KR20200001323A - Transfer head for micro led - Google Patents

Abstract

The present invention relates to a micro LED transfer head, which adsorbs a micro LED to transfer the same to a display substrate, and more specifically, to a micro LED transfer head, which adsorbs a micro LED through first adsorption force and second adsorption force different from each other, thereby solving a problem caused by position errors generated by bringing an adsorption surface of a micro LED transfer head in contact with an upper surface of a micro LED during transfer of the micro LED and a problem caused by damage to the micro LED and complementing inadequate adsorption of the micro LED.

Description

Micro LED transfer head {TRANSFER HEAD FOR MICRO LED}

The present invention relates to a micro LED transfer head for absorbing micro LEDs and transferring them to a display substrate.

Currently, the display market is still the mainstream, while OLED is rapidly becoming the mainstream by replacing LCD. As display companies are participating in the OLED market rush, Micro LED (hereinafter referred to as “micro LED”) display is emerging as another next generation display. Whereas the core materials of LCD and OLED are liquid crystal and organic materials, micro LED display is a display that uses LED chip of 1 ~ 100 micrometer (μm) unit as light emitting material.

When Cree applied for a patent on "Micro-light Emitting Diode Arrays with Improved Light Extraction" in 1999 (Registration No. 0731673), the research and development has been published since the publication of the term micro LED. This is being done. The challenge to apply micro LEDs to displays requires the development of custom microchips based on flexible materials / devices for micro-LED devices, and the accuracy of transfer and display pixel electrodes of micrometer-sized LED chips. There is a need for technology for mounting.

In particular, in connection with the transfer for transferring the micro LED device to the display substrate, as the LED size is reduced to the unit of 1-100 micrometers (μm), it is not possible to use the existing pick & place equipment, There is a need for a transfer head technology that transfers more precisely. In relation to the transfer head technology, several structures as described below have been proposed, but each proposed technology has some disadvantages.

Luxvue of the United States has proposed a method for transferring a micro LED using an electrostatic head (Public Patent Publication No. 2014-0112486, hereinafter referred to as "prior invention 1"). The transfer principle of the present invention 1 is a principle of generating adhesion between the micro LED and the charging by applying a voltage to a head part made of silicon. This method may cause a problem of micro LED damage due to a charging phenomenon due to the voltage applied to the head during the electrostatic induction.

X-Celeprint Inc. of the United States proposed a method of transferring a micro LED on a wafer to a desired substrate by applying a transfer head as an elastic polymer material (Publication Publication No. 2017-0019415, hereinafter referred to as `` Prevention 2 ''). box). This method has no problems with LED damage compared to the electrostatic head method, but it can transfer micro LEDs stably when the transfer force of the elastic transfer head is larger than the adhesive force of the target substrate, and requires an additional process for electrode formation. There are disadvantages. In addition, maintaining the adhesive strength of the elastomeric material is also a very important factor.

The Korean Institute of Optical Technology proposed a method for transferring micro LEDs using a cilia adhesive structure head (registered patent publication No. 1754528, hereinafter referred to as 'prior invention 3'). However, the preceding invention 3 has a disadvantage in that it is difficult to manufacture the adhesive structure of the cilia.

The Korea Institute of Machinery and Materials proposed a method of transferring micro LEDs by coating an adhesive on a roller (registered patent publication No. 1757404, hereinafter referred to as 'prior invention 4'). However, the present invention 4 requires the continuous use of the adhesive, and there is a disadvantage that the micro LED may be damaged when the roller is pressed.

Samsung Display proposed a method of transferring micro LEDs to an array substrate by electrostatic induction by applying a negative voltage to the first and second electrodes of the array substrate while the array substrate is in a solution. 2017-0026959, hereinafter referred to as `` First Invention 5 ''). However, the prior invention 5 has a disadvantage in that a separate solution is required in that the micro LED is transferred to the array substrate by soaking in a solution, and then a drying process is required.

LG Electronics has proposed a method of arranging a head holder between a plurality of pickup heads and a substrate and deforming its shape by the movement of the plurality of pickup heads to provide a degree of freedom to the plurality of pickup heads. -2017-0024906, hereinafter referred to as 'prior invention 6'). However, the present invention 6 is a method of transferring a micro LED by applying a bonding material having an adhesive force to the adhesive surface of the plurality of pickup heads, there is a disadvantage that a separate process for applying a bonding material to the pickup head is required.

In addition to the problems of the foregoing inventions, the prior inventions have a problem that the adsorption surface of the transfer head comes into contact with the top surface of the micro LED when the micro LED is transferred from the growth substrate to the display substrate.

In detail, when the transfer head is lowered, if the adsorption surface of the transfer head is in direct contact with the micro LED, the position of the micro LED chipped on the growth substrate is distorted, and thus a position error may occur when the transfer head is mounted on the display substrate. Furthermore, since the micro LED has a very small size, the micro LED may be broken when the adsorption surface of the transfer head and the micro LED come into contact with each other.

In addition, in the case of the conventional transfer head, there is a problem in that there is no means to compensate for the abnormality in the adsorption force by adsorbing the micro LED using one kind of adsorption force.

In order to solve the problems of the preceding inventions, the above-mentioned disadvantages should be improved while adopting the basic principles adopted by the preceding inventions. These disadvantages are derived from the basic principles adopted by the preceding inventions. There are limits to improving the shortcomings. Accordingly, the applicant of the present invention is not only to improve the disadvantages of the prior art, but to propose a new method that has not been considered in the prior inventions at all.

Registered Patent Publication No. 0731673 Published Patent Publication No. 2014-0112486 Korean Laid-Open Patent Publication No. 2017-0019415 Registered Patent Publication No. 1754528 Registered Patent Publication No. 1757404 Patent Publication No. 10-2017-0026959 Patent Publication No. 10-2017-0024906

Accordingly, the present invention is to adsorb the micro LED through the first and second adsorption force different from each other, the problem caused by the position error caused by the adsorption surface of the micro LED transfer head is in contact with the upper surface of the micro LED when the micro LED is transferred, and the micro An object of the present invention is to provide a micro LED transfer head that solves the problem of breakage of LEDs.

On the other hand, it is an object of the present invention to provide a micro LED transfer head that compensates for the poor adsorption of micro LEDs.

