METHOD OF MANUFACTURING DISPLAY DEVICE

One aspect of the present disclosure provides a method of manufacturing a display device, including: a process of aligning a first wafer on which a plurality of first LEDs, a plurality of alignment keys, and a reference member are disposed with a donor substrate; a process of transferring the plurality of first LEDs and the reference member on the first wafer to the donor substrate; and a process of aligning a second wafer on which a plurality of second LEDs is disposed with the donor substrate based on the reference member. Therefore, a relative position between the plurality of second LEDs of the second wafer and the plurality of first LEDs of the donor substrate may be precisely aligned based on the reference member that maintains a predetermined interval from the plurality of first LEDs.

TECHNICAL FIELD

The present disclosure relates to a method of manufacturing a display device, and more particularly, to a method of manufacturing a display device with improved alignment accuracy of a plurality of LEDs.

BACKGROUND ART

Display devices used for a computer monitor, a TV, a mobile phone, etc. include an organic light emitting display (OLED) device that emits light by itself, a liquid crystal display (LCD) device that requires a separate light source, etc.

As the display devices have been increasingly applied to diverse fields such as a computer monitor, a TV, and a personal mobile device, display devices having a large display area and a reduced volume and weight have been studied.

In addition, in recent years, a display device including an LED has attracted attention as a next generation display device. The LED may be made of an inorganic material, not an organic material, and thus may have excellent reliability and a longer lifetime than a liquid crystal display device or an organic light emitting display device. Further, the LED may have a fast-emitting speed as well as excellent luminous efficiency, excellent impact resistance, excellent stability, and the ability to display a high-brightness image.

DISCLOSURE

Technical Problem

The present disclosure is directed to providing a method of manufacturing a display device with improved alignment accuracy of a plurality of LEDs in a primary transfer process of transferring the plurality of LEDs to a donor substrate from a wafer and a secondary transfer process of transferring the plurality of LEDs to a display panel from the donor substrate.

Also, the present disclosure is directed to providing a method of manufacturing a display device with improved alignment accuracy of a plurality of LEDs without limitation to the size of the plurality of LEDs.

Further, the present disclosure is directed to providing a method of manufacturing a display device with a high resolution.

Furthermore, the present disclosure is directed to providing a method of manufacturing a display device with reduced process time and cost by simplifying a transfer process of an alignment key during a primary transfer process.

Moreover, the present disclosure is directed to providing a method of manufacturing a display device with reduced process time and cost by shortening a secondary transfer process in which a red LED, a green LED and a blue LED respectively corresponding to a plurality of sub-pixels are transferred to a display panel at a time.

Besides, the present disclosure is directed to providing a method of manufacturing a display device with improved productivity and yield by simplifying a primary transfer process and a secondary transfer process and precisely aligning a plurality of LEDs.

Technical Solution

One aspect of the present disclosure provides a method of manufacturing a display device, including: a process of aligning a first wafer on which a plurality of first LEDs, a plurality of alignment keys, and a reference member are disposed with a donor substrate; a process of transferring the plurality of first LEDs and the reference member on the first wafer to the donor substrate; and a process of aligning a second wafer on which a plurality of second LEDs is disposed with the donor substrate based on the reference member. Therefore, a relative position between the plurality of second LEDs of the second wafer and the plurality of first LEDs of the donor substrate may be precisely aligned based on the reference member that maintains a predetermined interval from the plurality of first LEDs.

Another aspect of the present disclosure provides a method of manufacturing a display device, including: a process of aligning a first wafer on which a reference member and a plurality of first LEDs are disposed with a donor substrate; a process of transferring the plurality of first LEDs and the reference member of the first wafer to the donor substrate; a process of aligning a second wafer on which a plurality of second LEDs is disposed with the donor substrate based on the reference member transferred onto the donor substrate; a process of transferring the plurality of second LEDs of the second wafer to the donor substrate; a process of aligning a third wafer on which a plurality of third LEDs is disposed with the donor substrate based on the reference member transferred onto the donor substrate; and a process of transferring the plurality of third LEDs of the third wafer to the donor substrate. Therefore, a decrease in alignment accuracy of a plurality of LEDs caused by an alignment error in the process may be minimized by aligning the second wafer and the third wafer based on the reference member first transferred onto the donor substrate.

Advantageous Effects

According to the present disclosure, a relative position of a plurality of LEDs is aligned during a first transfer. Thus, an interval between the plurality of LEDs can be precisely aligned so that the plurality of LEDs corresponds to a plurality of sub-pixels, respectively.

According to the present disclosure, a plurality of micro-sized LEDs can be easily aligned.

According to the present disclosure, a decrease in yield caused by an alignment error in the process during a transfer of a plurality of LEDs can be minimized.

According to the present disclosure, a display device with a high resolution can be easily manufactured.

According to the present disclosure, a primary transfer process and a secondary transfer process are shortened. Thus, the process time and cost for manufacturing a display device can be reduced and productivity can be improved.

MODES OF THE INVENTION

Hereinafter, the present disclosure will be described in detail with reference to accompanying drawings.

FIG.1is a plan view of a display device according to an exemplary embodiment of the present disclosure. InFIG.1, for convenience of description, only a display panel PNA and a plurality of pixels POX among various components of a display device100are illustrated.

The display panel PN is configured to display an image and includes a display area AA and a non-display area NA.

The display panel PN includes the display area AA and the non-display area NA.

The display area AA is an area where an image is displayed. The plurality of pixels PX for displaying an image and a circuit unit for driving the plurality of pixels PX may be disposed in the display area AA. The circuit unit may include various thin film transistors, capacitors and lines for driving the pixels PX. For example, the circuit unit may be composed of various components such as a driving thin film transistor, a switching thin film transistor, a storage capacitor, a gate line, a data line, and the like, but is not limited thereto.

The non-display area NA is an area where an image is not displayed. In the non-display area NA, various lines, driving ICs, and the like for driving the pixels PX disposed in the display area AA are disposed. For example, various driving ICs such as a gate driver IC and a data driver IC may be disposed in the non-display area NA.

Meanwhile, althoughFIG.1illustrates that the non-display area NA surrounds the display area AA, the non-display area NA may be an area extending from one side of the display area AA, but is not limited thereto.

The plurality of pixels PX is disposed in the display area AA of the display panel PN. Each of the plurality of pixels PX may be composed of a plurality of sub-pixels. Each of the plurality of sub-pixels is an individual unit that emits light and is provided with a light emitting diode and a driving circuit. For example, the plurality of pixels PX may include a red sub-pixel, a green sub-pixel, and a blue sub-pixel, but is not limited thereto. The plurality of pixels PX may further include a white sub-pixel.

Hereinafter, the plurality of pixels PX will be described in detail with reference toFIG.2andFIG.3.

FIG.2is a schematic plan view of a plurality of pixels PX of the display device according to an exemplary embodiment of the present disclosure.FIG.3is a schematic cross-sectional view of the plurality of sub-pixels of the display device according to an exemplary embodiment of the present disclosure. Specifically.FIG.3is a cross-sectional view of a first sub-pixel among a plurality of sub-pixels of the display device100according to an exemplary embodiment of the present disclosure.

Referring toFIG.2, each of the plurality of pixels PX includes a plurality of sub-pixels. Specifically, each of the plurality of pixels PX may include a first sub-pixel, a second sub-pixel, and a third sub-pixel. The first sub-pixel, the second sub-pixel and the third sub-pixel may emit light of different colors from each other.

In each pixel PX, the first sub-pixel, the second sub-pixel, and the third sub-pixel may be disposed in a line. Further, the first sub-pixel, the second sub-pixel and the third sub-pixel may be disposed to be equally spaced apart from each other. Based on the second sub-pixel, the first sub-pixel may be disposed on one side of the second sub-pixel and the third sub-pixel may be disposed on the other side of the second sub-pixel. Furthermore, an interval between the first sub-pixel and the second sub-pixel may be equal to an interval between the second sub-pixel and the third sub-pixel. For example, in each pixel PX, the center of the first sub-pixel and the center of the second sub-pixel may be disposed at a first interval IN1and the center of the first sub-pixel and the center of the third sub-pixel may be disposed at a second interval IN2which is twice the first interval IN1.

An LED ED is disposed in each of the plurality of sub-pixels. The plurality of LEDs ED serves as light emitting diodes to emit light when a voltage is applied. The plurality of LEDs ED may include LEDs ED that emit red light, green light, and blue light, and light of various colors including white may be implemented by combination thereof.

The plurality of LEDs ED includes a first LED130, a second LED140and a third LED150. The first LED130is disposed in the first sub-pixel, the second LED140is disposed in the second sub-pixel and the third LED150is disposed in the third sub-pixel.

Meanwhile, when the plurality of LEDs ED emits light of different colors from each other, some of the plurality of LEDs ED may be red LEDs emitting red light, some of the plurality of LEDs ED may be green LEDs emitting green light, and the others may be blue LEDs emitting blue light. Since the plurality of LEDs ED emits light of different colors from each other, a member such as a light conversion layer may be omitted. Hereinafter, it is assumed that the first LED130among the plurality of LEDs ED is a red LED, the second LED140is a green LED, and the third LED150is a blue LED.

However, the plurality of LEDs ED may further include a white LED that implements a white sub-pixel, and the type and number of LEDs ED disposed in a plurality of sub-pixels forming a pixel PX may vary depending on embodiments.

Referring toFIG.3, a substrate110is a support member for supporting other components of the display device100and may be made of an insulating material. For example, the substrate110may be made of glass, resin, or the like. Further, the substrate110may be configured to include a polymer or plastic such as polyimide PT or may be made of a material having flexibility.

A driving transistor120is disposed on the substrate110of the display panel PN. The driving transistor120may be used as a driving element of the display device100. The driving transistor120includes a gate electrode121, an active layer122, a source electrode123, and a drain electrode124.

The gate electrode121is disposed on the substrate110. The gate electrode121may be made of a conductive material, for example, copper (Cu), aluminum (Al), molybdenum (Mo), titanium (Ti), or an alloy thereof, but is not limited thereto.

A gate insulating layer111is disposed on the gate electrode121. The gate insulating layer111is a layer for insulating the gate electrode121and the active layer122and may be made of an insulating material. For example, the gate insulating layer111may be configured by a single layer or a multilayer of silicon oxide (SiOx) or silicon nitride (SiNx), but is not limited thereto.

The active layer122may be disposed on the gate insulating layer111. For example, the active layer122may be made of an oxide semiconductor, an amorphous silicon or a poly silicon, but is not limited thereto.

The source electrode123and the drain electrode124are disposed to be spaced apart from each other on the active layer122. The source electrode123and the drain electrode124may be electrically connected to the active layer122. The source electrode123and the drain electrode124may be made of a conductive material, such as copper (Cu), aluminum (Al), molybdenum (Mo), titanium (Ti) or an alloy thereof, but are not limited thereto.

Meanwhile, in the present specification, the driving transistor120is illustrated as having a structure in which the gate electrode121is disposed at the bottom, the active layer122is disposed on the gate electrode121, and the source electrode123and the drain electrode124are disposed on the active layer122, but is not limited thereto.

A common line CL is disposed on the gate insulating layer111. The common line CL may transmit a common power, supplied from the outside to the plurality of LEDs ED of the plurality of sub-pixels. The common line CL may be made of the same material and formed by the same process as, for example, the source electrode123and the drain electrode124of the driving transistor120. However, the material and placement of the common line CL are not limited thereto.

A first insulating layer112is disposed on the driving transistor120and the common line CL. The first insulating layer112is disposed on the driving transistor120to protect the driving transistor120. The first insulating layer112may be made of an organic material such as benzocyclobutene or photo acryl.

The first LED130is disposed on the first insulating layer112. The first LED130may be electrically connected to the source electrode123or the drain electrode124of the driving transistor120through a contact hole formed in the first insulating layer112. Meanwhile, inFIG.3, although the first LED130is illustrated as being disposed on the patterned first insulating layer112, the first LED130may not be patterned and may be disposed on the first insulating layer112with a flat top surface, but is not limited thereto.

The plurality of LEDs ED may be configured to have various structures, such as a lateral type, a vertical type, and a flip chip. The lateral LED includes an n-type electrode and a p-type electrode horizontally disposed on both sides of an emission layer. The vertical LED includes an n-type electrode and a p-type electrode disposed on and below an emission layer. The flip chip LED has substantially the same structure as the lateral LED. The lateral LED includes the n-type electrode and the p-type electrode horizontally disposed on the emission layer, whereas the flip chip LED includes the n-type electrode and the p-type electrode horizontally disposed below the emission layer. Hereinafter, it is assumed that the plurality of LEDs ED has a lateral structure, but the type of the plurality of LEDs ED is not limited thereto.

Meanwhile, the LEDs may be manufactured by a process separate from a TFT array process of the display panel PN. For example, the plurality of LEDs ED may be formed on a wafer200made of a material such as sapphire and disposed on the display panel PN on which the driving transistor120and various lines are disposed through a transfer process.

The first LED130includes a first p-type semiconductor layer131, a first emission layer132, a first n-type semiconductor layer133, a first p-type electrode134, and a first n-type electrode135.

