KR20020027956A - Field Emission Display using carbon nanotube developed horizontally - Google Patents

Abstract

PURPOSE: A field emission display using a horizontally grown carbon nano tube is provided to reduce a fabricating cost by using a horizontally carbon nano tube as a cathode or a grid of a cathode plate panel. CONSTITUTION: A field emission display is formed with a cathode plate panel, an anode plate panel, and a grid between the cathode and the anode plate panels. The cathode plate panel includes a horizontal grown carbon nano tube. A predetermined catalytic pattern is formed on an upper face of a substrate. A vertical growth restriction layer is formed on the upper face of the substrate in order to restrict a vertical growth process of a carbon nano tube. An opening portion(46) is formed on an upper portion of the vertical growth restriction layer in order to expose the predetermined catalytic pattern. A horizontal growth process is performed by synthesizing the carbon nano tube with the exposed predetermined catalytic pattern.

Description

Field emission display using carbon nanotube developed horizontally}

The present invention relates to field emission displays, and more particularly to the use of carbon nanotubes as elements of field emission displays.

Field emission display (FED) uses the principle that electrons emitted from the cathode material in the presence of an electric field, that is, an electric field, collide with the phosphor, and emit light. Although many micro-tip FEDs have been developed as a basis, it is known that commercialization is difficult due to many problems such as high cost and high dissipation current between tips due to complicated tip manufacturing process.

Meanwhile, as it is known that FED (hereinafter, referred to as 'CNT-FED') can be manufactured using carbon nanotube, a new material that is in the spotlight, interest in CNT-FED is increasing.

More specifically, the CNT-FED that is currently being shown is largely classified into four types.

First, as shown in FIG. 1, CNTs 10 in a powder form are mixed with a paste 12, and the top layer of the paste, which is a kind of binder, is scraped off so that CNTs are sharply exposed on a plane.

However, this method has two problems that are fatal to commercialization. First of all, enormous outgassing by the binder material 12 used as a paste is mentioned. Binder materials are mostly mixed with organic gases that are highly gaseous, which reduces the vacuum level inside the display, and these gases react with the anode, cathode, phosphor (6) and spacer (8) to cause severe deterioration. It is a technology that is not commercially available because there is a limit to lowering the degree of vacuum using a getter, and even if it is commercialized, its life will be very short.

In addition, the most important thing in the display is uniformity, that is, light having a constant luminance at a desired portion should be emitted, but the carbon nanotubes 10 mixed in the binder 12 are randomly mixed so that the number per unit area (usually 20-30 / 1㎛ ² ), standing angle, the height of the entire nanotube everything is out of control. Therefore, 'CNT-FED by paste' has its limitations in terms of nonuniformity.

Second, as shown in FIG. 2, nanotubes 10 such as 'barley field' are selectively grown on the catalyst pattern 16 through growth in the vertical direction of the nanotubes, and used as the cathode of the FED. However, it is impossible to control all nanotubes to have the same length during nanotube growth. When nanotubes are used as cold cathode materials, their elongated shape is known to have a high aspect ratio of up to 10,000 field emission promoting factors (β). This is due to the geometric shape rather than the material properties of the nanotubes themselves. This high factor value indicates that when nanotubes of different lengths are used as cold cathodes, there is a large nonuniformity in the amount of electron emission between the nanotubes. Disprove that. In fact, the most problematic part in the structure as shown in FIG. 2 is a high nonuniformity according to the height difference of the carbon nanotubes.