In order to achieve the object of the present invention, the micro LED transfer head of the present invention is a micro LED transfer head for adsorbing a micro LED, the micro LED transfer head is a micro LED through a different first and second adsorption force. It is characterized by adsorbing.

In addition, a first adsorption force generation unit provided in the lower portion of the micro LED to generate the first adsorption force; And a second adsorption force generation unit provided below the first adsorption force generation unit to form a part of the lower surface of the micro LED transfer head and generating the second adsorption force.

The apparatus may further include a blocking unit provided at a lower portion of the second adsorption force generation unit to block the generation of the second adsorption force.

In addition, the first adsorption force generated by the first adsorption force generation unit is a suction force, and the second adsorption force generated by the second adsorption force generation unit is characterized in that the electrostatic force or magnetic force.

In addition, the first adsorption force and the second adsorption force may be sequentially generated to adsorb the micro LED.

The first adsorption force supports the micro LED until the micro LED contacts the bottom surface of the micro LED transfer head, and the second adsorption force causes the micro LED to be in contact with the bottom surface of the micro LED transfer head. It is characterized by adsorbing on the lower surface of the transfer head.

The second adsorption force supports the micro LED until the micro LED contacts the bottom surface of the micro LED transfer head, and the first adsorption force causes the micro LED to be in contact with the bottom surface of the micro LED transfer head. It is characterized by adsorbing on the lower surface of the transfer head.

In addition, the first adsorption force and the second adsorption force may be simultaneously generated to adsorb the micro LED.

Micro LED transfer head of the present invention having another feature, a micro LED transfer head for absorbing the micro LED, the first adsorption force generating unit is provided in the lower portion of the micro LED to generate the first adsorption force; And a second adsorption force generation unit provided below the first adsorption force generation unit to form part of a lower surface of the micro LED transfer head and generating the second adsorption force, wherein the micro LED transfer heads are different from each other. The micro LED is adsorbed through the adsorption force and the second adsorption force, and the first adsorption force generating unit is provided with a hole to generate a suction force that is the first adsorption force through the hole, and the second adsorption force generating unit is provided with an electrode layer and a dielectric layer. The electrostatic force as the second adsorption force is generated through the electrode layer and the dielectric layer, or the magnetic force layer is provided at the second adsorption force generation unit to generate the magnetic force as the second adsorption force through the magnetic force layer.

In addition, the electrode layer, the dielectric layer or the magnetic force layer is characterized in that located below the region where the hole is not formed.

As described above, the micro LED transfer head according to the present invention has the following effects.

It is possible to prevent damage or breakage of the micro LED caused by the manner in which the micro LED transfer head descends to contact the upper surface of the micro LED, and to solve the position error problem occurring when the micro LED is absorbed.

If the adsorption force of any one of the first and second adsorption forces has a force so weak that it cannot support or adsorb at least one of the plurality of micro LEDs, or cannot support or adsorb, the other force compensates for this. The plurality of micro LEDs can be easily adsorbed to the lower surface of the micro LED transfer head.

1 is a view showing a micro LED to be transferred in the embodiment of the present invention.
FIG. 2 is a view of a micro LED structure that is transferred to and mounted on a display substrate according to an embodiment of the present invention. FIG.
3 is a view of a micro LED transfer head according to a first embodiment of the present invention.
4A to 4D illustrate a process of absorbing micro LEDs using the micro LED transfer head of FIG. 3.
5 is a view showing that the micro LED is adsorbed on the micro LED transfer head according to a second embodiment of the present invention.
6 is a view showing that the micro LED is adsorbed to the micro LED transfer head according to a third embodiment of the present invention.
7 is a view showing that the micro LED is adsorbed on the micro LED transfer head according to a fourth embodiment of the present invention.
8 is a view showing that the micro LED is adsorbed on the micro LED transfer head according to a fifth embodiment of the present invention.

The following merely illustrates the principles of the invention. Therefore, those skilled in the art may implement the principles of the invention and invent various devices included in the concept and scope of the invention, although not explicitly described or illustrated herein. In addition, all conditional terms and embodiments listed herein are in principle clearly intended to be understood only for the purpose of understanding the concept of the invention and are not to be limited to the specifically listed embodiments and states. .

The above objects, features, and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, and thus, it will be possible to easily implement the technical idea of self-invention having ordinary skill in the art. .

Embodiments described herein will be described with reference to cross-sectional and / or perspective views, which are ideal exemplary views of the invention. The thicknesses of the films and regions and the diameters of the holes shown in these figures are exaggerated for the effective explanation of the technical contents. The shape of the exemplary diagram may be modified by manufacturing techniques and / or tolerances. In addition, the number of micro-LEDs shown in the drawings is only a part of the drawings for illustrative purposes. Accordingly, the embodiments of the present invention are not limited to the specific forms shown, but also include changes in forms generated according to manufacturing processes.

In various embodiments of the present disclosure, components that perform the same function will be given the same names and the same reference numbers for convenience, even though the embodiments are different. In addition, the configuration and operation already described in other embodiments will be omitted for convenience.

Before the description, the following items are defined. The micro LED transfer heads 1000 to 1000d are provided with an adsorption area A and a non-adsorption area B. In this case, the adsorption area A means an area for adsorbing the micro LED 100 and is non-adsorption. The area B means an area that does not adsorb the micro LED 100.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a micro LED to be transferred in the embodiment of the present invention.

The micro LED 100 is fabricated and positioned on the growth substrate 101.

The growth substrate 101 may be made of a conductive substrate or an insulating substrate. For example, the growth substrate 101 may be formed of at least one of sapphire, SiC, Si, GaAs, GaN, ZnO, Si, GaP, InP, Ge, and Ga ₂ O ₃ .

The micro LED 100 may include a first semiconductor layer 102, a second semiconductor layer 104, an active layer 103 formed between the first semiconductor layer 102 and the second semiconductor layer 104, and a first contact electrode ( 106 and a second contact electrode 107.

The first semiconductor layer 102, the active layer 103, and the second semiconductor layer 104 may be formed of metal organic chemical vapor deposition (MOCVD), chemical vapor deposition (CVD), or plasma chemical vapor deposition (CVD). Plasma-Enhanced Chemical Vapor Deposition (PECVD), Molecular Beam Epitaxy (MBE), Hydride Vapor Phase Epitaxy (HVPE), or the like.

