KR102524797B1 - Electrical contacts improved nano-scale LED electrode assembly and method for fabricating thereof - Google Patents

Abstract

The present invention relates to a subminiature LED electrode assembly with improved electrical contact and a manufacturing method thereof, and more particularly, to a subminiature LED electrode assembly with improved electrical contact capable of reducing contact resistance as well as increasing conductivity between an electrode and a subminiature LED element. and a method for producing the same.

Description

Electrical contacts improved nano-scale LED electrode assembly and method for fabricating the same

The present invention relates to a subminiature LED electrode assembly with improved electrical contact and a manufacturing method thereof, and more particularly, to a subminiature LED electrode assembly with improved electrical contact capable of reducing contact resistance as well as increasing conductivity between an electrode and a subminiature LED element. It is about.

In 1992, Nichia's Nakamura and others in Japan succeeded in fusing high-quality single-crystal GaN nitride semiconductors by applying a low-temperature GaN compound buffer layer, and development has been actively conducted. LED is a semiconductor having a structure in which n-type semiconductor crystals in which many carriers are electrons and p-type semiconductor crystals in which many carriers are holes are bonded to each other by using the characteristics of compound semiconductors. It is a semiconductor device that is converted into light and displayed.

These LED semiconductors have very low energy consumption due to their high light conversion efficiency, and are semi-permanent and environmentally friendly, so they are called the revolution of light as a green material. Recently, with the development of compound semiconductor technology, high-brightness red, orange, green, blue, and white LEDs have been developed, and these are used in many fields such as traffic lights, mobile phones, automobile headlights, outdoor signboards, LCD BLU (back light unit), and indoor and outdoor lighting. It has been applied in and active research is continuing at home and abroad. In particular, GaN-based compound semiconductors with a wide bandgap are materials used in the manufacture of LED semiconductors that emit light in the green, blue, and ultraviolet regions, and since white LED devices can be manufactured using blue LED devices, many studies have been conducted on this. is being done

In addition, due to the use of LED semiconductors in various fields and research on them, high-output LED semiconductors are required, and efficiency improvement of LED semiconductors has become very important. However, there are various difficulties in manufacturing a high-efficiency, high-output blue LED device.

Difficulties in improving the efficiency of blue LED devices are due to difficulties in the manufacturing process and high refractive index between the GaN-based semiconductor and the atmosphere of the manufactured blue LED.

First, the difficulty in the manufacturing process is that it is difficult to have a substrate having the same lattice constant as a GaN-based semiconductor. The GaN epitaxial layer formed on the substrate has many defects when the lattice constant of the substrate and the substrate do not match, resulting in reduced efficiency and reduced performance.

Next, due to the high refractive index of the GaN-based semiconductor of the fabricated blue LED and the atmosphere, the light emitted from the active layer region of the LED cannot escape to the outside and is totally reflected inside the LED. The total internal reflection of the light is reabsorbed internally, resulting in a decrease in the efficiency of the LED. This efficiency is called the light extraction efficiency of the LED device, and many studies are being conducted to solve this.

On the other hand, in order to utilize LED elements for lighting, displays, etc., LED elements and electrodes capable of applying power to the elements are required, and are different from LED elements in connection with the purpose of use, reduction of the space occupied by the electrodes, or manufacturing method. The placement of the two electrodes has been studied in various ways.

Research on the arrangement of LED elements and electrodes can be classified into growing LED elements on electrodes and arranging them on electrodes after independently growing LED elements separately.

First, research on growing an LED element on an electrode is to thin a lower electrode on a substrate, sequentially stack an n-type semiconductor layer, an active layer, a p-type semiconductor layer, and an upper electrode on top of it, and then etch or laminate the upper electrode before stacking the upper electrode. There is a bottom-up method in which LED elements and electrodes are simultaneously created and placed in a series of manufacturing processes through a method of laminating an upper electrode after etching the removed layers.

Next, a method of independently growing an LED element and then disposing it on an electrode is a method of individually arranging each LED element manufactured through independent growth through a separate process on a patterned electrode.

The former method has a problem in that it is crystallographically very difficult to grow a high-crystalline/high-efficiency thin film and an LED device, and in the case of the latter method, there is a problem in that light extraction efficiency is lowered and thus luminous efficiency may be lowered.

In addition, in the case of the latter method, if it is a general LED element, the three-dimensional LED element can be erected and connected to the electrode, but when the LED element is nano-sized, there is a problem that it is very difficult to erect it to the electrode. Korean Patent Application No. 2011-0040174 by the inventor of the present application consists of a bonding linker that facilitates coupling of a subminiature LED element to an electrode in order to connect a nanoscale subminiature LED element to an electrode in a three-dimensional upright manner. When implemented on a micro-electrode, there is a problem in that it is very difficult to combine the sub-miniature LED element upright with the electrode in three dimensions.

Furthermore, independently manufactured LED elements should be placed on the patterned electrodes one by one, but if the size of the LED elements is microscopic in nano units, it is very difficult to arrange the LED elements on two different microscopic electrodes within the intended range. Even if the LED element is disposed on the two electrodes, there is a problem in that the desired electrode assembly is not implemented due to frequent short-circuit electrical communication between the electrode and the subminiature LED.

Korean Patent Application No. 2010-0042321 discloses a structure and manufacturing method of an address electrode line for an LED module. In the case of the above application, a lower electrode is thinned on a substrate, an insulating layer and an upper electrode are sequentially laminated on the lower electrode, and then an electrode line is manufactured by etching, and then an LED chip is mounted on the upper electrode. However, when the LED chip to be mounted is nano-sized, there is a problem in that it is very difficult to mount the three-dimensional LED chip accurately upright on the upper electrode, and it is difficult to connect the mounted nano-sized LED chip and the lower electrode even after mounting. There is a problem.

In addition to this, when an independently grown LED element is disposed on an electrode and power is applied to the electrode, contact resistance is generated between the LED element and the electrode, thereby reducing light extraction efficiency.

The present invention has been made to solve the above problems, and the problem to be solved by the present invention is to improve the contact between the LED element and the electrode, by depositing a conductive material on the part where the LED element and the electrode are in contact, the LED element It is to provide a subminiature LED electrode assembly with improved electrical contact capable of reducing contact resistance as well as increasing conductivity between electrodes and a method for manufacturing the same.

Method for manufacturing an LED electrode assembly according to an embodiment for solving the above problems is to prepare a substrate, and form a first electrode and a second electrode spaced apart from each other on the substrate, the first electrode and the first electrode. Disposing a plurality of LED elements on two electrodes, forming a lift-off layer disposed on the plurality of LEDs and having a part of a side surface recessed, disposed on the first electrode and contacting the LED element forming a first contact electrode and a second contact electrode disposed on the second electrode and contacting the LED element, wherein the first contact electrode and the second contact electrode are respectively formed of the lift-off layer. It is formed to fill the recessed side.

A side surface of the lift-off layer may be recessed so that a width thereof may be smaller than a length of the LED device.

Forming the lift-off layer may include forming a lift-off material layer covering the plurality of LED elements, and forming a photoresist layer on the lift-off material layer, the photoresist layer and the lift-off material layer. It may include the steps of exposing and developing.

In the exposure, light may be irradiated from the upper or rear surface of the substrate.

In the exposure and development steps, the lift-off layer may be formed so that a side surface of the developed photoresist layer is depressed.

In the lift-off layer, a side surface of a portion disposed above the plurality of LED elements may be recessed.

The first contact electrode and the second contact electrode may have a thickness of 80 to 400 nm.

The LED device may include an insulating film on an outer surface.

The LED device may include an electrode layer disposed on at least one of both ends.

The first contact electrode and the second contact electrode may include a protruding portion protruding toward a portion where the first electrode and the second electrode are spaced apart.

The first contact electrode may contact a first end of the LED device, and the second contact electrode may contact a second end of the LED device.

The first contact electrode may contact an outer surface of the first end of the LED device, and the second contact electrode may contact an outer surface of the second end of the LED device.

At least a portion of the first contact electrode may be disposed on the first end of the LED element, and at least a portion of the second contact electrode may be disposed on the second end of the LED element.

The first electrode and the second electrode may each extend in a first direction and may be spaced apart from each other in a second direction different from the first direction.

The first contact electrode and the second contact electrode may each extend in the first direction and may be spaced apart from each other in the second direction.

Other embodiment specifics are included in the detailed description and drawings.

In order to improve the contact between the LED element and the electrode, the subminiature LED electrode assembly with improved electrical contact of the present invention deposits a conductive material on the part where the LED element and the electrode are in contact, thereby increasing the conductivity between the LED element and the electrode as well as increasing the contact between the LED element and the electrode. Resistance can be reduced, providing an effect of improving the light extraction efficiency of the LED device.

Effects according to the embodiments are not limited by the contents exemplified above, and more various effects are included in this specification.

1 is a perspective view showing a manufacturing process of an electrode line according to a preferred embodiment of the present invention.
2 is a perspective view of an electrode line including a first mounting electrode and a second mounting electrode formed on a base substrate according to a preferred embodiment of the present invention.
3 is a plan view of an electrode line including a first mounting electrode and a second mounting electrode formed on a base substrate according to a preferred embodiment of the present invention.
4 is a perspective view of an electrode line including a first mounting electrode and a second mounting electrode formed on a base substrate according to a preferred embodiment of the present invention.
5 is a perspective view of a subminiature LED device according to a preferred embodiment of the present invention.
6 is a cross-sectional view showing a process of forming a metal contact layer according to a preferred embodiment of the present invention.
7 is a cross-sectional view showing a process of forming a metal contact layer according to a preferred embodiment of the present invention.
8 is a cross-sectional view showing a process of forming a metal contact layer according to a preferred embodiment of the present invention.
9 is a cross-sectional view showing a process of forming a metal contact layer according to a preferred embodiment of the present invention.
10 is a perspective view of a subminiature LED electrode assembly including a developed photoresist layer according to a preferred embodiment of the present invention.
11 is a perspective view of a subminiature LED device connected to a first mounting electrode and a second mounting electrode according to an embodiment of the present invention.
12 is a SEM picture of a subminiature LED electrode assembly having a metal layer according to Comparative Example 1 of the present invention.

Advantages and features of the present invention, and methods of achieving them, will become clear with reference to the detailed description of the following embodiments taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in other forms. That is, the present invention is only defined by the scope of the claims.

When an element or layer is referred to as being "on" or "on" another element or layer, it is not only directly on the other element or layer, but also when another layer or other element is intervening therebetween. All inclusive. On the other hand, when an element is referred to as “directly on” or “directly on”, it indicates that another element or layer is not intervened.

The terms "first mounting electrode" and "second mounting electrode" used in the present invention are further included depending on the electrode area or the method of arranging the electrode on the base substrate together with the electrode area in which the subminiature LED element can be substantially mounted. It includes all possible electrode areas. However, the subminiature LED electrode assembly of the present invention means an electrode area in which a subminiature LED element can be substantially mounted.

