KR20200020207A - Transfer head for micro led - Google Patents

Abstract

The present invention relates a micro LED transfer head, which adsorbs a micro LED onto an adsorption surface with vacuum adsorption force, and more specifically, to a micro LED transfer head, which minimizes losses of vacuum pressure with respect to a micro LED, thereby improving an adsorption rate 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 adsorbing the micro LED on the adsorption surface by vacuum suction force.

Currently, the display market is still the mainstream, while OLED is rapidly becoming the mainstream by replacing LCD. With the participation of display makers in the OLED market, micro LEDs (hereinafter referred to as “micro LEDs”) are emerging as another next-generation display. While the key materials of LCD and OLED are liquid crystal and organic materials, respectively, 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 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 is suitable for transfer and display pixel electrodes of micrometer-sized LED chips. There is a need for technology for mounting.

In particular, in connection with a transfer for transferring the micro LED device to the display substrate, as the LED size is reduced to 1 to 100 micrometers (μm) unit, the existing pick & place equipment can not be used, There is a need for a transfer head technology that transfers more precisely. In relation to such a 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 micro LEDs using an electrostatic head (Publication 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 induction of the electrostatic.

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 `` Prior Invention 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 elastic polymer material is also a very important factor.

The Korean Institute of Optical Technology proposed a method of 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 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 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 and thus maintain the basic principles. There are limitations 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 was not considered at all in the prior inventions.

The transfer head for transferring the micro LED to the target substrate may be formed with a hole in which a vacuum pressure is formed in a member of the adsorption surface is configured to adsorb the micro LED of the growth substrate to the adsorption surface. FIG. 1 is a view showing the background of the concept of the present invention, which is a view showing the member 1 adsorbing the micro LED 100 of the transfer head from above. As shown in FIG. 1, the member 1 is formed with a hole 2 in which a vacuum pressure for adsorbing the micro LED 100 is formed. In this case, the hole 2 may be formed to have a circular cross section. However, the hole 2 having a circular cross section may have a vacuum pressure loss area for the micro LED 100 when the micro LED 100 is adsorbed to the hole 2. If a vacuum pressure loss area is present, it may negatively affect the degree of adsorption of the micro LED 100. As a result, there is a problem that the release rate of the micro LED 100 adsorbed to the adsorption surface of the transfer head by the hole 2 can be increased, and the high release rate has a problem of lowering the transfer efficiency of the transfer head.

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 provides a micro LED transfer head which can improve the adsorption degree of the micro LED by forming a vacuum suction hole having a small vacuum pressure loss area for the micro LED by changing the shape of the vacuum suction hole having a circular cross section. The purpose.

The micro LED transfer head according to an aspect of the present invention includes an adsorption member for adsorbing the micro LED with a vacuum suction force, and the suction member has a vacuum suction hole having a square cross section.

In addition, the suction member is characterized in that the communication hole is formed in the upper portion of the vacuum suction hole.

In addition, the adsorption member is characterized in that the anodized film formed by anodizing the metal.

In addition, a barrier layer is provided below the anodization layer.

As described above, the micro LED transfer head according to the present invention can minimize the vacuum pressure loss area for the micro LED when the micro LED is adsorbed due to the shape of the vacuum suction hole in which the vacuum pressure for adsorbing the micro LED is formed. .

In addition, while the vacuum pressure loss area for the micro LEDs is minimized, the adsorption degree for the micro LEDs is increased, thereby increasing the micro LED transfer efficiency.

1 shows a view from above of the background of the concept of the present invention;
2 is a view showing a micro LED to be transferred in the embodiment of the present invention.
3 is a view showing a micro LED structure transferred to a display substrate and mounted in accordance with an embodiment of the present invention.
Figure 4 is a view showing the adsorption member constituting the micro LED transfer head according to a preferred embodiment of the present invention from above.
5 illustrates a micro LED transfer head according to a preferred embodiment of the present invention.
6 is a view showing a state in which a vacuum suction hole having a square cross section of the same horizontal and vertical widths and a hole having a circular cross section are stacked;
FIG. 7 is a diagram illustrating a first modified example of FIG. 5.
8 is a view showing a second modified example of FIG.
9 is a view showing a third modified example of FIG.

