WO2012148231A2

WO2012148231A2 - Micro led bundle and method for manufacturing same

Info

Publication number: WO2012148231A2
Application number: PCT/KR2012/003319
Authority: WO
Inventors: 도영락; 성연국
Original assignee: 국민대학교 산학협력단; 피에스아이 주식회사
Priority date: 2011-04-28
Filing date: 2012-04-27
Publication date: 2012-11-01
Also published as: KR20120122160A; KR101209446B1; WO2012148231A3

Abstract

The present invention relates to a micro LED bundle and to a method for manufacturing same, and more specifically, to a micro LED bundle, comprising: a first conductive semiconductor layer; an active layer which is formed on the first conductive semiconductor layer; and a plurality of micro LEDs having a diameter which is micro- or nano-sized and including a second conductive layer that is formed on the active layer, wherein the plurality of micro LEDs are provided with a binder on the outer circumferential surfaces thereof to form one bundle, and to a method for manufacturing the micro LED comprising the following steps: 1) sequentially forming the first conductive semiconductor layer, the active layer, and the second conductive semiconductor layer, on a substrate; 2) forming the plurality of micro LEDs by etching the LEDs comprising the first conductive semiconductor layer, the active layer, and the second conductive semiconductor layer so that the diameters of the LEDs are in the nano or micro size range; and 3) forming a plurality of bundles by forming the binder on the outer circumferential surfaces of the plurality of LEDs. According to the present invention, the nano- or micro-sized micro LED can be effectively produced by combining a top-down method and a bottom-up method, and the light emitting efficiency can be improved by preventing surface defects on the micro LEDs that are produced.

Description

Micro LED Bundle and Manufacturing Method

The present invention relates to an ultra-small LED device bundle and a method of manufacturing the same, and more particularly to an ultra-small LED device bundle and a method for manufacturing the ultra-small LED device that can minimize the defect rate when attached to the display substrate. It is about.

Currently, efforts are being made to develop a light emitting diode (LED) having high light conversion efficiency by improving a nitride semiconductor growth structure or a manufacturing process of a grown thin film using a nitride semiconductor having a large band gap. .

By the way, known to date LED TV is LCD as a LCD TV employing a cold cathode fluorescent lamp (cold cathode fluorescent lamp, CCFL) white or tri-color LED devices on behalf of the backlight in the backlight used in conventional LCD TV, precisely with the LED back light TV. Specifically, the current commercially available full-color LED display is the only product that can be encountered in everyday life, the display for outdoor billboards in which tens of thousands to hundreds of thousands of red, green and blue three-color LED lamps are inserted into a very large substrate. Thus, until now, a full-featured LED full-color display has not been realized as a home TV or computer monitor.

The reason why the existing LED device cannot be developed into a TV or monitor size display is due to the fundamental limitation of the technical method of manufacturing the display using the LED device and the method of implementing full color. Conventional LED device manufacturing method is a metal organic chemical vapor deposition (MOCVD) method on the sapphire substrate of 2 ~ 8 inches size p-semiconductor layer, quantum well layer, n-semiconductor layer of III-V material After depositing these, it is a method of manufacturing the LED device of the required form through various post-processing such as cutting / wiring / packaging. If you build your own display for a TV using this method, you can simply calculate the 40-inch TV only by connecting 5 to 40 sheets of 2 to 8 inch wafers. Therefore, there are a number of problems scattered in the current technology to realize a TV-class display directly using LED devices using current manufacturing technology. In addition, in order to realize full color, red, green, and blue primary LED devices must be embedded together in one pixel, so it is impossible to realize LED full color display by simply connecting red, green, and blue LED wafers together. .

To realize high-efficiency LED displays, there is a bottom-up method of directly growing III-V thin film and nanorod LED devices at patterned pixel positions of large-area glass substrates for actual displays. It is known that the process of directly depositing on a large substrate such as a display size for TV is impossible in the MOCVD method of growing III-V thin film. Not only that, it is also known to grow a high crystalline / high efficiency group III-V thin film and nanorod heterojunction LED device on a transparent electrode patterned on a transparent amorphous glass substrate. Due to these technical limitations, except for small devices, a method of realizing a TV or monitor-class full-color display by directly growing LED devices on a large-area glass substrate has not been attempted.

Another approach being pushed by many researchers to realize LED displays is a bottom-up approach based on nanotechnology. This method is a method of realizing a large-area display by growing a nanorod type LED on a single crystal substrate, and then removing a portion and rearranging it in a bottom-up manner on an electrode patterned with pixels. However, since the nanorod LED manufactured by the bottom-up method has poor luminous efficiency compared to the thin film LEDs grown on the wafer, even if the LED display is implemented with this technology, there is a problem of efficiency degradation for a considerable period of time. Can't solve it. In addition, in order to arrange the nanorod LED device grown in the bottom-up method on the electrode by the bottom-up self-assembly, it is essential to obtain a nanorod device having a uniform size and height. However, using nanorod growth methods such as the well-known Vapor-Liquid-Solid (VLS) method, it is possible to mass-produce nanorod LED devices with uniform size and characteristics that are easy to self-assemble. This is very small.

Another method is a top-down method that cuts high-efficiency LED devices to create an LED display. In general, this method is a method of implementing a display in a one-to-one correspondence method in which micro-LED devices manufactured in a top-down manner are arranged one by one in a sub-pixel position of a large area glass substrate. Specifically, in the case of the micro-sized LED display, the individual micro LEDs manufactured by the top-down method are manufactured for each sub-pixel, and thus, were developed for the small micro LED display. In this case, the LED device is grown on a sapphire substrate, and then patterned to a micro size to manufacture a micro LED device, and then the electrodes are wired to implement a micro LED display smaller than the wafer substrate size. If this method is used, there is no problem in efficiency, but it is impossible to realize a large-area LED display due to limitations in substrate size and manufacturing process.

As a result, the ultra-small LED device manufactured by the conventional top-down or bottom-up method is very likely to cause problems of efficiency and stability due to an increase in surface defects caused by etching. In addition, in the case of an independent micro LED device, due to the surface polarity between the micro devices, mutual cohesion occurs and aggregates are formed, which may result in a large number of defects in the pixel patterning process. Therefore, there is a limitation in implementing mass-efficient high efficiency / large-area LED display devices only by manufacturing independent micromini LED devices.