The first semiconductor layer 102 may be implemented with, for example, a p-type semiconductor layer. The p-type semiconductor layer is a semiconductor material having a composition formula of InxAlyGa1-x-yN (0≤x≤1, 0≤y≤1, 0≤x + y≤1), for example, GaN, AlN, AlGaN, InGaN, InN , InAlGaN, AlInN, and the like, and p-type dopants such as Mg, Zn, Ca, Sr, and Ba may be doped.

The second semiconductor layer 104 may be formed, for example, including an n-type semiconductor layer. The n-type semiconductor layer is a semiconductor material having a composition formula of InxAlyGa1-x-yN (0≤x≤1, 0≤y≤1, 0≤x + y≤1), for example, GaN, AlN, AlGaN, InGaN, InNInAlGaN , AlInN, and the like, and n-type dopants such as Si, Ge, Sn, and the like may be doped.

However, the present invention is not limited thereto, and the first semiconductor layer 102 may include an n-type semiconductor layer, and the second semiconductor layer 104 may include a p-type semiconductor layer.

The active layer 103 is a region where electrons and holes are recombined. The active layer 103 may transition to a low energy level as the electrons and holes recombine, and may generate light having a corresponding wavelength. The active layer 103 may include, for example, a semiconductor material having a compositional formula of InxAlyGa1-x-yN (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1), and It may be formed of a quantum well structure or a multi quantum well structure (MQW). In addition, a quantum wire structure or a quantum dot structure may be included.

The first contact electrode 106 may be formed on the first semiconductor layer 102, and the second contact electrode 107 may be formed on the second semiconductor layer 104. The first contact electrode 106 and / or the second contact electrode 107 may comprise one or more layers and may be formed of various conductive materials including metals, conductive oxides and conductive polymers.

The plurality of micro LEDs 100 formed on the growth substrate 101 are cut along the cutting line using a laser or the like, or separately separated by an etching process, and the plurality of micro LEDs 100 are separated by the laser lift-off process. It can be made to be in a state detachable from 101.

In Figure 1 'p' means the pitch interval between the micro LED 100, 's' means the separation distance between the micro LED 100, 'w' means the width of the micro LED (100).

2 is a view of a micro LED structure is transferred to the display substrate and mounted in accordance with an embodiment of the present invention.

The display substrate 301 may include various materials. For example, the display substrate 301 may be made of a transparent glass material mainly containing SiO ₂ . However, the display substrate 301 is not necessarily limited thereto, and may be formed of a transparent plastic material to have solubility. Plastic materials include insulating polyethersulphone (PES), polyacrylate (PAR, polyacrylate), polyetherimide (PEI), polyethylene naphthalate (PEN, polyethyelenen napthalate), polyethylene terephthalate (PET) polyethyeleneterepthalate, polyphenylene sulfide (PPS), polyallylate, polyimide, polycarbonate (PC), cellulose tri acetate (TAC), cellulose acetate propionate: CAP) may be an organic material selected from the group consisting of.

When the image is a bottom emission type implemented in the direction of the display substrate 301, the display substrate 301 should be formed of a transparent material. However, when the image is a top emission type implemented in a direction opposite to the display substrate 301, the display substrate 301 does not necessarily need to be formed of a transparent material. In this case, the display substrate 301 may be formed of metal.

When the display substrate 301 is formed of metal, the display substrate 301 may be at least one selected from the group consisting of iron, chromium, manganese, nickel, titanium, molybdenum, stainless steel (SUS), Invar alloy, Inconel alloy, and Kovar alloy. It may include, but is not limited thereto.

The display substrate 301 may include a buffer layer 311. The buffer layer 311 may provide a flat surface and may block foreign matter or moisture from penetrating. For example, the buffer layer 311 may be formed of inorganic materials such as silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, titanium oxide, or titanium nitride, or organic materials such as polyimide, polyester, and acryl. And may be formed of a plurality of laminates of the illustrated materials.

The thin film transistor TFT may include an active layer 310, a gate electrode 320, a source electrode 330a, and a drain electrode 330b.

Hereinafter, the thin film transistor TFT will be described as a top gate type in which the active layer 310, the gate electrode 320, the source electrode 330a, and the drain electrode 330b are sequentially formed. However, the present exemplary embodiment is not limited thereto, and various types of thin film transistors (TFTs), such as a bottom gate type, may be employed.

The active layer 310 may include a semiconductor material, for example, amorphous silicon or poly crystalline silicon. However, the present embodiment is not limited thereto, and the active layer 310 may contain various materials. In some embodiments, the active layer 310 may contain an organic semiconductor material.

In another alternative embodiment, the active layer 310 may contain an oxide semiconductor material. For example, the active layer 310 may be formed of Group 12, 13, 14 metal elements such as zinc (Zn), indium (In), gallium (Ga), tin (Sn) cadmium (Cd), germanium (Ge), and combinations thereof. Oxides of the selected materials.

A gate insulating layer 313 is formed on the active layer 310. The gate insulating layer 313 insulates the active layer 310 and the gate electrode 320. The gate insulating layer 313 may be formed of a multilayer or a single layer formed of an inorganic material such as silicon oxide and / or silicon nitride.

The gate electrode 320 is formed on the gate insulating layer 313. The gate electrode 320 may be connected to a gate line (not shown) for applying an on / off signal to the thin film transistor TFT.

The gate electrode 320 may be made of a low resistance metal material. The gate electrode 320 is made of aluminum (Al), platinum (Pt), palladium (Pd), silver (Ag), magnesium (Mg) in consideration of adhesion to adjacent layers, surface flatness of the stacked layers, and workability. , Gold (Au), Nickel (Ni), Neodymium (Nd), Iridium (Ir), Chromium (Cr), Lithium (Li), Calcium (Ca), Molybdenum (Mo), Titanium (Ti), Tungsten (W) It may be formed of a single layer or multiple layers of one or more materials of copper (Cu).

