BOTTOM EMISSION MICROLED DISPLAY AND A REPAIR METHOD THEREOF
A bottom emission microLED display includes a microLED disposed above a transparent substrate; a light guiding layer surrounding the microLED to controllably guide light generated by the microLED towards the transparent substrate; and a reflecting layer formed over the light guiding layer to reflect the light generated by the microLED downwards and to confine the light generated by the microLED to prevent the light from leaking upwards or sidewards.
This application claims priority of Taiwan Patent Application No. 106114691, filed on May 3, 2017, the entire contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION 1. Field of the InventionThe present invention generally relates to a micro light-emitting diode (microLED), and more particularly to a bottom emission microLED display and a repair method thereof.
2. Description of Related ArtA micro light-emitting diode (microLED, mLED or μLED) display panel is one of flat display panels, and is composed of microscopic microLEDs each having a size of 1-10 micrometers. Compared to conventional liquid crystal display panels, the microLED display panels offer better contrast, response time and energy efficiency. Although both organic light-emitting diodes (OLEDs) and microLEDs possess good energy efficiency, the microLEDs, based on group III/V (e.g., GaN) LED technology, offer higher brightness, higher luminous efficacy and longer lifespan than the OLEDs.
During manufacturing a microLED display panel, individual microLEDs should be picked up and transferred to a display panel by electrostatic force, magnetic force or vacuum suction force. In practice, while performing picking, transferring and bonding, some individual microLEDs may be picked up and released abnormally, or the microLEDs are defective. After the microLEDs are bonded with a substrate of the display panel, it is difficult to repair those microLEDs that are defective or cannot be operated normally. A destructive scheme is usually adopted to perform the repairing, which is complicated and time-consuming.
A need has thus arisen to propose a simple and fast scheme to repair a microLED display panel.
SUMMARY OF THE INVENTIONIn view of the foregoing, it is an object of the embodiment of the present invention to provide a bottom emission microLED display and a repair method thereof. The repair method of the microLED display can repair the microLED display fast and conveniently without using destructive scheme.
According to one embodiment, a bottom emission micro light-emitting diode (microLED) display includes a transparent substrate, a microLED, a light guiding layer and a reflecting layer. The microLED is disposed above the transparent substrate. The light guiding layer surrounds the microLED to controllably guide light generated by the microLED towards the transparent substrate. The reflecting layer is formed over the light guiding layer to reflect the light generated by the microLED downwards and to confine the light generated by the microLED to prevent the light from leaking upwards or sidewards.
According to a repair method of a bottom emission micro light-emitting diode (microLED) display of one embodiment, a transparent substrate is provided with an original area and a repair area. A first conductive layer is formed to result in a selection electrode and an extended electrode extended from the selection electrode towards the repair area. A vertical-type original microLED is disposed above the selection electrode, which bonds and electrically connects with a first electrode of the microLED. A first light guiding layer is entirely formed above the transparent substrate, the selection electrode, the extended electrode and the original microLED. The first light guiding layer is etched to expose a second electrode of the original microLED and the transparent substrate in the repair area. A second conductive layer is formed to result in a common electrode above the first light guiding layer in the original area, thereby electrically connecting with the second electrode of the original microLED, and to result in the second conductive layer above the exposed transparent substrate in the repair area, wherein the extended electrode and the second conductive layer in the repair area partially overlap. When the original microLED passes a functional test, the following steps are performed: forming entirely a second light guiding layer above the common electrode and the first light guiding layer; etching the second light guiding layer to expose the common electrode and forming a top electrode above the second light guiding layer to electrically connect with the common electrode. When the original microLED fails the function test, the following steps are performed: disposing a vertical-type repair microLED on the second conductive layer above the exposed transparent substrate in the repair area, such that a first electrode of the repair microLED bonds and electrically connects with the second conductive layer above the exposed transparent substrate; welding to electrically connect the partially overlapped second conductive layer and the extended electrode; forming entirely the second light guiding layer above the repair microLED, the common electrode in the original area and the first light guiding layer; and etching the second light guiding layer to expose the common electrode and a second electrode of the repair microLED, and forming the top electrode above the second light guiding layer to electrically connect the common electrode and the second electrode of the repair microLED.