Furthermore, when the ultra-small LED device manufactured by the conventional method is placed in a subpixel (pixel position) of the LED display substrate, the micro LED device is too small to stand on the subpixel of the LED display because the size of the LED device is too small. There was a problem of lying down or upside down.

The present invention has been made to solve the above-mentioned problems, the first technical problem of the present invention, the surface defects caused by the etching operation of the small LED device can be solved the problem of efficiency and stability and the cohesion between the small LED device due to the increase in surface defects It is to provide a method of manufacturing a small LED device bundle.

A second technical problem of the present invention is to provide a micro LED bundle that enables the micro LED device to be accurately positioned without lying on its side or flipped over on a subpixel (pixel position) of the LED display.

The present invention to solve the first technical problem,

1) sequentially forming a first conductive semiconductor layer, an active layer and a second conductive semiconductor layer on the substrate; 2) forming a plurality of ultra-small LED devices by etching the diameter of the LED device including the first conductive semiconductor layer, the active layer, and the second conductive semiconductor layer to have a nano or micro size; And 3) forming a plurality of bundles by forming a binder on the outer circumferential surface of the plurality of micro LEDs, thereby providing a method of manufacturing a micro LED bundle.

According to an embodiment of the present invention, the first conductive semiconductor layer may include at least one n-type semiconductor layer, and the second conductive semiconductor layer may include at least one p-type semiconductor layer.

According to another embodiment of the invention, the step 2) is;

2-1) sequentially forming a second electrode layer, an insulating layer, and a metal mask layer on the second conductive semiconductor layer; 2-2) forming a polymer layer on the metal mask layer and forming a pattern on the polymer layer at nano or micro intervals; 2-3) dry or wet etching the first conductive semiconductor layer, the active layer and the second conductive semiconductor layer at nano or micro intervals according to a pattern; And 2-4) removing the insulating layer, the metal mask layer, and the polymer layer.

According to another embodiment of the present invention, the step 2);

2-5) forming a second electrode layer, an insulating layer, and a metal mask layer on the second conductive semiconductor layer; 2-6) forming a nanosphere or microsphere monolayer on the metal mask layer and performing self-assembly; 2-7) dry or wet etching the first conductive semiconductor layer, the active layer and the second conductive semiconductor layer at nano or micro intervals according to a pattern; And 2-8) removing the insulating layer, the metal mask layer, and the single layer film.

According to another embodiment of the present invention, the nanospheres or microspheres may be a polystyrene material.

According to another embodiment of the present invention, step 3) is performed; 3-1) forming a supporting film on the second electrode layer; 3-2) forming an insulating film on an outer circumferential surface including the first conductive semiconductor layer, the active layer and the second conductive semiconductor layer; 3-3) removing the substrate; 3-4) forming a plurality of bundles by forming a binder on an outer circumferential surface of the plurality of ultra-small LED elements having an insulating film formed thereon; 3-5) forming a first electrode under the first conductive semiconductor layer; 3-6) attaching a coupling linker for self-assembly to the first electrode formed under the first conductive semiconductor layer; And 3-7) manufacturing the plurality of micro LED bundles by removing the support film.

According to another embodiment of the present invention, the binder is hydrophobic, and one of the plurality of bundles may include 5 to 100 micro LEDs.

In addition, the present invention to solve the second problem,

A first conductive semiconductor layer; An active layer formed on the first conductive semiconductor layer; A plurality of micro LED devices having a diameter of a micro or nano size including a second conductive semiconductor layer formed on the active layer, the plurality of micro LED devices is a binder formed on the outer peripheral surface to form a bundle Provides a compact LED device bundle.

According to an embodiment of the present invention, the binder is hydrophobic, and one bundle may include 5 to 100 micro LEDs.

According to another embodiment of the present invention, a first electrode layer may be formed below the first conductive semiconductor layer, and a second electrode layer may be formed above the second conductive semiconductor layer.

According to another embodiment of the present invention, the micro LED device may include an insulating film formed inside the binder.

According to another embodiment of the present invention, a coupling linker may be included on the surface of at least one electrode layer of the lower surface of the first electrode layer and the upper surface of the second electrode layer.

According to another embodiment of the present invention, the coupling linker may be complementarily coupled to the substrate of the LED display.

According to another embodiment of the present invention, the first conductive semiconductor layer may include at least one n-type semiconductor layer, and the second conductive semiconductor layer may include at least one p-type semiconductor layer.

According to another embodiment of the present invention, the binder may include one or more materials selected from the group consisting of a photosensitive polymer and spin-on-glass.

Hereinafter, in the present invention, each layer (film), region, pattern or structures is described as being formed on or "under" a substrate, each layer (film), region, or pattern. In this case, the terms "on" and "under" include both "directly" and "indirectly". In addition, the reference | standard about the top or bottom of each layer is demonstrated based on drawing.

The manufacturing method of the ultra-small LED device according to the present invention can solve the problem of cohesion between the ultra-small LED device, the surface defects increase due to the etching operation, thereby reducing efficiency and stability and the ultra-small LED device.

Further, according to the present invention, it is not only easy to handle very small LED elements, but also it is possible to accurately position the LED elements on a subpixel (pixel position) of the LED display without lying on its side or upside down. This can dramatically improve the efficiency of the LED display.

1 is a cross-sectional view showing a step of forming an LED basic device layer according to an embodiment of the present invention.

2 is a cross-sectional view illustrating a step of forming a second electrode layer, an insulating layer, and a metal mask layer on a second conductive semiconductor layer of the present invention.

3 is a cross-sectional view showing a step of forming a nanosphere or microsphere monolayer film on the metal mask layer of the present invention.

4 is a cross-sectional view showing the ashing step of the nanospheres or microspheres monolayer film of the present invention.

5 is a cross-sectional view showing an etching step of the present invention.

6 is a cross-sectional view showing a step of removing a spear monolayer film, a metal mask layer, and an insulating layer of the present invention.

