiconductor layer between the sacrificial layer and the LED device.
5. 5 . The method of claim 1 , wherein the LED device is directly formed on the sacrificial layer.
6. 6 . The method of claim 1 , wherein a plurality of membranes are formed on the substrate, and the undoped semiconductor layer is formed on the plurality of membranes.
7. 7 . The method of claim 6 , wherein the forming of the undoped semiconductor layer on the plurality of membranes comprises: forming, on each of the plurality of membranes, first material layers to be the undoped semiconductor layer; and coalescing the first material layers with each other by growing the first material layers in a lateral direction.
8. 8 . The method of claim 1 , wherein the sacrificial layer comprises a material having a hexagonal wurtzite lattice structure.
9. 9 . The method of claim 1 , wherein HCl, NH 4 Cl or H 3 PO 3 is used as an etching solution in the wet etching.
10. 10 . The method of claim 1 , wherein a surface roughness of the surface separated from the sacrificial layer of the separated LED device is in a range from about 1.5 nm to about 2.5 nm.
11. 11 . The method of claim 1 , wherein the sacrificial layer is formed by using a pulsed laser deposition (PLD) method, an atomic layer deposition (ALD) method, or a molecular beam epitaxy (MBE) method.
12. 12 . The method of claim 1 , wherein the step of forming of the membrane formed to include a cavity on the substrate comprises: forming a sacrificial layer pattern on the substrate; forming a membrane material layer covering the sacrificial layer pattern on the substrate; forming the cavity by removing the sacrificial layer pattern; and crystallizing the membrane material layer.
13. 13 . The method of claim 1 , wherein the step of forming of the LED device on the sacrificial layer comprises: forming a first semiconductor layer on the sacrificial layer; forming an active layer on a partial region of one surface of the first semiconductor layer; forming a second semiconductor layer on the active layer; and forming a first electrode connected to the first semiconductor layer and a second electrode connected to the second semiconductor layer, wherein both of the first electrode and second electrode are formed on one side of the first semiconductor layer, which is opposite to the sacrificial layer.
14. 14 . The method of claim 1 , wherein the LED device comprises a gallium nitride-based LED.
15. 15 . A method of manufacturing a display apparatus, the method comprising: forming a LED by using the method of claim 1 ; and transferring the formed LED to a pixel region of a display panel.
16. 16 . The method of claim 15 , wherein the LED is transferred by using a fluid self-assembly method.
17. 17 . The method of claim 16 , wherein the fluid self-assembly method comprises: stirring the formed LED with a liquid; dropping the liquid including the LED into grooves of a transfer substrate having a plurality of grooves formed in a surface; and arranging the LED dropped into the grooves.
18. 18 . A structure comprising a light-emitting device (LED), the structure comprising: a substrate on which a membrane formed to include a cavity is formed; an undoped semiconductor layer formed on the membrane; a sacrificial layer formed on the undoped semiconductor layer; and a light-emitting device layer formed on the sacrificial layer, wherein the light-emitting device layer comprises: a first semiconductor layer; an active layer formed on the first semiconductor layer; a second semiconductor layer formed on the active layer; a first electrode layer connected to the first semiconductor layer; and a second electrode layer connected to the second semiconductor layer, wherein both of the first electrode layer and second electrode layer are provided on one side that is opposite to the sacrificial layer.
19. 19 . The structure of claim 18 , wherein the undoped semiconductor layer comprises an undoped GaN layer.
20. 20 . The structure of claim 18 , wherein the light-emitting device layer comprises a gallium nitride-based LED.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is based on and claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2022-0078349, filed on Jun. 27, 2022, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety. BACKGROUND 1. Field Example embodiments of the present disclosure relate to light-emitting diode (LED) devices, and more particularly, to methods of manufacturing a LED (such as a micro-LED) and methods of manufacturing a display apparatus including the LED. 2. Description of Related Art A liquid crystal display (LCD) and an organic light-emitting diode (OLED) display are widely used as display apparatuses. Recently, technology for manufacturing a high-resolution display apparatus using the LED (such as a micro LED) has been in the spotlight. Hereinafter, a micro-LED is discussed as an example of the LED. Various methods of manufacturing a micro-LED have been proposed, and various methods for efficient transfer of the micro-LED are being sought. SUMMARY One or more example embodiments provide methods of manufacturing a light-emitting diode (LED) device (e.g., a micro LED device) capable of reducing manufacturing cost or a LED that enables more effective transfer of the LED. One or more example embodiments provide methods of manufacturing a display apparatus that reduces manufacturing cost and time by using the method of manufacturing a LED. Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the example embodiments of the disclosure. According to an aspect of an example embodiment, there is provided a method of manufacturing a LED device (e.g., a micro LED device), the method including forming, on a substrate, a membrane (e.g., a nano-membrane) formed to include a cavity, forming a first undoped semiconductor layer on the membrane, and forming a sacrificial layer that may be selectively removed by wet etching on the first undoped semiconductor layer. Next, a light-emitting device may be formed on the sacrificial layer, and the light-emitting device may be separated from the first undoped semiconductor layer by wet etching. The sacrificial layer may include an oxide layer having the same crystal lattice structure as that of the first undoped semiconductor layer. A second undoped semiconductor layer may further be formed between the sacrificial layer and the light-emitting device. The light-emitting device may be directly formed on the sacrificial layer. A plurality of membranes may be formed on the substrate, and the first undoped semiconductor layer may be formed on the plurality of membranes. The forming of the first undoped semiconductor layer on the plurality of membrane may include forming, on each of the plurality of membranes, first material layers to be the first undoped semiconductor layer, and coalescing the first material layers with each other by growing the first material layers in a lateral direction. The sacrificial layer may include a material having a hexagonal wurtzite lattice structure. The sacrificial layer may include ZnO. HCl, NH4Cl or H3PO3 may be used as the etching solution in the wet etching. A surface roughness of the surface separated from the sacrificial layer of the separated light-emitting device may be in a range from about 1.5 nm to about 2.5 nm. The step of forming of the membrane including a cavity on the substrate may include forming a sacrificial layer pattern on the substrate, forming a membrane material layer covering the sacrificial layer pattern on the substrate, forming the cavity by removing the sacrificial layer pattern, and crystallizing the membrane material layer. The step of forming of a light-emitting device on the sacrificial layer may include forming a first semiconductor layer on the sacrificial layer, forming an active layer on a partial region of one surface of the first semiconductor layer, forming a second semiconductor layer on the active layer, and forming a first electrode connected to the first semiconductor layer and a second electrode connected to the second semiconductor layer. Both of the first and second electrodes may be formed on one side of the first semiconductor layer, which is opposite to the sacrificial layer. According to another aspect of an example embodiment, there is provided a method of manufacturing a display apparatus, the method including forming a LED by using a method of manufacturing a LED according to an embodiment, and transferring the formed LED to a pixel region of a display panel. The LED may be transferred by using a fluid self-assembly method. The fluid self-assembly method may include stirring the formed LED with a liquid, dropping the liquid including the LED into grooves of a transfer substrate having a plurality of grooves formed in a surface thereof, and arranging the LED dropped into the grooves. Accordi