The term "end" used in the present invention includes a part of the outer surface of the subminiature LED element that follows the end.

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

As described above, one of the LED electrode assembly manufacturing methods, a method of independently growing an LED element and then placing it on an electrode, is to arrange each LED element independently grown through a separate process on a patterned electrode. way. In the case of such a manufacturing method, when an independently grown LED element is placed on an electrode and power is applied to the electrode, contact resistance is generated between the LED element and the electrode, resulting in a problem in that the light extraction efficiency may be lowered and the luminous efficiency may be lowered. there was.

Therefore, as a first embodiment according to the present invention, (1) a subminiature LED electrode by self-aligning a subminiature LED element so that the ends of the element are respectively connected to the first mounting electrode and the second mounting electrode formed to be spaced apart in parallel with the base substrate. Manufacturing an assembly, (2) forming a photoresist layer on top of the subminiature LED electrode assembly, (3) developing the photoresist layer to expose upper surfaces of the first and second mounting electrodes. and (4) forming a metal contact layer by metal-depositing the upper part of the subminiature LED electrode assembly, and providing a method for manufacturing a subminiature LED electrode assembly with improved electrical contact to solve the above problems. Through this, by depositing a conductive material on the contact portion between the LED element and the electrode, the conductivity between the LED element and the electrode can be increased as well as the resistance value can be reduced, thereby greatly improving the light extraction efficiency of the LED element.

First, in step (1), a subminiature LED electrode assembly is manufactured by self-aligning a subminiature LED element so that one end is connected to each of the first and second mounting electrodes formed on the base substrate and spaced apart in parallel. Specifically, a dispersion solution containing a dispersion solvent and a subminiature LED element is injected into one surface of a base substrate on which an electrode line formed by separating the first and second mounting electrodes is formed, and power is applied to the electrode line to form a subminiature size. A subminiature LED electrode assembly in which the first mounting electrode and the second mounting electrode are connected is manufactured by self-aligning the LED elements.

First, a method of forming an electrode line on one surface of a base substrate will be described. Specifically, FIG. 1 is a perspective view showing a manufacturing process of an electrode line formed on a base substrate according to a preferred embodiment of the present invention. However, the manufacturing process of the electrode line for a subminiature LED device is not limited to the manufacturing process described later.

First, in FIG. 1A , any one of a glass substrate, a quartz substrate, a sapphire substrate, a plastic substrate, and a bendable flexible polymer film may be used as the base substrate 100 on which electrode lines are formed. More preferably, the base substrate 100 may be transparent. However, it is not limited to the above types, and in the case of a base substrate on which an electrode can be formed, any type may be used.

The area of the base substrate 100 is not limited, and the area of the first mounting electrode and the area of the second mounting electrode to be formed on the base substrate 100 are connected to the first mounting electrode and the second mounting electrode. It can be changed in consideration of the LED element size and the number of connected subminiature LED elements. Preferably, the base substrate 100 may have a thickness of 100 μm to 1 mm, but is not limited thereto.

Subsequently, as shown in FIG. 1B , a photo resist layer 101 may be formed by coating photo resist (PR) on the base substrate 100 . The photoresist may be a photoresist commonly used in the art. The method of forming the photoresist layer 101 by coating the photoresist on the base substrate 100 may be any one of spin coating, spray coating and screen printing, preferably spin coating, but is limited thereto It is not, and the specific method may be by a method known in the art. The photoresist layer 101 may have a thickness of 0.1 to 10 μm. However, the thickness of the photoresist layer 101 may be changed in consideration of the thickness of an electrode to be deposited on the base substrate 100 thereafter.

After the photoresist layer 101 is formed on the base substrate 100 as described above, the first mounting electrode and the second mounting electrode are spaced alternately on the same plane on the electrode line (see FIG. 3) A mask 102 on which corresponding patterns 102a and 102b are drawn is placed on the photoresist layer 101 as shown in FIG.

Thereafter, the exposed photoresist layer 101 may be immersed in a conventional photoresist solvent to remove it, and through this, a portion of the exposed photoresist layer where an electrode line is to be formed as shown in FIG. 1D may be removed. The width of the pattern 102a corresponding to the first mounting electrode line corresponding to the electrode line may be 100 nm to 50 μm, and the width of the pattern 102b corresponding to the second mounting electrode line may be 100 nm to 50 μm. It is not limited to the above description.

Subsequently, as shown in FIG. 1E , an electrode forming material 103 may be deposited in the form of an electrode line mask on the portion where the photoresist layer is removed. The electrode forming material 103 is a material for forming an electrode line including a first mounting electrode and a second mounting electrode formed to be spaced apart from the first mounting electrode, and in the case of the first mounting electrode, aluminum, titanium, indium, or gold. and at least one metal material selected from the group consisting of silver or at least one transparent material selected from the group consisting of indum tin oxide (ITO), ZnO:Al, and CNT-conductive polymer composite. When two or more types of electrode forming materials are used, the first mounting electrode may have a structure in which two or more types of materials are stacked. Even more preferably, the first mounting electrode may be an electrode in which two materials of titanium/gold are stacked. However, the first mounting electrode is not limited to the above description.

In the case of the second mounting electrode formed of the electrode forming material 103, at least one metal material selected from the group consisting of aluminum, titanium, indium, gold, and silver, or ITO (Indum Tin Oxide), ZnO:Al, and CNT-conductive polymer (polmer) It may be any one or more transparent materials selected from the group consisting of composites. When the electrode forming material 103 is two or more, preferably, the second mounting electrode may have a structure in which two or more materials are stacked. Even more preferably, the second mounting electrode may be an electrode in which two materials of titanium/gold are stacked. However, the second mounting electrode is not limited to the above description.

Materials forming the first mounting electrode and the second mounting electrode may be the same or different.

The electrode forming material may be deposited by any one of methods such as thermal evaporation, e-beam evaporation, sputtering evaporation, and screen printing, and may be preferably thermal evaporation, but is not limited thereto.

After depositing the electrode forming material to form an electrode line including a first mounting electrode and a second mounting electrode formed spaced apart from the first mounting electrode, as shown in FIG. 1F, acetone, N-methylpyrrolidone (1-Methyl -2-pyrrolidone, NMP) and dimethyl sulfoxide (Dimethyl sulfoxide, DMSO) when the photoresist layer coated on the base substrate 100 is removed using any one of the photoresist removers deposited on the base substrate 100 An electrode line 110 including a first mounting electrode 110a and a second mounting electrode 110b spaced apart from the first mounting electrode 110a may be manufactured.

In the electrode line 110 of the present invention manufactured through the above-described method, the area of the unit electrode, that is, the area of the array area where the two electrodes that can arrange and drive the subminiature LED elements independently is preferably 1 μm ² to 100 cm ² , and more preferably 10 μm ² to 100 mm ² , but the area of the unit electrode is not limited to the above area. In addition, the electrode line 110 may include one or a plurality of unit electrodes.

Furthermore, the distance between the first mounting electrode 110a and the second mounting electrode 110b in the electrode line 110 may be less than or equal to the length of the subminiature LED device. Through this, the subminiature LED element may lie between the first mounting electrode 110a and the second mounting electrode 110b and be sandwiched between the two electrodes or communicated across the two electrodes.

On the other hand, the applicable electrode line 110 of the present invention is a second mounting electrode 110b formed spaced apart on the same plane as the first mounting electrode 110a to be described later, and can be applied as long as it can mount a subminiature LED, The specific arrangement of the first mounting electrode 110a and the second mounting electrode 110b spaced apart on the same plane may vary depending on the purpose.

Next, Figure 2 is a perspective view of the electrode lines for the first mounting electrode and the second mounting electrode formed on the base substrate according to a preferred embodiment of the present invention, the first mounting electrodes (110a, 110a') and / or The two mounting electrodes 110b and 110b' may be formed on the base substrate 100 . The term "on the base substrate" means that one or more of the first mounting electrodes 110a and 110a' and the second mounting electrodes 110b and 110b' are directly formed on the surface of the base substrate 100 or the base substrate ( 100) means that it can be formed spaced apart from the top.

More specifically, in FIG. 2, both the first mounting electrodes 110a and 110a' and the second mounting electrodes 110b and 110b' are directly formed on the surface of the base substrate 100, and the first mounting electrodes 110a' and The second mounting electrodes 110b' may be alternately disposed and may be spaced apart on the same plane.

Figure 3 is a plan view of the electrode lines for the first mounting electrode and the second mounting electrode formed on the base substrate according to a preferred embodiment of the present invention, the first mounting electrodes (110a, 110c) and the second mounting electrode (110b, 110c) may be directly formed on the surface of the base substrate 100, and the first mounting electrode 110c and the second mounting electrode 110d may be spaced apart on the same plane by swirling arrangement.

As described above, when the electrode lines are alternately arranged or swirled, the driving area of the unit electrodes that can be driven independently is increased by arranging the subminiature LED elements included in the base substrate 100 of a limited area at once. Therefore, the number of subminiature LED elements mounted on the unit electrode can be increased. Since this increases the intensity of LED light emission per unit area, it can be used for various photoelectric device applications requiring high brightness per unit area.

On the other hand, FIGS. 2 and 3 are preferred embodiments, but are not limited thereto and can be variously modified and implemented with all conceivable arrangements of structures in which two electrodes are spaced apart.

In addition, unlike the electrode line according to the preferred embodiment of the present invention shown in FIG. 2, according to another preferred embodiment of the present invention, the second mounting electrode may be formed spaced apart from the top of the base substrate.

Specifically, Figure 4 is a perspective view of electrode lines for the first mounting electrode and the second mounting electrode formed on the base substrate according to a preferred embodiment of the present invention, directly on the surface of the base substrate 200, the first mounting electrode (210a) , 210a') is formed, but the second mounting electrodes 210b and 210b' are formed spaced apart from the upper part of the base substrate 200, and the first mounting electrode 210a' and the second mounting electrode 210b' are on the same plane. It may be spaced apart from each other alternately arranged on the top.

Hereinafter, a shape in which the first mounting electrode and the second mounting electrode are alternately disposed on the same plane will be described. However, the first mounting electrode and the second mounting electrode may be formed directly on the surface of the base substrate or spaced apart from the surface of the base substrate, and the first mounting electrode and the second mounting electrode may not be on the same plane.

Next, a plurality of subminiature LED elements placed on one surface of the electrode line will be described.

A plurality of subminiature LED elements may be included in a dispersion solution. A dispersion solution including a plurality of subminiature LED elements and a dispersion solvent may be prepared by mixing a plurality of subminiature LED elements in a dispersion solvent. The dispersion solvent may be in the form of ink or paste. Preferably, the dispersion solvent may be at least one selected from the group consisting of acetone, water, alcohol, and toluene, and more preferably acetone. However, the type of dispersion solvent is not limited to the above description, and any solvent that can evaporate well without physical or chemical influence on the subminiature LED device can be used without limitation.

