KR20050104650A - Electron emission display device and manufacturing method of the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron emission display device for directly growing carbon nanotubes to form an electron emission source, and a method for manufacturing the electron emission display device, wherein the gate electrodes and the cathode electrodes are formed on a substrate. A first step of forming them so that at least a part thereof is located on the same plane while maintaining an insulated state from each other; Forming a catalytic metal layer in electrical contact with a side of the cathode electrode; The structures subjected to the first and second stages are mounted in a chemical vapor deposition (CVD) reactor, and chemical vapor deposition is used to grow carbon nanotubes from the catalytic metal layer to the coplanar gate electrode. A third step; And a fourth step of cutting the ends of the carbon nanotubes fixed to the gate electrode.

Description

Electronic emission display device and manufacturing method thereof {ELECTRON EMISSION DISPLAY DEVICE AND MANUFACTURING METHOD OF THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron emission display device, and more particularly, to an electron emission display device and a method of manufacturing the same, which directly grow carbon nanotubes to form an electron emission source.

In general, an electron emission display device implements a predetermined image by colliding electrons emitted from a first substrate side with a fluorescent layer provided on a second substrate to emit light. A display device using a hot cathode as an electron source and a cold cathode There is a way to use it.

The electron emission display device using the cold cathode is a field emission display device, and the field emission display device includes a field emission (FE) type electron emission display device and a metal-insulator-metal (MIM) type electron emission display device. Devices, metal-insulator-semiconductor (MIS) type electron emission displays and surface conduction electron emission displays and the like are known.

Among these, the FA type electron emission display device forms an electron emission source with materials emitting electrons when an electric field is applied, and arranges driving electrodes around the electron emission source, thereby causing the electric field around the electron emission source by the voltage difference between the driving electrodes. Uses the principle that electrons are emitted from it when is applied. The FA type electron emission display device is greatly affected by the overall quality of the display device depending on the characteristics of the electron emission source.

The FE-type electron emission display device developed early used a microtip electron emission source with a sharp tip whose main material is molybdenum (Mo). However, in order to manufacture a field emission display device having a microtip electron emission source, it is necessary to use a known semiconductor process, which makes the manufacturing process complicated, requires high-level technology and expensive equipment, and makes it difficult to manufacture a large screen display device. There is this.

Accordingly, in the field of FA type electron emission display devices, a technique for forming an electron emission source using a carbon-based material which emits electrons well even under low voltage (approximately 10 to 50 V) driving conditions has been researched and developed. Suitable carbon-based materials for the electron emission source include graphite, diamond-like carbon, carbon nanotubes, etc. Among these, carbon nanotubes have extremely fine curvature radii at the ends, so that electrons may be formed even at low electric fields of 1 to 10 V / μm. It is expected to be an ideal electron emitting material as it emits well.

There is a direct growth method using a catalyst metal as a method of forming an electron emission source using the carbon nanotubes.

However, in the conventional direct growth method, the catalyst metal layer is formed during the formation of structures for electron emission control, that is, an insulating layer for insulation between the driving electrodes and the driving electrodes, and finally, after the structure is completed, the carbon nanotubes. Since the growth is made, there is a fear that the catalytic metal layer is deformed due to the influence of a high temperature process or the like in the structure fabrication process. Deformation of the catalytic metal layer interferes with the even growth of the carbon nanotubes, resulting in poor electron source quality.

In addition, the conventional direct growth method has difficulty in accurately controlling the growth length of the carbon nanotubes or the distance between the ends of the carbon nanotubes and the driving electrode. As a result, the electron emission source manufactured by the conventional direct growth method has a disadvantage in that the electron emission characteristics of the plurality of carbon nanotubes present in the electron emission source of one pixel are different from each other, resulting in non-uniform electron emission characteristics.

Therefore, the present invention is to solve the above problems, an object of the present invention is to prevent the deformation of the catalyst metal layer to enable even growth of the carbon nanotubes while precisely controlling the shape characteristics of the carbon nanotubes constituting the emitter An electron emission display device and a method of manufacturing the same are provided.

