Transfer substrate

Abstract

The transfer substrate includes a first layer and a second layer on the first layer. The content of the curing agent in the second layer may be less than the content of the curing agent in the first layer. A viscous strength of the second layer may be greater than a viscous strength of the first layer, and a hardness of the second layer may be less than a hardness of the first layer.

Description

Technical Field

[0001] This embodiment relates to a transfer substrate for transferring semiconductor light-emitting elements. Background Art

[0002] Large-area displays include liquid crystal displays (LCDs), OLED displays, and micro-LED displays.

[0003] A micro-LED display is a display that uses micro-LEDs, which are semiconductor light-emitting elements, as display elements, each having a diameter or cross-sectional area of 100 μm or less.

[0004] Since a micro-LED display uses semiconductor light-emitting elements, i.e., micro-LEDs, as display elements, it has excellent performance in many characteristics such as contrast, response speed, color reproducibility, viewing angle, brightness, resolution, lifespan, luminous efficiency, or luminance.

[0005] In particular, a micro-LED display has the advantages of being able to freely adjust the size or resolution by separating and combining the screen in a modular manner, and being able to achieve flexible display.

[0006] However, since a large micro-LED display requires millions or more micro-LEDs, there is a technical problem in that it is difficult to transfer micro-LEDs to a display panel quickly and accurately.

[0007] Recently developed transfer techniques include a pick-and-place process, a laser lift-off method, or a self-assembly method.

[0008] Among them, the pick-and-place process is a method of picking up a plurality of semiconductor light-emitting elements using a transfer substrate and transferring them onto a backplane substrate.

[0009] As Figure 1 shown, a plurality of semiconductor light-emitting elements 5 on a wafer are picked up by a transfer substrate 1 and moved to a backplane substrate 3, and then the plurality of semiconductor light-emitting elements 5 are transferred from the transfer substrate 1 to the backplane substrate 3.

[0010] Since it is difficult to enlarge the transfer substrate 1, the transfer process is repeated dozens to hundreds of times to transfer the semiconductor light-emitting elements 5 onto the display area of the backplane substrate 3.

[0011] In this way, the transfer process is repeated dozens to hundreds of times for each backplane substrate 3, causing the transfer substrate 1 to deform, i.e., stretch. Here, deformation means distortion from a preset reference point. In this case, an alignment error E is generated among the multiple semiconductor light-emitting elements 5 picked up on the transfer substrate 1, which leads to an alignment error. When an alignment error occurs, each of the multiple semiconductor light-emitting elements 5 transferred by the transfer substrate 1 is located in an area outside the desired area (pixel). For example, each of the multiple semiconductor light-emitting elements 5 is located between adjacent pixels rather than in its own pixel.

[0012] Thus, when the electrical connection process is performed through post-processing in a state where an alignment error occurs among the multiple semiconductor light-emitting elements 5, there is a problem that the electrode wiring is not electrically connected to each of the multiple semiconductor light-emitting elements, resulting in a disconnection defect, which leads to a lighting defect.

[0013] Meanwhile, as Figure 2 shown, the transfer substrate 1 is repeatedly transferred multiple times so that the multiple semiconductor light-emitting elements 5 are transferred onto multiple block regions 7 of the backplane substrate 3. The block region 7 refers to an area where multiple semiconductor light-emitting elements 5 are transferred through one transfer process of the transfer substrate 1. That is, when the backplane substrate 3 is divided into 9 block regions 7, the multiple semiconductor light-emitting elements 5 are transferred onto the 9 block regions 7 provided on the backplane substrate 3 through 9 transfer processes. In Figure 2 , for ease of explanation, 9 block regions 7 are shown, but the number of block regions 7 varies according to the size of the backplane substrate 3 or the size of the transfer substrate 1.

[0014] The transfer substrate 1 is pressed to transfer the multiple semiconductor light-emitting elements 5 on the transfer substrate 1 onto the backplane substrate 3. When the transfer substrate 1 is pressed, the stress transfers from the center of the transfer substrate 1 to the edge, and the stress transferred to the edge of the transfer substrate 1 is transferred to the surrounding block regions in contact with the currently transferred block region through the multiple semiconductor light-emitting elements 5. When the backplane substrate 3 has a thin thickness or flexible characteristics, the backplane substrate 3 deforms, warps, or bends due to the stress transferred from the transfer substrate 1. In this case, when the multiple semiconductor light-emitting elements 5 have been transferred between the surrounding block regions, the multiple semiconductor light-emitting elements 5 also warp or bend, which leads to a problem of lighting defects due to electrical disconnection during post-processing. In addition, when the multiple semiconductor light-emitting elements 5 also warp or bend, there is a problem that the already transferred semiconductor light-emitting elements fall off the backplane substrate 3. SUMMARY OF THE INVENTION

[0015] TECHNICAL PROBLEM

[0016] An object of the present embodiment is to solve the above problems and other problems.

[0017] Another object of the present embodiment is to provide a transfer substrate capable of preventing alignment errors.

[0018] Another object of the present embodiment is to provide a transfer substrate capable of improving the yield.

[0019] In addition, another object of the present embodiment is to provide a transfer substrate capable of preventing stress transfer.

[0020] The technical problems of the embodiments are not limited to those described in this item and include those that can be understood through the description of the present invention.

[0021] Technical solution

[0022] According to one aspect of the embodiment, in order to achieve the above or other objects, a transfer substrate is provided, which includes: a first layer; and a second layer on the first layer, wherein the amount of the curing agent in the second layer is less than the amount of the curing agent in the first layer, wherein the viscosity of the second layer is greater than the viscosity of the first layer, and wherein the hardness of the second layer is less than the hardness of the first layer.

[0023] The amount of the curing agent in the first layer may be 11 wt% to 13 wt%, and the amount of the curing agent in the second layer may be 9 wt% to 10 wt%.

[0024] The second layer may include: a plurality of protrusions; and recesses surrounding each of the plurality of protrusions.

[0025] Each of the plurality of protrusions may have a size corresponding to the size of at least one pixel, and the pixel may include a plurality of sub-pixels respectively corresponding to a plurality of semiconductor light-emitting elements.

[0026] The transfer substrate may include: a third layer in the recesses.

[0027] The first layer to the third layer may include the same organic material, and the amount of the curing agent in the third layer may be equal to or less than the amount of the curing agent in the first layer and greater than the amount of the curing agent in the protrusions.

[0028] The viscosity of the third layer may be equal to or greater than the viscosity of the first layer and less than the viscosity of the second layer, wherein the hardness of the third layer may be equal to or less than the hardness of the first layer and greater than the hardness of the second layer.

[0029] The third layer may be an extension extending from the first layer.

[0030] The thickness of the third layer may be less than the thickness of the protrusions.

[0031] The transfer substrate may include a support member under the first layer, and the support member and the first layer may include different organic materials.

[0032] The support member may include a plastic material, and the first layer and the second layer may include a silicon material.

[0033] The transfer substrate may include a fourth layer under the first layer, and the first layer, the second layer, and the fourth layer may include the same organic material, and the amount of the curing agent in the fourth layer may be greater than the amount of the curing agent in the first layer.

[0034] The amount of the curing agent in the fourth layer may be at least twice the amount of the curing agent in the second layer.

[0035] The area of the first layer may be greater than the area of the second layer, and the transfer substrate may include: a second recess along the periphery of the outer side of the second layer in the edge region of the upper surface of the first layer.

[0036] Advantageous effects

[0037] As Figure 8 shown, this embodiment enables the stamper member 213 in the transfer substrate 201 to be divided into the first layer 215 and the second layer 216, and the amount of the curing agent in each of the first layer 215 and the second layer 216 may be different. For example, the amount of the curing agent in the second layer 216 may be less than the amount of the curing agent in the first layer 215. Therefore, the second layer 216 to which the semiconductor light-emitting element is attached can increase the adhesiveness to improve the yield. In addition, the first layer 215 can increase the hardness to prevent the deformation of the transfer substrate 201, so that the alignment accuracy can be increased during the transfer of the semiconductor light-emitting element.

[0038] As Figure 14 shown, this embodiment enables the second layer 216 to include a plurality of protrusions 216a, and the plurality of protrusions 216a may have dimensions corresponding to the dimensions of at least one or more pixels defined on the backplane substrate 300, so that the transfer process can be fast and the transfer process time can be shortened.

