Transfer printing mold for light-emitting element and manufacturing method of transfer printing mold

Abstract

The invention discloses a light-emitting element transfer stamp and a manufacturing method thereof. The light emitting element transfer stamp disclosed herein includes: a stamp substrate; a plurality of insertion grooves disposed at regular intervals in the stamp substrate; a plurality of adhesive layers respectively disposed in the plurality of insertion grooves and on the stamp substrate in contact with the insertion grooves; a passivation layer disposed on the stamp substrate between the plurality of adhesive layers; and a buffer layer disposed on a rear surface of the stamp substrate.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0134764, filed on October 11, 2023, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to a light-emitting display device, and more particularly to a light-emitting element transfer stamp and a manufacturing method thereof. Background Art

[0004] As technology develops, display devices including self-luminous elements are developed. Display devices including self-luminous elements may include: organic light-emitting display devices including organic materials as light-emitting layers; and micro LED display devices using micro light-emitting elements.

[0005] A micro-light-emitting element refers to an ultra-small light-emitting element having a size of several tens of micrometers or less. By using such a micro-light-emitting element as a pixel, a device can be miniaturized and lit. However, since the micro-light-emitting element is very small in size and a large number of light-emitting elements need to be formed, there is a problem that considerable manufacturing cost and time are required.

[0006] In order to manufacture a display device using a micro-light-emitting element, the micro-light-emitting element may be crystallized on a substrate such as sapphire or silicon, and the crystallized micro-light-emitting element may be transferred to a substrate having a driving circuit. The process of transferring the micro-light-emitting element may adopt a method of stamping a stamp substrate having the micro-light-emitting element formed thereon to a transfer substrate having the driving circuit formed thereon.

[0007] However, when the size of the micro light emitting element is reduced, the transfer may not be performed well, and since a pucked-up stamp substrate cannot be used multiple times, it is necessary to remove the existing stamp substrate and insert another stamp substrate after imprinting, which complicates the process.

[0008] Furthermore, since a high voltage input is required to maintain electrostatic force when picking up a micro light emitting element via Mesa, it is susceptible to shorting damage of a fine structure.

[0009] Due to the fragility of a fine spring used for leveling when picking up a micro light-emitting element, the variability of the pickup transfer rate may be high depending on the stiffness of the manufactured spring.

[0010] Furthermore, stress concentration due to repeated use of the stamp may cause damage such as breakage of the spring, thereby causing damage to the surface of the micro light-emitting element due to the spring.

[0011] Furthermore, since expensive wafer materials and complicated manufacturing processes are required, component costs are increased and manufacturing yields are limited. Summary of the invention

[0012] An object of the present invention is to address the above-mentioned needs and / or problems.

[0013] The present invention aims to provide a light emitting element transfer stamp and a method for manufacturing the same, which can improve transfer yield by using a material having flexible adhesive properties and can reduce manufacturing costs by simplifying the process.

[0014] The present invention also aims to provide a light emitting element transfer stamp and a method for manufacturing the same, which can improve the ability to suppress lateral shrinkage and expansion due to heat, thereby ultimately increasing the pattern accuracy of chip transfer.

[0015] The problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned herein will be clearly understood by a person of ordinary skill in the art from the following description.

[0016] According to one embodiment of the present invention, a light-emitting element transfer stamp includes: a stamp substrate; a plurality of insertion grooves arranged in the stamp substrate at regular intervals; a plurality of adhesive layers, which are respectively arranged in the plurality of insertion grooves and on the stamp substrate in contact with the insertion grooves; a passivation layer arranged on the stamp substrate between the plurality of adhesive layers; and a buffer layer arranged on the rear surface of the stamp substrate.

[0017] According to one embodiment of the present invention, a method for manufacturing a light-emitting element transfer stamp includes: forming a plurality of insertion grooves at regular intervals in a stamp substrate; disposing a plurality of adhesive layers in the plurality of insertion grooves and on the stamp substrate in contact with the plurality of insertion grooves; disposing a passivation layer on the stamp substrate between the plurality of adhesive layers; and disposing a buffer layer on the rear surface of the stamp substrate.

[0018] According to the present invention, by using a stamp structure that allows the light emitting element to be picked up and placed without complicated spring structures and voltage application, a pick / place transfer process is possible via a simple adhesive material process and a low temperature heating control method.

[0019] According to the present invention, the risk of light emitting element chip damage (micro LED chip damage risk) can be reduced, the yield loss and damage due to pickup array component defects can be improved, and the component life can be increased.

[0020] According to the present invention, by providing a buffer layer on the rear surface of a stamp substrate on which a light emitting element is picked up, a stamp substrate can be formed so that face-to-face adhesion balance is favorable during a pick / place process, thereby expecting improvement in yield.

[0021] According to the present invention, since a fine microstructure does not exist except for the PDMS material used as the adhesive layer material, the life of the stamp can be improved.

[0022] According to the present invention, the manufacturing process of the stamp is simple, thereby reducing the manufacturing cost and being advantageous in terms of component consistency.

[0023] The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and other objects, features and advantages of the present invention will become more apparent to those skilled in the art through exemplary embodiments described in detail with reference to the accompanying drawings, in which:

[0025] Figure 1 is a diagram schematically illustrating a display device according to an embodiment of the present invention;

[0026] Figure 2 yes Figure 1 An enlarged view of area A in FIG.

[0027] Figure 3 is a diagram showing a local area of ​​a pixel;

[0028] Figure 4 is along Figure 3 A cross-sectional view taken along line IV-IV';

[0029] Figure 5 is along Figure 3 A cross-sectional view taken along line V-V';

[0030] Figures 6A to 6C is a perspective view schematically illustrating a state in which, for a display device according to an embodiment of the present invention, a light emitting element is transferred onto a transfer substrate using a light emitting element transfer stamp;

[0031] Figure 7 is a plan view illustrating a light emitting element transfer stamp for a display device according to an embodiment of the present invention;

[0032] Figure 8 is along Figure 7 A cross-sectional view taken along line VIII-VIII';

[0033] Figures 9A to 9Jis a cross-sectional view illustrating a manufacturing process of a light emitting element transfer stamp for a display device according to an embodiment of the present invention;

[0034] Figures 10A to 10G is a cross-sectional view illustrating a process of transferring a light emitting element onto a transfer substrate using a light emitting element transfer stamp for a display device according to an embodiment of the present invention;

[0035] Fig.11 is a cross-sectional view illustrating a light emitting element transfer stamp according to another embodiment of the present invention;

[0036] Fig.12 is a cross-sectional view illustrating a light emitting element transfer stamp according to still another embodiment of the present invention;

[0037] Fig.13 is a cross-sectional view illustrating a light emitting element transfer stamp according to still another embodiment of the present invention;

[0038] Fig.14 is a cross-sectional view illustrating a light emitting element transfer stamp according to still another embodiment of the present invention. DETAILED DESCRIPTION

[0039] The advantages and features of the present invention and methods for implementing the same will become clear through the embodiments described in detail below in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments below, which can be implemented in various different forms. Rather, the embodiments of the present invention will make the disclosure of the present invention complete and allow those of ordinary skill in the art to fully understand the scope of the present invention. The present invention is only limited within the scope of the appended claims.

[0040] The shapes, sizes, proportions, angles, quantities, etc. shown in the drawings for describing the embodiments of the present invention are merely examples, and the present invention is not limited thereto. Throughout this specification, similar reference numerals generally refer to similar elements. In addition, when describing the present invention, detailed descriptions of related known technologies may be omitted to avoid unnecessarily obscuring the subject matter of the present invention.

[0041] Terms such as “including,” “having,” and “comprising” used herein are generally intended to allow the addition of other components unless these terms are used with the term “only.” Singular references will be construed to include the plural unless explicitly stated otherwise.

[0042] When interpreting the elements, they are interpreted as including the margin of error even if not explicitly stated.

[0043] When using terms such as "on", "upper", "lower", "after", "connected or joined", "crossing", "intersecting", etc. to describe the positional relationship or interconnection relationship between two components, one or more other components may be inserted between the two components unless "immediately" or "directly" is used.

[0044] When terms such as "after", "subsequently", "next", or "before" are used to describe a temporal context, there may be no continuity in the time scale unless "immediately" or "directly" is used.

[0045] The first, second, etc. can be used before the element name to distinguish the element, but its function or structure is not limited by these ordinal numbers or element names. For ease of description, the ordinal numbers placed before the same element name may be different between embodiments.

[0046] The following embodiments may be combined or associated with each other in whole or in part, and various interlocks and drives are technically possible. The embodiments may be implemented independently of each other, or implemented together in an interrelated relationship.

[0047] Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0048] Figure 1 is a diagram schematically illustrating a display device according to an embodiment of the present invention. Figure 2 yes Figure 1 Magnified view of area A in FIG. Figure 3 is a diagram showing a local area of ​​a pixel.

[0049] Reference Figure 1 and 2 According to one embodiment of the present invention, a display device 100 includes a display panel on which an input image is visually reproduced. The display panel may include a display area AA in which an image is displayed and a non-display area NA in which an image is not displayed. In the non-display area NA, various wires and driving circuits may be installed, and a pad portion PAD may be provided to connect an integrated circuit, a printed circuit, etc.

[0050] The plurality of light emitting elements 10 disposed in the display area AA to form the pixel PXL may be micro-sized inorganic light emitting elements. The inorganic light emitting elements may be grown on a silicon wafer and then attached to the display panel via a transfer process.

[0051] The transfer process of the light emitting element 10 may be performed for each pre-divided region. Figure 1, the display area AA is shown as being divided into 12 transfer areas ST, but the division size or number of the transfer areas is not limited thereto. The transfer process may be performed sequentially or simultaneously for the first to twelfth transfer areas ST. The blue light emitting element 10, the green light emitting element 10, and the red light emitting element 10 may be sequentially transferred to the transfer area ST.

[0052] In the non-display area NA, a data driving circuit or a gate driving circuit may be provided, and a wire may be provided to provide a control signal for controlling the driving circuit. Here, the control signal may include various timing signals including a clock signal, an input data enable signal, and a synchronization signal, and may be received via the pad portion PAD.

[0053] The pixel PXL can be driven by a pixel driving circuit. The pixel driving circuit can receive a driving voltage, an image signal (digital signal), a synchronization signal synchronized with the image signal, etc., and output an anode voltage and a cathode voltage of the light-emitting element 10 to drive a plurality of pixels. The driving voltage can be a high potential voltage EVDD. The cathode voltage can be a low potential voltage EVSS commonly applied to the pixel. The anode voltage can be a voltage corresponding to the pixel data value of the image signal. The pixel driving circuit can be arranged in the non-display area NA, or can be arranged below the display area AA.

[0054] Each pixel PXL may include a plurality of sub-pixels having different colors. For example, the plurality of sub-pixels may include: a red sub-pixel in which a light-emitting element 10 emitting light of a red wavelength is disposed; a green sub-pixel in which a light-emitting element 10 emitting light of a green wavelength is disposed; and a blue sub-pixel in which a light-emitting element 10 emitting light of a blue wavelength is disposed. The plurality of sub-pixels may further include a white sub-pixel.