Preferably, the subminiature LED element may be included in an amount of 0.001 to 100 parts by weight based on 100 parts by weight of the dispersion solvent. If it is included in less than 0.001 parts by weight, the normal functioning of the subminiature LED electrode assembly may be difficult due to the small number of subminiature LED elements communicating with the electrode. If it exceeds the unit, there may be a problem of disturbing the alignment between the plurality of subminiature LED elements.

On the other hand, as the subminiature LED element that can be used in the present invention, any subminiature LED element generally used for lighting or display may be used without limitation, and preferably, the length of the subminiature LED element may be 100 nm to 10 μm, and more More preferably, it may be 500 nm to 5 μm. If the length of the subminiature LED device is less than 100 nm, it is difficult to manufacture a high-efficiency LED device, and if the length exceeds 10 μm, the luminous efficiency of the LED device may be reduced. The shape of the subminiature LED device may be various shapes such as a cylinder or a rectangular parallelepiped, preferably a cylinder shape, but is not limited to the above description.

On the other hand, for the subminiature LED device according to a preferred embodiment of the present invention, Korean Patent Application No. 2011-0040174 by the inventor of the present invention may be inserted as a reference for the present invention.

Hereinafter, in the description of the subminiature LED device, 'top', 'bottom', 'top', 'bottom', 'top' and 'bottom' refer to vertical up and down directions based on each layer included in the subminiature LED device. means

The subminiature LED device includes a first mounting electrode layer, a first conductive semiconductor layer formed on the first mounting electrode layer, an active layer formed on the first conductive semiconductor layer, a second conductive semiconductor layer formed on the active layer, and the second conductive semiconductor layer. A second mounting electrode layer formed on the layer may be included.

Specifically, FIG. 5 is a perspective view showing an embodiment of a subminiature LED element included in the present invention. The subminiature LED element 20 includes a first mounting electrode layer 21 and a first conductive layer formed on the first mounting electrode layer 21. On the semiconductor layer 22, the active layer 23 formed on the first conductive semiconductor layer 22, the second conductive semiconductor layer 24 formed on the active layer 23, and the second conductive semiconductor layer 24 Including the second mounting electrode layer (25).

First, the first mounting electrode layer 21 will be described.

The first mounting electrode layer 21 may use a metal or metal oxide used as an electrode of a conventional LED device, and preferably chromium (Cr), titanium (Ti), aluminum (Al), gold (Au), nickel (Ni), ITO, oxides or alloys thereof, conductive organic materials, etc. may be used alone or in combination, but are not limited thereto. Preferably, the thickness of the first mounting electrode layer 21 may be 1 to 100 nm, but is not limited thereto.

x≤1, 0≤y≤1, 0≤x+y≤1)의 조성식을 갖는 반도체 재료 예컨대, InAlGaN, GaN, AlGaN, InGaN, AlN, InN 등에서 어느 하나 이상이 선택될 수 있으며, 제1 도전성 도펀트(예: Si, Ge, Sn 등)가 도핑될 수 있다. 바람직하게 상기 제1 도전성 반도체층(22)의 두께는 500 nm ~ 5㎛ 일 수 있으나 이에 제한되지 않는다. 상기 초소형 LED 소자(20)의 발광은 청색에 제한되지 않으므로, 발광색이 다른 경우 다른 종류의 III-V족 반도체 물질을 n형 반도체 층으로 사용하는데 제한이 없다.Next, the first conductive semiconductor layer 22 formed on the first mounting electrode layer 21 will be described. The first conductive semiconductor layer 22 may include, for example, an n-type semiconductor layer. When the subminiature LED device 20 is a blue light emitting device, the n-type semiconductor layer is In _x Al _y Ga _1-xy N (0

x≤1, 0≤y≤1, 0≤x+y≤1) may be any one or more selected from semiconductor materials having a composition formula, for example, InAlGaN, GaN, AlGaN, InGaN, AlN, InN, etc., and the first conductivity A dopant (eg, Si, Ge, Sn, etc.) may be doped. Preferably, the thickness of the first conductive semiconductor layer 22 may be 500 nm to 5 μm, but is not limited thereto. Since the light emission of the subminiature LED device 20 is not limited to blue, there is no limitation in using other types of III-V semiconductor materials as the n-type semiconductor layer when the light emission color is different.

Next, the active layer 23 formed on the first conductive semiconductor layer 22 will be described. When the subminiature LED device 20 is a blue light emitting device, the active layer 23 is formed on the first conductive semiconductor layer 22 and may have a single or multiple quantum well structure. A cladding layer (not shown) doped with a conductive dopant may be formed above and/or below the active layer 23, and the cladding layer doped with a conductive dopant may be implemented as an AlGaN layer or an InAlGaN layer. Of course, other materials such as AlGaN and AlInGaN may also be used as the active layer 23 . In this active layer 23, when an electric field is applied, light is generated by coupling of electron-hole pairs. Preferably, the active layer 23 may have a thickness of 10 to 200 nm, but is not limited thereto. The position of the active layer 23 may be formed in various positions according to the type of subminiature LED element 20 . Since the light emission of the subminiature LED device 20 is not limited to blue light, there is no limitation in using other types of III-V semiconductor materials as the active layer 23 when the light emission color is different.

x≤1, 0≤y≤1, 0≤x+y≤1)의 조성식을 갖는 반도체 물질 예컨대, InAlGaN, GaN, AlGaN, InGaN, AlN, InN 등에서 어느 하나 이상이 선택될 수 있으며, 제2 도전성 도펀트(예: Mg)가 도핑될 수 있다. 여기서, 발광 구조물은 상기 제1 도전성 반도체층(222), 상기 활성층(23), 상기 제2 도전성 반도체층(24)을 최소 구성 요소로 포함하며, 각 층의 위/아래에 다른 형광체층, 활성층, 반도체층 및/또는 전극층을 더 포함할 수도 있다. 바람직하게 상기 제2 도전성 반도체층(24)의 두께는 50 nm ~ 500 nm 일 수 있으나 이에 제한되지 않는다. 상기 초소형 LED 소자(20)의 발광은 청색에 제한되지 않으므로, 발광색이 다른 경우 다른 종류의 III-V족 반도체 물질을 p형 반도체 층으로 사용하는데 제한이 없다.Next, the second conductive semiconductor layer 24 formed on the active layer 23 will be described. When the subminiature LED device 20 is a blue light emitting device, a second conductive semiconductor layer 24 is formed on the active layer 23, and the second conductive semiconductor layer 24 includes at least one p-type semiconductor layer. It can be implemented as, wherein the p-type semiconductor layer In _x Al _y Ga _1-xy N (0

x≤1, 0≤y≤1, 0≤x+y≤1) may be any one or more selected from semiconductor materials having a composition formula, for example, InAlGaN, GaN, AlGaN, InGaN, AlN, InN, etc., and the second conductivity A dopant (eg Mg) may be doped. Here, the light emitting structure includes the first conductive semiconductor layer 222, the active layer 23, and the second conductive semiconductor layer 24 as minimum components, and other phosphor layers and active layers above/below each layer. , a semiconductor layer and/or an electrode layer may be further included. Preferably, the second conductive semiconductor layer 24 may have a thickness of 50 nm to 500 nm, but is not limited thereto. Since the light emission of the subminiature LED device 20 is not limited to blue light, there is no limitation in using other types of III-V semiconductor materials as the p-type semiconductor layer when the light emission color is different.

Next, the second mounting electrode layer 25 formed on the second conductive semiconductor layer 24 will be described.

The second mounting electrode layer 25 may use a metal or metal oxide used as an electrode of a conventional LED device, and preferably chromium (Cr), titanium (Ti), aluminum (Al), gold (Au), Nickel (Ni), ITO, oxides or alloys thereof, and conductive organic materials may be used alone or in combination, but are not limited thereto. Preferably, the second mounting electrode layer 25 may have a thickness of 1 to 100 nm, but is not limited thereto.

Meanwhile, the subminiature LED device may include an insulating film on an outer surface. Specifically, the insulating film 26 may be coated to cover the entire outer surface of the active layer 23, preferably the first conductive semiconductor to prevent degradation of durability of the subminiature LED device through damage to the outer surface of the semiconductor layer. An insulating film 26 may also be coated on the outer surface of at least one of the layer 22 and the second conductive semiconductor layer 24 .

In the method according to the first embodiment, the insulating film 26 can prevent a short circuit caused by contact between the active layer 23 of the subminiature LED element 20 and the electrode line included in the subminiature LED electrode assembly, and insulated. The film 26 may function to prevent surface defects of the active layer 23 by protecting the outer surface of the active layer 23 of the subminiature LED device 20 to prevent deterioration in luminous efficiency and durability.

Next, as step (2), a photoresist layer is formed on the subminiature LED electrode assembly.

First, a method of forming a photoresist layer on the subminiature LED electrode assembly will be described. Specifically, FIG. 6 is a cross-sectional view showing a process of forming a metal contact layer according to a preferred embodiment of the present invention.

6A shows a subminiature LED electrode assembly 300 including a subminiature LED element 303 connected to an electrode line 302 formed on a base substrate 301 . As shown in FIG. 6A, a photoresist layer 320 may be formed on the subminiature LED electrode assembly 300 including the subminiature LED element 303 connected to the electrode line 302, as shown in FIG. 6C.

Photoresist refers to a resin that undergoes chemical change when irradiated with light, and can be divided into positive photoresist and negative photoresist. Positive photoresist refers to a photosensitive resin in which the polymer is solubilized only in the portion exposed to light and the resist disappears, and negative photoresist refers to a photosensitive resin in which the polymer is insoluble only in the portion exposed to light and the resist remains.

The photoresist layer 320 may be any one selected from a positive photoresist layer and a negative photoresist layer, but it is more advantageous to simplify the process if it is preferably a negative photoresist layer.

The photoresist layer 320 can be used without limitation as long as it is a conventional method of forming the photoresist layer 320, and preferably can be coated by spin coating at 300 to 4000 rpm for 3 to 50 seconds. If it is performed at less than 300 rpm, the photoresist layer 320 may not be coated well, and if it exceeds 4000 rpm, the thickness of the photoresist layer becomes too thin, so that the lift-off may not completely proceed. can In addition, if it is performed for less than 3 seconds, the photoresist layer 320 may not be formed uniformly, and if it exceeds 50 seconds, the thickness of the photoresist layer becomes too thin, so the lift-off does not completely proceed. may occur. However, since the spin coating speed and time of the photoresist layer vary depending on the type of photoresist, it is not limited thereto.