An interlayer insulating layer 315 is formed on the gate electrode 320. The interlayer insulating layer 315 insulates the source electrode 330a, the drain electrode 330b, and the gate electrode 320. The interlayer insulating film 315 may be formed of a multilayer or a single layer of an inorganic material. For example, the inorganic material may be a metal oxide or a metal nitride. Specifically, the inorganic material may be silicon oxide (SiO ₂ ), silicon nitride (SiNx), silicon oxynitride (SiON), aluminum oxide (Al ₂ O ₃ ), or titanium oxide ( TiO ₂ ), tantalum oxide (Ta ₂ O ₅ ), hafnium oxide (HfO ₂ ), zinc oxide (ZrO ₂ ), and the like.

The source electrode 330a and the drain electrode 330b are formed on the interlayer insulating film 315. The source electrode 330a and the drain electrode 330b include aluminum (Al), platinum (Pt), palladium (Pd), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni), and neodymium (Nd). ), Iridium (Ir), chromium (Cr), lithium (Li), calcium (Ca), molybdenum (Mo), titanium (Ti), tungsten (W), copper (Cu) of one or more materials Can be formed. The source electrode 330a and the drain electrode 330b are electrically connected to the source region and the drain region of the active layer 310, respectively.

The planarization layer 317 is formed on the thin film transistor TFT. The planarization layer 317 is formed to cover the thin film transistor TFT, thereby eliminating a step resulting from the thin film transistor TFT and making the top surface flat. The planarization layer 317 may be formed of a single layer or multiple layers of an organic material. Organic materials include general purpose polymers such as polymethylmethacrylate (PMMA) and polystylene (PS), polymer derivatives having phenolic groups, acrylic polymers, imide polymers, arylether polymers, amide polymers, fluorine polymers, and p-xylene Polymers, vinyl alcohol-based polymers and blends thereof, and the like. In addition, the planarization layer 317 may be formed of a composite laminate of an inorganic insulating film and an organic insulating film.

The first electrode 510 is positioned on the planarization layer 317. The first electrode 510 may be electrically connected to the thin film transistor TFT. In detail, the first electrode 510 may be electrically connected to the drain electrode 330b through a contact hole formed in the planarization layer 317. The first electrode 510 may have various shapes. For example, the first electrode 510 may be patterned in an island shape. The bank layer 400 defining the pixel region may be disposed on the planarization layer 317. The bank layer 400 may include a recess in which the micro LED 100 is to be accommodated. For example, the bank layer 400 may include a first bank layer 410 forming a recess. The height of the first bank layer 410 may be determined by the height and viewing angle of the micro LED 100. The size (width) of the recess may be determined by the resolution, the pixel density, and the like of the display device. In an embodiment, the height of the micro LED 100 may be greater than the height of the first bank layer 410. The concave portion may have a rectangular cross-sectional shape, but embodiments of the present disclosure are not limited thereto, and the concave portion may have various cross-sectional shapes such as polygons, rectangles, circles, cones, ellipses, and triangles.

The bank layer 400 may further include a second bank layer 420 on the first bank layer 410. The first bank layer 410 and the second bank layer 420 may have steps, and the width of the second bank layer 420 may be smaller than that of the first bank layer 410. The conductive layer 550 may be disposed on the second bank layer 420. The conductive layer 550 may be disposed in a direction parallel to the data line or the scan line and electrically connected to the second electrode 530. However, the present invention is not limited thereto, and the second bank layer 420 may be omitted, and the conductive layer 550 may be disposed on the first bank layer 410. Alternatively, the second bank layer 420 and the conductive layer 500 may be omitted, and the second electrode 530 may be formed on the entire substrate 301 as a common electrode common to the pixels P. The first bank layer 410 and the second bank layer 420 may include a material that absorbs at least a portion of light, a light reflecting material, or a light scattering material. The first bank layer 410 and the second bank layer 420 may include an insulating material that is translucent or opaque to visible light (eg, light in a wavelength range of 380 nm to 750 nm).

For example, the first bank layer 410 and the second bank layer 420 may be polycarbonate (PC), polyethylene terephthalate (PET), polyether sulfone, polyvinyl butyral, polyphenylene ether, polyamide, poly Thermoplastic resins such as etherimide, norbornene system resins, methacryl resins, cyclic polyolefins, epoxy resins, phenol resins, urethane resins, acrylic resins, vinyl ester resins, imide resins, urethane resins, and urea It may be formed of a thermosetting resin such as resin, melamine resin, or an organic insulating material such as polystyrene, polyacrylonitrile, polycarbonate, but is not limited thereto.

As another example, the first bank layer 410 and the second bank layer 420 may be formed of an inorganic insulating material such as inorganic oxides, inorganic nitrides, such as SiOx, SiNx, SiNxOy, AlOx, TiOx, TaOx, ZnOx, It is not limited to this. In one embodiment, the first bank layer 410 and the second bank layer 420 may be formed of an opaque material such as a black matrix material. Insulating black matrix materials include organic resins, resins or pastes comprising glass paste and black pigments, metal particles such as nickel, aluminum, molybdenum and alloys thereof, metal oxide particles (eg chromium oxide), Or metal nitride particles (eg, chromium nitride) or the like. In a modified example, the first bank layer 410 and the second bank layer 420 may be distributed Bragg reflectors (DBR) having a high reflectance or mirror reflectors formed of a metal.

The micro LED 100 is disposed in the recess. The micro LED 100 may be electrically connected to the first electrode 510 in the recess.

The micro LED 100 emits light having a wavelength of red, green, blue, white, and the like, and white light may be realized by using a fluorescent material or combining colors. The micro LED 100 has a size of 1 μm to 100 μm. Each of the micro LEDs 100 is picked up on the growth substrate 101 by a transfer head according to an exemplary embodiment of the present invention, or transferred to the display substrate 301 by a transfer head according to an exemplary embodiment of the present invention. Can be accommodated in

The micro LED 100 includes a p-n diode, a first contact electrode 106 disposed on one side of the p-n diode, and a second contact electrode 107 positioned on the opposite side to the first contact electrode 106. The first contact electrode 106 may be connected to the first electrode 510, and the second contact electrode 107 may be connected to the second electrode 530.

