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EP-4739044-A1 - VERTICALLY STACKED RED-GREEN-BLUE FULL-COLOR CHIP-ON-CARRIER FOR MICROLED DISPLAY PANELS AND METHOD OF MANUFACTURING THE SAME

EP4739044A1EP 4739044 A1EP4739044 A1EP 4739044A1EP-4739044-A1

Abstract

The present disclosure relates to a vertically stacked red-green-blue full-color chip-on-carrier for a microLED display panel, and the vertically stacked red-green-blue full-color chip-on-carrier for a microLED display panel includes a temporary wafer, and a plurality of light-emitting diode (LED) stacks each including light-emitting portions stacked in a vertical direction through a bonding layer and aligned on the temporary wafer, wherein each of the plurality of LED stacks has a short passage formed in a partial region, such that current flows to the light-emitting portion where the short passage is not formed to emit only a specific color, and the short passage includes a first short passage formed to correspond to a width of the light-emitting portion and a second short passage formed to pass through the light-emitting portion. According to the present disclosure, since a chip-on-carrier is formed with a plurality of LED stacks in which a plurality of light-emitting portions are vertically stacked on a temporary wafer, and each of the plurality of LED stacks has been already formed with a short passage, a company which receives the chip-on-carrier may easily manufacture a microLED display panel with only a bonding process to a silicon (Si) CMOS or glass TFT backplane wafer without performing a separate epitaxy growth or stacking process. Accordingly, there are effects that a manufacturing process is simplified, the burden on manufacturing equipment and infrastructure is reduced, a process time is shortened, and manufacturing yield is enhanced.

Inventors

  • SONG, JUNEO
  • MOON, JI HYUNG
  • KIM, TAE KYOUNG
  • YUN, HYEONG SEON

Assignees

  • Wavelord Co., Ltd

Dates

Publication Date
20260506
Application Date
20251022

Claims (10)