에서 1 ~ 5 분 동안 소프트베이크(Soft bake) 하여 포토레지스트층(320)을 형성시킬 수 있다. 만일, 소프트베이크 온도가 70

미만이면 형성된 포토레지스트층(320)에 포함된 잔류 용매에 의해 노광설비 및 마스크 오염 문제가 발생할 수 있고, 110

를 초과하면 포토레지스트층(320)이 변성되거나 포토레지스트의 반응 특성이 일정하게 유지되지 않으므로 원하는 패턴을 형성할 수 없는 문제가 발생할 수 있다. 또한, 만일 소프트베이크 시간이 1분 미만이면 형성된 포토레지스트층(320)에 포함된 잔류 용매에 의해 노광설비 및 마스크 오염 문제가 발생할 수 있고, 5분을 초과하면 포토레지스트층(320)이 변성되거나 포토레지스트의 반응 특성이 일정하게 유지되지 않으므로 원하는 패턴을 형성할 수 없는 문제가 발생할 수 있다. 다만 소프트베이크 온도와 시간은 포토레지스트의 종류에 따라 다르므로 이에 제한되지 않는다.On the other hand, after coating the photoresist layer 320, the coated photoresist layer 320 is 70 to 110

The photoresist layer 320 may be formed by performing a soft bake for 1 to 5 minutes. If the soft bake temperature is 70

If it is less than 110, exposure equipment and mask contamination problems may occur due to the residual solvent included in the formed photoresist layer 320.

If it exceeds , the photoresist layer 320 may be denatured or the reaction characteristics of the photoresist may not be maintained constant, so that a desired pattern may not be formed. In addition, if the soft bake time is less than 1 minute, exposure equipment and mask contamination problems may occur due to the residual solvent included in the formed photoresist layer 320, and if the soft bake time exceeds 5 minutes, the photoresist layer 320 is denatured or Since the reaction characteristics of the photoresist are not constantly maintained, a problem in which a desired pattern cannot be formed may occur. However, since the soft bake temperature and time vary depending on the type of photoresist, it is not limited thereto.

The thickness of the soft-baked photoresist layer 320 may be 1:1.5 to 20 with respect to the diameter of the device. If the thickness of the photoresist layer is less than 1:1.5 with respect to the diameter of the device, a metal contact layer to be described later may cover the photoresist pattern and cause a problem in that lift-off does not completely proceed. If the ratio exceeds 1:20, the metal contact layer A problem of difficulty in forming a layer may occur.

Meanwhile, in step (2), a lift-off layer may be further formed between the upper portion of the subminiature LED electrode assembly and the photoresist layer. Specifically, a lift-off layer 310 may be formed on the subminiature LED electrode assembly 300 as shown in FIG. 6B. As the lift-off layer forms a step with the photoresist layer described above after step (3) described later, electrical contact to the subminiature LED element connected to the side surface of the mounting electrode can be improved. A detailed description of this will be given in step (4) to be described later. In addition, as the lift-off layer 310 has a step difference, the lift-off layer can be more easily lifted off in step (4) described later.

The lift-off layer 310 can be used without limitation as long as it is a conventional coating method of the lift-off layer 310, and preferably can be coated by spin coating at 300 to 5000 rpm for 3 to 50 seconds. If the speed is less than 300 rpm, the lift-off layer 310 may not be well coated, and if the speed exceeds 5000 rpm, the thickness of the lift-off layer may be too thin. Also, if the time is less than 3 seconds, the lift-off layer 310 may not be uniformly coated, and if the time exceeds 50 seconds, the thickness of the lift-off layer may be too thin.

에서 2 ~ 10분 동안 소프트베이크(Soft bake) 하여 리프트오프층(310)을 형성시킬 수 있다. 만일, 소프트베이크 온도가 130

미만이면 코팅된 리프트오프층(310)이 잘 고화되지 않아 포토레지스트층의 현상 시 리프트오프층이 모두 제거될 수 있는 문제가 발생할 수 있고, 180

를 초과하면 리프트오프층이 과하게 고화되거나 변성되어 현상액에 의해 리프트오프 패턴이 제대로 만들어지기 않는 문제가 발생할 수 있다. 또한, 만일 소프트베이크 시간이 2분 미만이면 코팅된 리프트오프층(310)이 잘 고화되지 않아 포토레지스트층의 현상 시 리프트오프층이 모두 제거될 수 있는 문제가 발생할 수 있고, 10분을 초과하면 리프트오프층이 과하게 고화되거나 변성되어 현상액에 의해 리프트오프 패턴이 제대로 만들어지기 않는 문제가 발생할 수 있다.On the other hand, after coating the lift-off layer 310, the coated lift-off layer 310 is 130 to 180

The lift-off layer 310 may be formed by performing a soft bake for 2 to 10 minutes. If the soft bake temperature is 130

If it is less than 180, the coated lift-off layer 310 is not well solidified, so that the lift-off layer may be completely removed during the development of the photoresist layer.

If it exceeds , the lift-off layer is excessively solidified or denatured, and a lift-off pattern may not be properly formed by the developer. In addition, if the soft bake time is less than 2 minutes, the coated lift-off layer 310 is not well solidified, so that the lift-off layer may be completely removed during the development of the photoresist layer. The lift-off layer may be excessively hardened or denatured, so that a lift-off pattern may not be properly formed by the developer.

The thickness of the soft-baked lift-off layer 310 may be 1:1 to 2 with respect to the diameter of the device. If the thickness of the lift-off layer is less than 1:1 with respect to the diameter of the device, the lift-off layer does not completely cover the device, so lift-off may be difficult, and if it exceeds 1:2, the same Even if exposure is performed for a period of time, a problem may occur unless a photoresist pattern is properly formed.

에서, 바람직하게는 300 ~ 800

에서 1 ~ 5 분간 열처리하는 단계를 더 포함할 수 있다. 상기 열처리 공정은 RTA(Rapid thermal anneling) 일 수 있는데, 상기 RTA 공정을 통하여 초소형 LED 소자의 도펀트(Dopant)를 활성화시킬 수 있고, 초소형 LED 소자가 끝단에 더 포함할 수 있는 전극의 저항을 낮추어 소자 전체저항을 낮출 수 있고, 이를 통해 전기적 컨택성이 더욱 향상된 초소형 LED 전극어셈블리를 제조할 수 있다. 한편, 반도체 소자는 도펀트의 공간 분포의 영향을 크게 받음에 따라 열처리 시간을 오래 하면 도펀트 원자들이 확산되어서 원하는 분포에서 벗어남에 따라서, 열처리 중에 반도체 내의 도펀트 원자가 이동하는 것을 최소화하기 위해서 열처리 공정으로 RTA 공정을 수행함이 바람직하다.On the other hand, according to a preferred embodiment of the present invention, the subminiature LED electrode assembly manufactured through step (1) before performing step (2) described above is 200 to 1000

, preferably from 300 to 800

A step of heat treatment for 1 to 5 minutes may be further included. The heat treatment process may be rapid thermal anneling (RTA). Through the RTA process, a dopant of the subminiature LED element may be activated, and the resistance of an electrode that may be further included at an end of the subminiature LED element may be lowered to lower the element. The total resistance can be lowered, and through this, a subminiature LED electrode assembly with further improved electrical contact can be manufactured. On the other hand, as the semiconductor device is greatly affected by the spatial distribution of dopants, if the heat treatment time is prolonged, the dopant atoms diffuse and deviate from the desired distribution. Therefore, in order to minimize the movement of dopant atoms in the semiconductor during heat treatment, the RTA process is a heat treatment process. It is desirable to perform

Next, as step (3) according to the present invention, the photoresist layer is developed so that upper surfaces of the first and second mounting electrodes are exposed.

The photoresist layer may be developed by two methods, back exposure and direct lithography, so that upper surfaces of the first and second mounting electrodes are exposed.

에서 1 ~ 2 분 동안 열처리할 수 있다. 만일 상기 UV 조사 시간이 3초 미만이면 노광된 영역이 모두 불용성이 되지 않는 문제가 발생할 수 있고, 30초를 초과하면 제1 실장전극 및 제2 실장전극 상부의 포토레지스트층까지 노광 영역이 확장되어 전기적 컨택 향상 효과를 기대하기 어려운 문제가 발생할 수 있다. 다만 상기 UV 조사 시간은 조사되는 UV의 광량에 따라 다르므로 이에 제한되지 않는다. 또한, 상기 열처리 온도가 90

미만이면 노광과 관계없이 현상액에 의해 포토레지스트층이 제거되는 문제가 발생할 수 있고, 130

를 초과하면 포토레지스트층이 과하게 고화되거나 변성되어 현상이 어려운 문제가 발생할 수 있다. 또한, 상기 열처리 시간이 1분 미만이면 노광과 관계없이 현상액에 의해 포토레지스트층이 제거되는 문제가 발생할 수 있고, 2분을 초과하면 포토레지스트층이 과하게 고화되거나 변성되어 현상이 어려운 한 문제가 발생할 수 있다.First, a back exposure method will be described. Specifically, the photoresist layer may be developed to expose upper surfaces of the first mounting electrode and the second mounting electrode by a back exposure method as shown in FIG. 6D. More specifically, when using the back exposure method, the photoresist layer may be a negative photoresist layer, and exposure of the lift-off layer 310 and the photoresist layer 320 by irradiating UV from the bottom of the subminiature LED electrode assembly 300 area can be insolubilized. Meanwhile, the UV irradiation may be irradiated for 3 to 30 seconds, and after the UV irradiation, 90 to 130

heat treatment for 1 to 2 minutes. If the UV irradiation time is less than 3 seconds, there may be a problem that the exposed area is not all insoluble, and if it exceeds 30 seconds, the exposure area is extended to the photoresist layer above the first mounting electrode and the second mounting electrode. A problem in which it is difficult to expect an electrical contact improvement effect may occur. However, the UV irradiation time is different depending on the amount of UV light to be irradiated, so it is not limited thereto. In addition, the heat treatment temperature is 90

If it is less than 130, the photoresist layer may be removed by the developer regardless of exposure.

If it exceeds , the photoresist layer may be excessively solidified or denatured, resulting in difficult development problems. In addition, if the heat treatment time is less than 1 minute, a problem in that the photoresist layer is removed by the developer regardless of exposure may occur, and if it exceeds 2 minutes, the photoresist layer is excessively solidified or denatured, causing problems as long as development is difficult. can

Next, a direct lithography method will be described. Specifically, FIG. 7 is a cross-sectional view showing a process of forming a metal contact layer according to a preferred embodiment of the present invention. Unlike the backside exposure method of FIG. 6D described above, as shown in FIG. can be investigated 7d is a step of directly lithographically irradiating UV using a negative photoresist as the photoresist layer, which has a width equal to or less than that of the mounting electrode 402 on top of the photoresist layer 420. A mask 404 may be formed, and exposed regions of the lift-off layer 410 and the photoresist layer 420 may be insolubilized by irradiating UV light on an upper portion of the mask 404 . On the other hand, when UV is directly irradiated by a lithography method using a positive photoresist as the photoresist layer, a mask (not shown) may be formed on the photoresist layer (not shown) differently from FIG. 7D, and more specifically A mask (not shown) corresponding to the separation space between the first mounting electrode (not shown) and the second mounting electrode (not shown) formed on the base substrate (not shown) on top of the photoresist layer (not shown). Formed and irradiated with UV from the top of the mask (not shown), the exposed regions of the lift-off layer (not shown) and the photoresist layer (not shown) may be solubilized.