The first n-type semiconductor layer133is disposed on the first insulating layer112, and the first p-type semiconductor layer131is disposed on the first n-type semiconductor layer133. The first p-type semiconductor layer131and the first n-type semiconductor layer133may be formed by implanting n-type or p-type impurities into gallium nitride (GaN). For example, the first p-type semiconductor layer131may be a layer formed by implanting p-type impurities into GaN and the first n-type semiconductor layer133may be a layer formed by implanting n-type impurities into GaN, but is not limited thereto. The p-type impurities may be magnesium (Mg), zinc (Zn), beryllium (Be), etc. and the n-type impurities may be silicon (Si), germanium (Ge), tin (Sn), etc., but are not limited thereto.

The first emission layer132is disposed between the first p-type semiconductor layer131and the first n-type semiconductor layer133. The first emission layer132may emit light by receiving holes and electrons from the first p-type semiconductor layer131and the first n-type semiconductor layer133. The first emission layer132may be a single layer or a multi-quantum well (MQW) structure. For example, the first emission layer132may be made of indium gallium nitride (InGaN) or gallium nitride (GaN), but is not limited thereto.

The first p-type electrode134is disposed on the first p-type semiconductor layer131, and the first n-type electrode135is disposed on the first n-type semiconductor layer133. The first p-type electrode134may be electrically connected to the first p-type semiconductor layer131, and the first n-type electrode135may be electrically connected to the first n-type semiconductor layer133.

A second insulating layer113is disposed on the first LED130and the first insulating layer112. The second insulating layer113may be disposed on the plurality of LEDs ED to protect the plurality of LEDs ED. The second insulating layer113may be made of an organic material such as benzocyclobutene or photo acryl.

A first connection electrode CE1and a second connection electrode CE2are disposed on the second insulating layer113. The first connection electrode CE1may electrically connect the driving transistor120and the first LED130through a contact hole of the first insulating layer112and the second insulating layer113. For example, the first connection electrode CE1may electrically connect the drain electrode124of the driving transistor120and the first p-type electrode134of the first LED130. The first connection electrode CE1may be made of a transparent metal oxide such as indium tin oxide (ITO), indium gallium zinc oxide (IGZO), or indium gallium oxide (IGO), but is not limited thereto.

The second connection electrode CE2may electrically connect the common line CL and the first LED130through the contact hole of the first insulating layer112and the second insulating layer113. For example, the second connection electrode CE2may electrically connect the common line CL and the first n-type electrode135of the first LED130. The second connection electrode CE2may be made of a transparent metal oxide such as indium tin oxide (ITO), indium gallium zinc oxide (IGZO), or indium gallium oxide (IGO), but is not limited thereto.

A buffer layer114is disposed on the first connection electrode CE1and the second connection electrode CE2. The buffer layer114may be disposed on the entire surface of the display panel PN to protect a circuit including the plurality of LEDs ED and the driving transistor120from an external impact. The buffer layer114may be made of, for example, optical clear adhesive (OCA) or optical clear resin (OCR), but is not limited thereto.

Meanwhile, although not shown in the drawings, a reflective layer disposed to overlap with the plurality of LEDs ED may be further disposed. The reflective layer is disposed to overlap with the plurality of LEDs ED and thus may reflect light emitted from the plurality of LEDs ED to the outside of the display device100and improve the light efficiency of the display device100.

Hereinafter, a method of manufacturing the display device100according to an exemplary embodiment of the present disclosure will be described with reference toFIG.4throughFIG.7.

FIG.4is a process flowchart for explaining a method of manufacturing a display device according to an exemplary embodiment of the present disclosure.FIG.5AthroughFIG.5Lare schematic process diagrams for explaining the method of manufacturing a display device according to an exemplary embodiment of the present disclosure. Specifically,FIG.4is a process flowchart for explaining a primary transfer process by which the plurality of LEDs ED on the wafer200is transferred to a donor substrate300, andFIG.5AthroughFIG.5Lare schematic process diagrams for explaining the primary transfer process. The cross-sectional views ofFIG.5C,FIG.5F,FIG.5G,FIG.5I,FIG.5JandFIG.5Kare taken along line A-A′ ofFIG.5B.

The plurality of LEDs ED on the wafer200may be transferred to the donor substrate300by performing the primary transfer process, and the plurality of LEDs ED on the donor substrate300may be transferred to the display panel PN by performing a secondary transfer process. Accordingly, the manufacturing process of the display device100may be completed by transferring the plurality of LEDs ED from the wafer200to the donor substrate300and from the donor substrate300to the display panel PN. Here, in the method of manufacturing the display device100according to an exemplary embodiment of the present disclosure, it is assumed that a reference member for aligning the donor substrate300with the wafer200and the donor substrate300with the display panel PN is a second alignment key AK2transferred to the donor substrate300from a first wafer210together with the first LED130.

Hereinafter, the primary transfer process S100will be described with reference toFIG.4andFIG.5AthroughFIG.5L.

Referring toFIG.4andFIG.5Atogether, the wafer200is a substrate on which the plurality of LEDs ED is formed. A material such as gallium nitride (GaN) or indium gallium nitride (InGaN) forming the plurality of LEDs ED is formed on the wafer200to grow a crystal layer. The crystal layer is cut into individual chips and electrodes are formed to form the plurality of LEDs ED. The wafer200may be made of sapphire, silicon carbide (SiC), gallium nitride (GaN), zinc oxide (ZnO), or the like, but is not limited thereto.

In this case, the plurality of LEDs ED emitting light of the same color or the plurality of LEDs ED emitting light of different colors may be formed on one wafer200. Hereinafter, it is assumed that the plurality of LEDs ED emitting light of the same color is formed on one wafer200.

The wafer200includes an active area200A and an outer area200B. The active area200A is an area where the plurality of LEDs ED is formed, and the outer area200B disposed outside the active area200A is an area where a plurality of alignment keys AK is disposed.

The plurality of alignment keys AK includes a first alignment key AK1and a second alignment key AK2. The first alignment key AK1and the second alignment key AK2may be disposed adjacent to an edge of the wafer200in the outer area200B. However, the first alignment key AK1and the second alignment key AK2may be disposed at positions other than the edge of the wafer200depending on the design, and the number of first alignment keys AK1and second alignment keys AK2may also be variously designed.

The first alignment key AK1is a component used to align the wafer200and the donor substrate300. The first alignment key AK1is a mark for adjusting alignment and parallelism between the wafer200and the donor substrate300when the plurality of LEDs ED of the wafer200is transferred to the donor substrate300. For example, alignment and parallelism between the wafer200and the donor substrate300may be adjusted by aligning the first alignment key AK1of the wafer200and an alignment protrusion332of the donor substrate300.

The second alignment key AK2is a component used to align the donor substrate300and the display panel PN. The second alignment key AK2may be transferred to the donor substrate300together with the plurality of LEDs ED when the plurality of LEDs ED of the wafer200is transferred to the donor substrate300. Then, alignment and parallelism between the donor substrate300and the display panel PN may be adjusted by using the second alignment key AK2on the donor substrate300.

The first alignment key AK1and the second alignment key AK2may be formed together when the plurality of LEDs ED is formed, or may be formed by a separate process from the plurality of LEDs ED. If the first alignment key AK1and the second alignment key AK2are formed together with the plurality of LEDs ED, the first alignment key AK1and the second alignment key AK2may be made of the same materials as at least some of the materials forming the plurality of LEDs ED. However, the materials and forming processes of the first alignment key AK1and the second alignment key AK2may be variously configured depending on the design, but are not limited thereto.

The shapes and sizes of the first alignment key AK1and the second alignment key AK2may be variously configured. In order to identify the first alignment key AK1and the second alignment key AK2disposed in the outer area200B, the first alignment key AK1may have a different shape or size from the second alignment key AK2. For example, the first alignment key AK1may have a larger size than the second alignment key AK2, but is not limited thereto.

Referring toFIG.5B, the donor substrate300includes a base layer310, an adhesive layer320, a resin layer330, a plurality of protrusions331, and a plurality of alignment protrusions332.

The base layer310is configured to support various components included in the donor substrate300and may be made of a more rigid material than at least the resin layer330in order to minimize bending of the resin layer330. The base layer310may be disposed under the resin layer330to support the resin layer330, the plurality of protrusions331, and the plurality of alignment protrusions332. For example, the base layer310may be configured to include a polymer or plastic and may be made of poly carbonate (PC) or polyethylene terephthalate (PET), but is not limited thereto.

Meanwhile, an identification pattern340and an orientation pattern350may be disposed on a portion of the base layer310protruding toward the outside of the resin layer330.

An identification pattern340is a pattern formed on the base layer310to identify the donor substrate300. A plurality of donor substrates300may be managed using unique identification patterns340given to the respective donor substrates300. The identification pattern340may be disposed on an upper surface or a rear surface of the base layer310and may be formed by a printing method or a laser engraving method. For example, the identification pattern340may be an ID composed of numbers or characters or a barcode, but is not limited thereto. Meanwhile, inFIG.5B, although a single identification pattern340is illustrated as being formed on the lower left side of the donor substrate300, the number and placement of identification patterns are not limited thereto.

An orientation pattern350is a pattern formed on the base layer310to distinguish the orientation of the donor substrate300. For example, when the donor substrate300is put into process equipment, if the donor substrate300is put in the opposite direction, the LEDs ED may be transferred to a different position from the designed position, or a defect may occur. Accordingly, the orientation pattern350may be disposed on any one portion of the base layer310in order to distinguish the orientation of the donor substrate300. The orientation pattern350may be formed by a printing method or a laser engraving method or may be formed by chamfering an edge of the base layer310, but is not limited thereto.

The resin layer330is disposed on the base layer310. During the transfer process, the resin layer330may support the plurality of protrusions331to which the plurality of LEDs ED is attached. The resin layer330may be made of a polymer resin having viscoelasticity. For example, the resin layer330may be made of poly di methyl siloxane (PDMS), poly urethane acrylate (PUA), polyethylene glycol (PEG), poly methyl meth acrylate (PMMA), poly styrene (PS), epoxy resin, urethane resin, acrylic resin, etc., but is not limited thereto.

The resin layer330includes a transfer area330A and a non-transfer area330B.

The transfer area330A is an area where the plurality of protrusions331is disposed. The transfer area330A is an area where the plurality of protrusions331to which the plurality of LEDs ED is attached is disposed. The transfer area330A may be disposed to overlap with at least a portion of the wafer200or the display panel PN during a transfer process.

The non-transfer area330B is an area where the plurality of alignment protrusions332is disposed. The plurality of LEDs ED of the wafer200may not be transferred to the non-transfer area330B, but the second alignment key AK2of the wafer200may be transferred to the non-transfer area330B.

The plurality of protrusions331may be protrusions331on which the plurality of LEDs ED is disposed and may be extended from one surface of the resin layer330. The plurality of protrusions331may be formed integrally with the resin layer330, and may be made of a polymer material having viscoelasticity like the resin layer330. For example, the plurality of protrusions331may be made of poly di methyl siloxane (PDMS), poly urethane acrylate (PUA), polyethylene glycol (PEG), poly methyl meth acrylate (PMMA), poly styrene (PS), epoxy resin, urethane resin, acrylic resin, etc., but is not limited thereto.

The plurality of LEDs ED may be temporarily attached to upper surfaces of the plurality of protrusions331. The plurality of LEDs ED formed on the wafer200may be transferred to the upper surfaces of the plurality of protrusions331and may temporarily continue to be attached to the upper surfaces of the plurality of protrusions331before being transferred to the display panel PN.

In this case, the plurality of protrusions331may be disposed at the same interval as the interval between the plurality of sub-pixels. For example, when the plurality of LEDs ED is transferred to the display panel PN, the plurality of LEDs ED is transferred corresponding to the plurality of sub-pixels, respectively. If the plurality of LEDs ED transferred to the donor substrate300is transferred at a time, the plurality of LEDs ED on the donor substrate300needs to be disposed corresponding to the plurality of sub-pixels, respectively. In this case, the plurality of LEDs ED transferred to the display panel PN at once may be transferred corresponding to the plurality of sub-pixels, respectively. However, the placement and interval of the plurality of protrusions331may vary depending on the design, but are not limited thereto.

The plurality of protrusions331may have a larger size than the plurality of LEDs ED. The upper surfaces of the plurality of protrusions331are formed larger in size than the plurality of LEDs ED. Thus, even if an alignment error between the donor substrate300and the wafer200occurs, the plurality of LEDs ED may be mounted on the plurality of protrusions331. Accordingly, in consideration of the alignment error between the wafer200and the donor substrate300, the upper surfaces of the plurality of protrusions331may be formed larger in size than the plurality of LEDs ED.

The plurality of alignment protrusions332is disposed in the non-transfer area330B. The plurality of alignment protrusions332includes a plurality of first alignment protrusions333and a plurality of second alignment protrusions334.