In order to achieve the above object, the present invention,

A first step of forming the gate electrodes and the cathode electrodes on the substrate so that at least a part thereof is positioned on the same plane while insulated from each other; , The structures subjected to the first and second steps are mounted in a chemical vapor deposition (CVD) reactor, and the chemical vapor deposition reaction is used to grow carbon nanotubes from the catalytic metal layer to the coplanar gate electrode. And a fourth step of cutting the ends of the carbon nanotubes fixed to the gate electrode.

When the catalyst metal layer is formed in the second step, cobalt (Co), nickel (Ni), iron (Fe), or an alloy thereof may be electroplated, deposited, or sputtered.

When cutting the carbon nanotubes in the fourth step, a direct current voltage may be applied to both the cathode electrode and the gate electrode, or the laser may be directly irradiated to the carbon nanotube portion to be cut.

In addition, the present invention, in order to achieve the above object,

First and second substrates disposed to face each other, gate electrodes and cathode electrodes at least partially positioned on the same plane and insulated from each other on the first substrate, and formed in electrical contact with a side surface of the cathode electrode A second substrate and an electron emission source consisting of a carbon nanotube positioned at an arbitrary distance to the gate electrode positioned at one end of which is fixed to the catalyst metal layer and the other end is coplanar with the catalyst metal layer; An electron emission display device including at least one anode electrode formed thereon and a fluorescent layer formed on one surface of the anode electrode is provided.

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

1 to 5B show an embodiment in which the electron emission display device according to the present invention is applied to a field emission display device, and the electron emission display device according to the present invention will be described using the field emission display device as an example.

1 is a partially exploded perspective view of a field emission display device according to an exemplary embodiment of the present invention, FIG. 2 is a cross-sectional view of the field emission display device shown in FIG. 1, and FIG. 3 is a cross-sectional view of the field emission display device shown in FIG. 1. 1 is a partial plan view of a substrate.

Referring to the drawings, the field emission display device arranges the first substrate 2 and the second substrate 4 having an arbitrary size in a substantially parallel manner at a predetermined interval so that an inner space is formed, and joins them together. The vacuum container which is an external appearance of a display apparatus is comprised. The first substrate 2 is provided with a configuration for emitting electrons by forming an electric field, and the second substrate 4 is provided with a configuration for implementing a predetermined image for emitting visible light by the electrons.

First, the cathode electrodes 4 and the gate electrodes 6 are disposed on the first substrate 2 such that at least some of them are positioned on the same plane while being insulated from each other by the insulating layer 8. That is, in the present embodiment, the line portions 6a of the gate electrode 6 having a predetermined pattern, for example, a stripe shape, on the first substrate 2 are arranged in one direction of the first substrate 2 at random intervals. A plurality of insulating layers 8 are formed along the Y-axis direction of the drawing, and the insulating layer 8 is formed on the entire inner surface of the first substrate 2 while covering the line portions 6a.

On the insulating layer 8, a plurality of cathode electrodes 4 having a predetermined pattern, for example, a stripe shape, are arranged in a plurality of directions along the direction orthogonal to the line portion 6a at random intervals. The opposite portion 6b of the gate electrode 6 is formed between the cathode electrodes 4 on the insulating layer 8. The opposing portion 6b is in contact with and electrically connected to the line portion 6a through a via hole 8a formed in the insulating layer 8, and is connected to the cathode electrode 4 on the insulating layer 8. Located on the same plane

In the present embodiment, when the intersection area between the line portion 6a of the gate electrode 6 and the cathode electrode 4 is defined as the pixel area, one via hole 8a and the opposite part 6b correspond to each pixel area. Can be arranged.

The cathode electrode 4 is formed with a catalytic metal layer 10 in electrical contact with the side thereof. The catalytic metal layer 10 is a seed layer for growing carbon nanotubes, and is made of cobalt (Co), nickel (Ni), iron (Fe), or an alloy thereof. Preferably, the cathode electrode facing the opposing portion 6b is provided. It is formed in accordance with each pixel position at one side edge of (4). To this end, the cathode electrode 4 may form a recess 4a at one edge facing the opposing portion 6b, and the catalyst metal layer 10 may be positioned while filling a part of the recess 4a. .