Third, there is a method of vertically attaching the nanotube 10 in powder form to the substrate 14 by electrophoresis or self-assembly method as shown in FIG. Electrophoresis method disperses carbon nanotubes in a solution containing chemical functional groups, attaches the chemical functional groups to the ends of the nanotubes, and applies an electric field to attract and attach the nanotubes to the metal electrode pattern 18 by the coulomb force. After aging is done. The self-assembly method induces selective chemisorption (self-assembly) on the selective surface modified pattern 18 on the substrate to align the nanotubes to the desired position on the substrate and prepare the solution. The process of imparting chemical functional groups to is the same as for electrophoresis. However, this structure is more problematic in two aspects compared to FIG. 2, although it has the advantage of lowering the process cost. One is that due to the limitations of the nanotube cutting, grinding, and refining processes, the difference in length between the nanotubes is severe, and the other is that the adhesion between the substrate and the nanotubes is poor due to the limitations of electrophoresis. Therefore, the limitation of using it as a display is clear.

Fourth, there is a CNT-FED fabricated by growing nanotubes directly in a spindt structure mainly used in micro-tips as shown in FIG. However, in this case, the process is complicated, it is difficult to develop the gate 20 material in which the nanotubes do not grow, and it is difficult to control the growth of the nanotubes in the cavity hole 24, which makes vertical growth difficult and consequently leakage. There are many problems, such as a lot of leakage current.

After all, the CNT-FEDs have a big problem in terms of uniformity, life and stability.

The present invention has been made to solve the above problems, an object of the present invention is to provide a uniform CNT-FED without the height difference of the nanotubes.

It is another object of the present invention to provide a CNT-FED having excellent stability that does not reduce the brightness and life of the nanotube burned.

Still another object of the present invention is to provide a CNT-FED having a simple manufacturing process and excellent economic efficiency.

1 is a schematic diagram of a CNT-FED manufactured by a conventional paste mixing method.

2 is a schematic diagram of CNT-FED using conventional vertically grown carbon nanotubes.

3 is a schematic diagram of a vertical alignment CNT-FED manufactured by a conventional electrophoresis and magnetic assembly method.

Figure 4 is a schematic diagram of the CNT-FED synthesized directly CNT in the structure of the conventional Spindt type.

5 is a schematic diagram of a bipolar FED according to the present invention.

6 is a schematic diagram of a triode FED according to the present invention.

7A to 7D are process drawings of horizontally grown carbon nanotubes for use as a cold cathode or grid according to the present invention.

8a to 8d are another manufacturing process diagram of horizontally grown carbon nanotubes for use as a cold cathode or grid according to the present invention.

9A to 9F are structures of various types of horizontally grown carbon nanotubes used as cold cathodes or grids, respectively.

10 is a carbon nanotube having a laminated structure used as a cold cathode or a grid.

11A-11F are structures of various types of horizontally grown carbon nanotubes used as cold cathodes or grids, respectively.

<Description of main parts of drawing>

2 glass 4 ITO (anode plate)

6: phosphor 8: spacer

10 carbon nanotube (cathode) 12 paste (binder)

14 substrate 16 catalyst pattern

18: metal electrode pattern or surface treatment pattern

20: gate 22: insulator

24: cavity hole 30: negative electrode panel

32: cold cathode 34: grid

60: carbon nanotube 70: catalyst pattern

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

As shown in FIG. 5, in the field emission display including the anode plate panel 30 including the carbon nanotubes and the anode plate panel 4 coated with the phosphor 6, the carbon nanotubes 32 of the cathode plate panel are provided. Provides a field emission display that is a horizontally grown carbon nanotube.

Carbon nanotubes are known to have a low work function and are very easy to emit electrons under an electric field. At this time, the alignment direction of the nanotubes does not greatly affect the electron emission, but only the difference between the 'field emission promoting factor (β)'. In other words, in the case of vertically standing nanotubes and horizontally lying nanotubes, if the electric field strength is the same, there is no intrinsic difference in electron emission but only β value difference. Therefore, horizontally laid carbon nanotubes can be used as the cathode of the FED.