[0055] Reference Figure 2 and 3, a plurality of pixels PXL may be continuously arranged in a first direction (X-axis direction) and a second direction (Y-axis direction). A plurality of sub-pixels of the same color may be arranged in a pixel of the display area AA. For example, each of the plurality of pixels may include: a first red sub-pixel, in which a 1-1 light-emitting element 11a emitting light of a red wavelength is arranged; a second red sub-pixel, in which a 1-2 light-emitting element 11b emitting light of a red wavelength is arranged; a first green sub-pixel, in which a 2-1 light-emitting element 12a emitting light of a green wavelength is arranged; a second green sub-pixel, in which a 2-2 light-emitting element 12b emitting light of a green wavelength is arranged; a first blue sub-pixel, in which a 3-1 light-emitting element 13a emitting light of a blue wavelength is arranged; and a second blue sub-pixel, in which a 3-2 light-emitting element 13b emitting light of a blue wavelength is arranged. The 1-1 light-emitting element 11a, the 2-1 light-emitting element 12a, and the 3-1 light-emitting element 13a emitting light of a blue wavelength may be regarded as main light-emitting elements. The 1-2nd light emitting element 11b, the 2-2nd light emitting element 12b, and the 3-2nd light emitting element 13b can be regarded as auxiliary light emitting elements.

[0056] One subpixel may include at least one or more light emitting elements, and if one light emitting element becomes defective, the brightness of another light emitting element may increase to adjust the brightness of the subpixel. However, the present invention is not necessarily limited thereto, and one subpixel may include only one light emitting element.

[0057] Each of the plurality of first electrodes 161 may be disposed below the light emitting element 10 and may be selectively connected to the plurality of signal lines TL1 to TL6 through the extension 161a. A high potential voltage may be applied to the pixel driving circuit via the signal lines TL1 to TL6. The signal lines TL1 to TL6 and the first electrodes 161 may be formed as an electrode pattern integrally formed with the anode during the electrode patterning process.

[0058] For example, the first signal line TL1 may be connected to the anode of the first red sub-pixel, and the second signal line TL2 may be connected to the anode of the second red sub-pixel. The third signal line TL3 may be connected to the anode of the first green sub-pixel, and the fourth signal line TL4 may be connected to the anode of the second green sub-pixel. The fifth signal line TL5 may be connected to the anode of the first blue sub-pixel, and the sixth signal line TL6 may be connected to the anode of the second blue sub-pixel. When one sub-pixel includes only one light-emitting element, the number of signal lines TL may be reduced by half.

[0059] The second electrode 170 may be a cathode that is provided one for each row and applies a cathode voltage to the light emitting elements 10 that are continuously arranged in the first direction (X-axis direction). A plurality of second electrodes 170 may be spaced apart from each other in the second direction (Y-axis direction). A plurality of second electrodes 170 may be connected to the cathode voltage via the contact electrode 163. Each of the plurality of second electrodes 170 may be electrically connected to the contact electrode 163. However, the present invention is not necessarily limited thereto, and the second electrode 170 may be configured as one electrode layer without being divided into a plurality of electrodes, and may be used as a common electrode.

[0060] Figure 4 is along Figure 3 A cross-sectional view taken along line IV-IV'. Figure 5 is along Figure 3 A cross-sectional view taken along line V-V'.

[0061] Reference Figure 4 and 5 A display device having a plurality of light-emitting elements transferred by a stamp for transferring light-emitting elements according to an embodiment includes: a plurality of first electrodes 161 and a contact electrode 163 arranged above a transfer substrate 110; a plurality of light-emitting elements 10 arranged on the plurality of first electrodes 161; an optical layer 141 arranged between the plurality of light-emitting elements 10; and a second electrode 170 arranged on the plurality of light-emitting elements 10.

[0062] The transfer substrate 110 may be made of flexible plastic. For example, the substrate 110 may be manufactured as a single-layer or multi-layer substrate 110 composed of a material selected from polyimide, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyether sulfone, polyacrylate, polysulfone, and cyclic olefin copolymer (but not limited thereto). For example, the transfer substrate 110 may be a ceramic substrate or a glass substrate.

[0063] The pixel driving circuit 20 may be disposed in the display area AA on the transfer substrate 110. The pixel driving circuit 20 may include a plurality of thin film transistors using an amorphous silicon semiconductor, a polysilicon semiconductor, or an oxide semiconductor.

[0064] The pixel driving circuit 20 may include at least one driving thin film transistor, at least one switching thin film transistor, and at least one storage capacitor. When the pixel driving circuit 20 includes a plurality of thin film transistors, it may be formed on the transfer substrate 110 by a TFT (thin film transistor) manufacturing process. In an embodiment, the pixel driving circuit 20 may be a general term for a plurality of thin film transistors electrically connected to the light emitting element 10.

[0065] The pixel driving circuit 20 may be a driving driver manufactured using a metal oxide semiconductor field effect transistor (MOSFET) manufacturing process on a transfer substrate 110 that is a single crystal semiconductor substrate. The driving driver may include a plurality of pixel driving circuits that drive a plurality of sub-pixels. When the pixel driving circuit 20 is implemented as a driving driver, an adhesive layer may be provided on the transfer substrate 110, and then the driving driver may be mounted on the adhesive layer through a transfer process.

[0066] A first insulating layer 121 covering the pixel driving circuit 20 may be disposed on the transfer substrate 110. The first insulating layer 121 may be made of an organic insulating material, for example, photo acryl or photo polyimide, but is not limited thereto.

[0067] The first insulating layer 121 may be formed by stacking an inorganic insulating material such as silicon nitride (SiNx) or silicon oxide (SiO 2 ) or by stacking an organic insulating material or an inorganic insulating material in multiple layers.

[0068] The second insulating layer 122 may be disposed on the first insulating layer 121. The second insulating layer 122 may be made of an organic insulating material such as photosensitive optical acryl or photosensitive polyimide, but is not limited thereto. The connecting wires RT1 and RT2 may be disposed on the first insulating layer 121. The connecting wires RT1 and RT2 may be connected to the corresponding signal lines TL1 to TL6 or may be connected to the signal lines TL1 to TL6. The connecting wires RT1 and RT2 may include a plurality of wire patterns disposed in different layers with one or more insulating layers interposed therebetween. The wire patterns disposed in different layers may be electrically connected via contact holes penetrating the insulating layers.

[0069] A plurality of bank patterns 130 may be disposed on the second insulating layer 122. At least one light emitting element 10 may be disposed above each bank pattern 130. For example, a first light emitting element 11 may be disposed on the first bank pattern 130, a second light emitting element 12 may be disposed on the second bank pattern 130, and a third light emitting element 13 may be disposed on the third bank pattern 130.

[0070] The bank pattern 130 may be formed of an organic insulating material such as photosensitive optical acryl or photosensitive polyimide, but is not limited thereto. The bank pattern 130 may guide a position to which the light emitting element 10 is attached during a transfer process of the light emitting element 10. The bank pattern 130 may be omitted.

[0071] A solder pattern 162 may be disposed on the first electrode 161. The solder pattern 162 may be made of indium (In), tin (Sn), or an alloy thereof, but is not limited thereto.

[0072] A plurality of light emitting elements 10 may be mounted on the corresponding solder patterns 162. One pixel may include three colors of light emitting elements 10. The first light emitting element 11 may be a red light emitting element, the second light emitting element 12 may be a green light emitting element, and the third light emitting element 13 may be a blue light emitting element. Two light emitting elements may be mounted in each sub-pixel.

[0073] The optical layer 141 may cover the plurality of light emitting elements 10 and the plurality of dam patterns 130. Thus, the optical layer 141 may cover between the plurality of light emitting elements 10 and between the plurality of dam patterns 130. The optical layer 141 may extend in the first direction X, and may be spaced apart in the second direction Y and separated between pixel rows.

[0074] The optical layer 141 may include an organic insulating material in which fine metal particles such as titanium dioxide particles are dispersed. Light emitted from the plurality of light emitting elements 10 may be diffused by the fine metal particles dispersed in the optical layer 141 and emitted to the outside.

[0075] The second electrode 170 may be disposed on the plurality of light emitting elements 10. The second electrode 170 may be commonly connected to the plurality of pixels PXL. The second electrode 170 may be a thin electrode for transmitting light. The second electrode 170 may be made of a transparent electrode material such as indium tin oxide (ITO), but is not necessarily limited thereto.

[0076] The second electrode 170 may extend in the first direction X and may be spaced apart in the second direction Y. The second electrode 170 is disposed on the top surface of the light emitting element 10 and the top surface of the optical layer 141 and may make contact with the contact electrode 163 .

[0077] According to an embodiment, the second electrode 170 is connected to the contact electrode while being formed flatly as a whole, and thus excessive stress is not concentrated at a point connected to the contact electrode 163. Therefore, cracks occurring in the second electrode 170 may be effectively prevented.

[0078] The black matrix 180 may be an organic insulating material to which a black pigment is added. The second electrode 170 may be in contact with the contact electrode 163 below the black matrix 180. The transmissive hole 154 may be formed between the patterns of the black matrix 180, and the light emitted from the light emitting element 10 is emitted to the outside through the transmissive hole 154. The problem of mixing of light emitted from adjacent light emitting elements 10 due to the optical layer 141 may be improved by the black matrix 180.

[0079] The capping layer 190 may be an organic insulating material covering the black matrix 180 and the second electrode 170 .

[0080] The contact electrode 163 may be electrically connected to a first connection line RT1 disposed thereunder, and the first connection line RT1 may be connected to the pixel driving circuit 20 .

[0081] Therefore, the cathode voltage may be applied to the second electrode 170 via the contact electrode 163. The first electrode 161 may be electrically connected to the second connection line RT2. This will be described later.

[0082] The contact electrode 163 and the signal lines TL1 to TL6 may be disposed on the same plane. The pixel driving circuit 20 may be disposed below the contact electrode 163 and the signal lines TL1 to TL6. When the pixel driving circuit 20 is a driving driver, a plurality of driving drivers may be disposed in the display panel.

[0083] The third insulating layer 133 may expose the contact electrode 163 so that the contact electrode 163 and the second electrode 170 are electrically connected to each other. In addition, the third insulating layer 133 may insulate the signal lines TL2 to TL5 from the second electrode 170 .

[0084] The first electrode 161, the signal line TL and / or the connection line RT2 may include a single layer or multiple layers of a metal selected from titanium (Ti), molybdenum (Mo) and aluminum (Al). The first electrode 161, the signal line TL and / or the connection line RT2 may be formed in a multi-layer structure.

[0085] Reference Figure 5 The light emitting element (hereinafter referred to as LED) 10 is a semiconductor element that emits light energy of various wavelengths by applying an electrical signal using the characteristics of a compound semiconductor. The light emitting element 10 may be configured to have a thickness as small as several micrometers.

[0086] The light emitting element 10 may include a first conductive type semiconductor layer 10-1, an active layer 10-2 disposed on the first conductive type semiconductor layer 10-1, and a second conductive type semiconductor layer 10-3 disposed on the active layer 10-2. The first driving electrode 15 may be disposed below the first conductive type semiconductor layer 10-1, and the second driving electrode 14 may be disposed on an upper portion of the second conductive type semiconductor layer 10-3.

[0087] The light emitting element 10 can be formed on a silicon wafer by using a method such as metal organic chemical vapor deposition (MOCVD), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), molecular beam epitaxy (MBE), hydride vapor phase epitaxy (HVPE) or sputtering.

[0088] The first conductive type semiconductor layer 10-1 may be implemented using a compound semiconductor such as a group III-V or group II-VI semiconductor, and may be doped with a first dopant. The first conductive type semiconductor layer 10-1 may be made of a compound semiconductor having an empirical formula of Al x1 In y1 Ga (1-x1-y1)The first conductive type semiconductor layer 10-1 may be formed of one or more of the following semiconductor materials N (0≤x1≤1,0≤y1≤1,0≤x1+y1≤1): InAlGaN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP, but is not limited thereto. When the first dopant is an n-type dopant such as Si, Ge, Sn, Se, or Te, the first conductive type semiconductor layer 10-1 may be an n-type nitride semiconductor layer. However, when the first dopant is a p-type dopant, the first conductive type semiconductor layer 10-1 may be a p-type nitride semiconductor layer.