The plurality of first alignment protrusions333is used to align the wafer200and the donor substrate300. The plurality of first alignment protrusions333may be disposed corresponding to the first alignment key AK1of the wafer200. For example, alignment and parallelism between the wafer200and the donor substrate300may be adjusted by aligning the first alignment key AK1of the first wafer210and the first alignment protrusion333of the donor substrate300. In this case, the first alignment protrusion333may have a different shape or size from the first alignment key AK1to facilitate identification. For example, any one of the first alignment protrusion333and the first alignment key AK1may have a donut shape with a hole in the middle, and the other one may have a circular shape overlapping with the hole.FIG.5AandFIG.5Billustrate that the first alignment key AK1of the wafer200and the first alignment protrusion333of the donor substrate300are circular, but the shapes of the first alignment key AK1and the first alignment protrusion333are not limited thereto.

The second alignment protrusion334may be disposed corresponding to the second alignment key AK2of the wafer200. For example, after aligning the first alignment key AK1of the wafer200and the first alignment protrusion333of the donor substrate300to align the wafer200and the donor substrate300, the plurality of LEDs ED of the wafer200may be transferred to the plurality of protrusions331of the donor substrate300and the second alignment key AK2of the wafer200may be transferred to the second alignment protrusion334of the donor substrate300. In this case, the second alignment key AK2transferred to the donor substrate300may be used later to align the display panel PN with the donor substrate300.

Meanwhile, although not shown in the drawings, a plurality of protrusions other than the plurality of alignment protrusions332may be further disposed in the non-transfer area330B. Specifically, in order to minimize deformation of the resin layer330and the plurality of protrusions331in the transfer area330A caused by an impact applied to the donor substrate300during a transfer process, a plurality of protrusions may be further disposed in the non-transfer area330B. For example, when the plurality of LEDs ED is transferred onto the donor substrate300after the wafer200is bonded to the donor substrate300, the plurality of LEDs ED may apply an impact to the donor substrate300while moving onto the donor substrate300. When the impact is applied to the donor substrate300, the positions or shapes of the resin layer330and the plurality of protrusions331in the transfer area330A may be changed. In this case, the plurality of protrusions in the non-transfer area330B disposed to surround the transfer area330A may continue to be bonded to the wafer and minimize deformation of the resin layer330and the plurality of protrusions331in the transfer area330A.

Meanwhile, the plurality of protrusions331may not be disposed in the donor substrate300, and the plurality of LEDs ED may be directly transferred onto the resin layer330. That is, the donor substrate300may not include the separate protrusion331. The structure of the donor substrate300may vary depending on the shape, placement, and transfer method of the plurality of LEDs ED, but is not limited thereto. Hereinafter, for convenience of description, it is assumed that the donor substrate300includes the plurality of protrusions331and the plurality of LEDs ED is transferred to the plurality of protrusions331, respectively.

The adhesive layer320is disposed between the resin layer330and the base layer310. The adhesive layer320bonds the resin layer330to the display panel PN. The adhesive layer320may be made of a material having an adhesive property, for example, optical clear adhesive (OCA), pressure sensitive adhesive (PSA), or the like, but is not limited thereto.

However, the adhesive layer320may be omitted depending on the design. For example, the resin layer330may be formed by directly coating a material forming the resin layer330on the base layer310and then curing the material. In this case, since the resin layer330may be attached to the base layer310even if the adhesive layer320is not disposed, the adhesive layer320may be omitted depending on the design, but is not limited thereto.

ReferringFIG.5CthroughFIG.5Etogether, the first wafer210on which a plurality of first LEDs130is formed and the donor substrate300are put into the process equipment (S110). Then, the first wafer210and the donor substrate300in the process equipment are aligned (S111). In a state where the first wafer210and the donor substrate300are disposed such that the plurality of first LEDs130on the first wafer210and the plurality of protrusions331of the donor substrate300face each other, the first wafer210and the donor substrate300may be aligned. Specifically, the first wafer210and the donor substrate300may be aligned by aligning the center of the first alignment key AK1of the first wafer210with the center of the first alignment protrusion333of the donor substrate300.

After the alignment between the first wafer210and the donor substrate300is completed, the plurality of first LEDs130of the first wafer210is transferred to the donor substrate300(S112). In a state where the first wafer210and the donor substrate300are disposed to face each other, a laser may be selectively irradiated only to the first LED130to be transferred to the donor substrate300among the plurality of first LEDs130. The first LED130irradiated with the laser may be detached from the first wafer210and then attached to the plurality of protrusions331of the donor substrate300.

In this case, at least some of the plurality of second alignment keys AK2of the wafer200may also be transferred to the donor substrate300. In a state where the first wafer210and the donor substrate300are disposed to face each other, a laser may be selectively irradiated only to some second alignment keys AK2to be transferred to the donor substrate300among the plurality of second alignment keys AK2. The second alignment keys AK2irradiated with the laser may be detached from the first wafer210and then attached to the second alignment protrusions334of the donor substrate300.

Referring toFIG.5D, after the transfer of the plurality of first LEDs130and the second alignment keys AK2is completed, some of the first LEDs130and some of the second alignment keys AK2, which are not transferred to the donor substrate300, may remain on the first wafer210. Further, the first LEDs130and second alignment keys AK2remaining on the first wafer210may be transferred onto another donor substrate300and then transferred to the display panel PN.

Referring toFIG.5E, the plurality of first LEDs130may be transferred to the protrusions331at positions corresponding to the first sub-pixels among the plurality of protrusions331of the donor substrate300. The plurality of first LEDs130may be LEDs ED disposed in the first sub-pixels. Further, the plurality of protrusions331of the donor substrate300is disposed corresponding to the sub-pixels. Accordingly, the plurality of first LEDs130is transferred only onto some protrusions331to be aligned corresponding to the first sub-pixels in a secondary transfer process to be described later among the plurality of protrusions331of the donor substrate300. Thus, the plurality of first LEDs130may be transferred to the first sub-pixel of the display panel PN at once.

Meanwhile, an interval between a specific first LED130and the second alignment key AK2among the plurality of first LEDs130transferred to the donor substrate300is constant. Specifically, an interval between a specific second alignment key AK2and the first LED130disposed at the shortest distance on the first wafer210and an interval between the specific second alignment key AK2and the first LEDs130disposed at the shortest distance on the donor substrate300may be constant. For example, the second alignment key AK2disposed at an upper left end among the four second alignment keys AK2transferred to the donor substrate300and the first LED130disposed at the upper left end to be closest thereto may have an interval of D1on the first wafer210and may also have the interval of D1on the donor substrate300. Further, the second alignment key AK2disposed at an upper right end among the four second alignment keys AK2transferred to the donor substrate300and the first LED130disposed at the upper right end to be closest thereto may have an interval of D2on the first wafer210and may also have the interval of D2on the donor substrate300. That is, when the plurality of first LEDs130and the plurality of second alignment keys AK2are transferred, the plurality of second alignment keys AK2may be transferred at a predetermined interval from the respective first LEDs130disposed at the shortest distance.

Therefore, if the plurality of second alignment keys AK2is disposed to deviate from their original positions on the plurality of second alignment protrusions334, the plurality of first LEDs130at a predetermined interval from the plurality of second alignment keys AK2, respectively, may also be disposed to deviate from their original positions on the plurality of protrusions331. Accordingly, the positions of the plurality of first LEDs130may be easily identified through the second alignment keys AK2.

After the plurality of first LEDs130of the first wafer210is transferred to the donor substrate300, the first wafer210and the donor substrate300are detached (S113), and the donor substrate300to which the first LEDs130are transferred is discharged from the process equipment (S114).

Then, the donor substrate300on which the first LEDs130are disposed and a second wafer220on which a plurality of second LEDs140is formed are put into the process equipment (S120). Thereafter, the second wafer220and the donor substrate300are aligned (S121) and the plurality of second LEDs140is transferred to the donor substrate300(S122).

Referring toFIG.5F, in a state where the second wafer220and the donor substrate300are disposed such that the plurality of second LEDs140on the second wafer220and the plurality of protrusions331of the donor substrate300face each other, the second wafer220and the donor substrate300may be aligned.

In this case, the first wafer210and the donor substrate300are aligned based on the first alignment key AK1and the first alignment protrusion333. However, the second wafer220and the donor substrate300may be aligned based on at least some of the plurality of second alignment keys AK2transferred to the donor substrate300from the first wafer210.

Specifically, when the donor substrate300on which the plurality of first LEDs130and the plurality of second alignment keys AK2are disposed is aligned with the second wafer220, they may be aligned based on one or more second alignment keys AK2among the plurality of second alignment keys AK2disposed on the donor substrate300and any one component among the components of the second wafer220. For example, the second wafer220and the donor substrate300may be aligned based on the plurality of second alignment keys AK2transferred to the donor substrate300from the first wafer210and the first alignment keys AK1or the second alignment keys AK2of the second wafer220. Alternatively, the second wafer220and the donor substrate300may be aligned based on the plurality of second alignment keys AK2transferred to the donor substrate300from the first wafer210and some of the plurality of second LEDs140of the second wafer220.

As described above, an interval between the second alignment key AK2and the first LED130disposed on the donor substrate300is constant, and, thus, the position of the first LED130may be identified through the second alignment key AK2. Accordingly, when the second wafer220and the donor substrate300are aligned based on the second alignment key AK2disposed on the donor substrate300, a relative position between the plurality of first LEDs130on the donor substrate300and the plurality of second LEDs140of the second wafer220may be aligned. For example, the plurality of first LEDs130and the plurality of second LEDs140on the donor substrate300may be transferred to the display panel PN at a time at the first interval IN1which is an interval between the plurality of sub-pixels on the donor substrate300. When the plurality of second LEDs140is transferred to the donor substrate300, the second wafer220and the donor substrate300may be aligned using, as a reference member, the second alignment keys AK2disposed at a predetermined interval, i.e., the first interval IN1, from the plurality of first LEDs130of the donor substrate300.

In this case, only the plurality of second LEDs140may be transferred to the donor substrate300from the second wafer220, but the plurality of second alignment keys AK2may not be transferred. Since different masks or lasers are used for the plurality of second LEDs140and the plurality of second alignment keys AK2during a transfer process, they cannot be transferred simultaneously to the donor substrate300, but may be transferred sequentially. If the plurality of first LEDs130, the plurality of second LEDs140, and a plurality of third LEDs150are transferred to respective donor substrates300, the plurality of second alignment keys AK2may be transferred to each of the donor substrates300to align the display panel PN and the donor substrate300. However, in the method of manufacturing a display device according to an exemplary embodiment of the present disclosure, the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150are transferred to the same donor substrate300and the second alignment keys AK2transferred together with the plurality of first LEDs130are already disposed on the donor substrate300. Thus, the second alignment keys AK2of the second wafer220or a third wafer230may not be transferred to the donor substrate300. Therefore, the process time for transferring the second alignment keys AK2may be reduced.

Meanwhile, by using the plurality of second alignment keys AK2transferred to the donor substrate300as a reference member for aligning the second wafer220and the donor substrate300, the alignment accuracy of the plurality of LEDs ED may be improved. This will be described later in detail with reference toFIG.8throughFIG.11.

Meanwhile, the first alignment key AK1may be omitted in some wafers200depending on the order of use of the wafers200. For example, after the first wafer210on which the plurality of first LEDs130is formed and the donor substrate300are aligned based on the first alignment key AK1, the plurality of first LEDs130and the second alignment key AK2of the first wafer210may be transferred to the donor substrate300and the second wafer220on which the plurality of second LEDs140is formed and the donor substrate300may be aligned based on the second alignment key AK2transferred to the donor substrate300. In this case, the first alignment key AK1may be omitted in the second wafer220and the third wafer230. However, the plurality of first alignment keys AK1may be disposed in each of the plurality of wafers200regardless of the process order, but is not limited thereto.

Referring toFIG.5G, after the alignment between the second wafer220and the donor substrate300is completed, the second wafer220may be shifted by the first interval IN1. After the second wafer220is shifted by the first interval IN1, i.e., the interval between the plurality of sub-pixels, the plurality of second LEDs140is transferred to the donor substrate300.

If the second wafer220is not shifted and a laser is irradiated to the same position of the second wafer220as that of the first wafer210, the plurality of second LEDs140may be transferred to the protrusions331on which the plurality of first LEDs130is disposed, and the plurality of first LEDs130and the plurality of second LEDs140may interfere with each other. Accordingly, after the second wafer220is shifted by the first interval IN1which is the interval between the sub-pixels, a laser may be irradiated to the second wafer220to transfer the plurality of second LEDs140to the donor substrate300. Further, the second LED140irradiated with the laser may be detached from the second wafer220and attached to the plurality of protrusions331of the donor substrate300.

Referring toFIG.5H, the plurality of second LEDs140may be transferred to the protrusions331at positions corresponding to the second sub-pixels among the plurality of protrusions331of the donor substrate300. The plurality of second LEDs140may be LEDs ED disposed in the second sub-pixels. Thus, the plurality of second LEDs140may be transferred only to some protrusions331to be aligned corresponding to the second sub-pixels among the plurality of protrusions331disposed corresponding to the plurality of sub-pixels.

After the plurality of second LEDs140of the second wafer220is transferred to the donor substrate300, the second wafer220and the donor substrate300are detached (S123) and the donor substrate300to which the second LEDs140are transferred is discharged from the process equipment (S124).