에서 1 ~ 3 분 동안 열처리할 수 있다. 만일 상기 UV 조사 시간이 3초 미만이면 노광된 영역이 모두 불용성이 되지 않는 문제가 발생할 수 있고, 30초를 초과하면 제1 실장전극 및 제2 실장전극 상부의 포토레지스트층까지 노광 영역이 확장되어 전기적 컨택 향상 효과를 기대하기 어려운 문제가 발생할 수 있다. 다만 상기 UV 조사 시간은 조사되는 UV의 광량에 따라 다르므로 이에 제한하지 않는다. 또한, 상기 열처리 온도가 90

미만이면 노광과 관계없이 현상액에 의해 포토레지스트층이 제거되는 문제가 발생할 수 있고, 130

를 초과하면 포토레지스트층이 과하게 고화되거나 변성되어 현상이 어려운 문제가 발생할 수 있다. 또한, 상기 열처리 시간이 1분 미만이면 노광과 관계없이 현상액에 의해 포토레지스트층이 제거되는 문제가 발생할 수 있고, 3분을 초과하면 포토레지스트층이 과하게 고화되거나 변성되어 현상이 어려운 문제가 발생할 수 있다.The UV irradiation may be irradiated for 3 to 30 seconds, and after the UV irradiation, 90 to 130

can be heat treated for 1 to 3 minutes. If the UV irradiation time is less than 3 seconds, there may be a problem that the exposed area is not all insoluble, and if it exceeds 30 seconds, the exposure area is extended to the photoresist layer above the first mounting electrode and the second mounting electrode. A problem in which it is difficult to expect an electrical contact improvement effect may occur. However, the UV irradiation time is different depending on the amount of UV light to be irradiated, so it is not limited thereto. In addition, the heat treatment temperature is 90

If it is less than 130, the photoresist layer may be removed by the developer regardless of exposure.

If it exceeds , the photoresist layer may be excessively solidified or denatured, resulting in difficult development problems. In addition, if the heat treatment time is less than 1 minute, a problem in that the photoresist layer is removed by the developer regardless of exposure may occur, and if it exceeds 3 minutes, the photoresist layer is excessively solidified or denatured, resulting in difficult development. there is.

Thereafter, the lift-off layer 310 and the photoresist layer 320 may be developed as shown in FIG. 6E. Specifically, the lift-off layer 311 and the photoresist layer 321 may be developed to expose upper surfaces of the first and second mounting electrodes, and the remaining photoresist layer 321 and lift-off A side surface of the layer 311 may be depressed to form a step between the photoresist layer 321 and the lift-off layer 311 .

Any developing solution used in the development in step (3) may be used without limitation as long as it is a developing solution that is normally used for development, and preferably tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, hydroxide Tetrabutylammonium, methyltriethylammonium hydroxide, trimethylethylammonium hydroxide, dimethyldiethylammonium hydroxide, trimethyl(2-hydroxyethyl)ammonium hydroxide, triethyl(2-hydroxyethyl)ammonium hydroxide, dimethyldi(2-hydroxyethyl)ammonium hydroxide Hydroxyethyl) ammonium, diethyl (2-hydroxyethyl) ammonium hydroxide, methyl tri (2-hydroxyethyl) ammonium hydroxide, ethyl tri (2-hydroxyethyl) ammonium hydroxide, tetra (2-hydroxyethyl) hydroxide ) Any one selected from ammonium and potassium hydroxide (KOH) may be used, and more preferably tetramethylammonium hydroxide (TMAH) may be used.

Step (3) may be performed in the developing solution for 30 to 300 seconds, preferably 60 to 240 seconds. If the development time is less than 30 seconds, the lift-off layer 310 and the photoresist layer 320 are not developed well, and a problem of difficulty in forming a pattern may occur. If the development time exceeds 300 seconds, lift-off regardless of exposure may occur. A problem may occur in which both the photoresist layer and the photoresist layer are developed and removed.

Meanwhile, in step (3), the photoresist layer 321 may be developed so that upper portions of both ends of the subminiature LED element 303 are further exposed. Specifically, FIG. 10 is a perspective view of a subminiature LED electrode assembly including a developed photoresist layer according to a preferred embodiment of the present invention, with mounting electrodes formed spaced apart on the base substrate 301 through the performance of step (3). The lift-off layer 311 and the photoresist layer 321a remaining on the upper surface of the region between 302 and 302' are shown. In FIG. 10, a plurality of subminiature LED elements 303 are connected to the mounting electrode 302, and the photoresist layer 321a on the top of the area where the subminiature LED element 303 is connected to the mounting electrode 302 is a subminiature LED element. It can be seen that both ends of 303 are developed to be further exposed. This is because UV reaches the subminiature LED element 303 earlier than the photoresist layer 321a during back exposure and is absorbed, so the photoresist layer located on the electrode part where the subminiature LED element 303 is relatively located. This is because the UV irradiation amount of (321a) was reduced and was not insolubilized and was removed during development. Through this, it may be more advantageous to form a metal contact layer during metal deposition in the subsequent step (4).

On the other hand, the side surfaces of the photoresist layer 321a and the lift-off layer 311 remaining after development are depressed so that there is a step ( A) can be formed. The step (A) will be described in step (4) to be described later.

A length ratio between the widths of the photoresist layer remaining after the development and the width of the lift-off layer may be 1:0.2 to 0.8.

Meanwhile, the ratio of the length to the width of the photoresist layer 321a remaining after the development and the lift-off layer 311 having the step A may be 1:0.2 to 0.8. If the ratio of the width to the length of the photoresist layer 321a remaining after the development and the lift-off layer 311 formed with the step A is less than 1:0.2, the lift-off layer cannot withstand and the pattern collapses. , 1: If the ratio exceeds 0.8, lift-off does not work well, and contact properties of the subminiature LED element mounted on the side may not be improved.

Meanwhile, the length of the width of the lift-off layer may be the shortest width of the lift-off layer 311 on which the step A is formed.

Next, as step (4), a metal contact layer is formed by depositing metal on the top of the subminiature LED electrode assembly.

Step (4) includes (4-1) forming a metal contact layer by metal-depositing the top of the subminiature LED electrode assembly including the upper surface of the photoresist layer, and (4-2) lifting off the photoresist. can include

First, in step (4-1) of forming a metal contact layer by metal-depositing the upper surface of the subminiature LED electrode assembly including the upper surface of the photoresist layer, a part of the recessed part of the lift-off layer 311 as shown in FIG. 6F The metal deposition layer 330 may be formed by burying it. This is because in step (3), a step is formed between the photoresist layer 321a and the lift-off layer 311 as shown in FIG. It is possible to more easily form a metal contact layer between the subminiature LED element and the mounting electrode, which are inserted into and connected to the side surfaces of the different mounting electrodes, than when in use. If the lift-off layer 311 is not included, since the level difference (A) does not occur, both ends of the subminiature LED element 303 connected to the spaced side surfaces of the mounting electrode when the upper part of the subminiature LED electrode assembly is metal-deposited. Including a metal deposition layer (not shown) may cause a difficult problem to form.

In detail, as the lift-off layer is formed, electrical contact of subminiature LED elements connected to side surfaces of mounting electrodes other than some subminiature LED elements may be improved.

11 is a perspective view of a subminiature LED element connected to a first mounting electrode and a second mounting electrode according to an embodiment of the present invention. Looking at the alignment of a plurality of subminiature LED elements 703a to 703d in a subminiature LED electrode assembly, The first subminiature LED element 703a and the fourth subminiature LED element 703d are aligned so that the mounting electrode and the longitudinal direction of the device are perpendicular to each other, but the second subminiature LED element 703b is on the side of the mounting electrode. It is slanted and connected. In addition, the first sub-miniature LED element 703a and the second sub-miniature LED element 703b are inserted into and connected to the side surfaces of two different mounting electrodes, whereas the third sub-miniature LED element 703c has one end on the side of the electrode and one end on the electrode. connected to the upper surface of the fourth subminiature LED element 703d, both ends of the element are connected to the upper surfaces of two different mounting electrodes, and it can be confirmed that the alignment of the plurality of subminiature LED elements mounted on the electrode line is irregular. there is. Since this is physically subminiature, it is impossible to mount each subminiature LED element in a desired direction on the electrode line by machine or human hand, and even through the conventional method by the present inventor, the directionality of the subminiature LED element is It's because it's very difficult to fit everything neatly.

In addition, when the metal deposition layer 704 is formed only on the upper portions of the first mounting electrode 702a and the second mounting electrode 702b as shown in FIG. 11, the subminiature LED elements 703a and 703b connected to the side surfaces of the mounting electrode 702 Since the metal contact layer 704 is not formed at both ends of the subminiature LED element, only the subminiature LED element 703d, both ends of which are connected to the top of the mounting electrode 702, can improve electrical contact. In step (3), as the lift-off layer is depressed, and a step difference is generated between the photoresist layer and the lift-off layer, in step (4), unlike FIG. An effect of forming a contact layer can be obtained.

Next, in step (4-2) of lifting off the photoresist, the lift-off layer 311 and the photoresist layer 321 formed on the lift-off layer 311 can be lifted off as shown in FIG. 6G. . 10, as a step is formed between the photoresist layer 321a and the lift-off layer 311 in step (3), after forming the metallization layer 330 in step (4), the photoresist layer 321a is formed. When the lift-off layer 311 is lifted off, the lift-off layer 311 can be lifted off more easily than when the lift-off layer 311 is used alone. If the lift-off layer 311 is not included, since the step A does not occur, the photoresist layer 321a and a metal deposition layer (not shown) formed on the upper surface of the photoresist layer 321a A problem that is difficult to lift off may occur. Specifically, in order to lift off the photoresist layer 321a without the lift-off layer 311, the lower surface of the photoresist layer 321a should be in the form of an inverted triangle with a shorter width than the upper surface of the photoresist layer 321a. Since it is unreasonable to form a photoresist layer having a shape, a problem in that the remaining photoresist layer 321a cannot be easily lifted off may occur.

In step (4-2), the metallization layer 330 lifts off the lift-off layer 311, so that the metallization layer 330a formed on the upper surface of the photoresist layer 321 is formed on the lift-off layer 311 and It is removed together with the photoresist layer 321, and as shown in FIG. 6G, only the metallization layer 330b formed on the mounting electrode 302 including both ends of the subminiature LED element 303 remains.