7 is a cross-sectional view showing a step of attaching a support film on the second electrode layer of the present invention.

8 is a view showing a step of coating an insulating film on the outer circumferential surface of each LED device of the present invention.

9 is a cross-sectional view showing a step of coating the insulating film formed on the outer peripheral surface of the LED device of the present invention with a hydrophobic film.

FIG. 10 is a view illustrating a step of manufacturing a micro LED device bundle by commonly connecting a polymer binder to an insulating film formed on outer surfaces of the LED devices of the present invention.

11 is a cross-sectional view illustrating depositing an electrode under a first conductive semiconductor layer from which a substrate of the present invention is removed.

12 is a cross-sectional view showing a step of coating a coupling linker for self-assembly on the surface of the electrode of the present invention.

13 is a cross-sectional view showing a step of manufacturing the independent ultra-small LED device by removing the support film of the present invention.

FIG. 14 is a perspective view illustrating an ultra-small LED device bundle manufactured by commonly connecting a binder to the outer circumferential surfaces of the LED devices of the present invention.

FIG. 15 is a perspective view illustrating an ultra-small LED device bundle manufactured by forming an insulating film on an outer circumferential surface of each LED device of the present invention and connecting the same with a binder.

FIG. 16 is a perspective view of a micro LED device in which a coupling linker for self-assembly is formed on a surface of an electrode of the present invention. FIG.

FIG. 17 is an ink or paste containing the ultra-small LED device bundle of the present invention.

18 is an electron microscope photograph of the cross-section of the LED basic device layer of the present invention.

19 is an electron microscope photograph of a cross section in which an insulating layer and a metal mask layer are formed on a second conductive semiconductor layer of the present invention.

20A is an electron microscope photograph of a cross section of a nanosphere monolayer film formed on a metal mask layer of the present invention, and FIG. 20B is an electron microscope photograph of a plane thereof.

Fig. 21A is an electron microscope photograph of a cross section obtained by ashing the nanosphere monolayer film of the present invention under an O ₂ gas atmosphere, and Fig. 21B is an electron microscope photograph of the plane thereof.

FIG. 22A is an electron microscope photograph of a cross-section of a metal mask layer etched in a Cl ₂ gas atmosphere using a nanosphere of which the size of the present invention is reduced, and FIG. 22B is an electron microscope photograph of the plane thereof.

FIG. 23A is an electron microscope photograph of a cross section of a metal mask layer pattern transferred as it is in the shape of polystyrene by an etching process of the present invention, and FIG. 23B is an electron microscope photograph of a plane thereof.

24A is an electron microscope photograph of a cross section obtained by etching SiO ₂ (insulating layer) under CF ₄ and O ₂ gas atmospheres using the metal mask layer pattern of the present invention, and FIG. 24B is an electron microscope photograph of the plane thereof. to be.

FIG. 25A is an electron microscope photograph of a section etched by the ICP method under an SiCl ₄ and Ar gas atmosphere using the etched insulating layer of the present invention, and FIG. 25B is an electron microscope photograph of the plane.

FIG. 26A is an electron micrograph of a cross-sectional view after removing an insulating layer used as a mask of the present invention, and FIG. 26B is an electron micrograph of a plane thereof.

27A and 27B show contact angles before (27a) and after (27b) of coating the hydrophobic coating (octadecyltrichlorosilane) on the semiconductor layer coated with the insulating coating (Al ₂ O ₃ ) of the present invention. ) Is a drawing measured.

28A and 28B are electron micrographs of cross-sections of laser-lift-off processes using a buffer layer or an undoped semiconductor layer and a sapphire substrate to which the supporting film of the present invention is not attached.

29A and 29B are electron micrographs of a cross section obtained by etching the buffer layer or the undoped semiconductor layer to some extent in order to expose the first conductive semiconductor layer of the present invention.

30a and 30b are electron micrographs observed in cross section after further etching by the ICP method of the present invention.

FIG. 31A is an electron microscope photograph of a cross section etched to expose a first conductive semiconductor layer by the ICP method of the present invention, and FIG. 31B is an electron microscope photograph of a plane thereof.

32 is a photograph observing a cross-section of a micro LED device manufactured by coating a binder of the present invention in a bundle form with an electron microscope.

FIG. 33 is a photograph of an electron microscope of a cross section of the electrode Ti deposited on the first conductive semiconductor layer by a sputtering method after the binder of the present invention is slightly removed through an ashing process.

34A and 34B are photographs observed by electron microscopy of a bundle-type micro LED having the support film of the present invention removed with acetone.

35 is a photograph of observing the bundle-type microminiature LED device of the present invention on an electrode substrate with an electron microscope.

36 is a diagram illustrating a spectrum measured after aligning the bundled microminiature LED elements of the present invention to an electrode substrate.

37A to 37C are photographs visually observing a state in which the ultra-small LED bundle of the present invention emits blue light.

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

As described above, when the ultra-small LED device manufactured according to the prior art is placed on the subpixel (pixel position) of the LED display substrate, the size of the LED device is too small, so the ultra-small LED device on the subpixel of the LED display There was a problem in that it could not be placed right sideways, lying sideways or upside down.

In the present invention, 1) forming a first conductive semiconductor layer, an active layer and a second conductive semiconductor layer sequentially on the substrate; 2) forming a plurality of ultra-small LED devices by etching the diameter of the LED device including the first conductive semiconductor layer, the active layer, and the second conductive semiconductor layer to have a nano or micro size; And 3) forming a binder on an outer circumferential surface of the plurality of micro LEDs, thereby providing a method of manufacturing a micro LED bundle including a step of forming a plurality of bundles.

First, as step 1), a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer are sequentially formed on a substrate. Specifically, Figure 1 is a cross-sectional view showing the step of forming the LED elementary device layer according to an embodiment of the present invention, the first conductive semiconductor layer 11, the active layer 12 and the second conductive semiconductor on the substrate 10 Forming a layer (13).