Then, the donor substrate300on which the first LEDs130and the second LEDs140are disposed and the third wafer230on which a plurality of third LEDs150is formed are put into the process equipment (S130). Thereafter, the third wafer230and the donor substrate300are aligned (S131).

Referring toFIG.5I, in a state where the third wafer230and the donor substrate300are disposed such that the plurality of third LEDs150on the third wafer230and the plurality of protrusions331of the donor substrate300face each other, the third wafer230and the donor substrate300may be aligned.

In this case, the first wafer210and the donor substrate300are aligned based on the first alignment key AK1and the first alignment protrusion333. However, the third wafer230and the donor substrate300may be aligned based on some second alignment keys AK2used as a reference for alignment with the second wafer220among the plurality of second alignment keys AK2transferred to the donor substrate300from the first wafer210.

Specifically, when the donor substrate300on which the plurality of first LEDs130, the plurality of second alignment keys AK2, and the plurality of second LEDs140are disposed is aligned with the third wafer230, the third wafer230and the donor substrate300may be aligned based on the second alignment key AK2used for alignment with the second wafer220among the plurality of second alignment keys AK2of the donor substrate300. For example, the third wafer230and the donor substrate300may be aligned based on the second alignment key AK2used for alignment with the second wafer220and the first alignment key AK1or the second alignment key AK2of the third wafer230. Also, for example, the third wafer230and the donor substrate300may be aligned based on the second alignment key AK2used for alignment with the second wafer220and some of the plurality of third LEDs150of the third wafer230.

Referring toFIG.5J, after the alignment between the third wafer230and the donor substrate300is completed, the third wafer230may be shifted by the first interval IN1twice. After the second wafer220is shifted by the first interval IN1, the plurality of second LEDs140is transferred to the donor substrate300. Thus, the third wafer230may be shifted by the first interval IN1twice, i.e., by the second interval IN2, in order to suppress interference with the plurality of first LEDs130and the plurality of second LEDs140on the donor substrate3M). Finally, after the third wafer230is shifted by the second interval IN2in the same direction as the shifted direction of the second wafer220, the plurality of third LEDs150is transferred to the donor substrate300.

Referring toFIG.5LandFIG.5K, the plurality of third LEDs150is transferred to the donor substrate300(S132). The plurality of third LEDs150may be transferred to the protrusions331at positions corresponding to the third sub-pixels among the plurality of protrusions331of the donor substrate300. The plurality of third LEDs150may be LEDs ED disposed in the third sub-pixels. Thus, the plurality of third LEDs150may be transferred only to some protrusions331to be aligned corresponding to the third sub-pixels among the plurality of protrusions331disposed corresponding to the plurality of sub-pixels.

The plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150may be disposed on the donor substrate300at the first interval IN1which is the interval between the plurality of sub-pixels. For example, even if the plurality of first LEDs130and the plurality of second alignment keys AK2are disposed to deviate from the centers of upper surfaces of the plurality of protrusions331and the plurality of second alignment protrusions334, the plurality of second LEDs140and the plurality of third LEDs150to be transferred thereafter are transferred based on the second alignment keys AK2disposed at a predetermined interval from the plurality of first LEDs130. Therefore, the plurality of second LEDs140and the plurality of third LEDs150may be disposed to deviate on the plurality of protrusions331in the same manner as the plurality of first LEDs130. Also, a relative position among the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150may be easily aligned. Accordingly, the relative position among the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150on the donor substrate300may correspond to the plurality of sub-pixels.

After the plurality of third LEDs150of the third wafer230is transferred to the donor substrate300, the third wafer230and the donor substrate300are detached (S133) and the donor substrate300to which the third LEDs150are transferred is discharged from the process equipment (S134).

Meanwhile, it has been described in the present specification that after the second wafer220and the third wafer230, which have been aligned with the donor substrate300, are shifted by a predetermined interval, the plurality of second LEDs140and the plurality of third LEDs150are transferred. However, after the second wafer220and the third wafer230are shifted by a predetermined interval, a relative position between the second and third wafers220and230and the donor substrate300may be aligned again, but is not limited thereto. That is, the relative position between the second and third wafers220and230and the donor substrate300shifted by a predetermined interval may be aligned once more, and, thus, a relative position between the plurality of second LEDs140and the plurality of third LEDs150to be transferred to the donor substrate300and the plurality of first LEDs130on the donor substrate300may be more precisely aligned.

Hereinafter, a secondary transfer process by which the plurality of LEDs ED of the donor substrate300is transferred to the display panel PN will be described with reference toFIG.6andFIG.7.

FIG.6is a process flowchart for explaining a method of manufacturing a display device according to an exemplary embodiment of the present disclosure.FIG.7is a schematic process diagram for explaining the method of manufacturing a display device according to an exemplary embodiment of the present disclosure. Specifically.FIG.6is a flowchart for explaining the secondary transfer process by which the plurality of LEDs ED on the donor substrate300is transferred to the display panel PN, andFIG.7is a schematic process diagram for explaining the secondary transfer process.

Referring toFIG.6andFIG.7, a secondary transfer process (S200) is performed to transfer the plurality of LEDs ED on the donor substrate300to the display panel PN. Accordingly, the manufacturing process of the display device100may be completed. In this case, a circuit, e.g., the driving transistor120and a plurality of lines, for driving the plurality of LEDs ED has been formed on the display panel PN.

The plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150on the donor substrate300are disposed at the same interval in the same placement as the plurality of sub-pixels. Since the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150on the donor substrate300are disposed at the same interval in the same placement as the plurality of sub-pixels, the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150of the donor substrate300may be transferred to the display panel PN at once.

First, the donor substrate300on which the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150are disposed and the display panel PN are input to the process equipment (S210). Then, the donor substrate300and the display panel PN are aligned (S211).

In this case, the donor substrate300and the display panel PN may be aligned based on the second alignment key AK2of the donor substrate300used for alignment with the second wafer220and the third wafer230and an alignment key of the display panel PN.

The plurality of second LEDs140and the plurality of third LEDs150disposed on the donor substrate300are transferred not based on the first alignment protrusion333of the donor substrate300, but based on the second alignment key AK2transferred to the donor substrate300from the first wafer210. That is, an interval between the second alignment key AK2and the plurality of first LEDs130is constant, and an interval of the plurality of second LEDs140and the plurality of third LEDs150, which are transferred to the donor substrate300based on the second alignment key AK2, from the second alignment key AK2may also be constant. Accordingly, the plurality of LEDs ED may be easily transferred corresponding to the plurality of sub-pixels of the display panel PN only when the display panel PN and the donor substrate300are aligned based on the second alignment key AK2.

If the donor substrate300and the display panel PN are aligned based on another component of the donor substrate300, the plurality of second LEDs140and the plurality of third LEDs150may have various intervals from the other component. Therefore, the plurality of second LEDs140and the plurality of third LEDs150may not be transferred to their correct positions when transferred to the display panel PN. For example, when the donor substrate300and the display panel PN are aligned based on the first alignment protrusion333of the donor substrate300, the centers of the upper surfaces of the plurality of protrusions331may be aligned corresponding to the plurality of sub-pixels. However, if the donor substrate300and the display panel PN are aligned based on the first alignment protrusion333when the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150are disposed on the donor substrate300so as to be spaced apart from the centers of the upper surfaces of the plurality of protrusions331, it may be difficult to transfer the plurality of LEDs ED of the donor substrate300to their correct positions in the display panel PN.

Therefore, if the donor substrate300and the display panel PN are aligned based on the second alignment key AK2, which is a reference for aligning a relative position of the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150and has a constant interval from the plurality of LEDs ED, the alignment accuracy for transferring the plurality of LEDs ED to the correct positions may be improved. Therefore, when the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150of the donor substrate300are transferred to the display panel PN, the donor substrate300and the display panel PN may be aligned based on the second alignment key AK2used for alignment with the second wafer220and the third wafer230.

The alignment key of the display panel PN to be aligned with the second alignment key AK2on the donor substrate300may be any one of the components formed on the display panel PN, or may be separately formed and disposed. For example, if the alignment key is any one of the components formed on the display panel PN, a reflective layer overlapping with the plurality of LEDs ED or some of the plurality of wires for driving the plurality of LEDs ED among the components formed on the display panel PN may function as the alignment key. Also, if the alignment key is separately formed and disposed, the alignment key may be a pattern or structure formed on the display panel PN, but is not limited thereto.

Then, after the alignment between the donor substrate300and the display panel PN is completed, the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150are transferred to the display panel PN (S212). Subsequently, after the plurality of LEDs ED of the donor substrate300is transferred to the display panel PN, the donor substrate300and the display panel PN are detached (S213) and the donor substrate300and the display panel PN are discharged from the process equipment (S214).

Therefore, through the primary transfer process of transferring the plurality of LEDs ED to the donor substrate300from the wafer200and the secondarily transfer process of transferring the plurality of LEDs ED, which has been transferred to the donor substrate300, to the display panel PN, the manufacturing process of the display device100may be completed.

Meanwhile, in the method of manufacturing the display device100according to an exemplary embodiment of the present disclosure, the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150may have the first interval IN1when transferred to one donor substrate300in order to transfer the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150to the display panel PN at once. In this case, as described above, the plurality of protrusions331may have a larger size than the plurality of LEDs ED in consideration of an alignment error between the wafer200and the donor substrate300. When the first wafer210and the donor substrate300are aligned, the plurality of first LEDs130transferred to the plurality of protrusions331may be disposed to deviate from the centers of the upper surfaces of the plurality of protrusions331due to an alignment error between the first alignment key AK1and the first alignment protrusion333. In this case, even if the second wafer220and the donor substrate300are aligned again based on the first alignment key AK1of the second wafer220and the first alignment protrusion333of the donor substrate300and the plurality of second LEDs140transferred to the plurality of protrusions331is disposed at their correct positions, an interval between the plurality of first LEDs130and the plurality of second LEDs140may be different from the first interval IN1and alignment accuracy may decrease.

Accordingly, when the second wafer220and the donor substrate300are aligned, they are aligned based on the second alignment key AK2disposed at a predetermined interval from the first LED130. Thus, the plurality of second LEDs140may be transferred while maintaining the relative position between the plurality of first LEDs130and the plurality of second LEDs140transferred onto the donor substrate300, i.e., the first interval IN1between the plurality of first LEDs130and the plurality of second LEDs140, and alignment accuracy may be improved.

Meanwhile, it has been illustrated inFIG.4throughFIG.7that the donor substrate300is aligned with the second wafer220and the third wafer230and the donor substrate300is aligned with the display panel PN based on the second alignment key AK2transferred to the donor substrate300together with the plurality of first LEDs130to be disposed in the outermost first sub-pixels among the plurality of sub-pixels. However, the present disclosure is not limited thereto. The plurality of second LEDs140and the second alignment key AK2of the second wafer220to be disposed in the central second sub-pixels among the plurality of sub-pixels may be first transferred to the donor substrate300. Thereafter, the donor substrate300may be aligned with the first wafer210and the third wafer230and then aligned with the display panel PN based on the second alignment key AK2from the second wafer220. Alternatively, the plurality of third LEDs150and the second alignment key AK2of the third wafer230to be disposed in the third sub-pixels may be first transferred to the donor substrate300. Thereafter, the donor substrate300may be aligned with the first wafer210and the second wafer220and then aligned with the display panel PN based on the second alignment key AK2from the third wafer230. Therefore, according to the present disclosure, the order of primary transfer processes for the first wafer210, the second wafer220, and the third wafer230is not limited thereto as long as the remaining wafer200and the donor substrate300are aligned based on the plurality of LEDs ED and the second alignment key AK2which are first transferred to the donor substrate300.

Hereinafter, an effect of improving the alignment accuracy of the plurality of LEDs ED in the method of manufacturing the display device100according to an exemplary embodiment of the present disclosure will be described in more detail with reference toFIG.8throughFIG.11.

FIG.8andFIG.9are diagrams for explaining an alignment error range in methods of manufacturing a display device according to comparative embodiments.FIG.10andFIG.11are diagrams for explaining an alignment error range in methods of manufacturing a display device according to exemplary embodiments. Specifically,FIG.8throughFIG.11are diagrams illustrating ideal correct positions of a plurality of LEDs and dispersion caused by alignment errors during primary and secondary transfer processes.FIG.8is a diagram for explaining an alignment error range in a method of manufacturing a display device according to Comparative embodiment 1, andFIG.9is a diagram for explaining an alignment error range in a method of manufacturing a display device according to Comparative embodiment 2.FIG.10is a diagram for explaining an alignment error range in a method of manufacturing a display device according to Exemplary embodiment 1, andFIG.11is a diagram for explaining the alignment error range in a method of manufacturing a display device according to Exemplary embodiment 2.

Meanwhile, alignment error ranges X, 2X, and 3X shown inFIG.8throughFIG.11may be defined as the diameters of the maximum areas up to which a plurality of LEDs and a second alignment key may be transferred while deviating from their correct positions due to an alignment error. The diameters of circles centered at correct position points B, B′, and B″ shown inFIG.8throughFIG.11are illustrated corresponding to the alignment error range X that may be basically occurred during a secondary transfer process.