The first electrode 510 may include a reflective film formed of Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, or a compound thereof, and a transparent or translucent electrode layer formed on the reflective film. The transparent or translucent electrode layer may be formed of indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium oxide (In ₂ O _3, indium oxide), and indium gallium. At least one selected from the group consisting of oxide (IGO; indium gallium oxide) and aluminum zinc oxide (AZO) may be provided.

The passivation layer 520 surrounds the micro LED 100 in the recess. The passivation layer 520 fills the space between the bank layer 400 and the micro LED 100 to cover the recess and the first electrode 510. The passivation layer 520 may be formed of an organic insulating material. For example, the passivation layer 520 may be formed of acrylic, poly (methyl methacrylate) (PMMA), benzocyclobutene (BCB), polyimide, acrylate, epoxy, polyester, and the like, but is not limited thereto. It is not.

The passivation layer 520 is formed above the micro LED 100, for example, at a height not covering the second contact electrode 107, so that the second contact electrode 107 is exposed. A second electrode 530 electrically connected to the exposed second contact electrode 107 of the micro LED 100 may be formed on the passivation layer 520.

The second electrode 530 may be disposed on the micro LED 100 and the passivation layer 520. The second electrode 530 may be formed of a transparent conductive material such as ITO, IZO, ZnO, or In ₂ O ₃ .

Micro LED transfer head 1000 according to the first embodiment of the present invention

Hereinafter, the micro LED transfer head 1000 according to the first embodiment of the present invention will be described with reference to FIGS. 3 to 4D.

3 is a view of a micro LED transfer head according to a first embodiment of the present invention, Figures 4a to 4d is a view showing a process of adsorbing the micro LED using the micro LED transfer head of FIG.

3 to 4D, the micro LED transfer head 1000 according to the first exemplary embodiment of the present invention adsorbs the micro LED 100 through different first and second adsorption forces. The first adsorption force generating unit 1100 is provided below the micro LED transfer head 1000 to generate a first adsorption force, and is provided below the first adsorption force generating unit 1100 of the micro LED transfer head 1000. A portion of the lower surface, the second adsorption force generating unit 1300 for generating a second adsorption force, and the blocking unit 1500 provided in the lower portion of the second adsorption force generating unit 1300 to block the generation of the second adsorption force It can be configured to include.

The first adsorption force generating unit 1100 generates a first adsorption force and is provided on an upper portion of the second adsorption force generating unit 1300 at the bottom of the micro LED transfer head 1000.

The first adsorption force is a different kind of force from the second adsorption force, that is, a heterogeneous force. In a first preferred embodiment of the present invention, the first adsorption force may be a suction force.

The first adsorption force generating unit 1100 may include a base material 1110 and a plurality of holes 1130 provided in the base material 1110.

The plurality of holes 1130 may be formed in the base material 1110 through etching or laser processing.

The plurality of holes 1130 communicate with the chamber 1010 of the micro LED transfer head 1000.

The chamber 1010 means a space above the first adsorption force generating unit 1100 of the micro LED transfer head 1000, and the chamber 1010 is in communication with an external pumping device (not shown). According to the structure as described above, when the external pumping device is operated, the suction force is generated in the plurality of holes 1130 of the chamber 1010 and the first suction force generating unit 1100, this suction force prevents the adsorption of the micro LED (100). It is the first adsorption force to achieve.

As shown in FIGS. 3 to 4D, one hole 1130 may be formed in one adsorption area A. As shown in FIGS. 3 to 4D, one adsorption area A may be formed. A plurality of holes 1130 may be formed in the hole.

The second adsorption force generator 1300 generates a second adsorption force and is provided below the first adsorption force generator 1100.

The second adsorption force is a kind of force different from the first adsorption force, that is, a heterogeneous force. In the first preferred embodiment of the present invention, the second adsorption force may be an electrostatic force or a magnetic force.

The second adsorption force generating unit 1300 may include an upper layer 1310 formed on the lower surface of the first adsorption force generating unit 1100 and a lower layer 1330 provided on the lower surface of the lower layer 1330.

In this case, the upper layer 1310 and the lower layer 1330 are positioned below the region where the hole 1130 of the first adsorption force generating unit 1100 is not formed. Therefore, the second adsorption force generating unit 1300 is positioned below the region where the hole 1130 of the first adsorption force generating unit 1100 is not formed.

When the second adsorption force is an electrostatic force, the upper layer 1310 may be an electrode layer, and the lower layer 1330 may be a dielectric layer formed on the bottom surface of the electrode layer.

A voltage is applied to the electrode layer, and when voltage is applied to the electrode layer, dielectric polarization occurs in the dielectric layer, thereby generating an electrostatic force. In this case, the electrostatic force is the second adsorption force.

The electrode layer may be a metal material such as tungsten (W) or copper (Cu), and the dielectric layer may be formed by thermally coating a ceramic material or the like on the lower surface of the electrode layer.

When the second adsorption force is a magnetic force, the upper layer 1310 may be a magnetic force layer, and the lower layer 1330 may be a protective layer formed on the lower surface of the magnetic force layer.

Voltage is applied to the magnetic force layer, and when a voltage is applied to the magnetic force layer, magnetic force is generated in the magnetic force layer. In this case, the magnetic force is the second adsorption force. The protective layer functions to protect the magnetic force layer and to prevent the top surface of the micro LED 100 from being damaged by the magnetic force layer. In addition, the aforementioned magnetic force is a concept including an electromagnetic force.

The blocking unit 1500 is provided below the second adsorption force generating unit 1300 and functions to block the generation of the second adsorption force.

The blocking unit 1500 may be formed at a position corresponding to the non-adsorption area B on the bottom surface of the lower layer 1330 of the second adsorption force generating unit 1300.

When the second adsorption force is an electrostatic force, the blocking unit 1500 may be formed at a position corresponding to the non-adsorption region B on the lower layer 1330, that is, the lower surface of the dielectric layer, and may be formed of a material that blocks the electrostatic force. Can be.

Although the electrostatic force is generated by the electrode layer and the dielectric layer of the second adsorption force generating unit 1300, the electrostatic force is not generated in the non-adsorption region B in which the blocking unit 1500 is located. Therefore, it is possible to prevent the micro LED 100 from being adsorbed to the non-adsorption area B by the electrostatic force as the second adsorption force.