Meanwhile, in the second embodiment according to the present invention, (1) the subminiature LED electrode is self-aligned so that the ends of the element are connected to the first mounting electrode and the second mounting electrode formed to be spaced apart in parallel with the base substrate, respectively. Manufacturing an assembly, (2) forming a metallization layer on top of the subminiature LED electrode assembly, (3) forming a photoresist layer on top of the metallization layer, (4) first mounting electrode and (5) developing the photoresist layer so that at least a portion of the photoresist layer portion corresponding to the separation space between the second mounting electrodes is removed to expose the upper surface of the metallization layer, and (5) the removed photoresist layer area. It provides a method for manufacturing a micro LED electrode assembly with improved electrical contact, including the step of forming a metal contact layer by etching the metallization layer corresponding to .

8 is a cross-sectional view showing a process of forming a metal contact layer according to a preferred embodiment of the present invention. The step (1) of FIG. 8A is the same as the description of the step (1) of the above-described manufacturing method, so a detailed description thereof will be omitted.

Next, as step (2), a metal deposition layer is formed on the subminiature LED electrode assembly.

Unlike the first embodiment described above, the second embodiment according to the present invention directly forms a metallization layer without a photoresist layer on the electrode assembly after step (1), which is a subminiature LED manufactured in step (1). This is because the placement and alignment of the subminiature LEDs on the mounting electrodes of the electrode assembly depend on the self-alignment of the elements by the application of power, so mechanical and uniform arrangement cannot be achieved, and accordingly, the metal contact layer is accurately formed in the desired area. because it's hard to be

Specifically, Figure 11 is a perspective view of a subminiature LED element connected to a first mounting electrode and a second mounting electrode according to an embodiment of the present invention, looking at the alignment of the subminiature LED element in the subminiature LED electrode assembly, mounted on the electrode line It can be confirmed that the alignment of the plurality of subminiature LED elements is irregular. Since this is physically subminiature, it is impossible to mount each subminiature LED element in a desired direction on the electrode line by machine or human hand, and even through the conventional method by the present inventor, the directionality of the subminiature LED element is It's because it's very difficult to fit everything neatly.

Therefore, in order to form the metal contact layer at both ends of the irregularly aligned subminiature LED elements as described above, after performing step (1), a metallization layer is formed on the subminiature LED electrode assembly. If the metal deposition layer 704 is formed only on the upper portions of the first mounting electrode 702a and the second mounting electrode 702b as shown in FIG. 11, both ends of the subminiature LED device are connected to the upper portion of the mounting electrode 702. Only the fourth subminiature LED element 703d can have improved electrical contact, and one end or both ends of the element is connected to the side surface of the mounting electrode 702. The first subminiature LED element 703a to the third subminiature LED element ( In the case of 703c), there is a problem that the metal contact layer may not be formed.

Specifically, as shown in FIG. 8B, a metal deposition layer 510 is formed on the subminiature LED electrode assembly 500 including the subminiature LED element 503 connected to the mounting electrode 502 spaced apart from the top of the base substrate 501. let it Any metal that can be used in forming the metallization layer 510 may be used without limitation as long as it is a metal commonly used for metallization, and preferably titanium (Ti), gold (Au), chromium (Cr), and aluminum (Al). ), it is more advantageous to improve the electrical contact of the subminiature LED electrode assembly.

Meanwhile, due to the above step (2), a metallization layer is also formed on the side surface including the active layer of the subminiature LED device, and then, when there is residual metal electrically connecting the first conductive semiconductor layer and the second conductive semiconductor layer, a short circuit is formed. may occur, resulting in a short circuit in the electrode. Accordingly, the subminiature LED device preferably includes an insulating film.

Specifically, as shown in FIG. 5 , the subminiature LED device 20 according to the present invention may include an insulating film 26 on an outer surface except for both ends of the subminiature LED device 20 . The insulating film 26 of the subminiature LED element included in the manufacturing method according to the second embodiment is directly formed on the outer surface of the subminiature LED element through the above-described step (2) in addition to the purpose described in the first embodiment. As the metallization layer is not etched to the desired level in step (5), it is possible to fundamentally prevent electrical short circuit problems of the subminiature LED element that may occur in case of emergency remaining on the outer surface of the subminiature LED element. . Specifically, after the etching process in step (5), when there is residual metal connecting the first conductive semiconductor layer and the second conductive semiconductor layer of the subminiature LED device, a short circuit may occur and a short circuit may occur in the electrode. The insulating film ( 26) can prevent this.

Next, as step (3), a photoresist layer 520 is formed on top of the metallization layer.

As shown in FIG. 8C, the photoresist layer 520 is formed on top of the metallization layer 510 formed in step (2).

The photoresist layer 520 can be used without limitation as long as it is a conventional coating method of the photoresist layer 520, and preferably can be coated by a spin coating method at 300 to 4000 rpm for 3 to 50 seconds. If it is performed at less than 300 rpm, the photoresist layer 320 may not be coated well, and if it exceeds 4000 rpm, the thickness of the photoresist layer becomes too thin, so that the lift-off may not completely proceed. can In addition, if it is performed for less than 3 seconds, a problem that the photoresist layer 320 is not uniformly coated may occur, and if it exceeds 50 seconds, the thickness of the photoresist layer becomes too thin, so that the lift-off does not completely proceed. may occur. However, since the spin coating speed and time of the photoresist layer vary depending on the type of photoresist, it is not limited thereto.

에서 1 ~ 5 분 동안 소프트베이크(Soft bake) 하여 포토레지스트층(520)을 고화시킬 수 있다.On the other hand, after coating the photoresist layer 520, in order to solidify the coated photoresist layer 520, 70 to 110

The photoresist layer 520 may be solidified by performing a soft bake for 1 to 5 minutes.

미만이면 형성된 포토레지스트층(320)에 포함된 잔류 용매에 의해 노광설비 및 마스크 오염 문제가 발생할 수 있고, 110

를 초과하면 포토레지스트층(320)이 변성되거나 포토레지스트의 반응 특성이 일정하게 유지되지 않으므로 원하는 패턴을 형성할 수 없는 문제가 발생할 수 있다. 또한, 만일 소프트베이크 시간이 1분 미만이면 형성된 포토레지스트층(320)에 포함된 잔류 용매에 의해 노광설비 및 마스크 오염 문제가 발생할 수 있고, 5분을 초과하면 포토레지스트층(320)이 변성되거나 포토레지스트의 반응 특성이 일정하게 유지되지 않으므로 원하는 패턴을 형성할 수 없는 문제가 발생할 수 있다. 다만 소프트베이크 온도와 시간은 포토레지스트의 종류에 따라 다르므로 이에 제한하지 않는다.If the soft bake temperature is 70

If it is less than 110, exposure equipment and mask contamination problems may occur due to the residual solvent included in the formed photoresist layer 320.

If it exceeds , the photoresist layer 320 may be denatured or the reaction characteristics of the photoresist may not be maintained constant, so that a desired pattern may not be formed. In addition, if the soft bake time is less than 1 minute, exposure equipment and mask contamination problems may occur due to the residual solvent included in the formed photoresist layer 320, and if the soft bake time exceeds 5 minutes, the photoresist layer 320 is denatured or Since the reaction characteristics of the photoresist are not constantly maintained, a problem in which a desired pattern cannot be formed may occur. However, since the soft bake temperature and time vary depending on the type of photoresist, it is not limited thereto.

The thickness of the soft-baked photoresist layer 520 may have a thickness of 1:1.5 to 20 with respect to the diameter of the device. If the thickness of the photoresist layer is less than 1:1.5 with respect to the diameter of the device, only the desired metal contact layer cannot be etched as the photoresist layer is etched together in the metal contact layer etching process to be performed in a later step, and 1: If it exceeds 20, it becomes difficult to remove the photoresist layer denatured in the etching process.

Next, in step (4), the photoresist layer is developed so that at least a portion of the photoresist layer corresponding to the separation space between the first mounting electrode and the second mounting electrode is removed to expose the upper surface of the metallization layer.

Specifically, in the case of forming a negative photoresist layer on top of the metallization layer 510, after curing the photoresist layer 520 as described above, the first mounting electrode and the first mounting electrode and the first mounting electrode on the top of the photoresist layer as shown in FIG. 8D. The exposed area of the photoresist layer 520 may be insolubilized by forming a mask 504 corresponding to the separation space between the two mounting electrodes and irradiating UV with a direct lithography method. The UV irradiation may be irradiated for 0.3 to 30 seconds, preferably for 0.5 to 15 seconds. If the UV irradiation time is less than 0.3 seconds, the exposed area is not all insoluble, and a problem of exposing the subminiature LED element during development may occur. If the UV irradiation time exceeds 30 seconds, the photoresist whose exposed area is excluded by the mask 504 A problem of exposure to layer 520 may occur. However, the UV irradiation time is different depending on the amount of UV light to be irradiated, so it is not limited thereto.

Meanwhile, FIG. 9 is a cross-sectional view showing a process of forming a metal contact layer according to a preferred embodiment of the present invention. When a positive photoresist layer is formed on top of a metallization layer, the photoresist layer 620 is cured as described above. 9d, a mask 604 corresponding to the spaces of the first mounting electrode and the second mounting electrode is formed on the top of the photoresist layer 620 as shown in FIG. The exposed areas of layer 620 may be solubilized. The UV irradiation may be irradiated for 0.5 to 30 seconds, preferably for 2 to 15 seconds. If the UV irradiation time is less than 0.5 seconds, the exposed area may not all be soluble, causing a problem of not forming a pattern, and if it exceeds 30 seconds, the photoresist (620) above the first and second mounting electrodes ), a problem in which the subminiature LED element 603 is exposed during development may occur.

Thereafter, the photoresist layer 520 may be developed as shown in FIG. 8E. Specifically, the photoresist layer 520 corresponding to the separation space between the first mounting electrode and the second mounting electrode may be developed, and accordingly, the photoresist layer 521 remaining after development may be used for the first mounting electrode and the second mounting electrode. The photoresist layer corresponding to the separation space between the second mounting electrodes may be removed.

Any developing solution used in the development in step (4) may be used without limitation as long as it is a developing solution commonly used for development, and preferably tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, hydroxide Tetrabutylammonium, methyltriethylammonium hydroxide, trimethylethylammonium hydroxide, dimethyldiethylammonium hydroxide, trimethyl(2-hydroxyethyl)ammonium hydroxide, triethyl(2-hydroxyethyl)ammonium hydroxide, dimethyldi(2-hydroxyethyl)ammonium hydroxide Hydroxyethyl) ammonium, diethyl (2-hydroxyethyl) ammonium hydroxide, methyl tri (2-hydroxyethyl) ammonium hydroxide, ethyl tri (2-hydroxyethyl) ammonium hydroxide, tetra (2-hydroxyethyl) hydroxide ) Any one selected from ammonium and potassium hydroxide (KOH) may be used, and more preferably tetramethylammonium hydroxide (TMAH) may be used.