The method of Comparative embodiment 1 is different from the method of manufacturing the display device100according to an exemplary embodiment of the present disclosure in that during a primary transfer process, a first alignment key of a first wafer is aligned with a first alignment protrusion of a donor substrate to transfer a plurality of first LEDs30, a first alignment key of a second wafer is aligned with the first alignment protrusion of the donor substrate to transfer a plurality of second LEDs40, and a first alignment key of a third wafer is aligned with the first alignment protrusion of the donor substrate to transfer a plurality of third LEDs50. The method of Comparative embodiment 2 is substantially identical to the method of manufacturing the display device100according to an exemplary embodiment of the present disclosure except that during a secondary transfer process, a donor substrate and a display panel are aligned based on a second alignment key transferred together with a second LED40′. The method of Exemplary embodiment 1 is substantially identical to the method of manufacturing the display device100according to an exemplary embodiment of the present disclosure in that primary and secondary transfer processes are performed based on the first LED130of the outermost sub-pixel, e.g., a first sub-pixel, among the plurality of LEDs. In Exemplary embodiment 2 compared to the method of manufacturing the display device100according to an exemplary embodiment of the present disclosure, primary and secondary transfer processes are performed based on a second LED140′ of a central sub-pixel, e.g., the second sub-pixel, among the plurality of LEDs and a second alignment key transferred together with the second LED140′. Hereinafter, for convenience of description, it is assumed that an error range of alignment between a donor substrate and a wafer during a primary transfer process is X and an error range of alignment between the donor substrate and a display panel during a second transfer process is also X.

Referring toFIG.8, it can be assumed that during a primary transfer process of transferring a plurality of LEDs to the donor substrate from the wafer, ideal correct positions of the plurality of LEDs transferred onto the donor substrate are a point A, a point A′, and a point A″, respectively. Specifically, the point A is the correct position of a first LED30on the donor substrate, the point A′ is the correct position of a second LED40on the donor substrate, and the point A″ is the correct position of a third LED50on the donor substrate.

In the method of manufacturing a display device according to Comparative embodiment 1, a primary transfer process is performed by aligning a first alignment key of each of a plurality of wafers with a first alignment protrusion of a donor substrate, and a secondary transfer process is performed by aligning a display panel and the donor substrate based on a second alignment key transferred from a first wafer among a plurality of second alignment keys on the donor substrate.

In the manufacturing method of a display device according to Comparative embodiment 1, during the primary transfer process, the plurality of first LEDs30and the second alignment key of the first wafer may be transferred to the donor substrate. In this case, the first wafer and the donor substrate may be aligned based on a first alignment key of the first wafer and a first alignment protrusion of the donor substrate and dispersion may occur due to an alignment error. For example, when the plurality of first LEDs30and the second alignment key are transferred to the donor substrate from the first wafer, dispersion centered at the correct position point A may occur within the alignment error range X.

Specifically, a resin layer, a plurality of protrusions, and a plurality of alignment protrusions of the donor substrate may be made of a material having viscoelasticity, and when the donor substrate is bonded to a wafer, a pressure may be applied to the donor substrate, which may cause deformation of the resin layer, the plurality of protrusions, and the plurality of alignment protrusions. Accordingly, even if the plurality of LEDs and the second alignment key are transferred to their correct positions, the donor substrate may be partially deformed and each of the plurality of transferred LEDs and second alignment key may deviate from their correct positions. Further, an alignment error between the wafer and the donor substrate may also be caused by a process error, and, thus, dispersion of the plurality of LEDs and the second alignment key may occur. In this case, the maximum range up to which deviation from the correct positions can occur may be the alignment error range X. That is, the second alignment key and the plurality of LEDs may be scattered within the dispersion. For example, the second alignment key may deviate most from its correct position within the alignment error range X and may be disposed on the outermost side within the dispersion, and the other plurality of LEDs may be variously disposed within the dispersion. That is, due to a process error, each of the plurality of first LEDs30and a plurality of second alignment keys may be scattered within the alignment error range X region and within the dispersion.

After the primary transfer of the plurality of first LEDs30and the second alignment key, the plurality of second LEDs40and the second alignment key of the second wafer may be transferred to the donor substrate. In this case, the second wafer and the donor substrate may be aligned based on the first alignment key of the second wafer and the first alignment protrusion of the donor substrate. Further, when the plurality of second LEDs40and the second alignment key are transferred to the donor substrate from the second wafer, dispersion centered at the correct position point A′ may occur within the alignment error range X.

Finally, the plurality of third LEDs50and the second alignment key of the third wafer may be transferred to the donor substrate. In this case, the third wafer and the donor substrate may be aligned based on the first alignment key of the third wafer and the first alignment protrusion of the donor substrate. Further, when the plurality of third LEDs50and the second alignment key are transferred to the donor substrate from the third wafer, dispersion centered at the correct position point A″ may occur within the alignment error range X.

It can be assumed that during a secondary transfer process of transferring the plurality of LEDs to a display panel from the donor substrate, ideal correct positions of the plurality of LEDs transferred onto the display panel are a point B, a point B′, and a point B″, respectively. Specifically, the point B is the correct position of the first LED30and the second alignment key on the display panel, the point B′ is the correct position of the second LED40and the second alignment key on the display panel, and the point B″ is the correct position of the third LED50and the second alignment key on the display panel. The correct position point B′ of the plurality of second LEDs40and the correct position point B″ of the plurality of third LEDs50are ideal correct positions having the first interval IN1which is an interval of the plurality of first LEDs30, the plurality of second LEDs40, and the plurality of third LED50from the plurality of sub-pixels.

Then, the plurality of LEDs and the second alignment key of the donor substrate may be transferred to the display panel. During the secondary transfer process, the plurality of first LEDs30, the plurality of second LEDs40, and the plurality of third LEDs50may be transferred to be located at the correct position points B, B′ and B″ on the display panel.

During the secondary transfer process, the donor substrate and the display panel may be aligned based on the second alignment key to transfer the plurality of first LEDs30, the plurality of second LEDs40, and the plurality of third LEDs50of the donor substrate to the display panel. In this case, the dispersion positions of the plurality of first LEDs30and the second alignment key may vary depending on the position of the second alignment key within the dispersion according to the alignment error range X. For example, when the second alignment key at the center within the dispersion is disposed at the correct position point B, the plurality of first LEDs30and the second alignment key may show the same dispersion centered at the correct position point B as in the primary transfer process.

However, the second alignment key may deviate from the correct position point B due to an alignment error. For example, the second alignment key may be disposed on the rightmost side within the dispersion of the plurality of first LEDs30and the second alignment key, and the plurality of first LEDs30may be distributed between the leftmost side and the rightmost side within the dispersion. In this case, during the secondary transfer process based on the second alignment key on the rightmost side within the dispersion, the second alignment key may be biased toward a point {circle around (1)} on the left side of the correct position point B due to a process error. Thus, the resultant dispersion of the plurality of first LEDs30and the second alignment key may be shifted to the outside of the point {circle around (1)}. In other words, when the second alignment key is disposed on the rightmost side within the dispersion of the plurality of first LEDs30and the second alignment key and the second alignment key is biased toward the point {circle around (1)} on the left side of the correct position point B during the secondary transfer process based on the second alignment key, the dispersion of the plurality of first LEDs30and the second alignment key may be shifted to the outside of the point {circle around (1)}. For another example, the second alignment key may be disposed on the leftmost side within the dispersion of the plurality of first LEDs30and the second alignment key, and the plurality of first LEDs30may be distributed between the rightmost side and the leftmost side within the dispersion. In this case, during the secondary transfer process based on the second alignment key on the leftmost side within the dispersion, the second alignment key may be biased toward a point {circle around (2)} on the right side of the correct position point B due to a process error. Thus, the resultant dispersion of the plurality of first LEDs30and the second alignment key may be shifted to the outside of the point {circle around (2)}.

Further, the display panel and the donor substrate are aligned based on the second alignment key transferred from the first wafer during the secondary transfer process, and, thus, the plurality of second LEDs40and the plurality of third LEDs50disposed on the donor substrate may show the same dispersion as the dispersion of the plurality of first LEDs30and the second alignment key. Specifically, the plurality of second LEDs40and the plurality of third LEDs50disposed on the donor substrate are transferred to the display panel based on the second alignment key from the first wafer. That is, the plurality of second LEDs40and the plurality of third LEDs50disposed on the donor substrate may be transferred to the display panel while maintaining a relative position with respect to the plurality of first LEDs30and the second alignment key. Accordingly, when the second alignment key from the first wafer deviates from the correct position point B, the dispersion of the plurality of second LEDs40and the plurality of third LEDs50may also be shifted in the same manner as the second alignment key and thus may deviate from their correct position points B′ and B″, respectively. Therefore, a basic error range of alignment between the display panel and the donor substrate is X, but an alignment error during the primary transfer process is added, and, thus, error ranges of alignment of the plurality of first LEDs30, the plurality of second LEDs40, and the plurality of third LEDs50, respectively, during the secondary transfer process may be up to 3X.

Thereafter, referring toFIG.9, in the method of manufacturing a display device according to Comparative embodiment 2, a plurality of first LEDs30′, a plurality of second LEDs40′, and a plurality of third LEDs50′ are transferred to one donor substrate, and the plurality of first LEDs30′, the plurality of second LEDs40′, and the plurality of third LEDs50′ of the donor substrate are transferred to a display panel at once. In this case, during a primary transfer process, the plurality of second LEDs40′ of the second wafer and the third LED50′ of the third wafer are transferred to the donor substrate based on a second alignment key transferred together with the plurality of first LEDs30′ and in a secondary transfer process, the plurality of LEDs of the donor substrate is transferred to the display panel based on a second alignment key transferred together with the plurality of second LEDs40′. That is, during the primary transfer process, the second alignment key transferred together with the first LED30′ may serve as a reference for alignment and during the secondary transfer process, the second alignment key transferred together with the second LED40′ may serve as a reference for alignment.

The plurality of first LEDs30′ and the second alignment key of the first wafer are transferred to the donor substrate. Then, after the second wafer and the third wafer are aligned with the donor substrate based on the second alignment key disposed on the donor substrate, the plurality of second LEDs40′ and the plurality of third LEDs50′ are transferred to the donor substrate. In this case, the second alignment key itself disposed at a predetermined interval from the plurality of first LEDs30′ serves as a reference for alignment between the second and third wafers and the donor substrate, and, thus, an alignment error range and dispersion of the plurality of first LEDs30′ may be ignored. Specifically, even if the plurality of first LEDs30′ deviates from the correct position point A on upper surfaces of the plurality of protrusions of the donor substrate due to an alignment error between the first wafer and the donor substrate, the plurality of second LEDs40′ and the plurality of third LEDs50′ to be transferred thereafter are transferred by aligning their relative position with respect to the second alignment key and the plurality of first LEDs30′. Thus, the plurality of second LEDs40′ and the plurality of third LEDs50′ may also deviate from the correct position points A′ and A″ on the upper surfaces of the plurality of protrusions of the donor substrate in the same manner as the plurality of first LEDs30′. Also, each of the plurality of first LEDs30′, the plurality of second LEDs40′, and the plurality of third LEDs50′ may be disposed at a first interval on the donor substrate. Accordingly, the plurality of first LEDs30′ and the second alignment key disposed at a predetermined interval from the plurality of first LEDs30′ serve as a reference for alignment between the second and third wafers and the donor substrate, and, thus, the alignment error range and dispersion of the plurality of first LEDs30′ may be eliminated.

Meanwhile, the plurality of second LEDs40′ transferred to the donor substrate based on the plurality of first LEDs30′ and the second alignment key disposed on the donor substrate may show dispersion centered at the correct position point A′ within the alignment error range X. Likewise, the plurality of third LEDs50′ transferred to the donor substrate based on the plurality of first LEDs30′ and the second alignment key disposed on the donor substrate may show dispersion centered at the correct position point A″ within the alignment error range X.

Then, during the secondary transfer process of transferring the plurality of LEDs to the display panel from the donor substrate, the donor substrate and the display panel may be aligned based on the plurality of second LEDs40′ and the second alignment key transferred together with the plurality of second LEDs40′ and then, the plurality of LEDs of the donor substrate may be transferred to the display panel. During the secondary transfer process, the plurality of LEDs may be transferred to be located at the correct position points B, B′ and B″ on the display panel.

When the plurality of LEDs of the donor substrate is transferred by aligning the donor substrate and the display panel based on the plurality of second LEDs40′ and the second alignment key from the second wafer, the plurality of second LEDs40′ and the second alignment key may change in position based on the correct position point B′ depending on an alignment error. For example, if the second alignment key is disposed on the rightmost side within the dispersion of the plurality of second LEDs40′ and the second alignment key, and the second alignment key is transferred to be biased toward a point {circle around (1)} on the left side of the correct position point B′, the dispersion of the plurality of second LEDs40′ and the second alignment key may be shifted to the outside of the point {circle around (1)}. For example, if the second alignment key is disposed on the leftmost side within the dispersion of the plurality of second LEDs40′ and the second alignment key, and the second alignment key is transferred to be biased toward a point {circle around (2)} on the right side of the correct position point B′, the dispersion of the plurality of second LEDs40′ and the second alignment key may be shifted to the outside of the point {circle around (2)}. Accordingly, an error range of alignment of the plurality of second LEDs40′ during the secondary transfer process may be up to 3X.