When the second adsorption force is a magnetic force, the blocking unit 1500 may be formed at a position corresponding to the non-adsorption area B on the lower layer 1330, that is, the protective layer, and may be made of a material that blocks the magnetic force. Can be done. If the lower layer 1330, that is, the protective layer is not provided in the second adsorption force generating unit 1300, the blocking unit 1500 may be formed on the lower surface of the upper layer 1310, that is, the magnetic force layer. .

Although magnetic force is generated by the magnetic force layer of the second suction force generating unit 1300, the magnetic force is not generated in the non-adsorption area B in which the blocking unit 1500 is located. Therefore, it is possible to prevent the micro LED 100 from being adsorbed to the non-adsorption area B by the magnetic force, which is the second adsorption force.

Hereinafter, a method of adsorbing the micro LED 100 through the micro LED transfer head 1000 according to the first embodiment of the present invention having the above-described configuration will be described.

The method of adsorbing the micro LED 100 can be divided into two types.

The first method is a method of adsorbing the micro LED 100 by generating the first adsorption force and the second adsorption force sequentially, and the second method is a method of adsorbing the micro LED 100 by simultaneously generating the first adsorption force and the second adsorption force. .

Hereinafter, referring to FIGS. 4A to 4D, a method of adsorbing the micro LED 100 by sequentially generating the first adsorption force and the second adsorption force will be described.

In order to adsorb the micro LED 100, the micro LED transfer head 1000 is positioned above the growth substrate 101, as shown in FIG. 4A. In this case, the micro LED transfer head 1000 is aligned such that the adsorption region A and the micro LED 100 are located on the same line in the vertical direction.

The micro LED transfer head 1000 aligned above the growth substrate 101 is lowered toward the growth substrate 101, as shown in FIG. 4B. In this case, the lowering of the micro LED transfer head 1000 is a lower surface of the micro LED transfer head 1000, that is, the lower layer 1330 of the second adsorption force generating unit 1300 is predetermined between the upper surface of the micro LED 100. Descend to form a separation distance.

After the micro LED 100 is lowered, as shown in FIG. 4C, the force of any one of the first adsorption force by the first adsorption force generator 1100 and the second adsorption force by the second adsorption force generator 1300. As a result, the micro LED 100 is supported in the lower surface direction of the micro LED transfer head 1000. In this case, the micro LED 100 may be supported by the force of any one of the first and second adsorption forces until the micro LED 100 contacts the bottom surface of the micro LED transfer head 1000.

After the micro LED 100 is supported by the lower surface of the micro LED transfer head 1000, as shown in Figure 4c, the first and second adsorption force generated by the first adsorption force generation unit 1100 and the second adsorption force generation unit 1300 As the other one of the second adsorption force is generated by the force, the micro LED 100 is more firmly adsorbed to the adsorption area (A) of the lower surface of the micro LED transfer head 1000.

As described above, the first adsorption force and the second adsorption force sequentially generated method, any one of the first and second adsorption force is generated first to support the micro LED 100, and then the first adsorption force and This is performed by firmly adsorbing the micro LED 100 with the remaining force of the second adsorption force to the adsorption region A of the lower surface of the micro LED transfer head 1000.

As described above, the micro LED transfer head 1000 to support the micro LED 100 by the force of any one of the first and second adsorption force, the micro-supported by the force of the other of the first and second adsorption force. Adsorb the LED 100. In other words, by not adopting the conventional method in which the micro LED transfer head 1000 descends and contacts the upper surface of the micro LED 100, the conventional problem that the micro LED 100 is damaged or broken can be effectively solved. . In addition, the position error of the micro LED 100 caused by the way that the micro LED transfer head 1000 is lowered to contact the upper surface of the micro LED 100 can be solved.

When the first suction force, that is, the suction force is generated first through the first suction force generating unit 1100, the suction force is generated through the hole 1130 by the external pumping device in the state of FIG. 4C. The LED 100 is suspended in the lower surface direction of the micro LED transfer head 1000. Thereafter, in the state of FIG. 4D, the second adsorption force is generated through the second adsorption force generating unit 1300, thereby firmly adsorbing the micro LED 100 to the adsorption region A of the lower surface of the micro LED transfer head 1000. . In other words, the first adsorption force supports the micro LED 100 until the micro LED 100 contacts the bottom surface of the micro LED transfer head 1000, and the second adsorption force is applied to the bottom surface of the micro LED transfer head 1000. The contacted micro LED 100 is adsorbed on the bottom surface of the micro LED transfer head 1000.

In this case, the second adsorption force may be an electrostatic force or a magnetic force. As such, when the first adsorption force occurs first, the suction force is a relatively strong force, and thus, even if the micro LED transfer head 1000 does not descend much, there is an advantage of easily supporting the micro LED 100. Since the adsorption force, that is, the electrostatic force or the magnetic force only needs to absorb the micro LED 100 in contact with the bottom surface of the micro LED transfer head 1000, there is an advantage that no strong force or magnetic force is required.

When the second adsorption force, that is, the electrostatic force or the magnetic force is first generated through the second adsorption force generating unit 1300, the electrostatic force is generated through the electrode layer and the dielectric layer in the state of FIG. 4C, or the magnetic force is generated through the magnetic force layer. By the electrostatic force or magnetic force, the micro LED 100 is supported in the lower surface direction of the micro LED transfer head 1000. Subsequently, in the state of FIG. 4D, a first adsorption force, that is, a suction force is generated through the hole 1130 of the first adsorption force generation unit 1100 to adsorb the micro LED 100 in the lower surface of the micro LED transfer head 1000. The area A is firmly adsorbed. In other words, the second adsorption force supports the micro LED 100 until the micro LED 100 contacts the bottom surface of the micro LED transfer head 1000, and the first adsorption force is applied to the bottom surface of the micro LED transfer head 1000. The contacted micro LED 100 is adsorbed on the bottom surface of the micro LED transfer head 1000.

As such, when the second adsorption force occurs first, after the micro LED 100 supported by the second adsorption force, that is, the electrostatic force or the magnetic force contacts the lower surface of the micro LED transfer head 1000, Since the upper surface of the micro LED 100 is sucked by the suction force, a vacuum pressure (or negative pressure) is generated between the upper surface of the micro LED 100 and the hole, so that the micro LED 100 can be absorbed with a stronger force. There is an advantage.

