KR20030081666A - Manufacturing Method of Flat Emission Source for Field Emission Display Device - Google Patents

Abstract

PURPOSE: A method of forming a surface electron source for field emission display device is provided to prevent the unnecessary radiation by removing field emission materials from the remaining region except for an emission site. CONSTITUTION: A substrate having a gate electrode, an insulating layer, and a cathode electrode is prepared. A sacrificial layer is formed on an entire surface of the substrate. The sacrificial layer is patterned by using a photo etching method. A hole portion corresponding to an emission site is formed by patterning the sacrificial layer. Carbon-based paste is printed on the entire surface of the sacrificial layer. A carbon-base paste layer is formed on the inside of a hole portion of the sacrificial layer and on a surface of the sacrificial layer. The paste layer of the emission site is selectively removed by applying an etching solution on the substrate.

Description

{Manufacturing Method of Flat Emission Source for Field Emission Display Device}

The present invention relates to a field emission display device, and more particularly, to a method of forming a plane electron source for a field emission display device such that the field emission material constituting the plane electron source does not remain in a portion other than the emission site.

In general, a field emission display device is a flat panel display device that implements an image by using a cold cathode as an electron emission source. Recently, a low work function carbon-based material that emits electrons under low voltage conditions of about 10 to 15V A technique for forming a surface electron source through a thick film process such as screen printing using the above has been studied.

Suitable carbon-based materials for the planar electron source are graphite, diamond-like carbon, carbon nanotubes, and the like. Among them, carbon nanotubes have a very fine radius of curvature of about 100 Å so that an electric field is well concentrated at this end. Thus, electron emission occurs even in a low intensity electric field.

Looking at the method of forming a surface electron source using the carbon nanotubes, first, a paste having a viscosity suitable for printing is prepared by mixing an additive such as a binder with carbon nanotube powder, and using the plated screen mesh to emulate the paste. There is a thick film printing method that selectively prints on the site.

In addition, there is a photolithography method of manufacturing a carbon nanotube paste in which photosensitive materials are mixed, printing the paste on the entire back side of the substrate, and then removing only the paste of the emission site through the exposure and development process.

The thick film printing method is simple in process and is advantageous for manufacturing a small display device, whereas in a field emission display device requiring a tolerance within several micrometers (μm) because a screen mesh made of metal physically expands in a high temperature atmosphere. There is a limit in implementing a fine pattern, and it is not applicable to a large display device of 30 inches or more.

In addition, the photolithography method is easier to manufacture a large display device and to realize a fine pattern compared to a thick film printing method. However, the photosensitive paste must be applied to the entire rear substrate in consideration of the flat leveling characteristics of the surface electron source. In other parts, the field emission material remains.

Particularly, since carbon nanotubes emit electrons even in electric fields of several V / µm intensity, even if a very small amount of carbon nanotubes remain in the portion other than the emission site, a high voltage of the anode voltage, not the voltage difference between the cathode electrode and the gate electrode (Approximately 10 to 15 kV) causes light emission at portions other than the emission site.

Therefore, the method of activating the field emission material may be considered to remove the field emission material remaining in the portion other than the emission site, but the carbon nanotubes of several nanometers (nm) size remain after activation and emit light as before activation. Will cause.

FIG. 13 is an electron micrograph photographing a portion other than an emission site in a field emission display in which a plane electron source is formed by a conventional photolithography method, and shows light emission by a field emission material in which a portion of an original remains.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to prevent the field emission material constituting the surface electron source from remaining at portions other than the emission site, thereby preventing unnecessary light emission. It is to provide a method of forming a circle.

1 is a process flowchart showing a method of forming a plane electron source for a field emission display according to the present invention.

2 to 12 are schematic views at each step for explaining a method of forming a surface electron source for a field emission display device according to the present invention;

FIG. 13 is an electron microscope photograph of a portion other than an emission site in a field emission display in which a plane electron source is formed by a conventional photolithography method; FIG.

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

Preparing a substrate on which a gate electrode, an insulating layer, and a cathode electrode are formed; forming a hole corresponding to an emission site by stacking a sacrificial layer on the entire surface of the substrate and patterning the sacrificial layer by photolithography; Printing and drying the carbon-based paste to form a paste film in the hole portion of the sacrificial layer and the surface of the sacrificial layer, and selectively removing the paste film on the surface of the sacrificial layer and the sacrificial layer by using an etchant to remove the paste film of the emission site. It provides a method of forming a plane electron source for a field emission display device comprising the step of leaving.

The sacrificial layer is preferably made of a metal thin film such as aluminum or a photosensitive film such as a dry film resistor.

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

1 is a process flow chart showing a method of forming a planar electron source for a field emission display device according to an embodiment of the present invention, and FIGS. 2 to 13 are schematic views at each step for explaining a method of forming a planar electron source.