Further, the plurality of first LEDs30′ and the plurality of third LEDs50′ transferred to the display panel based on the second LED40′ from the second wafer and the second alignment key transferred together with the second LED40′ may be transferred onto the display panel while maintaining their relative position with respect to the plurality of second LEDs40′. If the plurality of second LEDs40′ is biased toward one side of the correct position point B′ due to an alignment error during transfer, the plurality of first LEDs30′ and the plurality of third LEDs50′ may also be biased toward one side of the correct position points B and B″, respectively, during transfer. For example, if the plurality of second LEDs40′ and the second alignment key are biased toward a point {circle around (1)} on the left side of the correct position point B′ during transfer, the plurality of first LEDs30′ and the plurality of third LEDs50′ may also be biased to the point {circle around (1)} on the left side of the correct position points B and B″, respectively, during transfer. Accordingly, the plurality of third LEDs50′ may have an alignment error range of 3X with respect to the correct position point B″ of the display panel due to the alignment error range 3X of the plurality of second LEDs40′ during the secondary transfer process. However, as for the plurality of first LEDs30′, during the primary transfer process, the plurality of first LEDs30′ and the second alignment key AK2transferred together with the plurality of first LEDs30′ serve as a reference for alignment and the dispersion of the plurality of first LEDs30′ is eliminated. Therefore, the plurality of first LEDs30′ may have only an alignment error range of 2X during the secondary transfer process.

Referring toFIG.10, the method of manufacturing a display device according to Exemplary embodiment 1 is substantially identical to the method of manufacturing the display device100according to an exemplary embodiment of the present disclosure. First, the plurality of first LEDs130of the first wafer210may be transferred to the donor substrate300. Specifically, the first wafer210and the donor substrate300may be aligned based on the alignment key of the first wafer210and the alignment protrusion332of the donor substrate300in order to transfer the plurality of first LEDs130onto the plurality of protrusions331of the donor substrate300.

Then, the plurality of second LEDs140and the plurality of third LEDs150may be aligned based on the second alignment key AK2transferred to the donor substrate300from the first wafer210together with the plurality of first LEDs130.

In this case, the plurality of second LEDs140of the second wafer220and the plurality of third LEDs150of the third wafer230are transferred to the donor substrate300based on the second alignment key AK2transferred to the donor substrate300together with the plurality of first LEDs130. Therefore, an alignment error range and dispersion of the first LEDs130transferred to the donor substrate300may be ignored. Since the plurality of first LEDs130itself serves as a reference for alignment between the second and third wafers220and230and the donor substrate300, a relative position between the plurality of first LEDs130and the protrusions331of the donor substrate300is not important as long as the plurality of first LEDs130is transferred to the upper surfaces of the protrusions331of the donor substrate300. For example, if the plurality of first LEDs130is disposed to be biased toward one side of the protrusions331of the donor substrate300, the second LEDs140of the second wafer220and the third LEDs150of the third wafer230are aligned and transferred based on the first LEDs130. Therefore, the second LEDs140and the third LEDs150may also be transferred to be biased toward one side of the protrusions331of the donor substrate300. Accordingly, the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150transferred onto the donor substrate300may be disposed at an interval equal to or close to the first interval IN1.

After the second wafer220and the third wafer230are aligned based on the second alignment key AK2transferred onto the donor substrate300together with the first LED130, the plurality of second LEDs140, and the plurality of third LEDs150of the second wafer220may be transferred to the donor substrate300. In this case, when the second wafer220is aligned based on the second alignment key AK2transferred together with the first LED130, dispersion may occur due to an alignment error. For example, the plurality of second LEDs140may have an alignment error range X when transferred to the donor substrate300from the second wafer220, and, thus, dispersion centered at the correct position point A′ may occur. The plurality of third LEDs150may have an alignment error range X when transferred to the donor substrate300from the third wafer230, and, thus, dispersion centered at the correct position point A″ may occur.

After the donor substrate300and the display panel PN are aligned based on the second alignment key AK2transferred to the donor substrate300together with the first LED130, the plurality of LEDs ED on the donor substrate300may be transferred to the display panel PN. During the secondary transfer process, the plurality of LEDs ED may be transferred to be located at the correct position points B. B′ and B″ on the display panel PN.

In this case, when the plurality of first LEDs130is transferred to the correct position point B on the display panel PN, the plurality of second LEDs140and the plurality of third LEDs150may also be disposed at the correct position points B′ and B″. Since the plurality of second LEDs140and the plurality of third LEDs150on the donor substrate300are simultaneously transferred to the display panel PN together with the plurality of first LEDs130, a relative position of the plurality of second LEDs140and the plurality of third LEDs150with respect to the plurality of first LEDs130may be fixed. Further, the plurality of second LEDs140may be transferred to the correct position point B′ on the display panel PN according to the dispersion occurring in the primary transfer process. That is, the plurality of second LEDs140may show the same dispersion centered at the correct position point B′ as in the primary transfer process. Likewise, the plurality of third LEDs150disposed on the display panel PN may show the same dispersion centered at the correct position point B″ as in the primary transfer process.

Meanwhile, during the secondary transfer process, the first LED130may have an alignment error range X, and the first LED130may be disposed to be biased toward one side of the correct position point B on the display panel PN due to an alignment error. For example, if the first LED130is biased toward a point {circle around (1)} on the left side of the correct position point B during transfer, the plurality of second LEDs140disposed on the donor substrate300based on the second alignment key AK2transferred together with the plurality of first LEDs130may also be biased toward a point {circle around (1)} on the left side of the correct position point B′ and transferred to the display panel PN. The plurality of second LEDs140may also show dispersion centered at the point {circle around (1)}. Further, the plurality of third LEDs150disposed on the donor substrate300based on the second alignment key AK2transferred together with the plurality of first LEDs130may also be biased toward a point {circle around (1)} on the left side of the correct position point B″ and transferred to the display panel PN. The plurality of third LEDs150may also show dispersion centered at the point {circle around (1)}.

Likewise, if the first LED130is biased toward a point {circle around (2)} due to an alignment error during transfer, the plurality of second LEDs140disposed on the donor substrate300based on the second alignment key AK2transferred together with the plurality of first LEDs130may also be biased toward a point {circle around (2)} on the right side of the correct position point B′ and transferred to the display panel PN. The plurality of second LEDs140may also show dispersion centered at the point {circle around (2)}. Further, the plurality of third LEDs150disposed on the donor substrate300based on the second alignment key AK2transferred together with the plurality of first LEDs130may also be biased toward a point {circle around (2)} on the right side of the correct position point B″ and transferred to the display panel PN. The plurality of third LEDs150may also show dispersion centered at the point {circle around (2)}.

Accordingly, the plurality of first LEDs130may have an alignment error range X and the resultant dispersion during the secondary transfer process. Further, the plurality of second LEDs140and the plurality of third LEDs150may have an alignment error range of 2X with respect to the correct position points B′ and B″ on the display panel PN due to an alignment error range X during the primary transfer process and the alignment error range X of the plurality of first LEDs130. However, even if the plurality of second LEDs140and the plurality of third LEDs150have the alignment error range 2X, a relative position of the plurality of first LEDs130with respect to the plurality of second LEDs140and the plurality of third LEDs150, i.e., an interval between the plurality of LEDs ED may be equal to or close to the first interval IN1.

Finally, referring toFIG.11, in the method of manufacturing a display device according to Exemplary embodiment 2, a plurality of second LEDs140′ and the second alignment key AK2of a second wafer are first transferred to a donor substrate. Subsequently, a plurality of first LEDs130′ of a first wafer and a plurality of third LEDs150′ of a third wafer may be transferred onto the donor substrate. In this case, the first wafer and the donor substrate may be aligned based on the second alignment key transferred to the donor substrate from the second wafer, and the third wafer and the donor substrate may also be aligned based on the second alignment key transferred to the donor substrate from the second wafer.

Then, after the first wafer aligned with the donor substrate is shifted by a first interval, the plurality of first LEDs130′ may be transferred to one side of the plurality of second LEDs140′, respectively. After the third wafer is shifted by the first interval in a direction opposite to the shifted direction of the first wafer, the plurality of third LEDs150′ may be transferred to the other side of the plurality of second LEDs140′, respectively.

In this case, the plurality of first LEDs130′ of the first wafer and the plurality of third LEDs150′ of the third wafer are transferred to the donor substrate based on the second alignment key transferred together with the plurality of second LEDs140′, and, thus, the alignment error range and dispersion of the plurality of second LEDs140′ transferred to the donor substrate may be eliminated. Specifically, the second alignment key itself disposed at a predetermined interval from the plurality of second LEDs140′ serves as a reference for alignment between the first and third wafers and the donor substrate, and, thus, the alignment error range and dispersion of the plurality of second LEDs140′ may be ignored. Specifically, even if the plurality of second LEDs140′ deviates from the correct position point A′ on upper surfaces of a plurality of protrusions of the donor substrate due to an alignment error between the second wafer and the donor substrate, the plurality of first LEDs130′ and the plurality of third LEDs150′ to be transferred thereafter are transferred by aligning their relative position with respect to the second alignment key and the plurality of second LEDs140′. Thus, the plurality of first LEDs130′ and the plurality of third LEDs150′ may also deviate to be disposed from the correct position points A and A″ on the upper surfaces of the plurality of protrusions of the donor substrate in the same manner as the plurality of second LEDs140′. Also, the plurality of first LEDs130′, the plurality of second LEDs140′, and the plurality of third LEDs150′ may be disposed at a first interval on the donor substrate, respectively. Accordingly, the plurality of second LEDs140′ and the second alignment key disposed at a predetermined interval from the plurality of second LEDs140′ serve as a reference for alignment between the first and third wafers and the donor substrate, and, thus, the alignment error range and dispersion of the plurality of second LEDs140′ may be eliminated.

After the first wafer and the third wafer are aligned based on the second alignment key transferred onto the donor substrate together with the plurality of second LEDs140′, the plurality of first LEDs130′ and the plurality of third LEDs150′ may be transferred to the donor substrate. In this case, when the first wafer is aligned based on the second alignment key transferred together with the plurality of second LEDs140′, dispersion may occur due to an alignment error. For example, the plurality of first LEDs130′ may have an alignment error range X when transferred to the donor substrate from the first wafer, and, thus, dispersion centered at the correct position point A may occur. The plurality of third LEDs150′ may have an alignment error range X when transferred to the donor substrate from the third wafer, and, thus, dispersion centered at the correct position point A″ may occur.

After the donor substrate and the display panel are aligned based on the second alignment key transferred to the donor substrate together with the second LED140′, the plurality of LEDs on the donor substrate may be transferred to the display panel. During the secondary transfer process, the plurality of LEDs may be transferred to be located at the correct position points B, B′ and B″ on the display panel.

In this case, when the plurality of second LEDs140′ and the second alignment key are transferred to the correct position point B′ on the display panel, the plurality of first LEDs130′ and the plurality of third LEDs150′ may also be disposed at the correct position points B and B″. Since the plurality of first LEDs130′ and the plurality of third LEDs150′ on the donor substrate are simultaneously transferred to the display panel together with the plurality of second LEDs140′, a relative position of the plurality of first LEDs130′ and the plurality of third LEDs150′ with respect to the plurality of second LEDs140′ may be fixed. Further, the plurality of first LEDs130′ may be transferred to the correct position point B on the display panel according to the dispersion occurring in the primary transfer process. That is, the plurality of first LEDs130′ may show the same dispersion centered at the correct position point B as in the primary transfer process. Likewise, the plurality of third LEDs150′ disposed on the display panel may show the same dispersion centered at the correct position point B″ as in the primary transfer process.

Meanwhile, during the secondary transfer process, the second LED140′ may have an alignment error range X. and the second LED140′ may be disposed to be biased toward one side of the correct position point B′ on the display panel due to an alignment error. For example, if the second LED140′ is biased toward a point {circle around (1)} on the left side of the correct position point B′ during transfer, the plurality of first LEDs130′ disposed on the donor substrate based on the second alignment key transferred together with the plurality of second LEDs140′ may also be biased toward a point {circle around (1)} on the left side of the correct position point B and transferred to the display panel. The plurality of first LEDs130′ may also show dispersion centered at the point {circle around (1)}. Further, the plurality of third LEDs150′ disposed on the donor substrate based on the second alignment key transferred together with the plurality of second LEDs140′ may also be biased toward a point {circle around (1)} on the left side of the correct position point B″ and transferred to the display panel. The plurality of third LEDs150′ may also show dispersion centered at the point {circle around (1)}.

Likewise, if the second LED140′ is biased toward a point {circle around (2)} on the right side of the correct position point B′ due to an alignment error during transfer, the plurality of first LEDs130′ disposed on the donor substrate based on the second alignment key transferred together with the plurality of second LEDs140′ may also be biased toward a point {circle around (2)} on the right side of the correct position point B and transferred to the display panel. The plurality of first LEDs130′ may also show dispersion centered at the point {circle around (2)}. Further, the plurality of third LEDs150′ disposed on the donor substrate based on the second alignment key transferred together with the plurality of second LEDs140′ may also be biased toward a point {circle around (2)} on the right side of the correct position point B″ and transferred to the display panel. The plurality of third LEDs150′ may also show dispersion centered at the point {circle around (2)}.