The following merely illustrates the principles of the invention. Therefore, those skilled in the art, although not explicitly described or illustrated herein, can embody the principles of the invention and invent various devices included in the concept and scope of the invention. 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 embodiments and states specifically listed. .

The above objects, features, and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby the technical spirit of the invention may be easily implemented by those skilled 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 drawings 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.

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

2 is a diagram illustrating a micro LED 100 to be transferred to the micro LED transfer head 1000 according to an exemplary 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 Ga203.

The micro LED 100 includes 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, and transitions 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). Also, 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 through an etching process, and the plurality of micro LEDs 100 are separated by the laser lift-off process. It is possible to be in a state that can be separated from the (101).

In Figure 2 '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). Although FIG. 2 illustrates that the cross-sectional shape of the micro LED 100 is circular, the present invention is not limited thereto and may have a cross-sectional shape other than a circular cross-section according to a method of manufacturing the growth substrate 101 such as a rectangular cross section. In the following drawings, the cross-sectional shape of the micro LED 100 is shown as a rectangular cross section for convenience.

3 is a view showing a micro LED structure formed by being transferred to a display substrate by a micro LED transfer head 1000 according to an exemplary 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 must 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. It may contain, 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 is 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 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, such as 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, and specifically, the inorganic material may be silicon oxide (SiO 2), silicon nitride (SiN x), silicon oxynitride (SiON), aluminum oxide (Al 2 O 3), titanium oxide (TiO 2), or tantalum. Oxide (Ta 2 O 5), hafnium oxide (HfO 2), zinc oxide (ZrO 2), or 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) or 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, pixel density, and the like of the display device. In one 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 invention 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 a step difference, and the width of the second bank layer 420 may be smaller than the width 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 the wavelength range of 380 nm to 750 nm).

For example, the first bank layer 410 and the second bank layer 420 may include polycarbonate (PC), polyethylene terephthalate (PET), polyethersulfone, 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 The resin may be formed of a thermosetting resin such as a melamine resin or an organic insulating material such as polystyrene, polyacrylonitrile, or 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 such as SiOx, SiNx, SiNxOy, AlOx, TiOx, TaOx, ZnOx, and inorganic nitride. 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 including 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 modification, the first bank layer 410 and the second bank layer 420 may be distributed Bragg reflectors (DBR) having high reflectivity or mirror reflectors formed of 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 wavelengths 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. The micro LEDs 100 are individually or plurally picked up on the growth substrate 101 by the transfer head according to the exemplary embodiment of the present invention, and transferred to the display substrate 301 so that the recesses of the display substrate 301 can be obtained. 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 opposite 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 semi-transparent electrode layer may be formed of indium tin oxide (ITO), indium zinc oxide (IZO; indium zinc oxide), zinc oxide (ZnO; zinc oxide), indium oxide (In2O3; indium oxide), and indium gallium oxide (IGO). at least one selected from the group consisting of indium gallium oxide) and aluminum zinc oxide (AZO).

The passivation layer 520 surrounds the micro LEDs 100 in the recesses. 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.

Hereinafter, the micro LED transfer head 1000 according to an exemplary embodiment of the present invention will be described with reference to FIGS. 4 and 5. 4 is a view showing the adsorption member 10 constituting the micro LED transfer head 1000 according to a preferred embodiment of the present invention, Figure 5 is a micro LED transfer head according to a preferred embodiment of the present invention 1000 shows a diagram.

First, the micro LED transfer head 1000 according to an exemplary embodiment of the present invention will be described with reference to FIG. 5. The micro LED transfer head 1000 of the present invention is configured to include an adsorption member 10 for adsorbing the micro LED 100 with a vacuum suction force and a support member 30 for supporting the adsorption member 10.