[0039] As Figure 18 shown, this embodiment enables the third layer 217 to be disposed between the plurality of protrusions 216a of the second layer 216, thereby preventing the deformation of each of the plurality of protrusions 216a of the second layer 216.

[0040] As Figure 19 shown, this embodiment enables the third layer 217 to be disposed under the stamper member 213 (i.e., the first layer 215), thereby having Figure 8 , Figure 14 andFigure 18 The function of the support member 211 shown in [reference], so that it is possible to prevent the discard of the transfer substrate 204 due to the second deformation that occurs when the support member 211 and the stamper member 213 are attached using a double-sided tape.

[0041] As Figure 21 shown, the recess 219 may be formed on the first layer 215 along the periphery of the outer side of the second layer 216, so that the stress generated on the transfer substrate 205 during the transfer process can be absorbed by the recess 219. Therefore, the semiconductor light-emitting elements transferred to the peripheral block regions 310 adjacent to the specific block region 310 where the transfer substrate 205 is pressed may not fall off due to stress. In addition, it is possible to prevent the semiconductor light-emitting elements transferred to the peripheral block regions 310 from warping or bending, so that it is possible to prevent poor lighting caused by electrical disconnection during post-processing.

[0042] From the following detailed description, the additional scope of application of the present embodiment will become apparent. However, since various changes and modifications within the spirit and scope of the embodiment can be clearly understood by those skilled in the art, the detailed description and specific embodiments (for example, preferred embodiments) should be understood as being given only by way of example. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Shows the alignment error of the semiconductor light-emitting elements that occurs during the transfer of the transfer substrate.

[0044] Figure 2 Shows the propagation progress of the stress generated in the transfer substrate.

[0045] Figure 3 Shows the living room of a house equipped with a display device according to an embodiment.

[0046] Figure 4 Is a block diagram schematically showing a display device according to an embodiment.

[0047] Figure 5 Shows Figure 4 An example circuit diagram of the pixel of [[reference]].

[0048] Figure 6 Is Figure 3 An enlarged view of the first panel area in the display device of [[reference]].

[0049] Figure 7 Is a cross-sectional view showing a manufacturing method of a display device according to an embodiment.

[0050] Figure 8 Is a graph showing the relationship between the Young's modulus and the viscosity of an organic material.

[0051] Figure 9 It is a graph showing the amount of change of each of the high-viscosity material and the low-viscosity material according to the number of repeated evaluations.

[0052] Figure 10 It is a graph showing the yield according to the hardness.

[0053] Figure 11 It is a cross-sectional view showing the transfer substrate according to the first embodiment.

[0054] Figure 12 It is a flowchart showing the manufacturing method of the transfer substrate according to the first embodiment.

[0055] Figure 13 It is a top view showing the transfer substrate according to the second embodiment.

[0056] Figure 14 It is a cross-sectional view showing the transfer substrate according to the second embodiment.

[0057] Figure 15 Shows the Figure 14 transfer substrate positioned on the backplane substrate.

[0058] Figure 16 Shows a plurality of semiconductor light-emitting elements picked up on the protrusions corresponding to one pixel size.

[0059] Figure 17 It is a cross-sectional view showing the manufacturing method of the transfer substrate according to the second embodiment.

[0060] Figure 18 It is a cross-sectional view showing the transfer substrate according to the third embodiment.

[0061] Figure 19 It is a cross-sectional view showing the transfer substrate according to the fourth embodiment.

[0062] Figure 20 It is a top view showing the transfer substrate according to the fifth embodiment.

[0063] Figure 21 It is a cross-sectional view showing the transfer substrate according to the fifth embodiment.

[0064] Figure 22 Shows the propagation progress of the stress generated in the transfer substrate according to the fifth embodiment.

[0065] The sizes, shapes, dimensions, etc. of the elements shown in the drawings may be different from the actual ones. In addition, even if the same elements are shown with different sizes, shapes, dimensions, etc. between the drawings, this is only an example on the drawings, and the same elements have the same size, form, dimension, etc. between the drawings. Detailed Description

[0066] In the following, embodiments disclosed in this specification will be described in detail with reference to the accompanying drawings. However, regardless of the reference numerals, the same or similar elements are given the same reference numerals, and redundant descriptions thereof will be omitted. For the convenience of writing this specification, the suffixes "module" and "unit" for the elements used in the following description may be used interchangeably, and they do not have different meanings or functions from each other. In addition, the accompanying drawings are for facilitating the understanding of the embodiments disclosed in this specification, and the technical idea disclosed in this specification is not limited by the accompanying drawings. Further, when an element (e.g., a layer, a region, or a substrate) is referred to as being "on" another element, this means that it can be directly on the other element, or there may be other intermediate elements therebetween.

[0067] The display device described in this specification may include a TV, a signage, a mobile terminal such as a mobile phone or a smartphone, a computer monitor such as a laptop or a desktop computer, a head-up display (HUD) for a vehicle, a backlight unit for a display, a display for augmented reality (XR) (such as AR, VR, and mixed reality (MR)), a light source, etc. However, the configuration according to the embodiments described in this specification can equally be applied to a device capable of displaying, even if it is a new product type developed in the future.

[0068] Figure 3 A living room of a house provided with a display device according to an embodiment is shown.

[0069] Referring to Figure 3 , the display device 100 of this embodiment can display the states of various electronic products such as a washing machine 101, a robotic vacuum cleaner 102, and an air purifier 103, can communicate with each electronic product based on IoT, and can control each electronic product based on user-set data.

[0070] The display device 100 according to an embodiment may include a flexible display manufactured on a thin and flexible substrate. The flexible display can be bent or curled like paper while maintaining the characteristics of a conventional flat panel display.

[0071] In the flexible display, visual information can be realized by independently controlling the light emission of unit pixels arranged in a matrix form. A unit pixel refers to the smallest unit for realizing one color. The unit pixels of the flexible display can be realized by light-emitting elements. In an embodiment, the light-emitting element may be a micro LED or a nano LED, but is not limited thereto.

[0072] Figure 4 is a block diagram schematically showing a display device according to an embodiment, and Figure 5 is showing Figure 3Circuit diagram of an example of pixels.

[0073] Referring to Figure 4 and Figure 5 According to an embodiment, the display device may include a display panel 10, a driving circuit 20, a scan driving unit 30, and a power supply circuit 50.

[0074] The display device 100 of the present embodiment may drive the light-emitting elements in an active matrix (AM) mode or a passive matrix (PM) mode.

[0075] The driving circuit 20 may include a data driving unit 21 and a timing control unit 22.

[0076] The display panel 10 may be formed in a rectangular shape, but is not limited thereto. That is, the display panel 10 may be formed in a circular or elliptical shape. At least one side of the display panel 10 may be formed to be curved with a predetermined curvature.

[0077] The display panel may include a display area DA. The display area DA is an area where pixels PX are formed to display an image. The display panel may include a non-display area NDA. The non-display area NDA may be an area other than the display area DA.

[0078] As an example, the display area DA and the non-display area NDA may be defined on the same surface. For example, the non-display area NDA may surround the display area DA on the same surface as the display area DA, but is not limited thereto.

[0079] As another example, although not shown in the figure, the display area DA and the non-display area NDA may be defined on different surfaces. For example, the display area DA may be defined on the upper surface of the substrate, and the non-display area NDA may be defined on the lower surface of the substrate. For example, the non-display area NDA may be defined on the entire area or a part of the lower surface of the substrate.

[0080] Meanwhile, although the drawings show that the display area DA and the non-display area NDA are divided, the display area DA and the non-display area NDA may not be divided. In other words, only the display area DA may exist on the upper surface of the substrate, and the non-display area NDA may not exist. In other words, the entire area of the upper surface of the substrate may be the display area DA where the image is displayed, and there may be no border area as the non-display area NDA.

[0081] The display panel 10 may include data lines (D1 to Dm, where m is an integer greater than or equal to 2), scan lines (S1 to Sn, where n is an integer greater than or equal to 2) intersecting the data lines D1 to Dm, a high-potential voltage line VDDL supplied with a high-potential voltage VDD, a low-potential voltage line VSSL supplied with a low-potential voltage VSS, and pixels PX connected to the data lines D1 to Dm and the scan lines S1 to Sn.