Accordingly, the plurality of second LEDs140′ may have an alignment error range X and the resultant dispersion during the secondary transfer process. Further, the plurality of first LEDs130′ and the plurality of third LEDs150′ may have an alignment error range of 2X with respect to the correct position points B and B″ on the display panel due to an alignment error range X during the primary transfer process and the alignment error range X of the plurality of second LEDs140′. However, even if the plurality of first LEDs130′ and the plurality of third LEDs150′ have the alignment error range 2X, a relative position of the plurality of first LEDs130′ with respect to the plurality of second LEDs140′ and the plurality of third LEDs150′, i.e., an interval between the plurality of LEDs may be equal to or close to the first interval.

In summary, in the method of manufacturing a display device according to Comparative embodiment 1, the first alignment key of each of the plurality of wafers and the first alignment protrusion of the donor substrate may be aligned so that the plurality of LEDs is transferred to the donor substrate, and the display panel and the donor substrate may be aligned based on one of the second alignment keys transferred to the donor substrate so that the plurality of first LEDs30, the plurality of second LEDs40, and the plurality of third LEDs50may be transferred to the display panel. Therefore, due to an alignment error between the wafer and the donor substrate during the primary transfer process and an alignment error between the donor substrate and the display panel during the secondary transfer process, error ranges of alignment of the plurality of first LEDs30, the plurality of second LEDs40and the plurality of third LEDs50, respectively, may be up to 3X. Therefore, since the first alignment key of each of the plurality of wafers and the first alignment key of the donor substrate are aligned, an interval among the plurality of first LEDs30, the plurality of second LEDs40, and the plurality of third LEDs50on the donor substrate may be different from the first interval. Also, even if the plurality of first LEDs30, the plurality of second LEDs40, and the plurality of third LEDs50are transferred to the display panel, the second alignment key from the first wafer as a reference shows dispersion. If the display panel and the donor substrate are aligned based on the second alignment key showing dispersion, the second alignment key and each of the plurality of LEDs are less likely to be transferred to their correct positions due to a process error. Therefore, it is difficult to precisely align the plurality of first LEDs30, the plurality of second LEDs40, and the plurality of third LEDs50.

In the method of manufacturing a display device according to Comparative embodiment 2, during the primary transfer process of the plurality of first LEDs30′, the plurality of second LEDs40′, and the plurality of third LEDs50′, a relative position of the plurality of first LEDs30′ with respect to the plurality of second LEDs40′ and the plurality of third LEDs50is aligned based on the second alignment key transferred together with the plurality of first LEDs30′. Therefore, during the primary transfer process, dispersion of the plurality of first LEDs30′ caused by an alignment error may be reduced compared to Comparative embodiment 1. However, since the donor substrate and the display panel are aligned based on the plurality of second LEDs40′ showing dispersion and the second alignment key transferred together with the plurality of second LEDs40′ during the secondary transfer process, the plurality of second LEDs40′ and the plurality of third LEDs50′ showing dispersion during the primary transfer process may have an alignment error range of up to 3X, and the plurality of first LEDs30′ from which dispersion has been eliminated during the primary transfer process may also have an alignment error range of up to 2X. Therefore, in Comparative embodiment 2 where the reference for alignment during the primary transfer process is different from the reference for alignment during the secondary transfer process, the error range of alignment of the plurality of LEDs is from 2X to 3X. Therefore, it is difficult to transfer each of the plurality of LEDs to its correct position, and alignment accuracy may decrease.

In the method of manufacturing a display device according to Exemplary embodiment 1, during the primary transfer process, a relative position of the plurality of first LEDs130with respect to the plurality of second LEDs140and the plurality of third LEDs150is aligned by using the second alignment key AK2transferred together with the plurality of first LEDs130as a reference member, and, thus, the alignment error range and dispersion of the plurality of first LEDs130during the primary transfer process may be eliminated. Then, even in the secondary transfer process, the donor substrate300and the display panel PN are aligned based on the same second alignment key AK2as in the primary transfer process, and, thus, the plurality of first LEDs130may have only an alignment error range of X and the plurality of second LEDs140and the plurality of third LEDs150transferred based on the plurality of first LEDs130may also have only an alignment error range of up to 2X. Therefore, in Exemplary embodiment 1 where the reference for alignment during the primary transfer process is the same as the reference for alignment during the secondary transfer process, the error range of alignment of the plurality of LEDs is from X to 2X. Therefore, each of the plurality of LEDs is more likely to be transferred to its correct position than in Comparative embodiments 1 and 2. Even if an alignment error is taken into consideration, an interval between the plurality of LEDs ED may also be close to the first interval IN1. Therefore, alignment accuracy may be improved.

The method of manufacturing a display device according to Exemplary embodiment 2 is different from the method of Exemplary embodiment 1 only in that the plurality of second LEDs140′ transferred to the second sub-pixels, which are central sub-pixels, and the second alignment key transferred together with the plurality of second LEDs140′ serve as a reference for alignment. In the method of manufacturing a display device according to Exemplary embodiment 2, during the primary transfer process, the plurality of second LEDs140′ and the second alignment key of the second wafer are first transferred to the donor substrate and a relative position of the plurality of second LEDs140′ with respect to the plurality of first LEDs130′ and the plurality of third LEDs150′ is aligned based on the second alignment key from the second wafer. Since the second alignment key that maintains a predetermined interval from the plurality of second LEDs140′ is used as a reference member during the primary transfer process, the alignment error range and dispersion of the plurality of second LEDs140′ may be eliminated. Then, even in the secondary transfer process, the donor substrate and the display panel are aligned based on the same second alignment key as in the primary transfer process. Thus, the plurality of second LEDs140′ may have only an alignment error range of X and the plurality of first LEDs130′ and the plurality of third LEDs150′ transferred based on the plurality of second LEDs140′ may also have only an alignment error range of up to 2X. Therefore, in Exemplary embodiment 2 where the reference for alignment during the primary transfer process is the same as the reference for alignment during the secondary transfer process, the error range of alignment of the plurality of LEDs is from X to 2X. Therefore, each of the plurality of LEDs is more likely to be transferred to its correct position than in Comparative embodiments 1 and 2. Even if an alignment error is taken into consideration, an interval between the plurality of LEDs may also be close to the first interval. Therefore, alignment accuracy may be improved.

Therefore, in the display device100according to an exemplary embodiment of the present disclosure, based on the second alignment key AK2transferred together with the plurality of LEDs ED during the primary transfer process and maintaining the same interval from the plurality of LEDs ED all the time, a relative position with respect to the other LEDs ED to be transferred to the donor substrate300is aligned. Thus, an alignment error range of the plurality of LEDs ED may be reduced and alignment accuracy may be improved. Specifically, as for the first wafer210aligned with the donor substrate300first, the donor substrate300and the first wafer210are aligned based on the first alignment key AK1of the first wafer210and the first alignment protrusion333of the donor substrate300so that the plurality of first LEDs130and the plurality of second alignment keys AK2are transferred to the upper surfaces of the plurality of protrusions331and the plurality of second alignment protrusions334, respectively. After the plurality of first LEDs130and the plurality of second alignment keys AK2are transferred together to the donor substrate300, the second wafer220and the third wafer230may be aligned with the donor substrate300based on the plurality of second alignment keys AK2. Even in the secondary transfer process, the donor substrate300and the display panel PN may be aligned based on the same second alignment keys AK2. The second alignment key AK2transferred to the donor substrate300together with the plurality of first LEDs130may maintain the same interval from each of the plurality of first LEDs130. Accordingly, when the second wafer220and the third wafer230are aligned with the donor substrate300based on the second alignment key AK2, a relative position may be aligned in order for the plurality of second LEDs140of the second wafer220and the plurality of first LEDs130of the donor substrate300to have the first interval IN1. Also, a relative position may be aligned in order for the plurality of third LEDs150of the third wafer230and the plurality of first LEDs130and the plurality of second LEDs140of the donor substrate300to have the first interval IN1. Accordingly, the alignment error range and dispersion of the plurality of first LEDs130serving as a reference during the primary transfer process may be eliminated. Also, the plurality of second LEDs140and the plurality of third LEDs150with which the relative position of the plurality of first LEDs130is aligned may have only a minimum alignment error range and dispersion. Further, even in the secondary transfer process, the second alignment key AK2, which has been a reference for alignment of the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150, is used as a reference member, and, thus, it is possible to minimize an alignment error range and dispersion of the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150caused by an alignment error. Furthermore, according to Exemplary embodiment 2, in the display device100according to an exemplary embodiment of the present disclosure, based on the second alignment key AK2transferred together with the plurality of LEDs ED, a relative position between the other LEDs ED and an LED ED disposed on the donor substrate300is aligned. Thus, each of the plurality of LEDs ED may be disposed corresponding to an interval between the plurality of sub-pixels, and the alignment accuracy of the plurality of LEDs ED may be improved.

In the method of manufacturing the display device100according to an exemplary embodiment of the present disclosure, a high-resolution display device100may be manufactured by precisely aligning a plurality of micro-sized LEDs ED. As the size of the plurality of LEDs ED decreases, a higher-quality image may be displayed, which may be advantageous for implementing high resolution. However, as the size of the plurality of LEDs ED decreases, it is difficult to align each of the plurality of LEDs ED during the transfer of the plurality of LEDs ED, and alignment accuracy may decrease. However, in the method of manufacturing the display device100according to an exemplary embodiment of the present disclosure, a relative position between the plurality of LEDs ED on the donor substrate300and the plurality of LEDs ED on the wafer200instead of a relative position between the donor substrate300and the wafer200is aligned. Thus, the alignment accuracy of the plurality of LEDs ED transferred onto the donor substrate300may be improved. Accordingly, even if the plurality of LEDs ED has a micro size, the plurality of LEDs ED may be easily aligned and the high-resolution display device100may be easily manufactured.

Conventionally, only LEDs emitting light of the same color are transferred to one donor substrate and then secondarily transferred again to a display panel. In this case, a second alignment key of a wafer is transferred to the donor substrate for alignment between the donor substrate and the display panel. However, it is difficult to transfer the second alignment key with the same mask and laser as the plurality of LEDs. Thus, a separate process for transferring the second alignment key to the donor substrate is performed. For example, a second alignment key of a first wafer is transferred to one donor substrate to align the donor substrate and the display panel, a second alignment key of a second wafer is transferred to another donor substrate to align the donor substrate and the display panel, and a second alignment key of a third wafer is transferred to yet another donor substrate to align the donor substrate and the display panel. Therefore, in order to align each of one donor substrate, another donor substrate and yet another donor substrate with the display panel, a separate process of transferring the second alignment key is needed, and, thus, the transfer process time and cost increase.

However, in the method of manufacturing the display device100according to an exemplary embodiment of the present disclosure, the process time and cost may be reduced by shortening time required for the primary transfer process. First, in the method of manufacturing the display device100according to an exemplary embodiment of the present disclosure, a plurality of LEDs ED from a plurality of wafers200is primarily transferred to one donor substrate300. In this case, a plurality of second alignment keys AK2may be transferred to the donor substrate300from one wafer200to which the primary transfer process is first performed. Then, when a plurality of LEDs ED of the other wafers200is transferred to the donor substrate300during the primary transfer process, there is no need to transfer the second alignment keys AK2since the second alignment keys AK2are already disposed on the donor substrate300. Conventionally, the second alignment keys AK2need to be transferred three times during the primary transfer process. However, according to the present disclosure, the second alignment keys AK2are transferred only once during the primary transfer process so that the donor substrate300and the display panel PN may be easily aligned during the secondary transfer process. Therefore, in the method of manufacturing the display device100according to an exemplary embodiment of the present disclosure, some processes for transferring the plurality of second alignment keys AK2to the donor substrate300are omitted. Thus, the processing time and cost may be reduced.

In the method of manufacturing the display device100according to an exemplary embodiment of the present disclosure, a plurality of first LEDs130, a plurality of second LEDs140, and a plurality of third LEDs150are transferred onto one donor substrate300so as to correspond to a plurality of sub-pixels, respectively. Thus, it is possible to simplify the secondary transfer process. Conventionally, only one type of LEDs emitting light of the same color is primarily transferred to one donor substrate and then secondarily transferred to a display panel. Accordingly, in order to form one pixel including a first LED, a second LED, and a third LED, each of the primary transfer processes and the secondary transfer processes needs to be performed at least three times. However, in the method of manufacturing the display device100according to an exemplary embodiment of the present disclosure, a plurality of first LEDs130, a plurality of second LEDs140, and a plurality of third LEDs150are primarily transferred onto one donor substrate300so as to correspond to a plurality of sub-pixels, respectively, and the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150disposed on the donor substrate300are transferred to the display panel PN at a time. Accordingly, the display device100may be manufactured. Therefore, one pixel PX including the first LED130, the second LED140, and the third LED150may be formed just by performing the primary transfer process three times and the secondary transfer process one time. Therefore, in the method of manufacturing the display device100according to an exemplary embodiment of the present disclosure, productivity and yield may be improved by forming an integrated donor substrate300on which the plurality of LEDs ED is transferred corresponding to the plurality of sub-pixels, respectively.