The suction member 10 may have a vacuum pressure formed in the vacuum suction hole 10a formed in the suction member 10 to suck the micro LED 100 of the substrate S supported by the substrate support 40. Since the micro LED transfer head 1000 illustrated in FIG. 5 has absorbed the micro LED 100, the substrate S may be a growth substrate 101, a temporary substrate, or a carrier substrate. The display substrate 301 or the target substrate to be transferred may be 100.

The adsorption member 10 may be formed of a material such as metal, nonmetal, ceramic, glass, quartz, silicon (PDMS), resin, or the like, if the horizontal and vertical widths of the vacuum suction hole 10a can be formed to several tens of micrometers or less. Can be. When the material of the adsorption member 10 is a metal material, the micro LED 100 may have an advantage of preventing static electricity during transfer. In the case where the material of the adsorption member 10 is a non-metallic material, the material having no metal properties has an advantage of minimizing the influence of the adsorption member 10 on the micro LED 100 having the properties of metal. When the adsorption member 10 is made of a material such as ceramic, glass, or quartz, it is advantageous to secure rigidity, and the thermal expansion coefficient is low, so that a position error occurs due to thermal deformation of the adsorption member 10 during the transfer of the micro LED 100. This can minimize concerns. If the adsorption member 10 is made of silicon or PDMS material, even if the lower surface of the adsorption member 10 is in direct contact with the upper surface of the micro LED 100, the shock absorbing function may be exerted to prevent damage due to collision with the micro LED 100. It can be minimized. When the material of the adsorption member 10 is a resin material, there is an advantage that the manufacturing of the adsorption member 10 is simple.

The suction member 10 is formed with a vacuum suction hole 10a in which a vacuum pressure for adsorbing the micro LED 100 is formed. The vacuum suction hole 10a has a square cross section. A vacuum suction hole 10a having a square cross section of the suction member 10 will be described in detail with reference to FIG. 4.

As shown in FIG. 4, the suction member 10 has a vacuum suction hole 10a having a square cross section. When the vacuum suction hole 10a is formed in a shape having a rectangular cross section, the vacuum pressure loss area A for the micro LED 100 is minimized when the micro LED 100 is adsorbed to the vacuum suction hole 10a. It becomes possible. In the case of the transfer head of the background art, a hole 2 for adsorbing the micro LED 100 is formed in a shape having a circular cross section in the member 1 for adsorbing the micro LED 100. Referring to FIG. 1, a hole 2 having a circular cross section is formed in the member 1, and the micro LED 100 is adsorbed by the vacuum pressure formed in the hole 2. When the micro LED 100 is adsorbed to the hole 2 having a circular cross section, the adsorption surface of the micro LED 100 may be adsorbed by directly contacting the hole 2 by the circular cross section area of the hole 2. Here, the adsorption surface of the micro LED 100 may mean an upper surface of the micro LED 100 in direct contact with the hole 2. The transfer head on which the hole 2 having a circular cross section is formed may adsorb the micro LED 100 by the vacuum pressure formed in the hole 2 having a circular cross section, but the quadrangle provided in the micro LED transfer head 1000 of the present invention. The vacuum pressure loss area A may exist compared to the vacuum suction hole 10a having a cross section. For example, a hole 2 having a circular cross section provided in the member 1 of the transfer head of FIG. 1 and a square cross section provided in the adsorption member 10 of the micro LED transfer head 1000 of the present invention of FIG. 4. It is assumed that the vacuum suction holes 10a have the same horizontal and vertical widths. Each of the transfer head provided with the hole 2 having a circular cross section and the transfer head provided with the vacuum suction hole 10a having the square cross section of the present invention adsorbs the micro LED 100 having a size of 30 μm × 30 μm. The area where the micro LED 100 is vacuum-adsorbed to the hole 2 having the circular cross section of FIG. 1 is a vacuum pressure relative to the area where the micro LED 100 is vacuum-adsorbed to the vacuum suction hole 10a having the rectangular cross section of FIG. 4. The loss area A will be present. The vacuum pressure loss area A of the hole 2 having a circular cross section compared to the vacuum suction hole 10a having a square cross section will be described in detail with reference to FIG. 6.