In addition, the micro LED transfer head 1000 according to the first embodiment of the present invention having the above-described configuration has the following effects.

As described above, the micro LED transfer head 1000 according to the first embodiment of the present invention may generate the first adsorption force and the second adsorption force at the same time to adsorb the micro LED 100. In other words, after the micro LED transfer head 1000 is lowered while forming a separation distance on the growth substrate 101, each of the first adsorption force generating unit 1100 and the second adsorption force generating unit 1300 may be formed. By generating the first adsorption force and the second adsorption force, the micro LED 100 is adsorbed on the lower surface of the micro LED transfer head 1000.

As described above, when the first and second adsorption forces are generated at the same time, any one of the adsorption forces may have a weak force so as not to support or adsorb at least one of the plurality of micro LEDs 100 or the first adsorption force generator ( If it cannot be supported or adsorbed due to the failure of the 1100 or the second adsorption force generating unit 1300, the remaining one compensates for this, and thus all of the plurality of micro LEDs 100 of the growth substrate 101 are micro LEDs. The lower surface of the transfer head 1000 can be easily adsorbed.

Although the above described the adsorption process of the micro LED transfer head 1000 based on the adsorption of the micro LED 100 seated on the growth substrate 101, the above process even when the micro LED 100 is on a temporary substrate or the like. Can be applied.

Hereinafter, the micro LED transfer heads 1000a to 1000d according to the second to fifth embodiments of the present invention will be described. However, embodiments described below will be described based on the characteristic elements compared to the above-described first embodiment, and descriptions of the same or similar elements as the first embodiment will be omitted.

Micro LED transfer head 1000a according to a second embodiment of the present invention

Hereinafter, the micro LED transfer head 1000a according to the second exemplary embodiment of the present invention will be described with reference to FIG. 5.

5 is a view showing that the micro LED is adsorbed to the micro LED transfer head according to a second embodiment of the present invention.

The micro LED transfer head 1000a according to the second exemplary embodiment of the present invention has a shape in which the width of the blocking portion 1500a becomes smaller from the bottom to the top. In other words, the blocking portion 1500a has a shape in which the width of the lower surface is smaller than the width of the upper surface.

Due to the shape of the blocking unit 1500a as described above, when the micro LED 100 is adsorbed to the adsorption area A of the micro LED transfer head 1000a, the suspended micro LED 100 is guided to guide the micro LED 100. Since it is lifted in the lower direction, its position can be aligned and adsorbed. Therefore, it is possible to effectively prevent the position error of the micro LED 100 is generated and adsorbed.

Micro LED transfer head 1000b according to a third embodiment of the present invention

Hereinafter, the micro LED transfer head 1000b according to the third exemplary embodiment of the present invention will be described with reference to FIG. 6.

6 is a view showing that the micro LED is adsorbed to the micro LED transfer head according to a third embodiment of the present invention.

The micro LED transfer head 1000b according to the third exemplary embodiment of the present invention may further include a porous ceramic 1700 having a plurality of pores on the first adsorption force generating unit 1100. In this case, the plurality of pores communicate with the hole 1130.

Therefore, the suction force, which is the first suction force, may be generated through the holes 1130 of the plurality of pores and the first suction force generator 1100.

As described above, as the porous ceramic 1700 is provided on the upper portion of the first adsorption force generating unit 1100, the solid support of the first adsorption force generating unit 1100 is achieved, and a plurality of pores and holes 1130 communicate with each other. By means of easy generation of suction force can be achieved.

Micro LED transfer head 1000c according to a fourth embodiment of the present invention

Hereinafter, the micro LED transfer head 1000c according to the fourth exemplary embodiment of the present invention will be described with reference to FIG. 7.

7 is a view showing that the micro LED is adsorbed to the micro LED transfer head according to a fourth embodiment of the present invention.

The micro LED transfer head 1000b according to the third exemplary embodiment of the present invention is characterized in that the first adsorption force generating unit 1100c is made of an anodized film having a plurality of holes 1130c.

The anodization film refers to a film formed by anodizing a metal as a base material, and the hole 1130c refers to a hole formed in a process of forming an anodization film by anodizing a metal.

For example, when the base metal is aluminum (Al) or an aluminum alloy, when the base material is anodized, an anodized film made of anodized aluminum (Al ₂ O ₃ ) is formed on the surface of the base material.

As described above, the formed anodization film is divided into a barrier layer in which holes 1130c are not formed and a porous layer in which holes 1130c are formed.

The barrier layer is located on top of the base material, and the porous layer is located on top of the barrier layer.

As such, when the base material is removed from the base material on which the anodization film having the barrier layer and the porous layer is formed on the surface, only the anodization film made of anodized aluminum (Al ₂ O ₃ ) material remains.

The anodic oxide film has a hole 1130c having a regular arrangement while having a uniform diameter and a vertical shape.

Therefore, when the barrier layer is removed, the hole 1130c has a structure vertically penetrated up and down, thereby making it easy to form a vacuum pressure in the vertical direction.

The inside of the anodic oxide film can form an air flow path in a vertical shape by the vertical hole 1130c.

The inner width of the aperture 1130c has a size of several nm to several hundred nm. For example, when the size of the micro LED to be vacuum absorbed is 30 μm × 30 μm and the inner width of the hole 1130 c is several nm, the micro LED 100 may be formed using about tens of millions of holes 1130 c. Can be adsorbed in vacuum. On the other hand, when the size of the micro LED to be vacuum absorbed is 30 μm × 30 μm and the inner width of the hole 1130 c is several hundred nm, the micro LED 100 is used by using tens of thousands of holes 1130 c. The vacuum adsorption becomes possible.

In the case of the micro LED 100, basically, the first semiconductor layer 102, the second semiconductor layer 104, the active layer 103 formed between the first semiconductor layer 102 and the second semiconductor layer 104, Since only the first contact electrode 106 and the second contact electrode 107 are relatively light, vacuum adsorption is possible using tens of thousands to tens of millions of holes 1130c of the anodization film.