[0082] Each of the pixels PX may include a first sub-pixel PX1, a second sub-pixel PX2, and a third sub-pixel PX3. The first sub-pixel PX1 may emit first-color light having a first main wavelength, the second sub-pixel PX2 may emit second-color light having a second main wavelength, and the third sub-pixel PX3 may emit third-color light having a third main wavelength. The first-color light may be red light, the second-color light may be green light, and the third-color light may be blue light, but the present invention is not limited thereto. In addition, although Figure 3 it is shown that each of the pixels PX includes three sub-pixels, the present invention is not limited thereto. That is, each of the pixels PX may include four or more sub-pixels.

[0083] Each of the first sub-pixel PX1, the second sub-pixel PX2, and the third sub-pixel PX3 may be connected to at least one of the data lines D1 to Dm, at least one of the scan lines S1 to Sn, and the high-potential voltage line VDDL. As Figure 5 shown, the first sub-pixel PX1 may include a light-emitting element LD, a plurality of transistors for supplying current to the light-emitting element LD, and at least one capacitor Cst.

[0084] Although not shown in the figure, each of the first sub-pixel PX1, the second sub-pixel PX2, and the third sub-pixel PX3 may include only one light-emitting element LD and at least one capacitor Cst.

[0085] Each of the light-emitting elements LD may be a semiconductor light-emitting diode including a first electrode, a plurality of conductive semiconductor layers, and a second electrode. Here, the first electrode may be an anode electrode, and the second electrode may be a cathode electrode, but it is not limited thereto.

[0086] The light-emitting element LD may be one of a lateral-type light-emitting element, a flip-chip type light-emitting element, and a vertical-type light-emitting element.

[0087] As Figure 5As shown, multiple transistors may include a driving transistor DT for supplying current to a light-emitting element LD and a scanning transistor ST for supplying a data voltage to a gate electrode of the driving transistor DT. The driving transistor DT may include a gate electrode connected to a source electrode of the scanning transistor ST, a source electrode connected to a high-potential voltage line VDDL to which a high-potential voltage VDD is applied, and a drain electrode connected to a first electrode of the light-emitting element LD. The scanning transistor ST may include a gate electrode connected to a scanning line (Sk, where k is an integer satisfying 1 ≤ k ≤ n), a source electrode connected to a gate electrode of the driving transistor DT, and a drain electrode connected to a data line (Dj, where j is an integer satisfying 1 ≤ j ≤ m).

[0088] A capacitor Cst is formed between the gate electrode and the source electrode of the driving transistor DT. The storage capacitor Cst charges the difference between the gate voltage and the source voltage of the driving transistor DT.

[0089] The driving transistor DT and the scanning transistor ST may be formed of thin-film transistors. In addition, in Figure 5 it is mainly described that the driving transistor DT and the scanning transistor ST are formed as P-type metal-oxide semiconductor field-effect transistors (MOSFETs), but the present invention is not limited thereto. The driving transistor DT and the scanning transistor ST may also be formed as N-type MOSFETs. In this case, the positions of the source electrode and the drain electrode of each of the driving transistor DT and the scanning transistor ST may be changed.

[0090] In addition, in Figure 5 it is shown that the first sub-pixel PX1, the second sub-pixel PX2, and the third sub-pixel PX3 include a 2T1C (2 transistors - 1 capacitor) having one driving transistor DT, one scanning transistor ST, and one capacitor Cst, but the present invention is not limited thereto. The first sub-pixel PX1, the second sub-pixel PX2, and the third sub-pixel PX3 may each include multiple scanning transistors ST and multiple capacitors Cst.

[0091] Since the second sub-pixel PX2 and the third sub-pixel PX3 may be represented by substantially the same circuit diagram as the first sub-pixel PX1, a detailed description thereof will be omitted.

[0092] The driving circuit 20 outputs signals and voltages for driving the display panel 10. To this end, the driving circuit 20 may include a data driving unit 21 and a timing control unit 22.

[0093] The data driving unit 21 receives digital video data DATA and a source control signal DCS from the timing control unit 22. The data driving unit 21 converts the digital video data DATA into an analog data voltage according to the source control signal DCS, and supplies the converted data to the data lines D1 to Dm of the display panel 10.

[0094] The timing control unit 22 receives digital video data DATA and a timing signal from a host system. The host system may be an application processor of a smart phone or a tablet PC, a monitor, a system-on-chip of a TV, etc.

[0095] The timing control unit 22 generates control signals for controlling the operation timing of the data driving unit 21 and the scan driving unit 30. The control signals may include a source control signal DCS for controlling the operation timing of the data driving unit 21 and a scan control signal SCS for controlling the operation timing of the scan driving unit 30.

[0096] The driving circuit 20 may be disposed in a non-display area NDA arranged on one side of the display panel 10. The driving circuit 20 may be formed as an integrated circuit (IC) and mounted on the display panel 10 using a chip-on-glass (COG) method, a chip-on-plastic (COP) method, or an ultrasonic bonding method, but the present invention is not limited thereto. For example, the driving circuit 20 may be mounted on a circuit board (not shown) other than the display panel 10.

[0097] The data driving unit 21 may be mounted on the display panel 10 using a chip-on-glass (COG) method, a chip-on-plastic (COP) method, or an ultrasonic bonding method, and the timing control unit 22 may be mounted on a circuit board.

[0098] The scan driving unit 30 receives a scan control signal SCS from the timing control unit 22. The scan driving unit 30 generates scan signals according to the scan control signal SCS and supplies them to the scan lines S1 to Sn of the display panel 10. The scan driving unit 30 may be formed in the non-display area NDA of the display panel 10 and include a plurality of transistors. Alternatively, the scan driving unit 30 may be formed as an integrated circuit, in which case it may be mounted on a gate flexible film attached to the other side of the display panel 10.

[0099] The power supply circuit 50 may generate voltages required to drive the display panel 10 from a main power supply applied from a system board and supply them to the display panel 10. For example, the power supply circuit 50 may generate a high-potential voltage VDD and a low-potential voltage VSS for driving the light-emitting elements LD of the display panel 10 from the main power supply and supply them to the display panel 10. In addition, the power supply circuit 50 may generate and supply a driving voltage for driving the driving circuit 20 and the scan driving unit 30 from the main power supply.

[0100] Figure 6 is Figure 3 an enlarged view of a first panel region in a display device of

[0101] Referring to Figure 6 , the display device 100 of the present embodiment can be manufactured by mechanically and electrically connecting a plurality of panel regions (e.g., the first panel region A1) through tiling.

[0102] The first panel region A1 may include a plurality of semiconductor light-emitting elements 150 provided for each unit pixel (see PX in Figure 4 ).

[0103] Hereinafter, various embodiments for solving the above problems will be described with reference to Figures 7 to 22 . Any description omitted below can be easily understood based on the above description of Figures 3 to 6 and the corresponding drawings.

[0104] In an embodiment, the transfer substrate may be a substrate for transferring a plurality of semiconductor light-emitting elements from a wafer, a temporary substrate, or a donor substrate 400 (hereinafter referred to as the donor substrate) to a backplane substrate 300, a semiconductor substrate, a wiring substrate, or a display substrate (hereinafter referred to as the backplane substrate). One side of the transfer substrate may be mounted on the head of a pick-and-place device (hereinafter referred to as the transfer device), and the other side of the transfer substrate may have adhesiveness. In this case, the transfer substrate can be moved to the donor substrate 400 by the operation of the transfer device to pick up a plurality of semiconductor light-emitting elements on the donor substrate 400, and then moved to the backplane substrate 300 to place the plurality of semiconductor light-emitting elements on the backplane substrate 300. When the display area on the backplane substrate 300 where the semiconductor light-emitting elements are placed is dozens to hundreds of times larger than the area of the transfer substrate, this transfer process can be repeatedly performed dozens to hundreds of times. When no separate reference numerals are given, the semiconductor light-emitting elements described in other drawings except Figure 7 may be the semiconductor light-emitting elements 150 shown in Figure 7 .

[0105] Figure 7 is a cross-sectional view showing a manufacturing method of a display device according to an embodiment.