Meanwhile, in the case of forming the negative photoresist layer, the development time may be 30 to 120 seconds, preferably 45 to 105 seconds. If the development time is less than 30 seconds, the photoresist layer 520 may not develop well, and if it exceeds 120 seconds, the photoresist layer 520 is excessively developed, resulting in etching of the metallization layer to be described later. A problem affecting the subminiature LED element 503 may occur.

In addition, in the case of forming a positive photoresist layer, the development time may be 15 to 75 seconds, preferably 30 to 60 seconds. If the development time is less than 15 seconds, the photoresist layer 620 may not develop well, and if it exceeds 75 seconds, the photoresist layer 620 is excessively developed, resulting in etching of the metallization layer to be described later. Problems affecting the subminiature LED element 603 may occur.

Meanwhile, in step (4), at least a portion of the photoresist layer corresponding to the separation space between the first mounting electrode and the second mounting electrode may be removed. In other words, the photoresist layer may be developed with a narrower width than the separation space.

Examining the alignment of the subminiature LED elements in the subminiature LED electrode assembly shown in FIG. 11, it can be seen that the alignment of the plurality of subminiature LED elements mounted on the electrode line is irregular.

In addition, when the metal deposition layer 704 is formed only on the upper portions of the first mounting electrode 702a and the second mounting electrode 702b as shown in FIG. 11, the subminiature LED elements 703a and 703b connected to the side surfaces of the mounting electrode 702 Since the metal contact layer 704 is not formed at both ends of the ( In step 4), at least a portion of the photoresist layer corresponding to the separation space between the first mounting electrode and the second mounting electrode is removed, so that, unlike FIG. The effect of forming a layer can be obtained.

Next, in step (5), the metallization layer corresponding to the removed photoresist layer region is etched to form a metal contact layer.

The step (5) includes (5-1) forming a metal contact layer by etching the metallization layer so that only the metallization layer corresponding to the removed photoresist layer area is removed, and (5-2) the etched subminiature metallization layer. It may include removing the photoresist on top of the LED electrode assembly.

First, in step (5-1) of forming a metal contact layer by etching the metallization layer so that only the metallization layer corresponding to the removed photoresist layer area is removed, as shown in FIG. 8F, the removed photoresist layer area A metal deposition layer corresponding to may be etched.

The etching can be used without limitation as long as it is a method commonly used for metal etching, preferably a dry etching method and a wet etching method, and more preferably using a dry etching method is more advantageous for etching in a certain direction do. In addition, the dry etching can be used without limitation as long as it is a gas normally used for dry etching, preferably any one gas selected from CF ₄ and Cl ₂ can be used, and in the case of using CF ₄ , 40 to 120 sccm , 90 to 110 W and 0.040 to 0.070 Torr, and when using Cl ₂ , it can be performed under the conditions of 10 to 30 sccm, 70 to 90 W and 0.06 to 0.1 Torr.

Next, in step (5-2) of removing the etched photoresist on top of the subminiature LED electrode assembly, the photoresist layer 521 on top of the subminiature LED electrode assembly may be removed as shown in FIG. 8G.

* 159 In order to remove the photoresist layer 521, the subminiature LED electrode assembly is put into a photoresist remover (PR remover) to remove the photoresist layer 521, which is a commonly used photoresist remover. Any resist remover can be used without limitation, preferably containing 2-(2-aminoethoxy), ethanol, hydroxylamine and catechol. Any one selected from a mixed solution (EKC 265 polymer, DuPont), acetone, N-methylpyrrolidone (1-Methyl-2-pyrrolidone, NMP), and dimethyl sulfoxide (DMSO) may be used, and more preferably Preferably, EKC 265 polymer can be used.

에서 상기 초소형 LED 전극 어셈블리를 포토레지스트 리무버에 5 ~ 30 분 동안 넣어서 수행할 수 있다. 만일 온도가 55

미만이면 포토레지스트 리무버의 반응성이 낮기 때문에 포토레지스트층이 잘 제거가 되지 않는 문제가 발생할 수 있고, 온도가 75

를 초과하면 초소형 LED 소자 및 전극에 문제가 발생할 수 있다. 또한, 5분 미만으로 수행할 경우 포토레지스트층이 완전히 제거되지 않는 문제가 발생할 수 있고, 30분을 초과할 경우 초소형 LED 소자 및 전극에 문제가 발생할 수 있다.On the other hand, the step (5-2) is 55 to 75

It can be performed by putting the subminiature LED electrode assembly in a photoresist remover for 5 to 30 minutes. If the temperature is 55

If it is less than 75 degrees, the photoresist layer may not be removed well because the reactivity of the photoresist remover is low.

If it exceeds, problems may occur in the subminiature LED element and electrode. In addition, when performed for less than 5 minutes, a problem may occur in which the photoresist layer is not completely removed, and when it exceeds 30 minutes, problems may occur in the subminiature LED device and the electrode.

The present invention relates to a base substrate, an electrode line including a first mounting electrode and a second mounting electrode formed to be spaced apart from each other in parallel with the base substrate, and a plurality of electrode lines having ends of elements connected to the first mounting electrode and the second mounting electrode, respectively. Subminiature LED element with improved electrical contact including a metal contact layer formed to cover the upper surface of the subminiature LED element and the mounting electrode including regions corresponding to the connection portions between the first and second mounting electrodes and the subminiature LED element An electrode assembly is provided. Specifically, a subminiature LED electrode assembly having improved electrical contact including a metal contact layer as shown in FIGS. 6g, 7g, 8g, and 9g is provided.

According to a preferred embodiment of the present invention, the metal contact layer may have a thickness of 80 to 400 nm based on the upper surface of the mounting electrode. If the thickness of the metal contact layer is less than 80 nm, since the thickness of the metal contact layer is too thin, it is impossible to completely cover one end of the subminiature LED element with irregular alignment, so it is difficult to expect electrical contact improvement. If it exceeds , the metal contact layer is etched and the metal is redeposited on the side surface of the photoresist layer, which may cause an electrical short circuit.

On the other hand, the subminiature LED device may include an insulating film on the outer surface except for both ends, Residual metal derived from the metal contact layer may be included on an outer surface of the subminiature LED device that does not belong to a region corresponding to a connection portion between the first and second mounting electrodes and the subminiature LED device. When residual metal derived from the metal contact layer is present on the outer surface of the subminiature LED element that does not belong to the corresponding area when the insulating film is not included, an electrical short occurs as a short circuit occurs, and the subminiature LED device connected to the mounting electrode Although there may be a problem that the LED element does not occur, since the subminiature LED element of the present invention includes an insulating film, it is possible to prevent the above problem from occurring.

Although the present invention has been described above with reference to the drawings, this is only an example and does not limit the embodiments of the present invention, and those skilled in the art to which the embodiments of the present invention belong will not deviate from the essential characteristics of the present invention. It will be appreciated that various modifications and applications not exemplified above are possible within a range not specified. For example, each component specifically shown in the embodiment of the present invention can be modified and implemented. And differences related to these variations and applications should be construed as being included in the scope of the present invention as defined in the appended claims.

Hereinafter, the present invention will be described through the following examples. At this time, the following examples are only presented to help understand the invention and illustrate the invention, and the scope of the present invention is not limited by the following examples.

Example

Preparation Example 1

An electrode line as shown in FIG. 2 was prepared on a quartz base substrate having a thickness of 850 μm. At this time, in the electrode line, the width of the first mounting electrode is 3 μm, the width of the second mounting electrode is 3 μm, the distance between the first mounting electrode and the adjacent second mounting electrode is 2.5 μm, and the thickness of the electrode is 0.2 μm. The material of the first mounting electrode and the second mounting electrode was titanium/gold, and the area of the region where the subminiature LED element was mounted in the electrode line was 4.2 x 10 ⁷ ㎛ ² .

Thereafter, 1.0 parts by weight of a subminiature LED element having the specifications shown in Table 1 below, having the structure shown in FIG. 6, and coated with an insulating film as shown in Table 1 below on the active layer of the subminiature LED element was mixed with 100 parts by weight of acetone to form a microminiature LED element. A dispersion solution containing an LED device was prepared.

The prepared dispersion solution was dropped on the electrode line area, and then AC power having a voltage of VAc = 30 V and a frequency of 950 kHz was applied to the electrode line for 1 minute to manufacture a subminiature LED assembly.

division texture Height (μm) Diameter (μm) First mounting electrode layer chrome 0.03 0.5 1st conductive semiconductor layer n-GaN 2.14 0.5 active layer InGaN 0.1 0.5 Second conductive semiconductor layer p-GaN 0.2 0.5 Second mounting electrode layer chrome 0.03 0.5 Insulation film aluminum oxide thickness 0.02 Subminiature LED element - 2.5 0.52

에서 2 분 동안 열처리하였다. 그 후 상기 초소형 LED 전극 어셈블리의 상부에 3000 rpm으로 35 초 동안 스핀코팅방법으로 리프트오프층(LOR 5B, MICROCHEM)을 형성하였고, 150

에서 5 분 동안 소프트베이크 하였다. 상기 리프트오프층의 두께는 600nm 이었다. Example 1 810 to the subminiature LED electrode assembly prepared in Preparation Example 1

was heat treated for 2 minutes. After that, a lift-off layer (LOR 5B, MICROCHEM) was formed on the top of the subminiature LED electrode assembly by spin coating at 3000 rpm for 35 seconds, and

Softbaked for 5 minutes. The thickness of the lift-off layer was 600 nm.

에서 1.5 분 동안 소프트베이크 하였다. 상기 포토레지스트층의 두께는 1.8 ㎛ 이었다.A photoresist layer (DNR-L300-30, Dongjin Semichem) was formed on the upper surface of the lift-off layer by spin coating at 3000 rpm for 35 seconds.

Softbake for 1.5 minutes. The thickness of the photoresist layer was 1.8 μm.

에서 1.5분동안 열처리를 하였고, 그 후 현상용액(AZ300, AZEM)에 170 초 동안 넣어서 현상하였다. 현상을 마친 초소형 LED 전극 어셈블리에 남아있는 포토레지스트층 및 리프트오프층은 측면 간에 1 ㎛의 단차가 형성되었으며, Cr/Au 를 증착하여 리프트오프층의 함몰부분의 일부를 매립하여 증착하였다. 금속증착 후 리프트오프층을 리프트오프하여 금속컨택층을 형성하였다. 상기 금속컨택층은 실장전극상부면을 기준으로 두께가 140 nm이었다.After irradiating the subminiature LED electrode assembly with UV for 24 seconds by the backside exposure method, 110

was heat treated for 1.5 minutes, and then developed by putting it in a developing solution (AZ300, AZEM) for 170 seconds. The photoresist layer and the lift-off layer remaining on the developed subminiature LED electrode assembly had a step of 1 μm formed between the side surfaces, and Cr/Au was deposited to fill in a part of the recessed part of the lift-off layer. After metal deposition, the lift-off layer was lifted off to form a metal contact layer. The metal contact layer had a thickness of 140 nm based on the upper surface of the mounting electrode.