First, as shown in FIG. 2, a plurality of gate electrodes 4 are formed in a line pattern on the substrate 2 along the x-axis direction of the drawing, and insulated on the entire surface of the substrate 2 to cover the gate electrodes 4. A layer 6 is formed, and a plurality of cathode electrodes 8 are formed on the insulating layer 6 in a line pattern perpendicular to the gate electrode 4.

In addition, a plane electron source 10 shown in dotted lines is formed on the cathode electrode 8, and the plane electron source 10 is formed in a line pattern along the cathode electrode 8, or the cathode electrode 8 and the gate are formed. It may be formed in a dot pattern corresponding to the intersection area of the electrode (4).

The above electrode structure is formed of electrons (shown by dashed arrows) at the edges of the surface electron source 10 while an electric field is formed around the surface electron source 10 due to the voltage difference between the cathode electrode 8 and the gate electrode 4. Is emitted, and these electrons collide with the fluorescent film formed on the anode electrode (not shown) to cause light emission.

Here, the surface electron source 10 is a calcination after printing the carbonaceous paste, the carbonaceous paste is preferably carbon nanotubes, graphite, diamond-like carbon or a mixture thereof, the two-day carbon-based material powder Glass frit, ethylcellulose resin, photoinitiator and solvent are added to have a viscosity suitable for printing.

As described above, after preparing the substrate 2 having the above-described electrode structure and the carbonaceous paste for fabricating the surface electron source 10, the sacrificial layer 12 is formed on the entire surface of the substrate 2 as shown in FIG. 3. To cover both the cathode electrode 8 and the insulating layer 6. The sacrificial layer 12 is preferably made of a metal thin film, for example, by vacuum deposition of aluminum to a thickness of 1000 ~ 2000Å.

As shown in FIG. 4, the photoresist film 14 is formed on the sacrificial layer 12, and the surface electron source 10 is formed on the cathode electrode 8 through a known exposure and development process. The portion corresponding to the shunt site is selectively removed to form the hole portion 14a. As a result, the portion of the sacrificial layer 12 corresponding to the emission site is exposed through the hole 14a of the photoresist film 14.

Next, an etchant to corrode the sacrificial layer 12 is applied to the entire surface of the substrate 2, or the substrate 2 is immersed in the etchant to expose the sacrificial layer 12 exposed through the hole 14a of the photoresist layer 14. A portion of the sacrificial layer 12 corresponding to the emission site is removed, and the remaining photoresist film 14 is peeled off so that the sacrificial layer 12 corresponding to the emission site is shown in FIG. 5. The hole part 12a is formed.

As described above, since the patterning of the sacrificial layer 12 using the photoresist film 14 satisfies a tolerance within several micrometers (µm), the hole 12a of the sacrificial layer 12 corresponding to the emission site is finely patterned. It can be formed elaborately.

Next, as shown in FIGS. 6 and 7, the carbon-based paste is printed and dried on the entire surface of the substrate 2, and then the paste layer 16 is formed on the inside of the hole portion 12a of the sacrificial layer 12 and the surface of the sacrificial layer 12. ). When the sacrificial layer 12 is removed using an etchant, the paste layer 16 applied on the sacrificial layer 12 is removed together with the sacrificial layer 12, and surface electrons are formed at the emission site on the cathode electrode 8. Circle 10 is formed.

As such, the sacrificial layer 12 is formed on all portions other than the emission site so that the carbon-based paste applied to the entire surface of the substrate 2 is accurately applied only to the emission site. Particularly, the sacrificial layer of metal made of aluminum is used. (12) is extremely thin, with a thickness of about 1000 to 2000 mm 3, enabling precise printing of the carbon-based paste.

In addition, the sacrificial layer 12 may be made of a photosensitive film in addition to the above-described metal thin film. In this case, since the hole portion corresponding to the emission site can be formed in the photosensitive film itself through a normal exposure and development process, the patterning process of the sacrificial layer can be simplified.

That is, as shown in FIG. 8, when the sacrificial layer 12 ′ is formed of a photosensitive film, the sacrificial layer (ie, the sacrificial layer 12) is formed on the substrate 2 on which the gate electrode 4, the insulating layer 6, and the cathode electrode 8 are formed. 12 ') is laminated, and the sacrificial layer 12' is exposed and developed to form a hole portion 12a 'corresponding to the emission site on the cathode electrode 8.

As shown in FIG. 9, the carbon-based paste is printed and dried on the entire surface of the substrate 2 on the sacrificial layer 12 'and then dried inside the hole 12a' of the sacrificial layer 12 'and the sacrificial layer 12'. The paste film 16 is formed on the surface. Next, when the sacrificial layer 12 'is removed using a stripping solution, the paste film 16 applied on the sacrificial layer 12' is removed together with the sacrificial layer 12 ', and as shown in FIG. The surface electron source 10 is formed in the shunt site.

At this time, the photosensitive film constituting the sacrificial layer 12 'is preferably a dry film resistor (DFR), which does not deteriorate the characteristics of the electron source 10 unless it reacts with the carbonaceous paste. Do not.