[0106] As shown in Figure 7As shown in (a) of, a series of semiconductor processes may be performed to provide a plurality of semiconductor light-emitting elements 150 on a donor substrate 400. In an embodiment, the semiconductor light-emitting element 150 may be a vertical semiconductor light-emitting element 150. In the vertical semiconductor light-emitting element 150, electrodes may be formed not only on the upper side of the light-emitting layer but also on the lower side. Therefore, after performing semiconductor processes on the wafer to form the light-emitting layer and the upper electrode, the upper electrode may be bonded to the temporary substrate. Then, after the wafer is separated, a lower electrode may be formed on the lower side of the separated and exposed light-emitting layer. Then, the lower electrode may be bonded to the donor substrate 400 and the temporary substrate may be removed, thereby manufacturing Figure 7 the donor substrate 400 shown in (a) of. At this time, the lower electrode of the semiconductor light-emitting element 150 may be loosely bonded to the donor substrate 400. That is, the adhesiveness of the lower surface (i.e., the adhesive surface) of the transfer substrate 201 may be greater than the adhesiveness of the donor substrate 400 in contact with the semiconductor light-emitting element 150.

[0107] As Figure 7 shown in (b) of, the transfer substrate 201 may be lowered and pressed against the donor substrate 400, and then raised again, so that a plurality of semiconductor light-emitting elements 150 on the donor substrate 400 may be picked up onto the transfer substrate 201. At this time, a plurality of semiconductor light-emitting elements 150 on the region corresponding to the area of the transfer substrate 201 may be picked up from the donor substrate 400 onto the transfer substrate 201.

[0108] As Figure 7 shown in (c) of, the transfer substrate 201 that has picked up a plurality of semiconductor light-emitting elements 150 may be moved onto the backplane substrate 300, and then an alignment process may be performed so that the transfer substrate 201 and the backplane substrate 300 may be aligned.

[0109] After that, the transfer substrate 201 may be lowered and pressed, and then raised again, so that a plurality of semiconductor light-emitting elements 150 on the transfer substrate 201 may be placed on the backplane substrate 300.

[0110] The Figure 7 series of transfer processes shown in (a) to Figure 7 (c) of may be repeatedly performed.

[0111] Meanwhile, before describing the transfer substrates 201 to 205 according to the embodiment, various variable relationships related to the transfer substrate will be described with reference to Figures 8 to 10 .

[0112] Figure 8 is a graph showing the relationship between the Young's modulus and the adhesiveness of an organic material.

[0113] As Figure 8 shown, the Young's modulus is inversely proportional to the adhesiveness.

[0114] The Young's modulus is a mechanical property that measures the hardness of a solid material under a certain pressure and can be used interchangeably with stiffness in embodiments. Specifically, the Young's modulus can be an elastic coefficient that defines the relationship between stress and strain in the uniaxial strain region of a linearly elastic material. For example, when the Young's modulus is E, it can be expressed as F (stress) = E (Young's modulus) × S (strain). Therefore, for a material with a larger Young's modulus, the strain is smaller under the same pressure.

[0115] Figure 8 The viscous force shown in [reference] refers to viscosity, and in the case of an organic material, the viscosity of the surface varies according to the hardness. That is, in the case of an organic material, referring to the figure in [reference] Figure 8 In the case of an organic material, as the curing time elapses, the Young's modulus increases and the viscosity changes in the direction of decrease. In other words, as the organic material hardens, the degree of deformation under the same pressure increases while the viscosity decreases.

[0116] Therefore, when the hardness is high, the viscosity decreases, and when the hardness decreases, the viscosity can increase.

[0117] Figure 9 is a graph showing the amount of change of each of the high-viscosity material and the low-viscosity material according to the number of repeated evaluations.

[0118] As Figure 9 shown, as the number of repeated evaluations increases, the amount of change of the high-viscosity material is much larger than that of the low-viscosity material. Therefore, when using a low-viscosity material as the transfer substrate, the possibility of alignment error decreases, while when using a high-viscosity material, the possibility of alignment error increases.

[0119] Figure 10 is a graph showing the yield according to the hardness.

[0120] As Figure 10 shown, it can be seen that as the hardness increases, the yield decreases. Therefore, in order to improve the yield, an organic material with a low hardness can be used as the transfer substrate.

[0121] On the other hand, as Figure 1 shown, in the case of the existing transfer substrate 1, due to the material characteristics of the organic material, deformation (or stretching) occurs as the transfer process is repeated, and there is a problem of poor illumination caused by transfer defects due to alignment errors.

[0122] As Figure 10 shown, in order to improve the yield, an organic material with excellent viscosity but low hardness can be used as the transfer substrate. However, as Figure 8 shown, if the viscosity is high, there is a problem that the hardness decreases and the possibility of alignment error increases.

[0123] In contrast, in order to reduce the possibility of alignment error, an organic material with high hardness but low adhesiveness can be used as the transfer substrate. However, as Figure 10 shown, if the hardness is high, the adhesiveness decreases, and the yield rate decreases.

[0124] In summary, in the case of an organic material, hardness and adhesiveness are inversely proportional. However, an increase in hardness (or a decrease in adhesiveness) may lead to a decrease in the yield rate, and a decrease in hardness (or an increase in adhesiveness) may lead to an increase in the possibility of alignment error. In other words, the yield rate and the possibility of alignment error can also be inversely proportional. Therefore, there is an urgent need to develop a transfer substrate that can reduce alignment error and improve the yield rate.

[0125] Hereinafter, various embodiments of the transfer substrate will be described with reference to Figures 11 to 22 For the various embodiments of the transfer substrate will be described with reference to

[0126] [First Embodiment]

[0127] Figure 11 is a cross-sectional view showing a transfer substrate according to the first embodiment.

[0128] Referring to Figure 11 , the transfer substrate 201 according to the first embodiment may include a stamper member 213.

[0129] The stamper member 213 may include a first layer 215 and a second layer 216. The second layer 216 may be disposed on the first layer 215. The lower surface of the second layer 216 may be in contact with the upper surface of the first layer 215.

[0130] The first layer 215 may be a deformation (or stretching) prevention layer, and the second layer 216 may be an adhesive layer.

[0131] The lower surface of the first layer 215 may be positioned toward the head of the transfer device, and the upper surface of the second layer 216 may be positioned toward the donor substrate 400 or the backplane substrate 300.

[0132] The first layer 215 may include an organic material. The first layer 215 may include a silicon material. For example, the first layer 215 may include polydimethylsiloxane (PDMS), but is not limited thereto. The first layer 215 may include an inorganic filler.

[0133] The first layer 215 may include an inorganic filler. The main component of the inorganic filler may be SiO2 with a thickness of several tens of nm to several μm, but is not limited thereto. The hardness of the first layer 215 can be controlled by the concentration of the inorganic filler. In one embodiment, the first layer 215 is used to support the second layer 216 and must suppress the possibility of alignment error, so that the concentration of the inorganic filler can be relatively high.

[0134] The first layer 215 may include a curing agent. The hardness (or viscosity) of the first layer 215 can be controlled by the amount of the curing agent. That is, as the amount of the curing agent increases, the hardness of the first layer 215 increases, but the viscosity sometimes decreases. On the contrary, as the amount of the curing agent decreases, the hardness of the first layer 215 decreases, but the viscosity can increase.

[0135] In one embodiment, the first layer 215 is used to support the second layer 216 and must suppress the possibility of alignment errors, so that the amount of the curing agent can be relatively high.

[0136] The second layer 216 may include an organic material. The second layer 216 may include a silicon material. The second layer 216 may include the same organic material as the first layer 215. For example, the second layer 216 may include PDMS, but is not limited thereto.

[0137] The second layer 216 may include an inorganic filler. The second layer 216 may include the same inorganic filler as the first layer 215, but is not limited thereto. The hardness of the second layer 216 can be controlled by the concentration of the inorganic filler. In one embodiment, the second layer 216 may have a relatively low concentration of the inorganic filler because the yield must be increased. For example, the concentration of the inorganic filler in the second layer 216 may be lower than the concentration of the inorganic filler in the first layer 215. For example, the concentration of the inorganic filler in the second layer 216 may be at least three times lower than the concentration of the inorganic filler in the first layer 215.

[0138] The first layer 215 may include a curing agent. The hardness (or viscosity) of the second layer 216 can be controlled by the amount of the curing agent. That is, as the amount of the curing agent increases, the hardness of the first layer 215 can increase, but the viscosity can decrease. On the contrary, as the amount of the curing agent decreases, the hardness of the first layer 215 can decrease, but the viscosity can increase.

