KR-102961661-B1 - MICRODISPLAY PANEL AND MANUFACTURING METHOD THEREOF

KR102961661B1KR 102961661 B1KR102961661 B1KR 102961661B1KR-102961661-B1

Abstract

The present invention relates to a microdisplay panel comprising: a back wafer having a plurality of CMOS electrode pads aligned on its upper surface; and a plurality of LED stacks disposed on the back wafer, wherein each of the LED stacks comprises a bonding layer, a first functional layer formed on the bonding layer, a first electrode formed on the first functional layer, a light-emitting part formed on the first electrode, and a second electrode formed on the light-emitting part, wherein the unit layer further comprises a second functional layer formed below the bonding layer, wherein the first functional layer is electrically connected to the second functional layer through a connecting electrode, and the second functional layer is electrically connected to the CMOS electrode pad. According to the present invention, unlike conventional monolithic integration methods or hybridization methods that have alignment issues, an engineering monolithic epitaxy wafer is first fabricated, and then a stack on the engineering monolithic epitaxy wafer is etched to separate it into preset units, thereby allowing a plurality of LED stacks to be aligned on a backplane wafer. This enables the use of not only small-diameter wafers of 6 inches or less, but also large-diameter wafers of 8 inches or more, thereby having the effect of significantly increasing the product yield.

Inventors

송준오
문지형

Assignees

웨이브로드 주식회사

Dates

Publication Date: 20260513
Application Date: 20250724
Priority Date: 20250324

Claims (12)