  1. A vertically stacked red-green-blue full-color chip-on-carrier for a microLED display panel, comprising: a temporary wafer; and a plurality of light-emitting diode (LED) stacks each including light-emitting portions stacked in a vertical direction through a bonding layer and aligned on the temporary wafer, wherein each of the plurality of LED stacks has a short passage formed in a partial region, such that current flows to the light-emitting portion where the short passage is not formed to emit only a specific color, and the short passage includes a first short passage formed to correspond to a width of the light-emitting portion and a second short passage formed to pass through the light-emitting portion.
  2. The vertically stacked red-green-blue full-color chip-on-carrier of claim 1, wherein the plurality of LED stacks include a first LED stack including a first light-emitting portion that emits a first color, a second LED stack including a second light-emitting portion that emits a second color, and a third LED stack including a third light-emitting portion that emits a third color.
  3. The vertically stacked red-green-blue full-color chip-on-carrier of claim 2, wherein the first LED stack includes the first short passage formed in a portion of the third light-emitting portion, and the second short passage formed to pass through the second light-emitting portion, the second LED stack includes the first short passage formed in the portion of the third light-emitting portion, and the first short passage formed in a portion of the first light-emitting portion, and the third LED stack includes the second short passage formed to pass through the second light-emitting portion, and the first short passage formed in the portion of the first light-emitting portion.
  4. The vertically stacked red-green-blue full-color chip-on-carrier of any one of claims 1 to 3, wherein a common electrode is formed on upper portions or lower portions of the plurality of LED stacks.
  5. The vertically stacked red-green-blue full-color chip-on-carrier of any one of claims 1 to 4, wherein a sacrificial separation layer is formed on the temporary wafer.
  6. A method of manufacturing a vertically stacked red-green-blue full-color chip-on-carrier for a microLED display panel, comprising: a preparation step of preparing a plurality of front wafers including a support wafer and light-emitting portions; a stacking step of forming a stack in which the plurality of light-emitting portions are vertically stacked on the support wafer by repeatedly bonding another front wafer onto one front wafer through a bonding layer and then removing the support wafer of the other front wafer; a first processing step of forming a short passage on one surface of the stack; a second processing step of bonding a temporary wafer to one surface of the stack, removing the support wafer, and then forming the short passage on the other surface of the stack; and an etching step of etching the stack and separating the stack into preset units to allow the plurality of LED stacks to be aligned on the temporary wafer, wherein each of the plurality of LED stacks is formed with a short passage in a partial region, such that current flows to the light-emitting portion where the short passage is not formed to emit only a specific color, and the short passage includes a first short passage formed to correspond to a width of the light-emitting portion and a second short passage formed to pass through the light-emitting portion.
  7. The method of claim 6, wherein the plurality of LED stacks include a first LED stack including a first light-emitting portion that emits a first color, a second LED stack including a second light-emitting portion that emits a second color, and a third LED stack including a third light-emitting portion that emits a third color.
  8. The method of claim 7, wherein the first LED stack includes the first short passage formed in a portion of the third light-emitting portion, and the second short passage formed to pass through the second light-emitting portion, the second LED stack includes the first short passage formed in the portion of the third light-emitting portion, and the first short passage formed in a portion of the first light-emitting portion, and the third LED stack includes the second short passage formed to pass through the second light-emitting portion, and the first short passage formed in the portion of the first light-emitting portion.
  9. The method of any one of claims 6 to 8, wherein a common electrode is formed on upper portions or lower portions of the plurality of LED stacks.
  10. The method of any one of claims 6 to 9, wherein a sacrificial separation layer is formed on the temporary wafer.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to and the benefit of Korean Patent Application No. 10-2024-0151592, filed on 30 October 2024; No. 10-2024-0177192, filed on 3 December 2024, No. 10-2024-0177193, filed on 3 December 2024 and No. 10-2025-0124032, filed on 2 September 2025 the disclosure of which is incorporated herein by reference in its entirety. BACKGROUND 1. Field of the Invention The present disclosure relates to a vertically stacked red-green-blue full-color chip-on-carrier for a microLED display panel, and a method of manufacturing the same, and more specifically, to a vertically stacked red-green-blue full-color chip-on-carrier for a microLED display panel in which a color filter is not required by using an engineering monolithic epitaxy wafer method and allowing each of the LED stacks to emit only a specific color, and a method of manufacturing the same. 2. Discussion of Related Art The types of implementation of the metaverse, which has recently been attracting attention, are classified into four types such as virtual reality (VR), augmented reality (AR), mixed reality (MR), and extended reality (XR). It is expected that the metaverse ecosystem will develop in the future, focusing on XR, which is a reality that combines VR, AR, and MR among the four types. In addition, in order to implement this effectively, devices (for example, smart glasses, head-mounted displays, and the like) that include microdisplays with a diagonal length of less than one inch as a core component, along with software for next-generation computing platforms that can deliver innovative user experiences, are required. Particularly, the development of high-performance microdisplay panel technology is absolutely necessary to provide XR users with the greatest immersion, visibility, and convenience and minimize dizziness. As shown in FIG. 1, a conventional microdisplay panel 10 corresponds to a technology that combines a Si CMOS semiconductor wafer process and a high-resolution, high-brightness, ultra-small display process, and the conventional microdisplay panel 10 may have a structure in which a Si CMOS wafer 11 that has a (100) crystal plane of 4" or more and is provided with a plurality of CMOS electrode pads 12, a plurality of microLED electrode pads 14, and a transparent wafer 13 of 4" or more that is provided with a plurality of microLED chips 15 are bonded through a conductive bond 16. Meanwhile, the types of microdisplay panels expected to be applied to XR devices include liquid crystal (LC)-based LC on Si (LCoS), organic light-emitting diode (OLED)-based OLED on Si (OLEDoS), and LED on Si (LEDoS) based on ultra-small microLEDs with pixel sizes of less than 5 µm. In addition, in the case of VR where displays with a low pixel density are applied, the microdisplay panels are being developed and mass-produced mainly based on LCoS and OLEDoS. However, with the advancement of metaverse implementation technology, the need for lightweight AR, MR, and XR devices to which microdisplay panels with a high pixel density are applied is gradually increasing. In addition, although the development of LEDoS (a microLED pixel light source composed of red-green-blue subpixels less than 5 µm is adopted) technology, which is considered an ideal solution in theory based on its superior inorganic properties, is urgently needed to satisfy these needs, a microdisplay panel platform for this has not yet been established. LEDoSs based on ultra-small microLEDs with pixel sizes of less than 5 µm have the advantages of an excellent power-to-performance ratio (P/P) and a short response speed when applied to XR devices, and since the LEDoSs are composed of inorganic materials, there are the advantages that the LEDoSs have a long lifespan, and have efficient power use to reduce heat generation and enable long-term battery life. Particularly, since XR devices have a very short distance between the display and the eyes, even a slight delay in image conversion can easily cause discomfort such as dizziness. Thus, LEDoS, which has a nanosecond response speed, is considered to be the most suitable for XR devices compared to LCoS and OLEDoS, which have a microsecond response speed. Furthermore, it is evaluated that the biggest reason why LEDoS is attracting attention in AR, MR, and XR devices, unlike VR, is due to its brightness and luminous efficiency. Since smart glasses can be worn regardless of location, high brightness is essential for normal operation even in outdoor environments such as sunlight. In theory, microLEDs support brightness of tens to millions of nits, and since OLEDs are made of organic materials, whereas microLEDs are made of inorganic materials, the microLEDs also have the advantage of high luminous efficiency. However, despite the above-described advantages, the biggest reason why LEDoSs based on ultra-small microLEDs with pixel sizes of less than 5 µm have not established as a major component of XR