FIG.12AthroughFIG.12Eare process flowcharts for explaining a method of manufacturing a display device according to another exemplary embodiment of the present disclosure.FIG.13is a process flowchart for explaining the method of manufacturing a display device according to another exemplary embodiment of the present disclosure. Specifically,FIG.12AthroughFIG.12Eare schematic process diagrams for explaining a primary transfer process, andFIG.13is a schematic process diagram for explaining a secondary transfer process. The method of manufacturing a display device shown inFIG.12AthroughFIG.13is substantially the same as the method of manufacturing a display device shown inFIG.1throughFIG.7except that a reference member for aligning the wafer200with the donor substrate300and the donor substrate300with the display panel PN is one of the plurality of LEDs ED. Therefore, a redundant description thereof will be omitted.

Referring toFIG.12AandFIG.12B, after the primary transfer process of the plurality of first LEDs130to the donor substrate300from the first wafer210is completed, the plurality of second LEDs140of the second wafer220is transferred to the donor substrate300.

In a state where the donor substrate300and the second wafer220are disposed such that the plurality of protrusions331of the donor substrate300and the plurality of second LEDs140of the second wafer220face each other, the donor substrate300and the second wafer220may be aligned.

In this case, the donor substrate300and the second wafer220may be aligned based on some of the plurality of first LEDs130transferred to the donor substrate300from the first wafer210and any one of the components of the second wafer220. For example, the second wafer220and the donor substrate300may be aligned based on some of the plurality of first LEDs130transferred to the donor substrate300from the first wafer210and the first alignment key AK1or the second alignment key AK2of the second wafer220, or the second wafer220and the donor substrate300may be aligned based on some of the plurality of first LEDs130transferred to the donor substrate300and some of the plurality of second LEDs140of the second wafer220.

For example, when the second wafer220and the donor substrate300are aligned based on the first LED130of the donor substrate300and the second alignment key AK2of the second wafer220, the second wafer220and the donor substrate300may be aligned such that the center of the first LED130matches the center of the second alignment key AK2. Then, the donor substrate300and the second wafer220may be aligned by shifting the second wafer220or the donor substrate300such that the active region200A of the second wafer220and the transfer area330A of the donor substrate300correspond to each other.

For another example, when the second wafer220and the donor substrate300are aligned based on the first LED130of the donor substrate300and the second LED140of the second wafer220, the second wafer220and the donor substrate300may be aligned such that the center of the first LED130matches the center of the second LED140. In this case, depending on the positions of the first LED130and the second LED140serving as reference members, the donor substrate300and the second wafer220may be aligned by shifting the second wafer220or the donor substrate300such that the active region200A of the second wafer220and the transfer area330A of the donor substrate300correspond to each other, or the process of shifting the second wafer220or the donor substrate300may be omitted.

In this case, the center of the first LED130may be defined as the center of a shape formed by the edges of the first LED130wien the first LED130serving as a reference member is viewed from the top. For example, when the first LED130serving as a reference member is viewed from the top, the edges of the first LED130may form a square shape, and the donor substrate300and the second wafer220may be aligned based on the center of the square shape.

Referring toFIG.12C, after the alignment between the second wafer220and the donor substrate300is completed, the second wafer220may be shifted by the first interval IN1. After the second wafer220is shifted by the first interval IN1, i.e., the interval between the plurality of sub-pixels, the plurality of second LEDs140is transferred to the donor substrate300.

Then, referring toFIG.12DandFIG.12E, after the primary transfer process of the plurality of second LEDs140is completed, the plurality of third LEDs150of the third wafer230is transferred to the donor substrate300.

First, referring toFIG.12D, in a state the donor substrate300and the third wafer230are disposed such that the plurality of protrusions331of the donor substrate300and the plurality of third LEDs150of the third wafer230face each other, the donor substrate300and the third wafer230may be aligned.

In this case, the donor substrate300and the third wafer230may be aligned based on some of the plurality of first LEDs130transferred to the donor substrate300from the first wafer210and any one of the components of the third wafer230. For example, the third wafer230and the donor substrate300may be aligned based on some of the plurality of first LEDs130transferred to the donor substrate300from the first wafer210and the first alignment key AK1or the second alignment key AK2of the third wafer230, and the second wafer220and the donor substrate300may be aligned based on some of the plurality of first LEDs130transferred to the donor substrate300and some of the plurality of second LEDs140of the second wafer220.

Referring toFIG.12E, after the alignment between the third wafer230and the donor substrate300is completed, the third wafer230may be shifted by the second interval IN2. That is, after the third wafer230is shifted by the first interval IN1twice, the plurality of third LEDs150is transferred to the donor substrate300.

In this case, the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150transferred to the donor substrate300may be transferred at the first interval IN1, which is the interval between the plurality of sub-pixels, to the display panel PN at a time. Accordingly, when the plurality of second LEDs140and the plurality of third LEDs150are transferred to the donor substrate300, the second wafer220and the third wafer230may be aligned with the donor substrate300by using some of the plurality of first LEDs130on the donor substrate300as a reference member. Also, a relative position among the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150may be aligned.

Meanwhile, when the plurality of first LEDs130is transferred to the donor substrate300from the first wafer210, the second alignment key AK2may or may not be transferred. Also, when the plurality of LEDs ED is transferred to the display panel PN from the donor substrate300, the second alignment key AK2may or may not be transferred. In the method of manufacturing a display device according to another exemplary embodiment of the present disclosure, when the donor substrate300and the display panel PN are aligned, the first LED130is used as a reference member instead of the second alignment key AK2. Thus, the second alignment key AK2may be selectively transferred.

The plurality of second LEDs140and the plurality of third LEDs150disposed on the donor substrate300are transferred not based on the first alignment protrusions333of the donor substrate300, but based on some of the plurality of first LEDs130transferred to the donor substrate300from the first wafer210. A relative position of the plurality of second LEDs140and the plurality of third LEDs150transferred to the donor substrate300based on the plurality of first LEDs130with respect to the plurality of first LEDs130may be aligned. Accordingly, the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150may be disposed on the donor substrate300so as to correspond to the plurality of sub-pixels. Further, when the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150are transferred to the display panel PN, the donor substrate300and the display panel PN may be aligned based on the plurality of first LEDs130to transfer the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150. In this case, the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150may be transferred corresponding to the plurality of sub-pixels, respectively.

Therefore, in the method of manufacturing a display device according to another exemplary embodiment of the present disclosure, the second wafer220and the third wafer230may be aligned with the donor substrate300based on some of the plurality of first LEDs130first transferred onto the donor substrate300. Thus, the alignment accuracy of the plurality of first LEDs130, the plurality of second LEDs140, and the plurality of third LEDs150may be improved. Specifically, without a separate component to align the wafer200with the donor substrate300and the donor substrate300with the display panel PN, the donor substrate300may be aligned with the wafer200and the display panel PN based on one of the plurality of first LEDs130. Accordingly, the structures of the wafer200, the donor substrate300, and the display panel PN may be simplified, and the transfer process of the second alignment key AK2may be simplified. The second alignment key AK2may have a different shape from the plurality of LEDs ED and may be individually transferred. That is, since the second alignment key AK2has a different shape from the plurality of first LEDs130, a mask or laser used in the transfer process may be different. Also, it is difficult to simultaneously transfer the second alignment key AK2with the plurality of first LEDs130, and the second alignment key AK2may be transferred in a separate process from the plurality of first LEDs130. However, in the method of manufacturing a display device according to another exemplary embodiment of the present disclosure, the plurality of LEDs ED itself is used as a reference member for aligning the wafer200with the donor substrate300and the donor substrate300with the display panel PN. Accordingly, the transfer process of the second alignment key AK2may be simplified, and the structures of the wafer200and the donor substrate300may be simplified.

According to an aspect of the present disclosure, there is provided a method of manufacturing a display device. The method of manufacturing a display device includes a process of aligning a first wafer on which a plurality of first LEDs, a plurality of alignment keys, and a reference member are disposed with a donor substrate, a process of transferring the plurality of first LEDs and the reference member on the first wafer to the donor substrate, and a process of aligning a second wafer on which a plurality of second LEDs is disposed with the donor substrate based on the reference member.

In the process of aligning the first wafer with the donor substrate, the first wafer may be aligned with the donor substrate based on a first alignment key among the plurality of alignment keys of the first wafer and a first alignment protrusion of the donor substrate.

The method of manufacturing a display device may further include a process of transferring the plurality of second LEDs on the second wafer to the donor substrate on which the plurality of first LEDs is disposed, a process of aligning a third wafer on which a plurality of third LEDs is disposed with the donor substrate based on the reference member, and a process of transferring the plurality of third LEDs on the third wafer to the donor substrate on which the plurality of first LEDs and the plurality of second LEDs are disposed.

The method of manufacturing a display device may further include a process of shifting the second wafer aligned with the donor substrate based on the reference member before the process of transferring the plurality of second LEDs to the donor substrate, and a process of shifting the third wafer aligned with the donor substrate based on the reference member before the process of transferring the plurality of third LEDs to the donor substrate.

The plurality of first LEDs, the plurality of second LEDs, and the plurality of third LEDs disposed on the donor substrate may be disposed at a first interval.

The second wafer may be shifted by a first interval and the third wafer may be shifted by a second interval, which is larger than the first interval, in the same direction as the shifted direction of the second wafer, and the plurality of second LEDs may be transferred to one side of the plurality of first LEDs, respectively, and the plurality of third LEDs may be transferred to one side of the plurality of second LEDs, respectively, on the donor substrate.

The second wafer may be shifted by a first interval and the third wafer may be shifted by the first interval in a direction opposite to the shifted direction of the second wafer, and the plurality of second LEDs may be transferred to one side of the plurality of first LEDs, respectively, and the plurality of third LEDs may be transferred to the other side of the plurality of first LEDs, respectively, on the donor substrate.

The method of manufacturing a display device may further include a process of aligning the donor substrate on which the plurality of first LEDs, the plurality of second LEDs, and the plurality of third LEDs are disposed with a display panel based on the reference member, and a process of transferring the plurality of first LEDs, the plurality of second LEDs, and the plurality of third LEDs disposed on the donor substrate to the display panel.

The reference member may be at least one of the plurality of first LEDs transferred onto the donor substrate.

The reference member may be a second alignment key transferred to the donor substrate together with the plurality of first LEDs among the plurality of alignment keys disposed on the first wafer.

In the process of aligning the second wafer with the donor substrate, the second wafer may be aligned with the donor substrate based on at least one of the plurality of second LEDs of the second wafer and the reference member.

In the process of aligning the second wafer with the donor substrate, the second wafer may be aligned with the donor substrate based on at least one of a plurality of alignment keys of the second wafer and the reference member.

According to another aspect of the present disclosure, there is a method of manufacturing a display device. The method of manufacturing a display device includes a process of aligning a first wafer on which a reference member and a plurality of first LEDs are disposed with a donor substrate, a process of transferring the plurality of first LEDs and the reference member of the first wafer to the donor substrate, a process of aligning a second wafer on which a plurality of second LEDs is disposed with the donor substrate based on the reference member transferred onto the donor substrate, a process of transferring the plurality of second LEDs of the second wafer to the donor substrate, a process of aligning a third wafer on which a plurality of third LEDs is disposed with the donor substrate based on the reference member transferred onto the donor substrate, and a process of transferring the plurality of third LEDs of the third wafer to the donor substrate.

The reference member may be one of the plurality of first LEDs.

A plurality of alignment keys disposed on the first wafer together with the plurality of first LEDs may be further included, the plurality of alignment keys may include a first alignment key aligned with an alignment protrusion of the donor substrate and a second alignment key which is the reference member, and the first alignment key may have a different size from the second alignment key.

A first LED disposed at a shortest distance from the second alignment key among the plurality of first LEDs may have a constant interval from the second alignment key.

In the process of transferring the plurality of second LEDs to the donor substrate, the second wafer may be shifted and then the plurality of second LEDs may be transferred, and in the process of transferring the plurality of third LEDs to the donor substrate, the third wafer may be shifted by a different interval or in a different direction from the second wafer and then the plurality of third LEDs may be transferred.

In the process of aligning the second wafer with the donor substrate, a relative position between the plurality of first LEDs disposed on the donor substrate and the plurality of second LEDs disposed on the second wafer may be aligned, and in the process of aligning the third wafer with the donor substrate, a relative position between the plurality of first LEDs and the plurality of second LEDs disposed on the donor substrate and the plurality of third LEDs disposed on the third wafer may be aligned.

The method of manufacturing a display device may further include a process of aligning the donor substrate on which the plurality of first LEDs, the plurality of second LEDs, and the plurality of third LEDs are disposed with a display panel based on the reference member transferred onto the donor substrate, and a process of transferring each of the plurality of first LEDs, the plurality of second LEDs, and the plurality of third LEDs on the donor substrate to the display panel so as to correspond to each of a first sub-pixel, a second sub-pixel, and a third sub-pixel of the display panel.