According to a repair method of a bottom emission micro light-emitting diode (microLED) display of another embodiment, a transparent substrate is provided. A selection electrode is formed above the transparent substrate. A first insulating layer is formed above the transparent substrate and the selection electrode. A through hole is formed in the first insulating layer. A conductive layer and a common electrode are formed above the first insulating layer, the conductive layer filling the through hole and thus electrically connecting with the selection electrode. A flip-chip type original microLED is disposed above the conductive layer and the common electrode such that a first electrode of the original microLED bonds and electrically connects with the conductive layer, and a second electrode of the original microLED bonds and electrically connects with the common electrode. When the original microLED fails a functional test, a repair microLED is disposed above the conductive layer and the common electrode, such that a first electrode of the repair microLED bonds and electrically connects with the conductive layer and a second electrode of the repair microLED bonds and electrically connects with the common electrode. The functional test and disposing a repair microLED are repeated until passing the functional test. A light guiding layer is formed above the first insulating layer, the conductive layer, the common electrode, the original microLED and the repair microLED. A reflecting layer is formed above the light guiding layer.
The bottom emission microLED display 100 (“microLED display” hereinafter) may include a transparent substrate 12, which may, for example, be made of glass or other non-conductive transparent material. An insulating layer 10 may be formed entirely above the transparent substrate 12. The insulating layer 10 may be an inter-layer dielectric (ILD) layer, which may include electrically insulating material such as silicon oxide or silicon nitride. A portion of the insulating layer 10 may be etched to expose the transparent substrate 12. A selection electrode 13, which may include electrically conductive material such as metal, may be formed on the exposed transparent substrate 12. As shown in
The bottom emission microLED display 200 (“microLED display” hereinafter) may include a transparent substrate 12 with a selection electrode 13 formed thereon. The microLED display 200 may include an insulating layer 16 covering the transparent substrate 12 and the selection electrode 13. In the embodiment, the insulating layer 16 may be an inter-layer dielectric (ILD) layer, which may include electrically insulating material such as silicon oxide or silicon nitride. A common electrode 15 and a conductive layer 17 (including conductive material such as metal) may be formed above the insulating layer 16. As shown in
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Compared to the vertical-type microLED display 300 of the third embodiment (
Although specific embodiments have been illustrated and described, it will be appreciated by those skilled in the art that various modifications may be made without departing from the scope of the present invention, which is intended to be limited solely by the appended claims.
Claims
1. A bottom emission micro light-emitting diode (microLED) display, comprising:
- a transparent substrate;
- a microLED disposed above the transparent substrate;
- a light guiding layer surrounding the microLED to controllably guide light generated by the microLED towards the transparent substrate; and
- a reflecting layer formed over the light guiding layer to reflect the light generated by the microLED downwards and to confine the light generated by the microLED to prevent the light from leaking upwards or sidewards.
2. The display of claim 1, further comprising a selection electrode disposed above the transparent substrate, and electrically connected with a first electrode of the microLED.
3. The display of claim 2, wherein the microLED is a vertical-type microLED.
4. The display of claim 3, wherein the reflecting layer acts as a common electrode that electrically connects with a second electrode of the microLED.
5. The display of claim 3, further comprising an insulating layer disposed above the transparent substrate, a portion of the insulating layer being etched to expose the transparent substrate, and the selection electrode being disposed on the exposed transparent substrate.
6. The display of claim 2, wherein the microLED is a flip-chip type microLED.
7. The display of claim 6, further comprising:
- an insulating layer disposed above the transparent substrate and the selection electrode; and
- a conductive layer disposed above the insulating layer, the conductive layer electrically connecting with the selection electrode;
- wherein a first electrode of the microLED bonds and electrically connects with the conductive layer.
8. The display of claim 6, further comprising a common electrode disposed between the microLED and the transparent substrate, and electrically connected with a second electrode of the microLED.
