US-20260130028-A1 - MICRO LIGHT EMITTING DISPLAY DEVICE AND METHOD OF MANUFACTURING THE SAME

Abstract

A micro-light emitting display device includes a backplane substrate including at least one driving device, a bonding layer on the backplane substrate, a first bonding pillar extending in a first direction that is perpendicular to an upper surface of the backplane substrate, and a first light emitting device and a second light emitting device spaced apart from each other in a second direction intersecting the first direction, where the first light emitting device is on the bonding layer and the second light emitting device is on the first bonding pillar such that the second light emitting device is positioned at a height in the first direction that is different from a height at which the first light emitting device is positioned in the first direction.

Inventors

• Junhee Choi
• Kiho Kong
• Nakhyun Kim
• Sunil Kim

Assignees

• SAMSUNG ELECTRONICS CO.,LTD.

Dates

Publication Date

20260507

Application Date

20251031

Priority Date

20241101

Claims (20)

1. 1 . A micro light emitting display device comprising: a backplane substrate comprising at least one driving device; a bonding layer on the backplane substrate; a first bonding pillar extending in a first direction that is perpendicular to an upper surface of the backplane substrate; and a first light emitting device and a second light emitting device spaced apart from each other in a second direction intersecting the first direction; wherein the first light emitting device is on the bonding layer, and wherein the second light emitting device is on the first bonding pillar such that the second light emitting device is positioned at a height in the first direction that is different from a height at which the first light emitting device is positioned in the first direction.
2. 2 . The micro light emitting display device of claim 1 , wherein the first bonding pillar is between the bonding layer and the second light emitting device and protrudes from the bonding layer toward the second light emitting device.
3. 3 . The micro light emitting display device of claim 1 , wherein the first bonding pillar comprises a polymer-based material.
4. 4 . The micro light emitting display device of claim 1 , wherein the first bonding pillar comprises a material that is the same as a material of the bonding layer.
5. 5 . The micro light emitting display device of claim 1 , wherein the first light emitting device comprises a first electrode, a first semiconductor layer, a first active layer configured to emit light of a first wavelength, a second semiconductor layer, and a second electrode, which are stacked in order in the first direction, wherein the second light emitting device comprises a third electrode, a third semiconductor layer, a second active layer configured to emit light having a second wavelength different from the first wavelength, a fourth semiconductor layer, and a fourth electrode, which are stacked in order in the first direction, wherein, in the second direction, the first electrode has a width that is greater than a width of the first semiconductor layer, wherein the first electrode comprises a first open surface extending from a side of the first light emitting device and connected to at least one driving device of the at least one driving device, wherein, in the second direction, the third electrode has a width that is greater than a width of the third semiconductor layer, and wherein the third electrode comprises a second open surface extending from a side of the second light emitting device and connected to at least one driving device of the at least one driving device.
6. 6 . The micro light emitting display device of claim 5 , wherein, in the second direction, the first bonding pillar has a width that is greater than a width of the second active layer of the second light emitting device.
7. 7 . The micro light emitting display device of claim 5 , wherein, in the second direction, the first bonding pillar has a width that is substantially the same as the width of the third electrode.
8. 8 . The micro light emitting display device of claim 5 , further comprising a first conductive layer configured to connect the at least one driving device to at least one of the first open surface and the second open surface.
9. 9 . The micro light emitting display device of claim 8 , further comprising a planarization layer covering the first conductive layer, wherein a surface of the first light emitting device and a surface of the second light emitting device are exposed through the planarization layer.
10. 10 . The micro light emitting display device of claim 9 , further comprising a second conductive layer contacting the surface of the first light emitting device and the surface of the second light emitting device which are exposed through the planarization layer.
11. 11 . The micro light emitting display device of claim 10 , further comprising: a first lens above the first light emitting device and having a convex upper portion; and a second lens above the second light emitting device and having a convex upper portion.
12. 12 . The micro light emitting display device of claim 9 , wherein the planarization layer comprises a first hole exposing the surface of the first light emitting device, and wherein the micro light emitting display device further comprises a reflective layer on a side surface of the first hole.
13. 13 . The micro light emitting display device of claim 1 , wherein a surface of the first light emitting device and a surface of the second light emitting device each comprise an uneven structure.
14. 14 . The micro light emitting display device of claim 1 , further comprising: a second bonding pillar extending in the first direction to a height that is different from a height of the first bonding pillar; and a third light emitting device on the second bonding pillar and spaced apart from the second light emitting device in the second direction such that the third light emitting device is positioned at a height in the first direction that is different from the height of the first light emitting device in the first direction and the height of the second light emitting device in the first direction.
15. 15 . A method of manufacturing a micro light emitting display device, the method comprising: providing a first bonding layer on a backplane substrate; forming a first light emitting device on the first bonding layer; providing a second bonding layer that covers the first light emitting device and the first bonding layer; forming a second light emitting device on the second bonding layer; and etching the second bonding layer such that a first bonding pillar is formed below the second light emitting device in a first direction that is perpendicular to an upper surface of the backplane substrate.
16. 16 . The method of claim 15 , wherein the forming of the first light emitting device comprises: forming a first epitaxial structure by providing a second epitaxial semiconductor layer, a first epitaxial active layer, a first epitaxial semiconductor layer, and a first epitaxial electrode in order on a first epitaxial substrate; inverting the first epitaxial structure and providing the inverted first epitaxial structure on the first bonding layer; removing the first epitaxial substrate of the first epitaxial structure; forming a second epitaxial electrode on the first epitaxial structure; and etching the first epitaxial structure such that a width of the first light emitting device is on the upper surface of the first bonding layer, and wherein the forming of the second light emitting device comprises: forming a second epitaxial structure by providing a third epitaxial electrode on the second bonding layer, a third epitaxial semiconductor layer on the third epitaxial electrode, a second epitaxial active layer on the third epitaxial semiconductor layer, and a fourth epitaxial semiconductor layer on the second epitaxial active layer; forming a fourth epitaxial electrode on the second epitaxial structure; and etching the second epitaxial structure such that a width of the second light emitting device is less than a width of the second bonding layer.