When the first adsorption force generating unit 1100c is made of an anodized film, the upper layer 1310 and the lower layer 1330 of the second adsorption force generating unit 1300 correspond to a region where the hole 1130c of the anodizing film is not formed. It can be formed at the position.

When the first adsorption force generating part 1000c of the micro LED transfer head 1000c according to the fourth exemplary embodiment of the present invention is formed of an anodized film having a plurality of holes 1130c, when the suction force that is the first adsorption force occurs. In addition, there is an advantage that the micro LED 100 having a tens of μm size can be supported or adsorbed more effectively.

Micro LED transfer head (1000d) according to a fifth embodiment of the present invention

Hereinafter, a micro LED transfer head 1000c according to a fourth exemplary embodiment of the present invention will be described with reference to FIG. 8.

7 is a view showing that the micro LED is adsorbed to the micro LED transfer head according to a fourth embodiment of the present invention.

In the micro LED transfer head 1000b according to the fourth embodiment of the present invention, the first adsorption force generating unit 1100c is formed of an anodized film having a plurality of holes 1130c, and the first adsorption force generating unit 1100c is provided. It is characterized in that it further comprises a porous ceramic (1700) having a plurality of pores on the top. In this case, the plurality of pores communicate with the hole 1130c.

Therefore, the suction force, which is the first suction force, may be generated through the holes 1130c of the plurality of pores and the first suction force generator 1100c.

As described above, as the porous ceramic 1700 is provided on the upper portion of the first adsorption force generating unit 1100c made of an anodized film, solid support of the first adsorption force generating unit 1100c is achieved and a plurality of pores and holes ( The generation of easy suction force can be achieved by the communication of 1130c).

The first adsorption force and the second adsorption force of the micro LED transfer head may be made of a combination of other forces, unlike the above embodiments.

In other words, the first adsorption force may be any one of electrostatic force, magnetic force, suction force, van der Waals force, and adhesive force, and the second adsorption force may be the other one of the forces.

As one example, when the micro LED 100 is supported by the first adsorption force and the micro LED 100 supported by the second adsorption force is adsorbed to the lower surface of the micro LED transfer head, the first adsorption force may be electrostatic force, magnetic force, Any one of suction force and van der Waals force, and the second suction force may be adhesive force.

Therefore, the micro LED 100 is supported by any one of the first adsorption force, electrostatic force, magnetic force, suction force, van der Waals force, and can be firmly adsorbed to the lower surface of the micro LED transfer head by the adhesive force as the second adsorption force. .

As described above, when the micro LED 100 is finally adsorbed to the lower surface of the micro LED transfer head by the adhesive force, the lower surface of the micro LED transfer head is provided by a stronger adhesive force than the adhesive force on the substrate to which the micro LED 100 is transferred. The micro LED 100 adsorbed on the can be easily transferred.

As described above, although described with reference to preferred embodiments of the present invention, those skilled in the art various modifications of the present invention without departing from the spirit and scope of the invention described in the claims below. Or it may be modified.

100: micro LED 101: growth substrate
102: first semiconductor layer 130: active layer
104: second semiconductor layer 106: first contact electrode
107: second contact electrode 301: display substrate
310: active layer 311: buffer layer
313: gate insulating film 315: interlayer insulating film
317: planarization layer 320: gate electrode
330a: source electrode 330b: drain electrode
400: bank layer 410: first bank layer
420: second bank layer 510: first electrode
520: passivation layer 530: second electrode
550: conductive layer
1000, 1000a, 1000b, 1000c, 1000d: micro LED transfer head
1010: chamber 1100, 1100c: first adsorption force generating unit
1110: substrate 1130, 1130c: hole
1300: the second adsorption force generating unit 1310: the upper layer
1330: lower layer 1500: blocking part
1700: porous ceramic
A: adsorption zone B: non-adsorption zone

Claims (10)

As a micro LED transfer head that absorbs micro LED,
The micro LED transfer head is a micro LED transfer head, characterized in that for adsorbing the micro LED through different first and second adsorption force. The method of claim 1,
A first adsorption force generation unit provided under the micro LED to generate the first adsorption force; And
And a second adsorption force generation unit provided under the first adsorption force generation unit to form part of a lower surface of the micro LED transfer head and generating the second adsorption force. The method of claim 2,
And a blocking unit provided under the second adsorption force generating unit to block the generation of the second adsorption force. The method of claim 2,
And the first suction force generated by the first suction force generator is a suction force, and the second suction force generated by the second suction force generator is an electrostatic force or a magnetic force. The method according to claim 1 or 4,
The first adsorption force and the second adsorption force are sequentially generated micro LED transfer head, characterized in that to adsorb the micro LED. The method of claim 5,
The first adsorption force supports the micro LED until the micro LED contacts the bottom surface of the micro LED transfer head, and the second adsorption force causes the micro LED to be in contact with the bottom surface of the micro LED transfer head. Micro LED transfer head characterized in that the adsorption on the lower surface. The method of claim 5,
The second adsorption force supports the micro LED until the micro LED contacts the bottom surface of the micro LED transfer head, and the first adsorption force causes the micro LED to be in contact with the bottom surface of the micro LED transfer head. Micro LED transfer head characterized in that the adsorption on the lower surface. The method according to claim 1 or 4,
The first and second adsorption force is generated at the same time micro LED transfer head, characterized in that for adsorbing the micro LED. As a micro LED transfer head that absorbs micro LED,
A first adsorption force generation unit provided under the micro LED to generate the first adsorption force; And
And a second adsorption force generation unit provided below the first adsorption force generation unit to form part of a lower surface of the micro LED transfer head and generating the second adsorption force.
The micro LED transfer head adsorbs the micro LED through different first and second adsorption forces,
The first suction force generating portion is provided with a hole to generate a suction force which is the first suction force through the hole,
The second adsorption force generating unit is provided with an electrode layer and a dielectric layer to generate an electrostatic force as the second adsorption force through the electrode layer and the dielectric layer, or the second adsorption force generating unit is provided with a magnetic force layer and the second through the magnetic force layer. Micro LED transfer head, characterized in that the magnetic force that is the attraction force is generated. The method of claim 9,
And the electrode layer and the dielectric layer or the magnetic force layer are positioned under the hole where the hole is not formed.

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