A back wafer having a plurality of CMOS electrode pads aligned on its upper surface; and It includes a plurality of LED stacks disposed on the back wafer, and Each of the above LED stacks is, It includes a bonding layer, a first functional layer formed on the bonding layer, a first electrode formed on the first functional layer, a light-emitting part formed on the first electrode, and a second electrode formed on the light-emitting part. The above LED laminate is, It further includes a second functional layer formed on the lower part of the bonding layer, and The above-mentioned first functional layer is, It is electrically connected to the second functional layer through a connecting electrode, and The above second functional layer is, A microdisplay panel electrically connected to the above CMOS electrode pad.
In claim 1, The above bonding layer is, A microdisplay panel formed of an electrically insulating material.
In claim 1, The first functional layer and the second functional layer are A microdisplay panel formed of an electrically conductive material.
A back wafer having a plurality of CMOS electrode pads aligned on its upper surface; and A plurality of unit layers stacked on the above back wafer, each comprising a plurality of LED stacks, and Each of the above LED stacks is, It includes a bonding layer, a first functional layer formed on the bonding layer, a first electrode formed on the first functional layer, a light-emitting part formed on the first electrode, and a second electrode formed on the light-emitting part. The LED laminate included in the unit layer of the lowest layer, It further includes a second functional layer formed on the lower part of the bonding layer, and The above-mentioned first functional layer is, It is electrically connected to the second electrode of the lower layer through a connecting electrode, or electrically connected to the second functional layer, and The above second functional layer is, Electrically connected to the above CMOS electrode pad, and The above unit layer is, A microdisplay panel that emits only a specific color by forming a short path in at least one of the plurality of LED laminates, thereby allowing current to flow only to the LED laminates where the short path is not formed.
In claim 4, The above bonding layer is, A microdisplay panel formed of an electrically insulating material.
In claim 4, The first functional layer and the second functional layer are A microdisplay panel formed of an electrically conductive material.
A back wafer having a plurality of CMOS electrode pads aligned on its upper surface; and A plurality of unit layers are stacked on the above-mentioned back wafer, each comprising an LED stack, and Each of the above LED stacks is, It includes a bonding layer, a first functional layer formed on the bonding layer, a first electrode formed on the first functional layer, a light-emitting part formed on the first electrode, and a second electrode formed on the light-emitting part. The LED laminate included in the unit layer of the lowest layer, It further includes a second functional layer formed on the lower part of the bonding layer, and The above-mentioned first functional layer is, It is electrically connected to the second electrode of the lower layer through a connecting electrode, or electrically connected to the second functional layer, and The above second functional layer is, Electrically connected to the above CMOS electrode pad, and The above unit layer is, For electrical connection between a plurality of the above unit layers, at least one vertical electrode is further included in place of the light-emitting part at some of the plurality of locations where the light-emitting part is to be placed, where the light-emitting part is not formed. On the upper part of the vertical electrode above, The above second electrode is formed, At the bottom of the vertical electrode included in the unit layer of the lowest layer, The above connecting electrode is formed, and the second functional layer is formed on the lower part of the above connecting electrode, and At the bottom of the vertical electrode included in the unit layer excluding the lowest layer, A microdisplay panel in which the above-mentioned connecting electrode is formed and electrically connected to the above-mentioned second electrode of the lower layer.
In claim 7, The above bonding layer is, A microdisplay panel formed of an electrically insulating material.
In claim 7, The first functional layer and the second functional layer are A microdisplay panel formed of an electrically conductive material.
A preparation step of preparing a front wafer having a light-emitting part and a first electrode formed on a support wafer, and a back wafer having a plurality of CMOS electrode pads aligned on its upper surface; A functional layer formation step of forming a first functional layer on the front wafer and forming a second functional layer on the back wafer that is electrically connected to the CMOS electrode pad; A bonding step of bonding the front wafer and the back wafer through a bonding layer, and then removing the support wafer to laminate the light-emitting part onto the back wafer; An etching step of etching the light-emitting part and the first electrode to separate them into preset units, etching the first functional layer and the bonding layer to separate them into preset units, and then exposing the second functional layer; A connecting electrode forming step for forming a connecting electrode that electrically connects the first functional layer and the second functional layer; and A method for manufacturing a microdisplay panel, comprising an upper electrode forming step of forming a second electrode on the light-emitting part.
A preparation step of preparing a front wafer having a light-emitting part and a first electrode formed on a support wafer, and a back wafer having a plurality of CMOS electrode pads aligned on its upper surface; A functional layer formation step of forming a first functional layer on the front wafer and forming a second functional layer on the back wafer that is electrically connected to the CMOS electrode pad; Using the front wafer, the method includes a stacking step of repeatedly stacking unit layers including LED stacks on the back wafer. The above stacking step is, A bonding step of bonding the front wafer and the back wafer through a bonding layer, and then removing the support wafer to laminate a light-emitting part on the back wafer; An etching step of etching the light-emitting part and the first electrode to separate them into preset units, etching the first functional layer and the bonding layer to separate them into preset units, and then exposing the second functional layer or the second electrode of the lower layer; A connecting electrode forming step for forming a connecting electrode that electrically connects the first functional layer and the second functional layer, or electrically connects the first functional layer and the second electrode of the lower layer; A through-hole forming step of forming a through-hole in at least one of the light-emitting parts separated into pre-set units; and A method for manufacturing a microdisplay panel, comprising an upper electrode forming step of filling the above-mentioned through hole to form a short passage and forming a second electrode on the light-emitting part and the above-mentioned short passage.
A preparation step of preparing a front wafer having a light-emitting part and a first electrode formed on a support wafer, and a back wafer having a plurality of CMOS electrode pads aligned on its upper surface; A functional layer formation step of forming a first functional layer on the front wafer and forming a second functional layer on the back wafer that is electrically connected to the CMOS electrode pad; Using the front wafer, the method includes a stacking step of repeatedly stacking unit layers including LED stacks on the back wafer. The above stacking step is, A bonding step of bonding the front wafer and the back wafer through a bonding layer, and then removing the support wafer to laminate a light-emitting part on the back wafer; An etching step of etching the light-emitting part and the first electrode to form them into a preset unit, etching the second functional layer and the bonding layer to form them into a preset unit, and then exposing the second functional layer or the second electrode of the lower layer; A connecting electrode forming step for forming a connecting electrode that electrically connects the first functional layer and the second functional layer, or electrically connects the first functional layer and the second electrode of the lower layer; A vertical electrode forming step for forming at least one vertical electrode disposed instead of a light-emitting part at a portion of a plurality of locations where the light-emitting part is to be disposed, wherein the light-emitting part is not formed, for electrical connection between a plurality of the above unit layers; and It includes an upper electrode forming step of forming a second electrode on the upper portion of the light-emitting part and the vertical electrode, respectively. At the bottom of the vertical electrode included in the unit layer of the lowest layer, The above connecting electrode is formed, and the second functional layer is formed on the lower part of the above connecting electrode, and At the bottom of the vertical electrode included in the unit layer excluding the lowest layer, A method for manufacturing a microdisplay panel in which the above-mentioned connecting electrode is formed and electrically connected to the above-mentioned second electrode of the lower layer.