9. The display of claim 1, wherein the transparent substrate comprises glass.
10. The display of claim 1, wherein the light guiding layer comprises transparent material with diffractive index higher than 1.4.
11. The display of claim 1, wherein the light guiding layer comprises polymer.
12. The display of claim 1, wherein the reflecting layer comprises electrically conductive material.
13. The display of claim 12, wherein the reflecting layer comprises metal.
14. A repair method of a bottom emission micro light-emitting diode (microLED) display, comprising:
- providing a transparent substrate with an original area and a repair area;
- forming a first conductive layer to result in a selection electrode and an extended electrode extended from the selection electrode towards the repair area;
- disposing a vertical-type original microLED above the selection electrode, which bonds and electrically connects with a first electrode of the microLED;
- forming entirely a first light guiding layer above the transparent substrate, the selection electrode, the extended electrode and the original microLED;
- etching the first light guiding layer to expose a second electrode of the original microLED and the transparent substrate in the repair area;
- forming a second conductive layer to result in a common electrode above the first light guiding layer in the original area, thereby electrically connecting with the second electrode of the original microLED, and to result in the second conductive layer above the exposed transparent substrate in the repair area, wherein the extended electrode and the second conductive layer in the repair area partially overlap;
- when the original microLED passes a functional test, performing the following steps: forming entirely a second light guiding layer above the common electrode and the first light guiding layer; etching the second light guiding layer to expose the common electrode and forming a top electrode above the second light guiding layer to electrically connect with the common electrode;
- when the original microLED fails the function test, performing the following steps: disposing a vertical-type repair microLED on the second conductive layer above the exposed transparent substrate in the repair area, such that a first electrode of the repair microLED bonds and electrically connects with the second conductive layer above the exposed transparent substrate; welding to electrically connect the partially overlapped second conductive layer and the extended electrode; forming entirely the second light guiding layer above the repair microLED, the common electrode in the original area and the first light guiding layer; and etching the second light guiding layer to expose the common electrode and a second electrode of the repair microLED, and forming the top electrode above the second light guiding layer to electrically connect the common electrode and the second electrode of the repair microLED.
15. The method of claim 14, wherein the partially overlapped second conductive layer and the extended electrode are welded by laser welding technique.
16. The method of claim 14, wherein the exposed transparent substrate in the repair area is adjacent to the extended electrode.
17. The method of claim 14, before forming the selection electrode, further comprising a step of forming entirely an insulating layer above the transparent substrate, a portion of the insulting layer being etched to expose the transparent substrate, and the selection electrode being disposed above the exposed transparent substrate.
18. A bottom emission micro light-emitting diode (microLED) display, comprising:
- a transparent substrate with an original area and a repair area;
- a selection electrode formed above the transparent substrate in the original area, an extended electrode being extended from the selection electrode towards the repair area;
- a vertical-type original microLED disposed above the selection electrode, which bonds and electrically connects with a first electrode of the original microLED;
- a first light guiding layer formed above the transparent substrate, the selection electrode, the extended electrode and the original microLED, the first light guiding layer not covering an exposed transparent substrate in the repair area;
- a common electrode formed above the first light guiding layer in the original area, and electrically connected with a second electrode of the original microLED;
- a second conductive layer formed above the exposed transparent substrate in the repair area, wherein the extended electrode and the second conductive layer in the repair area partially overlap and are welded and electrically connected;
- a vertical-type repair microLED disposed on the second conductive layer above the exposed transparent substrate in the repair area, such that the first electrode of the repair microLED bonds and electrically connects with the second conductive layer above the exposed transparent substrate;
- a second light guiding layer formed above the repair microLED in the repair area, the common electrode and the first light guiding layer in the original area; and
- a top electrode formed above the second light guiding layer to electrically connect the common electrode and the second electrode of the repair microLED.
19. The display of claim 18, wherein the exposed transparent substrate in the repair area is adjacent to the extended electrode.
20. The display of claim 18, wherein the transparent substrate comprises glass.
21. The display of claim 18, wherein the first light guiding layer and the second light guiding layer comprise transparent material with diffractive index higher than 1.4.