[0139] In one embodiment, the amount of the curing agent in the second layer 216 can be relatively low because the yield must be increased. The amount of the curing agent in the second layer 216 can be less than the amount of the curing agent in the first layer 215. In this case, the viscosity of the second layer 216 can be greater than the viscosity of the first layer 215, and the hardness of the second layer 216 can be greater than the hardness of the first layer 215 ( Figures 8 to 10 )

[0140] For example, the amount of the curing agent in the first layer 215 can be 11 wt% to 13 wt%, but is not limited thereto. For example, the amount of the curing agent in the second layer 216 can be 9 wt% to 10 wt%, but is not limited thereto.

[0141] Meanwhile, although the thickness of the first layer 215 is shown as greater than that of the second layer 216 in the figure, the thickness of the first layer 215 may be equal to or greater than that of the second layer 216. That is, even if the thickness of the first layer 215 is small, the desired hardness and viscosity can be maintained by controlling the concentration of the inorganic filler and / or the amount of the curing agent in the first layer 215.

[0142] Therefore, when the transfer substrate 201 according to the first embodiment is mounted on the head of the electronic device and the transfer process is performed, the first layer 215 can increase the hardness of the transfer substrate 201, so that even if the transfer process is repeated, the alignment error of the plurality of semiconductor light-emitting elements 150 can be prevented or minimized. In addition, the second layer 216 can increase the viscosity of the transfer substrate 201, thereby improving the yield. That is, the higher the viscosity of the transfer substrate 201, the greater the possibility that the plurality of semiconductor light-emitting elements 150 are picked up from the donor substrate 400 without omission onto the transfer substrate 201 and the plurality of semiconductor light-emitting elements 150 are placed onto the backplane substrate 300 without omission.

[0143] Meanwhile, the transfer substrate 201 according to the first embodiment may include a support member 211. When the first layer 215 of the stamper member 213 functions as the support member 211 while preventing the alignment error of the semiconductor light-emitting elements 150, the support member 211 can be omitted.

[0144] The support member 211 can support the stamper member 213 and enable the stamper member 213 to be easily and stably mounted on the head of the transfer device. In addition, the support member 211 can enable the stamper member 213 to be easily and stably detached from the head of the transfer device. The support member 211 can enable the pressing force of the head of the transfer device to be evenly transmitted to the entire area of the stamper member 213. Therefore, the support member 211 can be made of a material having excellent support strength.

[0145] The support member 211 can be disposed below the first layer 215. The support member 211 may include an organic material different from the first layer 215, but is not limited thereto. The second layer 216 may include a plastic material or glass. As the plastic material, polyethylene terephthalate (PET), polycarboxylate ether (PCE), etc. can be used.

[0146] The support member 211 can be attached to the stamper member 213 using double-sided tape, but is not limited thereto. For example, after positioning the double-sided tape between the stamper member 213 and the support member 211, the stamper member 213 and / or the support member 211 is pressed so that the support member 211 can be attached to the stamper member 213 using double-sided tape.

[0147] Figure 12It is a flowchart showing a method for manufacturing a transfer substrate according to the first embodiment.

[0148] As Figure 11 and Figure 12 shown, a mold 500 can be prepared (S511).

[0149] A groove corresponding to the size of the transfer substrate 201 can be provided inside the mold 500.

[0150] The first mixed solution 520 can be injected onto the mold 500. For example, the first mixed solution 520 can be injected into the groove of the mold 500 (S512).

[0151] The first mixed solution 520 is a solution for forming the second layer 216 and can be prepared by mixing an organic material, a curing agent, etc. The first mixed solution 520 may include inorganic fillers, but is not limited thereto. The injection amount of the first mixed solution 520 can be determined in consideration of the thickness of the second layer 216.

[0152] The second mixed solution 530 can be injected onto the first mixed solution 520 (S513). For example, the second mixed solution 530 can be injected onto the first mixed solution 520 in the groove of the mold 500.

[0153] The second mixed solution 530 is a solution for forming the first layer 215 and can be prepared by mixing an organic material, a curing agent, etc. The second mixed solution 530 may include inorganic fillers, but is not limited thereto. The injection amount of the second mixed solution 530 can be determined in consideration of the thickness of the first layer 215.

[0154] The organic material of the second mixed solution 530 can be the same as that of the first mixed solution 520, but is not limited thereto. The curing agent of the second mixed solution 530 can be the same as that of the first mixed solution 520, but is not limited thereto. The inorganic filler of the second mixed solution 530 can be the same as that of the first mixed solution 520, but is not limited thereto.

[0155] Meanwhile, since the first mixed solution 520 and the second mixed solution 530 include a silicon material with a relatively high viscosity as the organic material and have different contents of the curing agent, the first mixed solution 520 and the second mixed solution 530 injected into the groove of the mold 500 may not mix at the interface, but may form independent layers with each other.

[0156] In this way, the first mixed solution 520 and the second mixed solution 530, which are formed as independent layers in the grooves of the mold 500, can be cured simultaneously (S514). Accordingly, the cured first mixed solution 520 can be formed as the first layer 215, and the cured second mixed solution 530 can be formed as the second layer 216 on the first layer 215. Accordingly, the stamp member 213 including the first layer 215 and the second layer 216 can be formed.

[0157] Thereafter, the stamp member 213 can be attached to the support member 211 using a double-sided tape, but is not limited thereto. For example, after the double-sided tape is positioned between the first layer 215 of the stamp member 213 and the support member 211, the first layer 215 of the stamp member 213 and / or the mold 500 can be pressed so that the support member 211 can be attached to the stamp member 213 via the double-sided tape.

[0158] Thereafter, the mold 500 can be removed (S515) so that the transfer substrate 201 including the stamp member 213 and the support member 211 can be manufactured.

[0159] In the above, the second layer 216, the first layer 215, and the support member 211 are described as being formed in sequence, but the support member 211, the first layer 215, and the second layer 216 can be formed in sequence. Alternatively, the first layer 215 and the second layer 216 can be sequentially formed on the mold 500, and after the mold 500 is removed, the support member 211 can be formed under the first layer 215.

[0160] [Second Embodiment]

[0161] Figure 13 is a top view showing a transfer substrate according to the second embodiment. Figure 14 is a cross-sectional view showing a transfer substrate according to the second embodiment.

[0162] The second embodiment is the same as the first embodiment except that the second layer 216 includes a plurality of protrusions 216a and recesses 216b. In the second embodiment, components having the same shape, structure, and / or function as those in the first embodiment are given the same reference numerals, and their detailed descriptions are omitted.

[0163] Reference Figure 13 and Figure 14 , the transfer substrate 202 according to the second embodiment may include a support member 211 and a stamp member 213. The support member 211 can be omitted when the first layer 215 of the stamp member 213 functions as the support member 211 while preventing alignment errors of the semiconductor light-emitting elements 150.

[0164] The stamp member 213 can be disposed on the support member 211.

[0165] The support member 211 can be installed on the head of the transfer device. The imprint member 213 can be configured to prevent alignment errors of the semiconductor light-emitting elements 150 while increasing the yield.

[0166] The imprint member 213 can include a first layer 215 and a second layer 216. The first layer 215 can be disposed on the support member 211. The first layer 215 can be in contact with the upper surface of the support member 211. The second layer 216 can be disposed on the first layer 215. The second layer 216 can be in contact with the upper surface of the first layer 215.

[0167] In one embodiment, the second layer 216 can include a plurality of protrusions 216a and recesses 216b. The protrusions 216a can protrude from the upper surface of the first layer 215 in an upward direction. As Figure 13 shown, when viewed from above, the protrusions 216a can have a square shape, but are not limited thereto.

[0168] The plurality of protrusions 216a can be spaced apart from each other, and the spaced-apart spaces can be the recesses 216b. At this time, the width (or gap) of the recesses 216b can be designed in consideration of the gap or margin between the pixels.

[0169] That is, the recesses 216b can be positioned along the periphery of each of the plurality of protrusions 216a. The recesses 216b positioned along the periphery of each of the plurality of protrusions 216a can be connected to each other. The depth of the recesses 216b can be determined by the thickness (or height) of the protrusions 216a. That is, the depth of the recesses 216b can be the same as the thickness of the protrusions 216a. The greater the thickness of the protrusions 216a, the greater the depth of the recesses 216b.