[0089] The active layer 10-2 is a layer where electrons (or holes) injected via the first conductive type semiconductor layer 10-1 and holes (or electrons) injected via the second conductive type semiconductor layer 10-3 meet. The active layer 10-2 may transition to a low energy level when the electrons and holes recombine, and may generate light having a corresponding wavelength.

[0090] The active layer 10-2 may have any one structure selected from a single well structure, a multi-well structure, a single quantum well structure, a multi-quantum well (MQW) structure, a quantum dot structure, and a quantum wire structure, but the structure of the active layer 10-2 is not limited thereto. The active layer 10-2 may generate light of a visible wavelength band. For example, the active layer 10-2 may output light of any one wavelength band of a blue wavelength band, a green wavelength band, and a red wavelength band.

[0091] The second conductive type semiconductor layer 10-3 may be disposed on the active layer 10-2. The second conductive type semiconductor layer 10-3 may be implemented using a compound semiconductor such as a group III-V or group II-VI semiconductor, and may be doped with a second dopant. The second conductive type semiconductor layer 10-3 may be made of a semiconductor having an experimental formula of In x2 Al y2 Ga 1-x2-y2 N (0≤x2≤1,0≤y2≤1,0≤x2+y2≤1) semiconductor material, or is formed of a material selected from AlInN, AlGaAs, GaP, GaAs, GaAsP, AlGaInP and AlGaInP. When the second dopant is a p-type dopant such as Mg, Zn, Ca, Sr or Ba, the second conductive type semiconductor layer 10-3 doped with the second dopant may be a p-type nitride semiconductor layer. When the second dopant is an n-type dopant, the second conductive type semiconductor layer 10-3 may be an n-type nitride semiconductor layer.

[0092] The reflective layer 16 may be formed on the side and lower part of the light emitting element 10. The reflective layer 16 may have a structure in which a reflective material is dispersed in a resin layer, but is not necessarily limited thereto. As an example, the reflective layer 16 may be manufactured using reflectors of various structures. The light emitted from the active layer 10-2 may be reflected upward by the reflective layer 16 to increase light extraction efficiency.

[0093] Although the light emitting element is described as having a vertical structure in which the driving electrodes 14 and 15 are disposed above and below the light emitting structure in the embodiment, the light emitting element may have a lateral or transverse structure or a flip chip structure in addition to the vertical structure.

[0094] In the following, reference will be made to Figures 6A to 6C A process of picking up a plurality of light emitting elements constituting a display device from a growth substrate and transferring the plurality of light emitting elements to a transfer substrate using a light emitting element transfer stamp according to one embodiment of the present invention is schematically described.

[0095] Figures 6A to 6C is a perspective view schematically illustrating a state in which a light emitting element is transferred onto a transfer substrate using a light emitting element transfer stamp according to one embodiment of the present invention.

[0096] Reference Fig. 6A In order to transfer a plurality of light-emitting elements constituting a display device, a growth substrate 310 on which a plurality of light-emitting elements 10 are arranged, a light-emitting element transfer stamp 200 for picking up and placing the plurality of light-emitting elements 10, and a transfer substrate 110 on which the plurality of light-emitting elements 10 are transferred to constitute a display device can be provided.

[0097] The growth substrate 310 may be used as a base substrate for growing the light emitting element 10 as an LED chip, and may be made of a material selected from silicon (Si), sapphire (Al 2 O 3 ), silicon carbide (SiC), gallium arsenide (GaAs), gallium nitride (GaN), gallium phosphide (GaP), indium phosphide (InP), zinc oxide (ZnO), spinel (MgAl 2 O 4 ), magnesium oxide (MgO), lithium aluminate (LiAlO 2 ), aluminum nitride (AlN), and lithium gallium oxide (LiGaO 2 ) is made of any material, but not limited to this.

[0098] A plurality of micro light-emitting elements 10 may be grown on the growth substrate 310 .

[0099] The light emitting element 10 is a semiconductor device that emits light energy of various wavelengths by applying an electrical signal using the characteristics of a compound semiconductor. The light emitting element 10 can be provided with a thickness as small as several micrometers.

[0100] A plurality of light emitting elements 10 are arranged side by side in one direction on the growth substrate 310. The spacing G between adjacent light emitting elements 10 is set to have the minimum distance possible in the process. That is, in order to reduce the manufacturing cost of the growth substrate 310, a large number of light emitting elements 10 need to be integrated into a smaller growth substrate 310.

[0101] The light emitting element transfer stamp 200 is used as a transfer device for transferring a plurality of light emitting elements 10 from the growth substrate 310 to the transfer substrate 110. The light emitting element transfer stamp 200 selectively picks up the light emitting elements 10 from the growth substrate 310. The light emitting element transfer stamp 200 selectively picks up only the light emitting element 10 at a predetermined position and transfers it to each corresponding pixel on the transfer substrate 110.

[0102] The transfer substrate 110 is a substrate constituting a display device, and has a plurality of pixels arranged thereon. The region in which the plurality of pixels are arranged may be defined as an active region. At least one light emitting element 10 is ultimately assigned to each of the plurality of pixels. Signal lines and electrodes for applying a drive signal to the light emitting element 10 may be arranged on the transfer substrate 110. When implemented in an AM (active matrix) method, the transfer substrate 110 may further include a thin film transistor assigned to each pixel.

[0103] Reference Figure 6B and 6C The light emitting elements 10 transferred to adjacent pixels are arranged at a predetermined pitch P1. The pitch P1 between adjacent light emitting elements 10 among the light emitting elements 10 transferred onto the transfer substrate 110 may be appropriately selected in consideration of display characteristics, element arrangement, and the like.

[0104] The transfer substrate 110 may be provided to have a size relatively greater than that of the light emitting element transfer stamp 200 .

[0105] More specifically, the active region of the transfer substrate 110 may be configured to have an area greater than that of the light emitting element transfer stamp 200. In this case, in order to transfer the light emitting element 10 to all pixels arranged in the active region, as shown in FIG. Figure 6B and 6C As shown, it is necessary to repeat a plurality of pick-up / transfer operations corresponding to the area difference between the active region and the light emitting element transfer stamp 200 .

[0106] Hereinafter, the structure of a light emitting element transfer stamp for transferring a plurality of light emitting elements constituting a display device onto a transfer substrate according to the present invention will be described in detail.

[0107] Figure 7 is a plan view illustrating a light emitting element transfer stamp for a display device according to an embodiment of the present invention. Figure 8is along Figure 7 A cross-sectional view taken along line VIII-VIII'.

[0108] Reference Figure 7 and 8 The light emitting element transfer stamp 200 for a display device according to the present invention comprises: a stamp substrate 210; a plurality of insertion grooves 220 formed at regular intervals in the stamp substrate 210; and a plurality of substrates 220 and 220 respectively arranged in the insertion grooves 220 and on the stamp substrate 210 in contact with the insertion grooves 220 to adhere to and grow on a growth substrate (not shown, see Fig. 6A a plurality of adhesive layers 230 for forming a light emitting element 10 on the mold substrate 310); a passivation layer 250 disposed on the exposed top surface of the mold substrate 210 and on the exposed side surfaces of the adhesive layer 230, the passivation layer 250 being disposed on the mold substrate 210 between the plurality of adhesive layers 230; and a buffer layer 280 disposed on the rear surface of the mold substrate 210 to improve heat application and leveling effect.

[0109] The stamp substrate 210 may be used as a substrate for transferring the light emitting element 10 from a growth substrate (not shown, see Fig. 6A 310) is transferred to a transfer substrate (not shown, see Figure 6B 110) transfer device.

[0110] A quartz substrate, a sapphire substrate, or a silicon substrate may be used as the stamp substrate 210. However, the present invention is not necessarily limited thereto.

[0111] The insertion groove 220 can be used to suppress the left-right movement of the adhesive layer 230 made of a viscoelastic material due to the contraction and expansion caused by thermal deformation. In particular, when heat is applied to the buffer layer 280 provided on the rear surface of the stamp substrate 210 (heating is turned on), the insertion groove 220 is used to suppress the risk that may occur due to the contraction and expansion of the side surface of the adhesive layer 230 made of a viscoelastic material, that is, the misalignment caused by the lateral position change of the adhesive layer 230.

[0112] The insertion groove 220 may have a width w ranging from 1 μm to 1000 μm, and a depth d ranging from 0.1 μm to 500 μm, but is not necessarily limited thereto. The insertion groove 220 may have a quadrilateral, circular, or polygonal shape, but is not necessarily limited thereto.

[0113] The adhesive layer 230 may include: a support portion 232 inserted and fixed in the insertion groove 220; and a pick-up portion 234 formed as one body with the support portion 232 and disposed to protrude above the insertion groove 220 and above the top surface of the stamp substrate 210 located above the side surface of the insertion groove 220 to pick up the growth substrate (not shown, see Fig. 6A 310) on the light emitting element (not shown, see Fig. 6A 10). The adhesive layer 230 may extend within the insertion groove 220 and on the stamp substrate 210 located above the side surface of the insertion groove to protrude above the stamp substrate 210.

[0114] The adhesive layer 230 is used to pick up the light emitting element by utilizing the surface adhesive property of the material thereof, and the application of the flexible viscoelastic material allows picking up light emitting elements of various shapes, structures and sizes without requiring a complex spring structure as in conventional technology.

[0115] The pick-up portion 234 of the adhesive layer 230 may have a quadrilateral, a circular, or a polygonal shape, but is not necessarily limited thereto.

[0116] The material of the adhesive layer 230 may include PDMS, PAC, urethane, acrylic or epoxy materials. However, it is not necessarily limited thereto. There is no limitation on the thickness of the adhesive layer 230.

[0117] Since the support portion 232 of the adhesive layer 230 is inserted and supported within the insertion groove 220 , lateral contraction / expansion of the adhesive layer 230 may be suppressed by the insertion groove 220 , thereby increasing positional accuracy.

[0118] Due to the heat applied from the rear surface of the stamp substrate 210, the viscoelastic material of the adhesive layer 230 may undergo thermal expansion and deformation, causing the surface shape of the picking portion 234 of the adhesive layer 230 to become a convex shape protruding in the vertical direction of the stamp substrate 210, specifically, a rounded shape, which is conducive to picking up the light-emitting element.

[0119] The passivation layer 250 is used to suppress thermal expansion and deformation of the adhesive layer 230 in the lateral direction, and to guide thermal expansion through the upper exposure of the pickup portion 234 of the adhesive layer 230. The passivation layer 250 may be made of a material containing Al. 2 O 3 The passivation layer 250 may be made of at least one of an inorganic film material having a low thermal expansion coefficient and an inorganic film material such as ceramic. However, it is not necessarily limited thereto. The thickness of the passivation layer 250 is not limited.

[0120] When heat is applied to the stamp substrate 210 , the viscoelastic material of the adhesive layer 230 may thermally expand and deform to be exposed upward, causing the surface shape of the pickup portion 234 of the adhesive layer 230 to change into a shape that facilitates picking up the light emitting element.

[0121] The buffer layer 280 is a layer for transferring heat to the viscoelastic material, and for further enhancing or weakening the surface adhesive properties of the viscoelastic material according to the heat applied. Typically, the adhesive properties allow the light emitting element to be picked up even at room temperature, but as the surface of the material degrades through contact with air, a situation where the surface adhesive properties are weakened may occur.

[0122] In this case, the buffer layer 280 can be used to enhance surface adhesion characteristics and improve pickup yield by applying heat within an appropriate temperature range to the buffer layer 280. In addition, the buffer layer 280 improves the balancing effect during pickup / placement of the light emitting element, which is beneficial to face-to-face adhesion balance.