As described above, according to the present exemplary embodiment, before the carbonaceous paste is printed, the hole portion 12a is formed in the sacrificial layer 12 by photolithography capable of fine patterning, so that the field emission material is accurately applied only to the emission site. Ensure that no field emission material remains outside of the shunt site.

On the other hand, the surface electron source forming method according to the present embodiment, as described above, in addition to the electrode structure in which the gate electrode 4 is formed below the cathode electrode 8, as shown in FIG. It is also applicable to the electrode structure in which the electrode 8 was formed.

That is, in the electrode structure described above, a plurality of cathode electrodes 8 are formed in a line pattern along the x-axis direction of the drawing, and the insulating layer 6 is formed on the entire surface of the substrate 2 to cover the cathode electrodes 8. On the insulating layer 6, a plurality of gate electrodes 4 are formed in a line pattern perpendicular to the cathode electrode 8, and hole portions h are formed in the gate electrode 4 and the insulating layer 6. The cathode electrode 8 is exposed.

The surface electron source 10 shown in dotted lines is formed on the surface of the cathode electrode 8 exposed by the hole portion h. The electrode structure has a voltage difference between the cathode electrode 8 and the gate electrode 4. As a result of the formation of an electric field around the surface electron source 10, electrons are emitted from the surface of the surface electron source 10.

As described above, the substrate 2 having the electrode structure is prepared, and as shown in FIG. 11, the sacrificial layer 12 is formed on the entire surface of the substrate 2, and then the sacrificial layer ( A hole portion 12a corresponding to the emission site is formed in 12).

Then, a carbon-based paste is printed and dried on the entire surface of the substrate 2 to form a paste film (not shown) inside the hole 12a of the sacrificial layer 12 and the surface of the sacrificial layer 12, and using an etching solution. If 12 is removed, the paste film applied to the surface of the sacrificial layer 12 together with the sacrificial layer 12 is removed, and as shown in FIG. 12, that is, the inside of the hole h of the gate electrode 4 and the insulating layer 6. The plane electron source 10 is formed at the emission site.

In this case, the carbon-based paste constituting the surface electron source 10 may include a photosensitive material that is cured by light. In this case, the cathode electrode 8 is a transparent conductive film, for example, indium tin oxide (ITO; Indium). Tin Oxide) film, and the insulating layer 6 is preferably an opaque glass paste film that does not transmit light.

Therefore, after printing the carbon-based paste, if light is provided through the lower surface of the substrate 2, the light is provided to the carbon-based paste located at the emission site through the transparent cathode electrode 8 so that the surface to the cathode electrode 8 can be provided. The adhesion of the electron source 10 is enhanced.

As described above, the method of forming the planar electron source according to the present embodiment prevents the field emission material from remaining in the portion other than the emission site by using the sacrificial layer 12. To prevent unnecessary light emission.

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 the range of.

As described above, the present invention, which forms the surface electron source using the sacrificial layer, enables precise patterning of the surface electron source, prevents unnecessary light emission by the field emission material remaining in the portion other than the emission site, and manufactures a large-area display device. It is possible to easily implement a plane electron source of a desired shape at a tolerance within several micrometers (μm).

Claims (8)

Preparing a substrate on which a gate electrode, an insulating layer, and a cathode electrode are formed; Stacking a sacrificial layer on the entire surface of the substrate and patterning the sacrificial layer by photolithography to form holes corresponding to emission sites; Printing and drying a carbonaceous paste over the entire substrate on the sacrificial layer to form a paste film in the hole of the sacrificial layer and the surface of the sacrificial layer; And Applying an etchant to the substrate to remove the sacrificial layer and the paste film applied on the surface of the sacrificial layer to selectively leave a paste film of the emission site; Method for forming a plane electron source for a field emission display comprising a. The method of claim 1, And forming a hole in the metal thin film by a photolithography method using a photoresist film, wherein the sacrificial layer is formed of a metal thin film. The method of claim 2, A method of forming a surface electron source for a field emission display device, wherein the metal thin film is made of an aluminum film having a thickness of 1000 to 2000 microns. The method of claim 1, And forming a hole corresponding to the emission site by exposing and developing the photosensitive film, wherein the sacrificial layer is formed of a photosensitive film. The method of claim 4, wherein The method of forming a surface electron source for a field emission display device, wherein the photosensitive film is made of a dry film resistor (DFR). The method of claim 1, And forming a surface electron source for a field emission display device, wherein the carbonaceous paste comprises a photosensitive material cured by light. The method of claim 6, Printing the carbonaceous paste and then providing light through a lower surface of the substrate to enhance adhesion of the paste to the cathode electrode. The method of claim 7, wherein Wherein the cathode is formed of a transparent conductive film and the insulating layer is formed of an opaque glass paste film to selectively provide light to the carbonaceous paste of the emission site upon exposure through the bottom surface of the substrate. Formation method of surface electron source.