FIG. 6 is a view illustrating a vacuum suction hole 10a having a rectangular cross section of the same horizontal and vertical width and a hole 2 having a circular cross section. As shown in Fig. 6, the hole 2 having a circular cross section and the vacuum suction hole 10a having a square cross section are formed in the same horizontal and vertical widths. When the vacuum pressure is formed in the vacuum suction hole 10a and the hole 2, the vacuum pressure loss area A exists in the case of the hole 2 having a circular cross section compared to the vacuum suction hole 10a having a square cross section. Done. The hole 2 having a circular cross section may have a vacuum pressure to adsorb the micro LED 100, but the degree of adsorption of the micro LED 100 may be relatively low due to the vacuum pressure loss area A. However, in the case of the vacuum suction hole 10a having a square cross section formed in the adsorption member 10 of the micro LED transfer head 1000 of the present invention, when the micro LED 100 is adsorbed to the vacuum suction hole 10a, a circular cross section is formed. Since the vacuum pressure loss area A can be minimized compared to the holes 2 having the same, the adsorption degree of the micro LED 100 can be increased. As a result, the separation rate of the micro LED 100 adsorbed to the adsorption surface of the micro LED transfer head 1000 is small, thereby obtaining an effect of increasing the transfer efficiency of the micro LED 100.

As described with reference to FIG. 6, when the vacuum suction hole 10a having the rectangular cross section is formed in the adsorption member 10 with the same horizontal and vertical widths as the hole 2 having the circular cross section, It may be desirable to minimize the vacuum loss area A compared to the hole 2 having a circular cross section and to obtain an effect of improving the adsorption degree of the micro LED 100.

Referring back to FIG. 5, the vacuum suction hole 10a having a square cross section formed in the adsorption member 10 of the micro LED transfer head 1000 of the present invention vertically penetrates the adsorption member 10 vertically. It may be formed in a shape. Since the suction member 10 is fixed to the support member 30 at a spaced distance from the support member 30, when the vacuum pump (not shown) operates, the air inside the vacuum suction hole 10a is smoothly separated by the distance. It is discharged so that a uniform vacuum pressure may be formed in the entire vacuum suction hole (10a).

The vacuum suction hole 10a having a square cross section may be formed in the same direction as the column direction and the row direction pitch of the micro LED 100 on the substrate S, and the column direction of the micro LED 100 on the substrate S. For example, the spacers may be spaced apart at least twice the pitch of the row direction pitch. For example, a vacuum suction hole 10a having a square cross section is formed spaced apart by three times the distance between the column direction and the row direction pitch of the micro LED 100 on the substrate S. In this case, the micro LED transfer head 1000 may include a micro LED of a donor part including a first donor substrate on which a red micro LED is disposed, a second donor substrate on which a green micro LED is disposed, and a third donor substrate on which a blue micro LED is disposed. Three reciprocating movements may be performed between the first to third donor substrates and the target substrate. Through this, the micro LED transfer head 1000 may transfer the red, green, and blue micro LEDs to the target substrate so that the red, green, and blue micro LEDs form a 1 × 3 pixel array. The target substrate may be the display substrate 301 illustrated in FIG. 3, and may be a temporary substrate or a carrier substrate transferred from the growth substrate 101.

The vacuum suction hole 10a having a square cross section includes a micro LED transfer head 1000 according to a preferred embodiment of the present invention to configure the micro LED transfer head 1000 according to the first to third modified examples to be described later. It will be described that the adsorption member 10 is formed at the same pitch interval as the pitch direction of the column direction and the row direction of the micro LED 100 on the substrate (S). However, this is not limited to one embodiment, the pitch interval of the vacuum suction hole (10a) is, as described above, the distance of the pitch in the column direction, row direction of the micro LED 100 on the substrate (S) more than twice the distance. It may be formed spaced apart.

The adsorption member 10 may be an anodization film 11 formed by anodizing a metal in addition to a material such as metal, nonmetal, ceramic, glass, quartz, silicon (PDMS), resin, or the like.