[0123] The buffer layer 280 may be made of a thermally conductive resin material, a thermally conductive polymer material, a thermally conductive metal material, or the like.

[0124] As the thermally conductive resin material, a material obtained by adding graphite, Al, etc. to a resin material may be used. The thermally conductive resin material used as the material of the buffer layer 280 is not limited, and the thickness of the buffer layer 280 is also not limited.

[0125] The thermally conductive polymer material may include at least one of polyethylene, polycarbonate, polyamide / polyimide, polybenzimidazole, ethylene-tetrafluoroethylene copolymer, polyacrylonitrile-butadiene-styrene, and other thermally conductive materials. However, it is not necessarily limited thereto. For example, the thermally conductive polymer material may have a thermal conductivity ranging from 5×10-1 to 1×10 2 Thermal conductivity (Wm -1 K -1 ). However, it is not necessarily limited thereto.

[0126] As the thermally conductive metal material, metals such as Al, Zn, Au, Pt, V, and Ni or alloys thereof may be used. The thermally conductive metal material may have a thermal conductivity ranging from 1×101 to 1×10 3 Thermal conductivity (Wm -1 K -1 ). However, it is not necessarily limited thereto.

[0127] In particular, when heat is applied to the buffer layer 280 in an appropriate temperature range, for example, from 30° C. to 250° C., the surface adhesive property of the adhesive layer 230 may be enhanced, thereby improving a pickup yield. The temperature range for applying heat to the buffer layer 280 is not limited thereto.

[0128] Furthermore, when picking up via the adhesive layer 230 , applying heat to the buffer layer 280 may produce favorable characteristics for picking up due to surface expansion of the viscoelastic material of the adhesive layer 230 .

[0129] When the transfer substrate (not shown, see Figure 6B When placing the light emitting element 10 on the transfer substrate 110, the temperature is lowered by stopping the heat application (heating off) so that the heat-expanded adhesive layer 230 contracts, thereby reducing the contact area between the adhesive layer 230 and the light emitting element 10, thereby reducing the adhesive force. As a result, the light emitting element 10 can be easily placed on the transfer substrate 110 from the adhesive layer 230.

[0130] An apparatus head for bonding the light emitting element transfer stamp 200 is not limited to means such as a vacuum head, an electrostatic head, or the like.

[0131] According to the present invention, the light-emitting element transfer stamp 200 has predetermined adhesion (or adsorption) characteristics, so that the light-emitting element 10 set at a predetermined position can be selectively extracted from the growth substrate 310 by adhesion force, and when the adhesion force is released, the light-emitting element 10 can be transferred to the corresponding pixel of the transfer substrate 110.

[0132] The adhesive force of the adhesive layer 230 may be released by using heat or chemical properties. For example, a release layer may be provided between the stamp substrate 210 and the light emitting element 10, and the adhesive force may be released by irradiating the release layer with laser.

[0133] The reason for using the light emitting element transfer stamp 200 to selectively pick up the light emitting element 10 is that the spacing between the light emitting elements 10 grown on the growth substrate 310 (not shown, see Fig. 6A G) and the required spacing between the light emitting elements 10 transferred to the transfer substrate 110 (not shown, see Figure 6B Therefore, the pitch between adjacent light-emitting elements 10 among the light-emitting elements 10 simultaneously extracted by the light-emitting element transfer stamp 200 finally corresponds to the pitch between the light-emitting elements 10 transferred to the pixel.

[0134] In the following, reference will be made to Figures 9A to 9J A method for manufacturing a light emitting element transfer stamp for a display device according to one embodiment of the present invention is described.

[0135] Figures 9A to 9J is a cross-sectional view illustrating a manufacturing process of a light emitting element transfer stamp for a display device according to an embodiment of the present invention.

[0136] Reference Fig. 9A and 9B, a stamp substrate 210 is prepared, and a mask process is performed on the stamp substrate 210 using a photolithography technique to form a plurality of insertion grooves 220 having a certain depth at regular intervals in the stamp substrate 210 .

[0137] The stamp substrate 210 may be used as a substrate for transferring the light emitting element 10 from a growth substrate (not shown, see Fig. 6A 310) is transferred to a transfer substrate (not shown, see Figure 6B 110) transfer device.

[0138] A quartz substrate, a sapphire substrate, or a silicon substrate may be used as the stamp substrate 210. However, the present invention is not necessarily limited thereto.

[0139] The insertion groove 220 can be used to suppress the left-right movement of the adhesive layer 230 made of a viscoelastic material due to the contraction and expansion caused by thermal deformation. In particular, when heat is applied to the buffer layer 280 provided on the rear surface of the stamp substrate 210 (heating is turned on), the insertion groove 220 is used to suppress the risk that may occur due to the contraction and expansion of the side surface of the adhesive layer 230 made of a viscoelastic material, that is, the misalignment caused by the lateral position change of the adhesive layer 230.

[0140] The insertion groove 220 may have a width w ranging from 1 μm to 1000 μm, and a depth d ranging from 0.1 μm to 500 μm, but is not necessarily limited thereto.

[0141] The insertion groove 220 may have a quadrilateral, a circular, or a polygonal shape, but is not necessarily limited thereto.

[0142] Next, refer to Fig. 9C , an adhesive material layer 230 a for forming an adhesive layer is formed on the stamp substrate 210 including the insertion groove 220 .

[0143] The material of the adhesive material layer 230a may include PDMS, PAC, urethane, acrylic or epoxy materials. However, it is not necessarily limited thereto. There is no limitation on the thickness of the adhesive material layer 230a.

[0144] Then, refer to Fig.9D , a first photosensitive film (not shown) is coated on the adhesive material layer 230a, and a mask process is performed using a photolithography technique to form a first photosensitive film pattern 240 that remains only on the top of the adhesive material layer 230a for defining an adhesive layer region.

[0145] Then, refer to Fig.9E , the adhesive material layer 230 a is selectively patterned using the first photosensitive film pattern 240 as a mask to form the adhesive layer 230 , and the remaining first photosensitive film pattern 240 is removed.

[0146] The adhesive layer 230 may include: a support portion 232 inserted and fixed in the insertion groove 220; and a pick-up portion 234 formed as one body with the support portion 232 and disposed to protrude above the insertion groove 220 and above the top surface of the stamp substrate 210 located above the side surface of the insertion groove 220 to pick up the growth substrate (not shown, see Fig. 6A 310) on the light emitting element (not shown, see Fig. 6A 10).

[0147] The adhesive layer 230 is used to pick up the light emitting element by utilizing the surface adhesive property of the material thereof, and the application of the flexible viscoelastic material allows picking up light emitting elements of various shapes, structures and sizes without requiring a complex spring structure as in conventional technology.

[0148] The pick-up portion 234 of the adhesive layer 230 may have a quadrilateral, a circular, or a polygonal shape, but is not necessarily limited thereto.

[0149] Since the support portion 232 of the adhesive layer 230 is inserted and supported within the insertion groove 220 , lateral contraction / expansion of the adhesive layer 230 may be suppressed by the insertion groove 220 , thereby increasing positional accuracy.

[0150] Due to the heat applied from the rear surface of the stamp substrate 210, the viscoelastic material of the adhesive layer 230 may undergo thermal expansion and deformation, causing the surface shape of the pickup portion 234 of the adhesive layer 230 to become a convex shape protruding in the vertical direction of the stamp substrate 210, specifically, a rounded shape, which is conducive to picking up the light-emitting element.

[0151] Next, refer to Fig.9F , a passivation layer 250 is deposited on the entire surface of the stamp substrate 210 and the adhesive layer 230 , and a second photosensitive film 260 is coated on the passivation layer 250 .

[0152] The passivation layer 250 may be made of Al 2 O 3 The passivation layer 250 may be made of an inorganic film material having a low thermal expansion coefficient or an inorganic film material such as ceramic. However, it is not necessarily limited thereto. The thickness of the passivation layer 250 is not limited.

[0153] Then, refer to Figure 9G , the second photosensitive film 260 is etched by performing a mask process using a photolithography technique until a portion of the passivation layer 250 covering the top surface of the adhesive layer 230 is exposed.

[0154] Then, refer to Figure 9H , using the selectively etched second photosensitive film 260 as a mask, the exposed portion of the passivation layer 250 covering the adhesive layer 230 is etched to expose the top surface of the adhesive layer 230 .

[0155] That is, the top surface of the pickup portion 234 of the adhesive layer 230 is exposed to the outside. In addition, the passivation layer 250 remains on the side surface of the adhesive layer 230 and the exposed top surface of the stamp substrate 210 .

[0156] The passivation layer 250 serves to suppress thermal expansion and deformation of the adhesive layer 230 in a lateral direction, and serves to guide thermal expansion and deformation of an upper portion of the pickup portion 234 of the adhesive layer 230 in a vertical direction of the stamp substrate 210 .

[0157] Next, refer to Fig.9I , when the stamp substrate 210 is in an inverted (ie, reversed) state, before a buffer layer is formed on a rear surface of the stamp substrate 210 (which will be described later), a third photosensitive film 270 is applied to the passivation layer 250 and the adhesive layer 230 .

[0158] The third photosensitive film 270 may be used to protect the surface of the pickup portion 234 of the adhesive layer 230 from scratches or other contaminants during a process of forming a buffer layer on the rear surface of the stamp substrate 210 while the stamp substrate 210 is in an inverted (ie, reversed) state.

[0159] Subsequently, a buffer layer 280 is formed on the rear surface of the stamp substrate 210 to improve heat application and balancing effects when the stamp substrate 210 is in an inverted state.

[0160] The buffer layer 280 is a layer for transferring heat to the viscoelastic material, and for further enhancing or weakening the surface adhesive properties of the viscoelastic material according to the heat applied. Typically, the adhesive properties allow the light emitting element to be picked up even at room temperature, but as the surface of the material degrades through contact with air, a situation where the surface adhesive properties are weakened may occur.

[0161] The buffer layer 280 may be made of a thermally conductive resin material, a thermally conductive polymer material, a thermally conductive metal material, or the like.

[0162] As the thermally conductive resin material, a material obtained by adding graphite, Al, etc. to a resin material may be used. The thermally conductive resin material used as the material of the buffer layer 280 is not limited, and the thickness of the buffer layer 280 is also not limited.

[0163] The use of thermally conductive resin can improve the balance of the transfer process at the time of pick / place of the light emitting element.

[0164] The thermally conductive polymer material may include polyethylene, polycarbonate, polyamide / polyimide, polybenzimidazole, ethylene-tetrafluoroethylene copolymer, polyacrylonitrile-butadiene-styrene, and other thermally conductive materials. However, it is not necessarily limited thereto. For example, the thermally conductive polymer material may have a thermal conductivity ranging from 5×10-1 to 1×10 2Thermal conductivity (Wm -1 K -1 ). However, it is not necessarily limited thereto.

[0165] As the thermally conductive metal material, metals such as Al, Zn, Au, Pt, V, and Ni or alloys thereof may be used. The thermally conductive metal material may have a thermal conductivity ranging from 1×101 to 1×10 3 Thermal conductivity (Wm -1 K -1 ). However, it is not necessarily limited thereto.

[0166] When heat is applied to the buffer layer 280 in an appropriate temperature range, for example, a temperature range from 30° C. to 250° C., the surface adhesive property may be enhanced, thereby improving a pickup yield.

[0167] Next, refer to Figure 9J When the stamp substrate 210 is in the inverted state again, the third photosensitive film 270 is removed, thereby completing the manufacturing process of the light emitting element transfer stamp 200 for a display device according to the present invention.

[0168] In the following, reference will be made to Figures 10A to 10G A process of picking up and transferring a light emitting element using the light emitting element transfer stamp for a display device according to the present invention is described.