In the catalyst metal layer 10, an electron emission source 12 including a plurality of carbon nanotubes 12a grown from the catalyst metal layer 10 toward the opposite portion 6b is formed. One end of the carbon nanotubes 12a is fixed to the catalyst metal layer 10, and the other end thereof is positioned at a constant distance from the opposing portion 6b. In this case, each of the carbon nanotubes 12a may be formed to have a length of approximately several hundreds of micrometers.

In the present embodiment, the electron emission source 12 includes the carbon nanotubes 12a and the opposing portions 6b while the carbon nanotubes 12a are spaced apart from the opposing portions 6b by several nm to several tens of micrometers. Has a substantially uniform distance. This feature is characterized in that the carbon nanotubes 12a are grown from the catalyst metal layer 10 to the opposing portion 6b in the process of fabricating the field emission display described below, and then the carbon nanotubes on the opposing portion 6b side. (12a) is due to the process of cutting the tip.

In addition, red, green, and blue fluorescent layers 14 are formed on one surface of the second substrate 4 opposite to the first substrate 2 at random intervals to improve contrast of the screen between the fluorescent layers 14. Black matrix 16 is formed. An anode electrode 18 made of a metal thin film (typically an aluminum thin film) is formed on the fluorescent layer 14 and the black matrix 16. The anode 18 receives a voltage necessary for accelerating the electron beam from the outside and increases the brightness of the screen by a metal back effect.

On the other hand, the anode electrode may be made of a transparent conductive film, for example, indium tin oxide (ITO), not a metal thin film. In this case, an anode electrode made of ITO is first formed on the second substrate 4, and the fluorescent layer 14 and the black matrix 16 are formed thereon, and the fluorescent layer 14 and the black matrix 16 as necessary. A metal thin film may be formed thereon to be used to increase the brightness of the screen. The anode electrode made of ITO may have the same stripe shape as the line portion 6b of the gate electrode 6.

The first substrate 2 and the second substrate 4 configured as described above have a sealing such as frit applied around the substrate at random intervals while the cathode electrode 4 and the fluorescent layer 14 face each other. A field emission display device is constructed by exhausting an internal space formed between materials and maintaining a vacuum state. At this time, a plurality of spacers 20 are disposed in the non-pixel region between the first substrate 2 and the second substrate 4 to maintain a constant gap between the two substrates.

The field emission display device having the above configuration is driven by supplying a predetermined voltage to the gate electrode 6, the cathode electrode 4, and the anode electrode 18 from the outside. For example, the gate electrode 6 has several to several tens of times. A positive voltage of volts is applied to the cathode electrode 4 to a negative voltage of several to several tens of volts, and an anode electrode 18 is applied to a hundredth to several thousand volts of a positive voltage.

As a result, an electric field is formed around the electron emission source 12 due to the voltage difference between the gate electrode 6 and the cathode electrode 4, so that electrons from the ends of the carbon nanotubes 12a, in particular the carbon nanotubes 12a, are attracted. The emitted electrons are attracted by the high voltage applied to the anode electrode 18 and collide with the fluorescent layer 14 of the corresponding pixel to emit light, thereby making a predetermined display.

In this case, in the field emission display device of the present embodiment, the carbon nanotubes 12a constituting the electron emission source 12 are maintained at minute intervals such that the carbon nanotubes 12a constituting the electron emission source 12 are not shorted with the opposing portion 6b. As the distance between the N and the opposing part 6b is made substantially uniform, the electron emission amount is increased and the electron emission characteristic is expected to be uniform.

Next, a method of manufacturing a field emission display device according to an exemplary embodiment of the present invention will be described with reference to FIGS. 4, 5A, and 5B.