17. 17 . The method of claim 16 , wherein the backplane substrate comprises at least one driving device; wherein the first light emitting device comprises a first electrode, a first semiconductor layer, a first active layer configured to emit light of a first wavelength, a second semiconductor layer, and a second electrode, which are stacked in order on the first bonding layer, wherein the second light emitting device comprises a third electrode, a third semiconductor layer, a second active layer configured to emit light having a second wavelength different from the first wavelength, a fourth semiconductor layer, and a fourth electrode, which are stacked in order on the second bonding layer; wherein the first electrode has a width that is greater than a width of the first semiconductor layer and comprises a first open surface extending from a side of the first light emitting device; wherein the third electrode has a width that is greater than a width of the third semiconductor layer and comprises a second open surface extending from a side of the second light emitting device, and wherein the method further comprises forming a first conductive layer respectively connecting driving devices of the at least one driving device to the first electrode and the second electrode.
18. 18 . The method of claim 17 , further comprising: forming a planarization layer covering the first conductive layer; forming a first hole in the planarization layer exposing the second electrode of the first light emitting device; forming a second hole in the planarization layer exposing the fourth electrode of the second light emitting device; and forming a second conductive layer that contacts the second electrode exposed through the first hole and the fourth electrode exposed through the second hole.
19. 19 . The method of claim 18 , further comprising: forming a first lens filling the first hole and having a shape with a convex upper portion; and forming a second lens filling the second hole and having a shape with a convex upper portion.
20. 20 . The method of claim 19 , further comprising, prior to forming the first lens, forming a reflective layer on a side surface of the first hole.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is based on and claims priority to Korean Patent Application No. 10-2024-0153787, filed on November 01, 2024, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety. BACKGROUND 1. Field The disclosure relates to a micro light emitting display device for displaying a color image and a method of manufacturing the same. 2. Description of Related Art Liquid crystal displays (LCD) and organic light emitting diode (LED) (OLED) displays are widely used as display devices. In addition, a technology for manufacturing high-resolution display devices using micro LEDs has recently been in the spotlight. Micro LEDs have the advantages of low-power consumption and environmental friendliness. Due to these advantages, the industrial demands for micro LEDS are increasing. LED displays that directly use micro LEDs as pixels have been developed and commercialized. An LED display pixel may be designed in various ways, and recently, various technologies for vertically stacking micro LEDs emitting red light (R), which are abbreviated as R-LEDs), a micro LEDs emitting green light (G), which are abbreviated as G-LEDs), and micro LEDs emitting blue light (B), which are abbreviated as B-LEDs), have been introduced. However, vertical stacking of micro LEDs has not yet yielded satisfactory results in terms of efficiency or bonding. Information disclosed in this Background section has already been known to or derived by the inventors before or during the process of achieving the embodiments of the present application, or is technical information acquired in the process of achieving the embodiments. Therefore, it may contain information that does not form the prior art that is already known to the public. SUMMARY Provided is a micro light emitting display device and a method of manufacturing a micro light emitting display device. 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 presented embodiments of the disclosure. According to an aspect of the disclosure, a micro-light emitting display device may include a backplane substrate including at least one driving device, a bonding layer on the backplane substrate, a first bonding pillar extending in a first direction that is perpendicular to an upper surface of the backplane substrate, and a first light emitting device and a second light emitting device spaced apart from each other in a second direction intersecting the first direction, where the first light emitting device is on the bonding layer and the second light emitting device is on the first bonding pillar such that the second light emitting device is positioned at a height in the first direction that is different from a height at which the first light emitting device is positioned in the first direction. The first bonding pillar may be between the bonding layer and the second light emitting device and may protrude from the bonding layer toward the second light emitting device. The first bonding pillar may include a polymer-based material. The first bonding pillar may include a material that is the same as a material of the bonding layer. The first light emitting device may include a first electrode, a first semiconductor layer, a first active layer configured to emit light of a first wavelength, a second semiconductor layer, and a second electrode, which are stacked in order in the first direction, the second light emitting device may include a third electrode, a third semiconductor layer, a second active layer configured to emit light having a second wavelength different from the first wavelength, a fourth semiconductor layer, and a fourth electrode, which are stacked in order in the first direction, in the second direction, the first electrode may have a width that is greater than a width of the first semiconductor layer, the first electrode may include a first open surface extending from a side of the first light emitting device and connected to at least one driving device of the at least one driving device, in the second direction, the third electrode may have a width that is greater than a width of the third semiconductor layer, and the third electrode may include a second open surface extending from a side of the second light emitting device and may be connected to at least one driving device of the at least one driving device. In the second direction, the first bonding pillar may have a width that is greater than a width of the second active layer of the second light emitting device. In the second direction, the first bonding pillar may have a width that is substantially the same as the width of the third electrode. The display device may include a first conductive layer configured to connect the at least one driving device to at least one of the first open surface and the second open sur