[0169] Figures 10A to 10G is a cross-sectional view illustrating a process of transferring a light emitting element onto a transfer substrate using a light emitting element transfer stamp for a display device according to an embodiment of the present invention.

[0170] Reference Fig. 10A After manufacturing the light emitting element transfer stamp 200 , if heat is not applied to the buffer layer 280 disposed on the rear surface of the stamp substrate 210 (no heating), the surface viscosity of the adhesive layer 230 is weakened.

[0171] Reference Fig. 10B By applying heat to the buffer layer 280 disposed on the rear surface of the stamp substrate 210 (heat-on), the surface adhesiveness of the adhesive layer 230, that is, the pickup portion 234 can be improved by low-temperature heat application (heat-on).

[0172] Reference Fig. 10C , due to appropriate heat application (heat-on) to the buffer layer 280, the pickup portion 234 of the adhesive layer 230 undergoes surface thermal expansion, increasing the volume of the rounded shape of the protrusion and improving adhesion, thereby increasing the contact area with the light emitting element.

[0173] Reference Fig. 10D, the light emitting element transfer stamp 200 is placed above the growth substrate 310 on which the plurality of light emitting elements 10 are grown, so that the adhesive layer 230 is aligned above the light emitting elements 10 .

[0174] Reference Fig. 10E When the buffer layer 280 of the light emitting element transfer stamp 200 is turned on and heated, the adhesive layer 230 contacts the light emitting element 10 on the growth substrate 310 .

[0175] Reference Fig.10F Due to the heat application, the adhesive layer 230 softens while in contact with the light emitting element 10 on the growth substrate 310 , and the contact area with the light emitting element 10 is increased by the expanded pickup portion 234 , thereby enabling the light emitting element 10 to be picked up from the growth substrate 310 .

[0176] In this case, the light emitting element 10 on the growth substrate 310 is separated by a separation means such as laser, so that the light emitting element transfer stamp 200 can pick up the light emitting element 10 by simply performing a pickup operation.

[0177] When pickup is performed through the adhesive layer 230 , heat applied to the buffer layer 280 may cause the surface of the viscoelastic material of the adhesive layer 230 to expand, thereby providing advantageous characteristics for pickup.

[0178] After the light emitting element 10 is picked up, heat application is stopped (heating off) to allow the adhesive layer 230 to shrink, thereby minimizing the contact area between the adhesive layer 230 and the light emitting element 10 .

[0179] Reference Figure 10G , the light emitting element transfer stamp 200 that has picked up the light emitting element 10 is moved to the transfer substrate 110 and aligned above a predetermined pixel area of ​​the transfer substrate 110, and then, in this case, heat application is stopped to minimize the contact area between the adhesive layer 230 of the light emitting element transfer stamp 200 and the light emitting element 10.

[0180] Thereafter, the light emitting element 10 is placed and transferred from the light emitting element transfer stamp 200 onto the pixel region (not shown) using the adhesive property of an adhesive layer (not shown) provided in the pixel region of the transfer substrate 110 .

[0181] Thus, when the light emitting element is placed on the transfer substrate 110, the temperature is lowered by stopping the heat application (heating off) so that the heat-expanded adhesive layer 230 contracts, reducing the contact area between the adhesive layer 230 and the light emitting element 10, thereby reducing the adhesive force. As a result, the light emitting element 10 can be easily placed on the transfer substrate 110 from the adhesive layer 230.

[0182] According to the present invention, the light-emitting element transfer stamp 200 has predetermined adhesion (or adsorption) characteristics, so that the light-emitting element 10 set at a predetermined position can be selectively picked up from the growth substrate 310 by the adhesive force, and when the adhesive force is released, the light-emitting element 10 can be transferred to the corresponding pixel of the transfer substrate 110.

[0183] In the following, reference will be made to Figures 11 to 14 A light emitting element transfer stamp according to another embodiment of the present invention is described.

[0184] Fig.11 is a cross-sectional view illustrating a light emitting element transfer stamp according to another embodiment of the present invention.

[0185] Reference Fig.11 According to another embodiment of the present invention, a light emitting element transfer stamp 400 for a display device includes: a stamp substrate 410; insertion grooves 420 formed at regular intervals in the stamp substrate 410; an adhesive layer 430 disposed in the insertion grooves 420; and a light emitting element transfer stamp 400 disposed or stacked on the adhesive layer 430 to adhere to a light emitting element grown on a growth substrate (not shown, see Fig. 6A 310) on the light emitting element (not shown, see Fig. 6A 10) of the pick-up adhesive layer 436; a passivation layer 440 disposed on the exposed top surface of the stamp substrate 410 and on the exposed side surfaces of the adhesive layer 430 and the pick-up adhesive layer 436; and a buffer layer 450 disposed on the rear surface of the stamp substrate 410 to improve heat application and balancing effects.

[0186] The stamp substrate 410 may be used as a substrate for transferring the light emitting element 10 from a growth substrate (not shown, see Fig. 6A 310) is transferred to a transfer substrate (not shown, see Figure 6B 110) transfer device.

[0187] A quartz substrate, a sapphire substrate, or a silicon substrate may be used as the stamp substrate 410. However, the present invention is not necessarily limited thereto.

[0188] The insertion groove 420 can be used to suppress the left-right movement caused by the contraction and expansion of the adhesive layer 430 made of the viscoelastic material due to thermal deformation. In particular, when heat is applied to the buffer layer 450 provided on the rear surface of the stamp substrate 410 (heating is turned on), the insertion groove 420 is used to suppress the risk that may occur due to the contraction and expansion of the side surface of the adhesive layer 430 made of the viscoelastic material, that is, the misalignment caused by the lateral position change of the adhesive layer 430.

[0189] The insertion groove 420 may have a width ranging from 1 μm to 1000 μm, and a depth ranging from 0.1 μm to 500 μm, but is not necessarily limited thereto. The insertion groove 420 may have a quadrilateral, circular, or polygonal shape, but is not necessarily limited thereto.

[0190] The adhesive layer 430 may include: a support portion 432 which is inserted and fixed in the insertion groove 420; and a pick-up portion 434 which is formed as one body with the support portion 432 and protrudes above the insertion groove 420 and above the top surface of the stamp substrate 410 located above the side surface of the insertion groove 420.

[0191] The pickup adhesive layer 436 disposed on the adhesive layer 430 may include a second pickup portion 436 that picks up the substrate grown on the growth substrate (not shown, see Fig. 6A 310) on the light emitting element (not shown, see Fig. 6A 10).

[0192] The adhesive layer 430 may be made of a high-hardness material having thermal expansion resistance, and the pickup adhesive layer 436 may be made of a low-hardness material. The adhesive layer 430 may have a higher hardness than the pickup adhesive layer 436.

[0193] The pickup adhesive layer 436 is used to pick up the light emitting element by utilizing the surface adhesive property of its material. The application of the flexible viscoelastic material allows the light emitting elements of various shapes, structures and sizes to be picked up without the need for a complex spring structure as in conventional technology.

[0194] The pickup adhesive layer 436 may have a quadrilateral, circular, or polygonal shape, but is not necessarily limited thereto.

[0195] The materials of the adhesive layer 430 and the pickup adhesive layer 436 may include PDMS, PAC, urethane-based, acrylic-based, or epoxy-based materials, but a high-hardness material having thermal expansion resistance needs to be used for the adhesive layer, and a low-hardness material needs to be used for the pickup adhesive layer 436. However, the present invention is not necessarily limited thereto.

[0196] Since the support portion 432 of the adhesive layer 430 is inserted and supported within the insertion groove 420 , lateral contraction / expansion of the adhesive layer 430 may be suppressed by the insertion groove 420 , thereby increasing positional accuracy.

[0197] Due to the heat applied from the rear surface of the stamp substrate 410, the viscoelastic materials of the adhesive layer 430 and the pickup adhesive layer 436 may undergo thermal expansion and deformation to become a shape that is conducive to picking up the light emitting element. In particular, the surface shape of the pickup adhesive layer 436 may become a convex shape protruding in the vertical direction of the stamp substrate 410, specifically, a rounded shape.

[0198] The passivation layer 440 is used to suppress thermal expansion and deformation of the adhesive layer 430 and the pickup adhesive layer 436 in the lateral direction, and to guide thermal expansion and deformation through the upper exposure of the adhesive layer 430 and the pickup adhesive layer 436. The passivation layer 440 may be made of a material containing Al. 2 O 3 The passivation layer 440 may be made of an inorganic film material having a low thermal expansion coefficient or an inorganic film material such as ceramic. However, it is not necessarily limited thereto. The thickness of the passivation layer 440 is not limited.

[0199] When heat is applied to the stamp substrate 410 , the viscoelastic material of the pickup adhesive layer 436 may thermally expand and deform to be exposed upward, causing the surface shape of the pickup adhesive layer 436 to be changed into a shape that is conducive to picking up the light emitting element.

[0200] The buffer layer 450 is a layer for transferring heat to the viscoelastic material, and for further enhancing or weakening the surface adhesive properties of the viscoelastic material according to the applied heat. Typically, the adhesive properties allow the light emitting element to be picked up even at room temperature, but as the surface of the material degrades through contact with air, a situation where the surface adhesive properties weaken may occur.

[0201] The buffer layer 450 may be made of a thermally conductive resin material, a thermally conductive polymer material, a thermally conductive metal material, or the like.

[0202] As the thermally conductive resin material, a material obtained by adding graphite, Al, etc. to a resin material may be used. The thermally conductive resin material used as the material of the buffer layer 450 is not limited, and the thickness of the buffer layer 450 is also not limited.

[0203] The use of thermally conductive resin can improve the balance of the transfer process at the time of pick / place of the light emitting element.

[0204] The thermally conductive polymer material may include polyethylene, polycarbonate, polyamide / polyimide, polybenzimidazole, ethylene-tetrafluoroethylene copolymer, polyacrylonitrile-butadiene-styrene, and other thermally conductive materials. However, it is not necessarily limited thereto. For example, the thermally conductive polymer material may have a thermal conductivity ranging from 5×10-1 to 1×10 2 Thermal conductivity (Wm -1 K -1 ). However, it is not necessarily limited thereto.

[0205] As the thermally conductive metal material, metals such as Al, Zn, Au, Pt, V, and Ni or alloys thereof may be used. The thermally conductive metal material may have a thermal conductivity ranging from 1×101 to 1×10 3 Thermal conductivity (Wm -1 K -1 ). However, it is not necessarily limited thereto.

[0206] When heat is applied to the buffer layer 450 in an appropriate temperature range, for example, from 30° C. to 250° C., surface adhesion properties of the adhesive layer 430 and the pickup adhesive layer 436 may be enhanced, thereby improving pickup yield. The temperature range for applying heat to the buffer layer 450 is not limited thereto.

[0207] Furthermore, when picking up via the pickup adhesive layer 436, heat applied to the buffer layer 450 (heat-on) may cause the surface of the viscoelastic material of the pickup adhesive layer 436 to expand, thereby providing advantageous properties for picking up.

[0208] When the transfer substrate (not shown, see Figure 6B When placing the light emitting element 10 on the transfer substrate 110, the temperature is lowered by stopping the heat application (heating off) so that the heat-expanded pickup adhesive layer 436 contracts, thereby reducing the contact area between the pickup adhesive layer 436 and the light emitting element 10, thereby reducing the adhesive force. As a result, the light emitting element 10 can be easily placed on the transfer substrate 110 from the pickup adhesive layer 436.