The substrate 10 may be a transparent substrate such as sapphire substrate (Al ₂ O ₃ ) and glass. In addition, the substrate 10 may be selected from the group consisting of GaN, SiC, ZnO, Si, GaP and GaAs, conductive substrates. Hereinafter, the embodiment will be described as an example of the sapphire substrate. An uneven pattern may be formed on the upper surface of the substrate 10.

The nitride semiconductor is grown on the substrate 10, and the growth equipment includes electron beam deposition, physical vapor deposition (PVD), chemical vapor deposition (CVD), and plasma laser deposition (PLD). ), Dual-type thermal evaporator, sputtering, metal organic chemical vapor deposition (MOCVD), etc., but is not limited thereto.

A buffer layer and / or an undoped semiconductor layer (not shown) may be formed on the substrate 10. The buffer layer may be formed of at least one of GaN, InN, AlN, InGaN, AlGaN, InAlGaN, and AlInN as a layer for reducing a difference in lattice constant from the substrate 10. The undoped semiconductor layer may be implemented as an undoped GaN layer, and functions as a substrate on which a nitride semiconductor is grown. The buffer layer and the undoped semiconductor layer may be formed of only one layer, or both layers may or may not be formed.

According to a preferred embodiment of the present invention, the thickness of the substrate may be 400 to 1500 μm, but is not limited thereto.

The first conductive semiconductor layer 11 is formed on the substrate 10. The first conductive semiconductor layer 11 may include, for example, an n-type semiconductor layer, and the n-type semiconductor layer may include InxAlyGa1-x-yN (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x At least one of a semiconductor material having a compositional formula of + y ≦ 1), for example, InAlGaN, GaN, AlGaN, InGaN, AlN, InN, or the like, may be selected, and the first conductive dopant (eg, Si, Ge, Sn, etc.) may be doped. Can be. According to a preferred embodiment of the present invention, the thickness of the first conductive semiconductor layer may be 1.5 to 5㎛, but is not limited thereto.

The active layer 12 is formed on the first conductive semiconductor layer 11 and may be formed in a single or multiple quantum well structure. A cladding layer (not shown) doped with a conductive dopant may be formed on and / or under the active layer 12, and the cladding layer doped with the conductive dopant may be implemented as an AlGaN layer or an InAlGaN layer. In addition, materials such as AlGaN and AlInGaN may also be used as the active layer 12. In the active layer 12, when an electric field is applied, light is generated by the combination of the electron-hole pairs. According to a preferred embodiment of the present invention, the thickness of the active layer may be 0.05 to 0.25 μm, but is not limited thereto.

A second conductive semiconductor layer 13 is formed on the active layer 12, and the second conductive semiconductor layer 13 may be implemented with at least one p-type semiconductor layer, wherein the p-type semiconductor layer is InxAlyGa1-x. Any one or more of semiconductor materials having a compositional formula of -yN (0≤x≤1, 0≤y≤1, 0≤x + y≤1), such as InAlGaN, GaN, AlGaN, InGaN, AlN, InN, etc., may be selected. The second conductive dopant (eg, Mg) may be doped. The light emitting structure includes the first conductive semiconductor layer 11, the active layer 12, and the second conductive semiconductor layer 13 as minimum components, and different phosphor layers and active layers above and below each layer. , May further include a semiconductor layer and / or an electrode layer. According to a preferred embodiment of the present invention, the thickness of the second conductive semiconductor layer may be 0.08 to 0.25 μm, but is not limited thereto.

Next, step 2) includes the first conductive semiconductor layer, the active layer, and the second conductive semiconductor layer to manufacture a plurality of micro LED devices by etching the diameter of the LED device to have a nano or micro size.

To this end, according to a preferred embodiment of the present invention, 2-5) forming a second electrode layer, an insulating layer and a metal mask layer on the second conductive semiconductor layer; 2-6) forming a nanosphere or microsphere monolayer on the metal mask layer and performing self-assembly; 2-7) dry or wet etching the first conductive semiconductor layer, the active layer and the second conductive semiconductor layer at nano or micro intervals according to a pattern; And 2-8) removing the insulating layer, the metal mask layer, and the single layer film.

2 is a cross-sectional view illustrating a step of forming the second electrode layer 20, the insulating layer 21, and the metal mask layer 22 on the second conductive semiconductor 13 layer of the present invention. First, the second electrode layer 20 may use a metal or a metal oxide used in a conventional LED device, preferably Cr, Ti, Al, Au, Ni, ITO and oxides or alloys thereof, alone or mixed. It can be used, but is not limited thereto. According to a preferred embodiment of the present invention, the thickness of the metal mask layer may be 0.02 ~ 0.1㎛, but is not limited thereto.

The insulating layer 21 formed on the second electrode layer 20 may serve as a mask for continuous etching of the second electrode layer, the second conductive semiconductor layer, the active layer, and the first conductive semiconductor layer. Nitride may be used, and as a representative example, silicon oxide (SiO ₂ ) or silicon nitride (SiN) may be used, but is not limited thereto.

According to a preferred embodiment of the present invention, the thickness of the insulating layer may be 0.5 to 1.5㎛, but is not limited thereto.

The metal mask layer 22 formed on the insulating layer 21 serves as a mask layer for etching, and may be a metal commonly used. For example, chromium (Cr) metal may be used. May be, but is not limited thereto. According to a preferred embodiment of the present invention, the thickness of the metal mask layer may be 30 ~ 150 nm, but is not limited thereto.

3 is a cross-sectional view showing a step of forming a nanosphere or microsphere monolayer film 30 on the metal mask layer 22 of the present invention. Specifically, the nanospheres or microspheres monolayer film is formed to serve as a mask for etching the metal mask layer 22, and the method of forming the sphere particles may use the self-assembly of the spheres. In order to form a complete structure arrangement by self-assembly of spears, the spears are sent on the surface of the water at a constant speed to self-assemble each other. Since the spheres formed while spreading in water are small and irregular, they are added regularly with additional energy and surfactants to form a large, regular array of spheres, and the regular spheres on the metal layer by floating one layer of spheres over the metal mask layer 22. The spear monolayer film can be formed. The diameter of the sphere particles can be selectively used according to the desired diameter of the ultra-small LED device to be produced, preferably polystyrene spheres, silica spheres and the like having a diameter of 50 ~ 3000nm, but is not limited thereto.