[0170] Meanwhile, the plurality of protrusions 216a can each correspond to pixels defined on the backplane substrate 300. As Figure 15 shown, the transfer substrate 202 according to the second embodiment can be positioned on the backplane substrate 300 in the case of picking up a plurality of semiconductor light-emitting elements 150. In this case, the plurality of protrusions 216a of the transfer substrate 202 can each have a size corresponding to the size of at least one of the pixels PX1 to PX5. The protrusions 216a can have a shape corresponding to the shape of the pixels PX1 to PX5. For example, when the pixels PX1 to PX5 have a square shape, the protrusions 216a can also have a square shape.

[0171] The pixels PX1 to PX5 can include a plurality of semiconductor light-emitting elements 150. That is, the pixels PX1 to PX5 can include a plurality of sub-pixels. In this case, the sub-pixels can include at least one or more semiconductor light-emitting elements 150.

[0172] For example, pixels PX1 to PX5 may include a first sub-pixel, a second sub-pixel, and a third sub-pixel. In this case, the first sub-pixel may include at least one or more first semiconductor light-emitting elements 150R. The second sub-pixel may include at least one or more second semiconductor light-emitting elements 150G. The third sub-pixel may include at least one or more third semiconductor light-emitting elements 150B. For example, the first semiconductor light-emitting element 150R may include a red semiconductor light-emitting element that emits red light, the second semiconductor light-emitting element 150G may include a green semiconductor light-emitting element that emits green light, and the third semiconductor light-emitting element 150B may include a blue semiconductor light-emitting element that emits blue light.

[0173] When the protrusion 216a has a size corresponding to the size of the pixels PX1 to PX5 including the first sub-pixel to the third sub-pixel, as Figure 16 shown in (a) of, the first semiconductor light-emitting element 150R to the third semiconductor light-emitting element 150B arranged in a row among the plurality of semiconductor light-emitting elements 150 on the donor substrate 400 can be picked up on the protrusion 216a of the transfer substrate 202. When the first semiconductor light-emitting element 150R to the third semiconductor light-emitting element 150B picked up on the protrusion 216a of the transfer substrate 202 are placed on the backplane substrate 300, the first semiconductor light-emitting element 150R to the third semiconductor light-emitting element 150B can be located on each of the first sub-pixel to the third sub-pixel of the pixels PX1 to PX5 on the backplane substrate 300. In this case, the first semiconductor light-emitting element 150R to the third semiconductor light-emitting element 150B can be transferred to the pixels PX1 to PX5 corresponding to the number of protrusions 216a of the transfer substrate 202 through a single transfer process of the transfer substrate 202. For example, when 100 pixels are defined on the backplane substrate 300 and the number of protrusions 216a of the transfer substrate 202 is 50, the semiconductor light-emitting elements 150 can be transferred to all the pixels of the backplane substrate 300 through two transfer processes using the transfer substrate 202.

[0174] Meanwhile, in addition to the first sub-pixel to the third sub-pixel, the pixels PX1 to PX5 may include a fourth sub-pixel. The fourth sub-pixel may not have the semiconductor light-emitting elements 150R, 150G, and 150B disposed therein.

[0175] In addition, in addition to the first sub-pixel to the third sub-pixel, pixels PX1 to PX5 may include one or more additional sub-pixels. Each additional sub-pixel may include at least one or more semiconductor light-emitting elements among the first semiconductor light-emitting element 150R to the third semiconductor light-emitting element 150B. For example, the fourth sub-pixel may include the first semiconductor light-emitting element 150R, the fifth sub-pixel may include the second semiconductor light-emitting element 150G, and the sixth sub-pixel may include the third semiconductor light-emitting element 150B.

[0176] As Figure 15 and Figure 16 As shown in (b) of

[0177] In this case, the first semiconductor light-emitting element 150R to the third semiconductor light-emitting element 150B may be located in each of the first sub-pixel to the third sub-pixel, and the fourth semiconductor light-emitting element 150R' to the sixth semiconductor light-emitting element 150B' may be located in each of the fourth sub-pixel to the sixth sub-pixel. The first semiconductor light-emitting element 150R and the fourth semiconductor light-emitting element 150R' may each emit red light. The second semiconductor light-emitting element 150G and the fifth semiconductor light-emitting element 150G' may each emit green light. The third semiconductor light-emitting element 150B and the sixth semiconductor light-emitting element 150B' may each emit blue light.

[0178] For example, the fourth semiconductor light-emitting element 150R' to the sixth semiconductor light-emitting element 150B' are redundant semiconductor light-emitting elements and may be used as replacements when the first semiconductor light-emitting element 150R to the third semiconductor light-emitting element 150B have poor illumination. For example, when the display device including the backplane substrate 300 is driven to implement a display, when the first semiconductor light-emitting element 150R has poor illumination, the fourth semiconductor light-emitting element 150R' may be used as a replacement for the first semiconductor light-emitting element 150R. Therefore, even if a specific semiconductor light-emitting element has poor illumination when implementing a display, the replacement semiconductor light-emitting element will light up, so that deterioration of image quality can be prevented.

[0179] Meanwhile, the first pixel may be defined by the first sub-pixel to the third sub-pixel, in which the first semiconductor light-emitting element 150R to the third semiconductor light-emitting element 150B are respectively located, and the second pixel may be defined by the fourth sub-pixel to the sixth sub-pixel, in which the fourth semiconductor light-emitting element 150R' to the sixth semiconductor light-emitting element 150B' are respectively located. In this case, as Figure 16As shown in (b), two pixels corresponding to the first semiconductor light-emitting element 150R to the sixth semiconductor light-emitting element 150B' (i.e., the first pixel and the second pixel) can be transferred onto the backplane substrate 300 through one protrusion 216a.

[0180] Therefore, multiple semiconductor light-emitting elements can be transferred onto pixels in an amount twice the number of protrusions 216a of the transfer substrate 202. For example, when 100 pixels are defined on the backplane substrate 300 and the number of protrusions 216a of the transfer substrate 202 is 50, the semiconductor light-emitting elements can be transferred onto all the pixels of the backplane substrate 300 by a single transfer process using the transfer substrate 202.

[0181] Although not shown, the protrusion 216a can have a size corresponding to the size of three or more sub-pixels.

[0182] According to an embodiment, the second layer 216 includes multiple protrusions 216a, and the size of each protrusion 216a corresponds to the size of at least one or more pixels, so that the alignment adjustment of each of the multiple pixels on the backplane substrate 300 can be facilitated, and the alignment accuracy can be improved. In addition, according to an embodiment, since adjacent protrusions 216a do not affect each other, even if a specific protrusion 216a is deformed, the surrounding protrusions 216a will not be affected by the deformation of the specific protrusion 216a, so that an increase in cost caused by the rejection of the backplane substrate 300 during the transfer process can be prevented.

[0183] Figure 17 is a cross-sectional view showing a method for manufacturing a transfer substrate according to the second embodiment.

[0184] As Figure 17 shown in (a), a mold 500 having multiple negative patterns 510 can be prepared.

[0185] As Figure 17 shown in (b), a first mixed solution 520 can be injected onto the mold 500. The first mixed solution 520 can be a solution for forming the second layer 216. In this case, the first mixed solution 520 can be filled into the multiple negative patterns 510 of the mold 500. Thereafter, the first mixed solution 520 overflowing from the multiple negative patterns 510 can be removed using a squeegee. Therefore, the first mixed solution 520 can be filled only into the multiple negative patterns 510.

[0186] Meanwhile, a second mixed solution 530 can be injected onto the mold 500 (S530). Therefore, as Figure 17As shown in (c), the second mixed solution 530 may be formed on the first mixed solution 520. In this case, the first mixed solution 520 and the second mixed solution 530 may remain unmixed and may exist as separate layers centered on the interface between the first mixed solution 520 and the second mixed solution 530.

[0187] Thereafter, the first mixed solution 520 and the second mixed solution 530 may harden to form the impression member 213.

[0188] As Figure 17 shown in (d), the support member 211 may be attached to the impression member 213 using double-sided tape, but is not limited thereto.

[0189] First, the support member 211 may be positioned on the first layer 215 of the impression member 213, and the double-sided tape may be positioned between the support member 211 and the impression member 213. One side of the double-sided tape may be pre-attached to the upper surface of the first layer 215 of the impression member 213 or the lower surface of the support member 211. Then, the first layer 215 of the impression member 213 and / or the mold 500 may be pressed, allowing the impression member 213 to be attached to the support member 211 via the double-sided tape.