The anodization film 11 refers to a film formed by anodizing a base metal, and the pore refers to a hole formed in the process of forming the anodization film 11 by anodizing the metal. For example, when the base metal is aluminum (Al) or an aluminum alloy, when the base material is anodized, an anodized film 11 made of anodized aluminum (Al ₂ O ₃ ) is formed on the surface of the base material. The anodic oxide film 11 formed as described above is divided into a barrier layer 12 in which pores are not formed therein and a porous layer having pores therein. The barrier layer 12 is positioned above the base material and the porous layer is positioned above the barrier layer. As described above, when the base material is removed from the base material on which the anodization film 11 having the barrier layer and the porous layer is formed on the surface, only the anodization film 11 made of anodized aluminum (Al ₂ O ₃ ) material remains.

The anodic oxide film 11 is uniform in diameter and is formed in a vertical shape to have pores having a regular arrangement. Therefore, when the barrier layer 12 is removed, the pores have a structure vertically penetrated up and down, thereby making it easy to form a vacuum pressure in the vertical direction.

The interior of the anodization film 11 can form an air flow path in a vertical form by vertical pores. The inner width of the pores has a size of several nm to several hundred nm.

The adsorption member 10 may be formed of such an anodization film 11 so that a vacuum suction hole 10a having a square cross section may be formed by etching or the like. The vacuum suction hole 10a having a square cross section may be formed to vertically penetrate the adsorption member 10 vertically as shown in FIG. 5 when the adsorption member 10 is formed of the anodization film 11. It may be formed on the lower portion of the adsorption member 10 as shown in FIG. 7 is a diagram illustrating a first modified example of the micro LED transfer head 1000 according to an exemplary embodiment of the present invention. The micro LED transfer head 1000 according to the first modified example has a rectangular cross section in which the adsorption member 10 constituting the micro LED transfer head 1000 is formed of the anodization film 11 and formed on the adsorption member 10. The vacuum suction hole (10a) is different from the embodiment in that it is formed in the lower portion of the suction member (10).

As shown in FIG. 7, the micro LED transfer head 1000 according to the first modification of the present invention includes an adsorption member 10 and an adsorption member 10 in which a vacuum suction hole 10a having a square cross section is formed. It is configured to include a support member 30 for fixed support.

The adsorption member 10 constituting the micro LED transfer head 1000 according to the first modification may be made of an anodization film 11. The suction member 10 has a vacuum suction hole 10a having a square cross section. The vacuum suction hole 10a having a square cross section formed in the suction member 10 may be formed in the lower portion of the suction member 10.

Since the adsorption member 10 constituting the micro LED transfer head 1000 of the first modified example is made of the anodization film 11, there are naturally occurring pores of the anodic oxidation film 11. The vacuum suction hole 10a may be formed at a lower portion of the adsorption member 10 formed of the anodization film 11, and specifically, may be formed to have a width greater than that of pores in the lower surface of the anodization film 11. The vacuum suction hole 10a having a square cross section may be formed on the bottom surface of the anodic oxide film 11 to be in communication with the pores. Since the anodic oxide film 11 is formed of pores having vertically penetrated vertically, the vacuum suction hole 10a having a rectangular cross section formed on the lower surface of the anodic oxide film 11 is formed on the lower surface of the pores to communicate with the pores. It may be in the form of. Therefore, when the vacuum pump is operated, a vacuum is applied to the vacuum suction hole 10a through the pores, and a vacuum pressure is formed in the vacuum suction hole 10a. In the case of pores, since the vacuum suction hole 10a formed in the lower portion of the pores has a square cross section, the vacuum suction hole 10a minimizes the vacuum pressure loss area A so that the micro LED 100 Can be adsorbed effectively.

8 illustrates a second modified example of the micro LED transfer head 1000 according to the exemplary embodiment of FIG. 5. In the micro LED transfer head 1000 of the second modified example illustrated in FIG. 8, the suction member 10 is an anodized film 11 and the vacuum suction hole 10a having a square cross section formed in the suction member 10 is an absorption member. There is a difference from the embodiment in that the communication hole 20 is formed in the lower portion of the (10) and the upper portion of the vacuum suction hole (10a).