4 is a cross-sectional view showing the ashing step of the nanospheres or microspheres monolayer film 30 of the present invention, the spacing of the sphere particles are spaced apart. It can be achieved through an ashing process of a conventional spear monolayer film, and preferably, an ashing process (eg, heating) is performed through oxygen (O ₂ ) -based reactive ion ashing and plasma ashing. Can be performed.

FIG. 5 is a cross-sectional view illustrating an etching step of the present invention. Specifically, FIG. 4 illustrates a process of forming holes by etching between spear particles spaced through an ashing process. In this case, the portion in which the sphere particles 30 are formed is not etched, and the spaced part spaced between the sphere particles and the sphere particles is etched to form holes. The hole may be selectively formed from the metal mask layer 22 to the substrate 10. The etching process may use a dry etching method such as reactive ion etching (RIE) or inductively coupled plasma reactive ion etching (ICP-RIE).

Unlike the wet etching method, the dry etching method is capable of unidirectional etching and is suitable for forming such a pattern. That is, the wet etching method is an isotropic etching, the etching is performed in all directions, but the dry etching method can be etched mainly in the depth direction to form a hole, the size and spacing of the holes, etc. It can be formed in a desired pattern.

In this case, when the RIE or ICP-RIE method is used, Cl ₂ , O _2, or the like may be used as an etching gas capable of etching the metal mask.

The spacing (A) of the LED device manufactured by the etching process is matched with the diameter of the sphere particles 30, in this case, the spacing (A) of the LED device may be in the nanometer unit or micrometer unit, more preferably Preferably from 50 to 3000 nm.

6 is a step of removing the sphere particles 30, the metal mask layer 22 and the insulating layer 21 after the etching process, the removal process may be performed by a conventional wet etching or dry etching method. .

According to another embodiment of the invention, the step 2) is; 2-1) sequentially forming a second electrode layer, an insulating layer, and a metal mask layer on the second conductive semiconductor layer; 2-2) forming a polymer layer on the metal mask layer and forming a pattern on the polymer layer at nano or micro intervals; 2-3) dry or wet etching the first conductive semiconductor layer, the active layer and the second conductive semiconductor layer at nano or micro intervals according to a pattern; And 2-4) removing the insulating layer, the metal mask layer, and the polymer layer.

Specifically, after forming the second electrode layer, the metal mask layer and the insulating layer on the second conductive semiconductor layer, a conventional polymer layer that can be used for conventional lithography, etc. is formed on the metal mask layer, and a photo on the polymer layer Achieved by forming patterns at nano or micro intervals through methods such as lithography, e-beam lithography, or nano imprint lithography, followed by dry or wet etching and removal of insulating layers, metal mask layers, and polymer layers Can be.

Next, as a step 3), one bundle may be formed by forming a binder on the outer circumferential surface of the plurality of ultra-small LED devices to manufacture the micro-LED bundle according to the present invention.

Step 3); 3-1) forming a supporting film on the second electrode layer; 3-2) forming an insulating film on an outer circumferential surface including the first conductive semiconductor layer, the active layer and the second conductive semiconductor layer; 3-3) removing the substrate; 3-4) forming a plurality of bundles by forming a binder on an outer circumferential surface of the plurality of micro LED devices having an insulating film formed thereon; 3-5) forming a first electrode under the first conductive semiconductor layer; 3-6) attaching a coupling linker for self-assembly to the first electrode formed under the first conductive semiconductor layer; And 3-7) manufacturing the plurality of micro LED bundles by removing the support film.

7 is a cross-sectional view showing the step of attaching the support film 70 on the second electrode layer 20 of the present invention. The support film 70 supports a plurality of ultra-small LED devices so as not to be dispersed when the substrate 10 is removed through a laser lift-off (LLO) method, and also prevents cracking of the LED devices. In order to attach, the material of the support film may be a polymer exposure or bonding metal, the thickness may be 0.3 ~ 70 ㎛, but is not limited thereto.

8 illustrates an insulating film 80 formed on an outer circumferential surface including the first conductive semiconductor layer, the active layer, and the second conductive semiconductor layer with respect to the micro LED devices having the supporting film of the present invention. This minimizes defects on the surface of tiny LED devices, resulting in improved lifetime and efficiency.

The insulating film may be formed not only on the first conductive semiconductor layer 11, the active layer 12, and the second conductive semiconductor layer 13, but also on the outer circumferential surface of the first electrode layer and / or the second electrode layer and other layers.

The method of forming an insulating film on the outer circumferential surface of the micro LED devices may be a method of applying or dipping an insulating material on the outer circumferential surfaces of the micro LED devices to which the support film 70 and the substrate 10 are attached, but are not limited thereto. Do not. As a material that may be used as the insulating film, any one or more selected from the group consisting of SiO ₂ , Si ₃ N ₄ , Al ₂ O _3, and TiO ₂ may be used, but is not limited thereto. For example, the Al ₂ O ₃ film can be formed by atomic layer deposition (ALD), and trimethyl aluminum (TMA) and H ₂ O sources are supplied in the form of pulses for chemical adsorption and desorption. The thin film can be formed by using.

9 is a cross-sectional view showing a step of removing the substrate 10 formed under the first conductive semiconductor layer 11 of the LED elements of the present invention. The method of removing the substrate 10 may be a conventionally used method, preferably chemical lift-off (CLO) or laser lift-off (LLO) method. Can be used, but is not limited thereto.

10 is a cross-sectional view of manufacturing a micro LED package by forming

binders

90 and 91 on the outer circumferential surfaces of the micro LED devices on which the support film of the present invention is formed. Specifically, in FIG. 10, for example, one ultra-small LED device bundle is manufactured by treating the outer circumferential surfaces of five micro-LED devices with

binders

90 and 91. At this time, the number of the ultra-small LED elements forming one bundle may be five or more, preferably 5 to 100 in one bundle for ease of handling. The binder that can be used is not limited as long as it can form a bundle, but preferably a polymer or spin-on-glass may be used, and the polymer may be SU-8, poly (methyl methacrylate) (poly ( methylmethacrylate): PMMA), poly (4-hydroxystyrene) (poly (4-hydroxystyrene), poly (methyl glutarimide) (poly (methyl glutarimide): a photosensitive polymer such as PMGI) may be used, but is not limited thereto In addition, the binder may be hydrophobic or coated with a hydrophobic material to prevent aggregation between bundles.