Example 2

It was prepared in the same manner as in Example 1, except that the lift-off layer was not formed.

Example 3

에서 2 분 동안 열처리(RTA) 공정을 수행하지 않은 것을 제외하면, 실시예 1과 동일하게 실시하여 제조하였다.810 to the subminiature LED electrode assembly prepared in Preparation Example 1

It was prepared in the same manner as in Example 1, except that the heat treatment (RTA) process was not performed for 2 minutes.

Example 4

에서 2 분 동안 열처리하였다. 그 후 상기 초소형 LED 전극 어셈블리 상부에 알루미늄(Al) 증착층을 형성하고, 상기 금속증착층의 상부에 3000 rpm으로 35 초 동안 스핀코팅 방법으로 음성 포토레지스트층(DNR-L300-30, 동진쎄미켐)을 형성하였고, 90

에서 1.5 분 동안 소프트베이크 하였다. 상기 음성 포토레지스트층의 두께는 1.8 ㎛ 이었다.810 to the subminiature LED electrode assembly prepared in Preparation Example 1

was heat treated for 2 minutes. After that, an aluminum (Al) deposition layer was formed on the top of the subminiature LED electrode assembly, and a negative photoresist layer (DNR-L300-30, Dongjin Semichem) was spin-coated on top of the metallization layer at 3000 rpm for 35 seconds. was formed, and 90

Softbake for 1.5 minutes. The thickness of the negative photoresist layer was 1.8 μm.

에서 15 분 동안 포토레지스트 리무버에 넣어서 포토레지스트층을 제거하여 금속컨택층을 형성하였다. 상기 금속컨택층은 실장전극상부면을 기준으로 두께가 140 nm이었다.A mask corresponding to the separation space between the first and second mounting electrodes was formed on the upper part of the negative photoresist layer, and UV was irradiated for 3 seconds by direct lithography method, and the subminiature LED electrode assembly irradiated with UV was developed. The photoresist layer corresponding to the separation space between the first mounting electrode and the second mounting electrode was removed by putting it in a solution (AZ300, AZEM) for 60 seconds and developing. Thereafter, the metallization layer corresponding to the removed photoresist layer region was etched by dry etching using CF ₄ under conditions of 50 sccm, 100 W, and 0.055 Torr. Finally, in order to remove the photoresist layer remaining on the subminiature LED electrode assembly, a photoresist remover (AZ 700, AZEM) was used to

for 15 minutes in a photoresist remover to remove the photoresist layer to form a metal contact layer. The metal contact layer had a thickness of 140 nm based on the upper surface of the mounting electrode.

On the other hand, the subminiature LED device of Example 4 used a subminiature LED device including an insulating film on the outer region except for the outer surfaces of both ends of the subminiature LED device.

Comparative Example 1

To perform the electroplating process, the electrolytic plating solution 420 is put into the electrolytic bath 410 . The electrolytic plating solution 420 was prepared by diluting HAuCl ₄ (Aldrich, 99.99% trace netals basis, 30 wt% in dilute HCl) in deionized water to a concentration of 0.05 mM. Next, a working electrode 440, a reference electrode 460, and a counter electrode 450 are immersed in the electrolytic plating solution 420. The subminiature LED electrode assembly manufactured in Preparation Example 1 was used as the working electrode 440, the Ag/AgCl electrode was used as the reference electrode, and the Pt plate was used as the counter electrode. Next, the working electrode 440, the reference electrode 460, and the counter electrode 450 are electrically connected to the power source 430. At this time, the counter electrode 450 is connected to (+) of the power source 430, and the first mounting electrode of the subminiature LED electrode assembly manufactured in Manufacturing Example 1 used as the working electrode 440 is connected to (-). After that, the power source 430 was applied with a -0.2V pulse wave for 25 minutes. The power source 430 was applied for 2 seconds and stopped for 2 seconds to manufacture a subminiature LED electrode assembly having a metal layer. The metal layer had a thickness of 50 nm based on the upper surface of the mounting electrode.

Comparative Example 2

A subminiature LED electrode assembly having a metal layer was manufactured in the same manner as in Comparative Example 1, except that power was applied for 40 minutes. The metal layer had a thickness of 140 nm based on the upper surface of the mounting electrode.

Comparative Example 3

에서 2 분 동안 열처리하여 용매를 제거한 초소형 LED 전극 어셈블리를 제조하였다.* 199 810 to the subminiature LED electrode assembly prepared in Preparation Example 1 above

Heat treatment for 2 minutes to prepare a subminiature LED electrode assembly from which the solvent was removed.

Experimental example

Experimental Example 1

AC power having a voltage of V _Ac = 60 Vpp and a frequency of 60 Hz was applied to the electrode lines for the subminiature electrode assemblies prepared in Examples and Comparative Examples for 1 minute, and subminiature LED elements emitting blue light were observed.

Thereafter, the ratio of the number of subminiature LED elements emitting blue light to the number of subminiature LED elements substantially mounted on the electrode line was measured and shown in Table 2 below.

division Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Percentage (%) ¹⁾ 100 48 24 95 33 33 20 1) "Ratio" in Table 2 shows the relative ratio when Example 1 is set to 100 with respect to the number of blue-emitting subminiature LED elements with respect to the number of mounted subminiature LED elements.

As can be seen from Table 2, Example 1 and Example 4, which satisfy both the process and conditions according to the present invention, have a smaller LED element mounted compared to Examples 2, 3, and Comparative Example, which do not satisfy them. It can be seen that the ratio of the number of blue-emitting subminiature LED elements to the number is higher. Specifically, in Example 1, when developed by the backside exposure method, the photoresist layer is developed so that the upper portion of both ends of the subminiature LED device is further exposed because UV does not pass through the electrode portion of the device, and accordingly, the metal Since the contact layer can more easily cover both ends of the element, even subminiature LED elements with poor connectivity with some electrodes can be connected to the electrodes to improve electrical contact, so the number of blue light emitting subminiature LED elements There were many. From this, it can be seen that the metal layer improves the contactability between the subminiature LED element and the electrode. In addition, since the lift-off layer was not formed in Example 2, both ends of the subminiature LED element connected to the side surfaces of the mounting electrode were metal. The contact layer was not easily formed, and thus the number of LED elements emitting light was small.

In addition, since the heat treatment (RTA) process was not performed in Example 3, the dopant of the subminiature LED element was not activated, and the resistance of the electrode included in the end of the subminiature LED element was high, so the overall resistance of the device was high, Accordingly, the number of LED elements emitting light at the driving voltage was small.

In addition, since Example 4 uses a dry etching method in step (5), etching is directional in a direction perpendicular to the longitudinal direction of the subminiature LED element and parallel to the height direction of the electrode line. In addition, since an insulating film is included, even if some metal is left on the surface of the subminiature LED element, an electrical short circuit does not occur, so the number of subminiature LED elements emitting blue light is large.

In addition, since the thickness of the metal layer formed in Comparative Example 1 was thin, the electrical contact of the subminiature LED element connected to the side of the electrode line could not be improved, and thus the contactability of the subminiature LED element could be improved as much as desired. There was no As can be seen in FIG. 12, electroplating could not easily improve contact between the subminiature LED element and the electrode, and accordingly, the number of the subminiature LED element emitting light was small.

In Comparative Example 2, although the thickness of the formed metal layer was the same, voltage was continuously applied for a long time, so electrodes and devices were damaged or defective, and accordingly, the number of blue-emitting subminiature LED elements was small.

Also, in Comparative Example 3, the number of subminiature LED elements emitting light was small because the contactability of the subminiature LED elements interposed between and connected to the side of the mounting electrode could not be improved.

Experimental Example 2

For Example 1 and Example 2, the time required to lift off the photoresist layer was measured and shown in Table 3 below.

division Example 1 Example 2 liftoff time (s) 60 540

As can be seen from Table 3, it can be seen that the lift-off time of Example 1 including the lift-off layer is much shorter than that of Example 2 which does not include the lift-off layer. As a step was formed between the photoresist layer and the lift-off layer in the lift-off layer, the lift-off layer could be more easily lifted off. However, Example 2, which did not include a lift-off layer, had a long lift-off time because it was difficult to lift-off the photoresist layer because no step difference was generated.

Claims (15)

preparing a substrate, and forming a first electrode and a second electrode spaced apart from each other on the substrate;
disposing a plurality of LED elements on the first electrode and the second electrode;
forming a lift-off layer disposed on the plurality of LEDs and having a part of a side surface recessed; and
forming a first contact electrode disposed on the first electrode and contacting the LED element, and a second contact electrode disposed on the second electrode and contacting the LED element;
The method of manufacturing an LED electrode assembly wherein the first contact electrode and the second contact electrode are formed to fill the recessed side surface of the lift-off layer, respectively. According to claim 1,
The lift-off layer is a method of manufacturing an LED electrode assembly whose side surface is depressed and its width is smaller than the length of the LED element. According to claim 1,
Forming the lift-off layer may include forming a lift-off material layer covering the plurality of LED elements; and
Forming a photoresist layer on the lift-off material layer, and exposing and developing the photoresist layer and the lift-off material layer. According to claim 3,
In the step of exposing and developing, the exposure is a method of manufacturing an LED electrode assembly in which light is irradiated from the upper or rear surface of the substrate. According to claim 3,
In the step of exposing and developing, the lift-off layer is formed so that the side surface is depressed than the developed photoresist layer. According to claim 5,
The lift-off layer is a method of manufacturing an LED electrode assembly in which a side surface of a portion disposed above the plurality of LED elements is recessed. According to claim 1,
Wherein the first contact electrode and the second contact electrode have a thickness of 80 to 400 nm. According to claim 1,
The method of manufacturing an LED electrode assembly comprising an insulating film on an outer surface of the LED element. According to claim 1,
The method of manufacturing an LED electrode assembly comprising an electrode layer disposed on at least one of both ends of the LED element. According to claim 1,
The first contact electrode and the second contact electrode include a protruding portion protruding toward a portion where the first electrode and the second electrode are spaced apart. According to claim 1,
The first contact electrode contacts a first end of the LED element,
The second contact electrode is in contact with the second end of the LED element manufacturing method of the LED electrode assembly. According to claim 11,
The first contact electrode contacts an outer surface of the first end of the LED element,
The second contact electrode is in contact with the outer surface of the second end of the LED element manufacturing method of the LED electrode assembly. According to claim 11,
At least a portion of the first contact electrode is disposed on the first end of the LED element;
The second contact electrode is at least partially disposed on the second end of the LED element. According to claim 1,
The first electrode and the second electrode each extends in a first direction and is spaced apart from each other in a second direction different from the first direction. According to claim 14,
The first contact electrode and the second contact electrode each extend in the first direction and are spaced apart from each other in the second direction.

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