As shown in FIG. 8, in the micro LED transfer head 1000 according to the second modified example, a vacuum suction hole 10a is formed below the suction member 10, and a communication hole is disposed above the vacuum suction hole 10a. 20 is formed. Since the adsorption member 10 constituting the micro LED transfer head 1000 of the second modified example is the anodization film 11, a communication hole (not shown) is formed on the upper portion of the vacuum suction hole 10a and the vacuum suction hole 10a by etching or the like. 20) can be formed. The communication hole 20 may be formed in a shape having a square cross section, such as a vacuum suction hole 10a having a square cross section. The rectangular cross section of the communication hole 20 may be formed with a width of the horizontal and vertical smaller than the width and the vertical width of the rectangular cross section of the vacuum suction hole (10a).

The suction member 10 has a vacuum suction hole 10a formed at a lower portion thereof, and a communication hole 20 is formed at an upper portion of the vacuum suction hole 10a. The rectangular cross section of the communication hole 20 is a vacuum suction hole 10a. It is formed with a width smaller than the rectangular cross-section of the vacuum suction hole (10a) and the communication hole 20 may be formed in the form of multiple stages. In addition, the suction member 10 has a vacuum suction hole 10a having a square cross section at the bottom thereof, and a communication hole 20 having a square cross section at the upper portion of the vacuum suction hole 10a is formed to have a horizontal and vertical width. The other vacuum suction hole 10a and the communication hole 20 may be shaped to penetrate the adsorption member 10 up and down.

The communication hole 20 is formed in a rectangular cross section having a horizontal width and a vertical width smaller than the rectangular cross section of the vacuum suction hole 10a, so that the air discharge area is relatively small. As a result, when the vacuum pump operates, the formation time of the vacuum pressure formed while the air inside the vacuum suction hole 10a and the communication hole 20 is discharged to the outside may be shortened compared to the embodiment. The micro LED transfer head 1000 according to the second modified example has a horizontal cross section and a vertical cross section of a rectangular cross section of the communication hole 20 formed in the upper portion of the vacuum suction hole 10a. And by forming smaller than the vertical width it is possible to shorten the vacuum pressure forming time to obtain the effect of improving the transfer efficiency of the micro LED (100).

9 illustrates a third modified example of the micro LED transfer head 1000 according to the preferred embodiment of the present invention. In the micro LED transfer head 1000 according to the third modified example, a shielding part is formed on at least a part of the surface of the anodization film 11, which is the adsorption member 10, so that the adsorption member 10 vacuum-adsorbs the micro LED 100. There is a difference from the embodiment in that it comprises a region and a non-adsorption region that does not adsorb the micro LED (100).

The suction member 10 includes a vacuum suction hole 10a having a rectangular cross section, and includes a suction area for adsorbing the micro LED 100 and a non-adsorption area for preventing the micro LED 100 from being formed by a shield.

Preferably, the adsorption region in which the vacuum suction hole 10a having the rectangular cross section is formed is a region through which the upper and lower pores pass, and the non-adsorption region is a region in which at least one portion of the upper and lower pores is closed. Can be. Since a vacuum suction hole 10a having a rectangular cross section is formed in the suction region, the suction region may be a region through which the vacuum suction hole 10a having a rectangular cross section passes through the upper and lower sides of the suction member 10.

As illustrated in FIG. 9, the non-adsorption region may be implemented by forming a shield on at least part of the surface of the anodization film 11. A shield is formed on at least a part of the surface of the anodization film 11 that is the adsorption member 10. The shielding portion is formed to block inlets of pores exposed to at least part of the surface of the anodization film 11. The shield may be formed on at least some of the upper and lower surfaces of the anodization film 11. 9, the shielding portion is formed on at least a part of the lower surface of the adsorption member 10 in the adsorption member 10 of the micro LED transfer head 1000 according to the third modified example of FIG. 9. The shielding portion is not limited in material and shape thickness as long as it can perform a function of blocking the entrance of pores exposed to the surface of the anodization film 11. Preferably, the shield may be further formed of a photoresist (including PR, dry film PR) or a metal material, and may be the barrier layer 12.