22. The display of claim 18, wherein the first light guiding layer and the second light guiding layer comprise polymer.
23. The display of claim 18, wherein the common electrode and the top electrode comprise metal.
24. The display of claim 18, further comprising an insulating layer entirely formed above the transparent substrate, a portion of the insulating layer being etched to expose the transparent substrate and the selection electrode being disposed above the exposed transparent substrate.
25. A repair method of a bottom emission micro light-emitting diode (microLED) display, comprising:
- providing a transparent substrate;
- forming a selection electrode above the transparent substrate;
- forming a first insulating layer above the transparent substrate and the selection electrode;
- forming a through hole in the first insulating layer;
- forming a conductive layer and a common electrode above the first insulating layer, the conductive layer filling the through hole and thus electrically connecting with the selection electrode;
- disposing a flip-chip type original microLED above the conductive layer and the common electrode such that a first electrode of the original microLED bonds and electrically connects with the conductive layer, and a second electrode of the original microLED bonds and electrically connects with the common electrode;
- when the original microLED fails a functional test, disposing a repair microLED above the conductive layer and the common electrode, such that a first electrode of the repair microLED bonds and electrically connects with the conductive layer and a second electrode of the repair microLED bonds and electrically connects with the common electrode;
- repeating the functional test and disposing a repair microLED until passing the functional test;
- forming a light guiding layer above the first insulating layer, the conductive layer, the common electrode, the original microLED and the repair microLED; and
- forming a reflecting layer above the light guiding layer.
26. The method of claim 25, wherein the repair microLED and the original microLED are at a same level.
27. The method of claim 25, wherein the original microLED is far away from the selection electrode and the repair microLED is near the selection electrode.
28. The method of claim 27, when the original microLED makes shorting between the conductive layer and the common electrode, the conductive layer or the common electrode located between the original microLED and the repair microLED is cut off.
29. The method of claim 25, further comprising:
- forming a second insulating layer between the transparent substrate and the first insulating layer; and
- forming a bottom conductive layer in the second insulating layer and on a top surface of the transparent substrate.
30. A bottom emission micro light-emitting diode (microLED) display, comprising:
- a transparent substrate;
- a selection electrode formed above the transparent substrate;
- a first insulating layer formed above the transparent substrate and the selection electrode, a through hole being formed in the first insulating layer;
- a conductive layer and a common electrode formed above the first insulating layer, the conductive layer filling the through hole to electrically connect with the selection electrode;
- a flip-chip type original microLED disposed above the conductive layer and the common electrode layer, such that a first electrode of the original microLED bonds and electrically connects with the conductive layer and a second electrode of the original microLED bonds and electrically connects with the common electrode;
- at least one repair microLED disposed above the conductive layer and the common electrode, such that a first electrode of the repair microLED bonds and electrically connects with the conductive layer and a second electrode of the repair microLED bonds and electrically connects with the common electrode;
- a light guiding layer disposed above the first insulating layer, the conductive layer, the common electrode, the original microLED and the repair microLED; and
- a reflecting layer disposed above the light guiding layer.
31. The display of claim 30, wherein the repair microLED and the original microLED are at a same level.
32. The display of claim 30, wherein the original microLED is far away from the selection electrode and the repair microLED is near the selection electrode.
33. The display of claim 30, wherein the transparent substrate comprises glass.
34. The display of claim 30, wherein the light guiding layer comprises transparent material with diffractive index higher than 1.4.
35. The display of claim 30, wherein the light guiding layer comprises polymer.
36. The display of claim 30, wherein the reflecting layer comprises conductive material.
37. The display of claim 36, wherein the reflecting layer comprises metal.
38. The display of claim 30, further comprising:
- a second insulating layer formed between the transparent substrate and the first insulating layer; and
- a bottom conductive layer formed in the second insulating layer and on a top surface of the transparent substrate.
Type: Application
Filed: Apr 26, 2018
Publication Date: Nov 8, 2018
Inventors: Biing-Seng Wu (Tainan City), Chao-Wen Wu (Tainan City)
Application Number: 15/963,477