[0209] According to another embodiment of the present invention, the light-emitting element transfer stamp 400 has predetermined adhesion (or adsorption) characteristics, so that the light-emitting element 10 set at a predetermined position can be selectively picked up from the growth substrate by the adhesion force, and when the adhesion force is released, the light-emitting element 10 can be transferred to the corresponding pixel of the transfer substrate 110.

[0210] Fig.12 is a cross-sectional view illustrating a light emitting element transfer stamp according to still another embodiment of the present invention.

[0211] Reference Fig.12 According to another embodiment of the present invention, a light emitting element transfer stamp 500 for a display device includes: a stamp substrate 510; a plurality of insertion grooves 520 formed at regular intervals in the stamp substrate 510; and a plurality of insertion grooves 520 respectively disposed in the plurality of insertion grooves 520 to pick up / place a light emitting element grown on a growth substrate (not shown, see Fig. 6A 310) on the light emitting element (not shown, see Fig. 6A 10) of multiple adhesive layers 530; a passivation layer 540, which is arranged on the exposed top surface of the stamp substrate 510, the exposed side surface of the adhesive layer 530, and a portion of the top surface of the adhesive layer 530 or the top surface of the adhesive layer 530 extending from its side surface; and a buffer layer 550 arranged on the rear surface of the stamp substrate 510 to improve heat application and balancing effects.

[0212] The stamp substrate 510 may be used as a substrate for transferring the light emitting element 10 from a growth substrate (not shown, see Fig. 6A 310) is transferred to a transfer substrate (not shown, see Figure 6B110) transfer device.

[0213] A quartz substrate, a sapphire substrate, or a silicon substrate may be used as the stamp substrate 510. However, the present invention is not necessarily limited thereto.

[0214] The insertion groove 520 can be used to suppress the left-right movement of the adhesive layer 530 made of a viscoelastic material due to the contraction and expansion caused by thermal deformation. In particular, when heat is applied to the buffer layer 550 provided on the rear surface of the stamp substrate 510 (heating is turned on), the insertion groove 520 is used to suppress the risk that may occur due to the contraction and expansion of the side surface of the adhesive layer 530 made of a viscoelastic material, that is, the misalignment caused by the lateral position change of the adhesive layer 530.

[0215] The insertion groove 520 may have a width ranging from 1 μm to 1000 μm, and a depth ranging from 0.1 μm to 500 μm, but is not necessarily limited thereto. The insertion groove 520 may have a quadrilateral, circular, or polygonal shape, but is not necessarily limited thereto.

[0216] The adhesive layer 530 may include a support portion 532 inserted and fixed in the insertion groove 520 , and a pickup portion 534 formed integrally with the support portion 532 and disposed on a top surface of the stamp substrate 510 contacting a side surface of the insertion groove 520 .

[0217] The adhesive layer 530 is used to pick up the light emitting element by utilizing the surface adhesive property of the material thereof. The application of the flexible viscoelastic material allows picking up light emitting elements of various shapes, structures and sizes without requiring a complex spring structure as in conventional technology.

[0218] The adhesive layer 530 may have a quadrilateral, circular, or polygonal shape, but is not necessarily limited thereto.

[0219] The material of the adhesive layer 530 may include PDMS, PAC, urethane, acrylic or epoxy materials, but is not necessarily limited thereto.

[0220] Since the support portion 532 of the adhesive layer 530 is inserted and supported within the insertion groove 520 , lateral contraction / expansion of the adhesive layer 530 may be suppressed by the insertion groove 520 , thereby increasing transfer accuracy.

[0221] Due to the heat applied from the rear surface of the stamp substrate 510, the viscoelastic material of the adhesive layer 530 may undergo thermal expansion and deformation to change into a shape that is conducive to picking up the light emitting element. In particular, the surface shape of the adhesive layer 530 may be changed into a convex shape protruding in the vertical direction of the stamp substrate 510, specifically, a rounded shape.

[0222] The passivation layer 540 is disposed on the exposed top surface of the stamp substrate 510 and further includes an extension portion 542 surrounding the side surface of the pickup portion 534 of the adhesive layer 530 and an edge portion of the top surface of the pickup portion 534 meeting at the side surface thereof.

[0223] The passivation layer 540 is used to suppress thermal expansion and deformation of the adhesive layer 530 in the lateral direction, and is used to guide thermal expansion and deformation through the upper exposure of the adhesive layer 530. The passivation layer 540 may be made of a material containing Al. 2 O 3 The passivation layer 540 may be made of an inorganic film material having a low thermal expansion coefficient or an inorganic film material such as ceramic. However, it is not necessarily limited thereto. The thickness of the passivation layer 540 is not limited.

[0224] Since the passivation layer 540 includes an extension portion 542 of the side surface and top surface edge portion surrounding the pick-up portion 534 of the adhesive layer 530, it can be used to prevent the adhesive layer 530 from changing its position in the left-right direction (which is the horizontal direction of the stamp substrate 510) due to thermal expansion or lateral contraction when heat is applied (heating is turned on) or when heat is not applied (heating is turned off).

[0225] The buffer layer 550 is a layer for transferring heat to the viscoelastic material, and for further enhancing or weakening the surface adhesive properties of the viscoelastic material according to the heat applied. Typically, the adhesive properties allow the light emitting element to be picked up even at room temperature, but as the surface of the material degrades through contact with air, a situation where the surface adhesive properties are weakened may occur.

[0226] The buffer layer 550 may be made of a thermally conductive resin material, a thermally conductive polymer material, a thermally conductive metal material, or the like.

[0227] As the thermally conductive resin material, a material obtained by adding graphite, Al, etc. to a resin material may be used. The thermally conductive resin material used as the material of the buffer layer 550 is not limited, and the thickness of the buffer layer 550 is also not limited.

[0228] The use of thermally conductive resin can improve the balance of the transfer process at the time of pick / place of the light emitting element.

[0229] The thermally conductive polymer material may include polyethylene, polycarbonate, polyamide / polyimide, polybenzimidazole, ethylene-tetrafluoroethylene copolymer, polyacrylonitrile-butadiene-styrene, and other thermally conductive materials. However, it is not necessarily limited thereto. For example, the thermally conductive polymer material may have a thermal conductivity ranging from 5×10-1 to 1×10 2 Thermal conductivity (Wm -1 K -1 ). However, it is not necessarily limited thereto.

[0230] As the thermally conductive metal material, metals such as Al, Zn, Au, Pt, V, and Ni or alloys thereof may be used. The thermally conductive metal material may have a thermal conductivity ranging from 1×101 to 1×10 3 Thermal conductivity (Wm -1 K -1 ). However, it is not necessarily limited thereto.

[0231] In particular, when heat is applied to the buffer layer 550 in an appropriate temperature range, for example, from 30° C. to 250° C., surface adhesive properties of the adhesive layer 530 may be enhanced, thereby improving pickup yield. The temperature range for applying heat to the buffer layer 550 is not limited thereto.

[0232] Furthermore, when picking up is performed via the adhesive layer 530 , heat applied to the buffer layer 550 may cause the surface of the viscoelastic material of the adhesive layer 530 to expand, thereby providing advantageous characteristics for picking up.

[0233] When the transfer substrate (not shown, see Figure 6B When the light emitting element 10 is placed on the adhesive layer 530 (see FIG. 110 ), the temperature is lowered by stopping the heat application (heating off) so that the heat-expanded adhesive layer 530 contracts, thereby reducing the gap between the adhesive layer 530 and the light emitting element (see FIG. 110 ). Figure 6B As a result, the light emitting element 10 can be easily placed on the transfer substrate 110 from the adhesive layer 530.

[0234] According to another embodiment of the present invention, the light-emitting element transfer stamp 500 has predetermined adhesion (or adsorption) characteristics, so that the light-emitting element 10 set at a predetermined position can be selectively picked up from the growth substrate by the adhesion force, and when the adhesion force is released, the light-emitting element 10 can be transferred to the corresponding pixel of the transfer substrate 110.

[0235] Fig.13 is a cross-sectional view illustrating a light emitting element transfer stamp according to still another embodiment of the present invention.

[0236] Reference Fig.13 According to another embodiment of the present invention, a light emitting element transfer stamp 600 for a display device includes: a stamp substrate 610; insertion grooves 620 formed at regular intervals in the stamp substrate 610; and a light emitting element transfer stamp 600 for picking up / placing a light emitting element grown on a growth substrate (not shown, see Fig. 6A 310) on the light emitting element (not shown, see Fig. 6A10) of the adhesive layer 630; a passivation layer 640, which is arranged on the exposed top surface of the stamp substrate 610, the exposed side surface of the adhesive layer 630, and a portion of the top surface of the adhesive layer 630; and a buffer layer 650 arranged on the rear surface of the stamp substrate 610 to improve heat application and balancing effects.

[0237] The stamp substrate 610 may be used as a substrate for transferring the light emitting element 10 from a growth substrate (not shown, see Fig. 6A 310) is transferred to a transfer substrate (not shown, see Figure 6B 110) transfer device.

[0238] A quartz substrate, a sapphire substrate, or a silicon substrate may be used as the stamp substrate 610. However, the present invention is not necessarily limited thereto.

[0239] A plurality of uneven grooves 622 having a fine structure may be formed on the bottom surface of the insertion groove 620. The plurality of uneven grooves 622 may be formed by a nanoimprint process. However, the present invention is not necessarily limited thereto.

[0240] The plurality of insertion grooves 620 may be used to suppress the left-right movement of the adhesive layer 630 made of a viscoelastic material due to contraction or expansion caused by thermal deformation. In particular, when heat is applied to the buffer layer 650 provided on the rear surface of the stamp substrate 610 (heating is turned on), the plurality of insertion grooves 620 may be used to suppress the risk that may occur due to contraction and expansion of the side surface of the adhesive layer 630 made of a viscoelastic material, that is, misalignment caused by a lateral position change of the adhesive layer 630.

[0241] The plurality of concavoconvex grooves 622 formed on the bottom surface of the insertion groove 620 may serve to improve the adhesive and support characteristics at the interface between the adhesive layer 630 and the stamp substrate 610. In addition, the plurality of concavoconvex grooves 622 may improve the lateral contraction and expansion characteristics of the adhesive layer 630.

[0242] Since multiple concave-convex grooves 622 are formed on the bottom surface of the insertion groove 620, the adhesion between the viscoelastic material and the insertion groove 620 can be improved through the anchor effect of this structure, and the suppression function of lateral shrinkage or expansion caused by heat can be improved, thereby ultimately improving the position accuracy of the light-emitting element during transfer.

[0243] The width of the plurality of insertion grooves 620 may range from 1 μm to 1000 μm, and the depth thereof may range from 0.1 μm to 500 μm, but is not necessarily limited thereto. The plurality of insertion grooves 620 may have a quadrilateral, circular, or polygonal shape, but is not necessarily limited thereto.

[0244] The adhesive layer 630 may include a support portion 632 inserted and fixed in the insertion groove 620 , and a pickup portion 634 formed integrally with the support portion 632 and disposed on a top surface of the stamp substrate 610 contacting a side surface of the insertion groove 620 .

[0245] The adhesive layer 630 is used to pick up the light emitting element by utilizing the surface adhesive property of the material thereof. The application of the flexible viscoelastic material allows picking up light emitting elements of various shapes, structures and sizes without requiring a complex spring structure as in conventional technology.

[0246] The adhesive layer 630 may have a quadrilateral, circular, or polygonal shape, but is not necessarily limited thereto.

[0247] The material of the adhesive layer 630 may include PDMS, PAC, urethane-based, acrylic-based, or epoxy-based materials, but is not necessarily limited thereto.

[0248] Since the support portion 632 of the adhesive layer 630 is inserted and supported within the insertion groove 620 , lateral contraction / expansion of the adhesive layer 630 may be suppressed by the insertion groove 620 , thereby increasing positional accuracy.