[0190] As Figure 17 shown in (e), by removing the mold 500, a transfer substrate 202 including the impression member 213 and the support member 211 may be manufactured.

[0191] [Third Embodiment]

[0192] Figure 18 is a cross-sectional view showing a transfer substrate according to the third embodiment.

[0193] Except for the third layer 217, the third embodiment is the same as the second embodiment. In the third embodiment, components having the same shape, structure, and / or function as those in the second embodiment are given the same reference numerals, and their detailed descriptions are omitted.

[0194] Referring Figure 18 to, the transfer substrate 203 according to the third embodiment may include a support member 211 and an impression member 213. When the first layer 215 of the impression member 213 functions as the support member 211 while preventing alignment errors of semiconductor light-emitting elements, the support member 211 may be omitted.

[0195] The impression member 213 may include a first layer 215 and a second layer 216. The first layer 215 may be provided on the support member 211. The first layer 215 may be in contact with the upper surface of the support member 211. The second layer 216 may be provided on the first layer 215. The second layer 216 may be in contact with the upper surface of the first layer 215.

[0196] In one embodiment, the second layer 216 may include a plurality of protrusions 216a and recesses 216b. The protrusions 216a may protrude upward from the upper surface of the first layer 215 in an upward direction.

[0197] The plurality of protrusions 216a may be spaced apart from each other, and the spaced-apart spaces may be recesses 216b. That is, the recesses 216b may be positioned around each of the plurality of protrusions 216a.

[0198] Since the plurality of protrusions 216a are spaced apart from each other, when the transfer process is repeated, the plurality of protrusions 216a may be deformed (or stretched) in the lateral direction by the continuous pressure of the first layer 215. There is a problem of alignment error of the semiconductor light-emitting elements due to this deformation, resulting in poor illumination.

[0199] To solve this problem, in an embodiment, the stamper member 213 may include a third layer 217. The third layer 217 may be disposed in the recesses 216b.

[0200] The third layer 217 may prevent the occurrence of deformation of the second layer 216. That is, since the third layer 217 is buried in the recesses 216b, the third layer 217 may contact the side surfaces of each protrusion 216a adjacent to the bottom surface of the recesses 216b. Therefore, when the pressing force of the first layer 215 is transmitted to the protrusions 216a of the second layer 216, causing the protrusions 216a of the second layer 216 to be stretched in the lateral direction, the stretching can be suppressed by the third layer 217 disposed in the recesses 216b. Therefore, even if the transfer process is repeatedly performed, since the protrusions 216a of the second layer 216 are not stretched in the lateral direction by the third layer 217, the occurrence of alignment error of the semiconductor light-emitting elements 150 can be prevented, thereby preventing poor illumination.

[0201] In order for the third layer 217 to prevent the stretching of the second layer 216, the third layer 217 may include the same organic material as the first layer 215 and the second layer 216. At this time, the amount of the curing agent of the third layer 217 may be equal to or less than the amount of the curing agent of the first layer 215. The amount of the curing agent of the third layer 217 may be greater than the amount of the curing agent of the protrusions 216a of the second layer 216. For example, the amount of the curing agent of the third layer 217 may exceed 10 wt% and be equal to or less than 13 wt%. Therefore, the viscosity of the third layer 217 may be equal to or greater than the viscosity of the first layer 215. The viscosity of the third layer 217 may be less than the viscosity of the second layer 216. The hardness of the third layer 217 may be equal to or less than the hardness of the first layer 215. The hardness of the third layer 217 may be greater than the hardness of the second layer 216.

[0202] The thickness t2 of the third layer 217 may be less than the thickness t1 of the protrusion 216a, but is not limited thereto. Accordingly, the third layer 217 and the protrusion 216a are clearly distinguishable, which helps with alignment, and the third layer 217 is not damaged by the impact on the partition wall of the backplane substrate during the transfer of the transfer substrate 203.

[0203] Meanwhile, in Figure 18 the first layer 215 and the third layer 217 are distinguished as separate layers, but the first layer 215 and the third layer 217 may be integrally formed. That is, the third layer 217 may be an extension extending to the first layer 215. In other words, the extension may extend from the first layer 215 to the recess 216b between the adjacent protrusions 216a of the second layer 216.

[0204] For example, after the first layer 215 and the third layer 217 are simultaneously formed on the mold 500 using the same molding process and the mold 500 is removed, the protrusions 216a of the second layer 216 may be formed on the third layer 217 on the first layer 215, that is, on the area where the extension is not formed, thereby manufacturing the stamper member 213.

[0205] [Fourth Embodiment]

[0206] Figure 19 is a cross-sectional view showing a transfer substrate according to the fourth embodiment.

[0207] Except for the fourth layer 218, the fourth embodiment is the same as the first embodiment. In the fourth embodiment, components having the same shape, structure, and / or function as those in the first embodiment are given the same reference numerals, and their detailed descriptions are omitted. The fourth embodiment can be similarly applied to the second embodiment or the third embodiment.

[0208] Referring to Figure 19 , the transfer substrate 204 according to the fourth embodiment may include a stamper member 213. The stamper member 213 may include a first layer 215 and a second layer 216.

[0209] The transfer substrate 204 according to the fourth embodiment may include a fourth layer 218.

[0210] The fourth layer 218 may be disposed below the stamper member 213. The fourth layer 218 may be disposed below the first layer 215 of the stamper member 213. The fourth layer 218 may be in contact with the lower surface of the first layer 215 of the stamper member 213.

[0211] In an embodiment, in order to distinguish it from the Figure 18 shown third layer 217, it is named the fourth layer 218, but considering the Figure 19 shown number of layers, it may also be named the third layer 217.

[0212] The fourth layer 218 may include the same organic material as the first layer 215 and the second layer 216. That is, the first layer 215, the second layer 216, and the fourth layer 218 may include a silicon material. For example, the first layer 215, the second layer 216, and the fourth layer 218 may include PDMS, but are not limited thereto.

[0213] The amount of the curing agent in the fourth layer 218 may be greater than the amount of the curing agent in the first layer 215. The amount of the curing agent in the fourth layer 218 may be greater than the amount of the curing agent in the second layer 216. For example, the amount of the curing agent in the fourth layer 218 may be at least twice the amount of the curing agent in the second layer 216. For example, the amount of the curing agent in the fourth layer 218 may be 20 wt% or more. Therefore, the hardness of the fourth layer 218 may be greater than the hardness of the first layer 215 or the second layer 216, and the viscosity of the fourth layer 218 may be less than the viscosity of the first layer 215 or the second layer 216.

[0214] The fourth layer 218 may replace the support member 211 of the transfer substrate 204 according to the first embodiment. That is, the fourth layer 218 may have the function of the corresponding support member 211.

[0215] As described above, the support member 211 may be attached to the stamper member 213 using a double-sided tape. When the support member 211 or the stamper member 213 is pressed for such attachment, deformation (or stretching) may occur in the stamper member 213, particularly in the second layer 216. When the stamper member 213 is attached to the support member 211 in this deformed state, the alignment position set on the stamper member 213 may be disturbed, and in the repeated transfer process, continuous deformation may be caused due to the repeated pressing of the deformed second layer 216. Therefore, there is a problem that alignment errors of the semiconductor light-emitting elements 150 continuously occur, resulting in the abandonment of the transfer substrate 204.

[0216] To solve this problem, according to an embodiment, since a double-sided tape is not used, a pressing process is not required, and thus deformation of the second layer 216 of the stamper member 213 may not occur. That is, the first layer 215, the second layer 216, and the fourth layer 218 may be formed using a molding process.

[0217] For example, when performing Figure 12After S513 shown, the third mixed solution can be injected onto the mold 500. The third mixed solution can be injected onto the second mixed solution 530, and the second mixed solution 530 is injected into the groove of the mold 500. The third mixed solution can be a solution for forming the fourth layer 218 and can be prepared by mixing an organic material, a curing agent, etc. The second mixed solution 530 can include an inorganic filler, but is not limited thereto. The injection amount of the third mixed solution can be determined in consideration of the thickness of the fourth layer 218. Thereafter, the first mixed solution 520 to the third mixed solution are cured simultaneously, such that a stamper member 213 including the first layer 215, the second layer 216, and the fourth layer 218, that is, a transfer substrate 204, can be manufactured. The transfer substrate 204 can include the fourth layer 218, the first layer 215 on the fourth layer 218, and the second layer 216 on the first layer 215.