Referring to FIG. 4, the manufacturing process of the field emission display device according to the present exemplary embodiment may include a first step S1 of forming cathode electrodes and gate electrodes on a first substrate, and electrical contact with a side surface of the cathode electrode. A second step (S2) of forming a catalytic metal layer, a third step (S3) of growing carbon nanotubes between the cathode electrode and the gate electrode using a chemical vapor deposition (CVD) method, and a gate electrode And a fourth step S4 of cutting the ends of the carbon nanotubes on the side.

1 to 3, in a first step S1, a conductive film is formed on the first substrate 2 and patterned to form a line portion 6a of the gate electrode 6, and the line portions 6a are formed. The insulating layer 8 is formed by thin film deposition or thick film printing of an insulating material on the entire inner surface of the first substrate 2, and the via layer 8 is formed by patterning the insulating layer 8, and the insulating layer 8 is formed. ) And forming a conductive film on the substrate) to form opposing portions 6b of the cathode electrodes 4 and the gate electrode 6.

The second step S2 is to form the catalyst metal layer 10 on one side of the cathode electrode 4 facing the opposing portion 6b, and may include cobalt (Co), nickel (Ni), iron (Fe), or the like. The alloy of is electroplated, deposited or sputtered to form the catalytic metal layer 10. Since the catalytic metal layer 10 of this embodiment forms a structure for controlling the electron emission, that is, the cathode electrodes 4, the gate electrodes 6, and the insulating layer 8, and is formed later, the electric field of this embodiment The emission display can prevent deformation of the catalytic metal layer 10.

In the third step S3, the structure completed through the first step S1 and the second step S2 is mounted in a chemical vapor deposition reactor, and a voltage is applied between the catalyst metal layer 10 and the gate electrode 6. It is made of a process of growing a carbon nanotubes (12a) from the catalyst metal layer 10 to the opposing portion (6b) by introducing a carrier gas containing a hydrocarbon while in the reactor (see Fig. 5a).

As the chemical vapor deposition, known plasma chemical vapor deposition or thermal chemical vapor deposition may be applied. Among them, plasma chemical vapor deposition is a method of generating a glow discharge in a chamber or a reactor by a high frequency power source applied to both electrodes. For example, as a reaction gas for synthesizing carbon nanotubes, C ₂ H ₂ , CH ₄ , C ₂ H ₄ , CO gas and the like are used, and as a catalyst metal, Fe, Ni, Co, etc. are deposited on a Si, SiO ₂ or glass substrate by thermal evaporation or sputtering. The catalytic metal deposited on the substrate is etched using ammonia and hydrogen gas to form nanometer (nm) fine catalyst metal particles, and glow discharge is generated when high frequency power is applied to both electrodes while supplying the reaction gas into the chamber. Generated to synthesize carbon nanotubes from the fine catalyst metal particles on the substrate.

The thermal chemical vapor deposition method includes depositing an alloy of Fe, Ni, Co or three catalyst metals as a catalyst metal on the substrate, etching the substrate with hydrofluoric acid (HF) diluted in water, and etching the etched sample into a quartz boat. Charging a quartz boat to the reactor of the CVD apparatus after mounting thereon, further etching the catalyst metal film using NH3 gas at high temperature to form nanometer (nm) sized fine catalyst metal particles. Carbon nanotubes can be synthesized on these fine catalytic metal particles.

The fourth step S4 is to cut the ends of the carbon nanotubes 12a fixed to the opposing portions 6b to separate the carbon nanotubes 12a from the opposing portions 6b, and to form the cathode electrode 4 and the gate. A process of forming a crack in the carbon nanotubes 12a by applying a DC voltage at a voltage of 14 V, a pulse width of 1 mA, and a pulse period of 10 mA to both ends of the electrode 6 is applied. In addition, a process of directly irradiating a laser to a position of the carbon nanotube 12a to be cut may be applied.