Horizontally grown carbon nanotubes used as the cathode may be formed by (a) forming a predetermined catalyst pattern (42) on a substrate (40); (b) forming a layer (44) on the substrate to inhibit vertical growth of carbon nanotubes; (c) exposing the catalyst pattern by forming openings 46 in the substrate and in the layer that inhibits vertical growth; And (d) synthesizing the carbon nanotubes in the exposed catalyst pattern position and horizontally growing them.

In addition, as shown in Figure 8a to 8d (a) forming a mask 48 at a predetermined position on the substrate 40; (b) forming a catalyst pattern 42 on the masked substrate; (c) forming a layer (44) on the substrate to inhibit vertical growth of carbon nanotubes; (d) removing the mask from the substrate and the layer inhibiting vertical growth to form openings 50 to expose the catalyst pattern; And (e) synthesizing and growing horizontally the carbon nanotubes at the exposed catalyst pattern position.

As the layer 44 for suppressing vertical growth of the substrate 40 and the carbon nanotubes, silicon, glass, silicon oxide, indium tin oxide (ITO) coated glass, etc. may be variously used depending on the purpose.

As the catalyst, a metal, an alloy containing the same, a superconducting metal, a specific metal, etc. may be used, and these catalysts may be formed in a predetermined pattern 42 through a process such as lithography, sputtering, evaporation, or the like. Can be formed. The catalyst pattern is selected from the group consisting of straight (see FIGS. 9C, 9D), orthogonal (see FIGS. 9A, 9B), radial, circular (see FIG. 9E), square (see FIG. 9F), wherein the opening 46 ) Is formed at the intersection of the straight pattern, orthogonal or radial pattern, inside the circle, inside the rectangle.

The present invention is not limited to the above catalyst pattern, and if the horizontally grown carbon nanotubes can function as the cathode of the CNT-FED, it can be formed by changing the catalyst pattern.

The openings 46 of FIGS. 7A to 7D may be formed by laser drilling, wet etching, dry etching, photo-lithography, electron beam lithography, and the like. It can be formed through the method of.

The mask 48 of FIGS. 8A to 8D is easily removable by etching, heating, or the like, and is formed on the lower plate through a deposition method.

The carbon nanotube synthesis may be thermal decomposition, catalytic pyrolysis, plasma vapor deposition, hot-filament vapor deposition, etc., hydrocarbon compounds such as methane, acetylene, carbon monoxide, benzene, ethylene may be used as a raw material, synthesis When the time is properly adjusted, they are connected to each other between the catalyst patterns on the opposite exposed surface to form a bridge structure (see FIGS. 9A, 9D, and 9F) or to free-hang structures (FIG. 9B, which are not connected). 9c, 9e), horizontally grown carbon nanotubes can be obtained.

In addition, the negative electrode panel may include a stacked structure in which the horizontally grown carbon nanotubes are stacked in multiple layers as shown in FIG. 10.

As shown in FIG. 6, the present invention also provides a field emission display comprising a negative electrode panel 30, a positive electrode panel 4 coated with phosphor 6, and a grid 34 between the negative electrode panel panel and the positive electrode panel panel. It provides a field emission display in which the grid is horizontally grown carbon nanotubes.

In addition, the negative plate panel 30 may be formed to include horizontally grown carbon nanotubes.

Carbon nanotubes are known to have secondary electron emission characteristics. In other words, when a high energy electron hits a carbon nanotube, a large amount of electrons are emitted. Therefore, when electrons emitted from the cathode collide with the mesh grid, electron amplification occurs and luminance is increased.

The horizontally grown carbon nanotubes used as the grid may be formed in the same manner as the horizontally grown carbon nanotubes used as the cathode. That is, as shown in FIGS. 7A to 7D, (a) forming a predetermined catalyst pattern 42 on the substrate 40; (b) forming a layer (44) on the substrate to inhibit vertical growth of carbon nanotubes; (c) exposing the catalyst pattern by forming openings 46 in the substrate and in the layer that inhibits vertical growth; And (d) synthesizing the carbon nanotubes in the exposed catalyst pattern position and horizontally growing them.