On the other hand, the method of forming a plurality of bundles can be used a photolithography method when using a photosensitive polymer. First, after the photosensitive polymer is spin-coated to the first conductive semiconductor layer from which the substrate is removed, the mask may be positioned according to the photosensitive polymer type, and then ultraviolet rays may be freely left in only a desired portion. Photosensitive polymer types include a positive type and a negative type, and a mask may be positioned according to the type to remove or leave the photosensitive polymer in a desired portion, thereby forming a plurality of LED device bundles. Another method is to use a photosensitive polymer and a dry etching method to mask a portion of the photosensitive polymer to be left with a mask and ashing to remove a plurality of bundles in the desired position. In another method, similar to the above method, spin-on-glass is used instead of the photosensitive polymer to coat the first conductive semiconductor layer from which the substrate is removed, and then a plurality of LED device bundles are formed at desired positions by etching. You may. The bundle forming method is exemplary, and in addition to this, a bundle of micro LED devices may be formed through various methods.

11 is a cross-sectional view illustrating a step of forming the first electrode 110 under the first conductive semiconductor layer 11 from which the substrate 10 of the present invention is removed. The first electrode 110 may be used without limitation as long as it is a material generally used in an LED device. Preferably, the material is a single or mixed material such as Cr, Ti, Al, Au, Ni, ITO and oxides or alloys thereof. This can be used. In addition, the thickness of the electrode may be 0.02 ~ 1 ㎛, but is not limited thereto.

12 is a cross-sectional view illustrating a step of coating a coupling linker 120 for self-assembly on the surface of the first electrode 110 of the present invention. As described above, when the ultra-small LED device is so small in size, when it is attached to a subpixel (pixel seat) of the LED display substrate, there may be a problem that the ultra-small LED device does not stand upright and is lying or flipped over. In order to prevent this, the coupling linker 120 for self-assembly may be coated on the surface of the first electrode 110, and the coupling linker 12O may be coupled to a subpixel (pixel position) of the corresponding LED display substrate. If a second linker (not shown) is formed, even when the micro LED element is transferred or added to the sub pixel in the form of ink or paste, the micro LED element does not lie down or flipped, and the electrode surface is positioned on the sub pixel at a desired position. It can be attached. In addition, even if the second linker is not formed, if the functional group remaining in the coupling linker is bonded to the surface of the subpixel of the LED display substrate, the small LED device may not solve the problem of laying down or flipping.

The coupling linker must be coupled to the electrode surface of the micro LED device and the surface of the subpixel of the display substrate and / or the second linker formed on the subpixel, and thus may have two or more functional groups. Specifically, a thiol-based aminoethanethiol and an oxide reacting with a metal and an aminopropyltrirthoxysilane reacting with the metal may be used, but are not limited thereto. In addition, the second linker formed on the surface of the subpixel of the display substrate may be used without limitation as long as it can be complementarily bonded to the coupling linker of the present invention. Preferably, the same series as the coupling linker may be used.

FIG. 13 is to manufacture the independent

micro LEDs

130 and 131 by removing the support film 70. On the other hand, according to another embodiment of the present invention, the coupling linker 120 may be formed on at least one surface of the second electrode 20 and the first electrode 110 after removing the support film 70.

On the other hand, the present invention, the first conductive semiconductor layer; An active layer formed on the first conductive semiconductor layer; A plurality of micro LED devices having a diameter of a micro or nano size including a second conductive semiconductor layer formed on the active layer, the plurality of micro LED devices is a binder formed on the outer peripheral surface to form a bundle Provides a compact LED device bundle.

FIG. 14 is a perspective view illustrating a micro LED device according to the present invention. The micro LED device according to the present invention includes an active layer 141 formed on the first conductive semiconductor layer 140 and a second conductive semiconductor layer formed on the active layer 141. 142, wherein a first electrode 143 is formed under the first conductive semiconductor layer 140, and a second electrode 144 is formed on the second conductive semiconductor layer 142. Can be. Of course, as described above, a separate buffer layer, an active layer, a phosphor layer, and / or a semiconductor layer may be further included. On the other hand, the insulating film 150 to surround the active layer 141 formed on the first conductive semiconductor layer 140, including the outer peripheral surface of part or all of the second conductive semiconductor layer 142 formed on the active layer 141 Can be formed. In addition, the first and second electrodes 143 and / or the second electrode 144 may be formed to include an outer circumferential surface thereof.

Meanwhile, in order to clearly see the insulating film 80 and the semiconductor layers formed therein, the drawings of the present invention show that the insulating film and / or the binder cover only a portion of the semiconductor layer, but actually cover the entire outer circumferential surface thereof. Can be.

FIG. 15 is a perspective view illustrating the ultra-small LED device bundle of the present invention, wherein the individual micro-LED devices bundle a binder 90 around the outer circumferential surface thereof to form a bundle. As described above, the number of micro LEDs forming one bundle may be five or more. In addition, FIG. 15 illustrates only a part of the binder 90 in order to show the structure of the ultra-small LED device. In practice, the polymer binder 80 may form a bundle around the outer circumferential surface of the ultra-small LED devices. In addition, although FIG. 15 illustrates a configuration in which the insulating film 80 is formed inside the binder 90, the present invention is not limited thereto, and the binder 90 may be formed without forming the insulating film 80.

FIG. 16 is a perspective view of a micro LED device in which a coupling linker for self-assembly is formed on a surface of an electrode of the present invention. FIG. As described above, since the micro LED device is too small in size, when the micro LED device is attached to a subpixel (pixel position) of the LED display substrate, there may be a problem that the micro LED device does not stand upright and is lying or flipped over. In order to prevent this, a coupling linker 170 for self-assembly may be formed on at least one surface of the first electrode 143 and the second electrode 144. Specifically, a second linker (170) is formed on the surface of the first electrode (143) and can be coupled to the coupling linker (17O) in a subpixel (pixel position) of the LED display substrate corresponding thereto. (Not shown), the electrode surface may be attached to the sub-pixel at the desired position without lying or upside down even when the micro-LED element is transferred or added to the sub-pixel in the form of ink or paste. .