[0249] Due to the heat applied from the rear surface of the stamp substrate 610, the viscoelastic material of the adhesive layer 630 may undergo thermal expansion and deformation to change into a shape that is conducive to picking up the light emitting element. In particular, the surface shape of the adhesive layer 630 may be changed into a convex shape protruding in the vertical direction of the stamp substrate 610, specifically, a rounded shape.

[0250] The passivation layer 640 is disposed on the exposed top surface of the stamp substrate 610 , and further includes an extension portion 642 that surrounds a side surface of the pickup portion 634 of the adhesive layer 630 and an edge portion of the top surface.

[0251] The passivation layer 640 is used to suppress the thermal expansion and deformation of the adhesive layer 630 in the lateral direction, and is used to guide the thermal expansion deformation through the upper exposure of the adhesive layer 630. The passivation layer 640 may be made of a material containing Al. 2 O 3 The passivation layer 640 may be made of an inorganic film material having a low thermal expansion coefficient or an inorganic film material such as ceramic. However, it is not necessarily limited thereto. The thickness of the passivation layer 640 is not limited.

[0252] In particular, the passivation layer 640 includes an extension portion 642 surrounding the side surface and top surface edge portions of the pick-up portion 634 of the adhesive layer 630. Therefore, the passivation layer 640 may serve to prevent a position change of the adhesive layer 630 in the left-right direction (which is a horizontal direction of the stamp substrate 610) due to thermal expansion or lateral contraction when heat is applied (heating on) or when heat is not applied (heating off).

[0253] The buffer layer 650 is a layer for transferring heat to the viscoelastic material, and for further enhancing or weakening the surface adhesive properties of the viscoelastic material according to the applied heat. Typically, the adhesive properties allow the light emitting element to be picked up even at room temperature, but as the surface of the material degrades through contact with air, a situation where the surface adhesive properties weaken may occur.

[0254] The buffer layer 650 may be made of a thermally conductive resin material, a thermally conductive polymer material, a thermally conductive metal material, or the like.

[0255] As the thermally conductive resin material, a material obtained by adding graphite, Al, etc. to a resin material may be used. The thermally conductive resin material used as the material of the buffer layer 650 is not limited, and the thickness of the buffer layer 650 is also not limited.

[0256] The use of thermally conductive resin can improve the balance of the transfer process at the time of pick / place of the light emitting element.

[0257] The thermally conductive polymer material may include polyethylene, polycarbonate, polyamide / polyimide, polybenzimidazole, ethylene-tetrafluoroethylene copolymer, polyacrylonitrile-butadiene-styrene, and other thermally conductive materials. However, it is not necessarily limited thereto. For example, the thermally conductive polymer material may have a thermal conductivity ranging from 5×10-1 to 1×10 2 Thermal conductivity (Wm -1 K -1 ). However, it is not necessarily limited thereto.

[0258] As the thermally conductive metal material, metals such as Al, Zn, Au, Pt, V, and Ni or alloys thereof may be used. The thermally conductive metal material may have a thermal conductivity ranging from 1×101 to 1×10 3 Thermal conductivity (Wm -1 K -1 ). However, it is not necessarily limited thereto.

[0259] In particular, when heat is applied to the buffer layer 650 in an appropriate temperature range, for example, from 30° C. to 250° C., surface adhesive properties of the adhesive layer 630 may be enhanced, thereby improving pickup yield. The temperature range for applying heat to the buffer layer 650 is not limited thereto.

[0260] Furthermore, when picking up is performed via the adhesive layer 630 , heat applied to the buffer layer 650 may cause the surface of the viscoelastic material of the adhesive layer 630 to expand, thereby providing advantageous characteristics for picking up.

[0261] When the transfer substrate (not shown, see Figure 6B When the light emitting element 10 is placed on the adhesive layer 630 (see FIG. 110 ), the temperature is lowered by stopping the heat application (heating off) so that the heat-expanded adhesive layer 630 contracts, thereby reducing the gap between the adhesive layer 630 and the light emitting element (see FIG. 110 ). Figure 6BAs a result, the light emitting element 10 can be easily placed on the transfer substrate 110 from the adhesive layer 630.

[0262] According to another embodiment of the present invention, the light-emitting element transfer stamp 600 has predetermined adhesion (or adsorption) characteristics, so that the light-emitting element 10 set at a predetermined position can be selectively picked up from the growth substrate by the adhesion force, and when the adhesion force is released, the light-emitting element 10 can be transferred to the corresponding pixel of the transfer substrate 110.

[0263] Fig.14 is a cross-sectional view illustrating a light emitting element transfer stamp according to still another embodiment of the present invention.

[0264] Reference Fig.14 According to another embodiment of the present invention, a light emitting element transfer stamp 700 for a display device includes: a stamp substrate 710; insertion grooves 720 formed at regular intervals in the stamp substrate 710; and a light emitting element transfer stamp 700 for picking up / placing a light emitting element grown on a growth substrate (not shown, see FIG. 1 ). Fig. 6A 310) on the light emitting element (not shown, see Fig. 6A The present invention also includes an adhesive layer 730 of 10) of the mold substrate 710; a passivation layer 740 disposed on the exposed top surface of the mold substrate 710 and the exposed side surface of the adhesive layer 730; a metal heating line 750 disposed on the rear surface of the mold substrate 710; and a buffer layer 760 disposed on the metal heating line 750 to improve the balance effect of pick-up / placement of the light-emitting element. The metal heating line 750 may be disposed between the mold substrate 710 and the buffer layer 760.

[0265] The stamp substrate 710 may be used as a substrate for transferring the light emitting element 10 from a growth substrate (not shown, see Fig. 6A 310) is transferred to a transfer substrate (not shown, see Figure 6B 110) transfer device.

[0266] A quartz substrate, a sapphire substrate, or a silicon substrate may be used as the stamp substrate 710. However, the present invention is not necessarily limited thereto.

[0267] The insertion groove 720 can be used to suppress the left-right movement of the adhesive layer 730 made of a viscoelastic material due to contraction or expansion caused by thermal deformation. In particular, when heat is applied to the buffer layer 760 provided on the rear surface of the stamp substrate 710 (heating is turned on), the insertion groove 720 is used to suppress the risk that may occur due to contraction and expansion of the side surface of the adhesive layer 730 made of a viscoelastic material, that is, misalignment caused by lateral position change of the adhesive layer 730, thereby improving position accuracy.

[0268] The insertion groove 720 may have a width ranging from 1 μm to 1000 μm, and a depth ranging from 0.1 μm to 500 μm, but is not necessarily limited thereto. The insertion groove 720 may have a quadrilateral, circular, or polygonal shape, but is not necessarily limited thereto.

[0269] The adhesive layer 730 may include a support portion 732 inserted and fixed in the insertion groove 720 , and a pickup portion 734 formed integrally with the support portion 732 and disposed on a top surface of the stamp substrate 710 contacting a side surface of the insertion groove 720 .

[0270] The adhesive layer 730 is used to pick up the light emitting element by utilizing the surface adhesive property of the material thereof. The application of the flexible viscoelastic material allows picking up light emitting elements of various shapes, structures and sizes without requiring a complex spring structure as in conventional technology.

[0271] The adhesive layer 730 may have a quadrilateral, circular, or polygonal shape, but is not necessarily limited thereto.

[0272] The material of the adhesive layer 730 may include PDMS, PAC, urethane, acrylic or epoxy materials, but is not necessarily limited thereto.

[0273] Since the support portion 732 of the adhesive layer 730 is inserted and supported in the insertion groove 720 , lateral contraction / expansion of the adhesive layer 730 may be suppressed by the insertion groove 720 , thereby increasing transfer position accuracy.

[0274] Due to the heat applied from the rear surface of the stamp substrate 710, the viscoelastic material of the adhesive layer 730 may undergo thermal expansion and deformation to change into a shape that is conducive to picking up the light emitting element. In particular, the surface shape of the adhesive layer 730 may be changed into a convex shape protruding in the vertical direction of the stamp substrate 710, specifically, a rounded shape.

[0275] The passivation layer 740 is disposed on the exposed top surface of the stamp substrate 710 and further includes an extension portion 742 surrounding the side surface of the pickup portion 734 of the adhesive layer 730 and an edge portion of the top surface of the pickup portion 734 meeting at the side surface thereof.

[0276] The passivation layer 740 is used to suppress thermal expansion and deformation of the adhesive layer 730 in the lateral direction, and is used to guide thermal expansion and deformation through the upper exposure of the adhesive layer 730. The passivation layer 740 may be made of a material containing Al. 2 O 3 The passivation layer 740 may be made of an inorganic film material having a low thermal expansion coefficient or an inorganic film material such as ceramic. However, it is not necessarily limited thereto. The thickness of the passivation layer 740 is not limited.

[0277] In particular, since the passivation layer 740 includes an extension portion 742 of the side surface and the top surface edge portion of the pick-up portion 734 surrounding the adhesive layer 730, it can be used to prevent the adhesive layer 730 from changing its position in the left-right direction (which is the horizontal direction of the stamp substrate 710) due to thermal expansion or lateral contraction when heat is applied (heating is on) or not applied (heating is off).

[0278] The metal heating wire 750 may be employed as a means for applying heat. By allowing heat to be applied via the metal heating wire 750, heat transfer may be effectively performed via the buffer layer 760, thereby improving the surface adhesive property of the adhesive layer 730.

[0279] The buffer layer 760 is a layer for transferring heat to the viscoelastic material, and for further enhancing or weakening the surface adhesive properties of the viscoelastic material according to the heat applied. Typically, the adhesive properties allow the light emitting element to be picked up even at room temperature, but as the surface of the material degrades through contact with air, a situation where the surface adhesive properties are weakened may occur.

[0280] The buffer layer 760 may be made of a thermally conductive resin material, a thermally conductive polymer material, a thermally conductive metal material, or the like.

[0281] As the thermally conductive resin material, a material obtained by adding graphite, Al, etc. to a resin material may be used. The thermally conductive resin material used as the material of the buffer layer 760 is not limited, and the thickness of the buffer layer 760 is also not limited.

[0282] The use of thermally conductive resin can improve the balance of the transfer process at the time of pick / place of the light emitting element.

[0283] The thermally conductive polymer material may include polyethylene, polycarbonate, polyamide / polyimide, polybenzimidazole, ethylene-tetrafluoroethylene copolymer, polyacrylonitrile-butadiene-styrene, and other thermally conductive materials. However, it is not necessarily limited thereto. For example, the thermally conductive polymer material may have a thermal conductivity (Wm) ranging from 5×10-1 to 1×102. -1 K -1 ). However, it is not necessarily limited thereto.

[0284] As the thermally conductive metal material, metals such as Al, Zn, Au, Pt, V, and Ni or alloys thereof may be used. The thermally conductive metal material may have a thermal conductivity ranging from 1×101 to 1×10 3 Thermal conductivity (Wm -1 K -1 ). However, it is not necessarily limited thereto.

[0285] In particular, when heat is applied to the buffer layer 760 in an appropriate temperature range, for example, from 30° C. to 250° C., surface adhesive properties of the adhesive layer 730 may be enhanced, thereby improving pickup yield. The temperature range for applying heat to the buffer layer 760 is not limited thereto.

[0286] Furthermore, when picking up via the adhesive layer 730, applying heat via the metal heating wire 750 may improve heat transfer through the buffer layer 760, causing the surface of the viscoelastic material of the adhesive layer 730 to expand, thereby providing advantageous properties for picking up.