As a result, the electron emission source 12 having undergone the first to fourth steps is characterized in that the carbon nanotubes 12a are separated from each other with the carbon nanotubes 12a spaced apart from the opposing portion 6b of the gate electrode 6 by approximately several nm to several tens of micrometers. The distance between the nanotube 12a and the opposing portion 6b is substantially uniform.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to

As described above, the electron emission display device according to the present invention prevents deformation of the catalyst metal layer to enable even growth of the carbon nanotubes, and grows the carbon nanotubes and cuts the carbon to form an electron emission source. The nanotubes maintain a fine spacing between the gate electrode and the uniform distance between the carbon nanotubes and the gate electrode. Accordingly, the electron emission display device according to the present invention has an effect of improving electron emission uniformity and increasing electron emission amount.

1 is a partially exploded perspective view illustrating an electron emission display device according to an exemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a coupled state of the electron emission display device illustrated in FIG. 1.

3 is a partial plan view of a first substrate of the electron emission display of FIG. 1.

4 is a process flowchart illustrating a manufacturing process of an electron emission display device according to an exemplary embodiment of the present invention.

5A and 5B are partial cross-sectional views of an electron emission display device schematically illustrating pre- and post-cut steps of carbon nanotubes, respectively.

Claims (12)

Forming a gate electrode and a cathode on the substrate such that at least a portion thereof is positioned on the same plane while being insulated from each other; A second step of forming a catalytic metal layer in electrical contact with a side of the cathode electrode; The structure which passed the first step and the second step was mounted in a chemical vapor deposition (CVD) reactor, and while a carrier gas containing hydrocarbon was introduced into the reactor, a voltage was applied between the catalyst metal layer and the gate electrode to thereby provide a structure. Growing carbon nanotubes up to a gate electrode located on the same plane; And A fourth step of cutting the ends of the carbon nanotubes fixed to the gate electrode Method of manufacturing an electron emission display device comprising a. The method of claim 1, The first step is to form the line portions of the gate electrode on the substrate, form an insulating layer over the substrate covering the line portions, form cathode electrodes on the insulating layer, and form via holes between the cathode electrodes on the insulating layer. And forming an opposite portion of the gate electrode over the insulating layer while filling the via hole. The method of claim 2, And forming the line portions of the gate electrode and the cathode electrodes in a stripe pattern orthogonal to each other. The method of claim 1, And forming a recess at one edge of the cathode electrode facing the gate electrode and forming a catalyst metal layer inside the recess. The method according to claim 1 or 4, When forming the catalytic metal layer, a method of manufacturing an electron emission display device for electroplating, depositing or sputtering cobalt (Co), nickel (Ni), iron (Fe) or their alloys. The method of claim 1, And the fourth step comprises applying a direct current voltage across the cathode electrode and the gate electrode. The method of claim 1, A method of manufacturing an electron emission display device, comprising irradiating a laser to a carbon nanotube portion to be cut in the fourth step. First and second substrates disposed to face each other; Gate electrodes and cathode electrodes which are insulated from each other on the first substrate and at least partially positioned on the same plane; A catalytic metal layer formed in electrical contact with a side of the cathode electrode; An electron emission source consisting of carbon nanotubes one end of which is fixed to the catalyst metal layer and the other end of which is positioned at an arbitrary distance to the gate electrode positioned on the same plane as the catalyst metal layer; At least one anode electrode formed on the second substrate; And And a fluorescent layer formed on one surface of the anode electrode. The method of claim 8, The electron emission display device further includes an insulating layer formed over the entire first substrate, the cathode electrodes are formed on the insulating layer, and the gate parts are in electrical contact with the line parts disposed under the insulating layer. And an opposite portion formed between the cathode electrodes on the insulating layer. The method of claim 9, And the line portions of the gate electrode and the cathode electrodes are formed in a stripe pattern orthogonal to each other. The method of claim 8, And a cathode formed at a side edge of the cathode electrode facing the gate electrode, and the catalyst metal layer is in contact with the cathode electrode at a side thereof in the recess. The method according to claim 8 or 11, wherein And the catalyst metal layer is one selected from the group consisting of cobalt (Co), nickel (Ni), iron (Fe), and alloys thereof.