The adsorption member 10 constituting the micro LED transfer head 1000 according to the third modified example is an anodization film 11 and at least a part of the lower surface of the anodization film 11 is provided with a barrier layer 12 as a shield. .

The non-adsorption region may be formed by closing one of the upper and lower portions of the vertical pores by the barrier layer 12 formed during the production of the anodization film 11, and the adsorption region may be formed by etching, for example. The layer 12 may be removed so that the upper and lower portions of the vertical pores penetrate each other. Since a vacuum suction hole 10a having a rectangular cross section is formed in the adsorption region, the adsorption region may be formed such that pores are removed by etching or the like so that the vacuum suction hole 10a having a rectangular cross section penetrates up and down.

In the micro LED transfer head 1000 of the third modified example of FIG. 9, a vacuum suction hole 10a having a square cross section formed in the adsorption member 10 is formed to penetrate the adsorption member 10 up and down. This is not limited. The vacuum suction hole 10a having a square cross section formed in the adsorption member 10 constituting the micro LED transfer head 1000 of the third modified example is the micro LED transfer head according to the first and second modified examples described above. Like the vacuum suction hole 10a having a square cross section formed in the adsorption member 10 constituting the 1000, the lower portion of the adsorption member 10 is in communication with the pores of the adsorption member 10, which is the anodization film 11; It may be formed only or may be provided with a communication hole 20 having a width different from the horizontal and vertical width of the rectangular cross-section of the vacuum suction hole (10a).

In FIG. 9, the barrier layer 12 is positioned below the anodization layer 11, but the anodization layer 11 illustrated in FIG. 9 is positioned such that the barrier layer 12 is positioned above the anodization layer 11. Upside down can be inverted to form a non-adsorption area.

On the other hand, the non-adsorption area was described as one of the top and the load of the pores closed by the barrier layer 12, the other side is not closed by the barrier layer 12 is added to the coating layer is added, May be configured to be all closed. In the non-adsorption area, the upper and lower surfaces of the anodic oxide film 11 are both closed, so that foreign matter may remain in the pores of the non-adsorption area, compared to the configuration in which at least one of the upper and lower surfaces of the anodization film 11 is closed. This may be advantageous in that the concern can be reduced.

In the micro LED transfer head 1000 according to the third modified example, a vacuum suction hole 10a having a rectangular cross section is formed in the adsorption area, thereby minimizing the vacuum pressure loss area A so as to adsorb the micro LED 100. . As a result, it is possible to perform a transfer process having a high adsorption degree of the micro LED 100 and to implement a micro LED transfer head 1000 having high transfer efficiency. In addition, the risk of foreign matter remaining in the pores through the barrier layer 12 of the non-adsorption area is reduced, and when the air inside the vacuum suction hole 10a is discharged to the outside to form a vacuum pressure, there is a problem of preventing the vacuum pressure formation due to the foreign matter. It can be minimized.

As described above, although described with reference to a preferred embodiment 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.

1: absence 2: hole
10: adsorption member 10a: vacuum suction hole
11: anodized film 12: barrier layer
20: communication hole 30: support member
40: substrate support
100: micro LED
S: Substrate A: Vacuum Loss Area

Claims (4)

Adsorption member for adsorbing micro LED by vacuum suction force,
Micro LED transfer head, characterized in that the suction member is formed with a vacuum suction hole having a rectangular cross section.
The method of claim 1,
The suction member is a micro LED transfer head, characterized in that the communication hole is formed in the upper portion of the vacuum suction hole.
The method of claim 1,
The adsorption member is a micro LED transfer head, characterized in that the anodic oxidation film formed by anodizing a metal.
The method of claim 3,
Micro LED transfer head, characterized in that the barrier layer is provided below the anodization film.

Images