[0287] When the transfer substrate (not shown, see Figure 6B When placing the light emitting element 10 on the transfer substrate 110, the temperature is lowered by stopping the heat application (heating off) so that the heat-expanded adhesive layer 730 contracts, thereby reducing the contact area between the adhesive layer 730 and the light emitting element 10, thereby reducing the adhesive force. As a result, the light emitting element 10 can be easily placed on the transfer substrate 110 from the adhesive layer 730.

[0288] According to another embodiment of the present invention, the light-emitting element transfer stamp 700 has predetermined adhesion (or adsorption) characteristics, so that the light-emitting element 10 set at a predetermined position can be selectively picked up from the growth substrate by the adhesion force, and when the adhesion force is released, the light-emitting element 10 can be transferred to the corresponding pixel of the transfer substrate 110.

[0289] As described above, in order to achieve the pick-up / placement of the light-emitting element without the need for a complex spring structure and voltage application, a stamp structure in which an insertion groove is formed to fix the adhesive layer in the stamp substrate can be used, thereby suppressing the misalignment caused by the lateral position change of the adhesive layer 730 and improving the position accuracy of the transfer of the light-emitting element.

[0290] According to the present invention, a pick / place transfer process is possible through a simple bonding material process and a low temperature heating control method.

[0291] According to the present invention, the risk of damage to light emitting element chips can be reduced, the yield loss and damage caused by defects in pickup array components can be improved, and the component life can be increased.

[0292] According to the present invention, by providing a buffer layer on the rear surface of a stamp substrate on which a light emitting element is picked up, a stamp substrate can be formed so that face-to-face adhesion balance is favorable during a pick / place process, thereby expecting improvement in yield.

[0293] According to the present invention, the manufacturing process of the stamp is simple, thereby reducing the manufacturing cost and being advantageous in terms of component consistency.

[0294] The light emitting element transfer stamp according to various embodiments of the present invention can be described as follows.

[0295] According to one embodiment of the present invention, a light-emitting element transfer stamp may include: a stamp substrate; a plurality of insertion grooves arranged at regular intervals in the stamp substrate; a plurality of adhesive layers, the adhesive layers being respectively arranged in the plurality of insertion grooves and on the stamp substrate in contact with the insertion grooves; a passivation layer arranged on the stamp substrate between the plurality of adhesive layers; and a buffer layer arranged on the rear surface of the stamp substrate.

[0296] According to the light emitting element transfer stamp of the present invention, a plurality of concavo-convex grooves may be provided on the bottom surface of the insertion groove.

[0297] According to the light emitting element transfer stamp of the present invention, the adhesive layer may extend within the insertion groove and on the stamp substrate above the side surface of the insertion groove to protrude above the stamp substrate.

[0298] According to the light emitting element transfer stamp of the present invention, the adhesive layer may include PDMS, PAC, urethane-based, acrylic-based or epoxy-based materials.

[0299] According to the light emitting element transfer stamp of the present invention, a pickup adhesive layer may be stacked on the adhesive layer.

[0300] According to the light emitting element transfer stamp of the present invention, the adhesive layer may be made of a high hardness material having resistance to thermal expansion, the pickup adhesive layer may be made of a low hardness material, or the adhesive layer and the pickup adhesive layer may be made of materials having different hardnesses.

[0301] According to the light-emitting element transfer stamp of the present invention, the passivation layer can be arranged on the exposed top surface of the stamp substrate and the side surface of the adhesive layer, or can be arranged on the exposed top surface of the stamp substrate, the side surface of the adhesive layer and the top surface of the adhesive layer extending from its side surface.

[0302] According to the light emitting element transfer stamp of the present invention, the passivation layer may include Al 2 O 3 and at least one of an inorganic film material containing ceramics and having a low thermal expansion coefficient.

[0303] According to the light emitting element transfer stamp of the present invention, the buffer layer may include a thermally conductive resin material, a thermally conductive polymer material or a thermally conductive metal material.

[0304] According to the light emitting element transfer stamp of the present invention, the thermally conductive resin material may include a material obtained by adding graphite and Al to a resin material, the thermally conductive polymer material may include at least one of polyethylene, polycarbonate, polyamide / polyimide, polybenzimidazole, ethylene-tetrafluoroethylene copolymer, and polyacrylonitrile-butadiene-styrene, or may include a thermal conductivity (Wm) ranging from 5×10-1 to 1×102. -1 K -1 ), the thermally conductive metal material may include a metal such as Al, Zn, Au, Pt, V, and Ni or an alloy thereof, or may include a thermal conductivity ranging from 1×101 to 1×10 3 Thermal conductivity (Wm -1 K -1 ) of metal materials.

[0305] According to the light emitting element transfer stamp of the present invention, a metal heating line may be disposed between the stamp substrate and the buffer layer.

[0306] According to one embodiment of the present invention, a method for manufacturing a light-emitting element transfer stamp may include: forming a plurality of insertion grooves at regular intervals in a stamp substrate; disposing a plurality of adhesive layers in the plurality of insertion grooves and on the stamp substrate in contact with the plurality of insertion grooves; disposing a passivation layer on the stamp substrate between the plurality of adhesive layers; and disposing a buffer layer on the rear surface of the stamp substrate.

[0307] The method of manufacturing a light emitting element transfer stamp according to the present invention may further include: forming a plurality of concavo-convex grooves on a bottom surface of the insertion groove.

[0308] According to the method for manufacturing a light emitting element transfer stamp of the present invention, the adhesive layer may include PDMS, PAC, urethane-based, acrylic-based or epoxy-based materials.

[0309] The method of manufacturing a light emitting element transfer stamp according to the present invention may further include: stacking a pickup adhesive layer on the adhesive layer.

[0310] According to the method of manufacturing a light emitting element transfer stamp of the present invention, the adhesive layer may include a high hardness material having resistance to thermal expansion, and the pickup adhesive layer may include a low hardness material.

[0311] According to the method for manufacturing a light-emitting element transfer stamp of the present invention, the passivation layer can be arranged on the exposed top surface of the stamp substrate and on the side surface of the adhesive layer, or can be arranged on the exposed top surface of the stamp substrate, on the side surface of the adhesive layer, and on the top surface of the adhesive layer extending from its side surface.

[0312] According to the method for manufacturing a light emitting element transfer stamp of the present invention, the passivation layer may include Al 2 O 3 and at least one of an inorganic film material containing ceramics and having a low thermal expansion coefficient.

[0313] According to the method for manufacturing a light emitting element transfer stamp of the present invention, the buffer layer may include a thermally conductive resin material, a thermally conductive polymer material or a thermally conductive metal material.

[0314] The method for manufacturing a light emitting element transfer stamp according to the present invention may further include: providing a metal heating line between the stamp substrate and the buffer layer.

[0315] The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the above detailed description.

[0316] The contents of the specification described in the above problems to be solved, means for solving the problems, and effects do not specify essential features of the claims, so the scope of the claims is not limited by the items described in the contents of the specification.

[0317] Although the embodiments of the present invention are described in more detail with reference to the accompanying drawings, the present invention is not necessarily limited to these embodiments, and various modifications can be implemented without departing from the technical spirit of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but are intended to describe the technical spirit of the present invention, and the scope of the technical spirit of the present invention is not limited by these embodiments. Therefore, it should be understood that the above-mentioned embodiments are exemplary in all aspects and are not restrictive.

Claims

1. A light emitting element transfer stamp, comprising: Impression base; a plurality of insertion grooves arranged at regular intervals in the stamp substrate; a plurality of adhesive layers, the adhesive layers being respectively disposed in the plurality of insertion grooves and on the stamp substrate in contact with the insertion grooves; a passivation layer disposed on the stamp substrate between the plurality of adhesive layers; as well as A buffer layer is disposed on a rear surface of the stamp substrate. 2 . The light emitting element transfer stamp according to claim 1 , wherein a plurality of concavo-convex grooves are provided on a bottom surface of the insertion groove. 3 . The light emitting element transfer stamp according to claim 1 , wherein the adhesive layer extends within the insertion groove and on the stamp substrate above the side surface of the insertion groove to protrude above the stamp substrate. 4 . The light emitting element transfer stamp according to claim 1 , wherein the adhesive layer comprises PDMS, PAC, urethane, acrylic or epoxy materials. The light emitting element transfer stamp according to claim 1 , wherein a pick-up adhesive layer is stacked on the adhesive layer. 6 . The light emitting element transfer stamp according to claim 5 , wherein the adhesive layer is made of a high hardness material having resistance to thermal expansion, the pickup adhesive layer is made of a low hardness material, or the adhesive layer and the pickup adhesive layer are made of materials having different hardnesses.

7. The light-emitting element transfer stamp according to claim 1, wherein the passivation layer is disposed on the exposed top surface of the stamp substrate and on the side surface of the adhesive layer, or is disposed on the exposed top surface of the stamp substrate, on the side surface of the adhesive layer, and on the top surface of the adhesive layer extending from its side surface. 8 . The light emitting element transfer stamp according to claim 1 , wherein the passivation layer comprises at least one of an inorganic film material containing Al 2 O 3 and an inorganic film material containing ceramics having a low thermal expansion coefficient. 9 . The light emitting element transfer stamp according to claim 1 , wherein the buffer layer comprises a thermally conductive resin material, a thermally conductive polymer material or a thermally conductive metal material.

10. The light emitting element transfer stamp according to claim 9, wherein the thermally conductive resin material comprises a material obtained by adding graphite and Al to a resin material, The thermally conductive polymer material includes at least one of polyethylene, polycarbonate, polyamide / polyimide, polybenzimidazole, ethylene-tetrafluoroethylene copolymer and polyacrylonitrile-butadiene-styrene, or includes a thermal conductivity ranging from 5×10-1 to 1×10 2 Thermal conductivity (Wm -1 K -1 ) of polymer materials, The thermally conductive metal material includes a metal containing Al, Zn, Au, Pt, V and Ni or an alloy thereof, or includes a metal having a thermal conductivity ranging from 1×101 to 1×10 3 Thermal conductivity (Wm -1 K -1 ) of metal materials. 11 . The light emitting element transfer stamp according to claim 1 , wherein a metal heating line is disposed between the stamp substrate and the buffer layer.

12. A method for manufacturing a light emitting element transfer stamp, comprising: forming a plurality of insertion grooves at regular intervals in the stamp substrate; providing a plurality of adhesive layers in the plurality of insertion grooves and on the stamp substrate in contact with the plurality of insertion grooves; disposing a passivation layer on the stamp substrate between the plurality of adhesive layers; as well as A buffer layer is disposed on the rear surface of the stamp substrate.

13. The method according to claim 12, further comprising: A plurality of concavo-convex grooves are formed on a bottom surface of the insertion groove.

14. The method of claim 12, wherein the adhesive layer comprises PDMS, PAC, urethane-based, acrylic-based, or epoxy-based material.

15. The method according to claim 12, further comprising: A pick-up adhesive layer is stacked on the adhesive layer. 16 . The method of claim 15 , wherein the adhesive layer comprises a high-hardness material having resistance to thermal expansion, and the pickup adhesive layer comprises a low-hardness material.

17. The method according to claim 12, wherein the passivation layer is disposed on the exposed top surface of the stamp substrate and on the side surface of the adhesive layer, or on the exposed top surface of the stamp substrate, on the side surface of the adhesive layer, and on the top surface of the adhesive layer extending from its side surface. 18 . The method according to claim 12 , wherein the passivation layer comprises at least one of an inorganic film material containing Al 2 O 3 and an inorganic film material containing ceramic having a low thermal expansion coefficient. 19 . The method according to claim 12 , wherein the buffer layer comprises a thermally conductive resin material, a thermally conductive polymer material, or a thermally conductive metal material.

20. The method of claim 12, further comprising: A metal heating line is disposed between the stamp substrate and the buffer layer.

Images