In addition, as shown in Figure 8a to 8d (a) forming a mask 48 at a predetermined position on the substrate 40; (b) forming a catalyst pattern 42 on the masked substrate; (c) forming a layer (44) on the substrate to inhibit vertical growth of carbon nanotubes; (d) removing the mask from the substrate and the layer inhibiting vertical growth to form openings 50 to expose the catalyst pattern; And (e) synthesizing and growing horizontally the carbon nanotubes at the exposed catalyst pattern position.

At this time, the material of the substrate and the vertical growth inhibiting layer, the catalyst material and the catalyst forming method, the opening forming method, the mask material and forming method, the carbon nanotube synthesis method is the same as above.

The catalyst pattern is selected from the group consisting of straight (see FIG. 11C), orthogonal (see FIGS. 11A, 11B, 11D, 11E), radial, circular, and square (see FIG. 11F), wherein the opening is the straight pattern, It is formed at intersections of orthogonal or radial patterns, inside a circle, and inside a rectangle.

The present invention is not limited to the catalyst pattern, and may be formed by changing the catalyst pattern as long as the horizontally grown carbon nanotubes can function as a grid of CNT-FED.

According to the present invention, excellent in terms of uniformity, stability, life, etc., it is possible to provide a low cost CNT-FED.

In addition, the error due to the difference in the length of the nanotube can be reduced, the distance between the anode and the cathode can be closer, the driving voltage can be lowered.

In addition, the use of horizontally grown carbon nanotubes as a grid has the effect of improving the brightness of the FED through the electron amplification action.

Claims (9)

A field emission display comprising a cathode plate panel including carbon nanotubes and a cathode plate panel coated with phosphors, wherein the carbon nanotubes of the anode plate panel are horizontally grown carbon nanotubes. A field emission display comprising a negative plate panel, a positive electrode plate panel coated with phosphor, and a grid between the negative plate panel and the positive plate panel, wherein the grid is a horizontally grown carbon nanotube. The method of claim 2, And wherein the negative plate panel comprises horizontally grown carbon nanotubes. The method of claim 1, wherein the horizontally grown carbon nanotubes are (1) forming a predetermined catalyst pattern on the substrate; (2) forming a layer on the substrate to inhibit vertical growth of carbon nanotubes; (3) exposing the catalyst pattern by forming openings in the substrate and the layer for suppressing vertical growth; And (4) A field emission display, characterized in that formed by a method comprising synthesizing and horizontally growing carbon nanotubes at the exposed catalyst pattern position. The method of claim 1, wherein the horizontally grown carbon nanotubes are (1) forming a mask at a predetermined position on the substrate; (2) forming a catalyst pattern on the substrate on which the mask is formed; (3) forming a layer on the substrate to inhibit vertical growth of carbon nanotubes; (4) removing the mask from the substrate and the layer inhibiting vertical growth to form openings to expose the catalyst pattern; And (5) A field emission display characterized in that it is formed by a method comprising synthesizing and horizontally growing carbon nanotubes at the exposed catalyst pattern position. The method of claim 5, The catalyst pattern is selected from the group consisting of straight, orthogonal, radial, circular and square, and the openings are formed at the intersections of the straight, orthogonal or radial patterns, inside the circle and inside the rectangle. Method of horizontal growth of the tube. The method of claim 4, wherein The catalyst pattern is selected from the group consisting of straight, orthogonal, radial, circular and square, and the openings are formed at the intersections of the straight, orthogonal or radial patterns, inside the circle and inside the rectangle. Method of horizontal growth of the tube. The method of claim 1, The horizontally grown carbon nanotubes of the anode plate panel are connected to each other between the exposed surfaces of the catalyst pattern to form a bridge structure or a free-hang structure that is not connected. . The method of claim 1, The cathode plate panel is a field emission display, characterized in that the stacked structure of the horizontally grown carbon nanotubes are stacked.