[0218] Meanwhile, as Figure 2 shown, when the transfer substrate 1 is pressed to be transferred to a specific block area 7 of the backplane substrate 3, the stress of the transfer substrate 1 can be transferred to the block area 310 adjacent to the specific block area 310. In this case, when a plurality of semiconductor light-emitting elements 5 have been transferred between the peripheral block areas 310, there is a problem that the plurality of semiconductor light-emitting elements 5 are also warped or bent, resulting in poor lighting due to electrical disconnection during post-processing. In addition, when the plurality of semiconductor light-emitting elements 5 are also warped or bent, there is a problem that the transferred semiconductor light-emitting elements come off the backplane substrate 3.

[0219] The fifth embodiment is an embodiment proposed to solve this problem and will be described in detail with reference to Figures 20 to 22 .

[0220] [Fifth Embodiment]

[0221] Figure 20 is a top view showing a transfer substrate according to the fifth embodiment. Figure 21 is a cross-sectional view showing a transfer substrate according to the fifth embodiment.

[0222] Except for the recess 219, the fifth embodiment is similar to the first embodiment. In the fifth embodiment, components having the same shape, structure, and / or function as those of the first embodiment are given the same reference numerals, and their detailed descriptions are omitted. The fifth embodiment can be similarly applied to the second embodiment, the third embodiment, and / or the fourth embodiment.

[0223] Refer to Figure 20 and Figure 21, the transfer substrate 205 according to the fifth embodiment may include a support member 211 and a stamper member 213. When the first layer 215 of the stamper member 213 functions as the support member 211 while preventing misalignment of the semiconductor light-emitting elements 150, the support member 211 may be omitted.

[0224] The stamper member 213 may include a first layer 215 and a second layer 216.

[0225] The area A1 of the first layer 215 may be larger than the area A2 of the second layer 216. The second layer 216 may have a size corresponding to the total size of the plurality of pixels. The first layer 215 may have a first region and a second region surrounding the first region. In this case, the first region of the first layer 215 may vertically overlap the second layer 216. The area of the first region of the first layer 215 may be equal to the area A2 of the second layer 216. The second region of the first layer 215 may not vertically overlap the second layer 216. That is, the upper surface of the second region of the first layer 215 is not covered by the second layer 216 and thus may be exposed to the outside.

[0226] Meanwhile, a recess 219 may be formed in the first layer 215. The recess 219 may be formed on the upper surface of the first layer 215. The recess 219 may be recessed inward from the upper surface of the first layer 215. The recess 219 may be formed in the second region of the first layer 215. The recess 219 may be formed on the upper surface of the second region of the first layer 215. The recess 219 may surround the first region of the first layer 215. The recess 219 may be formed along the perimeter of the outside of the second layer 216. The recess 219 may be positioned to be spaced apart from the outside of the second layer 216, but is not limited thereto.

[0227] The recess 219 formed in this way may be used to absorb stress generated when the transfer substrate 205 is pressed. The stress transmitted from the support member 211 to the first layer 215 or the second layer 216 may be transmitted to the edge region of the first layer 215 and absorbed by the recess 219.

[0228] Although the drawings illustrate the recess 219 as having a closed-loop structure along the perimeter of the outside of the second layer 216, the recess 219 may also have a pattern structure spaced apart from each other along the perimeter of the outside of the second layer 216. The drawings show the recess 219 as having an inner side perpendicular to the ground, but it may be inclined or circular.

[0229] As Figure 22As shown, the transfer substrate 205 according to the fifth embodiment can be pressed against a specific block area 310 of the backplane substrate 300, such that a plurality of semiconductor light-emitting elements 150 on the transfer substrate 205 can be transferred onto the specific block. At this time, the stress generated on the transfer substrate 205 can be transferred to the edge area, and the stress transferred to the edge area can be absorbed by the recess 219. In this way, since the stress generated on the transfer substrate 205 is absorbed by the recess 219, the stress on the transfer substrate 205 is not transferred to the surrounding block area 310 adjacent to the transfer substrate 205, such that the plurality of semiconductor light-emitting elements 150 that have been transferred onto the surrounding block area 310 can be prevented from warping or bending. Therefore, poor lighting caused by electrical disconnection due to post-processing can be prevented, or the semiconductor light-emitting elements 150 can be prevented from detaching from the surrounding block area 310.

[0230] Meanwhile, as described above, the first mixed solution 520 and the second mixed solution 530 can be injected onto the mold 500 by an injection method. However, alternatively, the first mixed solution 520 and the second mixed solution 530 can be coated onto the mold 500 by using a coating method.

[0231] Meanwhile, the above-described display device can be a display panel. That is, in the present embodiment, the display device and the display panel can be understood to have the same meaning. In the present embodiment, the actual display device can include a display panel and a controller (or processor) that can control the display panel to display an image.

[0232] The above detailed description should not be construed as restrictive in all respects, but rather as illustrative. The scope of the present embodiment should be determined by a reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present embodiment are included within the scope of the present embodiment.

[0233] Industrial Applicability

[0234] The present embodiment can be applied in the display field for displaying images or information. The present embodiment can be applied in the display field for using semiconductor light-emitting elements to display images or information. The semiconductor light-emitting elements can be micron-scale semiconductor light-emitting elements or nano-scale semiconductor light-emitting elements.

[0235] For example, the embodiment can be used in TVs, signage, smart phones, mobile phones, mobile terminals, HUDs for automobiles, backlight units for laptop computers, and display devices for VR, AR, or MR.

Claims

1. A transfer substrate, the transfer substrate comprising: A first layer; And A second layer on the first layer, Wherein, the amount of the curing agent in the second layer is less than the amount of the curing agent in the first layer, Wherein, the viscosity of the second layer is greater than the viscosity of the first layer, and Wherein, the hardness of the second layer is less than the hardness of the first layer.

2. The transfer substrate according to claim 1, wherein, The amount of the curing agent in the first layer is 11 wt% to 13 wt%, and the amount of the curing agent in the second layer is 9 wt% to 10 wt%.

3. The transfer substrate according to claim 2, wherein, The second layer comprises: A plurality of protrusions; and Recesses surrounding each of the plurality of protrusions.

4. The transfer substrate according to claim 3, wherein, Each of the plurality of protrusions has a size corresponding to the size of at least one pixel, and Wherein, the pixel comprises a plurality of sub-pixels respectively corresponding to a plurality of semiconductor light-emitting elements.

5. The transfer substrate according to claim 3, the transfer substrate comprising: A third layer in the recesses.

6. The transfer substrate according to claim 5, wherein, The first layer to the third layer comprise the same organic material, and Wherein, the amount of the curing agent in the third layer is equal to or less than the amount of the curing agent in the first layer and greater than the amount of the curing agent in the protrusions.

7. The transfer substrate according to claim 6, wherein, The viscosity of the third layer is equal to or greater than the viscosity of the first layer and less than the viscosity of the second layer, and Wherein, the hardness of the third layer is equal to or less than the hardness of the first layer and greater than the hardness of the second layer.

8. The transfer substrate according to claim 5, wherein, The third layer is an extension extending from the first layer.

9. The transfer substrate according to claim 5, wherein, The thickness of the third layer is less than the thickness of the protrusions.

10. The transfer substrate according to claim 1, the transfer substrate comprising a support member under the first layer, Among them, The support member and the first layer comprise different organic materials.

11. The transfer substrate according to claim 10, wherein, The support member comprises a plastic material, and Wherein, the first layer and the second layer comprise a silicon material.

12. The transfer substrate according to claim 1, the transfer substrate comprising a fourth layer under the first layer, Among them, The first layer, the second layer and the fourth layer comprise the same organic material, and Wherein, the amount of the curing agent in the fourth layer is greater than the amount of the curing agent in the first layer.

13. The transfer substrate according to claim 12, wherein, The amount of the curing agent in the fourth layer is at least twice the amount of the curing agent in the second layer.

14. The transfer substrate according to claim 1, wherein, The area of the first layer is greater than the area of the second layer, The transfer substrate comprises: A second recess along the periphery of the outer side of the second layer in the edge region of the upper surface of the first layer.

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