Furthermore, if the coupling linker 170 is formed on both the first electrode 143 and the second electrode 144, a part of the ultra-small LED device coupled to the subpixel (pixel position) of the LED display substrate may be the first electrode ( 143 is coupled and the second electrode 144 is coupled. In this case, when an alternating current is applied to the LED display substrate, the LED display can be driven.

The shape of the ultra-small LED device of the present invention may be formed without limitation, such as cylindrical, rectangular parallelepiped, preferably cylindrical, in the case of a cylindrical diameter (circle diameter) may be 50 ~ 3000nm, height (second Length from one electrode to the second electrode) may be 1.5 ~ 7㎛, but is not limited thereto.

17 is an ink or paste comprising the micro LED bundle of the present invention, the micro LED bundle of the present invention can be transferred directly to a subpixel of the display substrate or in the form of an ink or paste.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are only intended to help the understanding of the present invention, but are not intended to limit the scope of the present invention.

Buffered or undoped semiconductor layer (undoped GaN, 2.4-2.8 μm thick), first conductive semiconductor layer (n−) on a sapphire substrate (2 inch wafer size, 430 ± 25 μm) to manufacture an LED basic device layer (GaN) Type GaN, 2.0-2.4 μm thick), active layer (InGaN / GaN multi-quantum well, 100-140 μm), and second conductive semiconductor layer (p-type GaN, 200 nm thick) were formed using MOCVD method (FIG. 18). Reference).

The LED basic device layer manufactured as described above was manufactured as a micro LED device by the following method. First, SiO ₂ (800 nm to 1 μm thick) as an insulating layer and a chromium layer (100 to 120 nm thick) as a metal mask layer were formed on the second conductive semiconductor layer by PECVD and thermal evaporation, respectively (PECVD). _{: 60W, 550mtorr, SiH 4 160sccm} , N 2 240sccm, N 2 O 1500sccm, 35 ~ 40 minutes; thermal ^{deposition: 130 ~ 140A, 9.0x10 -6 torr} , 20 ~ 30 minutes) (see FIG. 19). Subsequently, polystyrene nanospheres were prepared as monolayer films (960-1000 nm thick) well aligned in hexagonal form and formed on the metal mask layer (see FIGS. 20A and 20B). The monolayer film was reduced to a size of 500-800 nm through an ashing process (50W, 0.05torr, O ₂ 100sccm) in an O ₂ gas atmosphere (see FIGS. 21A and 21B). Using the reduced size polystyrene nanospheres as a mask, the metal mask layer was etched under Cl ₂ gas atmosphere by RIE method (dry etching method) (50W, 0.08torr, Cl ₂ 40sccm) (see FIGS. 22A and 22B). An insulating layer portion wherein the same transfer form of polystyrene by the etching process (transfer) was prepared in the metal mask layer pattern (see Fig. 23a and 23b), by using the prepared metal mask layer pattern is present on the lower CF ₄ and O Etched again under ₂ gas atmosphere (100W, 0.042torr, CF ₄ 40sccm, O ₂ 2sccm) (see FIGS. 24A and 24B). The semiconductor layer (GaN) was etched by ICP method under SiCl ₄ and Ar gas atmosphere using the insulating layer etched by the rod pattern (RF 50W, ICP 300W, 3 torr, SiCl ₄ 2sccm, Ar 20sccm) The pattern was prepared (see FIGS. 25A and 25B). Subsequently, the insulating layer, which was used as a mask to manufacture the semiconductor layer rod pattern, was removed by etching under a CF ₄ and O ₂ gas atmosphere (see FIGS. 26A and 26B).

Atomic layer deposition (ALD) method (trimethylaluminum (TMA) as metal reactant, water vapor as oxygen source, TMA vapor pressure of 0.04 torr) The chamber temperature was maintained at 80 ° C, and Ar was used as the carrier gas and the purging gas, and an insulating film (Al ₂ O ₃ ) was coated (thickness: 20 nm) by the growth rate: ~ 1.5 kPa). As a hydrophobic coating, octadecyltrichlorosilane (OTS) was coated to a thickness of several nm. Referring to Figure 27a and 27b, it can be seen that the contact angle with water is increased by this hydrophobic coating coating. After coating the insulating film and the hydrophobic film, a supporting film was attached on the second electrode layer by using an epoxy resin (cyanoacrylate adhesive metal-type, purchased from Sigma Aldrich) (thickness: 3.5-5 μm). Subsequently, the sapphire substrate was removed by performing a lift-off process using a laser toward the buffer layer or the undoped semiconductor layer and the sapphire substrate to which the support film was not attached (see FIGS. 28A and 28B). In order to expose the first conductive semiconductor layer, the buffer layer or the undoped semiconductor layer was removed by etching by the ICP method under SiCl ₄ and Ar gas atmosphere (RF 50W, ICP 300W, 3 torr, SiCl ₄ 2sccm, Ar 20sccm), Through this process, it was possible to obtain an independent ultra-small LED rod form to which the support film was attached (see FIGS. 29A and 29B, FIGS. 30A and 30B, and FIGS. 31A and 31B).