Description

Microdisplay panel and manufacturing method thereof The present invention relates to a vertically stacked microdisplay panel and a method for manufacturing the same, and more specifically, to an LEDoS microdisplay panel and a method for manufacturing the same in which an alignment process between an LED stack and a CMOS electrode pad is not required through an engineering monolithic epitaxy wafer using a ceramic material when bonding a front wafer and a back wafer. The types of implementation for the recently trending Metaverse are classified into four forms: VR (virtual reality), AR (augmented reality), MR (mixed reality), and XR (extended reality). Among these, the future Metaverse ecosystem is expected to develop around XR, a reality that integrates VR, AR, and MR. To effectively implement this, devices (such as smart glasses and head-mounted displays) containing microdisplays with a diagonal length of less than one inch as core components are required, along with software for next-generation computing platforms capable of providing innovative user experiences. In particular, the development of high-performance microdisplay panel technology is absolutely necessary to provide XR users with the greatest sense of immersion, visibility, and convenience while minimizing dizziness. As illustrated in FIG. 1, the conventional microdisplay panel (10) is a technology that combines a Si CMOS semiconductor wafer process with a high-resolution, high-brightness ultra-small display process. The conventional microdisplay panel (10) may have a structure in which a Si CMOS wafer (11) having a crystal plane of 4" or larger (100) equipped with a plurality of CMOS electrode pads (12), a microLED electrode pad (14), and a transparent wafer (13) having 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 LCoS (LC on Si), OLED (organic light-emitting diode) based OLEDoS (OLED on Si), and ultra-small microLED based LEDoS (LED on Si) having a pixel size of less than 5㎛. In the case of VR with a low pixel density display, development and mass production are centered on LCoS and OLEDoS. However, with the advancement of metaverse implementation technology, there is a growing need for lightweight AR, MR, and XR devices equipped with high pixel density microdisplay panels. In response to this need, there is an urgent need to develop LEDoS technology, which is attracting attention as a theoretically ideal solution based on the superiority of inorganic properties, but a microdisplay panel platform for this has not yet been established. When applied to XR devices, microLED-based LEDoS with pixel sizes of less than 5㎛ offers the advantages of excellent power-to-performance ratio and short response speed. Additionally, it has a long lifespan due to its inorganic composition and allows for efficient power usage, which helps mitigate heat and enables long battery life. In particular, 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. Therefore, LEDoS, which has a nanosecond response speed, is considered the most suitable for XR devices compared to LCoS and OLEDoS, which have microsecond response speeds. Furthermore, it is assessed that the biggest reason LEDoS is attracting attention in AR, MR, and XR devices, unlike VR, is due to its brightness and luminous efficiency. Given the nature of smart glasses that can be worn regardless of location, high brightness is an essential condition to ensure normal operation even in outdoor environments such as sunlight. Theoretically, microLEDs support brightness levels of tens to millions of nits, and since microLEDs are inorganic rather than organic, they also have the advantage of high luminous efficiency. However, despite the aforementioned advantages, the biggest reason why ultra-small microLED-based LEDoS with pixel sizes of less than 5㎛ has not established itself as a key component of XR devices is the difficulty of mass production. In other words, since LEDoS requires fixing millions of ultra-small microLEDs onto a Si CMOS wafer, the process difficulty is high and the yield is very low, leading to increased manufacturing costs and high component prices. This is reflected in the end consumer price, resulting in high-priced XR devices, making it difficult to meet market demand. Meanwhile, as illustrated in Fig. 2, the development of LEDoS with microLED light sources of group 3-5 compounds (GaN, GaP, etc.) has been carried out through traditional approaches such as ① monolithic integration of a wafer (or unit die) composed of a microLED array on a CMOS wafer, or ② hybridization between wafers (or unit dies) on a CMOS wafer or on blue, green, and red light source wafers (or unit dies) on which a microLED array is fabricated. One of the biggest obstacl