In order to bundle the small LED rod-type devices, the supporting film was removed to some extent through an ashing process under an O ₂ gas atmosphere so that the small LED devices were exposed from the supporting film. Power 50W, working pressure 0.05torr, O ₂ 100sccm ). Subsequently, a binder (PMMA, 1.5-2.0 μm thick) to bundle the ultra-small LED devices was coated on the LED devices (see FIG. 32). After the binder coating, in order to form the electrode on the first conductive semiconductor layer, the binder is ashed and removed in an O ₂ gas atmosphere until the semiconductor layer is exposed (power 50W, working pressure 0.05torr, O ₂ 100sccm), and the electrode (Ti ) Was deposited (300V, 0.17A, Ar 100sccm) (see FIG. 33). Next, nonaneedithiol was coated on the surface of the electrode as a bonding linker by liquid or gas phase self-assembly. The coating process was performed in the liquid phase, 1mM nonanedithiol solution was prepared by mixing ethanol anhydride (10ml) and nonanedithiol (20μl), and the ultra-small LED rod form on which the electrode was deposited was added to the nonanedithiol solution. After soaking for one day, the micro LED rod was taken out and washed. The support film was removed using acetone to prepare bundled ultra-small LED devices in the form of ink or paste (see FIGS. 34A and 34B). The ink or paste was aligned by dropping onto an electrode substrate having a linker (metal fine powder: silver nanoparticles) that reacted with its binding linker (nonanedithiol linker). In the case of the electrode substrate, a pattern was formed by patterning on the electrode using silver nanoparticles, which are fine metal powders that can react with the dithiol linker reacting with the electrode substrate and the coupling linker of the micro LED. Specifically, the nonanedithiol linker was first reacted with the electrode substrate, and then coated with silver nanoparticles on the opposite side of the nonanedithiol linker, which is not attached to the electrode substrate. The coating was carried out by taking an electrode substrate having a nonanedithiol linker in a toluene solution in which silver nanoparticles were dispersed, and then removing the electrode substrate. By reacting the fine metal powder of the electrode substrate and the coupling linker of the ultra-small LED device bundle by such a process, the ultra-small LED device bundle according to the present invention is formed by forming a metal ohmic layer through a soldering process (annealing process of 100 ~ 200 ℃) Prepared (see Figure 35). Meanwhile, FIG. 36 illustrates a spectrum measured after aligning the ultra-small LED devices manufactured as described above to an electrode substrate, and also visually observed photographs of the micro LED devices manufactured in FIGS. 37A to 37C. As can be seen from the drawings, it can be seen that the blue light is emitted from the ultra-small LED device bundle according to the present invention.

The micro LED device according to the present invention can be widely used throughout the display industry.

Claims

1) sequentially forming a first conductive semiconductor layer, an active layer and a second conductive semiconductor layer on the substrate;

2) forming a plurality of ultra-small LED devices by etching the diameter of the LED device including the first conductive semiconductor layer, the active layer, and the second conductive semiconductor layer to have a nano or micro size; And

And 3) forming a plurality of bundles by forming a binder on an outer circumferential surface of the plurality of micro LEDs.

The bundle of micro LEDs of claim 1, wherein the first conductive semiconductor layer comprises at least one n-type semiconductor layer and the second conductive semiconductor layer comprises at least one p-type semiconductor layer. Manufacturing method.

The method of claim 1, wherein step 2);

2-1) sequentially forming a second electrode layer, an insulating layer, and a metal mask layer on the second conductive semiconductor layer;

2-2) forming a polymer layer on the metal mask layer and forming a pattern on the polymer layer at nano or micro intervals;

2-3) dry or wet etching the first conductive semiconductor layer, the active layer and the second conductive semiconductor layer at nano or micro intervals according to a pattern; And

2-4) The method of manufacturing the ultra-small LED device bundle comprising the step of removing the insulating layer, the metal mask layer and the polymer layer.

The method of claim 1, wherein step 2);

2-5) forming a second electrode layer, an insulating layer, and a metal mask layer on the second conductive semiconductor layer;

2-6) forming a nanosphere or microsphere monolayer on the metal mask layer and performing self-assembly;

2-7) dry or wet etching the first conductive semiconductor layer, the active layer and the second conductive semiconductor layer at nano or micro intervals according to a pattern; And

2-8) A method of manufacturing a small LED device bundle comprising the step of removing the insulating layer, the metal mask layer and the single layer film.

The method of claim 4, wherein the nanospheres or microspheres are made of polystyrene.

The method of claim 3 or 4, wherein 3) comprises:

3-1) forming a supporting film on the second electrode layer;

3-2) forming an insulating film on an outer circumferential surface including the first conductive semiconductor layer, the active layer and the second conductive semiconductor layer;

3-3) removing the substrate;

3-4) forming a plurality of bundles by forming a binder on an outer circumferential surface of the plurality of ultra-small LED elements having an insulating film formed thereon;

3-5) forming a first electrode under the first conductive semiconductor layer;

3-6) attaching a coupling linker for self-assembly to the first electrode formed under the first conductive semiconductor layer; And

3-7) Method of manufacturing a small LED device bundle comprising the step of removing the supporting film to produce a plurality of ultra-small LED device bundle.

The method of claim 1, wherein the binder is hydrophobic, and one bundle of the plurality of bundles includes 5 to 100 ultra-small LED elements.

A first conductive semiconductor layer;

An active layer formed on the first conductive semiconductor layer;

A plurality of micro LED devices having a diameter of a micro or nano size including a second conductive semiconductor layer formed on the active layer,

The plurality of ultra-small LED device is a bundle of ultra-small LED device to form a bundle by forming a binder on the outer peripheral surface.

The ultra-small LED device bundle of claim 8, wherein the binder is hydrophobic and one bundle includes 5 to 100 ultra-small LED devices.

The ultra-small LED device bundle of claim 8, wherein a first electrode layer is formed below the first conductive semiconductor layer, and a second electrode layer is formed above the second conductive semiconductor layer.

The ultra-small LED device bundle of claim 8, wherein the micro-LED device includes an insulating film formed inside the binder.

11. The micro LED bundle of claim 10, further comprising a coupling linker on a surface of at least one of the lower surface of the first electrode layer and the upper surface of the second electrode layer.

13. The ultra-small LED device bundle of claim 12, wherein the coupling linker is capable of complementarily coupling with a substrate of the LED display.

The ultra-small LED device bundle of claim 8, wherein the first conductive semiconductor layer comprises at least one n-type semiconductor layer, and the second conductive semiconductor layer comprises at least one p-type semiconductor layer.

The ultra-small LED device bundle of claim 8, wherein the binder comprises at least one material selected from the group consisting of a photosensitive polymer and spin-on-glass.